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)
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.