Fire Glossary
National Wildfire Coordinating Group Glossary of Wildland Fire Terminology
| Air Attack | Using airplanes or helicopters to help control a ground cover fire. Aircraft can also be used logistically to transport crews, supplies, and equipment. |
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| Air Tanker | Any fixed-wing aircraft used to drop retardant or water on a wildland fire. |
| Anchor Point | A term associated with attack methods. Refers to an advantageous location, usually one with a barrier to fire spread, from which to start constructing a fire line. Used to minimize the chance of being "flanked" by the fire while constructing the fire line. Most anchor points originate at or near the area of origin (rear of fire). |
| Aspect | A topography term for direction towards which a slope faces. |
| Backfiring | When attacking a wildland fire using the indirect attack method, intentionally setting fire to fuels inside the control line to reduce fuel and contain a rapidly spreading fire. Backfiring provides a wide defense perimeter and may be further employed to change the force of the fire's convective column. |
| Black Line | When putting in control lines, the process of burning out any pockets of unburned fuels. |
| Blowup | A dangerously rapid increase in fire spread. |
| Brush | Shrubs and stands of short, scrubby trees that do not reach merchantable size, generally 3' to 20' in height. |
| Brush Engine | Any light, mobile vehicle having limited pumping and water capacity, designed for initial attack knockdown of a small wildland fire. |
| Burning Out | When attack on the wildland fire is direct, or parallel with the control line, intentionally setting fire to unburned islands of fuel inside the control line to strengthen the line. |
| Camp | A geographic site within the general incident area, equipped and staffed to provide food, water, sleeping, and sanitary services to incident personnel. |
| Candling | Burning aerial canopy of one single tree from ground up. |
| Canopy | The foliage or leaf covering on fuel stock. |
| Cat Line | A fire line constructed by a bulldozer. |
| Cat Pile | A berm left by a bulldozer that might contain smoldering fuels. |
| Chain | A fire behavior term used to figure fire perimeter size and rate of spread. One chain equals 66 feet. |
| Class A Fire | Fires burning in natural fuels such as wood, paper, or other vegetative fuels. |
| Class B Fire | Fires burning in hydrocarbon fuels such as gasoline, oil, or diesel. |
| Clear Text | Use of plain language in radio communication transmissions, non-coded language. |
| Cold Trailing | To control a partly dead fire's edge by carefully inspecting and feeling with bare hands for any remaining embers or coals. |
| Command | The act of directing, managing, and/or controlling personnel and resources by virtue of explicit legal, agency, or delegated authority. |
| Company | Any piece of equipment having a full complement of personnel. |
| Conduction | The transfer of heat from one place to another without movement of the medium. |
| Conflagration | A raging, destructive fire. Often used to describe a fire burning under extreme fire weather. The term is also used when a wildland fire burns into a wildland/urban interface, destroying many structures. |
| Contain Fire | When firefighters or other resources stop the forward progress of a fire but have not put in all control lines. |
| Control Line | A term used for all constructed or natural fire barriers used to control a fire. |
| Control of Fire | When firefighters and/or other resources completely surround and leave no open line on the fire perimeter. |
| Convection | The transfer of heat by physical movement of a heated medium from one place to another. The convective column of a wildland fire can provide the medium. |
| Cooperative Agreements | Written documents made between unlike governmental bodies (for example state and federal) to provide assistance in terms of emergencies. |
| Crown Fire | Any fire that advances from top to top of trees or brush that is more or less independent of the surface fire. |
| Demob | An abbreviation for demobilization. The systematic release of personnel and resources from an incident. Demob should start during the incident's mobilization phase. |
| Direct Attack | Attacking the fire on its burning edge or close to it. A direct attack is usually made on a wildland fire that is moving slowly and is not too hot for firefighters to operate close to the fire's edge with equipment. |
| Division | The largest segment of a geographical fire perimeter. A division supervisor is in charge of operational activities with the division. Letters are assigned to describe a division. |
| Dozer | A heavy piece of equipment used to construct a fire line by clearing vegetation. |
| Drift Smoke | Smoke that has drifted from its point of origin and lost its original billowing form. Drift smoke can fill in canyons under stable air masses and make it difficult to see spot fires. |
| Drop | A term associated with air attack. Refers to dropped cargo, firefighters, or retardant. |
| Dry Lightning Storm | A lightning storm where little or no rain reaches the ground. |
| Duff | Matted, partly decomposed leaves, twigs, and bark beneath trees and brush. |
| Engine | Any fire vehicle providing specified pump, water, and hose capacities. |
| Engine Company | Any fire vehicle providing specified pump, water, hose, and a minimum of three firefighters. |
| Extended Attack | Fires that go beyond three burning periods. |
| Extreme Fire Behavior | When a wildland fire is influenced by adverse winds, fuels, adverse topography, or any combination of the above. High rates of spread, spotting, and thermal outputs are associated with extreme fire behavior. |
| Fine Fuel Moisture | A term expressing the moisture level (in percentage) found in fine fuels (such as grass). |
| Finger | Long, narrow extensions from the main body of the fire. |
| Fire Behavior | The manner in which a wildland fire develops; how fuels ignite, flame development, and fire spread. |
| Fire Break | An existing barrier, man-made or natural, that will stop or slow an oncoming wildland fire. |
| Fire Flank | The sides of a wildland fire between the tail and the head. Can be identified with compass directions, left and right, hot or cold. |
| Fire Line | The part of a control line that is scraped or dug down to mineral soil. |
| Fire Perimeter | The entire length of the outer edge of the fire. |
| Fire Retardant | Any substance or chemical applied to wildland fuels to slow the rate of combustion or reduce flammability, generally expressed as long-term or short-term. Long-term retardants are generally chemical based, whereas short-term retardants are primarily thickened soapy water. |
| Fire Season | The period of the year when wildland fires are most likely to occur. |
| Fire Storm | Violent convective columns caused by large continuous areas of fire, often appearing as tornado-like whirls. Can also occur from uneven terrain as fire spreads through an area. Are associated with extreme fire behavior. |
| Firing Team | Experienced wildland firefighters and firing boss in charge of carrying out backfiring or burn-out function. |
| Firing Out | Also called firing. The intentional setting on fire of fuels between the control line and the main body of fire in either a backfiring or burning-out operation. |
| Flanking | Attacking a wildland fire by working the sides of the fire between the head and rear. |
| Flash Fuels | Fuels like grass, leaves, pine needles, and tree moss that ignite readily and burn rapidly. Also called fine fuels. |
| Gradient Winds | Wind created by differing barometric pressures between high and low air-pressure systems. |
| Group | Resources assembled at an incident to perform a special function, not necessarily within a single geographic division. |
| Head of a Fire | The most active part of a wildland fire. A developing wildland fire can have multiple heads. |
| Heavy Fuels | Fuels of large diameter such as logs, snags, and large tree limbs. These ignite slowly and burn slow but hot. |
| Helibase | A location within the general incident area for parking, fueling, maintenance, and loading of helicopters. |
| Hose Lay | Connecting sections of fire hose together from the fire pump to the fire location with designated sections of line controlled by use of water. |
| Incendiary Fire | A wildland fire willfully set by anyone to burn wildland or property not owned or leased by this person. |
| Incident Action Plan (IAP) | The incident action plan contains objectives for the overall incident strategy and specific control actions for the next operational period of an incident. |
| Incident Commander | The officer in charge of the overall management of the incident. He or she is responsible for building management organization based on a span of control and incident complexity. There is only one incident commander per incident. |
| Incident Command System (ICS) | A broad term used to describe a management system for all risk incidents. It involves a combination of facilities, equipment, personnel, procedures,and communications operating within a common organizational structure. |
| Indirect Attack | A method of attack in which the control line is located along a natural barrier, firebreak, creek, river, or paved road. This attack method may be used in conjunction with backfiring. |
| Initial Attack (IA) | The first-alarm assignment (resources and personnel) dispatched to a wildland incident. |
| Inversion | A weather term used to describe when, in a given parcel of air, the air temperature increases with altitude. |
| Live Fuel Moisture (LFM) | A term describing moisture levels (expressed in percentage) found in brush and trees. |
| Local Wind | A wind whose velocity and direction is determined by local heating and cooling (diurnal cycle). Local winds are low velocity, averaging less than 10 mph. |
| Major Fire | Generally, a fire of the size or complexity that it requires a large force of fire resources and personnel and several days to control. |
| Mop-up | After the fire has been controlled, all actions required to make the fire "safe", prior to being called out. This includes trenching, falling snags, and checking all control lines. |
| Mutual Aid | An agreement made between like governmental bodies (such as federal and state) to provide assistance to each other in times of emergencies. |
| Operational Period | The period of time scheduled for execution of a given set of operation objectives as specified in the incident action plan. |
| Overhead | Personnel who are assigned to supervisory positions. This includes incident commander, command staff, directors, supervisors, and unit leaders. |
| Parallel Firing Method | A method where hand-tool crews operate 100 yards parallel to the fire's edge and burn out as they complete the fire line. |
| Progressive Hose Lay | A hose lay used on a wildland fire, usually on the flanks, to follow up a hand line made by crews or as a means of making a "wet line" along the fire's edge. Major components of this lay include 1 1/2-inch hose as a main feeder line with 1-inch hose branched off it, usually every 100 to 150 feet. |
| Project Fires | Fires that require a large amount of logistical and service support to suppress. Fires that need a supervisor in each of the five major functions of ICS. |
| Rate of Spread (ROS) | A fire behavior term used to express relative horizontal growth of a wildland fire. Expressed in total perimeter growth in chains per hour. One chain equals 66 feet. |
| Rear of Fire | The portion of a fire opposite the head. The slowest burning part of the fire. |
| Relative Humidity | A weather term. The amount of moisture in a given parcel of air expressed as a percentage of the maximum amount that parcel of air could hold at the same air temperature. |
| Strike Team | Specified combinations of the same kind and type of resources, with common radio communications and leader. |
| Surface Fire | A fire that burns surface litter like dry pine needles and leaves. |
| Swamper | A term associated with dozer operations. A swamper is the person or relief operator assisting dozer operator(s), often by driving a fuel or service tank. |
| Task Force | A set of resources with a common leader and communications temporarily assembled for a specific mission. Task forces are generally used for firing operations and structural protection. |
| Thermal Belts | In mountainous regions, the middle third of the slopes that remain active with fire during evening hours. This is due to down-canyon "falling" winds that pool cooler air in canyon bottoms but leave the middle part of the slope active. |
| Topography | An accurate and detailed description of a place, including land surface configuration, both man-mad and natural. Topography can be described in terms like "level", "steep", "broken", or "rolling". |
| Trenching | The action of digging trenches on a side slope to catch any material that might roll across the control lines. |
| Undercut Line | A control line constructed below a fire on a slope. |
| Unified Command | A method whereby agencies or individuals who have either geographic or functional jurisdiction at an incident can jointly determine overall objectives, select a strategy and establish common organizational objectives. This may be implemented in a variety of ways and does not compromise the principle of having only one incident commander. |
| Virga | A weather term describing moisture falling from clouds but not reaching the earth's surface. |
| Wet Line | Control line put in by means of a progressive hose lay using 1 1/2-inch feeder line with 1-inch branch lines every 100 to 150 feet. |
| Wind | The horizontal flow of air relative to the earth's topography and surface. |
| Wye | A hose fitting permitting two or more lines to be taken from a single supply line. Used frequently in progressive hose lays on wildland fires. |