NWCG Glossary of Wildland Fire, PMS 205

This glossary provides the wildland fire community a single source for wildland fire and incident management terminology commonly used by the NWCG and its subgroups.

Glossary entries related to Organizations, IT Applications, and NWCG Positions have been removed from the glossary based on term inclusion criteria. For more information about the glossary and the criteria, see the NWCG User Guide for Glossary of Wildland Fire.

Reference Definitions

Some of the terms within this glossary will be followed by initials or will have references or comments at the end of the definition to help broaden the recognition and understanding of the term. An explanation of those references is as follows:

Also called: Means there is another term that may sometimes be in use, but is not defined in this glossary.
Acronym: An abbreviation formed from the initial letters of other words and pronounced as a word. An acronym appears in parentheses following the term.
Initialism: An abbreviation consisting of initial letters pronounced separately. An initialism appears in parentheses following the term.
See: Means there is another, preferred term that should be used instead. In such a case only the preferred term is defined in this glossary.
See Also: Means there are one or more related terms that may also be of interest to the glossary user. The related terms are also defined in this glossary.
Synonym: Means the term is synonymous with another. The terms have the same, or essentially the same, definition and the terms are interchangeable in their use.
Definition Extension: An example, further explanation, or usage guidance in support of the definition.

Glossary Acronyms/Initialisms

6 (1) | A (126) | B (94) | C (160) | D (102) | E (67) | F (261) | G (48) | H (90) | I (83) | J (10) | K (4) | L (74) | M (92) | N (31) | O (47) | P (133) | Q (6) | R (100) | S (221) | T (71) | U (28) | V (37) | W (60) | Z (1)
Name Definition
6 Minutes for Safety (6MFS)
  • A daily safety briefing for wildland fire that focuses on high risk events found within a firefighter's scope of work that are performed on an infrequent basis. Also know as Six Minutes for Safety.  View the Six Minutes for Safety website at https://www.nwcg.gov/committee/6mfs
  • To jettison a load of water or retardant from an aircraft, or terminate a preplanned aircraft maneuver. 
Abort Area
  • A designated area where unused quantities of water or fire retardant may be jettisoned, usually to permit an airtanker to land with less than a full load. 
Above Ground Level (AGL)
  • Term frequently used in aviation operations, usually in connection with a stated altitude. 
Absolute Humidity
  • According to the American Meteorological Society, (Also called Vapor Density.) In a system of moist air, the ratio of the mass of water vapor present to the volume occupied by the mixture; that is, the density of the water vapor component. Source: http://glossary.ametsoc.org/wiki/Absolute_humidity
  • Act of soaking up and retaining a gas in liquid or in a solid; also retention of radiant energy. 
  • Material (usually a flammable liquid) used to initiate or increase the spread of a fire. 
Acceptable Fire Risk
  • The potential fire loss a community is willing to accept rather than provide resources to reduce such losses. 
Accessibility Burn
  • The burning of understory prior to the sale of forest products to improve the efficiency of timber marking and harvesting.
Accounting Code
  • Agency-specific accounting data.  Each agency assigns a specific accounting code to an incident.
Accrual Reports
  • Cost reports utilized for financial obligation purposes.
Action Plan
  • Any tactical plan developed by any element of ICS in support of the incident action plan. 
Active Crown Fire
  • A fire in which a solid flame develops in the crowns of trees, but the surface and crown phases advance as a linked unit dependent on each other. 
Active Fire
  • Any fire that has not been called "out".
Active Resources
Activity Fuels
  • Fuels resulting from, or altered by, forestry practices such as timber harvest or thinning, as opposed to naturally created fuels. 
Actual Time En Route (ATE)
  • Term used in flight planning/following to document actual time spent flying between points. 
Actual Time of Arrival (ATA)
  • Term used in flight planning/following to document time of arrival at a point. 
Actual Time of Departure (ATD)
  • Term used in flight planning/following to document time of departure from a point. 
  • A device for connecting hoses of the same size with non-matching hose threads, or connecting a threaded coupling to a quick-connect coupling. 
Adiabatic Process
  • According to the American Meteorological Society, a process in which a system does not interact with its surroundings by virtue of a temperature difference between them. In an adiabatic process any change in internal energy (for a system of fixed mass) is solely a consequence of working. For an ideal gas and for most atmospheric systems, compression results in warming, expansion results in cooling.  Source: http://glossary.ametsoc.org/wiki/Adiabatic_process.
Adjective Rating
  • A public information description of the relative severity of the current fire danger situation. 
Administrative Payment Team (APT)
  • A team that supports incident agencies by processing payments for resources. Resources may include emergency equipment, casuals, local vendors for supplies, etc. 
Administrative Representative (AR)
  • Individual responsible for incident agency business management functions, such as personnel, procurement, fiscal, etc.
Administrative Workweek
  • Period of seven consecutive calendar days designated in advance by the head of a department (5 U.S.C. 6101(a)).
Administratively Determined (AD)
  • Oral or written statement tending to link its maker to involvement in a particular crime. 
Advanced Life Support (ALS)
  • Advanced life support skills performed by an EMS practitioner or service, e.g. intravenous fluids and drug administration. 
Advancing a Line
  • Moving a hose lay toward a specified area from the point where the hose-carrying apparatus has stopped. 
Advancing Fire
Advancing Front Combustion Stage
  • The period of combustion when a fire is spreading, usually accompanied by flaming combustion that releases heat to sustain the convection column. 
  • According to the American Meteorological Society, the process of transport of an atmospheric property solely by the mass motion of the atmosphere; also the rate of change of the value of the advected property at a given point. Source: http://glossary.ametsoc.org/wiki/Advection.
Adze Hoe
  • A fire-trenching or digging tool having a sharp, tempered blade, which is useful for heavy grubbing, trenching, and light cutting. 
Aerial Detection
  • A system for, or the act of discovering, locating, and reporting fires from aircraft. 
Aerial Fuels
  • Standing and supported live and dead combustibles not in direct contact with the ground and consisting mainly of foliage, twigs, branches, stems, cones, bark, and vines. 
Aerial Ignition
  • Ignition of fuels by dropping incendiary devices or materials from aircraft. 
Aerial Ignition Device (AID)
Aerial Reconnaissance
  • Use of aircraft for detecting and observing fire behavior, values-at-risk, suppression activity, and other critical factors to facilitate command decisions on strategy and tactics needed for fire suppression. 
Aerial Torch
  • An ignition device suspended under a helicopter, capable of dispensing ignited fuel to the ground for assistance in burning out or backfiring. 
  • A statement of declaration in writing and affirmed before an official with authority to administer an oath; a statement of declaration alleging fact to support the issuance of a search or arrest warrant. 
After Action Review (AAR)
  • A structured review or de-brief process of an event, focused on performance standards, that enables participants to discover for themselves what happened, why it happened, and how to sustain strengths and improve on weaknesses. After action reviews, informal or formal, follow the same general format, involve the exchange of ideas and observations, and focus on improving performance. 
Agency Administrator
  • The official responsible for the management of a geographic unit or functional area. The managing officer of an agency, division thereof, or jurisdiction having statutory responsibility for incident mitigation and management. Examples: NPS Park Superintendent, BIA Agency Superintendent, USFS Forest Supervisor, BLM District Manager, FWS Refuge Manager, State Forest Officer, Tribal Chairperson, Fire Chief, Police Chief. 
Agency Certification
  • The process whereby the employing agency or contractor documents that the individual is fully qualified to perform duties and responsibilities for a specified position. 
Agency Dispatch
  • The agency or jurisdictional facility from which resources are allocated to incidents. 
Agency Dispatcher
  • A person working within an agency organization who processes resources to and from incidents. 
Agency Pilot
  • A federal employee pilot or pilot contracted by a federal agency to fly agency, contracted or leased aircraft. This does not include pilots employed by an aircraft vendor as part of an aircraft services contract, such as airtanker contracts, helicopter contracts or other aircraft contracts.
Agency Specific Costs
  • Costs incurred by an agency that address the sole concern of only the agency or are not incurred with mutual benefit. Agency specific costs are not shared.
Agency/Area Coordination Center
  • A facility which serves as a central point for one or more agencies to use in processing information and resource requests. It may also serve as a dispatch center for one of the agencies. 
Air Ambulance
  • A rotary wing aircraft configured, staffed and equipped to respond, care for and transport a patient(s) and approved/licensed by a state to do so. An air ambulance is sometimes referred to as a medevac. 
Air Attack
  • The deployment of fixed-wing or rotary aircraft on a wildland fire, to drop retardant or extinguishing agents, shuttle and deploy crews and supplies, or perform aerial reconnaissance of the overall fire situation. 
Air Attack Base
  • Permanent facility at which aircraft are stationed for use in air attack operations. 
Air Cargo
  • All items for transport and delivery by aircraft. 
Air Contaminant
  • An airborne dust, fume, gas, mist, odor, smoke, vapor, soot, pollen, carbon, acid or particulate matter or any combination thereof. 
Air Crew Member
  • Additional crew member required for accomplishment of the mission such as flight attendant, smokejumper/rappel spotter, cargo loadmaster, helicopter manager, etc. These positions usually do not require any Airman Certificate(s) or a flight physical. Referred to as a Qualified Non-Crew Member in the CFR.   Source: NWCG Standards for Helicopter Operations, PMS 510.
Air Guard
  • A common VHF-FM frequency used by natural resource agency aircraft for emergency radio transmissions. Also called national air safety guard frequency. 
Air Mass
  • According to the American Meteorological Society, a widespread body of air that is approximately homogeneous in its horizontal extent, particularly with reference to temperature and moisture distribution; in addition, the vertical temperature and moisture variations are approximately the same over its horizontal extent.  The properties of the air mass are established while that air was situated over a particular region of the earth's surface. Source: http://glossary.ametsoc.org/wiki/Air_mass.
Air Pack
  • Portable air (not oxygen) tanks with regulators which allow firefighters to breathe while in toxic smoke conditions. Usually rated for 30 minutes of service. Used primarily on fires involving structures or hazardous materials. 
Air Pollution
  • The general term referring to the undesirable addition of substances (gases, liquids, or solid particles) to the atmosphere that are foreign to the natural atmosphere or are present in quantities exceeding natural concentrations. 
Air Pollution Alert
  • A statement issued by an Air Quality Regulatory Agency due to high measured concentrations of pollutants. The alert remains in effect until monitoring shows a decrease in pollutant levels. Should conditions worsen, air pollution warnings and emergencies may be issued. At each stage (alert, warning and emergency) additional emission restrictions are put into effect so as to not intensify the situation. Essentially, at the emergency level all industrial activities and auto usage stop. 
Air Quality
  • "The composition of air with respect to quantities of pollution therein; used most frequently in connection with ""standards"" of maximum acceptable pollutant concentrations. Used instead of ""air pollution"" when referring to programs. "
Air Quality Model
  • Mathematical or quantitative representation or simulation of air quality processes; e.g., emission models, receptor models, or air quality dispersion models. 
Air Stagnation Advisory (ASA)
  • (Also called Air Quality Alerts.)  A statement issued by a National Weather Service forecast office when atmospheric conditions are stable enough such that the potential exists for air pollutants to accumulate in a given area. The statement is initially issued when conditions are expected to last for at least 36 hours. 
Aircraft Accident
  • An unplanned event that does substantial damage or causes serious injuries when associated with the operation of applicable aircraft. Event occurs between the time engine(s) is (are) started or rotors turning for the purpose of commencing flight, until the aircraft comes to rest with engines and propellers or rotors stopped, the brakes set or wheel chocks in place, and all persons have disembarked. 
Aircraft Data Card
  • Card or documentation required to be on board the aircraft which approves use and indicates specific types of use. 
Aircraft Footprint
  • That area on the surface of the earth, runway, or ramp that is covered by the tread of the aircraft tire while the aircraft is motionless. Also called wheel loading. 
Aircraft Ground Mishap
  • An aircraft mishap in which there is no intent to fly. However, the power plants and/or rotors are in operation and damage is incurred requiring replacement or repair of rotors, propellers, wheels, tires, wing tips, flaps, etc., or injury is incurred requiring first-aid or medical attention. 
Aircraft Incident
  • An unplanned event that results in damage which is less than serious aircraft incident criteria, or injuries not requiring medical attention. 
Aircraft Network (AirNet)
  • Applies to radio frequencies primarily used for air operations. 
  • Fixed-wing aircraft certified by FAA as being capable of transport and delivery of fire retardant solutions. 
Alert System
  • A method used to distribute various types of general or time-sensitive information from an NWCG committee to the wildland fire community. Information may include bulletins, advisories, or safety warnings, each with an associated color hash-marked bordered stationary.
  • A sighting device used by lookouts to determine the horizontal bearing and sometimes the vertical angle of a fire from a lookout. 
All Hazard Incident
  • An incident, natural or human-caused, that requires an organized response by a public, private, and/or governmental entity to protect life, public health and safety, values to be protected, and to minimize any disruption of governmental, social, and economic services. One or more kinds of incident (fire, flood, mass casualty, search, rescue, evacuation, etc.) may occur simultaneously as part of an all hazard incident response. 
All Hazards Meteorological Response System (AMRS)
  • A mobile weather data collection and forecasting system consisting of a communications module, weather observing module, and data interigation module. Used by incident meteorologists on an incident. Source: NWS policy 10-402.
All Terrain Vehicle (ATV)
  • Any motorized vehicle designed for or capable of cross-country travel on or immediately over land, water, sand, snow, ice, marsh, swampland, or other terrain. 
  • Char patterns formed on paint or burned wood remains, usually in the shape of blisters. 
Allocated Resources
Allowable Payload
  • The amount of weight that is available for passengers and/or cargo. On the load calculation form it is the operating weight subtracted from the selected weight. 
Altimeter Setting
  • The barometric pressure reading used to adjust a pressure altimeter for variations in existing atmospheric pressure or to the standard altimeter setting (29.92) inches. 
Ambient Air
  • A ground transport vehicle configured, equipped and staffed to respond, care for and transport a patient(s) and approved by a state to do. 
Anchor Point
  • An advantageous location, usually a barrier to fire spread, from which to start constructing a fireline. The anchor point is used to minimize the chance of being flanked by the fire while the line is being constructed. 
Annual Certification
  • Annual review by an employing agency of an individual's position qualifications and documentation certifying that the individual is fully qualified to perform duties and responsibilities for a specified position. Annual certification is based on established performance standards and agency specific requirements. 
Annual Operating Plan (for Fire Weather) (AOP)
  • A procedural guide which describes fire meteorological services provided within the Geographic Area of responsibility, including the National Interagency Fire Center. The guide is based on the National Interagency Agreement and applicable Geographic Area Memorandum of Agreement. 
Annual Plant
  • A plant that lives for one growing season, starting from a seed each year. 
  • A motor-driven vehicle, or group of vehicles, designed and constructed for the purpose of fighting fires. May be of different types such as engines, water tenders, ladder trucks, etc. 
  • The generic name for a high-strength, flame-resistant, synthetic fabric used in the shirts and jeans of firefighters. Nomex ® , a brand name for aramid fabric, is the term commonly used by firefighters. 
Area Command
  • An organization established to: 1) oversee the management of multiple incidents that are each being handled by an incident management team (IMT) organization; or 2) to oversee the management of a very large incident that has multiple IMTs assigned to it. Area Command has the responsibility to set overall strategy and priorities, allocate critical resources based on priorities, ensure that incidents are properly managed, and that objectives are met and strategies followed. 
Area Ignition
  • Ignition of several individual fires throughout an area, either simultaneously or in rapid succession, and so spaced that they add to and influence the main body of the fire to produce a hot, fast-spreading fire condition. Also called simultaneous ignition. 
Area of Influence
  • Delineated area surrounding a base which can be reached first by the ground or air attack units assigned to the base. Also called zone of influence. 
Area Source
  • A source category of air pollution that generally extends over a large area. Prescribed burning, field burning, home heating, and open burning are examples of area sources. 
  • A term used to indicate that the airtanker dropping mechanism is set to allow a programmed release of part or all of the load of fire retardant. 
  • The taking or keeping of a person in custody by legal authority, especially in response to a criminal charge. 
  • At common law, the malicious and willful burning of another?s dwelling, outhouse or parcel; by most modern statutes, the intentional and wrongful burning of someone else's, or one's own, property. Frequently requires proof of malicious or wrongful intent. 
Arson Fire
  • A fire that is intentional and wrongfully set to burn one's own or someone else's property. 
Arson Task Force
  • Group of individuals convened to analyze, investigate and solve arson problems in a particular region. 
  • One who commits arson. 
  • Cardinal direction toward which a slope faces.
Aspirate (Foam)
  • To draw in gases (or other substances); nozzle aspirating systems draw air into the nozzle to mix with the foam solution. 
  1. A fire weather fire danger product based on a thorough evaluation of all pertinent sources of meteorological, fire danger and resource information.
  2. The evaluation and interpretation of measurements, intelligence, and other information to provide a basis for decision-making. 
Assigned Resources
  • Tasks given to resources to perform within a given operational period, based upon tactical objectives in the incident action plan. 
  • Term used as a title for subordinates of the command staff positions. In some cases, assistants are also assigned to unit leader positions in the planning, logistics, and finance/administration sections. Qualifications, technical capability, and responsibility of assistants are normally less than those of the person holding the primary position. 
Assisting Agency
  • Acceptance of information as true without proof or demonstration.
  • An instrument that provides an approximate measure of evapotranspiration by measuring the water loss from an artificial evaporating surface. 
Atmospheric Inversion
  • According to the American Meteorological Society, a departure from the usual decrease or increase with altitude of the value of an atmospheric property; also, the layer through which this departure occurs (the "inversion layer"), or the lowest altitude at which the departure is found ("the base of the inversion"). In fire management usage, nearly always refers to an increase in temperature with increasing height. Source: http://glossary.ametsoc.org/wiki/Inversion
Atmospheric Pressure
  • According to the American Meteorological Society, (also called barometric pressure), the net force per unit area exerted by the atmosphere as a consequence of gravitational attraction exerted upon the column of air lying directly above the point in question.  Atmospheric pressure is independent of the orientation of the surface on which it acts. Source: http://glossary.ametsoc.org/wiki/Atmospheric_pressure
Atmospheric Stability
  • According to the American Meteorological Society, (also called static stability), the ability of the atmosphere at rest to become turbulent or laminar due to the effects of buoyancy.  Air tending to become or remain turbulent is said to be statically unstable; one tending to become or remain laminar is statically stable; and one on the borderline between the two (which might remain laminar or turbulent depending on its history) is statically neutral. Source: http://glossary.ametsoc.org/wiki/Static_stability
Attack a Fire
  • Limit the spread of fire by any appropriate means. 
Attack Line
  • A line of hose, preconnected to the pump of a fire apparatus and ready for immediate use in attacking a fire. Contrasted to supply lines connecting a water supply with a pump or to feeder lines extended from a pump to various points around the perimeter of a fire. 
Attack Time
  • The starting date, hour, and minute of the first suppression work on a fire. 
Attack Unit
  • Single vehicle or aircraft and its associated personnel and material provided for the purpose of responding to and abating a fire or other emergency. 
Attack Unit Response
  • The response of one attack unit to a fire or other emergency with no regard for the number of return trips to that same fire or emergency. 
Attainment Area
  • An area considered to have air quality as good as, or better than, the National Ambient Air Quality Standards (NAAQS) as defined in the Clean Air Act. An area may be in attainment for one or more pollutants but be in nonattainment for one or more other pollutants. 
Automatic Weather Station (AWS)
  • A non-GOES telemetered weather station that provides hourly observations to a local database. 
Automatically Regulated
  • A proportioning method or device that readily adjusts to changes in water flow and or pressure to maintain a desired mix ratio. 
  • A helicopter flight condition in which the lifting rotor is driven entirely by action of air when the helicopter is in motion. 
Auxiliary Pump
  • A secondary pump on an engine in addition to the main pump. Usually of small capacity. 
Available Fuel
  • That portion of the total fuel that would actually burn under various environmental conditions.
Available Resources
Average Annual Precipitation
  • The expected amount of annual rainfall. Average annual precipitation is an important component to determining the Keech-Bryam Drought Index (KBDI). 
Average Relative Humidity
  • Part of the National Fire Danger Rating System (NFDRS). The mathematical average of the maximum and minimum relative humidities measured at a fire weather station from one basic observation time to the next. 
Average Temperature
  • According to the American Meteorological Society, (also called the mean temperature), the average temperature of the air as indicated by a properly exposed thermometer during a given time period, usually a day, a month, or a year. Source: http://glossary.ametsoc.org/wiki/Mean_temperature
  • A smoke emission control strategy that considers meteorological conditions when scheduling prescribed fires in order to avoid incursions into smoke sensitive areas. 
Azimuth (Measurement Technique)
  • Horizontal angle or bearing of a point measured clockwise from true (astronomic) north. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
    • Definition Extension: This method is useful for short distance measurements that do not have to deal with many obstacles and may be difficult on steep ground.
  • Used in some localities to specify fire set to spread against the wind in prescribed burning. 
  • Instantaneous explosion or rapid burning of superheated gases that occurs when oxygen is introduced into an oxygen-depleted confined space. It may occur because of inadequate or improper ventilation procedures. 
  • A fire set along the inner edge of a fireline to consume the fuel in the path of a wildfire or change the direction of force of the fire's convection column. 
Backfire Torch
  • A flame generating device (e.g., a fount containing diesel oil or kerosene and a wick, or a backpack pump serving a flame-jet). 
  • A tactic associated with indirect attack, intentionally setting fire to fuels inside the control line to slow, knock down, or contain a rapidly spreading fire. Backfiring provides a wide defense perimeter and may be further employed to change the force of the convection column. Backfiring makes possible a strategy of locating control lines at places where the fire can be fought on the firefighter's terms. Except for rare circumstance meeting specified criteria, backfiring is executed on a command decision made through line channels of authority. 
Background Level
  • In air pollution control, the concentration of air pollutants in a definite area during a fixed period of time prior to the starting up, or the stoppage, of a source of emission under control. In toxic substances monitoring, the average presence in the environment, originally referring to naturally-occurring phenomena. 
Backing Fire
  1. Fire spreading, or ignited to spread, into (against) the wind or downslope. A fire spreading on level ground in the absence of wind is a backing fire.
  2. That portion of the fire with slower rates of fire spread and lower intensity normally moving into the wind and/or down slope. Also called: heel fire. 

Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.

Backing Wind
  • According to the American Meteorological Society, in the Northern Hemisphere, a wind that rotates in the counterclockwise direction with increasing height. In fire management usage, in the Northern Hemisphere, a wind that rotates in the counterclockwise direction over a given time period (normally a few hours). Source: http://glossary.ametsoc.org/wiki/Backing_wind
Backpack Pump
  • A portable sprayer with hand-pump, fed from a liquid filled container fitted with straps, used mainly in fire and pest control. 
  • A partitioned wall placed in vehicular or aircraft water tanks to reduce shifting of the water load when starting, stopping or turning. 
Ball Valve
  • A valve in which fluid flow is controlled by a ball with a hole drilled through it. In one position, fluid flows through the hole. When the valve is turned 90 degrees (1/4 turn) the hole is perpendicular to the flow and the ball stops the flow. Intermediate valve positions can be used to adjust the flow. 
Bambi Bucket
  • A collapsible bucket slung below a helicopter. Used to dip water from a variety of sources for fire suppression. 
Banking Snags
  • The act of throwing mineral soil about the base of an unlighted snag to prevent its being ignited by a surface fire. 
Barometric Pressure
  • Any obstruction to the spread of fire. Typically an area or strip devoid of combustible fuel. 
  1. The location at which primary logistics functions for an incident are coordinated and administered. There is only one base per incident. (Incident name or other designator will be added to the term "base.") The incident command post may be collocated with the base.
  2. The location of initial attack forces.
Base Area
  • Part of the National Fire Danger Rating System (NFDRS). An area representative of the major fire problems on a protection unit. Base fuel model and slope class are chosen from the base area. 
Base Fuel Model
  • Part of the National Fire Danger Rating System (NFDRS). A representation of the vegetative cover and fuel in a base area. Used in the calculation of fire danger rating. 
Base Hours
  • The number of hours in a daily tour of duty.
Base Observation Time
  • Part of the National Fire Danger Rating System (NFDRS). The time established to take the fire danger observations. It should be at the time of day when the fire danger is normally the highest. The usually agreed upon time is 1:00 pm standard time. This allows time to transmit observations and prepare forecasts. 
Base Station
  • A fixed central radio dispatching station controlling movements of one or more mobile units. 
  • In prescribed burning, the initial line of fire, usually set as a backing fire along a barrier or control line, which serves to contain subsequent burning operations. 
Basic Life Support (BLS)
  • Basic life support skills performed by an EMS practitioner or service, e.g. splinting, bandaging, oxygen administration, use of the AED. 
Basic Workweek
  • Refers to the scheduled workweek of the employee (individual) at the home unit.
Batch Mix
  • Manually adding and mixing a concentrated chemical, such as liquid foam, or powdered or liquid retardant with water, or gelling agents with fuel, into solution in a tank or container. 
Beaufort Wind Scale
  • A system of interactive computer programs for modeling fuel and fire behavior, comprised of two systems: BURN and FUEL. 
  • An observable activity or action demonstrated by an individual in a particular context. 
Belt Weather Kit
  • Belt-mounted case with pockets fitted for anemometer, compass, sling psychrometer, slide rule, water bottle, pencils, and book of weather report forms. Used to take weather observations to provide on-site conditions to the fire weather forecaster or fire behavior analyst. Observations include air temperature, wind speed and direction, and relative humidity. 
  • Something that represents, promotes or enhances a desired outcome, being of positive value and contributing to the attainment of organizational goals. Benefits represent one end of the spectrum of outcomes from fire, with the opposite end being harm, loss or damage. 
  • A ridge of soil and debris along the outside edge of a fireline, resulting from line construction. 
Best Available Control Measures (BACM)
  • An emission limitation action based on the maximum degree of emission reduction (considering energy, environmental, and economic impacts) achievable through application of production processes and available methods, systems, and techniques. 
Billable/Reimbursable Costs
  • Those agency costs that are billable and/or reimbursable as defined by the master or individual cost share agreement.
  • Preburning of fuels adjacent to a control line before igniting a prescribed burn. Blacklining is usually done in heavy fuels adjacent to a control line during periods of low fire danger to reduce heat on holding crews and lessen chances for spotting across control line. In fire suppression, a blackline denotes a condition where there is no unburned material between the fireline and the fire edge. 
Bladder Bag
  • A collapsible backpack portable sprayer made of neoprene or high-strength nylon fabric fitted with a pump. 
Blind Area
  • An area in which neither the ground nor its vegetation can be seen from a given observation point. 
Block Plan
  • A detailed prescription for treating a specified burning block with fire. 
  • Sudden increase in fireline intensity or rate of spread of a fire sufficient to preclude direct control or to upset existing suppression plans. Often accompanied by violent convection and may have other characteristics of a fire storm. 
Board of Review
  • A board or committee selected to review results of fire suppression action on a given unit or the specific action taken on a given fire. The board reviews the results in order to identify reasons for both good and poor action and to recommend or prescribe ways and means of doing an effective and efficient job. Reviews the results of a safety/accident investigation. 
Boiling Liquid Expanding Vapor Explosion (BLEVE)
  1. The failure of a closed container as a result of overpressurization caused by an external heat source.
  2. A major failure of a closed liquid container into two or more pieces when the temperature of the liquid is well above its boiling point at normal atmospheric pressure. 
  • The trunk of a tree. 
Bone Yard
  1. A mop up term. To "bone yard" a fire means to systematically work the entire area, scraping embers off remaining fuel, feeling for heat with the hands, and piling unburned materials in areas cleared to mineral soil.
  2. An area cleared to mineral soil for piling unburned fuels.
Booster Hose
  • The most common type of hose attached and stored on wildland engine booster reels. The hose is made of neoprene and does not appreciably collapse when stored empty. 
Booster Pump
  • An intermediary pump for supplying additional lift in pumping water uphill past the capacity of the first pump. 
Booster Reel
  • A reel for the booster hose mounted on a fire engine, often supplied by the auxiliary pump. This reel usually carries a 1-inch (25 mm) or 3/4 inch (19 mm) hose and frequently contains an electric rewind mechanism. 
Boundary Conditions
  • The temperature and relative humidity of the boundary layer. 
Boundary Layer
  1. According to the American Meteorological Society, the layer of air near a boundary that is affected by friction against that boundary surface, and possibly by transport of heat and other variables across that surface.
  2. According to the American Meteorological Society, (also called the atmospheric boundary layer) the bottom layer of the troposphere that is in contact with the surface of the earth. It is often turbulent and is capped by a statically stable layer of air or temperature inversion. Source: http://glossary.ametsoc.org/wiki/Boundary_layer
Boundary Value
  • The equilibrium moisture content (EMC) commensurate with the boundary conditions and precipitation events of the preceding 24 hours. 
Bowles Bag
  • A neoprene tank designed for attachment to the landing skid frame of a helicopter. It has a capacity of 80 to 100 gallons (303 to 378 liters) of water or retardant. 
Box Canyon
  • A steep-sided, dead end canyon. 
  • The organizational level having functional or geographical responsibility for major parts of incident operations. The branch level is organizationally between section and division/group in the operations section, and between section and unit in the logistics section. Branches are identified by roman numerals or by functional name (e.g. service, support). 
Break a Line
  • To insert a gate valve or some other device into a hose line. 
Break Coupling
  • To detach two pieces of hose by backing the swivel thread off the nipple thread. 
Break Left or Right
  • Means "turn" left or right. Applies to aircraft in flight, usually on the drop run, and when given as a command to the pilot, implies expectation of prompt compliance.
British Thermal Unit (Btu)
  • Amount of heat required to raise 1 pound of water 1 degree Fahrenheit (from 59.50 to 60.50 F), measured at standard atmospheric pressure. 
Broadcast Burning
  • Prescribed burning activity where fire is applied generally to most or all of an area within well defined boundaries for reduction of fuel hazard, as a resource management treatment, or both. 
Brown and Burn
  • Application of herbicide to desiccate living vegetation prior to burning. 
Brownspot Control
  • Prescribed fire to control fungal infection (brown spot disease) of longleaf pine (Pinus palustris) in the "grass" (small seedling) stage.
  • A collective term that refers to stands of vegetation dominated by shrubby, woody plants, or low growing trees, usually of a type undesirable for livestock or timber management. 
Brush Blade
  • Blade attachment with long teeth specially suited to ripping and piling brush with minimum inclusion of soil. Also called brush rake or root rake. 
Brush Fire
  • A fire burning in vegetation that is predominantly shrubs, brush, and scrub growth. 
Brush Hook
  • A heavy cutting tool designed primarily to cut brush at the base of the stem. Used in much the same way as an axe and having a wide blade, generally curved to protect the blade from being dulled by rocks. 
Brush Management
  • Manipulation of stands of brush by manual, mechanical, chemical, or biological means or by prescribed burning for the purpose of achieving land management objectives. 
Brush Patrol Unit
  • Any light, mobile vehicular unit with limited pumping and water capacity for off-road operations. 
  • The building block of foam; bubble characteristics of water content and durability influence foam performance. 
Bucket Drops
  • The dropping of fire retardants or suppressants from specially designed buckets slung below a helicopter. 
  • Sawing through the bole of a tree after it has been felled. 
  1. The cumulative effects of long-term drying on current fire danger.
  2. The increase in strength of a fire management organization.
  3. The accelerated spreading of a fire with time.
  4. Towering cumulus clouds which may lead to thunderstorms later in the day. 
Buildup Index (BUI)
  • A relative measure of the cumulative effect of daily drying factors and precipitation on fuels with a ten-day timelag. 
  • A general alert from an NWCG committee to the wildland fire community regarding the release of subject-specific information such as technical information, equipment updates, accident reports, etc. Depending on the origin and/or the subject content, a green hash-marked bordered stationary may be associated with this type of alert.
Bumpup Method
  • Progressive method of fireline construction on a wildfire without changing relative positions in the line. Work is begun with a suitable space between workers; whenever one worker overtakes another, all of those ahead move one space forward and resume work on the uncompleted part of the line. The last worker does not move ahead until work is completed in his/her space. Forward progress of the crew is coordinated by a crew boss. 
  1. An area burned over by wildland fire.
  2. A reference to a working fire.
  3. An injury to flesh caused by a cauterizing agent, heat from a fire, or a heated object.
    • First Degree Burn: A burn which causes only pain, redness, and swelling.
    • Second Degree Burn: A burn in which the skin is blistered.
    • Third Degree Burn: A flesh burn in which charring occurs.
  4. To be on fire.
  5. To consume fuel during rapid combustion.
  6. A fire in progress or under investigation. 
Burn Block
  • A discrete area within a larger prescribed or fire use project. 
Burn Out
  • Setting fire inside a control line to consume fuel between the edge of the fire and the control line. 
Burn Out Time
  • The duration of flaming and smoldering combustion phases at a specified point within a burn or for the whole burn, expressed in convenient units of time. 
Burn Patterns
  1. The characteristic configuration of char left by a fire. In wildland fires burn patterns are influenced by topography, wind direction, length of exposure, and type of fuel. Definitions are scale-dependent: (1) They can be used to trace a fire's origin; (2) They are influenced by severity and intensity within a stand; (3) They describe the landscape mosaic.
  2. Apparent and obvious design of burned material and the burning path from the area of origin. 
Burn Severity
  • A qualitative assessment of the heat pulse directed toward the ground during a fire. Burn severity relates to soil heating, large fuel and duff consumption, consumption of the litter and organic layer beneath trees and isolated shrubs, and mortality of buried plant parts. 
Burned Area Emergency Response (BAER) Team
  • BAER teams are formed to analyze post-fire conditions and to take immediate emergency stabilization action to prevent loss of life and property and critical and natural resources. It is the Agency Administrator’s responsibility to order or designate a BAER Team.
Burned Area Rehabilitation
  • The post-fire activities prescribed and implemented to rehabilitate and restore fire damaged lands. 
  • Decomposition of material by the application of heat and oxidation. Also applied to propellants and other pyrotechnic mixtures, though the proper term there is "reacting". Also often an element of the crime of arson.
Burning Ban
  • A declared ban on open air burning within a specified area, usually due to sustained high fire danger. 
Burning Conditions
  • The state of the combined factors of the environment that affect fire behavior in a specified fuel type. 
Burning Index
  1. An estimate of the potential difficulty of fire containment as it relates to the flame length at the head of the fire.
  2. A relative number related to the contribution that fire behavior makes to the amount or effort needed to contain a fire in a specified fuel type. Doubling the burning index indicates that twice the effort will be required to contain a fire in that fuel type as was previously required, providing all other parameters are held constant. 
Burning Index Meter
  • A device used to determine the burning index for different combinations of burning index factors. 
Burning Out
  • Setting fire inside a control line to consume fuel located between the edge of the fire and the control line. 
Burning Period
  • That part of each 24-hour period when fires spread most rapidly; typically from 10:00 AM to sundown. 
Burning Priority Rating
  • System of rating slash to indicate the treatment objective, whether or not burning is required to meet that objective, the fuel treatment necessary to achieve successful burning, and the time of year burning should occur. 
Burning Rate
  • Rate at which a propellant and other combustibles burn. 
Burning Rotation
  • The planned number of years between prescribed fires on a specified area. 
Burning Torch
  • A flame generating device (e.g., a fount containing diesel oil or kerosene and a wick, or a backpack pump serving a flame-jet). 
  • An event in which a fire moves through a location or overtakes personnel or equipment where there is no opportunity to utilize escape routes and safety zones, often resulting in personal injury or equipment damage. 
Buying Team
  • A team that supports one or more incidents and is authorized to procure a wide range of services, supplies, and land and equipment rentals. In addition, the Buying Team Leader has the responsibility of coordinating property accountability with the Supply Unit Leader.
Buys Ballots Law
  • According to the American Meteorological Society, a law describing the relationship of the horizontal wind direction in the atmosphere to the pressure distribution; if one stands with the back to the wind, the pressure to the left is lower than to the right in the Northern Hemisphere. Source: http://glossary.ametsoc.org/wiki/Buys_ballot%27s_law
  • A pre-determined complement of tools, equipment and/or supplies stored in a designated location, available for incident use. 
Calculation of Probabilities
  • Evaluation of all factors pertinent to probable future behavior of a going fire and of the potential ability of available forces to perform fire suppression operations on a specified time schedule. 
Calibrated Airspeed
  • Indicated airspeed of an aircraft, corrected for position and instrument error. Equal to true airspeed in standard atmosphere at sea level. 
  • A geographical site(s), within the general incident area, separate from the incident base, equipped and staffed to provide sleeping, food, water, and sanitary services to incident personnel. 
  • The burning of the foliage of a single tree or a small group of trees, from the bottom up. 
  • The stratum containing the crowns of the tallest vegetation present (living or dead), usually above 20 feet. 
Carbon Dioxide (CO2)
  • A colorless, odorless, nonpoisonous gas, which results from fuel combustion and is normally a part of the ambient air. 
Carbon Monoxide (CO)
  • A colorless, odorless, poisonous gas produced by incomplete fuel combustion. 
  • Any substance that can cause or contribute to the production of cancer. 
Cardinal Altitudes
  • Odd or "even" thousand-foot (305 m) altitudes or flight levels. E.g., 5,000, 6,000, 7,000; FL 250, FL 260, and FL 270.
Cardinal Directions
  • North, south, east, west; used for giving directions and information from the ground or air in describing the fire (e.g., the west flank or east flank, not right flank or left flank). 
Cargo Chute
  • A parachute designed and rigged for dropping equipment and supplies from an aircraft. 
Cargo Compartment
  • An internal area of an aircraft specifically designed to carry baggage or cargo. 
Cargo Drop
  • Dropping of equipment or supplies, with or without a parachute, from an aircraft in flight. 
Cargo Hook
  • Mechanically and electrically operated hook attached to the bottom of a helicopter to which a sling load is attached. 
Cargo Net
  • Net attached to the cargo hook of a helicopter, used to carry cargo. Also called cargo sling. 
Cargo Rack
  • Externally mounted rack for transporting supplies or cargo aboard a helicopter. 
Carousel Hook
  • A remote hook attached to the end of a longline. It has four or more individual hooks which can be independently released, allowing the pilot to fly cargo loads to different locations without landing. 
Carrier Fuels
  • The fuels that support the flaming front of the moving fire. 
Category Day
  • A numerical index related to the ability of the atmosphere to disperse smoke. Different agencies use different scales [e.g., in South Carolina, the current scale is based on ventilation factor and ranges from 1 (poor) to 5 (excellent)]. 
  • According to the American Meteorological Society, the height ascribed to the lowest layer of clouds or obscuring phenomena when it is reported as broken, overcast, or obscuration and not classified "thin" or "partial." The ceiling is termed unlimited when the foregoing conditions are not satisfied. Source: http://glossary.ametsoc.org/wiki/Ceiling
Center Firing
  • Method of broadcast burning in which fire is ignited in the center of the area to create a strong draft; additional fires are then ignited progressively nearer the outer control lines (sometimes in one step) as indraft increases so as to draw the flames and smoke toward the center. 
Centrifugal Pump
  • Pump which expels water by centrifugal force through the ports of a circular impeller rotating at high speed. With this type of pump, the discharge line may be shut off while the pump is running without damaging the pump or hose. 
Certifying Official
  • The agency official at the home unit who is responsible for authorizing and granting position certification per agency policy. The agency official is responsible for completing the agency certification block located on the inside front cover of a Position Task Book. 
  • Unit of measure in land survey, equal to 66 feet (20 M) (80 chains equal 1 mile). Commonly used to report fire perimeters and other fireline distances, this unit is popular in fire management because of its convenience in calculating acreage (e.g., 10 square chains equal one acre). 
Chain Lightning
  • Lightning in a long zigzag or apparently broken line. 
Chain of Command
  • A series of management positions in order of authority. 
  1. Carbonaceous material formed by incomplete combustion of an organic material, most commonly wood; remains of burned materials.
  2. In fire simulation, a darkened area within the fire perimeter; usually indicates fire has already passed through; usually created by an opaque material blocking out a selected portion of basic scene illumination. 
Char Height
  • The vertical distance above ground scorched or blackened on a tree bole. 
Charged Line
  • Hose filled with water under pressure and ready to use. 
Chase Truck
  • Vehicle that carries crew gear, supplies, and operational equipment for initial/extended attack. 
Check Line
  • A temporary fireline constructed at right angles to the control line and used to hold a backfire in check as a means of regulating the heat or intensity of the backfire. 
Check Valve
  • A valve that permits flow of liquid through a hose or pipe in one direction but prevents a return flow. Uses include the prevention of backflow on uphill hose lays, loss of prime with centrifugal pumps and chemical contamination in fire chemical mixing systems. 
  • The process whereby resources first report to an incident. Check-in locations include incident command post (ICP), base or camps, staging areas, helibases, or direct to a tactical assignment. 
Chevron Burn
  • Burning technique in which lines of fire are started simultaneously from the apex of a ridge point, and progress downhill, maintaining position along the contour; used in hilly areas to ignite ridge points or ridge ends. 
  • The ICS title for individuals responsible for command of functional sections: Operations, Planning, Logistics, and Finance/Administration. 
Chief of Party
  • The chief of party is responsible to the sending unit dispatcher until destination is reached. Chief of party is responsible for all traveling personnel assigned on the manifest list. 
Circumstantial Evidence
  • Testimony or information not based on actual personal knowledge or observation, but dependent on inference of other facts or experience. For example, testimony that defendant?s cigarette lighter was found in ashes of a fire. 
  • A form of high cloud, composed of ice crystals, which seldom obscures the sun. 
  • A written demand for a specific amount of money or other objects of value, other than ordinary obligations incurred for services, supplies, or things.
  • An individual, partnership, association, corporation, country, the federal government, state, or other political subdivision asserting a right, demand, or claim against another entity.
Class A Foam
  • Foam intended for use on Class A or woody fuels; made from hydrocarbon-based surfactant, therefore lacking the strong filming properties of Class B foam, but possessing excellent wetting properties. 
Class B Foam
  • Foam designed for use on Class B or flammable liquid fires; made from fluorocarbon-based surfactants, therefore capable of strong filming action, but incapable of efficient wetting of Class A fuels. 
Class I Areas (Air Quality)
  • Geographic areas designed by the Clean Air Act subject to the most stringent restrictions on allowable increment of air quality deterioration. Class I areas include Forest Service wildernesses and nation memorial parks over 5,000 acres, National Parks exceeding 6,000 acres, international parks, as well as other designated lands. 
Class II Areas (Air Quality)
  • All areas of the country not designated Class I, including everything from non-Class I areas to urban areas. A greater amount of air pollution can be added to these areas than Class I. 
Clean Air Act
  • A federal law enacted to ensure that air quality standards are attained and maintained. Initially passed by Congress in 1963, it has been amended several times. 
Clear Text
  • The use of plain English in radio communications transmissions. No Ten Codes or agency specific codes are used when using Clear Text. 
  • The prevalent or characteristic meteorological conditions of any place or region, and their extremes. 
Climate Class
  • In NFDRS, one of four classifications of general climate of an area. 
Climatological Breakpoint
  • Points on the cumulative distribution of one fire weather/fire danger index without regard to associated fire occurrence/business. 
Clock Method
  • Means of establishing a flight path to a target on a fire by referring to clock directions from the aircraft's present location, with the nose of the aircraft pointing at 12:00. 
Closed Area
  • An area in which specified activities or entry are temporarily restricted to reduce risk of human-caused fires or to mitigate the risk to human health or safety by potential or on-going wildland fires. 
  • An administrative action limiting or prohibiting access to a specific geographic or jurisdictional area for the purposes of reducing wildfire or the risk it poses to life, property, and/or resources. Example of use: "Pursuant to 36 C.F.R. 261.50 (a) and (b), it is hereby ordered that the prohibitions hereinafter set forth apply to the general forest area of the Ozark-St. Francis National Forests until further notice."
  • A visible cluster of minute water/ice particles in the atmosphere. 
  • Adjective class representing the degree to which the sky is obscured by clouds. In weather forecast terminology, expected cloud cover of about 0.7 or more warrants use of this term. In the National Fire Danger Rating System, 0.6 or more cloud cover is termed "cloudy."
Co-op Fire
  • Refers to federal, state, and local cooperative fire programs. 
Cold Front
  • The leading edge of a relatively cold air mass which displaces warmer air, causing it to rise. If the lifted air contains enough moisture, cloudiness, precipitation and even thunderstorms may result. As fronts move through a region, in the Northern Hemisphere, the winds at a given location will experience a marked shift in direction. Ahead of an approaching cold front, winds will usually shift gradually from southeast to south, and on to southwest. As a cold front passes, winds shift rapidly to west, then northwest. Typical cold front windspeeds range between 15 and 30 mph but can be much higher. 
Cold Line
  • Fireline that has been controlled. The fire has been mopped up for a safe distance inside the line and can be considered safe to leave unattended. 
Cold Trailing
  • A method of controlling a partly dead fire edge by carefully inspecting and feeling with the hand for heat to detect any fire, digging out every live spot, and trenching any live edge. 
Collective Control
  • Controls the pitch angle of the main (helicopter) rotor blades. Used as primary altitude control. 
  • Species of vegetation that establish on a burned (or otherwise denuded) site from seed. 
Combination Nozzle
  • A nozzle is designed to provide either a solid stream or a fixed spray pattern suitable for applying water, wet water or foam solution. Also called: Adjustable Fog Nozzle. 
Combination Nozzle Tip
  • Two attached straight stream nozzle tips of different orifice size used to increase or restrict water flow. 
  • The rapid oxidation of fuel in which heat and usually flame are produced. Combustion can be divided into four phases: preignition, flaming, smoldering, and glowing. 
Combustion Efficiency
  • The relative amount of time a fire burns in the flaming phase of combustion, as compared to smoldering combustion. A ratio of the amount of fuel that is consumed in flaming combustion compared to the amount of fuel consumed during the smoldering phase, in which more of the fuel material is emitted as smoke particles because it is not turned into carbon dioxide and water. 
Combustion Period
  • Total time required for a specified fuel component to be completely consumed. 
Combustion Rate
  • Rate of heat release per unit of burning area per unit of time. 
  • The act of directing, and/or controlling resources by virtue of explicit legal, agency, or delegated authority. 
Command Climate
  • The working environment within the influence of a particular leader or chain of command. The command climate is based on the subordinates' understanding of how they are expected to perform, how they are treated, and how they must conform to the leader's style. 
Command Presence
  • How leaders present themselves to others. The personal attributes and traits that determine whether leaders are worthy of trust and respect from their subordinates. 
Command Staff
  • The command staff consists of the information officer, safety officer and liaison officer. They report directly to the incident commander and may have an assistant or assistants, as needed. 
Communications Unit
  • An organizational unit in the Logistics Section responsible for providing and maintaining communication services at an incident. May also be a facility (e.g., a trailer or mobile van) used to provide the major part of an incident communications center. 
Community Wildfire Protection Plan (CWPP)
  • A plan developed in the collaborative framework established by the Wildland Fire Leadership Council and agreed to by state, tribal, and local government, local fire department, other stakeholders and federal land management agencies managing land in the vicinity of the planning area. A Community Wildfire Protection Plan (CWPP) identifies and prioritizes areas for hazardous fuel reduction treatments and recommends the types and methods of treatment on Federal and non-Federal land that will protect one or more at-risk communities and essential infrastructure and recommends measures to reduce structural ignitability throughout the at-risk community. A CWPP may address issues such as wildfire response, hazard mitigation, community preparedness, or structure protection - or all of the above. 
  • A formal working agreement among agencies to obtain mutual aid. 
  • Spacing between fuel particles.
Compare and Contrast
  1. An investigative technique that involves comparing same sized indicators within an indicator category at separate locations; looking for either differences or similarities in appearance.
    • Definition Extension:  Includes the comparison of overall patterns and pattern clusters.
  2. The practice of comparing and contrasting the fire damage on different surfaces of an object that has been subjected to the oncoming fire.
    • Definition Extension: Typically, the exposed side has more fire effects present than the contrasting protected side that normally has less fire effects visible.

Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.

Compensation-for-Injury Manager
  • Person responsible to the Compensation/Claims Unit Leader for administrative matters arising from serious injuries and fatalities occurring on the incident. 
Compensation/Claims Unit
  • Functional unit within the Finance/Administration Section responsible for the overall management and direction of all Compensation-for-Injury and Claims Specialists assigned to the incident. 
  • A broad description that groups core behaviors necessary to perform a specific function. 
Competent Ignition Source
Compressed Air Foam Systems (CAFS)
  • A generic term used to describe foam systems consisting of an air compressor (or air source), a water pump, and foam solution. 
Computed Gross Weight
  • Term used in calculating from performance charts the permissible helicopter payload at which a helicopter is capable of hovering in ground effect or hovering out of ground effect, based on pressure altitude and air temperature. 
  • A substance that has been concentrated; specifically, a liquid that has been made denser, as by the removal of some of its water. 
Conceptual Model
  • A model that is a diagram or description of a set of relationships between factors that describe how a system works, such as an ecological model. 
  • The process by which a gas becomes a liquid. 
Condition Class
  • Depiction of the degree of departure from historical fire regimes, possibly resulting in alterations of key ecosystem components. These classes categorize and describe vegetation composition and structure conditions that currently exist inside the Fire Regime Groups. Based on the coarse-scale national data, they serve as generalized wildfire rankings. The risk of loss of key ecosystem components from wildfires increases from Condition Class 1 (lowest risk) to Condition Class 3 (highest risk).
Condition of Vegetation
  • Stage of growth or degree of flammability of vegetation that forms part of a fuel complex. Herbaceous stage is at times used when referring to herbaceous vegetation alone. In grass areas minimum qualitative distinctions for stages of annual growth are usually green, curing, and dry or cured. 
  • Heat transfer through a material from a region of higher temperature to a region of lower temperature. 
  • A wildfire response strategy of restricting a wildfire to a defined area, primarily using natural barriers that are expected to restrict the spread of the wildfire under the prevailing and forecasted weather conditions.
  • The strategy employed in appropriate management responses where a fire perimeter is managed by a combination of direct and indirect actions and use of natural topographic features, fuel, and weather factors. 
  • A raging, destructive fire. Often used to connote such a fire with a moving front as distinguished from a fire storm. 
Conflagration Threat
  • Likelihood that a wildfire capable of causing considerable damage will occur. 
Consistency (Foam)
  • Uniformity and size of bubbles. 
Constant Danger
  • Resultant of all fire danger factors that are relatively unchanging in a specific area (e.g., resource values at risk, topography, fuel type, exposure to prevailing wind). 
  • The amount of a specified fuel type or strata that is removed through the fire process, often expressed as a percentage of the preburn weight. 
  • The status of a wildfire suppression action signifying that a control line has been completed around the fire, and any associated spot fires, which can reasonably be expected to stop the fire's spread. 
  1. The status of a wildfire suppression action signifying that a control line has been completed around the fire, and any associated spot fires, which can reasonably be expected to stop the fire's spread.
  2. The act of controlling hazardous spilled or leaking materials. 
Continental Climate
  • Climate that is characteristic of the interior of a land mass of continental size, marked by large annual diurnal and day-to-day ranges of temperature, low relative humidity and irregular precipitation. 
Contingency Actions
  • A back-up plan of action when actions described in the primary plan are no longer appropriate. Contingency actions are required to be taken when the result exceeds its intent. Actions are taken to return the project to its intended design. 
Contingency Plan
  • The portion of a prescribed fire plan, incident action plan, or implementation plan that identifies possible but unlikely events and the contingency resources needed to mitigate those events. 
Contingency Resources
  • Planned and identified fire suppression personnel and equipment that mitigate possible but unlikely events that exceed or are expected to exceed holding resource capabilities. 
  • Any written agreement giving one party a right, a service, or a commodity in exchange for a right, a service, or a commodity. Contracts include land use permits, purchase orders, equipment rental agreements, leases, etc.
Contracted Resource Vendor
  • The name of the company who, through a contract, provides resources to support incident management activities.
Contracting Officer (CO)
  • Agency personnel with specific delegation of procurement authority, also known as warranted Contracting Officer.
Contracting Officer’s Technical Representative (COTR) / Contracting Officer’s Representative (COR)
  • An individual designated by the Contracting Officer to provide technical support for the contract within specific authority and limitations as specified in the delegation. The COTR/COR must be agency certified.
  • Private sector personnel, vendor or business contracted to provide goods and services to a government agency.
Control Force
  • Personnel and equipment used to control a fire. 
Control Line
  • An inclusive term for all constructed or natural barriers and treated fire edges used to control a fire. 
Control Time
  • The time a fire is declared controlled. 
  • The completion of control line around a fire, any spot fires therefrom, and any interior islands to be saved; burned out any unburned area adjacent to the fire side of the control lines; and cool down all hotspots that are immediate threats to the control line, until the lines can reasonably be expected to hold under the foreseeable conditions. 
Controlled Airspace
  • Airspace of defined dimensions within which air traffic control service is provided to IFR and VFR flights in accordance with the airspace classification. 
Controlling Nozzle
  • Shut-off nozzle that permits the nozzle operator to open or close the nozzle or adjust the pattern of the stream. 
  1. The transfer of heat by the movement of a gas or liquid; convection, conduction, and radiation are the principal means of energy transfer.
  2. As specialized in meteorology, atmospheric motions that are predominantly vertical in the absence of wind (which distinguishes this process from advection), resulting in vertical transport and mixing of atmospheric properties. 
Convection Column
  • The rising column of gases, smoke, fly ash, particulates, and other debris produced by a fire. The column has a strong vertical component indicating that buoyant forces override the ambient surface wind. 
Convective Activity
  • General term for manifestations of convection in the atmosphere, alluding particularly to the development of convective clouds and resulting weather phenomena, such as showers, thunderstorms, squalls, hail, tornadoes, etc. 
Convective-lift Fire Phase
  • The phase of a fire when most of the emissions are entrained into a definite convection column. 
  • The term for horizontal air currents merging together or approaching a single point, such as at the center of a low pressure area producing a net inflow of air. When this occurs in the lower atmosphere, the excess air is removed by rising air currents. Expansion of the rising air above a convergence zone results in cooling, which in turn often gives condensation (clouds) and sometimes precipitation. 
Convergence Zone
  1. The area of increased flame height and fire intensity produced when two or more fire fronts burn together.
  2. In fire weather, that area where two winds come together from opposite directions and are forced upwards often creating clouds and precipitation. 
Conversion Burning
  • Burning an area where brush has excluded forest reproduction to prepare the area for tree planting. 
Cooperating Agency
  • An agency supplying assistance including but not limited to direct tactical or support functions or resources to the incident control effort (e.g. Red Cross, law enforcement agency, telephone company, etc).
  • The process of systematically analyzing a situation, developing relevant information, and informing appropriate command authority of viable alternatives for selection of the most effective combination of available resources to meet specific objectives. The coordination process (which can be either intra- or interagency) does not involve dispatch actions. However, personnel responsible for coordination may perform command or dispatch functions within limits established by specific agency delegations, procedures, legal authority, etc. 
Coordination Center
  • Term used to describe any facility that is used for the coordination of agency or jurisdictional resources in support of one or more incidents. 
Coriolis Force
  • An apparent force due to the rotation of the earth that causes a deflection of air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This force maximizes at the poles and is essentially zero at the equator. 
  • Result of chemical reaction between a metal and its environment (i.e., air, water, and impurities in same). 
Cost Sharing Agreements
  • Agreements that document the financial responsibility for incident resource costs, possibly identifying requirements of other party payments. 
Cost Unit
  • Functional unit within the Finance/Administration Section responsible for collecting all cost data, performing cost effectiveness analyses, and providing cost estimates and cost saving advice. 
Council Tool
  • Long-handled combination rake and cutting tool, the blade of which is constructed of a single row of three or four sharpened teeth. Also called fire rake, council rake. 
Counter Fire
  1. Fire set between main fire and backfire to hasten spread of backfire. 
  2. Emergency firing to stop, delay, or split a fire front, or to steer a fire.
  • Device that connects the ends of adjacent hoses or other components of hose. 
  • In aviation, the intended direction of horizontal flight. 
  • The area on the ground covered by the combined aerial parts of plants expressed as a percent of the total area. 
Cover Type
  • The designation of a vegetation complex described by dominant species, age, and form. 
Coverage Level
  • Recommended amount of aerially applied retardant keyed to the NFDRS fuel models and/or fire behavior models. Coverage level 2 represents 2 gallons of retardant per hundred square feet. Levels range from 1 to 6 for most fuel models. A coverage level of greater than 6 is for heavy fuels. The levels can be adjusted for fire behavior. 
Coyote Tactics
  • A progressive line construction duty involving self-sufficient crews which build fire line until the end of the operational period, remain at or near the point while off duty, and begin building fireline the next operational period where they left off. 
  • Fine cracking of glass, usually from heat of fire. 
Creeping Fire
  • Fire burning with a low flame and spreading slowly. 
  • An organized group of firefighters under the leadership of a crew boss or other designated official. 
Crew Shuttle
  • Transportation of fireline personnel to and/or from assigned fireline locations. 
Crew Transport
  • Any vehicle capable of transporting a specified number of personnel in a specified manner. 
Criteria Pollutants
  • Pollutants deemed most harmful to public health and welfare and that can be monitored effectively. They include carbon monoxide (CO), lead (Pb), nitrogen oxides (Nox), sulfur dioxide (SO2), ozone (O3), particulate matter (PM) of aerodynamic diameter less than or equal to 10 micrometers (PM10) and particulate matter of aerodynamic diameter less than or equal to 2.5 micrometers (PM2.5). 
Critical Burnout Time
  • Total time a fuel can burn and continue to feed energy to the base of a forward-traveling convection column. 
Critical Incident Stress Debriefing (CISD)
  • The process in which teams of professional and peer counselors provide emotional and psychological support to incident personnel who are or have been involved in a critical (highly stressful) incident. 
Cross Shot
  • Intersecting lines of sight from two points to the same object, frequently used to determine location of a fire from lookouts. Also called cross bearing. 
Crown Consumption
  • Combustion of the twigs, and needles or leaves of a tree during a fire. 
Crown Cover
  • The ground area covered by the crown of a tree as delimited by the vertical projection of its outermost perimeter. 
Crown Fire
  • A fire that advances from top to top of trees or shrubs more or less independent of a surface fire. Crown fires are sometimes classed as running or dependent to distinguish the degree of independence from the surface fire. 
Crown Out
  • A fire that rises from ground into the tree crowns and advances from tree top to tree top. To intermittently ignite tree crowns as a surface fire advances. 
Crown Ratio
  • The ratio of live crown to tree height. 
Crown Scorch
  • Browning of needles or leaves in the crown of a tree or shrub caused by heating to lethal temperature during a fire. Crown scorch may not be apparent for several weeks after the fire. 
Crown Scorch Height
  • The height above the surface of the ground to which a tree canopy is scorched. 
Crowning Potential
  • A probability that a crown fire may start, calculated from inputs of foliage moisture content and height of the lowest part of the tree crowns above the surface. 
  • The ultimate growth of a cumulus cloud into an anvil-shaped cloud with considerable vertical development, usually with fibrous ice crystal tops, and usually accompanied by lightning, thunder, hail, and strong winds. 
  • A principal low cloud type in the form of individual cauliflower-like cells of sharp non-fibrous outline and less vertical development than cumulonimbus. 
Cup Trench
  • A fireline trench on the downhill side of fire burning on steep slopes that is supposed to be built deep enough to catch rolling firebrands that could otherwise start fire below the fireline. A high berm on the outermost downhill side of the trench helps the cup trench catch material. Also known as gutter trench. 
Curb Weight
  • Weight of a truck empty (without payload and driver) but ready to drive, including a full fuel tank, cooling system, crankcase, tools, spare wheel, and all other equipment specified as standard. 
  • In the 1978 version of NFDRS, the herbaceous stage when herbaceous fuel moisture falls to 30% or less. 
Daily Activity Level
  • Part of the National Fire Danger Rating System (NFDRS). In fire danger rating, a subjective estimate of the degree of activity of a potential human-caused fire source relative to that which is normally experienced. Five activity levels are defined: none, low, normal, high, and extreme. 
Daily Rate
  • Paid on a calendar day basis (0001-2400).
Damage Differential
  • The comparative differences of damage to objects resulting from the fire’s passage.  Definition Extension: One of the underlying principles that govern the interpretation of most fire pattern indicators. This principle may be observed on various surfaces of individual objects or by comparing the damage within adjoining areas of the fire. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
Damage Differential Indicators
  • The amount of fire related destruction to combustible objects determined by comparing opposing sides of an object. 
Dead Fuels
  • Fuels with no living tissue in which moisture content is governed almost entirely by absorption or evaporation of atmospheric moisture (relative humidity and precipitation). 
Debris Burning Fire
  1. In fire suppression terminology, a fire spreading from any fire originally ignited to clear land or burn rubbish, garbage, crop stubble, or meadows (excluding incendiary fires).
  2. In prescribed fire terminology, a fire used to dispose of scattered, piled, or windrowed dead woody fuel, generally in the absence of a merchantable overstory. Its purpose is to reduce unsightly fuel concentrations, or consume unwanted natural fuels to facilitate subsequent resource management or land use actions on the area. 
  • The helibase operational area that includes the touchdown pad, safety circle, hover lanes, and external cargo transport area. 
Deep-Seated Fire
  1. A fire burning far below the surface in duff, mulch, peat, or other combustibles as contrasted with a surface fire.
  2. A fire that has gained headway and built up heat in a structure so as to require greater cooling for extinguishment. 
  • As it refers to atmospheric pressure, a decrease in the central pressure of a low. This is usually accompanied by intensification of the cyclonic circulation (counter-clockwise wind flow around the low). 
  1. Chemical decomposition by burning material in which the reaction is less than sonic velocity, for example, low explosives.
  2. A burning with great heat and intense light. 
  • In a discussion of fire retardant slurries, deterioration of viscosity. 
Delayed Aerial Ignition Devices (DAID)
  • Polystyrene balls, 1.25 inches in diameter, containing potassium permanganate. The balls are fed into a dispenser, generally mounted in a helicopter, where they are injected with a water-glycol solution and then drop through a chute leading out of the helicopter. The chemicals react thermally and ignite in 25-30 seconds. The space between ignition points on the ground is primarily a function of helicopter speed, gear ratio of the dispenser, and the number of chutes used (up to four). 
Delegation of Authority
  • A statement provided to the incident commander by the agency executive delegating authority and assigning responsibility. The delegation of authority can include objectives, priorities, expectations, constraints and other considerations or guidelines as needed. Many agencies require written delegation of authority to be given to incident commanders prior to their assuming command on larger incidents. 
  • Release of resources from an incident in strict accordance with a detailed plan approved by the incident commander. 
Demobilization Unit
  • Functional unit within the planning section responsible for assuring orderly, safe and efficient demobilization of incident resources. 
Dense Layer
  • A layer of clouds whose ratio of dense sky cover to total sky cover is more than one-half. 
Dense Sky Cover
  • Sky cover that prevents detection of higher clouds or the sky above it. 
Density (Foam)
  • The ratio of the original volume of the nonaerated foam solution to the resultant volume of foam. The inverse of expansion. 
Departure from Average Greenness (DA)
  • An NDVI-derived image of vegetation greenness compared to its average greenness for the current week of the year. 
Depth of Burn (DOB)
  • The reduction in forest floor thickness due to consumption by fire. 
Depth of Char Indicators
  • Sometimes referred to as "alligatoring", where combustible material appears to have a fissured or scaly appearance similar to an alligator's hide. Most commonly associated with finished lumber products, such as boards and fence posts.
  • A qualified individual who could be delegated the authority to manage a functional operation or perform a specific task. In some cases, a Deputy could act as relief for a superior. Deputies can be assigned to the incident commander, general staff, and branch directors. 
  • Chemical that, when applied to a living plant, causes or accelerates drying of its aerial parts; used to facilitate burning of living vegetation by substantially lowering fuel moisture content within a few hours. 
Designated Area
  • Those areas identified as principal population centers or other areas requiring protection under state or federal air quality laws or regulations. 
Designated Dispatch Point (DDP)
  • The address where the unit must be physically located, and dispatched from, during the mandatory availability period. 
  • An extreme rapid decomposition of a material in which the reaction is more than a sonic velocity, for example, high explosives. 
Dew Point
  • Temperature to which a specified parcel of air must cool, at constant pressure and water-vapor content, in order for saturation to occur. The dew point is always lower than the wet-bulb temperature, which is always lower than the dry-bulb temperature, except when the air is saturated and all three values are equal. Fog may form when temperature drops to equal the dew point. 
  • A scale drawing showing information about a fire scene. 
Die-Out Pattern Indicators
  • Fingers or islands of less intensely burned areas or areas where the fire has self extinguished. 
Digital Elevation Model
  • A set of points which defines the terrain as numbers for computer applications. This data may be used to draw contours, make ortho photos, slope maps, and drive fire models. 
  • A control strategy used in managing smoke from prescribed fires in which smoke concentration is reduced by diluting it through a greater volume of air, either by scheduling during good dispersion conditions or burning at a slower rate. 
Direct Attack
  • Any treatment applied directly to burning fuel such as wetting, smothering, or chemically quenching the fire or by physically separating the burning from unburned fuel. 
Direct Line
  • Any treatment applied directly to burning fuel such as wetting, smothering, or chemically quenching the fire or by physically separating the burning from unburned fuel. 
Direct Protection Area
  • That area for which a particular fire protection organization has the primary responsibility for attacking an uncontrolled fire and for directing the suppression action. Such responsibility may develop through law, contract, or personal interest of the firefighting agent (e.g., a lumber operator). Several agencies or entities may have some basic responsibilities (e.g., private owner) without being known as the fire organization having direct protection responsibility. 
Directional Vectors
  • The physical characteristics of the indicators that show the direction of fire spread, i.e., advancing, backing, or lateral. 
  • The ICS title for an individual responsible for supervision of a branch. 
  • Determination that a fire exists. Location and reporting of a fire is not required as is with detection. 
Discovery Time
  • Elapsed time from start of fire (known or estimated) until the time of the first discovery that results directly in fire suppression action. 
Discrete Frequency
  • A separate radio frequency most commonly used in air traffic control which reduces frequency congestion by controlling the number of aircraft or other resources operating on a particular frequency. 
  • The implementation of a command decision to move a resource or resources from one place to another. 
Dispatch Center
  • An organization from which resources are ordered, mobilized or assigned to an incident and/or demobilized. The center may process requests, coordinate response, or track resources and information under the delegation of its benefiting agency(s).
Dispatch Center, Current
  • The dispatch center actively supporting an incident and the resources assigned or a resource who is temporarily transferred for official action i.e. details, temporary duty station, etc.
    • Definition extension: The current dispatch center for an incident may change to support other centers, units or agencies. The current dispatch center may be the same as the incident dispatch center or home dispatch center or may be different. Current dispatch center for tactical aviation resources is directly associated with the resource independent of an incident.
Dispatch Center, Home
  • The dispatch center associated with a resource’s home unit. The Home Dispatch Center is responsible for initial mobilization and is the Center associated with the resource when an assignment is completed.
    • Definition extension: Every resource has a home dispatch center.
Dispatch Center, Ordering
  • The current dispatch center for an incident.
Dispatch Center, Sending
  • Either the home or current dispatch center for a resource.
  • The decrease in concentration of airborne pollutants as they spread throughout an increasing volume of atmosphere. 
Display Class
  • In WIMS, a one-digit number representing the number of decision points used to evaluate the magnitude of the Staffing Index. 
Display Class Breakpoints
  • In WIMS, the climatological breakpoints separating the highest staffing levels. Commonly these are the index values corresponding to the 90th and 97th or 80th and 95th percentiles for the staffing index. 
Distance Learning (DL)
  • A concept of providing access to quality wildland fire education and training using appropriate instructional technology, delivered anywhere, anytime to prepare a fire management work force to safely achieve fire management objectives. 
Distance Measuring Equipment (DME)
  • Aircraft navigational equipment that provides the slant range distance in miles (kilometers) from the aircraft to the VOR station to which the DME is tuned, usually at or near an airport. 
Distributed Incident Simulation Exercise (DISE)
  • An on-line mission rehearsal event providing an individual or team with an experiential learning environment utilizing the National Interagency Incident Management System to "game" a computer generated incident from multiple training locations.
  • A weather system usually associated with clouds, rain and/or wind. 
  • Daily, especially pertaining to cyclic actions which are completed within 24 hours, and which recur every 24 hours, such as temperature, relative humidity and wind. 
  • The expansion or spreading out of a horizontal wind field. Generally associated with high pressure and light winds. 
  • The ICS organization level between the branch and the task force/strike team. Divisions are used to divide an incident into geographical areas of operation. Divisions are established when the number of resources exceeds the span-of-control of the operations chief. 
Documentation Unit
  • Functional unit within the planning section responsible for collecting, recording and safeguarding all documents relevant to the incident. 
Dormant Season Burning
  • Prescribed burning early in the dry season before the leaves and undergrowth are completely dry or before the leaves are shed, as an insurance against more severe fire damage later on. 
Double Arsonist
  • An offender who sets two fires at one site, at the same time, in a single event. 
Double Doughnut
  • Two lengths of hose rolled side by side or a single length rolled into two small coils for convenient handling. 
Double Female Coupling
  • A hose-coupling device having two female swivel couplings to permit joining two male hose nipples of the same size and thread type when lines are laid with couplings in opposite or reverse directions. 
Double Jacket Hose
  • Fire hose having two cotton or other fiber jackets outside the rubber lining or tubing. 
Double Male Coupling
  • A hose-coupling device having two male thread nipples for connecting hose and for connecting two female couplings of the same diameter. 
Double Shift
  • Equipment is staffed with 2 operators or crews (1 per shift) and must be ordered and documented on a resource order. (Reference OF-294 general clauses for payment information.) Regardless of hiring method, on-shift time for operated equipment will be recorded with clock hours on the appropriate document, e.g., equipment hired under a daily rate will be posted with start and stop time for daily work.
Doughnut Roll
  • A 50 or 100-foot length of hose or a 50-foot length of hose rolled up for easy handling. There are various ways of forming the doughnut. A convenient one has both couplings close together with the male thread protected by the female coupling. 
  • A calculated reduction in actual payload to provide a margin of safety. 
  • Any steel tracked vehicle equipped with a front mounted blade used for exposing mineral soil.
Dozer Company
  • A resource that includes a dozer, its transportation unit and a standard complement of personnel for its operation. 
Dozer Line
  • Fireline constructed by the front blade of a dozer. 
Dozer Tender
  • Any ground vehicle with personnel capable of maintenance, minor repairs, and limited fueling of dozers. 
  • Drawing water from static sources such as a lake, pond, cistern, river, etc. into a pump which is above the level of the water supply. This is done by removing the air from the pump and allowing atmospheric pressure [14.7 psi (101 kPa) at sea level] to push water through a noncollapsible suction hose into the pump. 
Drain Time
  • The time (minutes) it takes for foam solution to drop out from the foam mass; for a specified percent of the total solution contained in the foam to revert to liquid and drain out of the bubble structure. 
Draped Fuels
  • Needles, leaves, and twigs that have fallen from above and have lodged on lower branches or brush. Draped fuels are part of aerial fuels. 
  • Effect of wind on smoke, retardant drops, paracargo, smokejumper streamers, etc. 
Drift Smoke
  • Smoke that has drifted from its point of origin and is no longer dominated by convective motion. May give false impression of a fire in the general area where the smoke has drifted. 
Drip Torch
  • Hand-held device for igniting fires by dripping flaming liquid fuel on the materials to be burned; consists of a fuel fount, burner arm, and igniter. Fuel used is generally a mixture of diesel and gasoline. 
Drive Axle
  • An axle that supports a portion of the vehicle weight and transmits a driving force to the wheels. 
Drive Wheels
  • Wheels powered by all of the vehicle's drive axles. Dual tires are considered as single wheels. The number of wheels is commonly referenced by the terms "4x2", "4x4", etc. where the first figure indicates the total number of wheels on the ground and the second figure, the number of drive wheels.
  • Precipitation composed exclusively of water drops smaller than 0.02 inches (0.5 mm) in diameter. 
Drop Configuration
  • The type of retardant drop selected to cover a ground target. Terms that can specify the type of drop configuration include Salvo Drop and Trail Drop. 
Drop Pass
  • Indicates that the airtanker has the target in sight and will make a retardant drop on this run over the target. 
Drop Pattern
  • The distribution of an aerially delivered retardant drop on the target area in terms of its length, width, and momentum (velocity x mass) as it approaches the ground. The latter determines the relative coverage level of the fire retardant on fuels within the pattern. 
Drop Zone (DZ)
  • Target area for airtankers, helitankers, cargo dropping. 
  • A period of relatively long duration with substantially below-normal precipitation, usually occurring over a large area. 
Drought Index
  • A number representing the net effect of evaporation, transpiration and precipitation in producing cumulative moisture depletion in deep duff or upper soil layers. 
Drum Lifter
  • Device used to transport a 55-gallon drum (208 L) via sling on a helicopter. 
  • The government furnishes all operating supplies after the equipment arrives at the incident.
Dry Adiabatic Lapse Rate
  • The rate of decrease of temperature with height of a parcel of dry air lifted adiabatically through an atmosphere in hydrostatic equilibrium. Numerically equal to 9.7670 C degrees per km or about 5.40 F degrees per thousand feet. 
Dry Air Mass
  • A portion of the atmosphere that has a relatively low dew point temperature and where the formation of clouds, fog, or precipitation is unlikely. 
Dry Bulb
  • A name given to an ordinary thermometer used to determine the temperature of the air (to distinguish it from the wet bulb). 
Dry Bulb Temperature
  • The temperature of the air measured in the shade 4-8 feet above the ground. 
Dry Episode (DE)
  • A contiguous series of days having a pre-established number of fire ignitions with a fuel dryness level that historically resulted in a significant fire event for a particular area. 
Dry Foam
  • A low expansion foam type with stable bubble structure and slow drain time which is used primarily for resource and property protection. 
Dry Hydrant
  1. Permanent devices with fire engine threads attached to expedite drafting operations in locations where there are water sources suitable for use in fire suppression (e.g., piers, wharves, bridges over streams, highways adjacent to ponds).
  2. Permanently installed supply private fire pumps which depend upon suction sources. Also called suction pipe. 
Dry Lightning Storm
  • Thunderstorm in which negligible precipitation reaches the ground. Also called dry storm. 
Dry Run
  • A trial pass over the target area by a leadplane and/or an airtanker to pinpoint target areas and warn ground personnel of the impending retardant or extinguishing agent drop. 
Dry Storage
  • Refers to dry chemical retardants stored at air attack bases and available for mixing with water. 
Dry-bulb Temperature
  • Temperature of the air. 
Dry-bulb Thermometer
  • In a psychrometer, the thermometer not covered with muslin which is used to determine air temperature.
  • The layer of decomposing organic materials lying below the litter layer of freshly fallen twigs, needles, and leaves and immediately above the mineral soil. 
Durability (Foam)
  • The effective life span of foam bubbles. 
Duty Week
  • Regular number of hours worked per week by a full-time firefighter, excluding overtime. 
  • A circular-like flow of a fluid (such as air or water) drawing its energy from a flow of much larger scale, and brought about by pressure irregularities as in the downwind (lee) side of a solid obstacle. For example, wind conditions may be erratic and may eddy on the downwind side of large rock outcroppings, buildings, etc. 
  1. The place where plant communities meet or where successional stages or vegetative conditions within plant communities come together.
  2. The boundary between two fairly distinct fuel types. 
Edge Firing
  • Method of burning in which fires are set along the edges of an area and allowed to spread inward. 
  • A device used to introduce and mix fire chemical into a water stream. An eductor is a fitting with three ports, an inlet for water flow, an outlet for water flow, and an inlet for fire chemical concentrate. The flow of water through the eductor produces a region of lower pressure at the fire chemical inlet, drawing the chemical into the water stream. 
Effective Windspeed
  • The midflame wind speed adjusted for the effect of slope on fire spread. 
  • A siphon device used to fill an engine's tank when the water source is below or beyond the engine's drafting capability. 
  • Conceptually represents the optimum integration of modern educational methods and professional staff development training with state of the art technology. The primary goal is enhancing on-the-job performance, motivation, and learning performance. 
Elevation Loss
  • In hydraulics, the pressure loss caused by raising water through hose or pipe to a higher elevation (roughly equal to one psi for every two-foot increase in elevation above the pump) (11.3 kPa per meter). 
  • Any incident which requires the response of a fire protection organization's attack units and/or support units. 
Emergency Equipment Rental Agreement (EERA)
  • An agreement written at an incident using an EERA, OF-294. The duration is for the length of the incident only.
Emergency Firefighter (EFF)
  • A person employed as an emergency worker on a forest or wildland fire which threatens damage to property under public management. Emergency firefighters are hired for the duration of the emergency only. 
Emergency Locator Transmitter (ELT)
  • A radio transmitter attached to the aircraft structure which operates from its own power source on 121.5 MHz and 243 MHz. The transmitter transmits a distinctive downward swept audio tone for homing purposes and is designed to function without human action after an accident. 
Emergency Operations Plan
  • The plan that each jurisdiction has and maintains for responding to appropriate hazards. 
Emergency Response Provider
  • Any federal, state, or local emergency public safety, law enforcement, emergency responder, emergency medical (including hospital emergency facilities), and related personnel, agencies, and authorities. It is any organization responding to an emergency, or providing mutual aid support to such an organization, whether in the field, at the scene of an incident, or operations center. 
Emergency Stabilization
  • Planned actions to stabilize and prevent unacceptable degradation to natural and cultural resource, to minimize threats to life or property resulting from the effects of a fire, or to repair/replace/construct physical improvements necessary to prevent degradation of land or resources. 
Emergency Support Function (ESF)
  • Groupings of governmental and certain private sector capabilities and functions into an organizational structure to provide support, resources, program implementation, and services that are most likely needed to support disaster response operations.
  • A release of combustion gases and aerosols into the atmosphere. 
Emission Factor (EFp)
  • The mass of particulate matter produced per unit mass of fuel consumed (pounds per ton, grams per kilogram). 
Emission Rate
  • The amount, or mass of smoke produced per unit of time. For example: Emission Rate = Available Fuel x Burning Rate x Emission Factor. 
Emission Reduction
  • A strategy for controlling smoke from prescribed fires that minimizes the amount of smoke output per unit area treated. 
Emission Standard
  • A general type of standard that limits the mass of a pollutant that may be emitted by a source. The most straightforward emissions standard is a simple limitation on mass of pollutant per unit time (e.g., pounds of pollutant per hour). 
Empty Weight
  • Weight of an aircraft/engine including the structure, power plant, all fixed equipment, all fixed ballast, unusable fuel, undrainable oil, and total quantity of hydraulic fluid. 
Energy Release Component (ERC)
  • The computed total heat release per unit area (British thermal units per square foot) within the flaming front at the head of a moving fire. 
  • Any ground vehicle providing specified levels of pumping, water, and hose capacity but with less than the specified level of personnel. 
Engine Company
  • A resource that includes an engine of a specific type. The type specifies tank capacity, pump rating, hose capacity and number of personnel. 
  • A situation where personnel are unexpectedly caught in a fire behavior-related, life-threatening position where planned escape routes or safety zones are absent, inadequate, or compromised. An entrapment may or may not include deployment of a fire shelter for its intended purpose. These situations may or may not result in injury. They include "near misses."
Entrapment Avoidance
  • A process used to improve the safety of personnel on the fireline, which emphasizes tools and tactics available to prevent being trapped in a burnover situation. This process includes appropriate decision making through risk management, application of LCES, use of pre-established trigger points, and recognition of suitable escape routes and safety zones. 
  • Direct attack with multiple anchor points, that allows for multiple points of attack. Generally used as an engine tactic in the wildland urban interface. 
  • The complex surroundings of an item or area of interest, such as air, water, natural resources, and their physical conditions (temperature, humidity). 
Environmental Lapse Rate
  • The actual rate of decrease of temperature with elevation. 
Episode (Pollution)
  • A condition of poor contaminant dispersion which may result in concentrations considered potentially harmful to health or welfare. Episodes may also occur during periods of fairly good dispersion if the source of air contaminants is extremely large. 
Equilibrium Moisture Content (EMC)
  • Moisture content that a fuel particle will attain if exposed for an infinite period in an environment of specified constant temperature and humidity. When a fuel particle reaches equilibrium moisture content, net exchange of moisture between it and its environment is zero. 
Equipment Use Fire
  • Fire caused by mechanical equipment other than railroad operations. 
Escape Route
  • A preplanned and understood route firefighters take to move to a safety zone or other low-risk area. When escape routes deviate from a defined physical path, they should be clearly marked (flagged). 
Escaped Fire
  • Fire which has exceeded or is expected to exceed initial attack capabilities or prescription. 
ESF Coordinator
  • An entity which oversees the preparedness activities for a particular ESF and coordinates with its primary and support agencies.
ESF Primary Agency
  • A Federal agency with significant authorities, roles, resources, and capabilities for a particular function within an ESF.
ESF Support Agency
  • An entity with specific capabilities or resources that support the primary agencies in executing the mission of the ESF.
Estimated Position Error (EPE)
Estimated Time En Route (ETE)
  • Term used in resource planning/following to estimate time spent between points. 
Estimated Time of Arrival (ETA)
  • Term used in resource planning/following to estimate time of arrival at a point. 
Estimated Time of Departure (ETD)
  • Term used in resource planning/following to estimate time of departure from a point. 
  • An organized, phased, and supervised withdrawal, dispersal, or removal of civilians from dangerous or potentially dangerous areas, and their reception and care in safe areas. 
  • To review and compare outcomes with management and incident objectives desired for a wildland fire. One of the six component activities in an adaptive management process that may lead to adjusting future actions. 
  • The individual who is qualified in the position being evaluated, or supervises the position being evaluated, having responsibility for observing task(s) being performed and documenting successful performance for agency certification or re-certification. Evaluator responsibilities must remain separate from the individual assigned as Trainer/Coach. 
  • The transformation of a liquid to its gaseous state; heat is released by the liquid during this process. 
  • A planned, non-emergency activity. ICS can be used as the management system for a wide range of events, e.g., parades, concerts or sporting events. 
Evidence Protection Area
Exempt / Nonexempt
  • Categories of employees as defined in the Fair Labor Standards Act (FLSA), who are either covered or exempted from coverage under the ActPay entitlements vary depending on the employee's FLSA status. 
Exhaust Primer
  • Device which uses the exhaust gas flow of an engine for priming a centrifugal pump. 
Expanded Dispatch
  • An organization needed to support an incident which expands along with the Incident Command System. 
  • The ratio of the volume of the foam in its aerated state to the original volume of the non-aerated foam solution. 
Expert Witness
  • Someone with sufficient skill, knowledge, or experience in a given field so as to be capable of drawing inferences or reaching conclusions or opinions that an average person would not be competent to reach. The expert's opinion testimony should aim the judge or jury in their understanding of the fact at issue. 
Exposed Side
  1. Property that may be endangered by a fire burning in another structure or by a wildfire.
  2. Direction in which a slope faces, usually with respect to cardinal directions.
  3. The general surroundings of a site with special reference to its openness to winds. 
Exposure Fire
  • Classification for a fire not originating in a building, but which ignites building(s). A fire originating in one building and spreading to another is classified under the original cause of fire. 
  • To drop retardant in such a way that the load slightly overlaps and links a previous drop. "Extend your last drop."
Extended Attack
Extended Attack Incident
  • An incident that exceeds the capability of the initial attack resources and/or organization to successfully manage the incident to conclusion. 
Exterior Fire Protection
  • The protection of structures from the exterior, with no interior access or activity. 
External Load
  • A load that is carried or extends outside of the aircraft fuselage. 
External Payload
  • Maximum external stress load (in pounds) with full fuel and pilot in calm air at standard atmospheric temperature. 
Extinguishing Agent
  • Substance used to put out a fire by cooling the burning material, blocking the supply of oxygen, or chemically inhibiting combustion. 
Extra Burning Period
  • For any particular fire which is neither contained nor controlled, any 24-hour period following the termination of the first burning period. 
Extreme Fire Behavior
  • Extreme implies a level of fire behavior characteristics that ordinarily precludes methods of direct control action. One or more of the following is usually involved: high rate of spread, prolific crowning and/or spotting, presence of fire whirls, strong convection column. Predictability is difficult because such fires often exercise some degree of influence on their environment and behave erratically, sometimes dangerously. 
  • Person who sees evidence of criminal activity, actual commission of a crime or a criminal fleeing a crime scene. 
Facilities Unit
  • Functional unit within the logistics section that provides the layout, activation, and management of all incident facilities. These facilities may include the incident base, feeding areas, sleeping areas, sanitary facilities, etc. 
  • A temperature scale on which 320 F denotes the temperature of melting ice, and 2120 F the temperature of boiling water, both under standard atmospheric pressure. 
  • A person who fells trees. Also known as sawyer and cutter. 
False Alarm
  • A reported smoke or fire requiring no suppression; for example, brush burning under control, mill smoke, false smoke, etc. 
Federal Aviation Regulation (FAR)
  • Refers to the regulations governing all aviation activities of civil aircraft within the United States and its territories. 
Federal Coordinating Officer (FCO)
  • The person appointed by the President to coordinate federal assistance in the designated area following the declaration of a major disaster or emergency under the Stafford Act.
Federal Fire Policy
  • Principles and policies providing a common approach to wildland fire for federal agencies. The primary, interagency wildland fire policy document is the "Review and Update of the 1995 Federal Wildland Fire Management Policy" (January 2001). Implementation of that policy is through the "Guidance for Implementation of Federal Wildland Fire Management Policy" (February 2009).
Federal Wage System Employee
  • Regular federal government employee who is compensated under the Federal Wage System and referred to as wage grade (WG), wage leader (WL), or wage supervisor (WS) employee.
Female Coupling
  • Coupling made to receive a male coupling of the same thread, pitch and/or diameter. 
Field Test
  • A job-related test of work capacity designed for those with moderately strenuous duties. This test consists a two-mile hike with a 25-pound pack. A time of 30 minutes, the passing score for this test, approximates an aerobic fitness score of 40. 
Fill Tank
  • Large, portable tank from which helitankers can hoverfill. 
  • An increase in the central pressure of a low. Counter-clockwise wind flow around the low usually decreases as filling occurs. 
Final Approach
  • Flight path in the direction of the landing along the extended runway center line from the base leg to the runway. 
Final Evaluator
  • The individual responsible for completing the position task book's verification statement once all tasks in the position task book have been completed and signed off. Only the evaluator on the final position performance assignment (the assignment in which all remaining tasks have been evaluated and signed off) will complete the verification statement recommending certification. 
Final Run
  • An airtanker is "on final" when it is on line with the target and intends to make the drop on that pass; also applies to cargo dropping. 
Finance/Administration Section
Fine Fuel Moisture
  • The probable moisture content of fast-drying fuels which have a timelag constant of 1 hour or less; such as, grass, leaves, ferns, tree moss, pine needles, and small twigs (0-1/4"). 
Fine Fuels
  • Fast-drying dead or live fuels, generally characterized by a comparatively high surface area-to-volume ratio, which are less than 1/4-inch in diameter and have a timelag of one hour or less. These fuels (grass, leaves, needles, etc.) ignite readily and are consumed rapidly by fire when dry.
Fingers of a Fire
  • The long narrow extensions of a fire projecting from the main body. 
FIRDAT (Fire Data Manipulation Program)
  • A routine of FIREFAMILY that combines historical weather records with the equations of the NFDRS to produce frequency distributions of the NFDRS indexes and components. 
  • Rapid oxidation, usually with the evolution of heat and light; heat fuel, oxygen and interaction of the three. 
Fire Adapted Community (FAC)
  • A human community consisting of informed and prepared citizens collaboratively planning and taking action to safely co-exist with wildland fire. 
Fire Agency
  • Official group or organization compelled and authorized under statutes or law to control fires within a designated area or upon designated lands. 
Fire Behavior
  • The manner in which a fire reacts to the influences of fuel, weather, and topography. 
Fire Behavior Context
Fire Behavior Forecast
  • Prediction of probable fire behavior, usually prepared by a fire behavior analyst, in support of fire suppression or prescribed burning operations. 
Fire Behavior Prediction Model
  • A set of mathematical equations that can be used to predict certain aspects of fire behavior when provided with an assessment of fuel and environmental conditions. 
Fire Behavior Prediction System
  • A system that uses a set of mathematical equations to predict certain aspects of fire behavior in wildland fuels when provided with data on fuel and environmental conditions. 
Fire Benefits
  • Fire effects with positive monetary, social, or emotional value or that contribute, through changes in the resource base, to the attainment of organizational goals. 
Fire Bug
  • Arsonist, especially a repetitive firesetter. 
Fire Business
  • The characterization of fire occurrence in an area, described in terms of total number of fires and acres per year; and number of fires by time, size, cause, fire-day, large fire-day, and multiple fire-day. 
Fire Business Thresholds
  • Values of one or more fire weather/fire danger indexes that have been statistically related to occurrence of fires (fire business). Generally the threshold is a value, or range of values where historical fire activity has significantly increased or decreased. 
Fire Cache
  • A supply of fire tools and equipment assembled in planned quantities or standard units at a strategic point for exclusive use in fire suppression. 
Fire Cause
  • Agency or circumstance which started a fire or set the stage for its occurrence; source of a fire?s ignition. For statistical purposes fires are grouped into broad cause classes. The nine general causes used in the U.S. are lightning, campfire, smoking, debris burning, incendiary, machine use (equipment), railroad, children, and miscellaneous. 
Fire Cause Class
  • Any class into which wildland fires are grouped according to their origin. 
Fire Climate
  • Composite pattern of weather elements over time that affect fire behavior in a given region. 
Fire Climax
  • Plant community maintained by periodic fires. 
Fire Crew
  • General term for two or more firefighters organized to work as a unit. 
Fire Crew Work Formation
  • Standard crew arrangement used for fireline construction in direct or indirect attack; consists of line locator, line cutters, rakers, torch operators, and mop up crew. 
Fire Danger
  • Sum of constant danger and variable danger factors affecting the inception, spread, and resistance to control, and subsequent fire damage; often expressed as an index. 
Fire Danger Continuum
  • The range of possible values for a fire danger index or component, given a set of NFDRS parameters and weather input. 
Fire Danger Index
  • A relative number indicating the severity of wildland fire danger as determined from burning conditions and other variable factors of fire danger. 
Fire Danger Rating
  • A fire management system that integrates the effects of selected fire danger factors into one or more qualitative or numerical indices of current protection needs. 
Fire Danger Rating Area
  • A geographic area of relatively homogenous climate, fuels and topography, tens of thousands of acres in size, within which the fire danger can be assumed to be uniform. The basic on-the-ground unit for which unique fire management decisions are made based on fire danger ratings. Weather is represented by one or more NFDRS weather stations. 
Fire Danger Rating Operating Plan
  • A guide to collection, communication, and application of fire danger ratings at the local level. 
Fire Danger Rating PocketCard for Firefighter Safety
  • A communication aid designed to help firefighters develop an awareness of the local fire situation by providing a visual reference to fire danger rating. 
Fire Danger Rating System
  • The complete program necessary to produce and apply fire danger ratings, including data collection, data processing, fire danger modeling, communications, and data storage. 
Fire Day
  • Standard 24-hour period beginning at 1000 hours, during which most wildfires undergo a predictable speeding up and slowing down of intensity, depending primarily on the influence of weather and fuel factors. 
Fire Death
  • Fire casualty which is fatal or becomes fatal within one year of the fire. 
Fire Dependent
  • Plants and vegetation communities which have evolved adaptations such as a reliance on fire as a disturbance agent, protection as a species against the effects of wildland fire, or even a strengthening or enhancement by it. 
Fire Detection
  • Act or system of discovering and locating fires. 
Fire Diagram
Fire Discovery
  • The act of determining that a fire exists; does not include determining its location. 
Fire Ecology
  • The study of the effects of fire on living organisms and their environment. 
Fire Edge
  • The boundary of a fire at a given moment. 
Fire Education
  • Activities to change behaviors and attitudes about fire ecology, wildland fire and the role of fire in natural resource management. Defines the purposes for actions that provide information about and improve understanding of wildland fire. 
Fire Effects
  • The physical, biological, and ecological impacts of fire on the environment. 
Fire Environment
  • The surrounding conditions, influences, and modifying forces of topography, fuel, and weather that determine fire behavior. 
Fire Frequency
  • A general term referring to the recurrence of fire in a given area over time. 
Fire Front
  • The part of a fire within which continuous flaming combustion is taking place. Unless otherwise specified, the fire front is assumed to be the leading edge of the fire perimeter. In ground fires, the fire front may be mainly smoldering combustion. 
Fire Hazard
  • A fuel complex, defined by volume, type condition, arrangement, and location, that determines the degree of ease of ignition and of resistance to control. 
Fire Hazard Index
  • A numerical rating for specific fuel types, indicating the relative probability of fires starting and spreading, and the probable degree of resistance to control; similar to burning index, but without effects of wind speed. 
Fire Hazardous Areas
  • Those wildland areas where the combination of vegetation, topography, weather, and the threat of fire to life and property create difficult and dangerous problems. 
Fire History
Fire Information Retrieval and Evaluation System (FIRES)
  • A personal computer (PC) program that merges fire and weather/index files, and allows plotting and analysis of fire occurrence and fire danger. 
Fire Injury
  • Injury suffered as the result of a fire that requires (or should require) treatment by a practitioner of medicine within one year of the fire, regardless of whether treatment was actually received. 
Fire Inspector
  • Fire prevention specialist or arson investigator. 
Fire Interval
  • The number of years between two successive fire events for a given area; also referred to as fire-free interval or fire-return interval. 
Fire Investigation
  • The process of determining the ignition source, materials first ignited, ignition factors, and party responsible for a fire. 
Fire Lane
  • Cleared path wide enough to permit single-lane vehicular access in a remote area. 
Fire Load
  • The number and size of fires historically experienced on a given unit over a given period (usually one day) at a given index of fire danger. 
Fire Load Index (FLI)
  • Numerical rating of the maximum effort required to contain all probable fires occurring within a rating area during the rating period. 
Fire Management
  • All activities for the management of wildland fires to meet land management objectives. Fire management includes the entire scope of activities from planning, prevention, fuels or vegetation modification, prescribed fire, hazard mitigation, fire response, rehabilitation, monitoring and evaluation. 
Fire Management Area
  • One or more parcels of land having a common set of fire management objectives. 
Fire Management Improvements
  • All structures built and used primarily for fire management, e.g. lookout towers, lookout cabins, telephone lines, and also firebreaks, fuel breaks, and roads to lookouts. 
Fire Management Objective
  • Planned, measurable result desired from fire protection and use based on land management goals and objectives. 
Fire Management Plan (FMP)
Fire Management Unit (FMU)
  • A land area definable by specified management objectives, constraints, topographic features, access, values to be protected, political boundaries, fuel types, major fire regime groups, and other defined elements that set it apart from an adjacent area. The primary purpose of developing Fire Management Units in fire management planning is to assist in organizing information in complex landscapes. A fire management unit may have dominant management objectives and pre-selected strategies assigned to accomplish these objectives. 
Fire Pack
  • A one-person unit of fire tools, equipment, and supplies prepared in advance for carrying on the back. 
Fire Pattern
  • The visible or measurable physical changes formed by a fire effect or group of fire effects. This can be over a small area or it can include the overall pattern of fire spread as determined by the entirety of fire pattern indicators over a larger area. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
Fire Pattern Indicator
  • A physical object that displays changes (fire effects) from exposure to heat, flame, and combustion by-products that can reveal the direction of fire progression at a precise location with accurate analysis. A fire pattern indicator is a single component of the overall fire pattern. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412
Fire Pattern Indicator Cluster
Fire Pattern Indicator, Angle of Char
Fire Pattern Indicator, Angle of Scorch
Fire Pattern Indicator, Cupping
  • A concave or cup-shaped char pattern found on the side of fuels exposed to the oncoming fire including small stumps (generally 10 inch diameter and less are more reliable), grass stem ends and terminal ends of brush and tree limbs (generally less than 1/2 inch diameter) that indicate the direction of fire progression at that point. One of the 11 NWCG categories of fire pattern indicators. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
Fire Pattern Indicator, Curling
  • Green leaves and succulents, uncured vegetation which bends and curls inwards towards the heat source due to desiccation.  One of the 11 NWCG categories of fire pattern indicator. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
    • Definition Extension:  Typically found on vegetation that is lower to the ground in areas of lower intensity burning.
Fire Pattern Indicator, Foliage Freeze
  • Small branches, needles, and leaves swept into a position by the wind and fixed by desiccation indicating the wind direction at the time of fire passage. One of the 11 NWCG categories of fire pattern indicators. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
    • Definition Extension: Desiccation is the act of drying or becoming dry. 
Fire Pattern Indicator, Grass Stem
  • The un-consumed grass stems and heads of cured grass left lying on the ground after the passage of a fire that under certain circumstances point in the direction that the fire came from. One of the 11 NWCG categories of fire pattern indicators. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
    • Definition Extension: Typically found in areas of low intensity burning including but not limited to backing and lateral areas of fire progression. These indicators are typically missing from areas of high intensity burning where they are normally consumed.
Fire Pattern Indicator, Protection
  • A combustible or non-combustible object that displays differential damage or deposits on opposing sides due to the passage of the fire and indicates the direction of fire progression at that location.  One of the 11 NWCG categories of fire pattern indicators. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
Fire Pattern Indicator, Sooting
  • Objects displaying more soot deposits on the exposed surface of the object than on the protected surface of the object indicating the direction of fire progression at that location. One of the 11 NWCG categories of fire pattern indicators. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
Fire Pattern Indicator, Spalling (Exfoliation)
  • Rock or boulders that display more chipping or pitting on the exposed surface than the protected surface due to the passage of the fire indicating the direction of fire progression at that location. One of the 11 NWCG categories of fire pattern indicators. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
Fire Pattern Indicator, Staining
  • Objects displaying more stain deposits on the exposed surface of the object than on the protected surface of the object indicating the direction of fire progression at that location. One of the 11 NWCG categories of fire pattern indicators. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
Fire Pattern Indicator, U or V
Fire Pattern Indicator, White Ash
  • There are two subsets of the white ash fire pattern indicator, deposits and exposure.
    1. Objects displaying more white ash deposits on the exposed surface of the object as opposed to the protected surface of the object indicating the direction of fire progression at that location.
    2. Objects displaying more attached white ash on the exposed surface of the object as opposed to the protected surface of the object indicating the direction of fire progression at that location.
    One of the 11 NWCG categories of fire pattern indicators. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
Fire Perimeter
  • The entire outer edge or boundary of a fire. 
Fire Planning
  • The process of developing and interpreting goals and objectives necessary to guide wildland fire management actions.
    • Definition Extension: Process includes analysis and display of data and application of Laws, Policies, and Environmental Planning documents to wildland fire.
Fire Planning Unit (FPU)
  • The geographic scope of the landscape defined for the fire management analysis. A Fire Planning Unit consists of one or more Fire Management Units. FPUs may relate to a single administrative unit, a sub-unit, or any combination of units or sub-units. FPUs are scalable and may be contiguous or non-contiguous. FPUs are not predefined by agency administrative unit boundaries, and may relate to one or more agencies. They may be described spatially. 
Fire Plow
  • A heavy duty plowshare or disc plow usually pulled by a tractor to construct a fireline. 
Fire Potential
  • The likelihood of a wildland fire event measured in terms of anticipated occurrence of fire(s) and management's capability to respond. Fire potential is influenced by a sum of factors that includes fuel conditions (fuel dryness and/or other inputs), ignition triggers, significant weather triggers, and resource capability. 
Fire Presuppression
  • Activities undertaken in advance of fire occurrence to help ensure more effective fire suppression. Activities includes overall planning, recruitment and training of fire personnel, procurement and maintenance of firefighting equipment and supplies, fuel treatment and creating, maintaining, and improving a system of fuel breaks, roads, water sources, and control lines. 
Fire Prevention
  • Activities such as public education, community outreach, law enforcement, engineering, and reduction of fuel hazards that are intended to reduce the incidence of unwanted human-caused wildfires and the risks they pose to life, property or resources. 
Fire Progress Map
  • A map maintained on a large fire to show at given times the location of the fire, deployment of suppression forces, and progress of suppression. 
Fire Progression
Fire Qualifications
  • Computerized interagency summary of fire suppression qualifications of listed personnel. Available information includes fire training record, fire experience record, and physical fitness testing score for each individual. 
Fire Regime
  • Description of the patterns of fire occurrences, frequency, size, severity, and sometimes vegetation and fire effects as well, in a given area or ecosystem. A fire regime is a generalization based on fire histories at individual sites. Fire regimes can often be described as cycles because some parts of the histories usually get repeated, and the repetitions can be counted and measured, such as fire return interval. 
Fire Regime Current Condition Class
  • A qualitative measure classified into three classes describing the relative degree of departure from historical fire regimes, possibly resulting in alterations of key ecosystem components such as species composition, structural stage, stand age, canopy closure, and fuel loadings. 
Fire Regime Groups
  • A classification of fire regimes into a discrete number of categories based on frequency and severity. The national, coarse-scale classification of fire regime groups commonly used includes five groups: I - frequent (0-35 years), low severity; II - frequent (0-35 years), stand replacement severity; III - 35-100+ years, mixed severity; IV - 35-100+ years, stand replacement severity; and V - 200+ years, stand replacement severity. 
Fire Report
  • An official record of a fire, generally including information on cause, location, action taken, damage, costs, etc., from start of the fire until completion of suppression action. These reports vary in form and detail from agency to agency. 
Fire Resistant Tree
  • A species with compact, resin-free, thick corky bark and less flammable foliage that has a relatively lower probability of being killed or scarred by a fire than a fire sensitive tree. 
Fire Resources
  • All personnel and equipment available or potentially available for assignment to incidents. 
Fire Retardant
  • Any substance except plain water that by chemical or physical action reduces flammability of fuels or slows their rate of combustion. 
Fire Risk
  1. The chance of fire starting, as determined by the presence and activity of causative agents.
  2. A causative agent.
  3. A number related to the potential number of firebrands to which a given area will be exposed during the rating day (National Fire Danger Rating System). 
Fire Scar
  1. A healing or healed injury or wound to woody vegetation, caused or accentuated by a fire.
  2. The mark left on a landscape by fire. 
Fire Scar Analysis
  • Analysis of one or more fire scars to determine individual tree fire frequency or mean fire intervals for specified areas. 
Fire Season
  1. Period(s) of the year during which wildland fires are likely to occur, spread, and affect resources values sufficient to warrant organized fire management activities.
  2. A legally enacted time during which burning activities are regulated by federal, state or local authority. 
Fire Sensitive Tree
  • A species with thin bark or highly flammable foliage that has a relatively greater probability of being killed or scarred by a fire. 
Fire Severity
  • Degree to which a site has been altered or disrupted by fire; loosely, a product of fire intensity and residence time. 
Fire Shelter
  • An aluminized cloth tent that offers protection in a fire entrapment situation by reflecting radiant heat and providing a volume of breathable air.

    • Definition Extension:  Fire shelters are not a fail-safe. Firefighters should avoid situations where a fire shelter is needed, but they are trained to deploy it if they cannot escape and feel the shelter is needed for protection from heat, smoke, and/or ember showers.

Fire Shelter Deployment
  • Removing a fire shelter from its case and unfolding it to use as protection against heat, smoke, and burning embers.

    • Definition Extension:  Shelter deployments can be categorized as:  1)  Life Saved - Saved the life of the firefighter; 2) Injury Prevented - Prevented burns and/or smoke inhalation to the firefighter; 3) Precautionary - Deployed in a situation with perceived potential danger. The environment did not materialize into a situation where the firefighter would have been killed or injured without the use of a fire shelter; 4) Fatality - Fatality occurred in a fully or partially deployed fire shelter.

Fire Shelter Deployment Site
  • Immediate area where a fire shelter has been deployed.
Fire Shovel
  • Type of shovel specifically designed for use in constructing a fireline; has a tapered blade with both edges sharpened for scraping, digging, grubbing, cutting, and throwing. 
Fire Simulator
  • Training device that imposes simulated fire and smoke on a landscape image, for the purpose of instructing fire suppression personnel in different fire situations and fire suppression techniques. 
Fire Sketch
Fire Spread Model
  • A set of physics and empirical equations that form a mathematical representation of the behavior of fire in uniform wildland fuels. 
Fire Storm
  • Violent convection caused by a large continuous area of intense fire. Often characterized by destructively violent surface indrafts, near and beyond the perimeter, and sometimes by tornado-like whirls.
Fire Suppressant
  • Any agent used to extinguish the flaming and glowing phases of combustion by direct application to the burning fuel. 
Fire Suppression
  • All work and activities connected with control and fire-extinguishing operations, beginning with discovery and continuing until the fire is completely extinguished. 
Fire Suppression Organization
  1. The personnel and equipment collectively assigned to the suppression of a specific fire or group of fires.
  2. The personnel responsible for fire suppression within a specified area.
  3. The management structure, usually shown in the form of an organization chart of the persons and groups having specific responsibilities in fire suppression. 
Fire Swatter
  • A fire tool that consists of a thick, flat piece of rubber on a long handle used to drag over or smother out flames of grass fires. 
Fire Tool Cache
  • A supply of fire tools and equipment assembled in planned quantities or standard units at a strategic point for exclusive use in wildland operations. 
Fire Trap
  1. An accumulation of highly combustible material, rendering firefighting dangerous.
  2. Any situation in which it is highly dangerous to fight fire. 
Fire Treatment
  • The use of fire to accomplish a specified objective. 
Fire Triangle
  • Instructional aid in which the sides of a triangle are used to represent the three factors (oxygen, heat, fuel) necessary for combustion and flame production; removal of any of the three factors causes flame production to cease. 
Fire Type
  • A management distinction, made to satisfy legal and budget constraints, based on whether the ignition source was planned or unplanned. Under the implementation guidance, only two types of wildland fire - wildfire and prescribed fire - are recognized. 
Fire Vector
Fire Weather
  • Weather conditions which influence fire ignition, behavior, and suppression. 
Fire Weather Forecast
  • A weather prediction specially prepared for use in wildland fire operations and prescribed fire. 
Fire Weather Index (FWI)
  • A numerical rating in the Canadian fire danger rating system, based on meteorological measurements of fire intensity in a standard fuel type. (The standard fuel type is representative of jack pine and lodgepole pine.) The FWI is comprised of three fuel moisture codes, covering classes of forest fuel of different drying rates, and two indices that represent rate of spread and the amount of available fuel. 
Fire Weather Station
  • A meteorological station specially equipped to measure weather elements that have an important effect on fire behavior. 
Fire Weather Watch
  • A Fire Weather Watch is issued to advise of conditions which could result in extensive wildland fire occurrence or extreme fire behavior, which are expected to develop in the next 12 to 48 hours, but not more than 72 hours. In cases of dry lightning, a Fire Weather Watch may be issued for the next 12 hours. 
Fire Whirl
  • Spinning vortex column of ascending hot air and gases rising from a fire and carrying aloft smoke, debris, and flame. Fire whirls range in size from less than one foot to over 500 feet in diameter. Large fire whirls have the intensity of a small tornado. 
Fire-flood Cycle
  • The greatly increased rate of water run off and soil movement from steep slopes that may follow removal of the vegetative cover by burning. 
  • Removal or treatment of fuels to reduce the danger of fires igniting or spreading. (E.g., fire-proofing roadsides, campsites, structural timber.) Protection is relative, not absolute. 
  • Any source of heat, natural or human made, capable of igniting wildland fuels. Flaming or glowing fuel particles that can be carried naturally by wind, convection currents, or by gravity into unburned fuels. 
  • A natural or constructed barrier used to stop or check fires that may occur, or to provide a control line from which to work. 
  • Set of computerized FIREMODELS run during fire season at the operations coordination center on preselected locations to indicate possible fire spread from those points for that date. 
  • Unique code (alpha-numeric) assigned to wildland fires. One FireCode project number per fire is assigned for use by all five federal wildland firefighting agencies. Fire codes may be any combination of four-digit alpha-numeric characters. Each agency's finance community incorporates the FireCode project number into the accounting code. 
FIREFAMILY (Fire Data Program)
  • A computer program that uses historical weather and fire data for fire planning. Its three major routines are FIRDAT, SEASON, and FIRINF. 
FireFamily Plus
  • A software application that provides summaries of fire weather/danger climatology and occurrence for one or more weather stations extracted from NIFMID. 
Firefighting Forces
  • Qualified firefighters, together with their equipment and material, used to suppress wildland fires. 
Firefighting Technology Implementation Program (FIRETIP)
  • A computer program through which the technology of FIRESCOPE is transferred to areas outside southern California, where complex, multi-agency fires and other incidents commonly occur. 
  • Operational area on which firefighters combat a fire. 
Firelamp (Fire and Land Management Planning)
  • Computerized multi-resource model that simulates the effects that naturally caused prescribed fires have on the future production of natural resources such as timber, forage, wildlife, recreation, and water. 
  1. The part of a containment or control line that is scraped or dug to mineral soil. 
  2. For purposes of pay administration for hazardous duty, a fireline is defined as the area within or adjacent to the perimeter of an uncontrolled wildfire of any size in which action is being taken to control fire. Such action includes operations, which directly support control of fire (e.g. activities to extinguish the fire, ground scouting, spot fire patrolling, search and rescue operations, and backfiring).
Fireline Explosives (FLE)
  • Specially developed coils containing explosive powder that are detonated to create a fireline through ground fuels. 
Fireline Intensity
  1. The product of the available heat of combustion per unit of ground and the rate of spread of the fire, interpreted as the heat released per unit of time for each unit length of fire edge. The primary unit is Btu per second per foot (Btu/sec/ft) of fire front.
  2. The rate of heat release per unit time per unit length of fire front. Numerically, it is the product of the heat yield, the quantity of fuel consumed in the fire front, and the rate of spread. 
  • Computer program which with specified information (fuel, weather, topography) predicts an hourly rate of spread from a point of origin. 
  • Person who starts a fire, usually deliberately and maliciously. 
  • Starting a fire, usually deliberately and maliciously. 
Firing Out
  • The act of setting fire to unburned fuels located between the control line and main fire in burning out operations. 
Firing Technique
  • Any method or pattern of igniting a wildland area to consume the fuel in a prescribed pattern. E.g., heading or backing fire, spot fire, strip-head fire, and ring fire. 
First Aid
  • Emergency care or treatment given to an ill or injured person before regular medical care can be obtained. First aid is generally provided by someone other than a physician. On incidents, most first aid is provided in the field or camp by medical unit personnel such as Emergency Medical Technicians (EMT).
First Fuel Ignited
First Order Fire Effects (FOFE)
  • The effects that concern the direct or immediate consequences of fire, such as biomass consumption, crown scorch, bole damage, and smoke production. First order effects form an important basis for predicting secondary effects such as tree regeneration, plant succession, and changes in site productivity, but these involve interaction with many other non-fire variables. 
  • Firefighters initially attacking a fire, usually the first to arrive at the fire scene. 
  • Geographical position determined by visual reference to the surface, by reference to one or more radio navigational aids, by celestial plotting, or by any other navigational device. 
Fixed Tank
  • A device mounted inside or directly underneath an aircraft which can contain water or retardant for dropping onto a fire. 
  1. A mass of gas undergoing rapid combustion, generally accompanied by evolution of sensible heat and incandescence.
  2. Light given off by burning gasses during the combustion process. 
Flame Angle
  • Angle between the flame at the leading edge of the fire front and the ground surface, expressed in degrees. 
Flame Depth
  • The depth of the fire front. 
Flame Height
  • The average maximum vertical extension of flames at the leading edge of the fire front. Occasional flashes that rise above the general level of flames are not considered. This distance is less than the flame length if flames are tilted due to wind or slope. 
Flame Length
  • The distance between the flame tip and the midpoint of the flame depth at the base of the flame (generally the ground surface), an indicator of fire intensity. 
Flame Thrower
Flaming Combustion Phase
  • Luminous oxidation of gases evolved from the rapid decomposition of fuel. This phase follows the pre-ignition phase and precedes the smoldering combustion phase, which has a much slower combustion rate. Water vapor, soot, and tar comprise the visible smoke. Relatively efficient combustion produces minimal soot and tar, resulting in white smoke; high moisture content also produces white smoke. 
Flaming Front
  • That zone of a moving fire where the combustion is primarily flaming. Behind this flaming zone combustion is primarily glowing or involves the burning out of larger fuels (greater than about 3 inches in diameter). Light fuels typically have a shallow flaming front, whereas heavy fuels have a deeper front.
Flaming Phase
  • That phase of a fire where the fuel is ignited and consumed by flaming combustion. 
  • The relative ease with which fuels ignite and burn regardless of the quantity of the fuels. Preferred to "inflammability."
  • Easily ignitable and capable of burning and producing flames. 
Flammable liquid
  • A liquid generally with a flash point below 140F (60C) and a vapor pressure that does not exceed 40 PSI at 100F (37.8C). 
Flank Fire
  • A firing technique consisting of treating an area with lines of fire set into the wind which burn outward at right angles to the wind. 
Flanking Fire Suppression
  • Attacking a fire by working along the flanks either simultaneously or successively from a less active or anchor point and endeavoring to connect two lines at the head. 
Flanks of a Fire
  • 1) The parts of a fire's perimeter that are roughly parallel to the main direction of spread. 2) The parts of a fire’s perimeter that are roughly parallel to the main direction of fire spread. 
  • Fire suppression tool, sometimes improvised, used in direct attack for smothering out flames along a fire edge; may consist merely of a green pine bough or wet sacking, or be a manufactured tool such as a flap of belting fabric fastened to a long handle. 
  • Any sudden acceleration in rate of spread or intensification of the fire. Unlike blowup, a flare-up is of relatively short duration and does not radically change existing control plans. 
Flash Fuels
  • Highly combustible fine fuels such as grass, leaves, draped pine needles, fern, tree moss and some kinds of slash, which ignite readily and are consumed rapidly when dry. 
Flash Point
  • Lowest temperature at which the vapor of a combustible liquid can be made to ignite in air. 
  1. Rapid combustion and/or explosion of unburned gases trapped at some distance from the main fire front. Usually occurs only in poorly ventilated topography.
  2. Stage of a fire at which all surfaces and objects within a space have been heated to their ignition temperature, and flame breaks out almost at once over the surface of all objects within the space. 
Flight Crew Member
  • An individual holding a valid Federal Aviation Administration (FAA) Airman’s Certificate and flight physical as a prerequisite to performance of the duties of the position during flight: e.g., Pilot, co-Pilot, flight engineer, or flight navigator.   Source: NWCG Standards for Helicopter Operations, PMS 510.
Flight Following
  • The method and process through which an aircraft is tracked from departure point to destination. Flight following is the knowledge of the aircraft location and condition at regular intervals with a reasonable degree of certainty such that, in the event of mishap, those on board may be rescued. 
Flight Path
  1. Track of an aircraft over the earth's surface.
  2. Specified information relating to the intended flight of an aircraft that is filed orally or in writing with an air traffic control facility. 
Flight Time
  • The time from the moment the aircraft first moves under its own power for the purpose of flight until the moment it comes to rest at the next point of landing. 
Flight Visibility
  • Average forward horizontal distance from the cockpit of an aircraft in flight at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night. 
Floatable Pump
  • Small portable pump that floats in the water source. 
Flow Conditioner
  • Chemical powders that will, in very small quantities, tend to prevent other powders from caking and flocculating. Imparts free-flowing qualities to powder. Used with fire retardant chemicals. 
Fluid Foam
  • A low expansion foam type with some bubble structure and moderate drain time, exhibiting properties of both wet and dry foam types, which is used for extinguishment, protection, and mopup. 
Fly Ash
  • Particulate matter emitted by a fire and larger than 10 microns in diameter with a consequently short residence time in the atmosphere. 
  • The aerated solution created by forcing air into, or entraining air in water containing a foam concentrate by means of suitably designed equipment or by cascading it through the air at a high velocity. Foam reduces combustion by cooling, moistening and excluding oxygen. 
Foam Blanket
  • A layer of foam which forms an insulating and reflective barrier to heat and is used for fuel protection, suppression, and mopup. 
Foam Concentrate
  • The concentrated foaming agent as received from the manufacturer which, when added to water, creates a foam solution; use only those approved for use in wildland fire situations by the authority having jurisdiction. 
Foam Generation
  • The foam production process of forcing air into or entraining air in foam solution, creating a mass of bubbles. 
Foam Line
  • A body of foam placed along areas to be protected from fire; also used as an anchor for indirect attack in place of hand-made fire line. 
Foam Solution
  • A low expansion foam type with no expansion, therefore lacking bubble structure, which is used for mopup and flame knock down. 
Foam Systems
  • The apparatus and techniques used to mix concentrate with water to make solution, pump and mix air and solution to make foam, and transport and apply foam. (Systems defined here include compressed air foam and nozzle aspirated.) 
Foam Type
  • A term used to describe the consistency and viscosity of low expansion foam as the combination of drain time and expansion. 
Foaming Agent
  • An additive that reduces the surface tension of water (producing wet water) causing it to spread and penetrate more effectively and which produces foam through mechanical means. 
Foehn Wind
  • A warm, dry and strong general wind that flows down into the valleys when stable, high pressure air is forced across and then down the lee slopes of a mountain range. The descending air is warmed and dried due to adiabatic compression producing critical fire weather conditions. Locally called by various names such as Santa Ana winds, Devil winds, North winds, Mono winds, etc. 
Folding Tank
  • A portable, collapsible water tank with a tubular frame. Tank capacities vary in size from 500-1500 gallons. 
Food Unit
  • Functional unit within the Logistics Section responsible for providing meals for incident personnel. 
  • A plant with an herbaceous (soft, rather than permanent woody) stem, that is not a grass or grasslike plant. 
Forced Landing
  • Landing necessitated by failure of engines, systems, or components which makes continued flight impossible and which may not result in damage. 
Forcible Entry
  • Entering a structure of vehicle illegally by means or physical force, often characterized by prying doors and breaking windows. 
Forecast Area
  • Geographical area for which a fire weather forecast is specified. 
Forest Planning Language and Simulator (FORPLAN)
  • Computer program developed to facilitate the use of simulation for integrating many different resource management activities, including fire, into the land management planning process. FORPLAN incorporates unique characteristics of previous systems, links numerous models and data bases, allows selection of variable resolution levels, and permits discrete time simulation of disturbances on plants, fuels, and animals. 
Forest Residue
  • Accumulation in the forest of living or dead (mostly woody) material that is added to and rearranged by human activities such as harvest, cultural operations, and land clearing. 
Forestry Weather Information System (FWIS)
  • A real time system which takes observations and forecasts supplied by NWS in coded numeric form, reformats that input by computer based algorithms, and distributes the reformatted information as numeric and worded diagnoses and forecasts for specialized users in localized areas. 
Forward Looking Infrared (FLIR)
  • Hand held or aircraft mounted device designed to detect heat differentials and display their images on a video screen. FLIRs have thermal resolution similar to IR line scanners, but their spatial resolution is substantially less; commonly used to detect hotspots and flareups obscured by smoke, evaluate the effectiveness of firing operations, or detect areas needing mopup. 
Forward Rate of Spread
  • The speed with which a fire moves in a horizontal direction across the landscape, usually expressed in chains per hour or feet per minute. 
Fragile Fire Cause Objects
  • Objects that are easily susceptible to damage from head and flame and can be easily damaged or destroyed by suppression action and/or during the evidence collection process. E.g., cigarette ash. 
Free Burning
  • The condition of a fire or part of a fire that has not been slowed by natural barriers or by control measures. 
Free Drop
  • Cargo, not attached to a parachute, that is dropped intentionally from an aircraft in flight. 
Free Flow (Hydraulics)
  • Maximum water flow rate a fire pump will attain when there are no restrictions at the pump outlet or losses due to friction or head. 
Freezing Rain
  • Rain that freezes upon contact with objects on the ground. 
Friction Layer
  • The layer of the atmosphere in which the frictional force of the earth?s surface exercises an appreciable influence on winds. 
Friction Loss
  • Pressure loss caused by the movement of water or solution against the interior surface of fire hose, pipe, or fittings; normally measured in pressure loss per length of hose or pipe. 
Friction Reducing Agent (FRA)
  • Water soluble substance that reduces frictional drag of solutions and dampens turbulent flow while being pumped through pipe or hose. 
  • In meteorology, the boundary between two air masses of differing atmospheric properties. 
  • Crystals of ice formed and deposited like dew, but at a temperature below freezing. 
  • In the 1978 version of NFDRS, the herbaceous stage when cold temperatures kill herbaceous plants and force woody fuels into dormancy. 
  • Any combustible material, especially petroleum-based products and wildland fuels. 
Fuel Arrangement
  • A general term referring to the spatial distribution and orientation of fuel particles or pieces. 
Fuel Bed
  • An array of fuels usually constructed with specific loading, depth, and particle size to meet experimental requirements; also, commonly used to describe the fuel composition. 
Fuel Bed Depth
  • Average height of surface fuels contained in the combustion zone of a spreading fire front. 
Fuel Break
  • A natural or manmade change in fuel characteristics which affects fire behavior so that fires burning into them can be more readily controlled. 
Fuel Break System
  • A series of modified strips or blocks tied together to form continuous strategically located fuel breaks around land units. 
Fuel Characteristics
  • Factors that make up fuels such as compactness, loading, horizontal continuity, vertical arrangement, chemical content, size and shape, and moisture content. 
Fuel Class
  • Part of the National Fire Danger Rating System (NFDRS). Group of fuels possessing common characteristics. Dead fuels are grouped according to 1-, 10-, 100-, and 1000-hour timelag, and living fuels are grouped as herbaceous (annual or perennial) or woody. 
Fuel Condition
  • Relative flammability of fuel as determined by fuel type and environmental conditions. 
Fuel Continuity
  • The degree or extent of continuous or uninterrupted distribution of fuel particles in a fuel bed thus affecting a fire's ability to sustain combustion and spread. This applies to aerial fuels as well as surface fuels. 
Fuel Depth
  • The average distance from the bottom of the litter layer to the top of the layer of fuel, usually the surface fuel.
Fuel Dryness Level (DL)
  • A quantitative measure of fuel moisture and receptability to ignition as determined by an accepted Fire Danger Rating System index that influences fire growth, intensity, or activity. 
Fuel Group
  • An identifiable association of fuel elements of distinctive species, form, size, arrangement, or other characteristics. General fuel groups are grass, brush, timber, and slash. 
Fuel Loading
  • The amount of fuel present expressed quantitatively in terms of weight of fuel per unit area. This may be available fuel (consumable fuel) or total fuel and is usually dry weight. 
Fuel Management
  • Act or practice of controlling flammability and reducing resistance to control of wildland fuels through mechanical, chemical, biological, or manual means, or by fire, in support of land management objectives. 
Fuel Model
  • Simulated fuel complex for which all fuel descriptors required for the solution of a mathematical rate of spread model have been specified. 
Fuel Modification
  • Manipulation or removal of fuels to reduce the likelihood of ignition and/or to lessen potential damage and resistance to control (e.g., lopping, chipping, crushing, piling and burning). 
Fuel Moisture Analog
  • Device that emulates the moisture response of specific classes of dead fuels, constructed from organic or inorganic materials (e.g., half-inch ponderosa pine dowels representing ten-hour timelag fuels). 
Fuel Moisture Content
  • The quantity of moisture in fuel expressed as a percentage of the weight when thoroughly dried at 212 degrees F. 
Fuel Moisture Indicator Stick
  • A specially prepared stick or set of sticks of known dry weight continuously exposed to the weather and periodically weighed to determine changes in moisture content as an indication of moisture changes in wildland fuels. 
Fuel Reduction
  • Manipulation, including combustion, or removal of fuels to reduce the likelihood of ignition and/or to lessen potential damage and resistance to control. 
Fuel Size Class
  • A category used to describe the diameter of down dead woody fuels. Fuels within the same size class are assumed to have similar wetting and drying properties, and to preheat and ignite at similar rates during the combustion process. 
Fuel Temperature
  • The temperature reading measured from a fuel stick fully exposed to sunlight, above a representative fuel bed, using one of two methods (within a 3/4-inch or across a 1/2-inch pine dowel). 
Fuel Tender
  • Any vehicle capable of supplying engine fuel to ground or airborne equipment. 
Fuel Treatment
  • Manipulation or removal of fuels to reduce the likelihood of ignition and/or to lessen potential damage and resistance to control (e.g., lopping, chipping, crushing, piling and burning). 
Fuel Type
  • An identifiable association of fuel elements of distinctive species, form, size, arrangement, or other characteristics that will cause a predictable rate of spread or resistance to control under specified weather conditions. 
Fuels Wet Flag
  • A one-character code indicating whether or not fine fuels are wet or dry. 
Fugitive Color
  • A coloring agent used in fire retardants that is designed to fade rapidly following retardant application in order to minimize the visual impacts of the retardant. 
Full-thickness Burn
  • A burn involving all the layer of the skin. Muscle layers below the skin and bones may also be damaged. Areas of the skin may be charred black or areas that are dry and white (also called Third Degree Burn).
  • An airborne irritating, noxious, or toxic smoke, vapor, or any combination of these produced by a volatile substance or a chemical reaction. 
  • In ICS, function refers to the five major activities: command, operations, planning, logistics and finance/administration. 
  • A colored flare designed as a railway warning device, widely used to ignite backfires and other prescribed fires.
Gallons per Minute (GPM)
  • The measure of water flow in firefighting. It is used to measure the output of wildland and structural fire engines, pumps, hose streams, nozzles, hydrants, and water mains. 
  • Weak or missed area in a retardant drop or in a fireline. 
Gate Valve
  • A valve with a gate-like disk that moves up and down at right angles to the flow when actuated by a stem screw and hand wheel. Gate valves are best for service that requires infrequent valve operation and where the disk is kept either fully open or closed. 
Gear Pump
  • Positive displacement pump which uses closely meshed gears to propel water when high pressures and low volumes are desired; can be used safely only with clear water-- suspended particles of soil or rocks can quickly wear the gears and reduce pressure and volume of water. 
General Fire Weather Forecast
  • A forecast, issued daily during the regular fire season to resource management agencies, that is intended for planning of daily fire management activities, including daily staffing levels, prevention programs, and initial attack on wildfires. Also called presuppression forecast. 
General Origin Area (GOA)
  • The larger area where the fire first established itself and is identified by an analysis of the fire behavior context, macroscale fire pattern indicators, and witness statements. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
    • Definition Extension: The general origin area includes within its boundary the specific origin area and ignition area and is typically less than ½ acre in size.     
General Schedule Employee
  • A regular federal government employee who is compensated under the General Schedule (GS) Pay Plan.
General Staff
  • The group of incident management personnel reporting to the Incident Commander. They may each have a deputy, as needed. The General Staff consists of: Operations Section Chief, Planning Section Chief, Logistics Section Chief, and Finance/Administration Section Chief. 
General Winds
  • Large scale winds caused by high- and low-pressure systems but generally influenced and modified in the lower atmosphere by terrain. 
Geographic Area
  • A boundary designated by governmental agencies (wildland fire protection agencies) within which they work together for the interagency, intergovernmental planning, coordination, and operations leadership for the effective utilization of emergency management resources within their area. There are nine geographic areas. A listing of the areas can be found in the National Interagency Mobilization Guide, Chapter 70 along with listings of the Geographic Coordinating Areas and Geographic Area Coordination Centers. 
Geographic Area Coordinating Group (GACG)
  • An interagency body of fire management representatives from each federal and state land management agency within a nationally recognized regional area that provides leadership and support to facilitate safe and efficient fire management activities. Working collaboratively, a GACG's mission is not only for wildland fire emergencies, but for other emergency incidents, as necessary.
Geographic Area Coordination Center (GACC)
  • The physical location of an interagency, regional operation center for the effective coordination, mobilization and demobilization of emergency management resources. A coordination center serves federal, state and local wildland fire agencies through logistical coordination of resources throughout the geographic area, and with other geographic areas, as well. Listings of geographic coordination centers and their respective geographic coordinating areas can be found within the National Interagency Mobilization Guide. 
Geographic Coordinating Area
  • A boundary designated by governmental agencies (wildland fire protection agencies), that may coincide with a geographic area boundary or may be a subdivision of a geographic area within which they work together coordinating, for the effective, mobilization and demobilization of emergency management resources within their area. Listings of geographic coordinating areas and geographic coordination centers can be found in the National Interagency Mobilization Guide, Chapter 20, Section 21.1. 
Geostationary Operational Environmental Satellite (GOES)
Getaway Time
  • Elapsed time from receipt of notification by the personnel charged with initiating suppression action to the departure of the first attack unit. 
Global Positioning System (GPS)
  • A system of navigational satellites operated by the U.S. Department of Defense and available for civilian use. The system can track objects anywhere in the world with an accuracy of approximately 40 feet. 
Glowing Combustion
  • The process of oxidation of solid fuel accompanied by incandescence. All volatiles have already been driven off, oxygen reaches the combustion surfaces, and there is no visible smoke. This phase follows the smoldering combustion phase and continues until the temperature drops below the combustion threshold value, or until only non-combustible ash remains. 
Glowing Combustion Phase
  • The final phase of combustion following flaming and smoldering phases. 
Going Fire
  • Any wildfire on which suppression action has not reached an extensive mop up stage. 
Government Vehicle
  • A vehicle owned by, on loan to, leased or rented by the government.
Gradient Wind
  1. Wind flowing parallel to pressure isobars or contours with low pressure on the left of the observer in the Northern Hemisphere; velocity such that the pressure gradient, Coriolis, and centrifugal force acting in the area are in balance.
  2. Wind created by differing barometric pressures between high- and low-pressure systems. Velocity is generally five to 30 miles per hour, and wind shifts are usually gradual as systems move and shift. 
Grass Fire
  • Any fire in which the predominant fuel is grass or grasslike. 
Grass Type
  • In NFDRS, the two grass types (annual, perennial) determine how seasonal drying of live herbaceous fuels is modeled. 
  • Of, or pertaining to, measurement by weight. 
Gravity Tank
  • Water storage tank for fire protection and sometimes community water service that supplies water by gravity pressure. 
  • Green-up for the 1978 version of NFDRS model is defined as the beginning of a new cycle of plant growth. Green-up usually occurs once a year, except in desert areas where rainy periods can produce a flush of new growth more than once a year. Green-up may be signaled at different dates for different fuel models. Green-up should not be started when the first flush of green occurs in the area. Instead, the vegetation that will be the fire problem (represented by the NFDRS fuel model associated with the weather station) when it matures and cures should be identified. Green-up should start when the majority of this vegetation starts to grow. 
  • Landscaped and regularly maintained fuel break, usually put to some additional use (e.g., golf course, park, playground). 
Greenhouse Effect
  • The heating of the earth's surface by both atmospheric infrared radiation and incoming solar radiation. 
Greenness Factor
  • In the 1988 version of NFDRS, a code scaled from 0 to 20 representing the greenness of grasses and shrubs from near dead to maximum greenness. 
Grid Ignition Technique
  • Method of igniting prescribed fires in which ignition points are set individually at predetermined spacing with predetermined timing throughout the area to be burned. Also called point source ignition technique. 
Grid Search Technique
  • To search for a small fire by systematically traveling over an area on parallel courses or gridlines. 
Gross Axle Weight Rating (GAWR)
  • The value specified by the manufacturer as the maximum allowable weight placed on an axle of a vehicle when fully equipped, including payload, fluids and occupants. 
Gross Vehicle Weight (GVW)
  • Actual vehicle weight, including chassis, body, cab, equipment, water, fuel, crew, and all other load. 
Gross Vehicle Weight Rating (GVWR)
  • The value specified by the manufacturer as the maximum allowable weight of a vehicle fully equipped, including payload, fluids and occupants. 
Gross Weight
  • Total allowable weight of a loaded aircraft for takeoff or landing, adjusted for altitude differences. 
Ground Effect
  • Reaction of a rotor downdraft against the ground surface, forming a "ground cushion" that increases lifting capability of that section of air.
Ground Fire
  • Fire that consumes the organic material beneath the surface litter ground, such as a peat fire. 
Ground Fog
  • Fog which extends vertically to less than 20 feet. 
Ground Fuel
  • All combustible materials below the surface litter, including duff, tree or shrub roots, punky wood, peat, and sawdust, that normally support a glowing combustion without flame. 
Ground Speed
  • Speed with which an aircraft traverses the ground over which it flies. 
Ground Support Unit
  • Functional unit within the Logistics Section responsible for the fueling, maintaining and repairing of vehicles, and the transportation of personnel and supplies. 
Ground Truth
  • Verification at the site of what has been observed and/or measured from aircraft, satellites, other aerial platforms, aerial photographs, or maps. 
Ground Visibility
  • Horizontal visibility observed at the ground. 
  • Groups are established to divide the incident into functional areas of operation. Groups are composed of resources assembled to perform a special function not necessarily within a single geographic division. Groups, when activated, are located between branches and resources in the operations section. 
Growing Season Burning
  • Prescribed burning or use of wildland fire during the photosynthetically-active growing season, where live fuel moistures are relatively high and the dominant vegetation, grasses, forbs, and herbaceous vegetation are fully greened. 
Gum Thickened Sulphate (GTS)
  • A dry chemical product which is mixed with water to form a fire retardant slurry. 
  • Rapid fluctuations in wind speed with a variation of 10 knots (11.5 mph) or more between peaks and lulls. 
Haines Index
  • An atmospheric index used to indicate the potential for wildfire growth by measuring the stability and dryness of the air over a fire. 
Hand Crew
  • A number of individuals that have been organized and trained and are supervised principally for operational assignments on an incident. 
  • Fireline constructed with hand tools. 
Hangup (Tree Falling)
  • A situation in which a tree is lodged in another, preventing it from falling to the ground. 
Hard Suction Hose
  • Noncollapsible suction hose attached to a pump and used to draft water from a source lower than the pump. Customary hose sizes in wildland fire engines are 2 and 2-1/2 inches in diameter (51 and 64 mm). 
  • Any real or potential condition that can cause injury, illness or death of personnel, or damage to, or loss of equipment or property. 
Hazard Assessment
  • Assess hazards to determine risks. Assess the impact of each hazard in terms of potential loss, cost, or strategic degradation based on probability and severity. 
Hazard Fuel
  • A fuel complex defined by kind, arrangement, volume, condition, and location that presents a threat of ignition and resistance to control. 
Hazard Map
  • Map of the area of operations that shows all of the known aerial hazards, including but not limited to power lines, military training areas, hang gliding areas, etc. 
Hazard Pay
  • A salary differential that compensates employees for exposure to hazards in the course of their duties. 
Hazard Reduction
  • Any treatment of living and dead fuels that reduces the potential spread or consequences of fire. 
Hazardous Areas
  • Those wildland areas where the combination of vegetation, topography, weather, and the threat of fire to life and property create difficult and dangerous problems. 
Hazardous Materials
  1. Substances that are identified, classified, and regulated in the Code of Federal Regulations, Title 49 and Hazardous Materials Regulations 175.
  2. A substance or material which has been determined by the Secretary of Transportation to be capable of posing an unreasonable risk to health, safety, and property when transported in commerce and which has been so designated. 
  • A sufficient concentration of atmospheric aerosols to affect a visible attenuation of light and measurable reduction in visual range. The aerosol particle diameter is near the wavelength of visible light, optimizing the light scattering efficiency of the particles. 
Haze Meter
  • Instrument for measuring the dependable range of distance at which a standard smoke column can be detected by the unaided eye under existing haze conditions. 
Head Fire
  • A fire spreading or set to spread with the wind. 
Head of the Fire
Head Pressure
  • Pressure due to elevation of water. Equals 0.433 pounds per square inch (PSI) per foot of elevation. (Approximately 0.5 PSI is required to lift water 1 foot in elevation) 
  • The compass direction in which the longitudinal axis of the aircraft points. 
  • Flashlight, ordinarily worn by firefighter on the front of the helmet. 
  • Temperatures higher than that of the normal atmosphere, produced by the process of burning or oxidation. 
Heat Content
  • The net amount of heat that would be given off if fuel burns when it is absolutely dry, noted as Btu per pound of fuel. 
Heat Low
  • An area of low pressure caused by intense heating of the earth's surface. High surface temperature causes air to expand and rise, resulting in low atmospheric pressure and induces a weak inflow of air at the surface. Air which rises in a heat low is very dry so clouds seldom form. Rising air above a heat low produces a warm upper level high and results in a net outflow of air aloft. Heat lows remain practically stationary over areas which produce them. 
Heat of Combustion
  • The heat energy resulting from the complete combustion of a fuel, expressed as the quantity of heat per unit weight of fuel. The high heat of combustion is the potential available, and the low heat of combustion is the high heat of combustion minus several losses that occur in an open system (primarily heat of vaporization of moisture in the fuel) . 
Heat per Unit Area
  • Total amount of heat released per unit area as the flaming front of the fire passes, expressed as Btu/square foot; a measure of the total amount of heat released in flames. 
Heat Probe
  • Apparatus used to detect heat. 
Heat Release Rate
  1. Total amount of heat produced per unit mass of fuel consumed per unit time.
  2. Amount of heat released to the atmosphere from the convective-lift fire phase of a fire per unit time. 
Heat Transfer
  • Process by which heat is imparted from one body to another, through conduction, convection, and radiation. 
Heat Trough
  • A Heat Low which is elongated in shape. Also called: Heat Low; Thermal Low; Thermal Trough. 
Heat Value
  • The total heat energy released during combustion, usually published as units of heat energy produced per unit mass of ovendry fuel consumed. 
Heat Yield
  • The heat of combustion corrected for various heat losses, mainly the presence of moisture in the fuel. To a very close approximation, the quantity of heat per pound of fuel burned that passes through a cross section of the convection column above a fire that is burning in a neutrally stable atmosphere. Also called low heat of combustion. 
Heavy Equipment Transport
  • Any ground vehicle capable of transporting a dozer, tractor, or other heavy piece of equipment. Also called lowboy. 
Heavy Fuels
  • Fuels of large diameter such as snags, logs, large limbwood, which ignite and are consumed more slowly than flash fuels. Also called coarse fuels. 
Heel of the Fire
  • The vertical measurement of vegetation from the top of the crown to ground level. 
Held Line
  • All control line that still contains the fire when mopup is completed. Excludes lost line, natural barriers not backfired, and unused secondary lines. 
  • The main location within the general incident area for parking, fueling, maintenance, and loading of helicopters. It is usually located at or near the incident base. 
Helibase Crew
  • A crew of individuals who may be assigned to support helicopter operations. 
  • Specially designed bucket carried by a helicopter like a sling load and used for aerial delivery of water or fire retardants. 
Helicopter Tender
  • A ground service vehicle capable of supplying fuel and support equipment to helicopters. 
  • A permanent facility for the operation of helicopters which has been built to FAA standards and which is marked on aeronautical charts. Natural resource agencies refer to agency heliports as permanent helibases. 
  • Lightweight portable pump developed for transport by helicopter. 
  • A natural or improved takeoff and landing area intended for temporary or occasional helicopter use. 
  • The utilization of helicopters to transport crews, equipment, and fire retardants or suppressants to the fireline during the initial stages of a fire. The term also refers to the crew that performs helicopter management and attack activities. 
Helitack Crew
  • A crew of firefighters specially trained and certified in the tactical and logistical use of helicopters for fire suppression. 
  • Specially designed tank, generally of fabric or metal, fitted closely to the bottom of a helicopter and used for transporting and dropping suppressants or fire retardants. 
  • A helicopter equipped with a fixed tank, Airtanker Board certified, capable of delivering a minimum of 1,100 gallons of water, foam, or retardant. 
  • A plant that does not develop woody, persistent tissue but is relatively soft or succulent and sprouts from the base (perennials) or develops from seed (annuals) each year. Includes grasses, forbs and ferns. 
Herbaceous Fuel Moisture
  • In NFDRS, a calculated value representing the approximate moisture content of the live herbaceous vegetation in the rating area expressed as a percentage of the oven dry weight of the sample. 
Herbaceous Stage
  • The modeled condition of herbaceous vegetation (pre-green, green-up, transition, cured, frozen) for the 1978 version of NFDRS. 
Hidden Fire Scar
  • Fire scar in a tree resulting from fire injury to the cambium without destruction of the overlying bark and therefore not readily discernible. 
Higbee Cut
  • Removal of the first (i.e., outside) thread of a female or male coupling to prevent crossing or mutilation of threads. Dimpled rocker lug on female coupling indicates beginning of Higbee Cut. 
High Expansion
  • Foam with an expansion between 201:1 and 1000:1. 
High Fire Risk Day
High Pressure Fog
  • Small capacity spray jet produced at very high pressures (greater than 250 psi, the normal maximum pressure for standard ground tankers) and discharged through a small hose with a gun-type nozzle. 
Historical Weather Station
  • In WIMS, a weather station that is no longer in service for which access to archived observations is still available in NIFMID. 
Holding Actions
  • All actions taken to stop the spread of fire. 
Holding Orbit
  • A predetermined maneuver which keeps an aircraft within a specified airspace while awaiting further orders. 
Holding Resources
  • Resources assigned to do all required fire suppression work following fireline construction but generally not including extensive mopup.  Also known as Holding Forces.
Holdover Fire
  • A fire that remains dormant for a considerable time. Also called sleeper fire. 
  • An adjective that describes a permanent place associated with a resource.
Home Assessment
  • Evaluation of a dwelling and its immediate surrounding to determine its potential to escape damage by an approaching wildland fire. Includes the fuels and vegetation in the yard and adjacent to the structure, roof environment, decking and siding materials, prevailing winds, topography, fire history, etc., with the intent of mitigating fire hazards and risks. 
Home Ignition Zone (HIZ)
  • The area where the factors that principally determine home ignition potential during extreme wildfire behavior (high fire intensities and burning embers) are present. The characteristics of a home and its immediate surroundings within 100 feet comprise the HIZ.
Home Location
  • The physical location of a resource when not on assignment.
Home Unit
  • The designated agency or entity providing contracted resources that employs the individual who is actively pursuing a position performance assignment (completion of a position task book). 
Horizontal Fuels Arrangement
  • Composition of fuel laterally across the landscape.
Hose Clamp
  • Crimping device for stopping the flow of water in a hose. 
Hose Lay
  • Arrangement of connected lengths of fire hose and accessories on the ground, beginning at the first pumping unit and ending at the point of water delivery. 
Hose Line Tee
  • A fitting that may be installed between lengths of hose to provide an independently controlled outlet for a branch line. 
Hose Rack
  • Item for storing drying fire hose. 
Hose Reel
  • A rotating drum used for winding booster hose (normally) for storing and dispensing. 
Hose Thread
  • The specific dimensions of screw thread employed to coupled fire hose and equipment. American National Standards (NH) have been adopted for fire hose couplings threads in 3/4, 1-1/2, 2-1/2, 3-1/2, 4, 5, and 6-inch sizes. 
Hose Washer
  • Device for cleaning the exterior of fire hose. 
  • A term historically used to indicate the agency or unit with jurisdiction or protection responsibilities or who was financially responsible for the incident response. Its use is not recommended.
Hotshot Crew
  • Intensively trained fire crew used primarily in handline construction (Type-1). 
  • A particularly active part of a fire. 
  • Checking the spread of fire at points of more rapid spread or special threat. Is usually the initial step in prompt control, with emphasis on first priorities. 
  • A stationary in-flight condition for helicopters when no directional flight is achieved. 
Hover Ceiling
  • Highest altitude above sea level at which a helicopter can hover at maximum computed gross weight. It is generally specified whether the quoted hover ceiling refers to hovering in ground effect (HIGE) or hovering out of ground effect (HOGE). 
Hover Hook-up
  • Attaching of a cargo lead line to a hovering helicopter. 
  • The process by which a helicopter fills a helibucket while hovering above the water source. 
Hovering in Ground Effect (HIGE)
  • The situation in which a helicopter is hovering sufficiently close to the ground to achieve added lift due to the effects of "ground cushion." The HIGE ceiling, for a given gross weight, thus is greater than the HOGE (Hovering Out of Ground Effect) ceiling.
Human-caused Fire
  • Any fire caused directly or indirectly by person(s). 
Human-caused Risk
  • Part of the National Fire Danger Rating System (NFDRS). A model for predicting the average number of reportable human caused fires from a given ignition component value. 
Human-caused Risk Scaling Factor
  • Part of the National Fire Danger Rating System (NFDRS). Number relating human-caused fire incidence to the ignition component in a fire danger rating area. It is based on three to five years of fire occurrence and fire weather data that adjusts the prediction of the basic human-caused fire occurrence model to fit local experience. 
  • Layer of decomposed organic matter on the forest floor beneath the fermentation layer and directly above the soil. It is that part of the duff in which decomposition has rendered vegetation unrecognizable and mixing of soil and organic matter is underway. 
  • Resistance to wetting exhibited by some soils, also called water repellency. The phenomenon may occur naturally or may be fire-induced. It may be determined by water drop penetration time, equilibrium liquid-contact angles, solid-air surface tension indices, or the characterization of dynamic wetting angles during infiltration. 
  • Recording instrument combining, on one paper record, the variation of dry-bulb temperature and relative humidity as a function of time. 
  • An area that, in relation to wildland/urban fire, has a set of conditions that provides the opportunity for fire to burn from wildland vegetation to the home/structure ignition zone. 
Identification Run
  • Dry run over the target area by the leadplane to indicate an airtanker's flight path and target, while the airtanker pilot is observing. 
  • A pyrotechnic device specifically designed to initiate burning of a fuel mixture or propellant. 
Ignition Area (IA)
  • The smallest area that a wildland fire investigator can define based on the physical evidence of the fire pattern indicators, within the specific origin area, in which a competent ignition source came into contact with the first fuel ignited and combustion was sustained. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
Ignition Component
  • Part of the National Fire Danger Rating System (NFDRS). A rating of the probability that a firebrand will cause an actionable fire. 
Ignition Energy
  • Quantity of heat or electrical energy that must be absorbed by a substance to ignite and burn. 
Ignition Factor
Ignition Method
  • The means by which a fire is ignited, such as hand-held drip torch, helitorch, and backpack propane tanks. 
Ignition Pattern
  • Manner in which a prescribed fire is ignited. The distance between ignition lines or points and the sequence of igniting them is determined by weather, fuel, topography, firing technique, and other factors which influence fire behavior and fire effects. 
Ignition Probability
  • Chance that a firebrand will cause an ignition when it lands on receptive fuels. (Syn. IGNITION INDEX) 
Ignition Sequence
Ignition Source
Ignition Time
  • Time between application of an ignition source and self-sustained combustion of a fuel. 
Ignition Trigger
  • A causative agent for wildland fire. For example, human or lightning. 
IMI Interactivity Levels
IMI Level 1 Interactivity
  • This is the lowest level of courseware development. It is normally a knowledge familiarity lesson, provided in a linear format (one idea after another). Use Level 1 to introduce an idea or concept, or to familiarize. Provide minimal interactivity by using selectable screen icons that are inserted into the linear, or almost linear, flow of the courseware. Allow the student little or no control of the sequence of instructional media presented, including: simple developed graphics, clip art, customer provided video and audio segments (clips). Make use of typical input/output peripherals throughout the lesson. 
IMI Level 2 Interactivity
  • This involves the recall of more information than a level 1 and allows the student more control over the lesson scenario through screen icons and other peripherals, such as light pens or touch screens. Typically level 2 is used for non-complex operations and maintenance lessons. Simple emulations or simulations are presented to the user. As an example, the user is requested to rotate switches, turn dials, make adjustments, or identify and replace a faulted component as part of a procedure. This also may include simple to standard developed graphics, and/or clip art, and video and audio clips. 
IMI Level 3 Interactivity
  • This involves the recall of more complex information (compared to levels 1 and 2) and allows the user an increased level of control over the lesson scenario through peripherals such as light pen, touch screen, track ball, or mouse. Video, graphics, or a combination of both is presented simulating the operation of a system, subsystem, or equipment to the user. The lesson scenario training material typically is complex and involves more frequent use of peripherals to affect a transfer of learning. Operation and maintenance procedures are normally practiced with level 3 scenarios and students may be required to alternate between multiple screens to keep pace with the lesson material. Multiple software branches (two to three levels) and rapid response are provided to support remediation. Emulations and simulations are an integral part of this presentation. This may also include complex developed graphics, and/or clip art, and video and audio clips. 
  • Rotating part of a centrifugal pump which imparts energy to the liquid to be moved. For shearing purposes, the impeller is on a rotating shaft within the body of liquid. 
Implementation Plan
  • The design and definition of all the activities, resources, limitations, and contingencies required for successful wildland fire management. 
  • A term used in weather primarily to describe a weak disturbance that does not necessarily have an associated storm center or surface low. The disturbance usually does not create severe weather and is frequently associated with a marine air push. 
In-stand Wind
  • Wind speed within a stand at about eye level. 
  • A burning compound or metal used to produce intense heat or flame, like a bomb. 
Incendiary Device
  • Contrivance designed and used to start a fire. 
Incendiary Fire
  • A fire that is intentionally ignited in an area or under circumstances where and when there should not be a fire.  Source:  NFPA 921 (2017) 3.3.116
  • An occurrence either human-caused or natural phenomenon, that requires action or support by emergency service personnel to prevent or minimize loss of life or damage to property and/or natural resources. 
Incident Action Plan (IAP)
  • Contains objectives reflecting the overall incident strategy and specific tactical actions and supporting information for the next operational period. The plan may be oral or written. When written, the plan may have a number of attachments, including: incident objectives, organization assignment list, division assignment, incident radio communication plan, medical plan, traffic plan, safety plan, and incident map. Formerly called shift plan. 
Incident Agency
  • The organizational unit responsible for the incident activities.
Incident Assignment
  • An assignment to an incident that requires a length of commitment.
Incident Base
  • Location at the incident where the primary logistics functions are coordinated and administered. (Incident name or other designator will be added to the term Base.) The incident command post may be collocated with the base. There is only one Base per incident. 
Incident Blanket Purchase Agreement (IBPA)
  • A pre-season agreement for equipment, supplies, or services to be used on fire and all-hazards incidents, issued on a Solicitation/Contract/Order for Commercial Items, SF-1449 form. I-BPAs are awarded on a competitive basis using commercial item procedures.
Incident Command Post (ICP)
  • Location at which primary command functions are executed. The ICP may be collocated with the incident base or other incident facilities. 
Incident Command System (ICS)
  • A standardized on-scene emergency management concept specifically designed to allow its user(s) to adopt an integrated organizational structure equal to the complexity and demands of single or multiple incidents, without being hindered by jurisdictional boundaries. 
Incident Communications Center
  • The location of the communications unit and the message center. 
Incident Complex
  • Business Rules
    • An Incident complex is not a wildfire incident and is not interchangeable with a wildfire record.
    • An Incident Commander or Incident Management Team may manage multiple wildfires without creating an incident complex.
  • Source: Event Kind Category Revision Rational Document
Incident Management Team
  • The incident commander and appropriate general and command staff personnel assigned to an incident. 
Incident Medical Specialist Program
  • An incident-based program to care for emergent and minor medical as well as common occupational health care problems of incident personnel. This program may be deployed to Type I and Type II incidents. Currently, this program is only available in three regions: Northwest (R6), Northern Rockies (R1) and Alaska (R10). In Alaska, the program is known as the Firemedic. 
Incident Objectives
  • Incident-specific statements of direction necessary for the selection of strategy(s) and tactical activities of resources on an incident.
    • Definition Extension:  1)  Incident objectives are derived from the management goals of the Authority Having Jurisdiction (AHJ).  2)  Incident Objectives should be attainable and measurable, yet flexible enough to allow for strategic and tactical alternatives.
Incident Order Number
  • The number assigned to an incident. This number follows a standard format where the first two letters indicate the state, the next letters are the incident agency, and the last six digits are agency assigned.
Incident Organization
  • Resources, together with a complement of overhead personnel, calculated to be sufficient to provide fire efficient incident management. 
Incident Overhead
  • All supervisory positions described in the Incident Command System. 
Incident Qualifications Card
  • A card issued to persons showing their incident management and trainee qualifications to fill specified fire management positions in an incident management organization. 
Incident Support Cache
  • Refers to type 1 (national interagency support cache), type 2 (national interagency support cache satellite), and type 3 (local interagency support cache). Caches may consist of a pre-determined complement of tools, equipment and/or supplies stored in a designated location, available for incident use.
Incident Support Organization
  • Includes any off-incident support provided to an incident. Examples would be agency dispatch centers, airports, mobilization centers, etc. 
Incident Weather Forecast
Incident with Potential
  • Wildland fire-related mishap that results in serious or non-serious injuries involving multiple personnel, near accident (which would have resulted in a serious injury or fatality), or substantial loss of property (less than $250,000). The mishap may be so complex and fraught with operational discrepancies that it has the potential to produce an accident, serious injury, or fatality given a similar environment or set of circumstances that existed at the time of the incident. 
  • Increasing coupling used on hose, pump, or nozzles to permit connection of a larger size of hose. 
Incremental Drop
  • Airtanker drop in which tank doors are opened in sequence so that fire retardant cascades somewhat continuously. 
Independent Action
  • Fire suppression activities by other than regular fire suppression organizations or a fire cooperator. 
Independent Crown Fire
  • A fire that advances in the tree crowns alone, not requiring any energy from the surface fire to sustain combustion or movement. Also called running crown fire. 
Indicated Airspeed (IAS)
  • The speed of an aircraft as shown on its pitot static airspeed indicator. Calibrated to reflect standard atmosphere adiabatic compressible flow at sea level, uncorrected for airspeed system errors. 
  • Visual remains at a fire scene revealing the fire?s progress and action. 
Indicator Categories
  • Classification of indicators into a variety of categories based on how they are formed and the types of material they are found on. 
Indirect Attack
  • A method of suppression in which the control line is located some considerable distance away from the fire's active edge. Generally done in the case of a fast-spreading or high-intensity fire and to utilize natural or constructed firebreaks or fuel breaks and favorable breaks in the topography. The intervening fuel is usually backfired; but occasionally the main fire is allowed to burn to the line, depending on conditions. 
  • A control mechanism that allows a regulated quantity of foam concentrate to be introduced into the main hose line. 
Industrial Fire Precaution Level (IFPL)
  • An application of fire danger rating to support regulation of contractors involved in land management activities for fire prevention purposes in the Pacific Northwest. 
Infrared (IR)
  • A heat detection system used for fire detection, mapping, and hotspot identification.
Infrared Groundlink (IR)
  • A capability through the use of a special mobile ground station to receive air-to-ground IR imagery at an incident. 
  • Process of extinguishing fire by the use of an agent that interrupts the chemical reactions in the combustion process. 
  • Any agent which retards a chemical reaction. 
Initial Action
Initial Attack (IA)
Initial Attack Crew
  • Specially trained and equipped fire crew for initial attack on a fire. 
Initial Attack Fire (IAF)
  • Fire that is generally contained by the attack units first dispatched, without a significant augmentation of reinforcements, within two hours after initial attack, and full control is expected within the first burning period. 
Initial Investigative Area
Initial Response
Inmate Crew
  • Any fire crew composed of prison inmates or wards. 
Inside Diameter (ID)
  • The internal diameter of a tube, conductor, or coupling, as distinguished from its OD (Outside Diameter). Fire hose sizes are classified by a nominal internal diameter. 
Instrument Flight Rules Conditions (IFR)
  • Weather conditions below the minimum for flight under Visual Flight Rules and therefore requiring the observance of instruments inside the aircraft for controlling flight; generally considered to be less than 1000' AGL and 3 miles distant. 
Instrument Landing System (ILS)
  • System for airplane landing in which the pilot is guided by radio beams. 
Instrument Shelter
  • Naturally or artificially ventilated structure, constructed to specifications and used to shield weather measuring instruments from direct sunshine and precipitation. 
Interactive Multimedia Instruction (IMI)
  • A group of predominantly interactive, electronically delivered training. IMI products include instructional software and software management tools used in support of instructional programs. IMI products are teaching and management tools and may be used in combination or individually. Used individually, not all IMI products can be considered interactive, multimedia, or instructional. However, IMI products, when used in combination with one another, are interactive, multimedia, and instructional. IMI technology is one of the primary technologies to be used in distance learning. 
Interagency Authoritative Data Source (IADS)
  • A product, tool, or IT application that has been designated as the trusted source for wildland fire data. This source may also create and update transactional data for use in other applications. There may be more than one IADS and it can change depending on business process complexity and life cycle. An IADS may be a compilation or subset of data from other authoritative sources. The DLM process ensures sources, limitations, currency, and attributes for the IADS are documented.
Interagency System of Record (ISOR)
  • Agencies and bureaus may have their own SOR for their data. An ISORs are identified by an interagency business area as the official application source of interagency data. An ISOR is the source that resolves duplicate records that may arise from various IADSs and ensures the data meets defined quality standards before it is included in official historical data sets. An ISOR can be an external source of data used by wildland fire.
Intermittent Smoke
  • Smoke which becomes visible only at intervals. 
Internal Load
  • Load carried inside the fuselage structure of an aircraft. 
Internal Payload
  • Allowable aircraft cabin load, in pounds, with full fuel and pilot in calm air at standard atmosphere. 
  • Atmospheric inversion. The departure from the usual increase or decrease with altitude of the value of an atmospheric property. In fire management usage, nearly always refers to an increase in temperature with increasing height. Also, the layer through which this departure occurs (also called inversion layer.) The lowest altitude at which the departure is found is called the base of the inversion. 
Iron Pipe Thread (IPT)
  • A tapered thread standard that is used for connecting various sizes of rigid pipe. This standard may be referred to as tapered iron pipe thread (TIPT), National pipe thread (NPT), iron pipe thread (IPT), or iron pipe standard thread (IPS). With tapered thread, the threads and pipe sealant perform the seal at the connection. This is opposed to straight thread connectors which use a gasket to form the seal. 
  • An unburned area within a fire perimeter. 
  • A line connecting points of equal atmospheric pressure on a weather map. 
  • A line connecting points of equal temperature on a weather map. 
Isothermal Layer
  • Layer through which temperature remains constant with elevation. 
Jackpot Burn
  • A fire treatment type. A prescribed fire to deliberately burn natural or modified concentrations (jackpots) of wildland fuels under specified environmental conditions, which allows the fire to be confined to a predetermined area and produces the fireline intensity and rate of spread required to attain planned resource Management Objectives.
  • Disposing of cargo, fuel, water or retardant overboard to lighten an aircraft or to improve its stability. 
Job Aid
  • Detailed information needed to complete each task including step-by-step explanations, checklists, diagrams and other relevant information. Job aids are for use by trainees as an on-the-job training tool and as a field operational tool for qualified personnel.
Job Hazard Analysis
  • A job hazard analysis identifies hazards associated with work projects and worksites, and identifies protective equipment or modified work procedures needed. 
Joint Information Center (JIC)
  • A facility established as the central point of contact for news media and interest parties to coordinate incident information activities at the scene of the incident. Public information officials from all participating federal, state, and local agencies should collocate at the JIC. 
Joint Information System (JIS)
  • A system that integrates incident information and public affairs into a cohesive organization designed to provide consistent, coordinated, timely information during crisis or incident operations. 
Jump Spot
  • Selected landing area for smokejumpers. 
Jump Suit
  • Approved protection suit worn for smokejumping. 
  • The range or sphere of authority. Public agencies have jurisdiction at an incident related to their legal responsibilities and authority for incident mitigation. Jurisdictional authority at an incident can be political/geographical (e.g., city, county, state or federal boundary lines), or functional (e.g., police department, health department, etc.). 
Jurisdictional Agency
  • The agency having land and resource management responsibility for a specific geographical or functional area as provided by federal, state or local law. 
Keetch-Byram Drought Index (KBDI)
  • An estimate (0-800) of the amount of precipitation (in 100ths of inches) needed to bring the top 8 inches of soil back to saturation. A value of 0 is complete saturation of the soil, a value of 800 means 8.00 inches of precipitation would be needed for saturation. In the 1988 version of NFDRS, outputs of KBDI are used to adjust live and dead fuel loadings. 
Kindling Point
  • Lowest temperature at which sustained combustion can be initiated for a specified substance. Also called ignition temperature. 
Knock Down
  • To reduce the flame or heat on the more vigorously burning parts of a fire edge. 
  • Nautical miles per hour, equal to 1.15 mph. 
Ladder Fuels
  • Fuels which provide vertical continuity between strata, thereby allowing fire to carry from surface fuels into the crowns of trees or shrubs with relative ease. They help initiate and assure the continuation of crowning. 
Land Occupancy Fire
  • Fire started as a result of land occupancy for agricultural purposes, industrial establishment, construction, maintenance and use of rights-of-way, and residences, except equipment use and smoking. 
Land Use Plan
  • A set of decisions that establish management direction for land within an administrative area; an assimilation of land-use-plan-level decisions developed through the planning process regardless of the scale at which the decisions were developed. 
Land/Resource Management Plan (L/RMP)
  • The person or entity that owns the land or has the authority to convey title to others.
    • Definition Extension: Landowner or Owner are not directly interchangeable with Jurisdictional Unit or Protecting Unit. For example, acres burned may be reported for “private” landownership but “private” would not be identified as a Jurisdictional Unit.
Lapse Rate
  • Change of an atmospheric variable (temperature unless specified otherwise) with height. 
Large Aircraft
  • Aircraft in which maximum certified gross weight at take-off exceeds 12,500 pounds. 
Large Fire
  1. For statistical purposes, a fire burning more than a specified area of land e.g., 300 acres.
  2. A fire burning with a size and intensity such that its behavior is determined by interaction between its own convection column and weather conditions above the surface. 
Large Fire-Day
  • In FireFamily Plus, a day with both a weather observation and at least one large (as defined by the user) fire. 
Lateral Fire
Lead Line
  • Line or set of lines made of rope, webbing, or cable and used in helicopter external load operations; usually placed between a swivel or the cargo hook and the load. 
  • The ICS title for an individual responsible for a task force, strike team, or functional unit. 
Leaders Intent
  • A concise statement that outlines what individuals must know in order to be successful for a given assignment. The intent communicates three essential pieces of information:
    • Task - What is the goal or objective
    • Purpose - Why it is to be done
    • End state - How it should look when successfully completed 
  • The art of providing purpose, direction, and motivation to a group of people in order to accomplish a mission and improve the organization. Leaders provide purpose by clearly communicating their intent and describing the desired end state of an assignment to their followers. Leaders provide direction by maintaining standards of performance for their followers. Leaders provide motivation by setting the example for their followers. 
  • Aircraft with pilot used to make trial runs over the target area to check wind, smoke conditions, topography and to lead airtankers to targets and supervise their drops. 
Leapfrog Method
  • A system of organizing workers in fire suppression in which each crew member is assigned a specific task such as clearing or digging fireline on a specific section of control line, and when that task is completed, passes other workers in moving to a new assignment. 
Learning Content Management System (LCMS)
  • Any system that keeps learner information, can launch and communicate with SCOs, and can interpret instructions that tell it which SCO comes next. 
Learning Objective
  • A description of the intended outcome of a training class, program, or evolution. The learning objective identifies the condition, the task, and the standard to which the student much achieve. 
Learning Objects
  • Reusable learning objects represent an alternative approach to content development. In this approach, content is broken down into chunks. From a pedagogical perspective, each chunk might play a specific role within an instructional design methodology. Such chunks are called learning objects. There is no standard for the size (or granularity) of a learning object. Larger learning objects are typically harder to reuse, and smaller learner objects save less work for those who reuse them. Normally the happy medium has been estimated as between five and fifteen minutes of learning material. The requirements for each chunk are:
    • Each chunk must be able to communicate with learning systems using a standardized method that does not depend on the system.
    • What happens within a chunk is the chunk's business.
    • How a learner moves between chunks is controlled by the learning system.
    • Each chunk must have a description (metadata tag) that enables designers to search for and find the right chunk for the right job. 
Legitimate Smoke
  • Smoke from any authorized use of fire (e.g., locomotive, industrial operations, permitted debris burning). 
Level of Certainty
Level of Service
  • Amount of fire prevention and fire suppression supplied; may be expressed several ways (e.g., percent of people or buildings protected, area protected, dollar value of property protected, firefighters per capita, water flow capability). 
  • Refers to the joint consideration of both the life and physical well-being of individuals. 
Lifting Processes
  • Any of the processes that lead to upward vertical motion in the atmosphere. These processes may include low level convergence, heating or thermal convection, orographic lifting over the mountains, and frontal lifting. 
Light (Fine) Fuels
  • Fast-drying fuels, generally with a comparatively high surface area-to-volume ratio, which are less than 1/4-inch in diameter and have a timelag of 1 hour or less. These fuels readily ignite and are rapidly consumed by fire when dry. 
Light Wind
  • Wind speed less than 7 mph (6 knots) measured at 20 feet above ground. At eye level, light winds are less than 3 mph (3 knots). 
Lightning Activity Level (LAL)
  • Part of the National Fire Danger Rating System (NFDRS). A number, on a scale of 1 to 6, which reflects frequency and character of cloud-to-ground lightning (forecasted or observed). The scale for 1 to 5 is exponential, based on powers of 2 (i.e., LAL 3 indicates twice the lightning of LAL 2). LAL 6 is a special category for dry lightning and is closely equivalent to LAL 3 in strike frequency. 
Lightning Fire
  • Wildfire caused directly or indirectly by lightning. 
Lightning Fire Occurrence Index
  • Part of the National Fire Danger Rating System (NFDRS). Numerical rating of the potential occurrence of lightning-caused fires. 
Lightning Risk (LR)
  • Part of the National Fire Danger Rating System (NFDRS). A number related to the expected number of cloud-to-ground lightning strokes to which a protection unit is expected to be exposed during the rating period. The LR value used in the occurrence index includes an adjustment for lightning activity experienced during the previous day to account for possible holdover fires. 
Lightning Risk Scaling Factor
  • Part of the National Fire Danger Rating System (NFDRS). Factor derived from local thunderstorm and lightning-caused fire records that adjusts predictions of the basic lightning fire occurrence model to local experience, accounting for factors not addressed directly by the model (e.g., susceptibility of local fuels to ignition by lightning, fuel continuity, topography, regional characteristics of thunderstorms). 
Lightning Stroke Counter
  • Electronic sensor used to record the number of lightning strokes within a predetermined range over a specified period of time. 
Lightweight Debris
  • Removing branches from a felled or standing tree, or from brush. 
Limited Containment
  • Halting of fire spread at the head, or that portion of the flanks of a prescribed fire that is threatening to exceed prescription criteria, and ensuring that this spread rate will not be encountered again; does not indicate mopup. 
Line Cutter
  • Fire crew member in the progressive method of line construction who cuts and clears away brush, small saplings, vines, and other obstructions in the path of the fireline; usually equipped with ax or brush hook, or pulaski. 
Line Officer
  • Managing officer, or designee, of the agency, division thereof, or jurisdiction having statutory responsibility for incident mitigation and management. 
Line Scout
  • A firefighter who determines the location of a fire line. 
Lined Fire Hose
  • Fire hose with a smooth inner coating of rubber or plastic to reduce friction loss. 
Liquid Concentrate (LC)
  • Liquid phosphate fertilizers used as fire retardants, usually diluted three to five times prior to application. 
  • The top layer of forest floor, composed of loose debris of dead sticks, branches, twigs, and recently fallen leaves or needles; little altered in structure by decomposition. 
Little Change
  • Insignificant change in wind speed, direction, and temperature (less than 5 degrees) and relative humidity (less than five percent), respectively. When used as a general statement in a long-range forecast, all four criteria apply. 
Live Fuel Moisture Content
  • Ratio of the amount of water to the amount of dry plant material in living plants. 
Live Fuels
  • Living plants, such as trees, grasses, and shrubs, in which the seasonal moisture content cycle is controlled largely by internal physiological mechanisms, rather than by external weather influences. 
Live Herbaceous Moisture Content
  • Ratio of the amount of water to the amount of dry plant material in herbaceous plants (i.e., grasses and forbs). 
Live Line
  • Hose line filled with water under pressure and ready to use. 
Live Reel
  • Hose line or reel on a fire engine, carried preconnected to the pump, ready for use without making connections to pump or attaching nozzle. 
Live Run
  • Indicates that the airtanker has the target in sight and will make a retardant drop on this run over the target. 
Live Woody Moisture Content
  • Ratio of the amount of water to the amount of dry plant material in shrubs. 
Load and Hold
  • An order given to the airtanker pilot to pick up another load of retardant or water and hold at the reload base. The tanker is still committed to the fire. 
Load and Return
  • Order given to the airtanker pilot to pick up another load of fire retardant or water and return to the fire. 
Load Calculation Form
  • An agency form used to calculate helicopter allowable payload. 
Loading Pad
  • Concrete pad at a retardant base on which aircraft stand when being loaded. 
  • Individual responsible to the Deck Coordinator for the manifesting, loading and unloading of personnel, equipment and cargo. 
Local Agency
  • Any agency having jurisdictional responsibility for all or part of an incident. 
Local Resource
  • Resources within a dispatch center's area of responsibility. 
Local Responsibility Area
  • Lands on which neither the state nor the federal government has any legal responsibility for providing fire protection. 
Local Winds
Logging Debris
  • Unwanted tree parts (crowns, logs, uprooted stumps) remaining after harvest. 
Logistics Section
  • The ICS section responsible for providing facilities, services, and supplies in support of an incident. 
Long-Range Forecast
Long-Range Spotting
  • Large glowing firebrands are carried high into the convection column and then fall out downwind beyond the main fire starting new fires. Such spotting can easily occur 1/4 mile or more from the firebrand's source. 
Long-Term Fire Danger
  • The results of those factors in fire danger affecting long-term planning; involves consideration of past records and conditions and probable future trends. 
Long-term Fire Residence
Long-Term Fire Retardant
  • Chemical that inhibits combustion primarily through chemical reactions between products of combustion and the applied chemicals, even after the water component has evaporated. Other chemical effects also may be achieved, such as film-forming and intumescence. 
  • A line or set of lines, usually in 50' increments, used in external load operations that allow the helicopter to place loads in areas in which the helicopter could not safely land. 
  1. A person designated to detect and report fires from a vantage point.
  2. A location from which fires can be detected and reported.
  3. A fire crew member assigned to observe the fire and warn the crew when there is danger of becoming trapped. 
Lookout Tower
  • Structure that elevates a person above nearby obstructions to sight for fires; generally capped by some sort of house or cupola. 
Lookout(s), Communication(s), Escape Route(s), and Safety Zone(s) (LCES) 
  • Elements of a safety system used by fire fighters to routinely assess their current situation with respect to wildland firefighting hazards. 
  • After felling, cutting branches, tops, and unwanted boles into lengths such that resultant logging debris will lie close to the ground. 
Lopping and Scattering
  • Lopping logging debris and spreading it more or less evenly over the ground. 
Lost Line
  • Any part of a fireline rendered useless by a breakover of the fire. 
  • An area of relatively low atmospheric pressure in which winds tend to move in a counterclockwise direction, spiraling in toward the low's center.  Source: http://glossary.ametsoc.org/wiki/Low
Low Expansion
  • Foam with an expansion between 1:1 and 20:1. 
Macroscale Fire Pattern Indicator
  • Large single fire pattern indicator or overall patterns of indicators that are readily visible from a distance. 
Main Ridge
  • Prominent ridgeline separating river or creek drainages. Usually has numerous smaller ridges (spur) extending outward from both sides. 
Major Disaster
  • Any natural catastrophe or, regardless of cause, any fire, flood, or explosion, in any part of the United States, which in the determination of the President causes damage of sufficient severity and magnitude to warrant major disaster assistance. 
Major Repair (Aviation)
  • A repair (1) that, if improperly done, might appreciably affect weight, balance, structural strength, or other qualities affecting airworthiness or (2) that is not done according to accepted practices or cannot be done by elementary operations. 
Male Coupling
  • An externally threaded hose nipple which fits in the thread of a female (internally threaded) swivel coupling of the same pitch and diameter. Nozzles attach to this type of coupling. 
Management Action Points
  • Geographic points on the ground or specific points in time where an escalation or alternative of management actions is warranted. These points are defined and the management actions to be taken are clearly described in an approved Prescribed Fire Plan. Timely implementation of the actions when the fire reaches the action point is generally critical to successful accomplishment of the objectives. Also called Trigger Points. 
Management by Objectives
  • In ICS, this is a top-down management activity which involves a three-step process to achieve the incident goal. The steps are: establishing the incident objectives, selection of appropriate strategy(s) to achieve the objectives; and the tactical direction associated with the selected strategy. Tactical direction includes: selection of tactics, selection of resources, resource assignments and performance monitoring. 
Management Requirements
  • The technical and scientific specifications for management activities or potential actions mandated by the agency administrator and defined in land/resource management plans. Management requirements are derived from land/resource management plan and fire management plan standards and guidelines information. 
  • Individuals within ICS organizational units that are assigned specific managerial responsibilities, e.g., staging area manager or camp manager. 
Manual Weather Station
  • A non-telemetered weather station that provides one observation every 24 hours for manual entry into WIMS. 
Manually Regulated
  • A proportioning method or device that requires a manual adjustment to maintain a desired mix ratio over a changing range of water flows and pressures. 
Marine Air
  • Air which has a high moisture content and the temperature characteristics of an ocean surface due to extensive exposure to that surface. An intrusion of marine air will moderate fire conditions. Absence of marine air in coastal areas may lead to more severe fire danger. 
Marine Climate
Maritime Air
Mass Arsonist
  • An offender who sets three or more fires at the same location during a limited period of time. 
Mass Fire
  • A fire resulting from many simultaneous ignitions that generates a high level of energy output. 
Master Fire Chronology
  • Chronological listing of the dates of fires documented in a designated area, the dates being corrected by crossdating. Size of the area must be specified. Also called composite fire interval. 
Material First Ignited
Mathematical Model
  • A model that is a quantitative and mathematical representation or simulation which attempts to describe the characteristics or relationship of physical events. 
  • Hand tool with a narrow hoeing surface at one end of the blade and a pick or cutting blade at the other end; used for digging and grubbing. 
Maximum Certified Gross Weight
  • Absolute maximum allowable gross weight for an aircraft as established by the manufacturer and approved by the FAA. 
Maximum Computed Gross Weight
  • Computed gross weight for an aircraft, obtained from the appropriate performance chart, which is the maximum gross weight appropriate to the applicable circumstance of configuration and/or environmental conditions. 
Maximum Dry Bulb Temperature
  • The highest value for dry bulb temperature measured at the observation site during the preceding 24-hour period. 
Maximum Manageable Area (MMA)
  • The maximum geographic limits of spread within which a wildland fire is allowed to spread. 
Maximum Relative Humidity
  • The highest value for relative humidity measured at the observation site during the preceding 24-hour period. 
May Day
  • International distress signal/call. When repeated three times it indicates imminent and grave danger and that immediate assistance is required. 
  • A combination hoe or cutting tool and rake, with or without removable blades. 
Mean Fire Return Interval
  • Arithmetic average of all fire intervals in a given area over a given time. 
Mean Sea Level (MSL)
  • Average height of the surface of the sea for all stages of the tide over a 19-year period. NOTE: when the abbreviation MSL is used in conjunction with a number of feet, it implies altitude above sea level (e.g., 1000 feet MSL).  Source:  http://glossary.ametsoc.org/wiki/Mean_sea_level
Measured Woody Fuel Moisture
  • Moisture content of the small branch wood and foliage of live woody plants, expressed as a percentage of the oven dry weight of the sample, collected monthly and used to supplement NFDRS modeled outputs. 
Medical Unit
  • Functional unit within the logistics section that is responsible for the emergency medical and occupational health care of incident personnel. Some incident management teams have placed this unit under safety. 
Medium Expansion
  • Foam with an expansion between 21:1 and 200:1. 
Medium-range Forecast
  • Mobile medical treatment and transportation. 
Merged Wildfires
  • Two or more wildfires that burn together to form a single burned area and which, by management action, may be declared merged and managed as a single incident to improve efficiency and simplify incident management processes.

    • Definition Extension: 1) Management can decide to declare wildfires as merged or not.  2)  A merged wildfire requires a Merged Date and association with the remaining active wildfire, i.e. Merged Parent, to be identified correctly in operational and historical data.


Message Center
  • The message center is part of the incident communications center and is collocated or placed adjacent to it. It receives, records, and routes information about resources reporting to the incident, resource status, and administrative and tactical traffic. 
  • A set of standardized procedures and practices that have been peer-reviewed and have received general acceptance by the profession. 
Micro-Remote Environmental Monitoring System (Micro-REMS)
  • Mobile weather monitoring station. Each unit consists of a shipping container, solar panel, battery, temperature/relative humidity sensor, wind mast, wind direction/speed sensor, data logger and radio. A Micro-REMS usually accompanies an incident meteorologist and ATMU to an incident. 
Microscale Fire Pattern Indicator
  • Fire pattern indicators that are generally only visible when viewed within close proximity.
    • Definition Extension; This may include standing nearby, and/or the need to crouch or get down on hands and knees to observe.
Mid-Flame Windspeed
  • The speed of the wind measured at the midpoint of the flames, considered to be most representative of the speed of the wind that is affecting fire behavior. 
Military Operations Area (MOA)
  • Military Operations Area found on aeronautical charts. 
  • A unit of pressure equal to a force of 1,000 dynes per square centimeter. (A dyne is the force that would give a free mass of one gram an acceleration of one centimeter per second per second).  Source:  http://glossary.ametsoc.org/wiki/Millibar 
Mineral Ash
  • The residue of mineral matter left after complete combustion of wood (wood ash) or other organic material; consists largely of oxides, carbonates, and phosphates of Ca, K and Mg, together with other compounds. 
Mineral Soil
  • Soil layers below the predominantly organic horizons; soil with little combustible material. 
Minimum Cost Suppression Alternative
  • The alternative that achieves incident objectives, consistent with priority for firefighter and public safety, and is least expensive when considering expected costs for fire suppression and emergency stabilization and/or rehabilitation. 
Minimum Dry Bulb Temperature
  • The lowest value for dry bulb temperature measured at the observation site during the preceding 24-hour period. 
Minimum Impact Suppression Tactics
  • See Minimum Impact Suppression Techniques
Minimum Impact Suppression Techniques (MIST)
  • The application of strategy and tactics that effectively meet suppression and resource objectives with the least environmental, cultural and social impacts. 
    • Also known as Minimum Impact Suppression Tactics
Minimum Relative Humidity
  • The lowest value for relative humidity measured at the observation site during the preceding 24-hour period. 
Miscellaneous Fire
  • Fire of known cause that cannot be properly classified into any of the eight standard causes of fires. 
Mission Assignment
  • A work order issued by FEMA, with or without reimbursement, which directs another federal agency to utilize its authorities and the resources granted to it under federal law in support of state, local, tribal, and territorial government assistance.
  • Modifying the environment or human behavior to reduce potential adverse impacts of from a natural hazard.
Mitigation Actions
  • Actions that are implemented to reduce or eliminate (mitigate) risks to persons, property or natural resources. These actions can be undertaken before and during a wildfire. Before a fire actions can include fuel treatments, creation of fuel breaks or barriers around critical or sensitive sites or resources, and vegetation modification and structural changes to increase the chance a structure will survive a wildfire with or without active protection (sometimes referred to as defensible space or the home ignition zone). Mitigation actions can also occur during response and can include mechanical and physical tasks, specific fire applications, and limited suppression actions. Such as fireline construction, and creating "black lines" through the use of controlled burnouts to limit fire spread and behavior.
Mix Ratio
  • The ratio of liquid foam concentrate to water, usually expressed as a percent. 
Mixing Chamber
  • A tube, constructed with deflectors or baffles, that mixes foam solution and air to produce tiny, uniform bubbles in a short distance (1 to 2 ft). 
Mixing Height
Mixing Layer
  • The person in charge of fire retardant mixing operations with responsibility for quantity and quality of the slurry and for the loading of aircraft. 
Mobile Radio
  • A two way radio unit on mobile apparatus (instead of base stations), usually semi-permanently attached to the apparatus. 
Mobile Weather Unit Forecast
  • A special weather forecast for a specific incident prepared by a meteorologist on site at or near the incident area. A special fire weather forecast for a specific fire prepared by a meteorologist on site at or near the fire area. 
  • The process and procedures used by all organizations, federal, state and local, for activating, assembling, and transporting all resources that have been requested to respond to or support an incident. 
Mobilization Center
  • An off-incident location at which emergency service personnel and equipment are temporarily located pending assignment, release, or reassignment. 
Mobilization Guide
  • A written description of procedures used by federal, state, and local organizations for activating, assembling, and transporting resources that have been requested to respond to or support an incident. 
  • A simplified or generalized representation of reality; a description, analogy, picture, or hypothesis to help visualize something that cannot be directly observed. 
Model Arson Law
  • Model legislation, recommended by the Fire Marshals' Association of North America and adopted in most states, dealing with the subject of arson. 
Model Fireworks Law
  • Model legislation recommended by the Fire Marshals' Association of North America and adopted by many states, regulating display of fireworks. 
Modular Airborne Firefighting System (MAFFS)
  • A manufactured unit consisting of five interconnecting tanks, a control pallet, and a nozzle pallet, with a capacity of 3,000 gallons, designed to be rapidly mounted inside an unmodified C-130 (Hercules) cargo aircraft for use in cascading retardant chemicals on wildfires. 
Moist Adiabatic Lapse Rate
  • Rate of decrease of temperature with increasing height of an air parcel lifted at saturation via adiabatic process through an atmosphere in hydrostatic equilibrium. Rate varies according to the amount of water vapor in the parcel and is usually between 2.0 and 5.0 degrees F per 1000 feet (3.6 and 9.2 degrees C per 1000 meters). 
Moisture of Extinction
  • The fuel moisture content, weighed over all the fuel classes, at which the fire will not spread. Also called extinction moisture content (EMC). 
  • A turret-type nozzle usually mounted on an engine. 
  • The orderly collection, analysis, and interpretation of environmental data to evaluate management's progress toward meeting objectives, and to identify changes in natural systems. Monitoring is also conducted on wildland fires to observe fire effects, fire behavior, or both. For example, the work done by Fire Effects Monitor (FEMO) or Field Observer (FOBS) positions. 
Monsoon Climate
  • Climate characterized by (a) a long winter-spring dry season which includes a "cold season" followed by a short "hot season" immediately preceding the rains, (b) a summer and early autumn rainy season which is usually very wet (but highly variable from year to year), and (c) a secondary maximum of temperature immediately after the rainy season.
Mop Up
  • Extinguishing or removing burning material near control lines, felling snags, and trenching logs to prevent rolling after an area has burned, to make a fire safe, or to reduce residual smoke.
    • Definition Extension: 1) Mopup is one word if used as a noun (the crew will do mopup); 2) Mop up is two words if used as a verb (mop up the fire) or as an adjective (mop up crew).
Mop Up Crew
  • A portion or all of a regular fire crew assigned to mop up work after the fire or a portion of the fire has been contained or controlled. 
Mop Up Time
  • Elapsed time from containment or control of a fire until mopup is complete. 
  • The intermingling of plant communities and their successional stages in such a manner as to give the impression of an interwoven design. 
Move Up
  • System of redistributing remaining personnel and equipment following dispatch of other forces among a network of fire stations to provide the best possible response within the fire department's direct protection area in the event of additional calls for emergency assistance. 
Move Up Method
  • Progressive method of fireline construction on a wildfire without changing relative positions in the line. Work is begun with a suitable space between workers; whenever one worker overtakes another, all of those ahead move one space forward and resume work on the uncompleted part of the line. The last worker does not move ahead until work is completed in his/her space. Forward progress of the crew is coordinated by a crew boss. 
Multi-Agency Coordinating Group (MAC Group)
  • A national, regional, or local management group for interagency planning, coordination, and operations leadership for incidents. Provides an essential management mechanism for strategic coordination to ensure incident resources are efficiently and appropriately managed in a cost effective manner. 
Multi-Agency Coordination (MAC)
  • A generalized term which describes the functions and activities of representatives of involved agencies and/or jurisdictions who come together to make decisions regarding the prioritizing of incidents, and the sharing and use of critical resources. The MAC organization is not a part of the on-scene ICS and is not involved in developing incident strategy or tactics. 
Multi-Agency Incident
  • An incident where one or more agencies assist a jurisdictional agency or agencies. May be single or unified command. 
  • A VHF/AM aircraft radio frequency (122.9 MHz) assigned by the FAA for use in air-to-air communications. 
Multijurisdiction Incident
  • An incident requiring action from multiple agencies that have a statutory responsibility for incident mitigation. In ICS these incidents will be managed under unified command. 
Multiple Fire Situation
  • High fire frequency over a short period of time in an administrative unit, usually overtaxing the normal initial attack capability of the unit. 
Multiple Fire-Day
  • In FireFamily Plus, a day with both a weather observation and a number of fires equal to or greater than that determined by the user to be a significant workload. 
Multiple Points of Origin
  • Two or more separate points of fire origins at a fire scene; strong indication of arson. 
Mutual Aid
  • Assistance in firefighting or investigation by fire agencies, without regard for jurisdictional boundaries. 
Mutual Aid Agreement
  • Written agreement between agencies and/or jurisdictions in which they agree to assist one another upon request, by furnishing personnel and equipment. 
Mutual Threat Zone
  • A geographical area between two or more jurisdictions into which those agencies would respond on initial attack. Also called mutual response zone or initial action zone. 
  • An incendiary mixture with a jelling agent used in flamethrowers and bombs. 
National Ambient Air Quality Standards (NAAQS)
  • A legal limit on the level of atmospheric contamination. The level is established as the concentration limits needed to protect all of the public against adverse effects on public health and welfare, with an adequate safety margin. Primary standards are those related to health effects. Secondary standards are designed to protect the public welfare from effects such as visibility reduction, soiling, material damage and nuisances. 
National Fire Danger Rating System (NFDRS)
  • A uniform fire danger rating system that focuses on the environmental factors that control the moisture content of fuels. 
National Fire Protection Association Standards (NFPA)
  • Standards of the National Fire Protection Association are frequently adopted by insurance agencies such as the National Board of Fire Underwriters as a basis for their regulations and used as a guide for municipal, state, or provincial laws, ordinances, and regulations. 
National Interagency Fire Management Integrated Database (NIFMID)
  • The archive of daily weather observations from WIMS. 
National Interagency Incident Management System (NIIMS)
  • An NWCG developed program consisting of five subsystems which collectively provide a total systems approach to all-risk incident management. The subsystems are: The Incident Command System, Training, Qualifications and Certification, Supporting Technologies, and Publications Management. 
National Pipe Straight Hose Thread (NPSH)
  • This is a straight (nontapered) thread standard with the same threads per inch as the appropriate size iron pipe thread. It requires a gasket to seal and is the thread standard used by most U.S. industry. Also known as National Pipe Straight Mechanical (NPSM) thread. 
National Resource Lands (NRL)
  • Public lands administered by the Bureau of Land Management, U.S. Department of the Interior. 
National Response Plan
  • A plan that integrates federal government domestic prevention, preparedness, response, and recovery plans into one all-discipline, all-hazard plan. 
National Standard Thread (NH)
  • Abbreviated (NH) for national hose. Specifically defined screw thread used on fire hose couplings. 
Native Species
  • A species which is a part of the original fauna or flora of the area in question. 
Natural Barrier
  • Any area where lack of flammable material obstructs the spread of wildfires. 
Natural Fuels
  • Fuels resulting from natural processes and not directly generated or altered by land management practices. 
Near Miss
  • Any potential accident which, through prevention, education, hazard reduction, or luck, did not occur. 
  • An 8-character identifier assigned by NESDIS that becomes the RAWS identification number for use with the GOES satellite. 
Net Value Change (NVC)
  • The sum of the changes in the value of natural resources affected by a fire. The basis for computing NVC is each resource's fire-induced value change (pluses and minuses) as computed and expressed on a per unit basis. 
Neutral Atmosphere
Night (Aviation)
  • The time between the end of evening civil twilight and the beginning of morning civil twilight, as published in the American Air Almanac, converted to local time. 
Nitrogen Dioxide (NO2)
  • The result of nitric oxide combining with oxygen in the atmosphere. A major component of photochemical smog. 
Nitrogen Oxide (NO)
  • Product of combustion from transportation and stationary sources and a major contributor to acid deposition and the formation of ground level ozone in the troposphere. 
  • Trade name for a fire resistant synthetic material used in the manufacturing of flight suits and pants and shirts used by firefighters. Aramid is the generic name. 
Non-attainment Area
  • An area identified by an air quality regulatory agency through ambient air monitoring (and designated by the Environmental Protection Agency), that presently exceeds federal ambient air standards. 
  • Material unlikely to burn when exposed to flame under most conditions. 
Nonprecision Approach Procedure
  • Standard aircraft instrument approach procedure in which no electronic glide slope is provided. 
Nonstatistical Fire
  • Any fire not posing a threat to resources or property of the jurisdictional agency, regardless of whether action was taken by the agency. 
Normal Fire Season
  1. A season when weather, fire danger, and number and distribution of fires are about average.
  2. Period of the year that normally comprises the fire season based on historical fire occurrence. 
Normalized Difference Vegetation Index (NDVI)
  • A satellite observation-derived value that is sensitive to vegetative growth, measured at 1.1 km (0.6 mile) spatial and 1 week temporal scales. 
Notice to Airmen (NOTAM)
  • Notice identified as either a NOTAM or Airmen Advisory containing information concerning the establishment, condition, or change in any component of, or hazard in, the National Airspace System, the timely knowledge of which is essential to personnel concerned with flight operations. 
Nozzle Aspirated Foam System
  • A foam generating device that mixes air at atmospheric pressure with foam solution in a nozzle chamber. 
Nozzle Operator
  • A person assigned to operate a fire hose nozzle, usually on a handline. 
NWCG Standard
  • A defined behavior, action, process, or equipment type, agreed upon by the National Wildfire Coordinating Group for wildland fire performance, and is necessary to meet consistent, interagency fire management activities.
  1. A description of a desired condition; quantified and measured, and where possible, with established time frames for achievement.
  2. Specific, achievable, measurable, time-limited results to be achieved through land management practices, either through a description of a desired condition or the degree of desired change in an attribute. 
Observation Time
  • Time of day required to record meteorological data at a fire danger station. 
Obstruction to Vision
  • Condition in which obscuring phenomenon restricts horizontal visibility to six statute miles (10 km.) or less. 
Occluded Front or Occlusion
  • The front that is formed when and where a cold front overtakes a warm front or a stationary front. 
Occurrence Index (OI)
  • A number in the National Fire Danger Rating System related to potential fire incidence within a protection unit. 
Off-road Vehicle (ORV)
  • Any motorized vehicle designed for, or capable of, cross-country travel on or immediately over land, water, sand, snow, ice, marsh, swampland, or other terrain. 
  • Non-compensable time, e.g., eating, sleeping or other activities of a personal nature.
Off-Site/Remote Assignment
  • Work performed by an individual employee in support of an incident while remaining at the employee’s duty station or other designated off-site location.
  • The ICS title for personnel responsible for the Command Staff positions of Safety, Liaison, and Information. 
Offshore Flow
  • Wind blowing from land to water. 
  • Status of a federal casual or federal regular government employee used for timekeeping purposes. An employee will be considered off duty and time spent in an on-call status shall not be considered hours of work if: 1) The employee is allowed to leave a telephone number or to carry an electronic device for the purpose of being contacted, even though the employee is required to remain within a reasonable call-back radius; or 2) The employee is allowed to make arrangements such that any work which may arise during the on-call period will be performed by another person. (Reference 5 CFR 551.431(b) (1-2)). Specific state pay guidelines for non-pay status shall apply for state employees.
  • Time of actual work, ordered standby, or compensable travel with a specific start and ending time.
One Lick Method
  • A progressive system of building a fireline on a wildfire without changing relative positions in the line. Each worker does one to several "licks", or strokes, with a given tool and then moves forward a specified distance to make room for the worker behind.
One-hour Timelag Fuel Moisture (1-h TL FM)
  • Moisture content of one-hour timelag fuels. 
One-hour Timelag Fuels
  • Fuels consisting of dead herbaceous plants and roundwood less than about one-fourth inch (6.4 mm) in diameter. Also included is the uppermost layer of needles or leaves on the forest floor. 
One-hundred Hour Timelag Fuel Moisture (100-h TL FM)
  • The moisture content of the 100-hour timelag fuels. 
One-hundred Hour Timelag Fuels
  • Dead fuels consisting of roundwood in the size range of 1 to 3 inches (2.5 to 7.6 cm) in diameter and very roughly the layer of litter extending from approximately three-fourths of an inch (1.9 cm) to 4 inches (10 cm) below the surface. 
One-thousand Hour Timelag Fuel Moisture (1,000-h TL FM)
  • The moisture content of the 1,000-hour timelag fuels. 
One-thousand Hour Timelag Fuels
  • Dead fuels consisting of roundwood 3-8 inches in diameter and the layer of the forest floor more than about 4 inches below the surface. 
Onshore Flow
  • Wind blowing from water to land. 
Open Burning
  • Burning of any fuel outdoors without the use of mechanical combustion enhancements. 
Open Line
  • Refers to open fire front where no line has been constructed. 
Operating Weight
  • For helicopters, the equipped weight plus weight of the crew and fuel. 
Operational Control
  • The exercise of authority over initiating, conducting, or terminating any operation. Often associated with aviation operations. 
Operational Period
  • The period of time scheduled for execution of a given set of tactical actions as specified in the Incident Action Plan. Operational Periods can be of various lengths, although usually not over 24 hours. 
Operational Tempo
  • The speed and intensity of actions relative to the speed and intensity of the unfolding events in the operational environment. 
Operations Coordination Center (OCC)
  • Primary facility of the Multi-agency Coordination System (MACS); houses staff and equipment necessary to perform the MACS function. 
Operations Section
  • The section responsible for all tactical operations at the incident. Includes branches, divisions and/or groups, task forces, strike teams, single resources and staging areas. 
  • A circular holding pattern of an aircraft around a fixed location often related to a wildland fire. For example, the circular pattern of an airtanker in the vicinity of a wildland fire, waiting to make a retardant drop. 
Ordered Standby
  • An employee is on duty, and time spent on standby duty is hours of work if, for work-related reasons, the employee is restricted by official order to a designated post of duty and is assigned to be in a state of readiness to perform work with limitations on the employee’s activities so substantial the employee cannot use the time effectively for his or her own purposes. A finding that an employee’s activities are substantially limited may not be based on the fact that an employee is subject to restrictions necessary to ensure that the employee will be able to perform his or her duties and responsibilities, such as restrictions on alcohol consumption or use of certain medications (5 CFR 551.431(a) (1)).
Organic Matter
  • That fraction of the soil that includes plant and animal residues at various stages of decomposition, cells and tissues of soil organisms, and substances synthesized by the soil population. 
Organic Soil
  • Any soil or soil horizon containing at least 30% organic matter (e.g., muck, peat). 
  • Pertaining to, or caused by mountains. 
  • Photograph obtained from the orthogonal (i.e., horizontal) projection of a correctly oriented stereoscopic model formed by two overlapping aerial photographs; an orthophoto is free of tilt and relief displacements. 
Orthophoto Maps
  • Aerial photographs corrected to scale such that geographic measurements may be taken directly from prints. They may contain graphically emphasized geographic features and may be provided with overlays of such features as: water systems, facility location, etc. 
Osborne Firefinder
  • A sighting device used by lookouts to determine the horizontal bearing and sometimes the vertical angle of a fire from a lookout. 
Other Training Which Supports Development of Knowledge and Skills
  • Courses defined as containing supplemental knowledge and skills not required for safe and tactical operations success on a wildfire.
    • Synonym: Recommended Training
Out-of-Service Resources
  • Resources assigned to an incident but unable to respond for mechanical, rest, or personal reasons. 
Outside Aid
  • Firefighting assistance given to adjacent areas and nearby communities by contract or other agreement that covers conditions and payment for assistance rendered and services performed. Contrasted to mutual aid, in which neighboring firefighting organizations assist each other without charge. 
Outside Diameter (OD)
  • External diameter of a cylinder or tube, conductor, or coupling as distinguished from the internal diameter. 
  • Fire department procedure of inspecting premises after extinguishment of fire, to insure that fire is completely out and unable to rekindle before returning control to owner or occupants. 
  • Personnel assigned to supervisory positions, including incident commander, command staff, general staff, branch directors, supervisors, unit leaders, managers and staff. 
  1. Gross vehicle weight (GVW) in excess of the gross vehicle weight rating (GVWR) specified by the chassis manufacturer. Also an excess of weight over the gross vehicle axle weight rating (GAWR) specified by the chassis manufacture.
  2. A situation that taxes an operational system to the limit of its functional capabilities. Such as too many fires for an individual unit to handle (fire overload), or too many orders for an individual dispatch center to process (dispatch overload). 
Overwintering Fire
  • A fire that persists through the winter months until the beginning of fire season. 
  • Process during which oxygen combines with another substance. 
  • The portion of a chemical mixture or compound which furnishes oxygen for burning a fuel or propellant, creating an oxide. 
Pack Test
  • Used to determine the aerobic capacity of fire suppression support personnel and assign physical fitness scores. The test consists of walking a specified distance, with or without a weighted pack, in a predetermined period of time, with altitude corrections. 
Packing Ratio
  • The fraction of a fuel bed occupied by fuels, or the fuel volume divided by bed volume. 
Panoramic Photograph
  • Photographs from a lookout point, bearing azimuth and vertical angle scales, to assist in locating fires with a firefinder. 
  • Anything intentionally dropped, or intended for dropping, from any aircraft by parachute, by other retarding devices, or by free fall. 
Parallel Attack
  • Method of fire suppression in which fireline is constructed approximately parallel to, and just far enough from the fire edge to enable workers and equipment to work effectively, though the fireline may be shortened by cutting across unburned fingers. The intervening strip of unburned fuel is normally burned out as the control line proceeds but may be allowed to burn out unassisted where this occurs without undue delay or threat to the fireline. 
Parallel Lane Technique
Parallel Pumping
  • Procedure by which the flow from two fire pumps is combined into one hose line. 
Parallel Tandem Pumping
  • Procedure by which the flow from two fire pumps is combined into a third pump. 
Partial Risk
  • Part of the National Fire Danger Rating System (NFDRS). Contribution of a specific source to human-caused risk, derived from the daily activity level assigned a risk source and its risk source ratio. 
Partial Risk Factor
  • Part of the National Fire Danger Rating System (NFDRS). Contribution to human-caused risk made by a specific risk source; a function of the daily activity level assigned that risk source and the appropriate risk source ratio. 
Partial-thickness Burn
  • A burn where the outer layer of skin is burned through and the second layer of skin (dermis) is damaged and is typically, a painful injury. Burns of this type cause reddening, blistering, and a mottled appearance. (also called Second Degree Burn).
Particle Size
  • The size of a piece of fuel, often expressed in terms of size classes. 
Particulate Matter
  • Any liquid or solid particles. "Total suspended particulates", as used in air quality, are those particles suspended in or falling through the atmosphere. They generally range in size (diameter) from 0.1 to 100 micrometers.
Parts of a Fire
  • Different areas of the fire usually determined by the predominant direction of fire spread and delineated from the fastest moving area (head) to the slowest moving area (base or tail). The most rapidly moving portion is designated the head of the fire, the adjoining portions of the perimeter at right angles to the head are known as the flanks, and the slowest moving portion is known as the rear or the base of the fire. 
Passenger, Authorized
Passenger, Official
  • The following categories of personnel are official passengers: Officers and employees of the federal government traveling on official business. Members of Congress and employees of congressional committee staffs whose work relates to the agency’s programs. Non-federal passengers when engaged in missions which enhance accomplishment of an agency program such as personnel of cooperating state, county, or local agencies; representatives of foreign governments; and contractors’ representatives to include those employed by such agencies; and private citizens. Source: NWCG Standards for Helicopter Operations, PMS 510.
Passenger, Unauthorized
  • All personnel who are not official or unofficial passengers are considered unauthorized passengers and are not authorized to be transported in any aircraft owned or operated by or on behalf of the government. Source: NWCG Standards for Helicopter Operations, PMS 510.
Passive Crown Fire
  • A fire in the crowns of trees in which trees or groups of trees torch, ignited by the passing front of the fire. The torching trees reinforce the spread rate, but these fires are not basically different from surface fires. 
Patch Burning
  • Burning in patches to prepare sites for group planting or sowing or to form a barrier to subsequent fires. 
  1. To travel over a given route to prevent, detect, and suppress fires. Includes interaction with the public for wildland fire prevention and educational purposes.
  2. To go back and forth vigilantly over a length of control line during and/or after construction to prevent breakovers, suppress spot fires, and extinguish overlooked hotspots.
  3. A person or group of persons who carries out patrol actions. 
Patrol Time
  • Elapsed time from completion of original mopping up until the fire is declared to be extinguished. 
  • The distribution of an aerially delivered retardant drop on the target area in terms of its length, width, and momentum (velocity x mass) as it approaches the ground. The latter determines the relative coverage level of the fire retardant on fuel within the pattern. 
Pattern Clusters
  • A group of indicators in a close proximity, of the same or different categories, that exhibit consistent directional values. 
  • Weight of passengers and/or cargo being carried by an aircraft. 
Peak Fire Season
  • That period of the fire season during which fires are expected to ignite most readily, to burn with greater than average intensity, and to create damages at an unacceptable level. 
Peak Monthly Average
  • Highest monthly average of human-caused fires calculated for a protection unit. 
Peak Wind
  • The greatest 5-second average wind speed during the previous hour that exceeded 25 knots. 
Peak Wind Direction
  • Direction at Peak Wind Speed. 
Peak Wind Speed
  • Maximum wind speed during the previous 60 minutes. 
  • Passage of liquid through a porous body, as movement of water through soil. 
Perennial Plant
  • A plant that lives for more than two growing seasons. For fire danger rating purposes, biennial plants are classed with perennial plants. 
Performance Chart
  • A chart, table, or graph provided by the manufacturer for use in determining an aspect of helicopter and fixed-wing aircraft performance. 
Performance Oriented Objectives
  • On-the-job performance enhancement is a result of online training. Performance oriented objectives or learning objectives for this training is developed, agreed to, and tested to ensure skill transfer. The purpose of learning objectives is to define the type of learning or performance outcomes that will occur at the conclusion of instruction and how learning will be assessed. Both objectives and performance outcomes should be written as precisely as possible in order to best determine whether they have been achieved. 
  • A short term for "permanently frozen ground"; any part of the earth's crust, bedrock, or soil mantle that remains below 32? F (0? C) continuously for a number of years.
Perpendicular Lane Technique
Personal Protective Equipment (PPE)
  • That equipment and clothing required to mitigate the risk of injury from or exposure to hazardous conditions encountered during the performance of duty. PPE includes but is not limited to: fire resistant clothing, hard hat, flight helmets, shroud, goggles, gloves, respirators, hearing protection, chainsaw chaps, and shelter. 
Personnel Accountability
  • The ability to account for the location and welfare of personnel, accomplished when supervisors ensure that the ICS principles and processes are functional and personnel are working within these guidelines. 
Photo Point
Piling and Burning
  • Piling slash resulting from logging or fuel management activities and subsequently burning the individual piles. 
Pilot Balloon Operation (PIBAL)
  • A method of determining winds aloft by periodically reading the elevation and azimuth angles of a theodolite, usually at one-minute intervals, while tracking the ascent of a small free-lift balloon. A PIBAL is commonly used for constructing a wind profile. 
  • Pilot responsible for the operation and safety of an aircraft during flight time. 
  • Navigation of aircraft by visual reference to landmarks. 
Pin Flags
Pin Lug Coupling
  • A hose coupling with one or more cylindrical studs on its outside rim. The studs allow the use of a spanner wrench to tighten the coupling. 
Pincer Action
  • Direct attack around a fire in opposite directions by two or more attack units. Usually conducted from the fire's tail to head. 
Ping-Pong Ball System
  • Mechanized method of dispensing DAIDs (Delayed Aerial Ignition Devices) at a selected rate. The DAIDs are polystyrene balls, 1.25 inches in diameter, containing potassium permanganate. The balls are fed into a dispenser, generally mounted in a helicopter, where they are injected with a water-glycol solution and then drop through a chute leading out of the helicopter. The chemicals react thermally and ignite in 25-30 seconds. The space between ignition points on the ground is primarily a function of helicopter speed, gear ratio of the dispenser, and the number of chutes used (up to four). 
Pithy Stalk
Plan of Attack
  • The selected course of action and organization of personnel and equipment in fire suppression, as applied to a particular fire or to all fires of a specific type. 
Planetary Boundary Layer
  • That part of the earth's lower atmosphere that is directly influenced by the presence of the earth's surface and responds to surface forcings such as fronts, friction, evapotranspiration and convective mixing. 
Planned Ignition
Planning Interval
  • Period of time between scheduled planning meetings. 
Planning Meeting
  • A meeting held regularly throughout the duration of an incident, to select specific strategies and tactics for incident control operations and to plan for needed service and support. On larger incidents, the planning meeting is a major element in the development of the Incident Action Plan. 
Planning Section
  • Responsible for the collection, evaluation, and dissemination of tactical information related to the incident, and for the preparation and documentation of incident action plans. The section also maintains information on the current and forecasted situation, and on the status of resources assigned to the incident. Includes the situation, resource, documentation, and demobilization units, as well as technical specialists. 
Plastic Sphere Dispenser (PSD)
Plow Line
  • A convection column generated by combustion (of wildland fuel). 
Plume Rise
  • How high above the level of release an emission plume rises. 
Plume-dominated Wildland Fire
  • A wildland fire whose activity is determined by the convection column. 
  • Particulate matter of mass median aerodynamic diameter (MMAD) less than or equal to 10 micrometers. 
  • Particulate matter of mass median aerodynamic diameter (MMAD) less than or equal to 2.5 micrometers. 
Pocket Weather Meter
  • A handheld electronic device that measures temperature, humidity, wind speed, and possibly other atmospheric variables, depending on brand and model.
Pockets of a Fire
  • Unburned indentations in the fire edge formed by fingers or slow burning areas. 
Point of Attack
  • That part of the fire on which work is started when suppression crews arrive. 
Point of Origin
  • The exact physical location within the Ignition Area where a heat source and the local fuel interact, resulting in a fire. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
    • Definition Extension: The "exact" location of a point of origin is rarely found due to the rapid destruction and/or dislocation of the first fuels ignited during the combustion process.
Point of Origin on Unprotected Land
  • Point of Origin of an incident for which NO fire agency has been assigned as the protecting unit.
    • Business Rule: A user will be selecting yes/no = true/false.
Point Source
  • A permanent source of air pollution that can be distinctly identified such as a smokestack. 
Point Source Fire Predictions
  • Predictions that apply to an initiating fire burning during a time when conditions have been relatively constant, or where it can be assumed that the fire will maintain a basically elliptical shape. 
Point/Zone Protection
  • A wildfire response strategy which protects specific assets or highly valued resources from the wildfire without directly halting the continued spread of the wildfire. 
    • Definition Extension:  1) Points or zones being protected may be communities, individual structures, areas of high resource value, etc.  2) Continued wildfire spread may be desirable in order to achieve management objectives or may be inevitable due to extreme burning conditions, safety concerns, or other limitations.  
    • See also: Monitoring; ConfineContained; Suppression
  • Unit of fluid viscosity in fire retardant, defined as tangential force per unit area (dynes/square centimeter) required to maintain unit difference in velocity (1 centimeter/second) between two parallel planes separated by 1 cm of fluid (1 poise=1 dyne-second/cubic centimeter). 
Portable Pump
  • Small gasoline-driven pump that can be carried to a water source by one or two firefighters or other conveyance over difficult terrain. 
  • Container, either with rigid frame or self supporting, which can be filled with water or fire chemical mixture from which fire suppression resources can be filled. It can also be a source for charging hose lays from portable pumps or stationary engines. 
Position Currency Requirement
  • The requirement to perform satisfactorily in a specified position within the last five years (three years for aviation and expanded dispatch positions) in order to maintain qualification for the position. 
Position Performance Assignment
  • An assignment in which an individual is being evaluated for tasks found in the position task book. 
Position Task Book (PTB)
  • A document listing the performance requirements (competencies and behaviors) for a position in a format that allows for the evaluation of individual (trainee) performance to determine if an individual is qualified in the position. Successful performance of PTB tasks, as observed and recorded by a qualified evaluator, will result in a recommendation to the trainee's home unit that the individual be certified in the position. 
Positive Displacement Pump
  • A pump which moves a specified quantity of water through the pump chamber with each stroke or cycle; it is capable of pumping air, and therefore is self-priming, but must have pressure relief provisions if plumbing or hoses have shut-off nozzles or valves . Gear pumps and piston pumps are common examples of this type. 
  • A level of certainty that is feasible but does not rise to the level of probable. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
    • Definition Extension: If two or more hypotheses are equally likely and no hypothesis rises to the level of probable, then the level of certainty must be "possible" and the cause of the fire would be "undetermined".
Potato Roll
  • Quick method of rolling hose for pick up; hose is rolled as a ball of string. 
Pounds per Square Inch (PSI)
  • Measurement of pressure (e.g., pump pressure, nozzle pressure, friction loss in hose, pressure loss or gain due to elevation). 
  • In the 1978 version of NFDRS, the herbaceous stage approximately 30 days prior to green-up. 
  • A planned, systematic procedure for collecting, recording, and evaluating prefire and fire management intelligence data for a given planning unit or preattack block. The planning phase is usually followed by a construction and development program integrated with other resources and activities. 
Preattack Block
  • Unit of wildland delineated by logical and strategic topographic features for preattack planning. 
Preattack Planning
  • Within designated blocks of land, planning the locations of firelines, fire camps, water sources, and helispots; planning transportation systems, probable rates of travel, and constraints of travel on various types of attack units; and determining what types of attack units likely would be needed to construct particular firelines, their probable rate of fireline construction, and topographic constraints on fireline construction. 
Precautionary Landing
  • A landing necessitated by apparent impending failure of engines, systems, or components which makes continued flight unadvisable. 
  • Any or all forms of water particles, liquid or solid, that fall from the atmosphere and reach the ground. 
Precipitation Amount
  • The total amount of precipitation that occurred within the preceding 24-hour period. 
Precipitation Duration
  • Time, in hours and fraction of hours, that a precipitation event lasts. More precisely, for fire danger rating purposes, the length of time that fuels are subjected to liquid water. 
Precipitation Gauge
  • Device commonly used to collect and permit measurement of any form of rain and snow sufficiently heavy to have fallen to the earth's surface. Also known as a rain gauge. 
Precision Approach Procedure
  • A standard instrument approach procedure for fixed-wing aircraft in which an electronic glide slope is provided, such as ILS and PAR. 
Precision Approach Radar (PAR)
  • Blind landing in which the aircraft is observed from the ground by means of radar and directed along a suitable glide path by instructions radioed to the pilot. 
  • Hard suction hose or discharge hose carried connected to pump, eliminating delay occasioned when hose and nozzles must be connected and attached at fire. 
Predictive Services
  • Those Geographic Area and National-level fire weather or fire danger services and products produced by wildland fire agency meteorologists and intelligence staffs in support of resource allocation and prioritization. 
Preignition Combustion Phase
  • Thermal or chemical decomposition of fuel at an elevated temperature. This is the pre-combustion stage of burning during which distillation and pyrolysis predominate. Heat energy is absorbed by the fuel which, in turn, gives off water vapor and flammable tars, pitches, and gases. These ignite when mixed with oxygen to initiate the flaming combustion phase. 
Preignition Phase
  • Preliminary phase of combustion in which fuel elements ahead of the fire are heated, causing fuels to dry. Heat induces decomposition of some components of the wood, causing release of combustible organic gases and vapors. 
  1. Activities that lead to a safe, efficient, and cost-effective fire management program in support of land and resource management objectives through appropriate planning and coordination.
  2. Mental readiness to recognize changes in fire danger and act promptly when action is appropriate.
  3. The range of deliberate, critical tasks, and activities necessary to build, sustain, and improve the capability to protect against, respond to, and recover from domestic incidents.
Preparedness Level
  • Increments of planning and organizational readiness dictated by burning conditions, fire activity, and resource availability.
    • Definition Extension:  Response and support to non-fire incidents requiring a significant commitment of resources may also affect Preparedness Levels.
Preparedness Plan
  • A written plan providing for timely recognition of approaching critical fire situations, priority setting, the deployment of forces, and other actions to respond to those situations. 
Prescribed Burning
  • Application of prescribed fire. 
Prescribed Fire
Prescribed Fire Burn Plan
  • A plan required for each fire application ignited by management. Plans are documents prepared by qualified personnel, approved by the agency administrator, and include criteria for the conditions under which the fire will be conducted (a prescription). Plan content varies among the agencies.
Prescribed Fire Module
  • A team of skilled and mobile personnel dedicated primarily to prescribed fire management that can ignite, hold and monitor prescribed fires.
Prescribed Fire Plan
  • A plan for each prescribed fire, prepared by qualified personnel, approved by the agency administrator, which includes criteria for the conditions under which the fire will be conducted (a prescription).
  • In the context of wildland fire, a prescription is measurable criteria that define conditions under which a prescribed fire may be ignited. Prescriptions may also be used to guide selection of management responses to wildfire to define conditions under which management actions are most likely to achieve incident management objectives. Prescription criteria typically describe environmental conditions such as temperature, humidity and fuel moisture, but may also include safety, economic, public health, geographic, administrative, social, or legal considerations. 
Pressure Gradient
  • The difference in atmospheric pressure between two points on a weather map. That is, the magnitude of pressure difference between two points at sea level, or at constant elevation above sea level. Wind speed is directly related to pressure gradient. If distance between constant pressure lines is reduced by one-half, wind speed will be doubled. Conversely, if distance between lines is doubled, wind speed will be reduced by one-half. 
Pressure Loss
  • Reduction in water pressure between a pump or hydrant and a nozzle due to expenditure of pressure energy required to move water through a hose; includes losses due to back pressure, friction loss, elevation loss, and/or losses in fittings. 
Pressure Pattern
  • The distribution of surface atmospheric pressure features over an area of the earth as shown on a weather map. Surface pressure features include lines of constant pressure (isobars), highs, lows, and pressure gradient. The pressure pattern is directly related to wind speeds and directions at specific locations. 
  • Activities in advance of fire occurrence to ensure effective suppression action. Includes planning the organization, recruiting and training, procuring equipment and supplies, maintaining fire equipment and fire control improvements, and negotiating cooperative and/or mutual aid agreements. 
  • The use of water, foam or retardant along a control line in advance of the fire. Often used where ground cover or terrain is considered best for control action. 
  • Activities directed at reducing the incidence of fires, including public education, law enforcement, personal contact, and reduction of fuel hazards (fuels management). Actions to avoid an incident, to intervene for the purpose of stopping an incident from occurring, or to mitigate an incident's effect to protect life and property. Includes measures designed to mitigate damage by reducing or eliminating risks to persons or property, lessening the potential effects or consequences of an incident. 
Prevention of Significant Deterioration (PSD)
  • A program identified by the Clean Air Act to prevent air quality and visibility degradation and to remedy existing visibility problems. Areas of the country are grouped into 3 classes which are allowed certain degrees of pollution depending on their uses. National Parks and Wilderness Areas meeting certain criteria are "Class I" or "clean area" in that they have the smallest allowable increment of degradation. 
Prevention Team
  • Provides support to fire prevention and wildland fire educational needs preceding and during periods of high wildland fire danger or prescribed fire activity. The teams provide assistance to wildland fire managers with coordination of fire loss mitigation efforts with public, state or local agencies.
  • Filling pump with water when pump is taking water not under a pressure head. Necessary for centrifugal pumps. 
  • A number representing the chance that a given event will occur. The range is from 0% for an impossible event, to 100% for an inevitable event. 
Probability Forecast
  • A forecast of the probability of occurrence of one or more of a mutually exclusive set of weather contingencies as distinguished from a series of categorical statements. 
Probability of Ignition
  • The chance that a firebrand will cause an ignition when it lands on receptive fuels. 
Procurement Office
  • Agency personnel with specific delegation of procurement authority, acting within the limits of agency policy of said authority.
Procurement Unit
  • Functional unit within the Finance/Administration Section responsible for managing all financial matters pertaining to vendor contracts. 
Progressive Hose Lay
  • A hose lay in which double shutoff wye (Y) valves are inserted in the main line at intervals and lateral lines are run from the wyes to the fire edge, thus permitting continuous application of water during extension of the lay. 
Progressive Method of Line Construction
  • A system of organizing workers to build fireline in which they advance without changing relative positions in line. 
Project Activity Level (PAL)
  • An application of fire danger rating to support regulation of contractors involved in land management activities for fire prevention purposes in California. 
  • A device that adds a predetermined amount of foam concentrate to water to form foam solution. 
Protected Lands
  • Areas for which a fire protection organization has the primary responsibility for managing a wildfire and directing fire management actions. Such responsibility may be authorized by law, contract, or personal interest of the firefighting agent (e.g., a lumber operator). Note: Several agencies or entities may have some basic responsibilities (e.g., private owner) without being known as the fire organization having primary responsibility. 
Protected Side
Protecting Agency
Protection Area
  1. That area for which a particular fire protection organization has the primary responsibility for attacking an uncontrolled fire and for directing the suppression action. Such responsibility may develop through law, contract, or personal interest of the firefighting agent (e.g., a lumber operator). Several agencies or entities may have some basic responsibilities (e.g., private owner) without being known as the fire organization having direct protection responsibility. 
  2. A geographical area which is administratively defined and for which organized fire suppression activities are formally planned.
Protection Boundary
  • The exterior perimeter of an area within which a specified fire agency has assumed a degree of responsibility for wildland fire control. It may include land in addition to that for which the agency has jurisdiction or contractual responsibility. 
  • General name for instruments designed to determine the moisture content of air. A psychrometer consists of dry- and wet-bulb thermometers that give the dry- and wet-bulb temperatures, which in turn are used to determine relative humidity and dew point. 
Public Aircraft
  • Aircraft used only in the service of a government or a political subdivision. It does not include any government-owned aircraft engaged in carrying persons for commercial purposes. 
  • A combination chopping and trenching tool widely used in fireline construction, which combines a single-bitted axe blade with a narrow adze-like trenching blade fitted to a straight handle. 
Punky Material
  • Partly decayed material, such as old wood, in which fire can smolder unless it is carefully mopped up and extinguished. A good receptor for firebrands when dry. 
  • The thermal or chemical decomposition of fuel at an elevated temperature. This is the preignition combustion phase of burning during which heat energy is absorbed by the fuel which, in turn, gives off flammable tars, pitches, and gases. 
  • A mixture of chemicals designed to produce heat, light, gas, smoke or noise. 
  • Mapping unit which defines an area in terms of longitude and latitude distance. Two common scales are 1:24,000 quadrangles, which are 7.5' longitude x 7.5' latitude, and 1:62,500 quadrangles, which are 15' longitude x 15' latitude. 
Qualification Sheet
  • A written resume of an expert witness used to show that expert?s sufficient special expertise in the field. 
Qualifications and Certification
  • This subsystem of NIIMS provides recommended qualification and certification for those personnel responding to an incident regionally or nationally, allowing for the development of local minimum standards to meet local needs. Standards typically include training, experience, and physical fitness.
Qualified Non-Crew Member
  • An individual, other than a member of the crew, aboard an aircraft whose presence is required to perform, or is associated with the performance of, a governmental function.   Source: NWCG Standards for Helicopter Operations, PMS 510.
Qualitative Risk Assessment
  • Qualitative risk assessment is the application of judgment based in knowledge and experience when assessing wildfire risk, the potential for ignitions and recommendations regarding possible ways to mitigate the risk.
Quantitative Risk Assessment
  • Quantitative risk assessments provide a method by which we can calculate risk based on measurements or estimates of various risk components such as likelihood of fire occurrence, intensity of fire should it occur, and susceptibility to fire of the various values being evaluated.
  • A magnetic bearing extending from a ground-based navigational system, providing airborne navigation information. 
Radiant Burn
  • A thermal trauma that maybe a superficial, partial thickness or full thickness burn. 
Radiant Heat Flux
  • The amount of heat flowing through a given area in a given time, usually expressed as calories/square centimeter/second. 
  1. Propagation of energy in free space by virtue of joint, undulatory variations in the electric or magnetic fields in space, (i.e., by electromagnetic waves).
  2. Transfer of heat in straight lines through a gas or vacuum other than by heating of the intervening space. 
Radio Cache
  • A cache may consist of a number of portable radios, base station, and, in some caches, a radio repeater that is stored in a predetermined location for dispatch to incidents. 
Radio Fix
  • Determination of position by one or more radio navigational aids. 
  • A device carried aloft by a balloon equipped with measuring instruments that automatically convert temperature, pressure, and humidity data into electrical impulses and transmit this information to a ground recorder.
Railroad Fire
  • A fire resulting from any operation or activity of a railroad, except smoking. 
Range Fire
  • Any wildfire on rangeland. 
  • Technique of landing specifically trained and certified firefighters from hovering helicopters; involves sliding down ropes with the aid of friction-producing devices. 
Rate of Spread
  • The relative activity of a fire in extending its horizontal dimensions. It is expressed as rate of increase of the total perimeter of the fire, as rate of forward spread of the fire front, or as rate of increase in area, depending on the intended use of the information. Usually it is expressed in chains or acres per hour for a specific period in the fire's history.
Rate of Spread Factor
  • A factor usually on a scale of 1 to 100 which represents a relative rate of forward spread for a specific fuel condition and fixed weather conditions (or fuel model). Factors can be used as multipliers, arguments for entering tables, or provide a ratio of values between two fuels. 
Rate of Spread Meter
  • A device that computes the probable rate of spread of a fire for different combinations of fuel moisture, wind speed, and other selected factors. 
Rating Period
  • Part of the National Fire Danger Rating System (NFDRS). The period of time during which a fire danger rating value is considered valid or representative for administrative or other purposes. Normally it is 24 hours extending from midnight to midnight. 
  • Method of upper-air observation consisting of an evaluation of the wind speed and wind direction, temperature, pressure, and relative humidity aloft by means of a balloon-borne radiosonde tracked by a radar or radio direction-finder. 
  • Confirmation through the re-issuance of an incident qualification card that an individual has regained qualifications for a specified position that was lost through a lack of current experience. A key component in the certification or re-certification process is the subjective evaluation by the appropriate agency official of an individual's capability to perform in a position. 
Reaction Intensity
  • The rate of heat release, per unit area of the flaming fire front, expressed as heat energy/area/time, such as Btu/square foot/minute, or Kcal/square meter/second.
  1. Condition or degree of being completely ready to cope with a potential fire situation.
  2. Mental readiness to recognize changes in fire danger and act promptly when action is appropriate. 
Rear (Of a Fire)
  1. That portion of a fire spreading directly into the wind or down slope.
  2. That portion of a fire edge opposite the head.
  3. Slowest spreading portion of a fire edge. Also known as a heel of a fire. 
Reason For Responding To Incident On Unprotected Land
  • The rationale an agency responded to an incident where the point of origin is on unprotected land.
    • Business Rule:  A user can select from just one value - Threat. The responding organization determines threat to protected lands.
Reasonably Available Control Measures (RACM)
  • Control measures developed by EPA which apply to residential wood combustion, fugitive dust, and prescribed and silvicultural burning in and around "moderate" PM-10 non-attainment areas. RACM is designed to bring an area back into attainment and uses a smoke management program which relies on weather forecasts for burn/no-burn days. 
  1. Repeat burning of an area over which a fire has previously passed, but left fuel that later ignites when burning conditions are more favorable.
  2. An area that has reburned. 
Reconnaissance (RECON)
  • To examine a fire area to obtain information about current and probable fire behavior and other related fire suppression information. 
  • Individuals within ICS organizational units who are responsible for recording information. Recorders may be found in planning, logistics and finance/administration units. 
  1. The increase in fuel moisture as a result of increased relative humidity, usually occurring overnight.
  2. The general term used to describe the maximum overnight value of atmospheric relative humidity. 
Recreation Fire
  • A fire resulting from recreational use, except smoking. 
Recurrent Training
  • Training scheduled at established intervals that has been identified as required training in order to maintain position currency. 
Red Flag Warning
  • Term used by fire weather forecasters to alert forecast users to an ongoing or imminent critical fire weather pattern.
  • A frame on which hose is wound, now chiefly used for "booster" or small hose (3/4- or l-inch hose) (19 or 25 mm) supplied by a water tank on the apparatus; also, a hand-drawn 2-wheel frame for 2-1/2 inch (64 mm) hose used in industrial plants. 
Reference Point(s)
Regional Haze
  • Visibility impairment caused by the cumulative air pollutant emissions from numerous sources over a wide geographic area. 
Regular Government Employee
  • Includes any individual hired under authorities other than the AD Pay Plan for Emergency Workers. Federal general schedule and federal wage system employees are included in this category.
  • Efforts undertaken within three years of a wildland fire to repair or improve fire damaged lands unlikely to recover to a management approved conditions or to repair or replace minor facilities damaged by fire.
  • Re-ignition due to latent heat, sparks, or embers or due to presence of smoke or steam. 
Relative Greenness (RG)
  • An NDVI-derived image of vegetation greenness compared to how green it has been historically.
Relative Humidity (RH)
  • The ratio of the amount of moisture in the air, to the maximum amount of moisture that air would contain if it were saturated. The ratio of the actual vapor pressure to the saturated vapor pressure.  Source:  http://glossary.ametsoc.org/wiki/Relative_humidity
  • Use of two or more fire pumps to move water a distance which would require excessive pressures in order to overcome friction loss if only one pump were employed at the source. 
Relay Tank
  • A tank, usually collapsible, used as a reservoir in the relay of water from one fire pump to another. 
Relief Valve
  • A pressure-controlled device which bypasses water at a fire pump to prevent excessive pressures when a nozzle is shut down. 
Reload Base
  • An airfield where airtankers are reloaded but not permanently stationed. 
Remote Automatic Weather Station (RAWS)
  • A weather station that transmits weather observations via GOES satellite to the Wildland Fire Management Information system. 
  • A radio signal station that automatically relays a radio transmission, sometimes over a different frequency, thereby increasing the range of transmission. Repeaters are often named for the mountaintops or peaks where they are installed. 
Report Time
  • Elapsed time from fire discovery until the first personnel charged with initiating action for fire suppression are notified of its existence and location. 
Reportable Fire
  • Any wildfire that requires fire suppression to protect natural resources or values associated with natural resources, or is destructive to natural resources. 
Reporting Locations
  • Location or facilities where incoming resources can check-in at the incident. Check-in locations include: incident command post (resources unit), incident base, camps, staging areas, helibases, helispots, and direct to the line. Check-in at one location only. 
Reporting Unit
  • The entity submitting a given incident report.
    • Definition Extension:  The entity must have a valid NWCG Unit Identifier (ID).
Request Number (Resource Order Number)
  • As resources are ordered to respond to an incident, Request Numbers (occasionally referred to as a resource order number) are issued. The order number includes the incident number, an alpha character (S = Supplies, E = Equipment, O = Overhead, A = Aircraft, C = Crews, M = Agency Provided Medical Care) followed by a sequential number.
Required Experience
  • Documented, satisfactory performance in a specified position needed to qualify for another (usually higher level) position. Required experience cannot be challenged. 
Required Training
  • A course or courses that must be completed prior to initiating a position task book. Training which has been identified as required cannot be challenged; an agency equivalent course may be used as a substitute when the course meets or exceeds a required course's learning and performance objectives. 
  • Saving a life from fire or accident; removing a victim from an untenable or unhealthy atmosphere. 
Rescue Medical
  • Any staffed ground vehicle capable of providing medical services. 
Rescue Medical Vehicle
  • Any staffed ground vehicle capable of providing emergency medical care and staffed with appropriate number of trained personnel and equipment for that incident. 
Residence Time
  • The time, in seconds, required for the flaming front of a fire to pass a stationary point at the surface of the fuel. The total length of time that the flaming front of the fire occupies one point. 
Residual Combustion Stage
  • The smoldering zone behind the zone of an advancing fire front. 
Residual Smoke
  • Smoke produced by smoldering material. The flux of smoke originating well after the active flaming combustion period with little or no vertical buoyancy and, therefore, most susceptible to subsidence inversions and down-valley flows. 
  • At a general level used to refer to the ability of a system (ecological or human) to resist damage and recover from a disturbance. In ecology, resiliency tends to refer to the ability of the system to return to the pre disturbance state with no assessment of whether that state is desirable or not. From a social perspective, resilience may reference ability to return to the original state but also can refer to the ability to recover to a state more likely to resist or recover quickly from future disturbance.
Resistance to Control
  • The relative difficulty of constructing and holding a control line as affected by resistance to line construction and by fire behavior. Also known as difficulty of control. 
Resistance to Line Construction
  • The relative difficulty of constructing control line as determined by the fuel, topography, and soil. 
Resource Capability
  • The ability of the wildland fire program to respond to current and anticipated workload needs for the area of concern. 
Resource Order
  • The form used by dispatchers, service personnel, and logistics coordinators to document the request, ordering or release of resources, and the tracking of those resources on an incident. 
Resource Ordering and Status System (ROSS)
  • A national system that provides automated support to interagency and agency dispatch and coordination offices. The system will provide current status of resources available to support all-risk activities; enable dispatch offices to exchange and track resource ordering information electronically; enable dispatch offices to rapidly and reliably exchange mission-critical emergency electronic messages. 
Resource Value-at-risk
  • Fire suppression planning tool providing a relative expression (in five classes) of fire effects on all resources (not the value of the resources themselves). 
  1. Personnel, equipment, services and supplies available, or potentially available, for assignment to incidents. Personnel and equipment are described by kind and type, e.g., ground, water, air, etc., and may be used in tactical, support or overhead capacities at an incident.
  2. The natural resources of an area, such as timber, grass, watershed values, recreation values, and wildlife habitat.
Resources Unit
  • Functional unit within the planning section responsible for recording the status of resources committed to the incident. The unit also evaluates resources currently committed to the incident, the impact that additional responding resources will have on the incident, and anticipated resource needs. 
  • A simple filter mask for individual protection against smoke and fumes, recommended for use in fire suppression on wildfires only; not recommended for use on structure fires or fires involving most hazardous materials. 
Responding Unit
  • Administrative entity that provides resources in response to the incident.
    • Definition Extension:  The entity must have a valid NWCG Unit Identifier (ID).
      • Not the type of resource responding.
      • Not limited to Jurisdictional or Protecting Units (contractors, volunteer fire departments, military resources, etc.)
Responsible Fire Agency
Restricted Airspace
  • Airspace of defined dimensions identified by an area on the surface of the earth within the flight of an aircraft, which is subject to restrictions (but not wholly prohibited). 
Restricted Category
  • Aircraft that is generally used for cargo, retardant dropping, agricultural operations, survey work and other specific projects, and may not transport passengers. 
  • Measures taken by jurisdictional agencies to impose bans and standards of use on certain human activities that could lead to the cause of wildland fire. Restrictions may be applied to: smoking in designated areas; open flame; mechanical operations in high-risk areas; and off-road use.
  • A substance or chemical agent which reduces the flammability of combustibles. 
Retardant Base
  • Ground facilities for mixing, storing, and loading fire retardant into airtankers. 
Retardant Coverage
  • Area of fuel covered and degree of coverage on the fuel by a fire retardant, usually expressed in terms of gallons per hundred square feet (liters per square meter). 
Retardant Drop
  • Fire retardant cascaded from an airtanker or helitanker. 
Return and Hold
  • An order to an airtanker pilot to return to the retardant base and await further instructions; mission completed, further loads not required. 
Reversible Siamese (SIMWYE)
  • Hose fitting that performs the functions of a Siamese or a wye (i.e., to combine the flow from two lines into a single line or to permit two lines to be taken from a single line).
Rheologic Properties
  • Flow characteristics of liquid fire retardants, especially their cohesiveness or ability to hold together while falling through the air. 
  • Science of deformation and flow of fire retardants and other liquids, especially of the cohesiveness bodies and stress-strain relationship of their particles. 
Rich Tool
  • A long-handled combination rake and cutting tool, the blade of which is constructed of a single row of mowing machine cutter teeth fastened to a piece of angle iron. Also known as a fire rake or council rake.
Right Angle Transect
Ring Fire
  • A fire started by igniting the full perimeter of the intended burn area so that the ensuing fire fronts converge toward the center of the burn. Set around the outer perimeter of a resource to establish a protective black-line-buffer. 
  1. The chance of fire starting as determined by the presence and activity of causative agents.
  2. A chance of suffering harm or loss.
  3. A causative agent.
  4. (NFDRS) A number related to the potential of firebrands to which a given area will be exposed during the rating day. 
Risk Assessment
Risk Index
  • A number related to the probability of a firebrand igniting a fire. 
Risk Management (RM)
  • A continuous, five-step process that provides a systematic method for identifying and managing the risks associated with any operation. 
Risk Source
  • Identifiable human activity that historically has been a major cause of wildfires on a protection unit; one of the eight general causes listed on the standard fire report. 
Risk Source Ratio
  • Portion of human-caused fires that have occurred on a protection unit chargeable to a specific risk source; calculated for each day of the week for each risk source. 
Rocker Lug Coupling
  • Hose coupling in which the lugs used for tightening or loosening are semicircular in shape and designed to pass over obstructions. 
Roll Cloud
  • A turbulent altocumulus-type cloud formation found in the lee of some large mountain barriers. The air in the cloud rotates around an axis parallel to the range. Also sometimes refers to part of the cloud base along the leading edge of a cumulonimbus cloud; it is formed by rolling action in the wind shear region between cool downdrafts within the cloud and warm updrafts outside the cloud. Also known as a rotor cloud.  Source:  http://glossary.ametsoc.org/wiki/Roll_cloud
  • Assembly of airfoils (rotor blades), together with a hub and attachments, that rotates about an axis to provide lift and/or thrust on a helicopter. 
Rotor Blast
  • Air turbulence occurring under and around the main rotor of an operating helicopter. Also known as a rotor downwash. 
Rotor Diameter
  • The main rotor arc in feet and inches (meters). Used for planning helispot clearance. 
  • The accumulation of living and dead ground and understory vegetation, especially grasses, forest litter, and draped dead needles, sometimes with addition of underbrush such as palmetto, gallberry, and wax myrtle. Most often used for southern pine types. 
Rough Reduction
  • Reduction of fire hazard in rough, usually by prescribed burning. 
Run (Of a Fire)
  • Rapid advance of the head of a fire, characterized by a marked transition in fireline intensity and rate of spread with respect to that noted before and after the advance. 
Running Fire
  • Behavior of a fire spreading rapidly with a well defined head. 
  • Any area wherein residences and other developments are scattered and intermingled with forest, range, or farm land and native vegetation or cultivated crops. 
Rural Fire District (RFD)
  • An organization established to provide fire protection to a designated geographic area outside of areas under municipal fire protection. Usually has some taxing authority and officials may be appointed or elected. 
Rural Fire Protection
  • Fire protection and firefighting problems that are outside of areas under municipal fire prevention and building regulations and that are usually remote from public water supplies. 
  • Depression or pass in a ridgeline. 
  • A form and process, used by wildland firefighting agencies, for reporting and resolving incidents relating to firefighter safety. The information collected is used to determine long-term trends and problem areas within the wildland fire industry. 
Safety Advisory
  • A safety alert addressing wildland fire safety information that isn't related to imminent or potential threats of injury. 
Safety Briefing
  • A safety briefing emphasizes key safety concerns on the incident and is presented at each briefing session. The safety briefing should contain information to alert incident personnel of potential risk/hazard considered to be most critical. 
Safety Circle
  • An obstruction-free circle around the (helicopter) landing pad. 
Safety Warning
  • A safety alert addressing wildland fire safety hazards that pose an imminent threat, or have potential to pose a threat, to life or property. 
Safety Zone
  • An area cleared of flammable materials used for escape in the event the line is outflanked or in case a spot fire causes fuels outside the control line to render the line unsafe. In firing operations, crews progress so as to maintain a safety zone close at hand allowing the fuels inside the control line to be consumed before going ahead. Safety zones may also be constructed as integral parts of fuel breaks; they are greatly enlarged areas which can be used with relative safety by firefighters and their equipment in the event of blowup in the vicinity. 
  • Dropping by an airtanker of its entire load of fire retardant at one time. 
Salvo Drop
  • Total retardant or water load dropped all at once. Usually done to knock down a hotspot. 
  • Part of a population; that portion of the population that is measured. 
Sample Size
  • The number of items or observations in a sample; usually denoted by lower case letter n. 
Sand Table Exercise (STEX)
  • A tactical decision game that employs a three-dimensional terrain model made from sand and various props to provide a visual representation of the situation described in the tactical decision game. 
Scope of Practice
  • The set of responsibilities and ethical considerations that define the extent or limits of the care provider within the current standards of practice. 
Scorch Height
  • Average heights of foliage browning or bole blackening caused by a fire. 
Scratch Line
  • An unfinished preliminary control line hastily established or constructed as an emergency measure to check the spread of fire. 
  • The process of agitating foam solution and air within a confined space (usually a hose) that produces tiny, uniform bubbles - the length and type of hose determine the amount of scrubbing and, therefore, foam quality. 
Sea Breeze
Sea-level Pressure
Season Code
  • One of four designations of seasonal plant development used in the 1988 version of NFDRS. 
Seasonal Monthly Average
  • Historically, the average number of human-caused fires occurring on a protection unit per month during the established fire season. 
Seasonal Risk Class
  • Objective ranking of protection units within an administrative group based on the number of human-caused fires for at least the past five years. 
Second Order Fire Effects (SOFE)
  • The secondary effects of fire such as tree regeneration, plant succession, and changes in site productivity. Although second order fire effects are dependent, in part, on first order fire effects, they also involve interaction with many other non-fire variables. 
  • Pilot who is designated to be second-in-command of an aircraft during flight time. 
Secondary Line
  • Any fireline constructed at a distance from the fire perimeter concurrently with or after a line already constructed on or near to the perimeter of the fire. Generally constructed as an insurance measure in case the fire escapes control by the primary line. 
Secondary Lookout
  • A lookout point intermittently used to supplement the visible area coverage of the primary lookout system when required by fire danger, poor visibility, or other factors.
  • The person who occupies such a station. 
Secondary Weather Station
  • Station at which minimum weather measurements are taken to compute ratings of burning conditions; provides supplementary information on weather experience. 
  • That organizational level with responsibility for a major functional area of the incident, such as operations, planning, logistics, finance/administration. The section is organizationally between branch and incident commander. 
  • A geographical area in which a task force/strike team leader or supervisor of a single resource is assigned authority and responsibility for the coordination of resources and implementation of planned tactics. A segment may be a portion of a division or an area inside or outside the perimeter of an incident. Segments are identified with Arabic numbers, i.e., A-1, etc. and are not to be used as radio designators. 
Self-Contained Breathing Apparatus (SCBA)
  • Portable air (not oxygen) tanks with regulators which allow firefighters to breathe while in toxic smoke conditions. Usually rated for 30 minutes of service. Used primarily on fires involving structures or hazardous materials. 
  1. Spacing of aircraft while landing and taking off at airports to achieve safe and orderly movement in flight.
  2. The horizontal and vertical spacing of aircraft working over or near a wildfire or other incident.
  3. Spacing of personnel while performing line construction activities. 
Serious Accident Investigation Team (SAIT)
  • A formal investigation team that is organized with the purpose of conducting an accident investigation for an occurred serious accident. The team is given full authorization to conduct the investigation from involved agencies through letter of delegation. 
Serious Aircraft Incident
  • An incident or malfunction that could adversely affect the safety of flight. 
Service Branch
  • A branch within the logistics section responsible for service activities at the incident. Includes the communications, medical and food units. 
  1. An individual incendiary fire.
  2. The point or points of origin of an incendiary fire.
  3. Material left to ignite an incendiary fire at a later time.
  4. Individual lightning or railroad fires, especially when several are started within a short time.
  5. Burning material at the points deliberately ignited for backfiring, slash burning, prescribed burning, and other purposes. 
Severity Funding
  • Suppression funds used to increase the level of presuppression capability and fire preparedness when predicted or actual burning conditions exceed those normally expected, due to severe weather conditions. 
Severity Index
  • A number that indicates the relative net effects of daily fire danger on the fire load for an area during a specified period, such as a fire season. 
Shaded Fuel Break
  • Fuel breaks built in timbered areas where the trees on the break are thinned and pruned to reduce the fire potential yet retain enough crown canopy to make a less favorable microclimate for surface fires. 
Shareable Content Object (SCO)
Shareable Content Object Re-usable Model (SCORM)
  • A specification for standardizing the reusability and interoperability of learning content. SCORM has been developed by the Advanced Distributed Learning initiative (ADL). SCORM focuses on two critical pieces of learning content interoperability:
    • It defines an aggregation model for packaging learning content.
    • ​It defines an API for enabling communications between learning content and the system that launches it. 
Shock Wave
  • The leading edge of an expanding air mass. 
Short Takeoff or Landing (STOL) Aircraft
  • An aircraft which has the capability of operating from a STOL runway in accordance with applicable airworthiness and operating regulations. 
Short Takeoff or Landing (STOL) Airstrip
  • Developed or undeveloped area that has been tested and will accommodate STOL aircraft. 
Short-Range Spotting
  • Firebrands, flaming sparks, or embers are carried by surface winds, starting new fires beyond the zone of direct ignition by the main fire. The range of such spotting is usually less than 1/4 mile. 
  • Persons or work for which employment is less than 12 months (excluding firefighters hired for a particular fire). 
Short-Term Fire Retardant
  • Fire retardant that inhibits combustion primarily by the cooling and smothering action of water. Chemicals may be added to the water to alter its viscosity or retard its evaporation, thereby increasing its effectiveness. 
Shoulder Carry
  • Method of carrying hose on the shoulders. 
  • A woody perennial plant differing from a perennial herb by its persistent and woody stem; and from a tree by its low stature and habit of branching from the base. 
Shrub Type
  • The two-category (evergreen, deciduous) classification of shrubs vegetation in the 1988 version of NFDRS. 
Shutoff Nozzle
  • Common type of fire hose nozzle permitting stream flow to be controlled by the firefighter at the nozzle rather than only at the source of supply. 
Shutoff Pressure
  • Maximum pressure a centrifugal pump will attain when water flow is clamped or shut off. 
  • Hose fitting (preferably gated) for combining flow from two or more lines of hose into a single stream; one male coupling to two female couplings. 
Significant Fire Event
  • An event measured by the occurrence of fire(s) that requires mobilization of additional resources from outside the fire event area. 
Significant Fire Potential
  • The likelihood a wildland fire event will require mobilization of additional resources from outside the area in which the fire situation originates. 
Significant Weather Trigger
  • A weather phenomenon resulting in an environment that has a significant impact on fire spread, intensity, or occurrence. Example: strong wind, unstable air mass, etc. 
Simms Bucket
  • Self-leveling helibucket slung under a helicopter which can be filled by hovering over a water source. 
Simple Hose Lay
  • A hose lay consisting of consecutively coupled lengths of hose without laterals. The lay is extended by inserting additional lengths of hose in the line between pumps and nozzle. Also known as single hose lay. 
  • An activity that imitates something real, but it's not real itself and it can be altered by users for the specific purpose of providing an experiential learning environment. Examples: Sand Table Exercise or CBT/WBT Forest Service Wildland Fire Simulation Scenario Editor. 
Single Arsonist
  • An offender who intentionally sets one fire. 
Single Door Drop
  • Technique whereby fire retardant is released from only one compartment of an airtanker. 
Single Resource
  • An individual, a piece of equipment and its personnel complement, or a crew or team of individuals with an identified work supervisor that can be used on an incident. 
Single Shift
  • Equipment is staffed with 1 operator or crew. A normal shift could be up to 16 hours long and may cross calendar days.
Single Stage Pump
  • Centrifugal pump with a single impeller. 
Site Preparation
  • Removal or killing of unwanted vegetation, residue, etc. by use of fire, herbicides, or mechanical treatment in preparation for reforestation and future management. 
Site Preparation Burning
  • Fire ignited to expose adequate mineral soil and control competing vegetation until seedlings of the desired species become established. 
Situation Analysis
  • Analysis of factors which influence suppression of an escaped fire from which a plan of attack will be developed; includes development of alternative strategies of fire suppression and net effect of each. 
Situation Awareness (SA)
  • An on-going process of gathering information by observation and by communication with others. This information is integrated to create an individual's perception of a given situation. 
Situation Unit
  • Functional unit within the planning section responsible for the collection, organization and analysis of incident status information, and for analysis of the situation as it progresses. Reports to the planning section chief. 
Situational Awareness (SA)
  • An on-going process of gathering information by observation and by communication with others. This information is integrated to create an individual's perception of a given situation.
Six Minutes for Safety (6MFS)
  • A daily safety briefing for wildland fire that focuses on high risk events found within a firefighter's scope of work that are performed on an infrequent basis. Also know as 6 Minutes for Safety.  View the Six Minutes for Safety website at https://www.nwcg.gov/committee/6mfs
Size Class of Fire
  • As to size of wildfire:
    • Class A - one-fourth acre or less;
    • Class B - more than one-fourth acre, but less than 10 acres;
    • Class C - 10 acres or more, but less than 100 acres;
    • Class D - 100 acres or more, but less than 300 acres;
    • Class E - 300 acres or more, but less than 1,000 acres;
    • Class F - 1,000 acres or more, but less than 5,000 acres;
    • Class G - 5,000 acres or more.
  • The evaluation of the fire to determine a course of action for suppression. 
Skid Hose Load
  • Load of hose specially arranged on top of a standard hose load to permit dropping the working line at the fire. 
Skid Trail
  • Any road or trail formed by the process of skidding logs from stump to landing. 
Skidder Unit
  • A self-contained unit consisting of a water tank, fire pump, and hose specially designed to be carried on a logging skidder for use in forest fire suppression. 
  • Any aircraft equipped to pick up water while moving on or over water. 
Sky Cover
  • Debris resulting from such natural events as wind, fire, or snow breakage; or such human activities as road construction, logging, pruning, thinning, or brush cutting. It includes logs, chunks, bark, branches, stumps, and broken understory trees or brush. 
Slash Disposal
  • Treatment of slash to reduce fire hazard or for other purposes. Preferred to "Brush Disposal." 
  • A net attached by a lanyard to a helicopter cargo hook and used to haul supplies. 
Sling Load
  • Any cargo carried beneath a helicopter and attached by a lead line and swivel. 
Sling Psychrometer
Slip-on Tanker
  • A tank, a live hose reel or tray, an auxiliary pump, and an engine combined into a single one-piece assembly which can be slipped onto a truck bed or trailer. 
Slope Class
  • One of five categories used to describe the topography of a fire danger rating area. 
Slope Percent
  • The ratio between the amount of vertical rise of a slope and horizontal distance as expressed in a percent. One hundred feet of rise to 100 feet of horizontal distance equals 100 percent. 
Slope Winds
  • A fire edge that crosses a control line or natural barrier intended to confine the fire. 
    • synonym: Breakover
Slug Flow
  • The discharge of distinct pockets of water and air due to the insufficient mixing of foam concentrate, water, and air in a compressed air foam system. 
Small Aircraft
  • An aircraft of 12,500 pounds (5,669 kg) or less, maximum certificated takeoff weight. 
  • Small particles of carbon, tarry and water vapor resulting from the incomplete combustion of carbonaceous materials such as wood, coal or oil. 
Smoke Concentration
  • The amount of combustion products found in a specified volume of air, commonly expressed as micrograms of emission per cubic meter of air. 
Smoke Intrusion
  • Smoke from prescribed fire entering a designated area at unacceptable levels. 
Smoke Management
  • The policies and practices implemented by air and natural resource managers directed at minimizing the amount of smoke entering populated areas or impacting sensitive sites, avoiding significant deterioration of air quality and violations of National Ambient Air Quality Standards, and mitigating human-caused visibility impacts in Class I areas. 
Smoke Pall
  • Extensive, thick blanket of smoke spreading more or less horizontally from a fire. 
Smoke Plume
Smoke Sensitive Area (SSA)
  • Area in which smoke from outside sources is intolerable, for reasons such as heavy population, existing air pollution, or intensive recreation or tourist use. 
Smoke Target
  • An area that may be adversely affected by smoke from a prescribed burn. Also known as a smoke sensitive area. 
Smoke Vent Height
  • Level, in the vicinity of the fire, at which the smoke ceases to rise and moves horizontally with the wind at that level. 
Smoke-Induced Fog (SIF)
  • A dense fog (water droplets suspended in the atmosphere) that forms away from a fire site when surface smoke comprised of increased fine particulates and water vapor, combines with ambient air that is already prone to natural fog formation.
    • Definition Extension: Under these conditions, smoke serves as a catalyst and induces surface fog formation, reducing visibility to a greater extent than smoke or fog individually. Smoke can induce fog in two ways.
      1. Surface smoke contains additional water which is a byproduct of combustion. This excess water can induce fog or if present increase the density of existing fog.
      2. Smoke contains particulate matter which may serve as condensation nuclei thus increasing the number of smaller fog droplets in smoke.
      In either case, SIF reduces visibility beyond that of the separate individual impacts of smoke or fog. SIF can occur anywhere within surface smoke plume but will usually be found in low-lying areas and drainages where ambient conditions most likely favor fog formation. Fog has formed when observed relative humidity is under 100% and thus, it forms more easily in the presence of smoke. SIF is also most likely to be found late at night or early in the morning when ambient conditions most likely favor fog formation.
Smokey Bear
  • The symbol of the Cooperative Forest Fire Prevention Program since 1945. Smokey's image is protected by US Federal Law and is administered by the USDA Forest Service, the National Association of State Foresters and the Ad Council. 
Smoking (As a Fire Cause)
  • Wildfires caused by smokers from matches, lighters, tobacco, or other smoking material. 
Smoldering Combustion
  • Combined processes of dehydration, pyrolysis, solid oxidation, and scattered flaming combustion and glowing combustion, which occur after the flaming combustion phase of a fire; often characterized by large amounts of smoke consisting mainly of tars. 
Smoldering Combustion Phase
  • Phase of combustion immediately following flaming combustion. Emissions are at twice that of the flaming combustion phase. 
  • A standing dead tree or part of a dead tree from which at least the leaves and smaller branches have fallen. Often known as a stub, if less than 20 feet tall. 
Snorkel Tank
  • A fixed tank attached to the belly of the helicopter that has a pump-driven snorkel attached. The helicopter hovers over the water source with the end of the snorkel immersed, the pump then fills the tank. 
Soft Suction
  • Commonly accepted term for short length of large diameter soft hose used to connect a structural or wildland engine with a hydrant. No vacuum is involved because the hose is useful only when the engine receives water at a rate of flow in excess of the demand of the pump. 
Solar Radiation
  • The amount of sunlight exposed to the fuels. 
  • Carbon dust formed by incomplete combustion. 
  • Single round trip made by an airtanker from a tanker base to a fire and return. 
Sound Warbler
  • A signaling device mounted on retardant aircraft which generates a tremulous siren sound to warn firefighters on the ground that a plane is approaching to drop retardant. 
Sounding (Upper Air Sounding)
  • A sampling of upper air conditions made by means of instruments and a small radio transmitter on a free balloon. Automatic radio signals originated by action of weather instruments are sent to a ground receiver. These signals are interpreted for use in analyzing and predicting upper air conditions over a wide area of the earth. Weather elements determined at a number of altitude points as the balloon rises are temperature, atmospheric moisture, pressure, wind direction and speed. Similar soundings may be made using fixed balloons or tethersondes.  Source:  http://glossary.ametsoc.org/wiki/Upper-air_sounding
  • A point, line, or area, at which mass or energy is added to a system, either instantaneously or continuously. Examples of sources in the context of air pollution are as follows: a smoke stack is a point source; a freeway is a line source; field or slash burning are area sources. 
  • Chipping or pitting of concrete, masonry, or stone surfaces. 
  • Distance equal to the wingspread of the airtanker being used; used for corrections right or left of the flight path. 
Span of Control
  • The supervisory ratio of from three-to-seven individuals, with five-to-one being established as optimum. 
  • Metal wrench used to tighten and free hose connections. 
Spark Arrester
  • A device installed in a chimney, flue, or exhaust pipe to stop the emission of sparks and burning fragments. 
Special Interest Group (SIG)
  • In WIMS, a group of weather stations. 
Special Visual Flight Rules (VFR)
  • Aircraft operating in accordance with clearances within control zones in weather conditions less than the basic Visual Flight Rules weather minima. 
Specific Heat
  • The heat required to raise a unit mass of a substance one degree kelvin. It is the heat capacity of a system per unit mass; i.e., the ratio of the heat absorbed (or released) to the corresponding temperature rise (or fall). 
Specific Origin Area (SOA)
  • The smaller area within the general origin area where the fire's direction of spread was first influenced by fuel, weather, and/or topography. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
    • Definition Extension: The SOA will contain the Ignition Area. Generally this area is characterized by subtle and microscale fire pattern indicators as a result of less intense burning associated with the initial stages of the fire.
  • Standby crew in an area of expected high fire occurrence, generally on a day of critical fire weather. 
Split Drop
  • Retardant drop made from one compartment at a time from an airtanker with a multi-compartment tank. 
Split Flow
  • A divergent wind field. Storms moving into a split field tend to lose strength. Winds are generally light in such a flow field. 
Spontaneous Combustion
  • Combustion of a thermally isolated material initiated by an internal chemical or biological reaction producing enough heat to cause ignition. 
Spot Burning
  • A modified form of broadcast slash burning in which the greater accumulations of slash are fired and the fire is confined to these spots. Sometimes known as "Jackpot Burning" or "Jackpotting."
Spot Change
  • The second continuous day of an incident, a regular government employee's normal daily tour of duty is "spot changed" to where the first 8, 9, or 10 hours worked are base hours.
Spot Fire
  • Fire ignited outside the perimeter of the main fire by a firebrand. 
Spot Fire Technique
  • A method of lighting prescribed fires where ignition points are set individually at a predetermined spacing and with predetermined timing throughout the area to be burned. 
Spot Weather Forecast
  • A special forecast issued to fit the time, topography, and weather of a specific incident. These forecasts are issued upon request of the user agency and are more detailed, timely, and specific than zone forecasts. Usually, on-site weather observations or a close, representative observation is required for a forecast to be issued. 
  • In smokejumping, rappelling, and paracargo operations, the individual responsible for selecting drop target and supervising all aspects of dropping smokejumpers, rappellers, or cargo. 
  • Behavior of a fire producing sparks or embers that are carried by the wind and which start new fires beyond the zone of direct ignition by the main fire. 
  • Water applied through an orifice in finely divided particles to absorb heat and smother fire, to protect exposures from radiated heat, and to carry water toward otherwise inaccessible fire. 
Spread Component
  • Part of the National Fire Danger Rating System (NFDRS). A rating of the forward rate of spread of the head of a fire. 
Spread Index
  • A number used to indicate relative (not actual) rate of spread. 
Spread Index Meter
  • Device for combining measured ratings of various fire danger factors into numerical classes or rates of spread. 
Spur Ridge
  • A small ridge which extends finger-like from a main ridge. 
Squall Line
  • Any nonfrontal line or narrow band of active thunderstorms extending across the horizon. It is of importance to fire behavior due to accompanying strong gusty winds and the possibility of such a line passing between regular weather observation stations without being reported. Also known as line squall.  Source:  http://glossary.ametsoc.org/wiki/Squall_line
Stable Atmosphere
  • Condition of the atmosphere in which the temperature decrease with increasing altitude is less than the dry adiabatic lapse rate. In this condition, the atmosphere tends to suppress large-scale vertical motion. Also known as stable air. 
Stable Layer of Air
  • A layer of air having a temperature change (lapse rate) of less than dry adiabatic (approximately -5.4 degrees F per 1,000 feet) thereby retarding either upward or downward mixing of smoke. 
  • Aircraft orbiting the rendezvous area; usually refers to vertical deployment at 500-foot (150 m) altitudinal separation between aircraft. 
Staff Ride
  • A case study of a previous incident that is conducted on the actual physical site where the incident occurred. A staff ride is an experiential learning method that involves three distinct parts: a preliminary study, a site visit, and a post-visit integration session. 
Staffing Index
  • A NFDRS component, index or related indicator (ignition component, spread component, energy release component, burning index, Keetch-Byram drought index) whose outputs are correlated to the local fire problem, used to determine staffing levels. 
Staffing Level
  • The basis for decision support for daily staffing of initial attack resources and other activities. A level of readiness and an indicator or daily preparedness. 
Staging Area
  • Locations set up at an incident where resources can be placed while awaiting a tactical assignment on a three (3) minute available basis. Staging Areas are managed by the Operations Section. 
Stagnant Conditions
  • Atmospheric conditions under which pollutants build up faster than the atmosphere can disperse them. 
Stand Replacing Fire
  • Fire which kills all or most of the living overstory trees in a forest and initiates forest succession or regrowth. Also explicitly describes the nature of fire in grasslands and some shrublands. 
Stand-By Crew
  • A group of trained firefighters stationed at a dispatch point for quick, rapid deployment. 
Standard Coupling
  • Fire hose coupling with American National Standard (NH) threads. 
Standard Drying Day
  • Part of the National Fire Danger Rating System (NFDRS). Day which produces the same net drying as experienced during a 24-hour period under laboratory conditions in which dry-bulb temperature is maintained at 80º F and relative humidity is maintained at and relative humidity is maintained at 20%. 
Standard Hydrologic Exchange Format code (SHEF)
  • A two-character code to describe each measurement taken at a weather station. 
Standard Operating Procedure (SOP)
  • Specific instructions clearly spelling out what is expected of an individual every time they perform a given task. A standard operating procedure can be used as a performance standard for tasks that are routinely done in the operational environment. 
Standard Operational Procedure (SOP)
  • Specific instructions clearly spelling out what is expected of an individual every time they perform a given task. A standard operational procedure can be used as a performance standard for tasks that are routinely done in the operational environment. 
Standards, Incident Position
  • Incident Position standards are a component of NWCG standards. They enable consistent and uniform performance by personnel mobilized by position under NIMS-ICS principles. Incident position standards include incident position descriptions (duties and responsibilities) and position qualification requirements for training, experience, physical fitness, and position currency.
Standards, NWCG
  • NWCG standards establish common practices and requirements that enable efficient and coordinated national interagency wildland fire operations. These standards may include guidelines, procedures, processes, best practices, specifications, techniques, and methods. NWCG standards are interagency by design; however, the decision to adopt and utilize them is made independently by the individual member agencies and communicated through their respective directives systems.
State of Weather
  • A code which expresses the amount of cloud cover, kind of precipitation, and/or restrictions to visibility being observed at the fire danger station at basic observation time. 
Static Pressure
  • Water pressure head available at a specific location when no water is being used so that no friction loss is being encountered. Static pressure is that pressure observed on the engine inlet gauge before any water is taken from the hydrant. 
Static Water Supply
  • Supply of water at rest which does not provide a pressure head for fire suppression but which may be employed as a suction source for fire pumps (e.g., water in a reservoir, pond, or cistern). 
Station Catalog
  • A WIMS file that contains all the information defined for a weather station. 
Station ID
  • A six-digit number assigned to a specific weather station by the servicing National Weather Service Fire Weather Office. 
Station Pressure
  • The number that results from manipulating raw data according to a specified procedure; associated with samples. 
Statistical Fire
  • In general, an actionable fire, on which any fire agency reports and maintains specified information (e.g., cause, date and point of origin, size, fire damage). 
  • A branch of mathematics dealing with the collection, analysis, and interpretation of numerical data. 
Step Test
  • Five-minute test used to predict a person's ability to take in, transport, and use oxygen (aerobic capacity), the most important factor limiting the ability to perform arduous work. 
Storm Center
  • The central point or area of a weather system associated with increased winds, clouds or precipitation (or any combination thereof). 
Straight Stream
  • Water or fire retardant projected directly from the nozzle (as contrasted with a fog or spray cone), provided by a solid stream orifice or by adjusting a fog jet into a straight stream pattern. 
Straight Stream Nozzle
  • A hose tip spout designed to provide the maximum reach of water without feathering. 
  • A wire or metal guard used to keep debris from clogging pipe or other openings made for removing water; used in pumps and on suction hose to keep foreign material from clogging or damaging pumps. 
Strategic Objective
  • A broad statement, specified in a land/resource management or fire management plan that identifies change in water, soil, air, or vegetation from the present to proposed conditions, or describes an existing resource condition that should be maintained. Strategic objectives deal with large areas over long time periods and project intended outcomes of management activities that contribute to the maintenance or achievement of desired conditions. 
  • The general plan or direction selected to accomplish incident objectives. 
Strike Team
  • Specified combinations of the same kind and type of resources, with common communications, and a leader. 
  • A narrow finger or band of fuel that connects two or more patches or areas of wildland fuel. 
Strip Burning
  1. Burning by means of strip firing.
  2. In hazard reduction, burning narrow strips of fuel and leaving the rest of the area untreated by fire. 
Strip Firing
  • Setting fire to more than one strip of fuel and providing for the strips to burn together. Frequently done in burning out against a wind where inner strips are fired first to create drafts which pull flames and sparks away from the control line. 
Strip-Head Fire
  • A series of lines of fire ignited near and up wind (or downslope) of a firebreak or backing fire so they burn with the wind (or upslope) toward the firebreak or backing fire. 
Structural Fire Protection
  • The protection of homes or other structures from an active wildland fire.
  • A constructed object, usually a free-standing building above ground. 
Structure (Vegetative)
  • The arrangement of vegetation in terms of density, basal area, cover, and vertical arrangement. 
Structure Fire
  • Fire originating in and burning any part or all of any building, shelter, or other structure. 
Structure Protection Plan
  • A plan developed by the Structure Protection Specialist that provides operational guidelines to suppression resources responsible for providing wildland fire structure protection. 
  • Downward or sinking motion of air in the atmosphere. Subsiding air warms due to compression. Increasing temperature and decreasing humidities are present in subsiding air. Subsidence results in a stable atmosphere inhibiting dispersion. Subsidence is generally associated with high atmospheric pressure. 
Subsidence Inversion
  • An inversion caused by subsiding air, often resulting in decreased atmospheric mixing conditions. 
  • The process of vegetational development whereby an area becomes successively occupied by different plant communities of higher ecological order. 
Suction Lift
  • In fire service, the number of feet (meters) of vertical lift from the surface of the water to the center of the pump impeller. In testing, e.g., fire department pumpers are required to discharge their rated capacity at 150 pounds (1034 kPa) net pump pressure at a 10-foot (3 meter) lift. The suction gauge would indicate the vertical suction lift in inches of mercury when the pump was primed with no appreciable water flowing. 
  • The adjective classification of the sky when 5/10 or less of the sky is obscured by clouds. Part of the National Fire Danger Rating System (NFDRS). 
Sunset and Sunrise
  • The mean solar times of sunset and sunrise as published in the Nautical Almanac, converted to local standard time for the locality concerned. 
Superficial Burn
  • A minor thermal burn involving the outer layer of skin, i.e. "a sunburn". It is characterized by reddening of the skin and perhaps some swelling without blisters. Also known as First Degree Burn.
  • An extremely dense surface fog (water droplets suspended in the atmosphere) at the site of combustion that reduces visibility to less than three meters (ten feet).
    • Definition Extension: Superfog forms at the site of combustion when warm humid smoke from smoldering combustion mixes with cold humid air. It is sometimes referred to as “whiteout events”. Superfog is the most severe case of smoke-induced fog. Superfog may last for a few seconds to a few hours depending of the dryness of the ambient air. Thus, superfog may not last more than a few meters (feet) beyond the site of combustion or, under certain wind conditions, it may be carried several kilometers (miles). Superfog presence is most likely late at night or early in the morning in low-lying basins or drainages when/where ambient conditions favor fog persistence.
  • The ICS title for individuals responsible for command of a division or group. 
Supplemental Fire Department Resources
  • Overhead tied to a local fire department, generally by agreement, who are mobilized primarily for response to incidents or wildland fires outside their district or mutual aid zone. Supplemental fire department resources are not a permanent part of the local fire organization and are not required to attend scheduled training, meetings, etc. of the department staff. 
  • Minor items of equipment and all expendable items assigned to an incident. 
Supply Unit
  • Functional unit within the support branch of the logistics section responsible for ordering equipment and supplies required for incident operations. 
Support Branch
  • A branch within the logistics section responsible for providing personnel, equipment and supplies to support incident operations. Includes the supply, facilities and ground support units. 
Support Costs
  • On-incident costs and off-incident costs. On-incident costs include caterer, shower units, mobile commissary, cache supplies, and materials, etc. Off-incident costs include expanded dispatch, buying teams, administrative payment teams, cache personnel, area command, transportation to/from incident, etc. 
Support Resources
  • Non-tactical resources under the supervision of the logistics, planning, finance/administration sections or the command staff. 
Supporting Agency
Supporting Technologies
  • Any technology which may be used to support NIIMS. Examples of these technologies include GIS mapping, infrared technology, NFDRS, communications, dispatch coordination, and national cache system. 
  • An agent that extinguishes the flaming and glowing phases of combustion by direct application to the burning fuel. 
Suppression Crew
  • Two or more firefighters stationed at a strategic location for initial action on fires. Duties are essentially the same as those of individual firefighters. 
Surface Area-to-Volume Ratio
  • The ratio between the surface area of an object, such as a fuel particle, to its volume. The smaller the particle, the more quickly it can become wet, dry out, or become heated to combustion temperature during a fire. 
Surface Fire
  • Fire that burns loose debris on the surface, which includes dead branches, leaves, and low vegetation. 
Surface Fuel
  • Fuels lying on or near the surface of the ground, consisting of leaf and needle litter, dead branch material, downed logs, bark, tree cones, and low stature living plants. 
Surface High
  • An area on the earth's surface where atmospheric pressure is at a relative maximum. Winds blow clockwise around highs in the Northern Hemisphere but, due to friction with the earth's face, tend to cross constant pressure lines away from the high center. Air is usually subsiding above a surface high. This causes warming due to air compression. This results in stable atmospheric conditions and light surface winds. 
Surface Low
  • An area on the earth's surface where atmospheric pressure is at a relative minimum. Winds blow counter-clockwise around lows in the Northern Hemisphere but, due to friction with the earth's surface, tend to cross constant pressure lines toward the low center. Upon converging into the low's center, air currents are forced to rise. As air rises it cools due to expansion. Cooling reduces its capacity to hold moisture; so cloudiness and precipitation are common in lows. If a low center intensifies sufficiently it will take on the characteristics of a storm center with precipitation and strong winds.
Surface Tension
  • The elastic-like force at the surface of a liquid, tending to minimize the surface area and causing drops to form. Expressed as Newtons per meter or dynes per centimeter (1 Newton/m=1,000 dynes/cm). 
Surface Wind
  • Wind measured at a surface observing station, customarily at some distance (usually 20 feet) above the average vegetative surface to minimize the distorting effects of local obstacles and terrain. 
  • A surface active agent; any wetting agent. A formulation which, when added to water in proper amounts, will materially reduce the surface tension of the water and increase penetration and spreading abilities of the water. 
  • Rapid increase in water flow which may result in a corresponding pressure rise. 
Surplus Property
  • Any excess personal property not required for the needs and the discharge of the responsibilities of all federal agencies as determined by the General Services Administration (GSA). 
Survival Zone
  • A natural or cleared area of sufficient size and location to protect fire personnel from known hazards while inside a fire shelter. Examples include rock slides, road beds, clearings, knobs, wide ridges, benches, dozer lines, wet areas, cleared areas in light fuels, and previously burned areas. These are all areas where you expect no flame contact or prolonged heat and smoke. 
Suspended Fuel
  • A wildland fuel that is suspended off the ground in such a way that fire may burn both over and under it. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.
    • Definition Extension: Heated air and fire moving under the suspended fuel wraps around the backside due to wind vortex flame wrap creating a fire pattern indicator the opposite of a typical protection fire pattern indicator.
  1. A worker who assists fallers and/or sawyers by clearing away brush, limbs and small trees. Carries fuel, oil and tools and watches for dangerous situations.
  2. A worker on a dozer crew who pulls winch line, helps maintain equipment, etc., to speed suppression work on a fire. 
  • Act of clearing brush and other material from around the base of trees and where trees are to be bucked, prior to falling or bucking, as protection against saw kickback and to provide safe footing. 
  • An accessory used between the helicopter cargo hook and sling load to allow free turning of the load. 
  • Literally, at one time. Thus, in meteorological usage, the weather conditions over a large area at a given point in time. 
Synoptic Chart
  • In meteorology, any chart or map on which data and analyses are presented that describe the state of the atmosphere over a large area at a given moment in time. 
Systematic Methodology
  • Cards filled out with essential information for each resource they represent. The cards are color-coded to represent different types of resources. 
Tactical Decision Game (TDGS)
  • A simple role-play simulation technique that challenges participants to make decisions and communicate those decisions to others. A tactical decision game is an experiential learning method that is tactical in nature and has time and information constraints to put participants under some level of stress.
Tactical Direction
  • Direction given by the operations section chief which includes the tactics appropriate for the selected strategy, the selection and assignment of resources, tactics implementation, and performance monitoring for each operational period. 
  • Deploying and directing resources on an incident to accomplish the objectives designated by strategy. 
  • Connecting a (airtanker) drop to the forward part of a previous drop. 
Tail Rotor
  • A small rotor, mounted on the tail of a conventional helicopter, which counteracts torque of the main rotor and provides a measure of directional control. 
Tailgate Safety Session
  • Brief meetings held at the beginning, during, or end of an operational period to discuss new work assignments, new work methods, changes in plans, use of tools and equipment, and recognition and protection against work hazards that may be encountered. 
  • Two or more units of any one type working one in front of the other to accomplish a specific fire suppression job; the term can be used in connection with crews of firefighters, power pumps, bulldozers, etc. 
Tank and Gating System
  • Tanks, doors, and release mechanism installed in aircraft for cascading fire retardants. 
Tank Trailer
  • Specialized trailer on which is mounted a tank, fire pump, hose, and ancillary equipment. 
  • Specific portion of the fire on which fire retardant or water is to be dropped by airtankers or helitankers.
Target Hazard
  • Facilities in which there is great likelihood of loss of life or property. 
  • A unit of work activity that is a logical and necessary action in the performance of a behavior; how the behavior is demonstrated or performed in a particular context. 
Task Force
  • Any combination of single resources assembled for a particular tactical need, with common communications and a leader. A task force may be pre-established and sent to an incident, or formed at an incident. 
Temperature Coefficient
  • The relative change of some measurable quantity with change of temperature, like burning time per unit length, mostly expressed as mean change per degree in percentage of mean temperature within a certain range. 
Ten-hour Timelag Fuel Moisture (10-h TL FM)
  • The moisture content of the l0-hour timelag roundwood fuels. 
Ten-hour Timelag Fuels
  • Dead fuels consisting of roundwood 1/4 to l-inch (0.6 to 2.5 cm) in diameter and, very roughly, the layer of litter extending from immediately below the surface to 3/4 inch (1.9 cm) below the surface. 
Terra Torch ®
  • Device for throwing a stream of flaming liquid, used to facilitate rapid ignition during burn out operations on a wild fire or during a prescribed fire operation. 
Test Fire
  • A prescribed fire set to evaluate such things as fire behavior, fire effects, detection performance, or control measures. 
Thermal Belt
  • An area of mountainous slope (characteristically the middle third), where the top of the radiation inversion intersects the slope. It typically experiences the least variation in diurnal temperatures and has the highest average temperatures and, thus, the lowest relative humidity. Its presence is most evident during clear weather with light wind. 
Thermal Imagery
  • The display or printout of an infrared scanner operating over a fire. Also known as infrared imagery. 
Thin Layer
  • Layer of clouds whose ratio of dense sky cover to total sky cover is 1/2 or less. 
Thin Sky Cover
  • Sky cover through which higher clouds or the sky can be detected. 
Third-Party Case
  • An injury or illness/disease caused by a person or object under circumstances that indicate there may be a legal liability on a party other than the federal or state government. Contact the home unit for case management advice.
  • An incident likely to cause damage or danger to protected lands.
    • Business Rule:  Responding organization determines threat to protected lands.
Threat Fire
  • Any uncontrolled fire near to or heading toward an area under organized fire protection. 
  • Localized storm characterized by one or more electrical discharge(s). 
  • Act of connecting a control line to another fireline or an intended firebreak. 
Time Delay Device
  • A device employed to allow a firesetter the opportunity to leave the scene prior to the ignition of the fire. 
Time in Service
  • With respect to maintenance time records, the time from the moment an aircraft leaves the surface of the earth until it touches at the next point of landing. 
Time Recording
  • Recording all time presented by others. Personnel time recorders record time from the Crew Time Report, SF-261, to the Incident Time Report, OF-288. Equipment time recorders record time from the Emergency Equipment Shift Ticket, OF-297, to the Emergency Equipment Use Invoice, OF-286.
Time Unit
  • Functional unit within the Finance/Administration Section responsible for recording personnel time and managing the commissary. 
Time-Temperature Curve
  • Graph showing the increase in temperature at a specified point in a fire as a function of time, beginning with ignition and ending with burnout. 
  • Tracking on-shift time of incident resources. Timekeeping is accomplished on the Crew Time Report, SF-261, or the Emergency Equipment Shift Ticket, OF-297.
Timelag (TL)
  • Time needed under specified conditions for a fuel particle to lose about 63 percent of the difference between its initial moisture content and its equilibrium moisture content. If conditions remain unchanged, a fuel will reach 95 percent of its equilibrium moisture content after 4 timelag periods. 
  • Burnable organic material (duff, peat, rotten wood, etc.) with a high surface to volume ratio. 
  • Nozzle tips used to change orifice size of a hose stream. 
  1. Ignition and subsequent envelopment in flames, usually from bottom to top, of a tree or small group of trees.
  2. To set fire to property deliberately and maliciously.
  3. A professional firesetter-for-hire. 
  • The burning of the foliage of a single tree or a small group of trees, from the bottom up. 
Total Fuel
  • All plant material both living and dead that can burn in a worst case situation. 
Total Mobility
  • The capability to move, position, and utilize established forces to meet existing and anticipated fire protection needs nationwide. 
Total Risk
  • Part of the National Fire Danger Rating System (NFDRS). Sum of lightning and human-caused risk values; cannot exceed a value of 100. 
Total Suspended Particulate Matter (TSP)
  • Particles emitted from a pollution source regardless of size. Federal and state ambient and emission standards exist for TSP. 
Touchdown Pad
  • That portion of a heliport or helispot where the helicopter lands. 
  • The hours of a day (a daily tour-of-duty) and the days of an administrative workweek (a weekly tour-of-duty) that constitutes an employee's regularly scheduled administrative workweek.
  • Relating to a harmful effect by a poisonous substance on the human body by physical contact, ingestion, or inhalation. 
Toxic Substance
  • A chemical or mixture that may present an unreasonable risk of injury to health or the environment. 
  • A rubber tired or tracked rider-controlled automotive vehicle, used in wildland fire management for pulling a disk or a plow to construct fireline by exposing mineral soil. 
Tractor Plow
  • A steel tracked vehicle with or without a front mounted blade equipped with a plow for exposing mineral soil. Sometimes a tractor plow with a front mounted blade is referred to as a dozer plow.
Traffic Pattern
  • Traffic flow that is prescribed for aircraft landing at, taxiing on, and taking off from, an airport. Usual components of a traffic pattern are upwind leg, crosswind leg, downwind leg, base leg, and final approach. 
Trail Drop
  • An unbroken line of retardant used for constructing a retardant line. 
  • Combustible material, such as rolled rag, blankets and newspapers, or flammable liquid, used to spread fire from one area to others; usually used in conjunction with an incendiary device. 
  • An individual who has met all required training and position experience for a specified position and is approved by their home unit's certifying official, to initiate a performance based training assignment in order to become qualified in the position. 
  • A position-qualified individual who provides instruction to a trainee in the classroom, on-the-job, or on an incident. While many of the requirements of the trainer/coach are similar to the evaluator, it is important that the roles of training and evaluation remain separate. 
Transfer of Command
  • The ICS management process in which the on-scene incident commander at a specified time hands off command responsibilities to the incident commander that will be taking over incident command. 
  • In the 1978 version of NFDRS, the herbaceous stage when herbaceous fuel moisture is between 120% and 30%. 
Transition Zone
  • Area of change between advancing, lateral, and backing vectors.
Translational Lift
  • Lift that is gained when a helicopter translates from a hover into forward flight; additional lift increases with increasing airspeed and is derived by the rotor system moving into undisturbed air. 
Transport Wind Speed
  • A measure of the average rate of the horizontal transport of air within the Mixing Layer. May also be the wind speed at the final height of plume rise. Generally refers to the rate at which emissions will be transported from one area to another. 
Transportation Map
  • Base map of the planning unit showing all roads, trails, heliports, and airfields existing and programmed for construction. 
Travel Time
  • Compensable time en route to or from an emergency incident. 
  • A small ditch often constructed below a fire on sloping ground (undercut or underslung line) to catch rolling material. 
  • An elongated area of relatively low atmospheric pressure, usually extending from the center of a low pressure system. 
True Airspeed
  • Velocity of an aircraft in its flight path relative to the air through which it is moving. 
True Bearing
  • Bearing by true north rather than magnetic north. 
  • Irregular motion of the atmosphere usually produced when air flows over a comparatively uneven surface such as the surface of the earth; or when two currents of air flow past or over each other in different directions or at different speeds. 
Turn the Corner
  • Contain a fire along a flank of the fire and begin containing it across the head. Refers to ground or air attack. 
Turnaround Time
  • Time used by an airtanker or helitanker to reload and return to the fire. 
Turnout Coat
  • A coat with a fire resistant outer shell and a thermal and moisture barrier liner. Used primarily by structure firefighters. Also known as a fire coat. 
Two-Way Radio
  • Radio equipment with transmitters in mobile units on the same frequency as the base station, permitting conversation in two directions using the same frequency in turn. 
  • Refers to resource capability. A Type 1 resource provides a greater overall capability due to power, size, capacity, etc., than would be found in a Type 2 resource. Resource typing provides managers with additional information in selecting the best resource for the task. 
Ultra High Frequency (UHF-FM)
  • Radio frequencies from 300 Megahertz (MHz) to 3,000 MHz with a normal range of less than 50 miles. Radio frequency common to military aircraft and used in the logistics radio system. The most common frequencies used by fire and public safety are from 406 MHz to 512 MHz. 
Unacceptable Risk
  • Level of risk as determined by the risk management process which cannot be mitigated to an acceptable safe level. 
Uncontrolled Airport
  • Airport not having an approved agency with radio communications to direct aircraft take-offs and landings. 
Uncontrolled Fire
  • Any fire which threatens to destroy life, property, or natural resources, and (a) is not burning within the confines of firebreaks, or (b) is burning with such intensity that it could not be readily extinguished with ordinary tools commonly available. 
  • A fire that consume surface fuels but not the overstory canopy.
Undercut Line
  • A fireline below a fire on a slope. Should be trenched to catch rolling material. Also called underslung line.
Understory Burning
  • Prescribed burning under a forest canopy.
Unified Area Command
  • A unified area command is established when incidents under an area command are multijurisdictional. 
Unified Command
  • In ICS, unified command is a unified team effort which allows all agencies with jurisdictional responsibility for the incident, either geographical or functional, to manage an incident by establishing a common set of incident objectives and strategies. This is accomplished without losing or abdicating authority, responsibility, or accountability. 
Unified Ordering Point (UOP)
  • Single location through which all incident resource orders are processed.
  1. The organizational element having responsibility within a functional area in the incident command structure such as operations, planning, logistics or finance.
  2. A generic term that represents an organizational entity that only has meaning when it is contextualized by a descriptor, e.g. jurisdictional.
    • Definition Extension:  When referring to an organizational entity, a unit refers to the smallest area or lowest level.  Higher levels of an organization (region, agency, department, etc) can be derived from a unit based on organization hierarchy.
Unit Identifier
  • A code used within the interagency wildland fire community to uniquely identify a particular government organizational unit or a non-government organization recognized by NWCG as a wildland fire cooperator.
Unit, Home
Unit, Jurisdictional
  • The governmental entity having overall land and resource management responsibility for a specific geographical area as provided by law.
    • Definition Extension: 1) Ultimately responsible for the fire report to account for statistical fire occurrence; 2) Responsible for setting fire management objectives; 3) Jurisdiction cannot be re-assigned by agreement; 4) The nature and extent of the incident determines jurisdiction (for example, Wildfire vs. All Hazard); 5) Responsible for signing a Delegation of Authority to the Incident Commander.
Unit, Protecting
  • The entity responsible for providing direct incident management and services to a given area pursuant to its jurisdictional responsibility or as specified by law, contract or agreement.
    • Definition Extension: 1) Protection can be re-assigned by agreement; 2) The nature and extent of the incident determines protection (for example - Wildfire vs. All Hazard.)
Unit, Provider
  • Any government organization that is a source of resources for response or mutual aid support to an incident, whether in the field, at the scene of an incident, or operations center.  This includes government organizations that administer contracts or agreements for resources.
Unity of Command
  • The concept by which each person within an organization reports to one and only one designated person. 
Unity of Effort
  • A command philosophy that encourages leaders to work together to find common ground and act in the best interest of those responding to the incident, the public, and the resources that are threatened. 
Unlined Fire Hose
  • Hose commonly of cotton, linen, or synthetic fiber construction without rubber tube or lining, often used for wildfires because of its light weight and self protecting (weeping) characteristics; such hose is attached to first-aid standpipes in buildings. At a specified flow, friction loss in unlined hose of a stated diameter is about twice that of lined fire hose. 
Unplanned Ignition
Unprotected Lands
  • Areas for which no fire organization has responsibility for management of a wildfire authorized by law, contract, or personal interest of the fire organization (e.g., a timber or rangeland association).
Upper Level (Cold) Low
  • Upper Level Disturbance, Cold Low Aloft: A circulation feature of the upper atmosphere where pressure, at a constant altitude, is lowest. Winds blow counter-clockwise around the center in an approximately circular pattern. Upper level lows are usually quite small. The mechanics of these upper lows is such that a pool of cool moist air always accompanies their development. There is often no evidence of low pressure at the earth's surface. An upper low may exist above a surface high pressure system. 
Upper Level (Cold) Trough
  • Trough, Trough Aloft, Upper Level [Cold] Low: An elongated area of relatively low pressure, at constant altitude, in the atmosphere. The opposite of an upper level ridge. Upper level troughs are usually oriented north-south with the north end open. That is, air currents moving from west to east around the earth flow around three sides of the trough then turn eastward rather than toward the west, as in the case of a closed circulation. A large upper level trough may have one or more small upper level closed low circulation systems within it. 
Upper Level High
  • Upper High, High Aloft, Upper Level Ridge: A circulation feature of the upper atmosphere where pressure, at a constant altitude, is higher than in the surrounding region. Winds blow clockwise around an upper level high. Air in an upper level high is usually subsiding. This results in comparatively warm dry air with light winds over a large area. An upper level high may exist without there being high pressure at the earth's surface. 
Upper Level Ridge
  • (Upper Level High, Ridge Aloft) An elongated area of relatively high pressure, at a constant altitude, in the atmosphere. The opposite of an upper level trough. Upper level ridges are often oriented north-south, alternating between upper level troughs, however, during summer they may assume random orientations and vast dimensions. 
Use Level
  • The appropriate ratio of liquid foam concentrate to water recommended by the chemical manufacturer for each class of fire, usually expressed as a percent (such as 0.5%). 
Use of Wildland Fire
Useful Load
  • Maximum computed gross weight minus equipped weight of a helicopter. 
V Pattern
  • Characteristics fire cone-shaped pattern left by a fire on a wall, at or near its point of origin. 
Values at Risk
  • The elements of a community or natural area considered valuable by an individual or community that could be negatively impacted by a wildfire or wildfire operations. These values can vary by community and can include diverse characteristics such as homes, specific structures, water supply, power grids, natural and cultural resources, community infrastructure, and other economic, environmental, and social values.
Values To Be Protected
  • Include property, structures, physical improvements, natural and cultural resources, community infrastructure, and economic, environmental, and social values. 
Vapor Suppression
  • Creating a seal with foam which prevents a release of flammable vapors from fuels. 
  • Any changing characteristic; in statistics, a measurable characteristic of an experimental unit. 
Variable Ceiling
  • A ceiling of less than 3,000 feet (900 m) which rapidly increases or decreases in height by one or more reportable values during the period of observation. 
Variable Danger
  • Resultant of all fire danger factors that vary from day to day, month to month, or year to year (e.g., fire weather, fuel moisture content, condition of vegetation, variable risk) 
Variable Sky Condition
  • A sky condition that varies between reportable values of sky cover amounts during the period of observation. 
Variable Visibility
  • A condition when the prevailing visibility is less than 3 miles (5 km) and rapidly increases and decreases by one or more reportable values during the period of observation. 
Variable Wind Direction
  • Wind direction which varies by 60 degrees or more during the period of time the wind direction is being determined. 
  • Directions of fire spread as related to rate of spread calculations (in degrees from upslope). 
Vegetative Regeneration
  • Development of new aboveground plants from surviving plant parts, such as by sprouting from a root crown or rhizomes. Even if plants form their own root system, they are still genetically the same as the parent plant. 
Vegetative Reproduction
  • Establishment of a new plant from a seed that is a genetically distinct individual. 
Vehicle Fire
  • Fire originating in or on a vehicle or mobile equipment. 
  • The release of enclosed smoke and heat from a structure by creating openings in it, as by hacking a hole in the roof, to allow free passage of air. 
Ventilation Factor
  • A numerical value relating the potential of the atmosphere to disperse airborne pollutants from a stationary source, calculated by multiplying the mixing height by the transport wind speed. 
Ventilation Index
  • A measure of the volume rate of horizontal transport of air within the mixing layer, per unit distance, normal to the wind. Units are measured in square meters per second or knot-feet. 
Vertical Fuel Arrangement
  • Fuels above ground and their vertical continuity, which influences fire reaching various levels or vegetation strata. 
Vertical Temperature Profile
  • Plot of the actual dry-bulb temperature against height above the earth's surface, most commonly determined by a RAWINSONDE observation. 
Very High Frequency (VHF-AM)
  • Radio frequency range from 30 MHz to 299 MHz. The sub-bands most commonly used by fire are:
    • VHF-FM Lo band: Frequency Modulation 30 MHz - 80 MHz, of which fire frequencies are between 30 MHz and 50 MHz.
    • VHF-FM Hi band: Frequency Modulation 150 MHz - 174 MHz. This is the most widely used band by fire agencies.
    • VHF-AM: Amplitude Modulation. This band is commonly referred to as the "Victor or VHF" band. The frequency range is from 118 MHz to 136 MHz. The only authorized use of this band is for aviation. The FAA controls and assigns all frequencies within this sub-band. 
VHF Omnidirectional Radio Range (VOR)
  • System of radio navigation in which any magnetic bearing relative to a special radio transmitter on the ground may be chosen and flown by an aircraft pilot. 
  • A subjective assessment of the health of individual plants in similar site and growing conditions; or a more specific measure based upon a specific facet of growth, such as seed stalk or tiller production per plant or per unit area. 
  • Thickness of a liquid, the degree to which it resists flow. 
Viscous Water
  • Water that contains a thickening agent to reduce surface runoff; tends to cling to burning fuels and spread in layers that are several times thicker than plain water, thereby having an increased capacity to absorb heat, cool fuel, and exclude oxygen. Also known as thickened water. 
Visual Flight Rules Conditions (VFR)
  • Basic weather conditions prescribed for flight under Visual Flight Rules: ceiling above 1,000 feet (300 m) and flight visibility in excess of 3 miles (5 km). 
Visual Greenness (VG)
  • An NDVI-derived image of vegetation greenness compared to a very green reference such as a golf course. 
Visual Range
  • Maximum distance at which a given object can just be seen by an observer with normal vision. 
Visual Resource Management (VRM)
  • The inventory and planning actions taken to identify visual values and to establish objectives for managing those values; and the management actions taken to achieve the visual management objectives. 
Visual Resources
  • The visible physical features on a landscape (e.g., land, water, vegetation, animals, structures and other features). 
Visual Search
  • A systematic and thorough scan of the wildland fire environment for an object or feature as it relates to seeing or sight. This scan may be aided by magnification when necessary.
  • Readily changeable into vapor at low temperatures. 
  • Readily vaporized organic materials which, when mixed with oxygen, are easily ignited. 
Volunteer Fire Department (VFD)
  • A fire department of which some or all members are unpaid. 
Volunteer Firefighter
  • Legally enrolled firefighter under the fire department organization laws who devotes time and energy to community fire service without compensation other than Worker's Compensation or other similar death and injury benefits. 
Vortex Turbulence
  • Miniature whirlwinds trailing from the wingtips of any aircraft in flight. Vortex will be in the form of a horizontal whirlwind with velocities up to 25 mph (40 km) per hour or more. Also created by action of rotor blades on helicopters; these whirlwinds tend to move downward toward the ground. If an aircraft flies low over a fire, vortices may reach the ground and suddenly cause violent and erratic fire behavior. 
Walk Test
  • The walk test is designed to determine the ability to carry out light duties. It consists of a one-mile test with no load that approximates an aerobic fitness score of 35. A time of 16 minutes, the passing score for this test, ensures the ability to meet emergency and evacuate to a safety zone. 
Warm Front
  • The leading edge of a relatively warm air mass which moves in such a way that warm air replaces colder air that moves away from a region. Winds associated with warm frontal activity are usually light and mixing is limited. The atmosphere is relatively stable when compared to cold front activity.  Source:  http://glossary.ametsoc.org/wiki/Warm_front
  • The official delegation of authority to contracting officers and procurement officers establishing the dollar amount and type limits for acquisitions.
Water Bar
  • A shallow channel or raised barrier, e.g., a ridge of packed earth or a thin pole laid diagonally across the surface of a road or trail so as to lead off water, particularly storm water. (Frequently installed in firelines on steep slopes to prevent erosion.) 
Water Expansion Pumping System (WEPS)
  • Apparatus utilizing an air compressor and positive displacement pump coupled to the same engine, plumbed to a non-pressurized tank, for producing foam. The operation involves injecting compressed air into a liquid stream containing a suitable foaming agent. 
Water Expansion System (WES)
  • Apparatus utilizing a pressurized tank, hose, and nozzle for producing foam by injection of compressed air or gas into a liquid stream downstream from the pumping source. The liquid stream must contain a suitable foaming agent. 
Water Hammer
  • A force created by the rapid acceleration or deceleration of water, commonly created by opening or closing a valve too quickly. Pressures developed in a water hammer, proportional to the mass multiplied by the square of the velocity, can damage a pipe or hose. 
Water Source
  • Any strategically located supply of water that is readily available for pumps, tanks, trucks, helicopters, or fire camp use. 
Water Supply Map
  • A map showing location of supplies of water readily available for pumps, tanks, trucks, camp use, etc. 
Water Tender
  • Any ground vehicle capable of transporting specified quantities of water. 
Water Thief
  • A type of bleeder valve designed for installation at convenient points in hose lines to permit drawing off water for filling backpack pumps or other use without interfering with pump or nozzle operation. 
  • Waterway: Any body of water including lakes, rivers, streams and ponds whether or not they contain aquatic life.  
    Source: 2009 Interagency Policy for Aerial Deliver of Wildland Fire Chemicals near Waterways, https://www.fs.fed.us/t-d/programs/wfcs/wf

  • A disturbance that transfers energy from one point to another point and may take the form of a deformation of pressure or temperature. In the atmosphere such disturbances may result in major storms or merely result in changes in cloud, wind and temperature conditions. Development of a wave on a front usually slows the advance of the front due to transfer of energy to the wave development and movement. 
Weather Advisory
  • In aviation forecasting, an expression of hazardous weather conditions not predicted in the zone weather forecast, as they affect the operation of air traffic. 
Weather Information Management System (WIMS)
  • A centralized weather data processing system at which daily fire danger ratings are produced. 
Weighted Monthly Occurrence
  • Part of the National Fire Danger Rating System (NFDRS). Number used to determine seasonal risk class for a protection unit, calculated by multiplying peak monthly average by two and adding seasonal monthly average. 
  • The contractor furnishes all equipment operating supplies.
Wet Foam
  • A low expansion foam type with few and varied bubbles and rapid drain time which is used for rapid penetration and fire extinguishment. 
Wet Line
  • A line of water, or water and chemical retardant, sprayed along the ground, and which serves as a temporary control line from which to ignite or stop a low-intensity fire. 
Wet Storage
  • Fire retardants mixed with water and stored in tanks at air attack bases for immediate use by airtankers. 
Wet Water
  • Water with added chemicals, called wetting agents, that increase water's spreading and penetrating properties due to a reduction in surface tension. 
Wet-bulb Depression
Wet-bulb Temperature
  • The lowest temperature to which air can be cooled by evaporating water into it at a constant pressure when the heat required for evaporation is supplied by the cooling of the air. It is measured by the wet bulb thermometer, which usually employs wetted wicking on the bulb as a cooling (through evaporation) device.  Source:  http://glossary.ametsoc.org/wiki/Wet-bulb_temperature
Wet-bulb Thermometer
Wetting Agent
  • A chemical that when added to water reduces the surface tension of the solution and causes it to spread and penetrate exposed objects more effectively than the untreated water. 
Wetting Rain
  • A widespread rain that over an extended period of time significantly reduces fire danger. One-tenth of an inch may be sufficient to reduce fire danger in grass fuel models. One half inch may be necessary for timber fuels under closed canopies. 
  • The distance from the centerline of the front axle to the centerline of the rear axle. For a tandem rear axle vehicle the center line is midpoint between the centers of the two rear axles. 
  • A loose limb, top, or piece of bark lodged in a tree, which may fall on anyone working beneath it. 
Wildfire Response Strategies
  • The range of options available for response to a wildfire. 
    • Definition Extensions: 1)  Common strategies include Monitor, Confine, Contain, Point/Zone Protection, and Suppression, but hybrids and novel strategies may also be developed as the situation demands.  2)  One or more strategies may be employed on any given wildfire.  The strategy or strategies being employed may vary temporally or spatially.
  • An area in which development is essentially non-existent, except for roads, railroads, powerlines, and similar transportation facilities. Structures, if any, are widely scattered. 
Wildland Fire
Wildland Fire Assessment System (WFAS)
  • An internet-based information system, providing national views of weather and fire potential, including national fire danger and weather maps and satellite-derived greenness maps. 
Wildland Fire Investigator
  • An individual responsible for determining all or part of a wildland fire's origin, ignition sequence, cause and potential responsibility for that cause.
Wildland Fire Leadership Principles
  • Eleven principles describing tangible behaviors that reflect and demonstrate the wildland fire leadership values. The eleven principles are:
    • Be proficient in your job.
    • Make sound and timely decisions.
    • Ensure tasks are understood, supervised, and accomplished.
    • Develop your subordinates for the future.
    • Know your subordinates and look out for their well-being.
    • Keep your subordinates informed.
    • Build the team.
    • Employ your subordinates in accordance with their capabilities.
    • Know yourself and seek improvement.
    • Seek responsibility and accept responsibility for your actions.
    • Set the example. 
Wildland Fire Leadership Values
  • Three guiding values that should be the basis for the decisions that leaders make. The three values are:
    • Duty ─ How a leader values their job. Duty begins with everything required by law and policy, but is much more than that. A leader commits to excellence in all aspects of their professional responsibility so that when the job is done they can look back and say, "I couldn't have given any more."
    • Respect ─ How a leader values their co-workers. Respect for the individual forms the very basis for the rule of law in America. This value reminds leaders that those who follow are their greatest resource. Not all followers will succeed equally, but they all deserve respect.
    • Integrity ─ How a leader values himself or herself. An individual cannot be in charge of others unless they are in charge of their own actions. People of integrity separate what is right from what is wrong and act according to what they know is right, even at personal cost.
Wildland Fire Management Information (WFMI)
  • A web site providing current weather and lightning data, as well as historic fire occurrence data. NWCG Unit Identifiers are also maintained on the site. 
Wildland Fire Module
  • A group of 7-10 highly skilled personnel specifically associated with the planning and implementation of planned and unplanned wildland fire and hazardous fuels treatments. Maybe classified as a Type 1 or Type 2 dependent on qualifications and experience. 
Wildland Fire Serious Accident
  • Any accident where one or more fatalities occur and/or three or more personnel are inpatient hospitalized as a direct result, or in support of wildland fire suppression or prescribed fire operations. Accident may result in substantial property or equipment damage of $250,000 or more. 
Wildland Urban Interface (WUI)
Wind Direction
Wind Profile
Wind Shear
  • A variation in wind speed and/or direction in a layer of the atmosphere or between layers. The variation may be in the horizontal or vertical dimensions and may result in significant turbulence depending upon the magnitude of the wind speed/direction differences. A strong wind shear may act like an inversion and inhibit plume rise. It may also fracture the smoke plume, not allowing smoke to rise much above terrain levels. A strong horizontal anticyclonic shear results in downward motion and may bring smoke aloft to the surface.  Source:  http://glossary.ametsoc.org/wiki/Wind_shear
Wind Shift
  1. For aviation purposes, a change in the average wind direction of 45 degrees or more which takes place in less than 15 minutes if the wind speed during this period is 6 knots (3 m/s) or greater.
  2. For ground observation purposes, a change of at least 45 degrees in the direction of a significant wind, which occurs in a relatively short time frame. 
Wind Speed
  1. Wind, in miles per hour, measured at 20 feet above open, level ground or as adjusted to meet this standard to compensate for height of ground cover, uneven ground, and nearby obstructions.
  2. (NFDRS) Wind, in mph, measured at 20 feet above ground, or above the average height of vegetation, and averaged over at least a 10-minute period. Also known as wind velocity. 
Wind Vectors
Wind Vortex Flame Wrap
  • A char pattern that is created by the passage of wind around the trunk of a tree or pole-like object that creates vortices on the lee side and an area of stability. The area of stability allows the heat and char pattern to rise higher on the lee side of the object. Generally, the stronger the wind, the higher the wind vortex flame wrap will be. While this is not a fire pattern indicator, it is a general indication of the direction of the wind at the time the pattern was created.
Wind-driven Wildland Fire
  • A wildland fire that is controlled by a strong consistent wind. 
  • Tree that has been uprooted or broken off by wind. 
Windrow Burning
  • Burning slash that has been piled into long continuous rows. Also includes wildfire in vegetation planted to protect improvements or agriculture. 
Winds Aloft
Windspeed Meter
  • A handheld device which indicates wind speed, usually in miles per hour. 
Woody Fuel Moisture
  • In NFDRS, a calculated value representing the approximate moisture content of the live woody vegetation in the rating area expressed as a percentage of the oven dry weight of the sample. 
Woody Vegetation Condition
  • Part of the National Fire Danger Rating System (NFDRS). A code reflecting the moisture content of the foliage and small twigs [less than 1/4 inch (0.6 cm)] of living woody plants. 
Work Capacity Test (WCT)
  • The Work Capacity Test (WCT) is a test to ensure a person is physically capable of meeting the minimum fitness requirement associated with assigned wildfire or prescribed fire duties as described in the NWCG Standards for Wildland Fire Position Qualifications, PMS 310-1.  Below are the three defined duty levels with examples of associated essential functions:  
    • Arduous
      • Arduous duty field work requires above-average endurance and superior conditioning.  Duties may include an occasional demand for extraordinarily strenuous activity in emergency situations under adverse environmental conditions over extended periods. The pace of work typically is set by the emergency condition.  Essential functions include, but are not limited to: running, walking or hiking, climbing, jumping, twisting, bending, lifting more than 50 pounds, and carrying 45 pounds or more for extended periods over difficult terrain. 
    • Moderate
      • Moderate duty field work requires the average endurance and conditioning of an individual who possesses complete control of all their physical faculties. Occasional demands may be required for moderately strenuous activities in emergencies over long periods. The pace of work is usually set by the current environmental conditions.  Essential functions include, but are not limited to: considerable walking over irregular ground, standing for long periods, lifting 25 to 50 pounds, climbing, bending, stooping, squatting, twisting, and reaching.
    • Light
      • Light duty mainly involves office-type work with occasional field activity characterized by light physical exertion requiring basic good health.  Individuals almost always can govern the extent and pace of their physical activity.  Essential functions include, but are not limited to: climbing stairs, standing, operating a vehicle, and long hours of work, as well as some bending, stooping, or light lifting.
  • The WCT consists of three separate levels of tests which correspond with the three duty types.  The tests are defined as follows:

    • Pack Test - This is a job-related test to determine an individual’s ability to perform the minimum standards of arduous duty.  It consists of completing a 3-mile walk over level terrain in 45 minutes or less while carrying a 45-pound pack.  
    • Field Test – This is a job-related test to determine an individual’s ability to perform the minimum standards of moderate duty. It consists of completing a 2-mile walk over level terrain in 30 minutes or less while carrying a 25-pound pack.
    • Walk Test – This is a job-related test to determine an individual’s ability to perform the minimum standards of light duty.  The test consists of completing a 1-mile walk over level terrain in 16 minutes or less with no load.
  • For more information about the Work Capacity Test consult the Work Capacity Test Administrator’s Guide, PMS 307.
Work Rate
  • A daily, hourly, or mileage rate shall apply when equipment is under hire as ordered by the government and on shift, including relocation of equipment under its own power.
Work/Rest Ratio
  • An expression of the amount of rest that is required for each hour an individual is in work status. Current NWCG guidelines require one hour of rest for every two hours in work status. 
Woven Jacket Fire Hose
  • Fire hose of conventional construction, woven on looms from fibers of cotton or synthetic fibers. Most fire department hose is double jacketed (i.e., it has an outer jacket protecting the inner one against wear and abrasion). 
  • A hose connection with two outlets permitting two connections of the same coupling diameter to be taken from a single supply line. 
Zone Weather Forecast
  • A portion of the general fire weather forecast issued on a regular basis during the normal fire season specifically to fit the requirements of fire management needs; i.e., time, areas, and weather elements. These zones or areas are a combination of administrative and climatological areas, usually nearly the size of an individual forest or district.