6 Minutes for Safety (6MFS) A daily safety briefing for wildland fire that focuses on high risk events found within a firefighter's scope of work that are performed on an infrequent basis. Also know as Six Minutes for Safety. View the Six Minutes for Safety website at https://www.nwcg.gov/committee/6mfs

Abort To jettison a load of water or retardant from an aircraft, or terminate a preplanned aircraft maneuver.

Abort Area A designated area where unused quantities of water or fire retardant may be jettisoned, usually to permit an airtanker to land with less than a full load.

Above Ground Level (AGL) Term frequently used in aviation operations, usually in connection with a stated altitude.

Absolute Humidity According to the American Meteorological Society, (Also called Vapor Density.) In a system of moist air, the ratio of the mass of water vapor present to the volume occupied by the mixture; that is, the density of the water vapor component. Source: http://glossary.ametsoc.org/wiki/Absolute_humidity

Absorption Act of soaking up and retaining a gas in liquid or in a solid; also retention of radiant energy.

Accelerant Material (usually a flammable liquid) used to initiate or increase the spread of a fire.

Acceptable Fire Risk The potential fire loss a community is willing to accept rather than provide resources to reduce such losses.

Accessibility Burn The burning of understory prior to the sale of forest products to improve the efficiency of timber marking and harvesting.

Accounting Code Agency-specific accounting data. Each agency assigns a specific accounting code to an incident.

Accrual Reports Cost reports utilized for financial obligation purposes.

Action Plan Any tactical plan developed by any element of ICS in support of the incident action plan. see also: Incident Action Plan



Active Crown Fire A fire in which a solid flame develops in the crowns of trees, but the surface and crown phases advance as a linked unit dependent on each other.

Activity Fuels Fuels resulting from, or altered by, forestry practices such as timber harvest or thinning, as opposed to naturally created fuels. see also: Logging Debris; Natural Fuels



Actual Time En Route (ATE) Term used in flight planning/following to document actual time spent flying between points.

Actual Time of Arrival (ATA) Term used in flight planning/following to document time of arrival at a point.

Actual Time of Departure (ATD) Term used in flight planning/following to document time of departure from a point.

Adapter A device for connecting hoses of the same size with non-matching hose threads, or connecting a threaded coupling to a quick-connect coupling. see also: Coupling



Adiabatic Process According to the American Meteorological Society, a process in which a system does not interact with its surroundings by virtue of a temperature difference between them. In an adiabatic process any change in internal energy (for a system of fixed mass) is solely a consequence of working. For an ideal gas and for most atmospheric systems, compression results in warming, expansion results in cooling. Source: http://glossary.ametsoc.org/wiki/Adiabatic_process.

Adjective Rating A public information description of the relative severity of the current fire danger situation.

Administrative Payment Team (APT) A team that supports incident agencies by processing payments for resources. Resources may include emergency equipment, casuals, local vendors for supplies, etc.

Administrative Representative (AR) Individual responsible for incident agency business management functions, such as personnel, procurement, fiscal, etc.

Administrative Workweek Period of seven consecutive calendar days designated in advance by the head of a department (5 U.S.C. 6101(a)).

Administratively Determined (AD) A person hired and compensated under the Pay Plan for Emergency Workers. synonym: Casual see also: Emergency Firefighter



Admission Oral or written statement tending to link its maker to involvement in a particular crime.

Advanced Life Support (ALS) Advanced life support skills performed by an EMS practitioner or service, e.g. intravenous fluids and drug administration.

Advancing a Line Moving a hose lay toward a specified area from the point where the hose-carrying apparatus has stopped.

Advancing Fire That portion of the fire with rapid fire spread with higher intensity which is normally burning with the wind and/or up slope. Also called: forward fire, or a run. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412. synonym: Head Fire



Advancing Front Combustion Stage The period of combustion when a fire is spreading, usually accompanied by flaming combustion that releases heat to sustain the convection column.

Advection According to the American Meteorological Society, the process of transport of an atmospheric property solely by the mass motion of the atmosphere; also the rate of change of the value of the advected property at a given point. Source: http://glossary.ametsoc.org/wiki/Advection.

Adze Hoe A fire-trenching or digging tool having a sharp, tempered blade, which is useful for heavy grubbing, trenching, and light cutting.

Aerial Detection A system for, or the act of discovering, locating, and reporting fires from aircraft.

Aerial Fuels Standing and supported live and dead combustibles not in direct contact with the ground and consisting mainly of foliage, twigs, branches, stems, cones, bark, and vines. see also: Draped Fuels



Aerial Ignition Ignition of fuels by dropping incendiary devices or materials from aircraft.

Aerial Reconnaissance Use of aircraft for detecting and observing fire behavior, values-at-risk, suppression activity, and other critical factors to facilitate command decisions on strategy and tactics needed for fire suppression.

Aerial Torch An ignition device suspended under a helicopter, capable of dispensing ignited fuel to the ground for assistance in burning out or backfiring.

Affidavit A statement of declaration in writing and affirmed before an official with authority to administer an oath; a statement of declaration alleging fact to support the issuance of a search or arrest warrant.

After Action Review (AAR) A structured review or de-brief process of an event, focused on performance standards, that enables participants to discover for themselves what happened, why it happened, and how to sustain strengths and improve on weaknesses. After action reviews, informal or formal, follow the same general format, involve the exchange of ideas and observations, and focus on improving performance.

Agency An administrative division of a government with a specific function, or a non-governmental organization (e.g., private contractor, business, etc.) that offers a particular kind of assistance. A federal, tribal, state or local agency that has direct fire management or land management responsibilities or that has programs and activities that support fire management activities. see also: Assisting Agency; Cooperating Agency; Supporting Agency



Agency Administrator The official responsible for the management of a geographic unit or functional area. The managing officer of an agency, division thereof, or jurisdiction having statutory responsibility for incident mitigation and management. Examples: NPS Park Superintendent, BIA Agency Superintendent, USFS Forest Supervisor, BLM District Manager, FWS Refuge Manager, State Forest Officer, Tribal Chairperson, Fire Chief, Police Chief. see also: Line Officer



Agency Certification The process whereby the employing agency or contractor documents that the individual is fully qualified to perform duties and responsibilities for a specified position.

Agency Dispatch The agency or jurisdictional facility from which resources are allocated to incidents.

Agency Dispatcher A person working within an agency organization who processes resources to and from incidents. see also: Dispatcher



Agency Pilot A federal employee pilot or pilot contracted by a federal agency to fly agency, contracted or leased aircraft. This does not include pilots employed by an aircraft vendor as part of an aircraft services contract, such as airtanker contracts, helicopter contracts or other aircraft contracts.

Agency Specific Costs Costs incurred by an agency that address the sole concern of only the agency or are not incurred with mutual benefit. Agency specific costs are not shared.

Agency/Area Coordination Center A facility which serves as a central point for one or more agencies to use in processing information and resource requests. It may also serve as a dispatch center for one of the agencies.

Air Ambulance A rotary wing aircraft configured, staffed and equipped to respond, care for and transport a patient(s) and approved/licensed by a state to do so. An air ambulance is sometimes referred to as a medevac.

Air Attack The deployment of fixed-wing or rotary aircraft on a wildland fire, to drop retardant or extinguishing agents, shuttle and deploy crews and supplies, or perform aerial reconnaissance of the overall fire situation.

Air Attack Base Permanent facility at which aircraft are stationed for use in air attack operations. see also: Reload Base



Air Cargo All items for transport and delivery by aircraft.

Air Contaminant An airborne dust, fume, gas, mist, odor, smoke, vapor, soot, pollen, carbon, acid or particulate matter or any combination thereof. see also: Air Pollution



Air Crew Member Additional crew member required for accomplishment of the mission such as flight attendant, smokejumper/rappel spotter, cargo loadmaster, helicopter manager, etc. These positions usually do not require any Airman Certificate(s) or a flight physical. Referred to as a Qualified Non-Crew Member in the CFR. Source: NWCG Standards for Helicopter Operations, PMS 510.

Air Guard A common VHF-FM frequency used by natural resource agency aircraft for emergency radio transmissions. Also called national air safety guard frequency.

Air Mass According to the American Meteorological Society, a widespread body of air that is approximately homogeneous in its horizontal extent, particularly with reference to temperature and moisture distribution; in addition, the vertical temperature and moisture variations are approximately the same over its horizontal extent. The properties of the air mass are established while that air was situated over a particular region of the earth's surface. Source: http://glossary.ametsoc.org/wiki/Air_mass.

Air Pack Portable air (not oxygen) tanks with regulators which allow firefighters to breathe while in toxic smoke conditions. Usually rated for 30 minutes of service. Used primarily on fires involving structures or hazardous materials. synonym: Self-Contained Breathing Apparatus 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. see also: Air Contaminant



Air Pollution Alert A statement issued by an Air Quality Regulatory Agency due to high measured concentrations of pollutants. The alert remains in effect until monitoring shows a decrease in pollutant levels. Should conditions worsen, air pollution warnings and emergencies may be issued. At each stage (alert, warning and emergency) additional emission restrictions are put into effect so as to not intensify the situation. Essentially, at the emergency level all industrial activities and auto usage stop.

Air Quality "The composition of air with respect to quantities of pollution therein; used most frequently in connection with ""standards"" of maximum acceptable pollutant concentrations. Used instead of ""air pollution"" when referring to programs. "

Air Quality Model Mathematical or quantitative representation or simulation of air quality processes; e.g., emission models, receptor models, or air quality dispersion models.

Air Stagnation Advisory (ASA) (Also called Air Quality Alerts.) A statement issued by a National Weather Service forecast office when atmospheric conditions are stable enough such that the potential exists for air pollutants to accumulate in a given area. The statement is initially issued when conditions are expected to last for at least 36 hours.

Aircraft Accident An unplanned event that does substantial damage or causes serious injuries when associated with the operation of applicable aircraft. Event occurs between the time engine(s) is (are) started or rotors turning for the purpose of commencing flight, until the aircraft comes to rest with engines and propellers or rotors stopped, the brakes set or wheel chocks in place, and all persons have disembarked.

Aircraft Data Card Card or documentation required to be on board the aircraft which approves use and indicates specific types of use.

That area on the surface of the earth, runway, or ramp that is covered by the tread of the aircraft tire while the aircraft is motionless. Also called wheel loading.

Aircraft Ground Mishap An aircraft mishap in which there is no intent to fly. However, the power plants and/or rotors are in operation and damage is incurred requiring replacement or repair of rotors, propellers, wheels, tires, wing tips, flaps, etc., or injury is incurred requiring first-aid or medical attention.

Aircraft Incident An unplanned event that results in damage which is less than serious aircraft incident criteria, or injuries not requiring medical attention. see also: Serious Aircraft Incident



Aircraft Network (AirNet) Applies to radio frequencies primarily used for air operations.

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

Alidade A sighting device used by lookouts to determine the horizontal bearing and sometimes the vertical angle of a fire from a lookout. synonym: Osborne Firefinder



All Hazard Incident An incident, natural or human-caused, that requires an organized response by a public, private, and/or governmental entity to protect life, public health and safety, values to be protected, and to minimize any disruption of governmental, social, and economic services. One or more kinds of incident (fire, flood, mass casualty, search, rescue, evacuation, etc.) may occur simultaneously as part of an all hazard incident response. see also: Incident; Values To Be Protected



All Hazards Meteorological Response System (AMRS) A mobile weather data collection and forecasting system consisting of a communications module, weather observing module, and data interigation module. Used by incident meteorologists on an incident. Source: NWS policy 10-402 http://www.nws.noaa.gov/directives/sym/pd01004002curr.pdf see also: Incident Meteorologist



All Terrain Vehicle (ATV) Any motorized vehicle designed for or capable of cross-country travel on or immediately over land, water, sand, snow, ice, marsh, swampland, or other terrain. synonym: Off-road Vehicle



Alligatoring Char patterns formed on paint or burned wood remains, usually in the shape of blisters. see also: Depth of Char Indicators



Allowable Payload The amount of weight that is available for passengers and/or cargo. On the load calculation form it is the operating weight subtracted from the selected weight. see also: Operating Weight



Altimeter Setting The barometric pressure reading used to adjust a pressure altimeter for variations in existing atmospheric pressure or to the standard altimeter setting (29.92) inches.

Ambient Air According to the American Meteorological Society, background, environmental, or surrounding air. Source: http://glossary.ametsoc.org/wiki/Ambient_air

Ambulance A ground transport vehicle configured, equipped and staffed to respond, care for and transport a patient(s) and approved by a state to do. see also: Air Ambulance



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 According to the American Meteorological Society, the general name for instruments designed to measure total wind speed. Source: http://glossary.ametsoc.org/wiki/Anemometer

Annual Certification Annual review by an employing agency of an individual's position qualifications and documentation certifying that the individual is fully qualified to perform duties and responsibilities for a specified position. Annual certification is based on established performance standards and agency specific requirements.

Annual Operating Plan (for Fire Weather) (AOP) A procedural guide which describes fire meteorological services provided within the Geographic Area of responsibility, including the National Interagency Fire Center. The guide is based on the National Interagency Agreement and applicable Geographic Area Memorandum of Agreement.

Annual Plant A plant that lives for one growing season, starting from a seed each year.

Anticyclone According to the American Meteorological Society, an atmospheric anticyclonic circulation, a closed circulation. The wind in an anticyclone is in the clockwise direction in the Northern Hemisphere. Source: http://glossary.ametsoc.org/wiki/Anticyclone see also: Surface High



Apparatus A motor-driven vehicle, or group of vehicles, designed and constructed for the purpose of fighting fires. May be of different types such as engines, water tenders, ladder trucks, etc.

Approved In fire service terminology, that which is inspected and listed by recognized fire-testing 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. see also: Nomex ®



Area Command An organization established to: 1) oversee the management of multiple incidents that are each being handled by an incident management team (IMT) organization; or 2) to oversee the management of a very large incident that has multiple IMTs assigned to it. Area Command has the responsibility to set overall strategy and priorities, allocate critical resources based on priorities, ensure that incidents are properly managed, and that objectives are met and strategies followed.

Area Ignition Ignition of several individual fires throughout an area, either simultaneously or in rapid succession, and so spaced that they add to and influence the main body of the fire to produce a hot, fast-spreading fire condition. Also called simultaneous ignition.

Area of Influence Delineated area surrounding a base which can be reached first by the ground or air attack units assigned to the base. Also called zone of influence.

Area Source A source category of air pollution that generally extends over a large area. Prescribed burning, field burning, home heating, and open burning are examples of area sources.

Armed A term used to indicate that the airtanker dropping mechanism is set to allow a programmed release of part or all of the load of fire retardant.

Arrest The taking or keeping of a person in custody by legal authority, especially in response to a criminal charge.

Arson At common law, the malicious and willful burning of another?s dwelling, outhouse or parcel; by most modern statutes, the intentional and wrongful burning of someone else's, or one's own, property. Frequently requires proof of malicious or wrongful intent.

Arson Fire A fire that is intentional and wrongfully set to burn one's own or someone else's property.

Arson Task Force Group of individuals convened to analyze, investigate and solve arson problems in a particular region.

Arsonist One who commits arson.

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.

Assessment A fire weather fire danger product based on a thorough evaluation of all pertinent sources of meteorological, fire danger and resource information. The evaluation and interpretation of measurements, intelligence, and other information to provide a basis for decision-making.

Assignments Tasks given to resources to perform within a given operational period, based upon tactical objectives in the incident action plan.

Assistant Term used as a title for subordinates of the command staff positions. In some cases, assistants are also assigned to unit leader positions in the planning, logistics, and finance/administration sections. Qualifications, technical capability, and responsibility of assistants are normally less than those of the person holding the primary position.

Assumption Acceptance of information as true without proof or demonstration.

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

Atmospheric Inversion According to the American Meteorological Society, a departure from the usual decrease or increase with altitude of the value of an atmospheric property; also, the layer through which this departure occurs (the "inversion layer"), or the lowest altitude at which the departure is found ("the base of the inversion"). In fire management usage, nearly always refers to an increase in temperature with increasing height. Source: http://glossary.ametsoc.org/wiki/Inversion see also: Atmospheric Stability; Inversion; Stable Layer of Air



Atmospheric Pressure According to the American Meteorological Society, (also called barometric pressure), the net force per unit area exerted by the atmosphere as a consequence of gravitational attraction exerted upon the column of air lying directly above the point in question. Atmospheric pressure is independent of the orientation of the surface on which it acts. Source: http://glossary.ametsoc.org/wiki/Atmospheric_pressure see also: Barometric Pressure



Atmospheric Stability According to the American Meteorological Society, (also called static stability), the ability of the atmosphere at rest to become turbulent or laminar due to the effects of buoyancy. Air tending to become or remain turbulent is said to be statically unstable; one tending to become or remain laminar is statically stable; and one on the borderline between the two (which might remain laminar or turbulent depending on its history) is statically neutral. Source: http://glossary.ametsoc.org/wiki/Static_stability see also: Atmospheric Inversion; Inversion; 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. An area may be in attainment for one or more pollutants but be in nonattainment for one or more other pollutants.

Automatic Weather Station (AWS) A non-GOES telemetered weather station that provides hourly observations to a local database.

Automatically Regulated A proportioning method or device that readily adjusts to changes in water flow and or pressure to maintain a desired mix ratio.

Autorotation A helicopter flight condition in which the lifting rotor is driven entirely by action of air when the helicopter is in motion.

Auxiliary Pump A secondary pump on an engine in addition to the main pump. Usually of small capacity.

Available Fuel That portion of the total fuel that would actually burn under various environmental conditions.

Average Annual Precipitation The expected amount of annual rainfall. Average annual precipitation is an important component to determining the Keech-Bryam Drought Index (KBDI).

Average Relative Humidity Part of the National Fire Danger Rating System (NFDRS). The mathematical average of the maximum and minimum relative humidities measured at a fire weather station from one basic observation time to the next.

Average Temperature According to the American Meteorological Society, (also called the mean temperature), the average temperature of the air as indicated by a properly exposed thermometer during a given time period, usually a day, a month, or a year. Source: http://glossary.ametsoc.org/wiki/Mean_temperature

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

Awareness The continual process of collecting, analyzing, and disseminating intelligence, information, and knowledge to allow organizations and individuals to anticipate requirements and to react effectively and safely.

Azimuth (Measurement Technique) Horizontal angle or bearing of a point measured clockwise from true (astronomic) north. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412. Definition Extension: This method is useful for short distance measurements that do not have to deal with many obstacles and may be difficult on steep ground.



Azimuth Circle A circle graduated in 360 degrees in a clockwise direction from true (astronomic) north.

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 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). synonym: Burning Torch see also: Drip Torch; Flame Thrower



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. That portion of the fire with slower rates of fire spread and lower intensity normally moving into the wind and/or down slope. Also called: heel fire. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.

Backing Wind According to the American Meteorological Society, in the Northern Hemisphere, a wind that rotates in the counterclockwise direction with increasing height. In fire management usage, in the Northern Hemisphere, a wind that rotates in the counterclockwise direction over a given time period (normally a few hours). Source: http://glossary.ametsoc.org/wiki/Backing_wind

Backpack Pump A portable sprayer with hand-pump, fed from a liquid filled container fitted with straps, used mainly in fire and pest control. 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 According to the American Meteorological Society, an instrument for measuring atmospheric pressure. Source: http://glossary.ametsoc.org/wiki/Barometer

Barometric Pressure Atmospheric pressure corrected for elevation. see also: Atmospheric Pressure



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

Base 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. 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 Hours The number of hours in a daily tour of duty.

Base Observation Time Part of the National Fire Danger Rating System (NFDRS). The time established to take the fire danger observations. It should be at the time of day when the fire danger is normally the highest. The usually agreed upon time is 1:00 pm standard time. This allows time to transmit observations and prepare forecasts.

Base Station A fixed central radio dispatching station controlling movements of one or more mobile units.

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.

Basic Life Support (BLS) Basic life support skills performed by an EMS practitioner or service, e.g. splinting, bandaging, oxygen administration, use of the AED.

Basic Workweek Refers to the scheduled workweek of the employee (individual) at the home unit.

Batch Mix Manually adding and mixing a concentrated chemical, such as liquid foam, or powdered or liquid retardant with water, or gelling agents with fuel, into solution in a tank or container.

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 According to the American Meteorological Society, a system of estimating and reporting wind speeds using a numerical scale ranging from 0 (calm) to 12 (hurricane). Source: http://glossary.ametsoc.org/wiki/Beaufort_wind_scale

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

Behavior An observable activity or action demonstrated by an individual in a particular context. see also: Competency



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.

Benefits Something that represents, promotes or enhances a desired outcome, being of positive value and contributing to the attainment of organizational goals. Benefits represent one end of the spectrum of outcomes from fire, with the opposite end being harm, loss or damage. see also: Fire Benefits



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) An emission limitation action based on the maximum degree of emission reduction (considering energy, environmental, and economic impacts) achievable through application of production processes and available methods, systems, and techniques. see also: Reasonably Available Control Measures



Billable/Reimbursable Costs Those agency costs that are billable and/or reimbursable as defined by the master or individual cost share agreement.

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.

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; 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. The board reviews the results in order to identify reasons for both good and poor action and to recommend or prescribe ways and means of doing an effective and efficient job. Reviews the results of a safety/accident investigation.

Boiling Liquid Expanding Vapor Explosion (BLEVE) The failure of a closed container as a result of overpressurization caused by an external heat source. 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 mop up term. To "bone yard" a fire means to systematically work the entire area, scraping embers off remaining fuel, feeling for heat with the hands, and piling unburned materials in areas cleared to mineral soil. 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. see also: Hose Reel



Boundary Conditions The temperature and relative humidity of the boundary layer.

Boundary Layer According to the American Meteorological Society, the layer of air near a boundary that is affected by friction against that boundary surface, and possibly by transport of heat and other variables across that surface. According to the American Meteorological Society, (also called the atmospheric boundary layer) the bottom layer of the troposhpere that is in contact with the surface of the earth. It is often turbulent and is capped by a statically stable layer of air or temperature inversion. Source: http://glossary.ametsoc.org/wiki/Boundary_layer

Boundary Value The equilibrium moisture content (EMC) commensurate with the boundary conditions and precipitation events of the preceding 24 hours.

Bowles Bag A neoprene tank designed for attachment to the landing skid frame of a helicopter. It has a capacity of 80 to 100 gallons (303 to 378 liters) of water or retardant.

Box Canyon A steep-sided, dead end canyon.

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.

Breakover A fire edge that crosses a control line or natural barrier intended to confine the fire. synonym: Slopover



British Thermal Unit (Btu) Amount of heat required to raise 1 pound of water 1 degree Fahrenheit (from 59.50 to 60.50 F), measured at standard atmospheric pressure.

Broadcast Burning Prescribed burning activity where fire is applied generally to most or all of an area within well defined boundaries for reduction of fuel hazard, as a resource management treatment, or both.

Brown and Burn Application of herbicide to desiccate living vegetation prior to burning.

Brownspot Control Prescribed fire to control fungal infection (brown spot disease) of longleaf pine (Pinus palustris) in the "grass" (small seedling) stage.

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 The cumulative effects of long-term drying on current fire danger. The increase in strength of a fire management organization. The accelerated spreading of a fire with time. 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. see also: Compactness



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. synonym: Move Up Method



Burn An area burned over by wildland fire. A reference to a working fire. An injury to flesh caused by a cauterizing agent, heat from a fire, or a heated object. First Degree Burn: A burn which causes only pain, redness, and swelling.

Second Degree Burn: A burn in which the skin is blistered.

Third Degree Burn: A flesh burn in which charring occurs. To be on fire. To consume fuel during rapid combustion. A fire in progress or under investigation.

Burn Block A discrete area within a larger prescribed or fire use project.

Burn Out Setting fire inside a control line to consume fuel between the edge of the fire and the control line. 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.

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. Definitions are scale-dependent: (1) They can be used to trace a fire's origin; (2) They are influenced by severity and intensity within a stand; (3) They describe the landscape mosaic. Apparent and obvious design of burned material and the burning path from the area of origin.

Burn Severity A qualitative assessment of the heat pulse directed toward the ground during a fire. Burn severity relates to soil heating, large fuel and duff consumption, consumption of the litter and organic layer beneath trees and isolated shrubs, and mortality of buried plant parts.

Burned Area Emergency Response (BAER) Team BAER teams are formed to analyze post-fire conditions and to take immediate emergency stabilization action to prevent loss of life and property and critical and natural resources. It is the Agency Administrator’s responsibility to order or designate a BAER Team.

Burned Area Rehabilitation The post-fire activities prescribed and implemented to rehabilitate and restore fire damaged lands. see also: Rehabilitation



Burning Decomposition of material by the application of heat and oxidation. Also applied to propellants and other pyrotechnic mixtures, though the proper term there is "reacting". Also often an element of the crime of arson.

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

Burning Conditions The state of the combined factors of the environment that affect fire behavior in a specified fuel type.

Burning Index An estimate of the potential difficulty of fire containment as it relates to the flame length 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 Index Meter A device used to determine the burning index for different combinations of burning index factors.

Burning Out Setting fire inside a control line to consume fuel located between the edge of the fire and the control line.

Burning Period That part of each 24-hour period when fires spread most rapidly; typically from 10:00 AM to sundown.

Burning Priority Rating System of rating slash to indicate the treatment objective, whether or not burning is required to meet that objective, the fuel treatment necessary to achieve successful burning, and the time of year burning should occur.

Burning Rate Rate at which a propellant and other combustibles burn.

Burning Rotation The planned number of years between prescribed fires on a specified area.

Burning Torch A flame generating device (e.g., a fount containing diesel oil or kerosene and a wick, or a backpack pump serving a flame-jet). synonym: Backfire Torch see also: Drip Torch; Flame Thrower



Burnover An event in which a fire moves through a location or overtakes personnel or equipment where there is no opportunity to utilize escape routes and safety zones, often resulting in personal injury or equipment damage.

Buying Team A team that supports one or more incidents and is authorized to procure a wide range of services, supplies, and land and equipment rentals. In addition, the Buying Team Leader has the responsibility of coordinating property accountability with the Supply Unit Leader.

Buys Ballots Law According to the American Meteorological Society, a law describing the relationship of the horizontal wind direction in the atmosphere to the pressure distribution; if one stands with the back to the wind, the pressure to the left is lower than to the right in the Northern Hemisphere. Source: http://glossary.ametsoc.org/wiki/Buys_ballot%27s_law

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



Candling The burning of the foliage of a single tree or a small group of trees, from the bottom up. synonym: Torching



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

Carbon Dioxide (CO2) A colorless, odorless, nonpoisonous gas, which results from fuel combustion and is normally a part of the ambient air.

Carbon Monoxide (CO) A colorless, odorless, poisonous gas produced by incomplete fuel combustion.

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.

Casual A person hired and compensated under the Pay Plan for Emergency Workers. synonym: Administratively Determined 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 re-established the normal cross-section. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.

Ceiling According to the American Meteorological Society, the height ascribed to the lowest layer of clouds or obscuring phenomena when it is reported as broken, overcast, or obscuration and not classified "thin" or "partial." The ceiling is termed unlimited when the foregoing conditions are not satisfied. Source: http://glossary.ametsoc.org/wiki/Ceiling

Celsius According to the American Meteorological Society, same as centigrade temperature scale, by convention. Centigrade temperature scale is a temperature scale with the ice point of water at 0 degrees and the boiling point at 100 degrees. Source: http://glossary.ametsoc.org/wiki/Centigrade_temperature_scale

Center Firing Method of broadcast burning in which fire is ignited in the center of the area to create a strong draft; additional fires are then ignited progressively nearer the outer control lines (sometimes in one step) as indraft increases so as to draw the flames and smoke toward the center.

Centrifugal Pump Pump which expels water by centrifugal force through the ports of a circular impeller rotating at high speed. With this type of pump, the discharge line may be shut off while the pump is running without damaging the pump or hose.

Certifying Official The agency official at the home unit who is responsible for authorizing and granting position certification per agency policy. The agency official is responsible for completing the agency certification block located on the inside front cover of a Position Task Book. see also: Agency Certification; Home Unit; Position Task Book



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 Carbonaceous material formed by incomplete combustion of an organic material, most commonly wood; remains of burned materials. In fire simulation, a darkened area within the fire perimeter; usually indicates fire has already passed through; usually created by an opaque material blocking out a selected portion of basic scene illumination.

Char Height The vertical distance above ground scorched or blackened on a tree bole.

Charged Line Hose filled with water under pressure and ready to use. synonym: Live Line see also: Live Reel



Chase Truck Vehicle that carries crew gear, supplies, and operational equipment for initial/extended attack.

Check Line A temporary fireline constructed at right angles to the control line and used to hold a backfire in check as a means of regulating the heat or intensity of the backfire.

Check Valve A valve that permits flow of liquid through a hose or pipe in one direction but prevents a return flow. Uses include the prevention of backflow on uphill hose lays, loss of prime with centrifugal pumps and chemical contamination in fire chemical mixing systems.

Check-in The process whereby resources first report to an incident. Check-in locations include incident command post (ICP), base or camps, staging areas, helibases, or direct to a tactical assignment. see also: Reporting Locations



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.

Circumstantial Evidence Testimony or information not based on actual personal knowledge or observation, but dependent on inference of other facts or experience. For example, testimony that defendant?s cigarette lighter was found in ashes of a fire.

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

Claim A written demand for a specific amount of money or other objects of value, other than ordinary obligations incurred for services, supplies, or things.

Claimant An individual, partnership, association, corporation, country, the federal government, state, or other political subdivision asserting a right, demand, or claim against another entity.

Class A Foam Foam intended for use on Class A or woody fuels; made from hydrocarbon-based surfactant, therefore lacking the strong filming properties of Class B foam, but possessing excellent wetting properties.

Class B Foam Foam designed for use on Class B or flammable liquid fires; made from fluorocarbon-based surfactants, therefore capable of strong filming action, but incapable of efficient wetting of Class A fuels.

Class I Areas (Air Quality) Geographic areas designed by the Clean Air Act subject to the most stringent restrictions on allowable increment of air quality deterioration. Class I areas include Forest Service wildernesses and nation memorial parks over 5,000 acres, National Parks exceeding 6,000 acres, international parks, as well as other designated lands.

Class II Areas (Air Quality) All areas of the country not designated Class I, including everything from non-Class I areas to urban areas. A greater amount of air pollution can be added to these areas than Class I.

Clean Air Act A federal law enacted to ensure that air quality standards are attained and maintained. Initially passed by Congress in 1963, it has been amended several times.

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

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

Climate Class In NFDRS, one of four classifications of general climate of an area.

Climatological Breakpoint Points on the cumulative distribution of one fire weather/fire danger index without regard to associated fire occurrence/business.

Clock Method Means of establishing a flight path to a target on a fire by referring to clock directions from the aircraft's present location, with the nose of the aircraft pointing at 12:00.

Closed Area An area in which specified activities or entry are temporarily restricted to reduce risk of human-caused fires or to mitigate the risk to human health or safety by potential or on-going wildland fires.

Closure An administrative action limiting or prohibiting access to a specific geographic or jurisdictional area for the purposes of reducing wildfire or the risk it poses to life, property, and/or resources. Example of use: "Pursuant to 36 C.F.R. 261.50 (a) and (b), it is hereby ordered that the prohibitions hereinafter set forth apply to the general forest area of the Ozark-St. Francis National Forests until further notice." see also: Restrictions



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."

Co-op Fire Refers to federal, state, and local cooperative fire programs.

Cold Front The leading edge of a relatively cold air mass which displaces warmer air, causing it to rise. If the lifted air contains enough moisture, cloudiness, precipitation and even thunderstorms may result. As fronts move through a region, in the Northern Hemisphere, the winds at a given location will experience a marked shift in direction. Ahead of an approaching cold front, winds will usually shift gradually from southeast to south, and on to southwest. As a cold front passes, winds shift rapidly to west, then northwest. Typical cold front windspeeds range between 15 and 30 mph but can be much higher.

Cold Line Fireline that has been controlled. The fire has been mopped up for a safe distance inside the line and can be considered safe to leave unattended.

Cold Trailing A method of controlling a partly dead fire edge by carefully inspecting and feeling with the hand for heat to detect any fire, digging out every live spot, and trenching any live edge.

Collective Control Controls the pitch angle of the main (helicopter) rotor blades. Used as primary altitude control.

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

Combination Nozzle A nozzle is designed to provide either a solid stream or a fixed spray pattern suitable for applying water, wet water or foam solution. Also called: Adjustable Fog Nozzle.

Combination Nozzle Tip Two attached straight stream nozzle tips of different orifice size used to increase or restrict water flow.

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 Climate The working environment within the influence of a particular leader or chain of command. The command climate is based on the subordinates' understanding of how they are expected to perform, how they are treated, and how they must conform to the leader's style.

Command Presence How leaders present themselves to others. The personal attributes and traits that determine whether leaders are worthy of trust and respect from their subordinates.

Command Staff The command staff consists of the information officer, safety officer and liaison officer. They report directly to the incident commander and may have an assistant or assistants, as needed.

Communications Unit An organizational unit in the Logistics Section responsible for providing and maintaining communication services at an incident. May also be a facility (e.g., a trailer or mobile van) used to provide the major part of an incident communications center.

Community Wildfire Protection Plan (CWPP) A plan developed in the collaborative framework established by the Wildland Fire Leadership Council and agreed to by state, tribal, and local government, local fire department, other stakeholders and federal land management agencies managing land in the vicinity of the planning area. A Community Wildfire Protection Plan (CWPP) identifies and prioritizes areas for hazardous fuel reduction treatments and recommends the types and methods of treatment on Federal and non-Federal land that will protect one or more at-risk communities and essential infrastructure and recommends measures to reduce structural ignitability throughout the at-risk community. A CWPP may address issues such as wildfire response, hazard mitigation, community preparedness, or structure protection - or all of the above.

Compact A formal working agreement among agencies to obtain mutual aid.

Compactness Spacing between fuel particles. see also: Bulk Density



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

Compare and Contrast An investigative technique that involves comparing same sized indicators within an indicator category at separate locations; looking for either differences or similarities in appearance. Definition Extension: Includes the comparison of overall patterns and pattern clusters. The practice of comparing and contrasting the fire damage on different surfaces of an object that has been subjected to the oncoming fire. Definition Extension: Typically, the exposed side has more fire effects present than the contrasting protected side that normally has less fire effects visible. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.

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-for-Injury Manager Person responsible to the Compensation/Claims Unit Leader for administrative matters arising from serious injuries and fatalities occurring on the incident.

Compensation/Claims Unit Functional unit within the Finance/Administration Section responsible for the overall management and direction of all Compensation-for-Injury and Claims Specialists assigned to the incident.

Competency A broad description that groups core behaviors necessary to perform a specific function. see also: Behavior



Competent Ignition Source Any item which can produce sufficient heat over a sufficient duration of time capable of bringing forest fuels to their ignition temperature and sustain open flame combustion. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.

Compressed Air Foam Systems (CAFS) A generic term used to describe foam systems consisting of an air compressor (or air source), a water pump, and foam solution.

Computed Gross Weight Term used in calculating from performance charts the permissible helicopter payload at which a helicopter is capable of hovering in ground effect or hovering out of ground effect, based on pressure altitude and air temperature.

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

Conceptual Model A model that is a diagram or description of a set of relationships between factors that describe how a system works, such as an ecological model. see also: Model



Condensation The process by which a gas becomes a liquid.

Condition Class Depiction of the degree of departure from historical fire regimes, possibly resulting in alterations of key ecosystem components. These classes categorize and describe vegetation composition and structure conditions that currently exist inside the Fire Regime Groups. Based on the coarse-scale national data, they serve as generalized wildfire rankings. The risk of loss of key ecosystem components from wildfires increases from Condition Class 1 (lowest risk) to Condition Class 3 (highest risk). synonym: Fire Regime Current Condition Class



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 material from a region of higher temperature to a region of lower temperature.

Confine A wildfire response strategy of restricting a wildfire to a defined area, primarily using natural barriers that are expected to restrict the spread of the wildfire under the prevailing and forecasted weather conditions. Definition Extension: Some response action may be required to augment or connect natural barriers (e.g. line construction, burn-out, bucket drops, etc.). See Also: Contained; Monitoring; Point/Zone Protection; Suppression.



Confinement The strategy employed in appropriate management responses where a fire perimeter is managed by a combination of direct and indirect actions and use of natural topographic features, fuel, and weather factors.

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.

Contained The status of a wildfire suppression action signifying that a control line has been completed around the fire, and any associated spot fires, which can reasonably be expected to stop the fire's spread. see also: Containment



Containment The status of a wildfire suppression action signifying that a control line has been completed around the fire, and any associated spot fires, which can reasonably be expected to stop the fire's spread. The act of controlling hazardous spilled or leaking materials. see also: Contained

Continental Climate Climate that is characteristic of the interior of a land mass of continental size, marked by large annual diurnal and day-to-day ranges of temperature, low relative humidity and irregular precipitation.

Contingency Actions A back-up plan of action when actions described in the primary plan are no longer appropriate. Contingency actions are required to be taken when the result exceeds its intent. Actions are taken to return the project to its intended design.

Contingency Plan The portion of a prescribed fire plan, incident action plan, or implementation plan that identifies possible but unlikely events and the contingency resources needed to mitigate those events.

Contingency Resources Planned and identified fire suppression personnel and equipment that mitigate possible but unlikely events that exceed or are expected to exceed holding resource capabilities.

Contour Map A map having lines of equal elevation that represent the land surface (Topographic).

Contract Any written agreement giving one party a right, a service, or a commodity in exchange for a right, a service, or a commodity. Contracts include land use permits, purchase orders, equipment rental agreements, leases, etc.

Contracted Resource Vendor The name of the company who, through a contract, provides resources to support incident management activities. Definition extension: Must be paired with a Home Unit and Provider Unit. See also: Unit, Home; Unit, Provider



Contracting Officer (CO) Agency personnel with specific delegation of procurement authority, also known as warranted Contracting Officer.

Contracting Officer’s Technical Representative (COTR) / Contracting Officer’s Representative (COR) An individual designated by the Contracting Officer to provide technical support for the contract within specific authority and limitations as specified in the delegation. The COTR/COR must be agency certified.

Contractor Private sector personnel, vendor or business contracted to provide goods and services to a government agency.

Control Force Personnel and equipment used to control a fire.

Control Line An inclusive term for all constructed or natural barriers and treated fire edges used to control a fire.

Control Time The time a fire is declared controlled.

Controlled The completion of control line around a fire, any spot fires therefrom, and any interior islands to be saved; burned out any unburned area adjacent to the fire side of the control lines; and cool down all hotspots that are immediate threats to the control line, until the lines can reasonably be expected to hold under the foreseeable conditions.

Controlled Airspace Airspace of defined dimensions within which air traffic control service is provided to IFR and VFR flights in accordance with the airspace classification.

Controlling Nozzle Shut-off nozzle that permits the nozzle operator to open or close the nozzle or adjust the pattern of the stream.

Convection The transfer of heat by the movement of a gas or liquid; convection, conduction, and radiation are the principal means of energy transfer. 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. When this occurs in the lower atmosphere, the excess air is removed by rising air currents. Expansion of the rising air above a convergence zone results in cooling, which in turn often gives condensation (clouds) and sometimes precipitation.

Convergence Zone The area of increased flame height and fire intensity produced when two or more fire fronts burn together. In fire weather, that area where two winds come together from opposite directions and are forced upwards often creating clouds and precipitation.

Conversion Burning Burning an area where brush has excluded forest reproduction to prepare the area for tree planting.

Cooperating Agency An agency supplying assistance including but not limited to direct tactical or support functions or resources to the incident control effort (e.g. Red Cross, law enforcement agency, telephone company, etc). see also: Agency; Agency Representative; Assisting Agency; Supporting Agency



Coordinates The intersection of lines of reference, usually expressed in degrees/minutes/seconds of latitude and longitude, used to determine or report position or location.

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.

Coriolis Force An apparent force due to the rotation of the earth that causes a deflection of air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This force maximizes at the poles and is essentially zero at the equator.

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

Cost Sharing Agreements Agreements that document the financial responsibility for incident resource costs, possibly identifying requirements of other party payments.

Cost Unit Functional unit within the Finance/Administration Section responsible for collecting all cost data, performing cost effectiveness analyses, and providing cost estimates and cost saving advice.

Council Tool Long-handled combination rake and cutting tool, the blade of which is constructed of a single row of three or four sharpened teeth. Also called fire rake, council rake. 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.

Coupling Device that connects the ends of adjacent hoses or other components of hose. see also: Adapter



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.

Cover Type The designation of a vegetation complex described by dominant species, age, and form.

Coverage Level Recommended amount of aerially applied retardant keyed to the NFDRS fuel models and/or fire behavior models. Coverage level 2 represents 2 gallons of retardant per hundred square feet. Levels range from 1 to 6 for most fuel models. A coverage level of greater than 6 is for heavy fuels. The levels can be adjusted for fire behavior.

Coyote Tactics A progressive line construction duty involving self-sufficient crews which build fire line until the end of the operational period, remain at or near the point while off duty, and begin building fireline the next operational period where they left off.

Crazing Fine cracking of glass, usually from heat of fire.

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 Shuttle Transportation of fireline personnel to and/or from assigned fireline locations.

Crew Transport Any vehicle capable of transporting a specified number of personnel in a specified manner.

Criteria Pollutants Pollutants deemed most harmful to public health and welfare and that can be monitored effectively. They include carbon monoxide (CO), lead (Pb), nitrogen oxides (Nox), sulfur dioxide (SO2), ozone (O3), particulate matter (PM) of aerodynamic diameter less than or equal to 10 micrometers (PM10) and particulate matter of aerodynamic diameter less than or equal to 2.5 micrometers (PM2.5).

Critical Burnout Time Total time a fuel can burn and continue to feed energy to the base of a forward-traveling convection column.

Critical Incident Stress Debriefing (CISD) The process in which teams of professional and peer counselors provide emotional and psychological support to incident personnel who are or have been involved in a critical (highly stressful) incident.

Cross Shot Intersecting lines of sight from two points to the same object, frequently used to determine location of a fire from lookouts. Also called cross bearing.

Crown Consumption Combustion of the twigs, and needles or leaves of a tree during a fire.

Crown Cover The ground area covered by the crown of a tree as delimited by the vertical projection of its outermost perimeter.

Crown Fire A fire that advances from top to top of trees or shrubs more or less independent of a surface fire. Crown fires are sometimes classed as running or dependent to distinguish the degree of independence from the surface fire.

Crown Out A fire that rises from ground into the tree crowns and advances from tree top to tree top. To intermittently ignite tree crowns as a surface fire advances.

Crown Ratio The ratio of live crown to tree height.

Crown Scorch Browning of needles or leaves in the crown of a tree or shrub caused by heating to lethal temperature during a fire. Crown scorch may not be apparent for several weeks after the fire.

Crown Scorch Height The height above the surface of the ground to which a tree canopy is scorched.

Crowning Potential A probability that a crown fire may start, calculated from inputs of foliage moisture content and height of the lowest part of the tree crowns above the surface.

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 known as gutter trench.

Curb Weight Weight of a truck empty (without payload and driver) but ready to drive, including a full fuel tank, cooling system, crankcase, tools, spare wheel, and all other equipment specified as standard.

Cured In the 1978 version of NFDRS, the herbaceous stage when herbaceous fuel moisture falls to 30% or less.

Daily Activity Level Part of the National Fire Danger Rating System (NFDRS). In fire danger rating, a subjective estimate of the degree of activity of a potential human-caused fire source relative to that which is normally experienced. Five activity levels are defined: none, low, normal, high, and extreme.

Daily Rate Paid on a calendar day basis (0001-2400).

Damage Differential The comparative differences of damage to objects resulting from the fire’s passage. Definition Extension: One of the underlying principles that govern the interpretation of most fire pattern indicators. This principle may be observed on various surfaces of individual objects or by comparing the damage within adjoining areas of the fire. Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.

Damage Differential Indicators The amount of fire related destruction to combustible objects determined by comparing opposing sides of an object.

Dead Fuels Fuels with no living tissue in which moisture content is governed almost entirely by absorption or evaporation of atmospheric moisture (relative humidity and precipitation).

Debris Burning Fire 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). 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.

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 wind flow around the low).

Deflagration Chemical decomposition by burning material in which the reaction is less than sonic velocity, for example, low explosives. A burning with great heat and intense light.

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.

Departure from Average Greenness (DA) An NDVI-derived image of vegetation greenness compared to its average greenness for the current week of the year.

Depth of Burn (DOB) The reduction in forest floor thickness due to consumption by fire.

Depth of Char Indicators Sometimes referred to as "alligatoring", where combustible material appears to have a fissured or scaly appearance similar to an alligator's hide. Most commonly associated with finished lumber products, such as boards and fence posts.

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.

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.

Designated Dispatch Point (DDP) The address where the unit must be physically located, and dispatched from, during the mandatory availability period.

Detection The act or system of discovering and locating fires. synonym: Fire Detection see also: Discovery



Detonation An extreme rapid decomposition of a material in which the reaction is more than a sonic velocity, for example, high explosives.

Dew Point Temperature to which a specified parcel of air must cool, at constant pressure and water-vapor content, in order for saturation to occur. The dew point is always lower than the wet-bulb temperature, which is always lower than the dry-bulb temperature, except when the air is saturated and all three values are equal. Fog may form when temperature drops to equal the dew point.

Diagram A scale drawing showing information about a fire scene.

Die-Out Pattern Indicators Fingers or islands of less intensely burned areas or areas where the fire has self extinguished.

Digital Elevation Model A set of points which defines the terrain as numbers for computer applications. This data may be used to draw contours, make ortho photos, slope maps, and drive fire models.

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. see also: Dispersion



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. see also: Direct Line



Direct Line Any treatment applied directly to burning fuel such as wetting, smothering, or chemically quenching the fire or by physically separating the burning from unburned fuel. see also: Direct Attack



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. see also: Protection Area



Directional Vectors The physical characteristics of the indicators that show the direction of fire spread, i.e., advancing, backing, or lateral.

Director The ICS title for an individual responsible for supervision of a branch.

Discovery Determination that a fire exists. Location and reporting of a fire is not required as is with detection. see also: Detection



Discovery Time Elapsed time from start of fire (known or estimated) until the time of the first discovery that results directly in fire suppression action.

Discrete Frequency A separate radio frequency most commonly used in air traffic control which reduces frequency congestion by controlling the number of aircraft or other resources operating on a particular frequency.

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

Dispatch Center An organization from which resources are ordered, mobilized or assigned to an incident and/or demobilized. The center may process requests, coordinate response, or track resources and information under the delegation of its benefiting agency(s).

Dispatch Center, Current The dispatch center actively supporting an incident and the resources assigned or a resource who is temporarily transferred for official action i.e. details, temporary duty station, etc. Definition extension: The current dispatch center for an incident may change to support other centers, units or agencies. The current dispatch center may be the same as the incident dispatch center or home dispatch center or may be different. Current dispatch center for tactical aviation resources is directly associated with the resource independent of an incident.



Dispatch Center, Home The dispatch center associated with a resource’s home unit. The Home Dispatch Center is responsible for initial mobilization and is the Center associated with the resource when an assignment is completed. Definition extension: Every resource has a home dispatch center.



Dispatch Center, Ordering The current dispatch center for an incident.

Dispatch Center, Sending Either the home or current dispatch center for a resource.

Dispersion The decrease in concentration of airborne pollutants as they spread throughout an increasing volume of atmosphere. see also: Dilution



Display Class In WIMS, a one-digit number representing the number of decision points used to evaluate the magnitude of the Staffing Index.

Display Class Breakpoints In WIMS, the climatological breakpoints separating the highest staffing levels. Commonly these are the index values corresponding to the 90th and 97th or 80th and 95th percentiles for the staffing index.

Distance Learning (DL) A concept of providing access to quality wildland fire education and training using appropriate instructional technology, delivered anywhere, anytime to prepare a fire management work force to safely achieve fire management objectives. see also: eLearning



Distance Measuring Equipment (DME) Aircraft navigational equipment that provides the slant range distance in miles (kilometers) from the aircraft to the VOR station to which the DME is tuned, usually at or near an airport.

Distributed Incident Simulation Exercise (DISE) An on-line mission rehearsal event providing an individual or team with an experiential learning environment utilizing the National Interagency Incident Management System to "game" a computer generated incident from multiple training locations. see also: Simulation



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 The ICS organization level between the branch and the task force/strike team. Divisions are used to divide an incident into geographical areas of operation. Divisions are established when the number of resources exceeds the span-of-control of the operations chief. see also: Group



Documentation Unit Functional unit within the planning section responsible for collecting, recording and safeguarding all documents relevant to the incident.

Dormant Season Burning Prescribed burning early in the dry season before the leaves and undergrowth are completely dry or before the leaves are shed, as an insurance against more severe fire damage later on.

Double Arsonist An offender who sets two fires at one site, at the same time, in a single event.

Double Doughnut Two lengths of hose rolled side by side or a single length rolled into two small coils for convenient handling. see also: Doughnut Roll



Double Female Coupling A hose-coupling device having two female swivel couplings to permit joining two male hose nipples of the same size and thread type when lines are laid with couplings in opposite or reverse directions.

Double Jacket Hose Fire hose having two cotton or other fiber jackets outside the rubber lining or tubing.

Double Male Coupling A hose-coupling device having two male thread nipples for connecting hose and for connecting two female couplings of the same diameter.

Double Shift Equipment is staffed with 2 operators or crews (1 per shift) and must be ordered and documented on a resource order. (Reference OF-294 general clauses for payment information.) Regardless of hiring method, on-shift time for operated equipment will be recorded with clock hours on the appropriate document, e.g., equipment hired under a daily rate will be posted with start and stop time for daily work.

Doughnut Roll A 50 or 100-foot length of hose or a 50-foot length of hose rolled up for easy handling. There are various ways of forming the doughnut. A convenient one has both couplings close together with the male thread protected by the female coupling. see also: Double Doughnut



Downloading A calculated reduction in actual 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 Line Fireline constructed by the front blade of a dozer. see also: Plow Line



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. see also: 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. see also: Backfire Torch; Burning Torch; Flame Thrower



Drive Axle An axle that supports a portion of the vehicle weight and transmits a driving force to the wheels.

Drive Wheels Wheels powered by all of the vehicle's drive axles. Dual tires are considered as single wheels. The number of wheels is commonly referenced by the terms "4x2", "4x4", etc. where the first figure indicates the total number of wheels on the ground and the second figure, the number of drive wheels.

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

Drop Configuration The type of retardant drop selected to cover a ground target. Terms that can specify the type of drop configuration include Salvo Drop and Trail Drop. see also: Salvo Drop; Trail Drop



Drop Pass Indicates that the airtanker has the target in sight and will make a retardant drop on this run over the target.

Drop Pattern The distribution of an aerially delivered retardant drop on the target area in terms of its length, width, and momentum (velocity x mass) as it approaches the ground. The latter determines the relative coverage level of the fire retardant on fuels within the pattern. synonym: 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 The government furnishes all operating supplies after the equipment arrives at the incident.

Dry Adiabatic Lapse Rate The rate of decrease of temperature with height of a parcel of dry air lifted adiabatically through an atmosphere in hydrostatic equilibrium. Numerically equal to 9.7670 C degrees per km or about 5.40 F degrees per thousand feet.

Dry Air Mass A portion of the atmosphere that has a relatively low dew point temperature and where the formation of clouds, fog, or precipitation is unlikely.

Dry Bulb A name given to an ordinary thermometer used to determine the temperature of the air (to distinguish it from the wet bulb).

Dry Bulb Temperature The temperature of the air measured in the shade 4-8 feet above the ground.

Dry Episode (DE) A contiguous series of days having a pre-established number of fire ignitions with a fuel dryness level that historically resulted in a significant fire event for a particular area. see also: Fuel Dryness Level; Significant Fire Event



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). Permanently installed supply private fire pumps which depend upon suction sources. Also called suction pipe.

Dry Lightning Storm Thunderstorm in which negligible precipitation reaches the ground. Also called dry storm.

Dry Run A trial pass over the target area by a leadplane and/or an airtanker to pinpoint target areas and warn ground personnel of the impending retardant or extinguishing agent drop.

Dry Storage Refers to dry chemical retardants stored at air attack bases and available for mixing with water. see also: Wet Storage



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.

Eddy A circular-like flow of a fluid (such as air or water) drawing its energy from a flow of much larger scale, and brought about by pressure irregularities as in the downwind (lee) side of a solid obstacle. For example, wind conditions may be erratic and may eddy on the downwind side of large rock outcroppings, buildings, etc.

Edge The place where plant communities meet or where successional stages or vegetative conditions within plant communities come together. The boundary between two fairly distinct fuel types.

Edge Firing Method of burning in which fires are set along the edges of an area and allowed to spread inward.

Eductor A device used to introduce and mix fire chemical into a water stream. An eductor is a fitting with three ports, an inlet for water flow, an outlet for water flow, and an inlet for fire chemical concentrate. The flow of water through the eductor produces a region of lower pressure at the fire chemical inlet, drawing the chemical into the water stream.

Effective Windspeed The midflame wind speed adjusted for the effect of slope on fire spread.

Ejector A siphon device used to fill an engine's tank when the water source is below or beyond the engine's drafting capability.

Elapsed Time The total time taken to complete any step(s) in fire suppression. NOTE: Generally divided chronologically into discovery time, report time, getaway time, travel time, attack time, control time, mop up time, and patrol time.

eLearning Conceptually represents the optimum integration of modern educational methods and professional staff development training with state of the art technology. The primary goal is enhancing on-the-job performance, motivation, and learning performance. see also: Distance Learning



Elevation Loss In hydraulics, the pressure loss caused by raising water through hose or pipe to a higher elevation (roughly equal to one psi for every two-foot increase in elevation above the pump) (11.3 kPa per meter).

Emergency Any incident which requires the response of a fire protection organization's attack units and/or support units.

Emerge