Wildland Firefighter Foundation
Wildland Firefighter Foundation

Fire Glossary

Click on the boxes below to view more information for each glossary definition, fire terminology, or abbreviation item:

  • A

    AA Air Attack: Light Command Aircraft (airplane or helicopter) that directs all the Air Resources over a fire (normally a Pilot and Batt. Chief)
    A Big Yellow McCloed: A Dozer digging line
    AB : Air Base
    Ac(ac) : A measurement of land; One acre comprises 4,840 sq. yds or 66 ft. X 660 ft.
    AC: Area Commander ; Aircraft
    ACDR: Area Commander
    ACT: Area Command Team
    Aerial Fuels: All live and dead vegetation in the forest canopy or above surface fuels, including tree branches, twigs and cones, snags, moss, and high brush.
    AEU: CALFIRE
    AIRIS: Aerial Infrared Imaging System
    Air Attack: 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
    ALDS: Automatic Lightning Detection System
    Alidade : A sighting device used by lookouts to determine the horizontal bearing and sometimes the vertical angle of a fire from a lookout
    ALS: II
    Anemometer : An instrument to measure wind speed
    Angle of Char Indicators : Standing fuels that are burned at an angle that indicates the direction of fire spread.
    ANF: Angeles National Forest
    Anchor and Hold: run tactics to protect nearby homes. SoCal CDF
    Anchor Point: A strategic and safe point, usually a barrier to fire spread, from which to start constructing fire line (or retardant line). An anchor point is used to reduce the chance of firefighters being flanked by fire.
    ARB: Air Resources Board
    Area Ignition : Delineated area surrounding a base which can be reached first by the ground or air attack units
    assigned to the base: assigned to the base
    Arson: At common law, the malicious and willful burning of anothers 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
    ASM: engine airplane that combines the lead plane
    Aspect: Cardinal direction toward which a slope faces
    ATGS: Air Tactical Group Supervisor
    ATMU: Atmospheric Theodolite Meteorological Unit (also known as an All Hazard Meteorological Response System AMRS)
    ATs: wing aircraft equipped to drop fire retardant
    AWS: Automated Weather Station
    Azimuth: 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.

  • B

    Back Fire: A fire set along the inner edge of a fire line to consume the fuel in the path of a wildfire and/or change the direction of force of the fire’s convection column
    Backing Fire: Fire spreading, or ignited to spread, into (against) the wind or down slope. 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
    Back Pump: filled container fitted with straps, used mainly in fire and pest control. (See also Bladder Bag.)
    BAER: Burned Area Emergency Rehabilitation
    Bambi Bucket: A collapsible bucket slung below a helicopter. Used to dip water from a variety of sources for fire suppression
    Banking Snag: The act of throwing mineral soil about the base of an unlighted snag to prevent its being ignited by a surface fire.
    Base: The part of the fire perimeter opposite the head
    Base Station: Desktop Radio or Scanner; A fixed central radio dispatching station controlling movements of one or more mobile units
    BBD: Bakersfield District
    BC: Battalion Chief
    BCMG: Base Camp Manager
    BDF: San Bernardino National Forest
    BDU: CALFIRE
    Bell Worm: A hot deep stump hole
    BEU: CALFIRE
    BI: Burn Index
    BIA: Bureau of Indian Affairs
    BIFC: Boise Interagency Fire Center
    Black: Area that has already been burned
    Black Line: burning of fuels adjacent to a control line before igniting a prescribed burn. Black lining 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 black line denotes a condition where there is no unburned material between the fire line and the fire edge
    Bladder Bag: strength nylon fabric fitted with a pump.
    BLM: Bureau of Land Management
    Blow Down: An area of previously standing timber which has been blown over by strong winds or storms
    Blow Out / Up: A sudden Acceleration of the Fire that has the potential to Jump the Fire line; A sudden increase in fire intensity or rate of spread strong enough to prevent direct control or to upset control plans
    BLS: Normally performed by EMTs
    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
    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
    Bowling for Hot Shots: Any time (either by natural causes or an inadvertent human cause) a large rock, log etc tumbles down hill scattering people working below. The decibel level of any verbal warning is in direct proportion to the mass of the falling object
    Box Canyon : A steep dead end canyon
    BR: Base Repeater
    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).
    Branch Director : Person under the direction of the operations section chief who is responsible for implementing that portion of the incident action plan appropriate to the branch
    Break Over: A fire edge that crosses a control line or natural barrier intended to confine the fire
    Brush Hook: A Hand Tool; 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
    BTU: CALFIRE
    Buffer Zone: An area of reduced vegetation that separates wildlands from vulnerable residential or business developments. This barrier is similar to a greenbelt in that it is usually used for another purpose such as agriculture, recreation areas, parks, or golf courses
    Buggie: A Crew Bus, Crew Haul or Transport
    Bump the Line: As in “when the fire bumps the line”, that is it tests the containment line. Embers or flaming brands may spot or roll over the line, spreading the fire and delaying containment
    Bump and Run: A highly mobile tactic used in interface structure protection. You don’t put any more than 150 feet of hose on the ground and you don’t hook up to a hydrant, so if the fire moves, you can move with it.
    Bump up Method: A progressive method of building a fire line 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 workers ahead move one space forward and resume work on the uncompleted part of the line. The last worker does not move ahead until completing his or her space.
    Burning Index: An estimate of the potential difficulty of fire containment as it relates to the flame length at the most rapidly spreading portion of a fire’s perimeter.
    Burn Out: Setting fire inside a control line to widen it or consume fuel between the edge of the fire and the control line
    Burn Over: A situation where personnel or equipment is caught in an advancing flame front

  • C

    Cache: determined complement of tools, equipment and/or supplies stored in a designated location, available for incident use
    CALCORD: police
    CALEMA: California
    CALFIRE: CDF
    CAMAC: Agency Command
    Candle or Candling: A single tree or a very small clump of trees which is burning from the bottom up
    Canopy: The uppermost spreading, branchy layer of vegetation
    Cardinal Points: North, South, East, West
    CCAD: CHPs Web Site
    CCD: Central California District
    CDCR: California Department of Corrections and Rehabilitation
    CDF: The old Name for California Department of Forestry
    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.
    Chains: A Chain Equals 66 Ft.(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).
    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 as a means of regulating the heat or intensity of the backfire
    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
    Chimney: When a fire is funneled up through a Canyon
    CIIMT: California Interagency Incident Management Team
    Clock Count or Method: The nose of any plane is 12 O’Clock, Tail 6 O’Clock, Right side of the plane looking from the tail forward 3 O’Clock, Left side 9 O’Clock, etc
    CNF: Cleveland National Forest
    Cold Trailing: Making sure the fire is dead out by testing for hotspots with your hands
    Column Collapse: These columns collapse once the heat generated at the surface by the fire is no longer sufficient to maintain an updraft. This can potentially happen at any time, and many columns (like showers and thunderstorms) go through many collapses and regeneration stages in any given day; As for telltale signs of collapse: If a column once looked impressive, and no longer does, pay close attention to the skies. Once those incredible updrafts that we see in these videos disappear, all that air + moisture + particulate matter begins to fall to the ground and creates erratic winds in the form of a downdraft.
    Com. : Command Frequencies for IC to run a fire on to clear the Normal Channel for regular use.
    COMC: Communications Coordinator
    Complex: Two or more individual incidents located in the same general area which are assigned to a single incident commander or unified command
    Configuration: How a helicopter is equipped, ie. Bambi Bucket or tanked
    Conflagration: A raging, destructive fire. Often used to connote such a fire with a moving front as distinguished from a fire storm
    Contained: When a fire has a natural barrier, dozer line, wet line, roads, scratch line, Retardant line, etc around it to keep it from spreading
    Control Line: An inclusive term for all constructed or natural fire barriers and treated fire edge used to control a fire’s spread
    Controlled: ups from within the perimeter of the fire will not break through this line.
    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 occures 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: the center of a low pressure area producing a net inflow of air. When this occures 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
    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
    Coverage Level: Density of retardant in drop. Normally ranges from 1 to 7 and represents the number of gallons in a 100 square foot area; 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.
    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.
    Coyote Tactics: sufficient crews that build fire line until the end of the operational period, remain at or near the point while off duty, and begin building fire line again the next operational period where they left off.
    Creeping Fire: Fire burning with a low flame and spreading slowly
    Crew: A group of firefighters operating as a unit, such as handcrew, engine crew, hotshot crew, helitack crew, etc.
    Cross Bearing: Intersecting lines of sight from two points to the same object, frequently used to determine location of a fire from lookouts
    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
    Crown Out: The ground area covered by the crown of a tree as delimited by the vertical projection of its outermost perimeter
    Crowning in the Leaf Litter: Oak/hickory type fire with 2 foot flame lengths
    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
    CRWB: Crew Boss
    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.
    Curing: Drying and browning of herbaceous vegetation or slash
    CWCG: California Wildland Fire Coordinating Group
    CWN: Private Equipment
    CYA: California Youth Authority
    CZU: CALFIRE.

  • D

    Daily Activity Level: caused fire source relative to that which is normally experienced. Five activity levels are defined: none, low, normal, high, and extreme
    Dead Fuels: bulb temperature, and solar radiation.
    Deep Seated Fire: A fire burning far below the surface in duff, mulch, peat, or other combustibles as contrasted with a surface fire.
    Defensible Space: An area either natural or manmade where material capable of causing a fire to spread has been treated, cleared, reduced, or changed to act as a barrier between an advancing wildland fire and the loss to life, property, or resources. In practice, “defensible space” is defined as an area a minimum of 100 feet around a structure that is cleared of flammable brush or vegetation
    Degradation: In a discussion of fire retardant slurries, deterioration of viscosity
    Deployment Zone: Deployment zones are last ditch areas where fire shelters must be deployed to ensure firefighter survival due to the available space and/or fire behavior conditions at the deployment zone location. Used when fire conditions are such that escape routes and safety zones have been compromised
    Dew Point: 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
    DFMO: District Fire Management Officer
    Die Out Pattern Indicator : Fingers or islands of less intensely burned areas or areas where the fire has self extinguished
    Direct Attack: Attacking the Fire Directly (placing Water, Retardant directly on the Flames)
    Directional Vectors: The physical characteristics of the indicators that show the direction of fire spread, i.e., advancing, backing, or lateral
    Dirt Darts: Smoke Jumpers
    Div. : control of the operations chief. A division is located with the Incident Command System organization between the branch and the task force/strike team.
    Divergence: The expansion or spreading out of a horizontal wind field. Generally associated with high pressure and light winds
    DIVS: Division Supervisor
    DMOB: Demobilization Leader
    DNR: Department of Natural Resources
    DOA: Department of Agriculture
    DOD: Department of Defense
    DOF: Department of Forestry
    DOI: Department of Interior
    Dope on a Rope: Helitack
    Down Drafts: downward moving air is the downdraft; The degree of atmospheric instability is one of the two major factors in determining the strengths of thunderstorm updrafts and downdrafts; vertical draft strengths basically determine the degree of storm severity.
    DOZB: Dozer Boss
    Dozer: Any tracked tractor with a Blade attached to the front
    Dozer Line: A fire line constructed by a Dozer
    DPIC: Deputy Incident Commander
    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.
    Drainage: Area drained by a river or stream. Usually includes at least one main canyon and several side canyons
    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
    Drift: Effect of wind on smoke, retardant drops, paracargo, smokejumper streamers, etc.
    Drip Torch: 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
    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
    Drop Point: The Point where and AT and/or Helo starts his Retardant Drop
    Drop Zone: The area around and immediately above the target to be dropped on
    Drought Index: A number representing net effect of evaporation, transpiration, and precipitation in producing cumulative moisture depletion indeep duff or upper soil layers
    Dry Bulb: bulb temperature is an indicator of heat content
    Dry Lightning: ground in which little or no precipitation reaches the ground. Type most likely to cause wildland fires
    Dry Mopping: Mixing dirt with embers from a hot spot or chopped off a log, spreading them out until feel no heat when cold trailing
    Dry Run: A trial pass over the target area by a lead plane and/or an airtanker to pinpointtarget areas and warn ground personnel of the impending retardant or extinguishing agent drop
    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

  • E

    EA: Extended Attack
    Edge Firing: Method of burning in which fires are set along the edges of an area and allowed to spread inward
    EMC: Moisture content that a fuel particle will attain if exposed for an infinite period in an environment of specified constant temperature and humidity. When a fuel particle reaches equilibrium moisture content, net exchange of moisture between it and the environment is zero.
    EMS: Emergency Medical Services
    EMTs: Emergency Medical Technicians; either I or IIs
    ENF: El Dorado National Forest
    Engine: 3
    Entrapment: threatening position where planned escape routes or safety zones are absent, inadequate, or compromised. An entrapment may or may not include deployment of a fire shelter for its intended purpose. These situations may or may not result in injury. They include “near misses.”
    Envelopment: Direct attack with multiple anchor points, that allows for multiple points of attack. Generally used as an engine tactic in the wildland urban interface
    ERC: The computed total heat released per unit area (British thermal units per square foot) within the fire front at the head of a moving fire.
    Escape Route: risk area, such as an already burned area, previously constructed safety area, a meadow that won’t burn, natural rocky area that is large enough to take refuge without being burned. When escape routes deviate from a defined physical path, they should be clearly marked (flagged).
    ETA: Estimated Time of Arrival
    EXCL: Exclusive use contract. Refers to aircraft that have an exclusive use contact with an agency
    Exposure: Property that may be endangered by a fire burning in another structure or by a wildfire. Direction in which a slope faces, usually with respect to cardinal directions. The general surroundings of a site with special reference to its openness to winds
    Extend: To drop retardant in such a way that the load slightly overlaps and lengthens a previous drop. “Extend your last drop
    Extreme Fire Behavior: “Extreme” implies a level of fire behavior characteristics that ordinarily precludes methods of direct control action. One of more of the following is usually involved: high rate of spread, prolific crowning and/or spotting: , presence of fire whirls, strong convection column. Predictability is difficult because such fires often exercise some degree of influence on their environment and behave erratically, sometimes dangerously.
    Eyes in Green: Handcrew watching the green side of the containment line that you don’t want to burn so as to be able to catch any spot fires

  • F

    FAE: Fire Apparatus Engineer
    Faller: A person on a Crew with a chainsaw who is responsible for falling trees
    FAMWEB: Fire and Aviation Management Web Applications system.
    FF: Fire Fighter
    FHL: Fort Hunter Ligget
    Final: Air Tanker or Helo will make his drop on this pass (Example : Tanker 76 On Final)
    Fingers: The long narrow tongues of a fire projecting from the main body
    Fire Break: A strip of land on which the vegetation is removed to mineral soil for fire control purposes.
    Fire Cache: A supply of fire tools and equipment assembled in planned quantities or standard units at a strategic point for exclusive use in fire suppression.
    Fire Front: The part of a fire within which continuous flaming combustion is taking place. Unless otherwise specified, the fire front is assumed to be the leading edge of the fire perimeter. In ground fires, the fire front may be mainly smoldering combustion.
    Fire Load: The number and size of fires historically experienced on a specified unit over a specified period (usually one day) at a specified index of fire danger
    Fire Pack: person unit of fire tools, equipment, and supplies prepared in advance for carrying on the back
    Fire Perimeter: The active burning edges of a fire
    Fire Plow: A heavy duty plowshare or disc plow usually pulled by a tractor to construct a fireline
    Fire Potential: The likelihood of a wildland fire event measured in terms of anticipated occurrence of fire(s) and management’s capability to respond. Fire potential is influenced by a sum of factors that includes fuel conditions (fuel dryness and/or other inputs), ignition triggers, significant weather triggers, and resource capability
    Fire Shelter: threatening situations, as a last resort.
    Fire Storm: like whirls.
    Fire Triangle or Tetrahedron: Instructional aid in which the sides of a triangle are used to represent the three factors (oxygen, heat, fuel) necessary for combustion and flame production; removal of any of the three factors causes flame production to cease
    Fire Weather Watch: A term used by fire weather forecasters to notify using agencies, usually 24 to 72 hours ahead of the event, that current and developing meteorological conditions may evolve into dangerous fire weather.
    Fire Whirl: Spinning vortex column of ascending hot air and gases rising from a fire and carrying aloft smoke, debris, and flame. Fire whirls range in size from less than one foot to more than 500 feet in diameter. Large fire whirls have the intensity of a small tornado
    Firing Out: The act of setting fire to unburned fuels located between the control line and main fire in burning out operations
    Fixed Tank: A device mounted inside or directly underneath an aircraft which can contain water or retardant for dropping onto a fire
    Fixed Wing: Air Tankers
    FKU: CALFIRE
    Flame Angle: Angle between the flame at the leading edge of the fire front and the ground surface, expressed in degrees
    Flank Fire: A firing technique consisting of treating an area with lines of fire set into the wind which burn outward at right angles to the wind
    Flank of the Fire: A side or sides of the fire; The parts of a fire’s perimeter that are roughly parallel to the main direction of spread. The left flank is the left side as viewed from the origin or base of the fire, looking toward the head
    Flare Up: A sudden acceleration of fire spread of intensity
    Flash Fuels: Highly combustible fine fuels such as grass, leaves, draped pine needles, fern, tree moss and some kinds of slash, which ignite readily and are consumed rapidly when dry
    FLIR : Hand held or aircraft mounted device designed to detect heat differentials and display their
    images on a video screen. FLIRs have thermal resolution similar to IR line scanners, but their spatial resolution is substantially less; commonly used to detect hot spots and flareups obscured by smoke, evaluate the effectiveness of firing operations, or detect areas needing mopup: images on a video screen. FLIRs have thermal resolution similar to IR line scanners, but their spatial resolution is substantially less; commonly used to detect hot spots and flareups obscured by smoke, evaluate the effectiveness of firing operations, or detect areas needing mopup
    Floto Pump: A portable floating pump (trade name)
    Foam and Go: moving interface fire, the practice of foaming a house and leaving it; to get out of the fire’s way or to move on to foam or defend another house. Often used when standing and defending the house puts the firefighters at great risk or when many houses can be protected by foaming. Requires engines equipped with CAFFS units
    Forb: like plant
    Forest: Is an area with a high density of trees
    Forward Rate of Spread: The speed with which a fire moves in a horizontal direction across the landscape, usually expressed in chains per hour or feet per minute
    FRA: Federal Responsibility Area
    FRF: Fremont National Forest
    Fuel Bed: An array of fuels usually constructed with specific loading, depth and particle size to meet experimental requirements; also, commonly used to describe the fuel composition in natural settings
    Fuel Break: A wide strip or block of land on which the vegetation has been permanently modified to a low volume fuel type so that fires burning into it can be more readily controlled
    Fuel Loading: The amount of fuel present expressed quantitatively in terms of weight of fuel per unit area
    Fuel Model: Simulated fuel complex (or combination of vegetation types) for which all fuel descriptors required for the solution of a mathematical rate of spread model have been specified
    Fuel Moisture Content: The quantity of moisture in fuel expressed as a percentage of the weight when thoroughly dried at 212 degrees Fahrenheit.
    Furlong: eighth of amile, 220yards, 660feet, 201.168meters, or 10chains
    FUMT: Fire Use Management Team (changed to Wildland Fire Management Team).

  • G

    GACC: Geographic Area Coordination Center
    Gobbler: Crown fire that’s goin’ and blowin’. A firestorm that destroys everything in its path
    Going Gunnysack: Describing a fire that just grew big enough to assume the characteristics of a nuclear bomb
    Greenor Green Belt: Area of the Fire that has not Burned
    Ground Pounders: Hand Crews
    Ground Fuel: All combustible materials below the surface litter, including duff, tree or shrub roots, punchy wood, peat, and sawdust, that normally support a glowing combustion without flame

  • H

    Haines Index: An atmospheric index used to indicate the potential for wildfire growth by measuring the stability and dryness of the air over a fire
    Hand Line: A fireline built with hand tools by a crew or firefighters
    Hang Up or Hanger : A situation in which a tree is lodged in another, preventing it from falling to the ground
    Hard Line or Booster Line: Reel Line (hose) on an Engine
    Heal of the Fire: Back edge of the fire
    Head of the Fire: The most rapidly spreading portion of a fire s perimeter, usually on the upslope side or depending on the Wind Direction
    Heavy Fuels: Heavy Brush to Timber
    Hectacre: Is a unit of area equal to 10,000 square meters (107,639 sq ft).
    Helibase: The main location within the general incident area for parking, fueling, maintaining, and loading helicopters. The helibase is usually located at or near the incident base
    Heliport: A permanent facility for the operation of helicopters which has been built to FAA standards and which is marked on aeronautical charts. Natural resource agencies refer to agency heliports as permanent helibases
    Helispot: A temporary landing spot for helicopters
    Helitack: The use of helicopters to transport crews, equipment, and fire retardants or suppressants to the fire line during the initial stages of a fire
    Helitack Crew: A group of firefighters trained in the technical and logistical use of helicopters for fire suppression
    Helitorch: An aerial ignition device hung from or mounted on a helicopter to disperse ignited lumps of gelled gasoline. Used for backfires, burnouts, or prescribed burns
    HFEO: Heavy Fire Equipment Operator
    Hide the Iron, Playing Hide the Iron: When there are FAR too many engines on a fire that’s pretty much dead. Spend most of the time looking for smokes that just aren’t there. The local district is charging the added iron to the fire so there are more resources available for a new start
    High Blading: A Dozer walking in (travelling) with its Blade Up
    Holding Action: Planned actions required to achieve wildland prescribed fire management objectives. These actions have specific implementation timeframes for fire use actions but can have less sensitive implementation demands for suppression actions
    Hoods in the Woods: Inmate Crews
    Hook: Term used to describe making a turn from the flank and across the head.
    Hose Lay: Arrangement of connected lengths of fire hose and accessories on the ground, beginning at the first pumping unit and ending at the point of water delivery
    Hot Line the Fire: Go to where the fire burns and cut line
    Hot Shots: A highly trained fire crew used mainly to build fireline by hand.
    Hot Shot Taxi: Helicopter
    Hot Shoveling: Working direct and tossing dirt from the fire’s edge onto the fire
    Hot Spot: A particularly active part of a fire
    Hot Spotting: Reducing or stopping the spread of fire at points of particularly rapid rate of spread or special threat, generally the first step in prompt control, with emphasis on first priorities
    HTF: Toiyobe National Forest
    Humping It: Walking or hiking hard, especially with a pack and/or equipment
    Humus : Layer of decomposed organic matter on the forest floor beneath the fermentation layer and directly above the soil. It is that part of the duff in which decomposition has rendered vegetation unrecognizable and mixing of soil and organic matter is underway
    HUU:Humboldt / Del Norte Unit – CALFIRE

  • I

    IA: Initial attack
    IAP: Contains objectives reflecting the overall incident strategy and specific tactical actions and supporting information for the next operational period. The plan may be oral or written. When written, the plan may have a number of attachments, including: incident objectives, organization assignment list, division assignment, incident radio communication plan, medical plan, traffic plan, safety plan, and incident map.
    IC: Incident Commander
    Ice Capping: Ice capping is just a term firefighters use to describe a fire when the plume from a fire has a distinct, bright white top to it. It takes a large size fire to generate an ice cap, so it is an indicator from a distance as to exactly how active a fire is and what it is currently doing
    ICP: Incident Command Post
    ICS: The combination of facilities, equipment, personnel, procedure and communications operating within a common organizational structure, with responsibility for the management of assigned resources to effectively accomplish stated objectives pertaining to an incident.
    IFR : Weather conditions below the minimum for flight under Visual Flight Rules and therefore requiring the observance of instruments inside the aircraft for controlling flight; generally considered to be less than 1000′ AGL and 3 miles distant
    IHC: Agency Hot Shot Crew
    Ignition Component: Indicates the probability of a firebrand producing a fire that will require suppression action. The higher the ignition component, the greater the chance that a catalytic converter, tossed cigarette or sparks from an unattended burning brush pile will start a fire. High temperature and low humidity are the major contributors to a high ignition component
    IMT : The incident commander and appropriate general and command staff personnel assigned to an incident (see also NIMO)
    Incendiary Device: Contrivance designed and used to start a fire
    Indirect Attack: Going indirect means that firefighters construct fireline at a distance from the active fire and may burnout to widen the line
    Incident Command Team: The incident commander and appropriate chief or command staff personnel assigned to manage an incident
    Incremental Drop: Air tanker drop in which tank doors are opened in sequence so that fire retardant cascades somewhat continuously.
    Independent Crown Fire: A fire that advances in the tree crowns alone, not requiring any energy from the surface fire to sustain combustion or movement
    INF: Inyo National Forest
    Infared Detection System: The use of heat sensing equipment, known as Infrared Scanners, for detection of heat sources that are not visually detectable by the normal surveillance methods of either ground or air patrols
    Initial Attack: The actions taken by the first units to arrive at a wildfire to protect lives and property, and prevent further extension of the fire
    Inversion Layer: an inversion is a layer of very stable air where the temperature increases with increase in altitude, inversions act as a lid and severely limit the amount of vertical motion in the atmosphere.
    Island: An unburned area within a fire perimeter

  • J

    Jettison: Disposing of water or retardant overboard to lighten an aircraft or helicopter
    Jumper: A firefighter who travels to fires by aircraft and parachutes into the fire area

  • K

    KBDI : used drought index adapted for fire management applications, with a numerical range from 0 (no moisture deficiency) to 800 (maximum drought).
    Kennel Up: Get on the Buggie
    KNF: Klamath National Forest
    Knock Down: To reduce flame or head in a specified target. Indicates the retardant load should fall directly on the burning perimeter or object
    KNP: Kings Canyon National Park
    KRN: Kern County Fire

  • L

    Ladder Fuels: used drought index adapted for fire management applications, with a numerical range from 0 (no moisture deficiency) to 800 (maximum drought).
    LAL: ground lightning. The scale is exponential, based on powers of 2 (i.e., LAL 3 indicates twice the lightning of LAL 2).
    LAC: Las Angeles County
    Land Mine: The results of someone taking a dump in the woods or along the fireline. Also known as a Cornback Rattlesnake
    Large Fire: For statistical purposes, a fire burning more than a specified area of land e.g., 300 acres in grass, 100 acres in timber or a Type 1 or Type 2 or NIMO team assigned.
    LAT: Large Air Tanker
    Lat. : west on maps, ranging from 0 at the equator to 90 at the poles (90 N or +90 for the North Pole and 90 S or 90 for the South Pole).
    Lawn Darts: Smoke Jumpers
    LCES: Look Outs, Communications, Escape Routes, Safety Zones
    Lead Plane: an Airplane used, under the Direction of the AA, to show the ATs where to place there Retardant Loads on a fire; Aircraft with pilot used to make trial runs over the target area to check wind, smoke conditions, topography and to lead air tankers to targets and supervise their drops
    LG: Local Government
    Light Engine : 6
    Light (Fine) Fuels: Normally grasses to light brush; These fuels readily ignite and are rapidly consumed by fire when dry.
    Limbing: Removing branches from a felled or standing tree, or from brush
    Line Cutter: Fire crew member in the progressive method of line construction who cuts and clears away brush, small saplings, vines, and other obstructions in the path of the fireline; usually equipped with ax or brush hook, or pulaski
    Litter: Top layer of the forest, scrubland, or grassland floor, directly above the fermentation layer, composed of loose debris of dead sticks, branches, twigs, and recently fallen leaves or needles, little altered in structure by decomposition
    Live Fuels: Living plants, such as trees, grasses, and shrubs, in which the seasonal moisture content cycle is controlled largely by internal physiological mechanisms, rather than by external weather influences
    LMU: CALFIRE
    LNP: Lassen National Park
    LNU: CALFIRE
    LO: Look Outs; Look Out Tower
    Load and Hold: An order given to the airtanker pilot to pick up another load of retardant or water and hold at the reload base. The tanker is still committed to the fire.
    Load and Return: Order given to the air tanker pilot to pick up another load of fire retardant or water and return to the fire
    Long Term Retardant: forming and intumescence
    Log. : Logisics
    Long. : Longitude; It is the angular (Vertical) distance measured east or west and usually expressed in degrees (or hours), minutes, and seconds, from the Prime Meridian.
    Low Pass: Low altitude run over the targeted area. May be used by air attack or lead plane to get a close look at the target or to show a tanker pilot a target which is difficult to describe. May be used by tanker pilot to get a better look at the target or to warn ground personnel of an impending drop
    LRA: Local Responsibility Area
    LZ: Landing Zone

  • M

    MAFFS: 130 (Hercules) cargo aircraft for use in dropping retardant on wildland fires.
    Main Ridge: Prominent ridgeline separating river or creek drainages. Usually has numerous smaller ridges (spur ridges) extending outward from both sides
    Mattock: Hand tool with a narrow hoeing surface at one end of the blade and a pick or cutting blade at the other end; used for digging and grubbing
    McLeod: A Hand Tool; 1/2 Brush Rake, 1/2 Scraping Blade (Wide Hoe)
    MCP: Marine Corp Pendleton
    Medium Fuels: Light Brush to Medium Brush
    Micro: REMS usually accompanies an incident meteorologist and ATMU to an incident
    Mineral Soil: Soil layers below the predominantly organic horizons; soil with little combustible material
    MNF: Mendocino National Forest
    MMU: CALFIRE
    MNU: CALFIRE
    MOB: Radio or scanner mounted in a vehicle
    Mobile Attack: To Attack a fire with an Engine while moving
    Monsoons : spring dry season which includes a “cold season” followed by a short “hot season” immediately preceding the rains, (b) a summer and early autumn rainy season which is usually very wet (but highly variable (but highly variable from year to year), and (c) a secondary maximum of temperature immediately after the rainy season
    Mop Shots: Hotshots who are complaining about being held for a mop up shift. Fedfire
    or Type 2 AD Crews mopping up: or Type 2 AD Crews mopping up
    Mop Up: To make a fire safe or reduce residual smoke after the fire has been controlled by extinguishing or removing burning material along or near the control line, felling snags, or moving logs so they won’t roll downhill.
    MR: Mountain Top Repeater
    MRA: Mutual Response Area
    MRN: Marin County Fire -(Contract County to CALFIRE)
    MVU:San Diego / Imperial Unit – CALFIRE

  • N

    Nativity Scene: A group of Chiefs, 3 or more, (usually Local Agency) that stand around and watch a wildfire running. They usually have their arms crossed and thoughtful expression on their faces
    NEU: Nevada / Yuba / Placer Unit – CALFIRE
    NFDRS: A uniform fire danger rating system that focuses on the environmental factors that control the moisture content of fuels..
    NIFC: Based in Boise, ID
    NIMO: National Incident Management Organization
    NOD: Northern Operations District
    NO OPs: North Operations

  • O

    OES: Office of Emergency Services (Now Named CALEMA)
    One Lick Method: A progressive system of building a fireline on a wildfire without changing relative positions in the line. Each worker does one to several “licks”, or strokes, with a given tool and then moves forward a specified distance to make room for the worker behind
    Open Line: Refers to open fire front where no line has been constructed
    Operational Period: The period of time scheduled for execution of a given set of tactical actions as specified in the Incident Action Plan. Operational periods can be of various lengths, although usually not more than 24 hours
    Orange Herd: CALFIRE Inmate Crew
    Orbit: A circular holding pattern of an aircraft around a fixed location often related to a wildland fire.
    ORC: Orange County
    Origin: The point where the fire started
    OS: On Scene
    Osborne Fire Finder : A sighting device used by lookouts to determine the horizontal bearing and sometimes the vertical angle of a fire from a lookout
    OSCC: making.
    Overwintering Fire: A fire that persists through the winter months until the beginning of fire season

  • P

    Pack Test: Used to determine the aerobic capacity of fire suppression and support personnel and assign physical fitness scores. The test consists of walking a specified distance, with or without a weighted pack, in a predetermined period of time, with altitude corrections
    Parallel Attack: Method of fire suppression in which fireline is constructed approximately parallel to, and just far enough from the fire edge to enable workers and equipment to work effectively, though the fireline may be shortened by cutting across unburned fingers. The intervening strip of unburned fuel is normally burned out as the control line proceeds but may be allowed to burn out unassisted where this occurs without undue delay or threat to the fireline
    Passive Crown Fire: A fire in the crowns of trees in which trees or groups of trees torch, ignited by the passing front of the fire. The torching trees reinforce the spread rate, but these fires are not basically different from surface fires
    Pat. : 6
    Pax: Passengers, of aircraft
    Pecker Pole: Small diameter tree, tall and skinny
    Pigs are Going to Die: Means that there’s a big fire, with a big base camp. With pork served every meal, it takes a lot of dead pigs to supply meat to the camp
    Pincer Attack: Direct attack around a fire in opposite directions by two or more attack units. Usually conducted from the fire’s tail to head
    Ping: 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).
    Piss Pump: Backpack pump
    Plow Line : Fireline constructed by a fire plow, usually drawn by a tractor or other motorized equipment
    PNF: Plumas National Forest
    Pole Patch: An area of downed and crisscrossed blowdown trees, generally but not always lodgepole
    Pongee Sticks: thick sticks cut off at an angle, about six inches off the groundyou get those on a sidehill and theyre just sucking chest wounds waiting to happen
    Prescribed Burn: Any fire ignited by management actions under certain, predetermined conditions to meet specific objectives related to hazardous fuels or habitat improvement. A written, approved prescribed fire plan must exist, and NEPA requirements must be met, prior to ignition
    Pre: Laying a retardant line in advance of the fire where ground cover or terrain is best for fire control action, or to reinforce a control line
    Psychrometer : bulb temperatures, which in turn are used to determine relative humidity and dew point
    Pulaski: A Hand Tool; Trenching tool 1/2 Axe, 1/2 Hoe

  • Q

    Quadrangle: Mapping unit which defines an area in terms of longitude and latitude distance. Two common scales are 1:24,000 quadrangles, which are 7.5′ longitude x 7.5′ latitude, and 1:62,500 quadrangles, which are 15′ longitude x 15′ latitude

  • R

    Radiant Heat Flux: The amount of heat flowing through a given area in a given time, usually expressed as calories/square centimeter/second
    Rapelling: producing devices
    RAWS: receiving station for use in the National Fire Danger Rating System among other predictive products
    Reburn: The burning of an area that has been previously burned but that contains flammable fuel that ignites when burning conditions are more favorable; an area that has reburned
    Recovery: The increase in fuel moisture as a result of increased relative humidity, usually occurring overnight. The general term used to describe the maximum overnight value of atmospheric relative humidity.
    Red Card: Fire qualification card issued to fire rated persons showing their training needs and their qualifications to fill specified fire suppression and support positions in a large fire suppression or incident organization
    Red Flag Warning: Term used by fire weather forecasters to alert forecast users to an ongoing or imminent critical fire weather pattern
    Rehabilitationor Rehab: The activities necessary to repair damage or disturbance caused by wildland fires or the fire suppression activity
    Rekindle: ignition due to latent heat, sparks, or embers or due to presence of smoke or steam
    Relay: Use of two or more fire pumps to move water a distance which would require excessive pressures in order to overcome friction loss if only one pump were employed at the source
    Reload Base: An airfield where air tankers are reloaded but not permanently stationed
    Repeater: A radio signal station that automatically relays a radio transmission, sometimes over a different frequency, thereby increasing the range of transmission. Repeaters are often named for the mountaintops or peaks where they are installed
    Resource Order: An order placed for firefighting or support resources
    Retardant: A substance or chemical agent which reduced the flammability of combustibles
    RH: Relative Humidity; The ratio of the amount of moisture in the air, to the maximum amount of moisture that air would contain if it were saturated. The ratio of the actual vapor pressure to the saturated vapor pressure.
    Rhino: welded on at a 90 deg. angle
    Ripper: A large fire
    RMP: A document prepared by field office staff with public participation and approved by field office managers that provides general guidance and direction for land management activities at a field office. The RMP identifies the need for fire in a particular area and for a specific benefit.
    Rock Roller: Dozer
    Romper: A large fire
    ROS: As fast as a normal person can run)
    ROSS: Resource Ordering and Status System, a new computer program used by dispatch
    Rotor: Helicopters
    Rotor Head: Helitack
    Rough: The accumulation of living and dead ground and understory vegetation, especially grasses, forest litter, and draped dead needles, sometimes with addition of underbrush such as palmetto, gallberry, and wax myrtle. Most often used for southern pine types.
    RP: Reporting Party
    RRU: CALFIRE
    Run: The rapid advance of the head of a fire with a marked change in fire line intensity and rate of spread from that noted before and after the advance.
    Running: defined head
    RX: Receives (radio)

  • S

    Saddle: Low gap or pass in a ridgeline
    Safety Zone: An area cleared of flammable materials used for escape in the event the line is outflanked or in case a spot fire causes fuels outside the control line to render the line unsafe. In firing operations, crews progress so as to maintain a safety zone close at hand allowing the fuels inside the control line to be consumed before going ahead. Safety zones may also be constructed as integral parts of fuel breaks; they are greatly enlarged areas which can be used with relative safety by firefighters and their equipment in the event of a blowup in the vicinity.
    Salvo: Dropping the entire load of retardant at one time, or dropping a combination of tanks simultaneously
    Santa Ana Winds: The Santa Ana winds are strong, extremely dry offshore winds that characteristically sweep through So. California in late fall into winter; Winds blow clockwise around high pressure in the Northern Hemisphere, which means that winds on the southern side of the high blow from the east toward the Pacific Ocean, toward lower offshore air pressure. The easterly winds push dry air from over the inland deserts of California and the Southwest. The winds blow over the mountains between coastal California and the deserts. As the wind comes down the mountains, it’s compressed and warms up. As the air warms, its relative humidity drops, sometimes to less than 20% or lower. The extremely low humidity helps dry out vegetation, making it a better fuel for fires. As the winds squeeze through canyons and valleys they speed up, fanning flames. In addition, as the winds whip over mountains and squeeze through canyons, friction helps create eddies, or swirling winds.
    SBC: Santa Barbara County
    Scratch Line: A preliminary control line hastily built with hand tools as an emergency measure to check the spread of a fire.
    Scorch Height: Average heights of foliage browning or bole blackening caused by a fire
    SCU: CALFIRE
    SEAT: Single Engine Air Tanker
    Secondary Line: overs and spot fires.
    Set: An individual incendiary fire. The point or points of origin of an incendiary fire. Material left to ignite an incendiary fire at a later time
    Shaded Fuel break: Fuel breaks built in timbered areas where the trees on the break are thinned and pruned to reduce the fire potential yet retain enough crown canopy to make a less favorable microclimate for surface fires
    Shake and Bake: Slang for Fire Shelter
    SHF: Shasta / Trinity National Forest
    Short Range Spotting: Firebrands, flaming sparks, or embers are carried by surface winds, starting new fires beyond the zone of direct ignition by the main fire. The range of such spotting is usually less than 1/4 mile.
    Short: Fire retardant that inhibits combustion primarily by the cooling and smothering action of water. Chemicals may be added to the water to alter its viscosity or retard its evaporation, thereby increasing its effectiveness
    Shoulder: Part of the Fire where the Flank turns towards the Head of the fire
    SHU: CALFIRE
    Side Hilling: Following a contour around a hill, usually on a steep slope
    Simms Bucket: leveling helibucket slung under a helicopter which can be filled by hovering over a water source
    Size Class of Fire : As to size of wildfire:
    Class A : fourth acre or less;
    Class B : fourth acre, but less than 10 acres;
    Class C : 10 acres or more, but less than 100 acres;
    Class D : 100 acres or more, but less than 300 acres;
    Class E : 300 acres or more, but less than 1,000 acres;
    Class F : 1,000 acres or more, but less than 5,000 acres;
    Class G : 5,000 acres or more.
    Size Up: To evaluate a fire to determine a course of action for fire suppression
    Skid Unit: contained unit consisting of a water tank, fire pump, and hose specially designed to be carried on a logging skidder for use in forest fire suppression
    SKU: CALFIRE
    Slash: Debris left after logging, pruning, thinning or brush cutting; includes logs, chips, bark, branches, stumps and broken understory trees or brush.
    Slimed: Hit by a load of Retardant
    Sling Load: Any cargo carried beneath a helicopter and attached by a lead line and swivel
    Slop Over: A fire edge that crosses a control line or natural barrier intended to contain the fire.
    SLU: CALFIRE
    Smoke Vent Height: Level, in the vicinity of the fire, at which the smoke ceases to rise and moves horizontally with the wind at that level.
    SMKJ: Smoke Jumper
    Smoldering Fire: Behavior of a fire burning without flame and with a slow spread
    Snag: A standing dead tree or part of a dead tree from which at least the smaller branches have fallen
    SNF: Sierra National Forest
    Snorkel Tank: driven snorkel attached. The helicopter hovers over the water source with the end of the snorkel immersed, the pump then fills the tank
    SOA: Scene of Action
    SO OPs: South Operations
    Sortie: Single round trip made by an air tanker from a tanker base to a fire and return
    Split Drop: compartment tank
    Spotter: In smokejumping, the person responsible for selecting drop targets and supervising all aspects of dropping smokejumpers
    Spot Fire: A fire ignited outside the perimeter of the main fire by flying sparks or embers
    Spotting: Behavior of a fire producing sparks or embers that are carried by the wind and start new fires beyond the zone of direct ignition by the main fire.
    Spot Weather Forecast: A special forecast issued to fit the time, topography, and weather of each specific fire. These forecasts are issued upon request of the user agency and are more detailed, timely, and specific than zone forecasts.
    Spread Component: Numerically equivalent to the rate of spread of a fire in feet per minute in the given fuel model. Spread component is most affected by fuel moisture and wind speed, and increases greatly on warm, dry, windy days.
    Spur Ridge: like, from a main ridge
    SQF: Sequoia National Forest
    SRA: State Responsibility Area
    SRF: Six Rivers National Forest
    ST: Handcrews
    Stack: foot (150 m) altitudinal separation between aircraft
    Staging Area (Staging): minute available basis. Staging areas are managed by the operations section.
    Starter, Repeater and Tactical: all refer to portable radio kits.
    STCR: Strike Team Leader Crew
    STDZ: Strike Team Leader Dozer
    STEN: Strike Team Leader Engine
    STF: Stanislaus National Forest
    Stump Humper: Horned tailed wasp, dangerous in NM, but ubiquitous across the mountain west, Appalachia; they are attracted to burning wood and smoke; they lay their eggs in freshly charred wood
    Sundowners: When the land is heated hotter than the ocean, the wind blows from cold to hot, onshore. When the land cools and becomes cooler than the water, the wind blows from cooler to warmer surface temperatures, offshore. Put a fire on the land and that can change the usual timing of the event. It is called a Sundowner because it happens after sundown.
    Surface Fire: Fire that burns surface litter, other loose debris of the forest floor, and small vegetation.
    Surface Fuel: Loose surface litter on the soil surface, normally consisting of fallen leaves or needles, twigs, bark, cones, and small branches that have not yet decayed enough to lose their identity; also grasses, forbs, low and medium shrubs, tree seedlings, heavier branch wood, downed logs, and stumps interspersed with or partially replacing the litter
    Swamper: (1) A worker who assists fallers and/or sawyers by clearing away brush, limbs and small trees. Carries fuel, oil and tools and watches for dangerous situations. (2) A worker on a dozer crew who pulls winch line, helps maintain equipment, etc., to speed suppression work on a fire.

  • T

    Tac. : Tactical, Tactics; Deploying and directing resources on an incident to accomplish the objectives designated by strategist
    Tag On: Connecting a (airtanker) drop to the forward part of a previous drop
    Tandem: Two or more units of any one type working one in front of the other to accomplish a specific fire suppression job; the term can be used in connection with crews of firefighters, power pumps, bulldozers, etc
    Task Force: 3 engines instead of 5
    T: Cards filled out with essential information for each resource they represent. The cards are color coded to represent different types of resources
    TCU: CALFIRE
    Team: The group of people who manage large fire or smaller fires, for example Type 1 Interagency Incident Management Team, Type 2 team, Type 3 Team. Composed of everyone from IC to people handling Ops and Finances, etc. This is in contrast to a Crew.
    Terrain Driven Wildfire: A fire driven by the topagraphy of the land, ie., fire runs faster up hill (depending on wind)
    Terra Torch: Device for throwing a stream of flaming liquid, used to facilitate rapid ignition during burn out operations on a wildland fire or during a prescribed fire operation
    TFLD: Task Force Leader
    TFR: Temporary Flight Restrictions
    TGU: CALFIRE
    Throw Out: Soil pushed over the edge of a fireline by a tractor plow or dozer; Also known as a berm
    TIA: Tule Indian Authority
    Tie In: To connect a retardant drop or a dozer line in with a specified point (road, stream, previous drop, etc.).
    Timed Out: When a Person, Operator, Pilot reaches the Max. hours they are allowed to work before they are required to take time off before they will be allowed to work again
    Tinder: Burnable organic material (duff, peat, rotten wood, etc.) with a high surface to volume ratio
    TMU: Lake Tahoe Management Unit
    TNF: Tahoe National Forest
    TOLC : offs and landings of helicopters at a helibase and any helicopter movement around the helibase and reports to the Helibase Manager
    Torching: up of a tree or small group of trees, usually from bottom to top.
    Tractor Plow : Any tractor with a plow for constructing fireline by exposing mineral soil.
    Trail : To drop tanks in sequence causing a long unbroken line
    Trench: A small ditch often constructed below a fire on sloping ground (undercut or underslung line) to catch rolling material
    TRPB: Tractor Plow Boss
    TTOP: Terra Torch Operator
    TUU: CALFIRE
    Turn the Corner: Contain a fire along a flank of the fire and begin containing it across the head. Refers to ground or air attack
    TWP: Township
    TX: Transmits (radio)
    Type: IA, 3, 4, etc.
    Type : 10, 747
    Type : Crew :Hot Shot Crews, Trained Crews
    Type : Dozer: Heavy Dozers
    Type : Engine: 1000 + gpm, 400 + gal., normally used for Structure Protection
    Type : Helo: 700 + Gal
    Type : 2999 gals retardant; P2V, SP2H
    Type : Crew :Untrained Crews
    Type : Dozer ;Medium Dozer
    Type : Engine: 500 + gpm , 400 + gal
    Type : Helo: 300 + gal
    Type : 802
    Type : Dozer ;Light Dozer
    Type : Engine: 120 + gpm, 300 + gal., normally used for Wildland fires (CALFIRE / USFS / BLM)
    Type : Helo :100 + gal
    Type : 599 gals retardant; AT602, Thrush
    Type : Engine: 50 + gpm, 200 + gal

  • U

    UAC: Unified Area Command
    UC: Unified Command
    UI: Urban Interface
    Underburn: A fire that consumes surface fuels but not trees or shrubs
    Up Drafts: The upward moving air in a thunderstorm is known as the updraft; The degree of atmospheric instability is one of the two major factors in determining the strengths of thunderstorm updrafts and downdrafts; vertical draft strengths basically determine the degree of storm severity.
    USDA: United States Department of Agriculture
    USFS: United States Forest Service
    UTF: Unable To Fill
    UTL: Unable To Locate

  • V

    Vectors: Directions of fire spread as related to rate of spread calculations (in degrees from upslope).
    V Pattern: To make two separate drops in an overlapping configuration, usually to stop the head
    VFR: Visual Flight Rules
    Virga: Rain or showers that evaporates before it reaches the ground
    VLAT: 10, 747, etc.
    VNC: Ventura County
    Vortex Turbulence: Miniature whirlwinds trailing from the wingtips of any aircraft in flight. Vortex will be in the form of a horizontal whirlwind with velocities up to 25 mph (40 km) per hour or more. Also created by action of rotor blades on helicopters; these whirlwinds tend to move downward toward the ground. If an aircraft flies low over a fire, vortices may reach the ground and suddenly cause violent and erratic fire behavior

  • W

    Water Dog: storm that has sent many a smokechaser on a wild goose chase, as it can easily be confused for a “real” smoke.
    Wet Bulb: is the temperature of adiabatic saturation. This is the temperature indicated by a moistened thermometer bulb exposed to the air flow; The wet bulb temperature is always lower than the dry bulb temperature but will be identical with 100% relative humidity (the air is at the saturation line).
    Wet Line: intensity fire.
    Wet Mopping: Mixing water with embers from a hot spot, spreading them out until feel no heat when cold trailing. Just watering from a piss pump is not enough, you have to stir things around
    Wet Water: Water with added chemicals, called wetting agents, that increase water’s spreading and penetrating properties due to a reduction in surface tension
    WFIP: A progressively developed assessment and operational management plan that documents the analysis and selection of strategies and describes the appropriate management response for a wildland fire being managed for resource benefits
    WFU: Wildland Fire Use; sometimes a Fire Use Management Team is called in if the best use is to let the fire burn to enhance the environment. See also WFRUB, the same thing
    WGBCC: Western Great Basin Coordination Center
    Whizzer: Unseen rock that flies by your head at night
    Widow Maker: Slang for a Snag; A loose limb or top or piece of bark lodged in a tree, which may fall on anyone working beneath it.
    Wildland / Urban Interface: The line, area or zone where structures and other human development meet or intermingle with undeveloped wildland or vegetative fuels.
    WIMS: An interactive computer system designed to accommodate the weather information needs of all federal and state natural resource management agencies. Provides timely access to weather forecasts, current and historical weather data, the National Fire Danger Rating System (NFDRS), and the National Interagency Fire Management Integrated Database (NIFMID).
    Wind: A wildland fire that is controlled by a strong consistent wind.
    Wind Shear: A variation in wind speed and/or direction in a layer of the atmosphere or between layers. The variation may be in the horizontal or vertical dimensions and may result in significant turbulence depending upon the magnitude of the wind speed/direction differences. A strong wind shear may act like an inversion and inhibit plume rise. It may also fracture the smoke plume, not allowing smoke to rise much above terrain levels. A strong horizontal anticyclonic shear results in downward motion and may bring smoke aloft to the surface
    Wind Vectors: Wind directions used to calculate fire behavior
    Wing Span: Term of measurement used to adjust the path of a tanker
    WOBS: Weather Observer
    Woodland: an area covered in trees, usually at low density, forming an open habitat, allowing sunlight to penetrate between the trees, and limiting shade
    WT: 4000 Gals.)

  • Y

    YNP: Yosemite National Park.