- A -

ABORT AREA: A designated area where unused quantities of water or fire retardant may be jettisoned, usually to permit an air tanker 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: Total amount of water vapor in the air.

ACCELERANT: Any substance applied to fuel to expedite the burning process.

ACCEPTABLE BURN: Maximum average area burned over a specified period of years that is considered an acceptable loss for a specified area under organized fire suppression. (Syn. ALLOWABLE BURNED AREA)

ACCEPTABLE DAMAGE: Damage which does not seriously impair the flow of economic and social benefits from wildlands.

ACCEPTABLE FIRE RISK: The potential fire loss a community is willing to accept rather than provide resources to reduce such losses.

ACCESSIBILITY BURN: Burning of understory prior to the sale of forest products to improve the efficiency of timber marking and harvesting. (Syn. PREMARKING BURN)

ACTION PLAN: Any tactical plan developed by any element of ICS in support of the incident action plan. (see also INCIDENT ACTION PLAN)

ACTIONABLE FIRE: Any fire that requires suppression, especially a fire started or allowed to spread in violation of law, ordinance, or regulation.

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 wildfire on which suppression action has not reached an extensive mopup stage. (Syn. GOING FIRE)

ACTIVE RESOURCES: Resources checked in and assigned work tasks on an incident. (Syn. ASSIGNED RESOURCES)

ACTIVITY FUELS: Fuels resulting from, or altered by, forestry practices such as timber harvest or thinning, as opposed to naturally created fuels.

ADIABATIC PROCESS: Thermodynamic change of state in which no heat is added or subtracted from a system; compression always results in warming, expansion in cooling.

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.

ADVECTION: The transfer of atmospheric properties by the horizontal movement of air, usually in reference to the transfer of warmer or cooler air, but may also refer to moisture.

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): Inclusive term applied to equipment designed to ignite wildland fuels from an aircraft. (see also DELAYED AERIAL IGNITION DEVICES, HELITORCH, PING-PONG BALL SYSTEM, PLASTIC SPHERE DISPENSER)

AERIAL OBSERVER A person specifically assigned to discover, locate, and report wildland fires from an aircraft and to observe and describe conditions at the fire scene.

AERIAL PHOTO INTERPRETER: A person skilled in identification and measurements of natural and cultural features on aerial photographs.

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.

AGENCY: An agency is a division of government with a specific function, or a nongovernmental organization (e.g., private contractor, business, etc.) that offers a particular kind of assistance. In ICS, agencies are defined as jurisdictional (having statutory responsibility for incident mitigation), or assisting and/or cooperating (providing resources and/or assistance). (see also SUPPORTING AGENCY, and COOPERATING AGENCY)

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.

AGENCY EXECUTIVE OR ADMINISTRATOR: Line officer (or designee) of the agency or jurisdiction that has responsibility for the incident. These usually include; NPS Park Superintendent, BIA Agency Superintendent, USFS Forest Supervisor, BLM District Manager, FWS Refuge Manager, State Forest Officer, Fire Chief.

AGENCY REPRESENTATIVE (AREP): An individual assigned to an incident from an assisting or cooperating agency who has been delegated authority to make decisions on matters affecting that agency's participation at the incident. Reports to the incident liaison officer.

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. (see also RELOAD BASE)

AIR CONTAMINANT: An airborne dust, fume, gas, mist, odor, smoke, vapor, soot, pollen, carbon, acid or particulate matter or any combination thereof.

AIR MASS: An extensive body of air having the same properties of temperature and moisture in a horizontal plane.

AIR OPERATIONS BRANCH DIRECTOR (AOBD): The person primarily responsible for management of air operations on an incident

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. (Syn. SELF-CONTAINED BREATHING APPARATUS - SCBA) (see also RESPIRATOR)

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 CONTROL REGION: A primary air quality administrative area, designated in accordance with the provisions of the 1970 Clean Air Act, on the basis of geographical and meteorological considerations.

AIR QUALITY MAINTENANCE AREA (AQMA): An area that has been identified by an Air Quality Regulatory Agency to have the potential for exceeding any federal or state ambient air quality standard due to projected growth and development.

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): 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.

AIR TANKER: Fixed-wing aircraft certified by FAA as being capable of transport and delivery of fire retardant solutions.

AIR TRANSPORTABLE MODULAR UNIT (ATMU): A weather data collection and forecasting facility consisting of four modules, weighing a total of 282 pounds and occupying 27.1 cubic feet of space when transported. Used by incident meteorologists on an incident. (see also INCIDENT METEOROLOGIST and MICRO-REMOTE ENVIRONMENTAL MONITORING SYSTEM)

AIRBORNE PARTICULATES: Total suspended particulate matter found in the atmosphere as solid particles or liquid droplets. Chemical composition of particulates varies widely, depending on location and time of year. Airborne particulates include: windblown dust, emissions from industrial processes, smoke from the burning of wood and coal, and the exhaust of motor vehicles.

ALIDADE: A sighting device used by lookouts to determine the horizontal bearing and sometimes the vertical angle of a fire from a lookout. (Syn. OSBORNE FIREFINDER) (see also FIREFINDER MAP)

ALLOCATED RESOURCES: Resources dispatched to an incident, that have not yet checked in. (see also ASSIGNED RESOURCES and AVAILABLE RESOURCES)

ALLOWABLE BURNED AREA: Maximum average area burned over a specified period of years that is considered an acceptable loss for a specified area under organized fire suppression. (Syn. ACCEPTABLE BURN)

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: Air of the surrounding environment.

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.

ANEMOMETER: An instrument designed to measure wind speed.

ANNUAL: A plant completing its life cycle in a year or less.

ANTICYCLONE: An area of high atmospheric pressure with closed clockwise circulation. (see also SURFACE HIGH, HIGH PRESSURE RIDGE)

APPROVED: In fire service terminology, that which is inspected and listed by recognized firetesting agencies. The term as used in National Fire Protection Association standards means approval by the authority having jurisdiction, such as the fire chief, insurance inspection department, or other agency that enforces standards or regulations.

ARAMID: 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 IMT's 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.

ARSON FIRE: A wildfire willfully ignited by anyone to burn, or spread to, vegetation or property without consent of the owner or his/her agent. (Syn. INCENDIARY FIRE)

ASPECT: Cardinal direction toward which a slope faces. (see also EXPOSURE)

ASPIRATE (foam): To draw in gases (or other substances); nozzle aspirating systems draw air into the nozzle to mix with the foam solution.

ASSIGNED RESOURCES: Resources checked in and assigned work tasks on an incident. (Syn. ACTIVE RESOURCES) (see also ALLOCATED RESOURCES and AVAILABLE RESOURCES)

ATMOMETER: An instrument that provides an approximate measure of evapotranspiration by measuring the water loss from an artificial evaporating surface.

ATMOSPHERIC INVERSION: (1) 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). (2) 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. (see also INVERSION, ATMOSPHERIC STABILITY, and STABLE LAYER OF AIR)

ATMOSPHERIC PRESSURE: The force exerted by the weight of the atmosphere, per unit area.

ATMOSPHERIC STABILITY: The degree to which vertical motion in the atmosphere is enhanced or suppressed. Vertical motions and pollution dispersion are enhanced in an unstable atmosphere. Thunderstorms and active fire conditions are common in unstable atmospheric conditions. Stability suppresses vertical motion and limits pollution dispersion. (see also
INVERSION, ATMOSPHERIC INVERSION, and STABLE LAYER OF AIR)

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.

AUTOMATIC DIRECTION FINDER (ADF): An aircraft radio navigational receiver operating in the low frequency bands.

AUTOMATIC LIGHTNING DETECTION SYSTEM (ALDS): An electronic system that detects cloud-to-ground lightning strikes by their electrical discharges and plots their locations.

AVAILABLE FUEL: (1) That portion of the total fuel that would actually burn under various environmental conditions. (2) Fuel available for use in a motor vehicle, aircraft, or other motorized equipment.

AVAILABLE FUEL ENERGY: Amount of heat released per unit area when the available fuel burns, often expressed in Btu's per square foot.

AVAILABLE RESOURCES: Resources assigned to an incident and available for assignment. (see also ALLOCATED RESOURCES, ASSIGNED RESOURCES)

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: The mathematical average of the maximum and minimum drybulb temperatures measured at a fire weather station from one basic observation time to the next.

AVERAGE WORST DAY: Average fire danger of the highest 15% of the days occurring in the average worst year.

AVERAGE WORST YEAR: Third worst fire season in the last ten, as determined by the sum of daily danger or burning indices during the regularly declared fire season; use the same number of days each year to determine these totals.

AVOIDANCE: A smoke emission control strategy that considers meteorological conditions when scheduling prescribed fires in order to avoid incursions into smoke sensitive areas.

AZIMUTH: Horizontal angle or bearing of a point measured clockwise from true (astronomic) north.

AZIMUTH CIRCLE: A circle graduated in 360 degrees in a clockwise direction from true (astronomic) north.

- B -       Back to top

BACK AZIMUTH: Angle or bearing 180 degrees opposite of azimuth.

BACKBURN: Used in some localities to specify fire set to spread against the wind in prescribed burning.

BACKDRAFT: 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.

BACKFIRE: A fire set along the inner edge of a fireline to consume the fuel in the path of a wildfire and/or change the direction of force of the fire's convection column. (see also BURN OUT)

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). (see also DRIP TORCH, FLAME THROWER) (Syn. BURNING TORCH)

BACKFIRING: 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: 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.
BACKING WIND: Wind that changes direction in a counter clockwise motion.

BACKPACK PUMP: A portable sprayer with hand-pump, fed from a liquid filled container fitted with straps, used mainly in fire and pest control. (see also BLADDER BAG)

BAFFLE: 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.

BAROMETER: An instrument for measuring the pressure of the atmosphere. The two principal types are the mercurial and the aneroid.

BARRIER: Any obstruction to the spread of fire. Typically an area or strip devoid of combustible fuel.

BASE: (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. (see also CAMP)

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 MANAGER: Person responsible to the facilities unit leader for providing all services, supplies, and non-technical coordination for all units operating within the incident base.

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.

BASELINE: 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.
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.

BEARING: The horizontal direction to or from any point, usually measured clockwise from true north, or some other reference point through 360 degrees.

BEAUFORT WIND SCALE: A system of estimating and reporting wind speeds. In its present form for international meteorological use it equates (a) Beaufort force (or Beaufort number), (b) wind speed, (c) descriptive term, and (d) visible effects upon land objects or sea surface.

BEHAVE: A system of interactive computer programs for modelling fuel and fire behavior, comprised of two systems: BURN and FUEL.

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.

BERM: A ridge of soil and debris along the outside edge of a fireline, resulting from line construction. (see also THROW OUT)

BEST AVAILABLE CONTROL MEASURES (BACM): Control measures to be developed by Environmental Protection Agency (EPA) which apply to residential wood combustion, fugitive dust, and prescribed and silvicultural burning in "serious" PM-10 non-attainment areas. BACM is more stringent than RACM. Final guidance on BACM is still being developed.

BEST AVAILABLE CONTROL TECHNOLOGY (BACT): An emission limitation based on the maximum degree of emission reduction which (considering energy, environmental, and economic impacts, and other costs) is achievable through application of production processes and available methods, systems, and techniques. In no event does BACT permit emissions in excess of those allowed under any applicable Clean Air Act provisions. Use of the BACT concept is allowable on a case-by-case basis for major new or modified emissions sources in attainment areas and applies to each regulated pollutant.

BIOLOGICAL SEVERITY: The degree of biological impact of a fire on various biotic ecosystem components.

BLACKLINE: 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. (see also BACKPACK 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. (see also BURNING BLOCK)

BLOW DOWN: An area of previously standing timber which has been blown over by strong winds or storms.

BLOWUP: 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. (see also EXTREME FIRE BEHAVIOR, FIRE STORM and FLARE-UP)

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 in order to identify reasons for both good and poor action and to recommend or prescribe ways and means of doing a more 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.

BOLE: The trunk of a tree.

BONE YARD: A mopup term. (1) 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: The air in immediate contact with a fuel particle.

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.

BRANCH: 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 59.5° to 60.5° F), measured at standard atmospheric pressure.

BROADCAST BURNING: Intentional burning 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.

BRUSH: 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.

BUBBLE: 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.

BUCKING: Sawing through the bole of a tree after it has been felled.

BUILD-UP: (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.

BULK DENSITY: Weight per unit volume. For fuels, this is usually expressed as pounds per cubic foot; for soils, grams per cubic centimeter.

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. (Syn. MOVEUP METHOD)

BURN: (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. a) First Degree Burn: A burn which causes only pain, redness, and swelling. b) Second Degree Burn: A burn in which the skin is blistered. c) Third Degree Burn: A flesh burn in which charring occurs.

BURN BOSS: Person responsible for supervising a prescribed fire from ignition through mopup.

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.

BURN OUT: Setting fire inside a control line to consume fuel between the edge of the fire and the control line. (see also BACKFIRE)

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.

BURNING BAN: A declared ban on open air burning within a specified area, usually due to sustained high fire danger.

BURNING BLOCK: In prescribed burning, an area having sufficiently uniform conditions of stand and fuel to be treated uniformly under a given burning prescription. NOTE: The size ranges from the smallest that allows an economically acceptable cost per acre, up to the largest that can conveniently be treated in one burning period. (see also BLOCK PLAN)

BURNING CONDITIONS: The state of the combined factors of the environment that affect fire
behavior in a specified fuel type.

BURNING INDEX: An estimate of the potential difficulty of fire containment as it relates to the flamelength at the head of the fire. 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 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 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). (see also DRIP TORCH, FLAME THROWER) (Syn. BACKFIRE TORCH)

BURNING-INDEX METER A device used to determine the burning index for different combinations of burning-index factors.

BURN PATTERNS: 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. They can be used to trace a fire's origin.

BUYING TEAM: A team that supports the procurement effort through the local administrative staff and is authorized to procure a wide range of services, supplies, land and equipmental rentals. In addition, the buying team leader has the responsibility of coordinating property accountability with the supply unit leader.
BUYS BALLOT'S LAW: If a person stands with his back to the wind, the high atmospheric pressure is found to his right in the Northern Hemisphere. The high pressure on the right moves clockwise and outward from the cell. The low pressure on the left moves counterclockwise and toward the center of the cell. Therefore, the general air circulation between the high and the low cell is from right to left.

- C -     Back to top

CACHE: 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.

CAMP: 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. (see also BASE)

CAMP MANAGER: Person responsible to the facilities unit leader for providing all services, supplies, and non-technical coordination for all units within the camp. There may be one or more camps per incident, each with a camp manager.

CANDLING: The burning of the foliage of a single tree or a small group of trees, from the bottom up. (Syn. TORCHING)

CANOPY: The stratum containing the crowns of the tallest vegetation present, (living or dead) usually above 20 feet.

CARBON DIOXIDE (COD: 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.

CARCINOGEN: 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.

CARRIED WET: Booster hose carried full of water during mild weather to speed discharge of water on fire without filling or priming from tank:

CARRIER FUELS: The fuels that support the flaming front of the moving fire.

CASUALS: Emergency firefighters employed to cope with a sudden and unexpected fire-caused emergency, or potential for extreme fire behavior, which threatens damage to property under public management. (see also EMERGENCY FIREFIGHTER)

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)].

CATFACE: Defect on the surface of a tree resulting from a wound where healing has not reestablished the normal cross-section.

CEILING: (1) Height above the earth's surface of the lowest layer of clouds or obscuring phenomena aloft that is not classified as a thin layer or partial obscuration, that together with all lower clouds or obscuring phenomena covers more than half the sky as detected from the point of observation. (2) Maximum height of a temporary flight restriction (TFR).

CELSIUS: A temperature scale with 0° as the freezing point of water and 100' as the boiling point of water at sea level.

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.

CENTIPOISE (CP): Standard unit of viscosity equal to 0.01 poise, the cP unit of viscosity. Water at 20 degrees C has viscosity of 1.002 cP.

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.

CHAIN: 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.

CHAR: (1) A charred substance or charred remains. (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.

CHARGED LINE: Hose filled with water under pressure and ready to use. Also called live line. (see also LIVE REEL)

CHASE TRUCK: Vehicle that carries crew gear, supplies, and operational equipment for initial/extended attack.
CHECK-IN: The process whereby resources first report to an incident. Check-in locations include: incident command post (resources unit), incident base, camps, staging areas, helibases, helispots, or direct to the line. (see also REPORTING LOCATIONS)

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.

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.

CHIEF: 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.

CIRRUS: A form of high cloud, composed of ice crystals, which seldom obscures the sun.

CLAIMS SPECIALIST (CLMS): Person responsible to the compensation/claims unit leader for handling all claims-related activities (other than injury) for the incident.

CLASS 1 AREA (AIR QUALITY): Geographic areas designed by the Clean Air Act where only a very small amount or increment of air quality deterioration is permissible.

CLASS II AREAS (AIR QUALITY): All areas of the country not designated Class I. A greater amount of air pollution can be added to these areas than Class I.

CLASS A FOAM: Foam intended for use on Class A or woody fuels; made from hydrocarbonbased 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 OF FIRE (As to kind of fire for purpose of using proper extinguisher):

Class A - Fires involving ordinary combustible materials (such as wood, cloth, paper, rubber, and many plastics) requiring the heat absorbing (cooling) effects of water, water solutions, or the coating effects of certain dry chemicals,
which retard combustion.
Class B - Fires involving flammable or combustible liquids, flammable gases, greases, and similar materials where extinguishment is most readily secured by excluding air (oxygen), inhibiting the release of combustible vapors, or interrupting the combustion chain reaction.
Class C - Fires involving live electrical equipment where safety to the operator requires the use of electrically nonconductive extinguishing agents.
Class D - Fires involving certain combustible metals (such as magnesium, titanium, zirconium, sodium, potassium, etc.) requiring a heat absorbing extinguishing medium not reactive with burning metals.
(see also SIZE CLASS OF FIRE)

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.

CLEAN BURN: Any fire, whether deliberately set or accidental, that destroys all aboveground vegetation and litter, along with the lighter slash exposing the mineral soil.

CLEAR TEXT: The use of plain English in radio communications transmissions. No Ten Codes or agency specific codes are used when using Clear Text.

CLEARING INDEX: A derived value used to indicate smoke dispersal. Formula uses the depth of the mixing layer multiplied by the average wind speed for that layer, divided by 100.

CLIMATE: The prevalent or characteristic meteorological conditions of any place or region, and their extremes.

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.

CLOSURE: Legal restriction, but not necessarily elimination, of specified activities such as smoking, camping, or entry that might cause fires in a given area.

CLOUD: A visible cluster of minute water/ice particles in the atmosphere.

CLOUDY: 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."

COLD FRONT: The leading edge of a relatively cold air mass which displaces and may cause warmer air 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 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.

COLONIZER: Species of vegetation that establish on a burned (or otherwise denuded) site from seed.

COMBINATION NOZZLE: Also called an "adjustable fog nozzle," this nozzle is designed to provide either a solid stream or a fixed spray pattern suitable for applying water, wet water or foam solution.

COMBINATION NOZZLE TIP: Two attached straight stream nozzle tips of different orifice size used to increase or restrict water flow.

COMBUSTION: 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. (see also REACTION INTENSITY)

COMMAND: The act of directing, and/or controlling resources by virtue of explicit legal, agency, or delegated authority.

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.

COMMERCIAL FOREST LAND: Land that is producing, or is capable of producing, crops of industrial wood and is not withdrawn from timber use by statute or administrative regulation.

COMMISSARY: Supply of items such as candy, tobacco products, toilet items, and work clothes that are made available for sale to firefighters working on a wildfire.
COMMISSARY MANAGER (CMSY): Person responsible to the time unit leader for operating the commissary at an incident base or camp.

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.

COMPACTNESS: Spacing between fuel particles.

COMPACTS: Formal working agreements among agencies to obtain mutual aid.

COMPANY: Any piece of (fire) equipment having a full complement of personnel.

COMPASS ROSE: A circle, graduated in degrees, printed on some charts or marked on the ground at an airport or heliport. It is used as a reference to either true or magnetic direction.

COMPENSATION/CLAIMS UNIT: Functional unit within the Finance/Administration Section responsible for financial concerns resulting from property damage, injuries or fatalities at the incident.

COMPENSATION-FOR-INJURY MANAGER Person responsible to the compensation/claims unit leader for administering financial matters arising from serious injuries and deaths occurring at an incident.

COMPLEX: Two or more individual incidents located in the same general area which are assigned to a single incident commander or unified command.

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 permissible payload for helicopters. Computed gross weight is the maximum computed gross weight, from performance charts, at which a helicopter is capable of hovering in ground effect or hovering out of ground effect at stated density altitude.

CONCENTRATE: A substance that has been concentrated; specifically, a liquid that has been made denser, as by the removal of some of its water.

CONDENSATION: The process by which a gas becomes a liquid.

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.

CONDUCTION: Heat transfer through a solid material from a region of higher temperature to a region of lower temperature.

CONFINE A FIRE: The least aggressive wildfire suppression strategy, typically allowing the wildland fire to burn itself out within determined natural or existing boundaries such as rocky ridges, streams, and possibly roads.

CONFLAGRATION: 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).

CONSUMPTION: 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.

CONTAIN A FIRE: A moderately aggressive wildfire suppression strategy which can reasonably be expected to keep the fire within established boundaries of constructed firelines under prevailing conditions.

CONTAINMENT: (1) Completion of a control line around a 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.

CONTOUR MAP: A map having lines of equal elevation that represent the land surface,(Topographic).

CONTROL A FIRE: To complete control line around a fire, any spot fire therefrom, and any interior island to be saved; burn out any unburned area adjacent to the fire side of the control lines, and cool down all hot spots that are immediate threats to the control line, until the lines can reasonably be expected to hold under foreseeable conditions. (Syn. CONTROLLED)

CONTROL FORCE: Personnel and equipment used to control a fire.

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 hot spots that are immediate threats to the control line, until the lines can reasonably be expected to hold under the foreseeable conditions. (Syn. CONTROL A FIRE)

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.

CONTROL LINE: An inclusive term for all constructed or natural barriers and treated fire edges used to control a fire.

CONTROLLING NOZZLE: Shut-off nozzle that permits the nozzle operator to open or close the nozzle or adjust the pattern of the stream.

CONTROL TIME: The time a fire is declared controlled.

CONVECTION: (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. (see also SMOKE PLUME)

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.

CONVERGENCE: 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. 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.

COOPERATIVE FIRE PROTECTION (CFP): A staff unit within the branch of State and Private Forestry or Aviation and Fire Management in the National Forest System, USDA Forest Service.

COOPERATOR: Local agency or person who has agreed in advance to perform specified fire control services and has been properly instructed to give such service.

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.). (see also AGENCY, SUPPORTING AGENCY)

CO-OP FIRE: Refers to federal, state, and local cooperative fire programs.

COORDINATION: 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.

COORDINATED RESOURCE MANAGEMENT: A process that directly involves everyone concerned with resource management in a given planning area degrees/minutes/seconds of latitude and longitude, used to determine or report position or location.
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.

CORROSION: Result of chemical reaction between a metal and its environment (i.e., air, water, and impurities in same).

COST SHARING AGREEMENTS: Agreements between agencies or jurisdictions to share designated costs related to incidents. Cooperative Fire Protection Agreements With States, agencies, and jurisdictions outline the procedures for cost sharing.

COST UNIT: Functional unit within the finance/administration section responsible for tracking costs, analyzing cost data, making cost estimates, and recommending cost-saving measures.

COUNCIL TOOL: Long-handled combination rake and cutting tool, the blade of which is 27 constructed of a single row of three or four sharpened teeth. Also called fire rake, council rake. (see also RICH TOOL)

COUNTER FIRE: Fire set between main fire and backfire to hasten spread of backfire. Emergency firing to stop, delay, or split a fire front, or to steer a fire. Also called draft fire.

COUPLING: Device that connects the ends of adjacent hoses or other components of hose.

COURSE: In aviation, the intended direction of horizontal flight.

COVER: The area on the ground covered by the combined aerial parts of plants expressed as a percent of the total area.

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.

COVER TYPE: The designation of a vegetation complex described by dominant species, age, and form.

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 again the next operational period where they left off.

CREEPING FIRE: Fire burning with a low flame and spreading slowly.

CREW: An organized group of firefighters under the leadership of a crew boss or other designated official.

CREW BOSS: A person in supervisory charge of usually 16 to 21 firefighters and responsible for their performance, safety, and welfare.
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: Those air pollutants designated by the Environmental Protection Agency as potentially harmful and for which ambient air standards have been set to protect the public health and welfare. The criteria pollutants are carbon monoxide, sulfur dioxide, particulate, nitrogen dioxide, ozone, hydrocarbons and lead.

CRITICAL BURNOUT TIME: Total time a fuel can burn and continue to feed energy to the base of a forward-traveling convection column.

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.

CUMULONIMBUS: 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.

CUMULUS: 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 called 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.

CURING: Drying and browning of herbaceous vegetation or slash.

CYCLIC CONTROL: A cockpit control stick for regulating the tilt of the main rotor(s) in relation to the body of the helicopter. Used as primary control for bank and horizontal movement.

- D -     Back to top

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.

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.

DECK: The helibase operational area that includes the touchdown pad, safety circle, hover lanes, and external cargo transport area.

DECK COORDINATOR: Person responsible to the helibase manager for coordinating the movement of personnel and cargo at the helibase landing area.

DEEP-SEATED FIRE: A fire burning far below the surface in duff, mulch, peat, or other combustibles as contrasted with a surface fire. A fire that has gained headway and built up heat in a structure so as to require greater cooling for extinguishment.

DEEPENING: 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 windflow around the low).

DEGRADATION: 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). (see also AERIAL IGNITION DEVICE, HELITORCH, PING-PONG BALL SYSTEM, PLASTIC SPHERE DISPENSER)

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.

DEMOBILIZATION: 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.

DENSITY ALTITUDE: Pressure altitude corrected for temperature deviations from standard atmosphere. Used as an index to aircraft performance characteristics such as take-off distance and rate of climb. Density altitude bears the same relation to pressure altitude as true altitude does to indicated altitude.

DEPLOYMENT ZONE: Used when fire conditions are such that escape routes and safety zones have been compromised. Deployment zones are last ditch areas where fire shelters must be deployed to ensure firefighter survival due to the available space and/or fire behavior conditions at the deployment zone location. (see also SAFETY ZONE)

DEPTH OF BURN (DOB): The reduction in forest floor thickness due to consumption by fire.

DEPUTY: 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.

DESIGNATED CONTROL BURN (DESCON): Management system used in the Southern Region of the Forest Service which permits designated personnel to accept specific wildfires as prescribed fires and handle them accordingly. Only fires burning within a specified range of environmental and fuel conditions and contributing to land management goals may be accepted as DESCON fires.

DESICCANT: 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.

DESIRED PLANT COMMUNITY: A plant community which produces the kind, proportion, and amount of vegetation necessary for meeting or exceeding the land use plant goals and activity plan objectives established for the site.

DETECTION: The act or system of discovering and locating fires. (Syn. FIRE DETECTION) 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.

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 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.

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.

DILUTION: 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 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. (Syn. PROTECTION AREA)
DIRECTOR: The ICS title for an individual responsible for supervision of a branch.

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.

DISPATCH: The implementation of a command decision to move a resource or resources from one place to another.

DISPATCHER: A person who receives reports of discovery and status of fires, confirms their locations, takes action promptly to provide people and equipment likely to be needed for control efforts. (see also AGENCY DISPATCHER)

DISPATCH CENTER: A facility from which resources are assigned to an incident.

DISPERSION: The decrease in concentration of airborne pollutants as they spread throughout an increasing volume of atmosphere.

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.

DISTURBANCE: A weather system usually associated with clouds, rain and/or wind.

DIURNAL: 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.

DIVERGENCE: The expansion or spreading out of a horizontal wind field. Generally associated with high pressure and light winds.

DIVISION: 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. A division is located within the ICS organization between the branch and the task force/strike team. (see also GROUP)

DOCUMENTATION UNIT: Functional unit within the planning section responsible for collecting, recording and safeguarding all documents relevant to the incident.

DOODLEBUG (stone boat): Water tank trailer of 200 or 250 gallon (757 or 943 L) capacity. Equipped with suction hose, strainer, and valves for filling backpack cans. Sometimes fitted with a pump making it a self-contained fire unit. When so equipped it can be pulled by pickup or tractor.

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.

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.

DOWNLOADING (AVIATION): A calculated reduction in payload to provide a margin of safety.

DOZER: Any tracked vehicle with a front mounted blade used for exposing mineral soil. (see also TRACTOR)

DOZER COMPANY: A resource that includes a dozer, its transportation unit and a standard complement of personnel for its operation.

DOZER: 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.

DRAFT: 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.

DRIFT: 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: The number of wheels that are powered by all of the vehicle's drive axles. Dual tires are considered as single wheels. This information 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.

DRIZZLE: Precipitation composed exclusively of water drops smaller than 0.02 inches (0.5 mm) in diameter.

DROP CONFIGURATION: The type of air drop selected to cover the target. Terms which specify drop configuration include: Salvo-drop the entire load, Trail- drop tanks in sequence, Single or Double Door-drop a partial load.

DROP PASS: Indicates that the air tanker 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. (Syn. PATTERN)

DROP ZONE (DZ): Target area for airtankers, helitankers, cargo dropping. (see also TARGET)

DROUGHT: 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. (see also KEETCH-BYRAM DROUGHT INDEX)

DRUM LIFTER: Device used to transport a 55-gallon drum (208 L) via sling on a helicopter.

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 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: 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); also 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 lead plane 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. (see also WET STORAGE)

DRY ADIABATIC LAPSE RATE: The rate of decrease of temperature with height of a parcel of dry air lifted a diabatically through an atmosphere in hydrostatic equilibrium. Numerically equal to 9.767° C per km or about 5.4° F per thousand feet.

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.

DUFF: The layer of decomposing organic materials lying below the litter layer of freshly fallen twigs, needles, and leaves and immediately above the mineral soil. (see also HUMUS, LITTER)

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.

- E -     Back to top