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 About the NWCG Glossary page or the NWCG User Guide for the Glossary of Wildland Fire, PMS 937.

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)
  • 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.