NWCG Glossary of Wildland Fire, PMS 205

Prescribed burning or use of wildland fire during the photosynthetically-active growing season, where live fuel moistures are relatively high and the dominant vegetation, grasses, forbs, and herbaceous vegetation are fully greened.

Geographic subdivision of a fire-protected area, delimiting the initial attack bounds of a single fire guard or fire crew.

A dry chemical product which is mixed with water to form a fire retardant slurry.

Rapid fluctuations in wind speed with a variation of 10 knots (11.5 mph) or more between peaks and lulls.

An atmospheric index used to indicate the potential for wildfire growth by measuring the stability and dryness of the air over a fire.

A number of individuals that have been organized and trained and are supervised principally for operational assignments on an incident.

Fireline constructed with hand tools.

A situation in which a tree is lodged in another, preventing it from falling to the ground.

Noncollapsible suction hose attached to a pump and used to draft water from a source lower than the pump. Customary hose sizes in wildland fire engines are 2 and 2-1/2 inches in diameter (51 and 64 mm).

Any real or potential condition that can cause injury, illness or death of personnel, or damage to, or loss of equipment or property. The root cause of an unwanted outcome.

Assess hazards to determine risks. Assess the impact of each hazard in terms of potential loss, cost, or strategic degradation based on probability and severity.

A fuel complex defined by kind, arrangement, volume, condition, and location that presents a threat of ignition and resistance to control.

Map of the area of operations that shows all of the known aerial hazards, including but not limited to power lines, military training areas, hang gliding areas, etc.

A salary differential that compensates employees for exposure to hazards in the course of their duties.

Any treatment of living and dead fuels that reduces the potential spread or consequences of fire.

Those wildland areas where the combination of vegetation, topography, weather, and the threat of fire to life and property create difficult and dangerous problems.

Substances that are identified, classified, and regulated in the Code of Federal Regulations, Title 49 and Hazardous Materials Regulations 175.

A substance or material which has been determined by the Secretary of Transportation to be capable of posing an unreasonable risk to health, safety, and property when transported in commerce and which has been so designated.

A sufficient concentration of atmospheric aerosols to affect a visible attenuation of light and measurable reduction in visual range. The aerosol particle diameter is near the wavelength of visible light, optimizing the light scattering efficiency of the particles. 

Instrument for measuring the dependable range of distance at which a standard smoke column can be detected by the unaided eye under existing haze conditions.

A fire spreading or set to spread with the wind.

The most rapidly spreading portions of a fire’s perimeter, usually progressing with the wind, up slope, or a combination of the two.

Pressure due to elevation of water. Equals 0.433 pounds per square inch (PSI) per foot of elevation. (Approximately 0.5 PSI is required to lift water 1 foot in elevation)

The compass direction in which the longitudinal axis of the aircraft points.

Flashlight, ordinarily worn by firefighter on the front of the helmet.

Temperatures higher than that of the normal atmosphere, produced by the process of burning or oxidation.

The net amount of heat that would be given off if fuel burns when it is absolutely dry, noted as Btu per pound of fuel.

An area of low pressure caused by intense heating of the earth's surface. High surface temperature causes air to expand and rise, resulting in low atmospheric pressure and induces a weak inflow of air at the surface. Air which rises in a heat low is very dry so clouds seldom form. Rising air above a heat low produces a warm upper level high and results in a net outflow of air aloft. Heat lows remain practically stationary over areas which produce them. 

The heat energy resulting from the complete combustion of a fuel, expressed as the quantity of heat per unit weight of fuel. The high heat of combustion is the potential available, and the low heat of combustion is the high heat of combustion minus several losses that occur in an open system (primarily heat of vaporization of moisture in the fuel).

Total amount of heat released per unit area as the flaming front of the fire passes, expressed as Btu/square foot; a measure of the total amount of heat released in flames.

Apparatus used to detect heat.

Total amount of heat produced per unit mass of fuel consumed per unit time.

Amount of heat released to the atmosphere from the convective-lift fire phase of a fire per unit time.

Process by which heat is imparted from one body to another, through conduction, convection, and radiation.

A Heat Low which is elongated in shape.

The total heat energy released during combustion, usually published as units of heat energy produced per unit mass of ovendry fuel consumed.

The heat of combustion corrected for various heat losses, mainly the presence of moisture in the fuel. To a very close approximation, the quantity of heat per pound of fuel burned that passes through a cross section of the convection column above a fire that is burning in a neutrally stable atmosphere.

Any ground vehicle capable of transporting a dozer, tractor, or other heavy piece of equipment.

Fuels of large diameter such as snags, logs, large limbwood, which ignite and are consumed more slowly than flash fuels.

That portion of a fire backing directly away from and in relatively close proximity to the ignition area. The slowest spreading portion of a fire edge and generally opposite the head.

The vertical measurement of vegetation from the top of the crown to ground level.

Height above mean sea level in feet.

All control line that still contains the fire when mopup is completed. Excludes lost line, natural barriers not backfired, and unused secondary lines.

The main location within the general incident area for parking, fueling, maintenance, and loading of helicopters. It is usually located at or near the incident base.

A crew of individuals who may be assigned to support helicopter operations.

Specially designed bucket carried by a helicopter like a sling load and used for aerial delivery of water or fire retardants.

A ground service vehicle capable of supplying fuel and support equipment to helicopters.