NWCG Glossary of Wildland Fire, PMS 205

The resource is committed and at the assigned incident.

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

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.

According to the American Meteorological Society, 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.

According to the American Meteorological Society, 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.

Limit the spread of fire by any appropriate means.

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. 

The starting date, hour, and minute of the first suppression work on a fire.

Single vehicle or aircraft and its associated personnel and material provided for the purpose of responding to and abating a fire or other emergency.

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.

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. 

An organization, office, or individual responsible for enforcing the requirements of a code or standard, or for approving equipment, materials, an installation, or a procedure.

Passengers may be transported in government aircraft only if they meet definition of an Official or an Unofficial Passenger.

A non-GOES telemetered weather station that provides hourly observations to a local database.

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

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

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

The resource can be used to fill a request. Resources on preposition incidents qualify as available.

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

Resources assigned to an incident and available for assignment.

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

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

According to the American Meteorological Society, 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.

A geospatial layer reference to activities that that may present a hazard to pilots during aviation operations displayed as a point.

A geospatial layer reference to activities that that may present a hazard to pilots during aviation operations displayed as a polygon.

Communication call sign assigned as a unique identifier to an aircraft.

A geospatial reference to physical features that may present a hazard to pilots during aviation operations displayed as a line.

A geospatial reference to physical features that may present a hazard to pilots during aviation operations displayed as a point.

A geospatial reference to physical features that may present a hazard to pilots during aviation operations displayed as a polygon.

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

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.

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

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

Angle or bearing 180 degrees opposite of azimuth.

A back bearing is measured from the object to your position. It is the exact opposite of a direct bearing.

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

Instantaneous explosion or rapid burning of superheated gases that occurs when oxygen is introduced into an oxygen-depleted confined space. It may occur because of inadequate or improper ventilation procedures.

A fire set along the inner edge of a fireline to consume the fuel in the path of a wildfire or change the direction of force of the fire's convection column.

A flame generating device (e.g., a fount containing diesel oil or kerosene and a wick, or a backpack pump serving a flame-jet).

A tactic associated with indirect attack, intentionally setting fire to fuels inside the control line to slow, knock down, or contain a rapidly spreading fire. Backfiring provides a wide defense perimeter and may be further employed to change the force of the convection column. Backfiring makes possible a strategy of locating control lines at places where the fire can be fought on the firefighter's terms. Except for rare circumstance meeting specified criteria, backfiring is executed on a command decision made through line channels of authority. 

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. 

A layer or rubber material used to provide adhesion between the inner tube and the outer jacket.

That portion of the fire with slower rates of fire spread and lower intensity normally moving into the wind and/or down slope.

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.

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).

A portable sprayer with hand-pump, fed from a liquid filled container fitted with straps, used mainly in fire and pest control.

A partitioned wall placed in vehicular or aircraft water tanks to reduce shifting of the water load when starting, stopping or turning.

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. 

A collapsible bucket slung below a helicopter. Used to dip water from a variety of sources for fire suppression.

The efficiency technology of either 25 KHz or 12.5 KHz in the frequency bands within the UHF/VHF ranges.