NWCG Glossary of Wildland Fire, PMS 205

The value specified by the manufacturer as the maximum allowable weight placed on an axle of a vehicle when fully equipped, including payload, fluids and occupants.

Actual vehicle weight, including chassis, body, cab, equipment, water, fuel, crew, and all other load.

The value specified by the manufacturer as the maximum allowable weight of a vehicle fully equipped, including payload, fluids and occupants.

Total allowable weight of a loaded aircraft for takeoff or landing, adjusted for altitude differences.

Reaction of a rotor downdraft against the ground surface, forming a "ground cushion" that increases lifting capability of that section of air.

Fire that consumes the organic material beneath the surface litter ground, such as a peat fire.

Emit flame and sparks which when set off adjacent to flammable vegetation can easily ignite a fire.
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Fog which extends vertically to less than 20 feet.

All combustible materials below the surface litter, including duff, tree or shrub roots, punky wood, peat, and sawdust, that normally support a glowing combustion without flame.

Speed with which an aircraft traverses the ground over which it flies.

Ground Support Unit staff provide ground transportation in support of incident operations. They maintain and repair vehicles and mobile ground support equipment and perform pre- and postuse inspections on all ground equipment assigned to the incident. The staff supply fuel for incident mobile equipment, and develop and implement the incident Traffic Plan. Additionally, during major incidents, Ground Support Unit staff maintain a transportation pool of vehicles (e.g., cars, buses, pickup trucks) suitable for transporting personnel, as opposed to tactical vehicles such as ambulances. Ground Support Unit staff also provide information to the Resources Unit on the location and status of vehicles assigned to the Ground Support Unit.

Verification at the site of what has been observed and/or measured from aircraft, satellites, other aerial platforms, aerial photographs, or maps.

Horizontal visibility observed at the ground.

An organizational subdivision established to divide the incident management structure into functional areas of operation. Groups are composed of resources assembled to perform a special function not necessarily within a single geographic area.

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.

A series of short, nearly parallel lines used in map making to represent a sloping surface. Representing a depression or pit, the contour line is joined forming a circle with the hachures on the inside of the circle.

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).

Vegetation baled, bundled or stacked that generate internal heat resulting in an ignition.

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.

An event, usually managed by organizations external to the fire community, for which the primary focus is for dealing with a hazardous situation that poses an unreasonable risk to health, safety, and property.

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 potential source of harm when accessing and using a water source.

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.

Pressure due to elevation of water. Equals 0.433 psi per foot of elevation. Back pressure.

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.