Terms & Definitions
- Aerial canopy:
Fuel type comprised of trees having few low branches, making it
less susceptible to ignition by low-intensity fires.
- Air Attack:
Use of aircraft in support of ground resources to combat
wildfires, often most effective in initial attack in light
- Air drop:
Delivery of supplies or retardant from the air. Supplies can be
dropped by parachute. Retardant is dropped in a single "salvo" or
one or more "trails", the size of which is determined by the wind
and the volume, speed and altitude of the airtanker (usually no
less than 200 feet above the drop zone).
- Air operations:
Group tasked with coordinating aerial-based observation, supply,
rescue and suppression at a wildfire.
- Air Tactical
Group Supervisor or Air Attack: Coordinates air resources for
attack of a fire.
Fixed-wing aircraft certified by FAA as being capable of transport
and delivery of 600 to 3,0000 gallons of water or other liquid or
powder fire retardants. Formerly referred to as "borate bombers"
before borate-based retardants became less desirable. Often
accompanied by a spotter plane.
- Anchor point:
An advantageous location, usually a barrier to fire spread, from
which to start constructing a fireline. The anchor point is
used to minimize the chance of being flanked (or
outflanked) by the fire while the line is being constructed.
Precautionary fire set downwind of main fire for controlled fuel
clearing by "backing" it into the main fire, similar to burnout,
below, which occurs adjacent to control line.
- Backfire: A
fire set along the inner edge of a fireline to consume the fuel in
the path of a wildfire and/or change the direction or force of the
fire’s convection column.
- Bambi bucket:
collapsible bucket for lifting and moving water or other fire
retardant with a helicopter. (Note: The name was in use many years
before the trademark owner claimed it in 1983.)
Any obstruction to the spread of fire. Typically an area or strip
devoid of combustible fuel.
- Base: (1)
staging and/or command center location for fire operations; (2)
starting location of a fire; (3) base camp: location for eating,
sleeping, etc., near staging or command center.
- Berm: Soil
heaped on the downhill side of a traversing fireline below a fire,
to trap rolling firebrands.
A condition where no combustible fuels remain between the fireline
and the main fire.
Sudden increase in fireline intensity or rate of spread of a fire
sufficient to preclude direct control or to upset existing
suppression plans. Often accompanied by violent convection and may
have other characteristics of a firestorm.
Interagency Fire Center (BIFC): The former name of the
National Interagency Fire Center (see below); often pronounced as
- Booster hose,
booster pump, booster reel: small solid hose on a reel
connected to a small pump fitted to a water tank on a vehicle.
Booster pump also refers to pump in a relay series for pumping
uphill beyond the lift of the previous pump.
- Brush blade:
Rake attachment for cutting or ripping brush and roots out of a
- Brush hook:
Cutting tool used to clear brush, longer than a machete, usually
with a heavy, solid, curved blade bolted to the end of an
- Brush truck:
Small fire truck outfitted for wildland fire. Also called a "Type
- Bump up: To
move to another location. Can refer to anything from moving to
another location on a fireline, to an entire crew moving to
another fire. "Bump back" means to return to your previous
location. In the "bump" system of fireline construction, each
firefighter works on a small piece of fireline with his or her
tool, perhaps slowly walking as the line progresses, until a
completed portion of line is encountered. Then the call to "bump
up!" is heard, and everyone ahead of the caller skips ahead one or
more positions, leaving the unfinished fireline for those coming
- Burning index:
relative measure of fire-control difficulty; doubling the index
means twice the effort may be needed to control the fire (e.g.,
wind shift, heavier fuel load, etc).
- Burn out:
Setting fire inside a control line to consume fuel between the
edge of the fire and the control line.
- Burning period:
The part of each 24-hour period when fires spread most rapidly;
typically from 10:00 AM to sundown.
- Closed area:
An area in which specified activities or entry are temporarily
restricted to reduce risk of human-caused fires.
Legal restriction, but not necessarily elimination, of specified
activities such as smoking, camping, or entry that might cause
fires in a given area.
- Cold trailing:
A method of controlling a partly dead fire edge by carefully
inspecting and feeling with the hand for heat to detect any fire,
digging out every live spot, and trenching any live edge.
Two or more individual incidents located in the same general area
which are assigned to a single incident commander or unified
- Confine a fire:
The least aggressive wildfire suppression strategy which can be
expected to keep the fire within established boundaries of
constructed firelines under prevailing conditions.
- Contain a fire:
A moderately aggressive wildfire suppression strategy which can be
expected to keep the fire within established boundaries of
constructed firelines under prevailing conditions.
- Control line:
An inclusive term for all constructed or natural barriers and
treated (retardant) fire edges used to control a fire.
- Controlled burn:
A Prescribed Burn.
- Coyote tactics:
A progressive line construction duty involving self-sufficient
crews which build fireline until the end of the operational
period, remain at or near the point while off duty (in a spike
camp), and begin building fireline again the next operational
period where they left off.
- Creeping fire:
Fire burning with a low flame and spreading slowly.
- Crown fire:
A fire that advances from top to top of trees or shrubs more or
less independent of a surface fire. Crown fires are sometimes
classed as running or dependent to distinguish the degree of
independence from the surface fire.
- Crown out:
A fire that raises from ground into the tree crowns and advances
from treetop to treetop. To intermittently ignite tree crowns as a
surface fire advances.
- Dead Man Zone:
Unburned areas around edges of brush fire.
Demobilization, or a crew being removed from working a fire.
- Direct Attack:
Any treatment applied directly to burning fuel such as wetting,
smothering, or chemically quenching the fire or by physically
separating the burning from unburned fuel.
- Dozer line:
Fireline constructed by the front blade of a bulldozer or any
tracked vehicle with a front mounted blade used for exposing
mineral soil. Also "catline."
using a suction pump to lift water from below the pump, using a
semi-rigid suction hose, typically to fill a portable reservoir
that has other suction pumps (to relay) or siphon hoses running
downhill to their nozzles.
- Drip torch:
hand-carried fire-starting device filled with flammable liquid
that is poured across a flaming wick, dropping flaming liquid onto
the fuels to be burned.
- Duff: Layer
of decaying forest litter consisting of organics such as needles,
leaves, plant and tree materials covering the mineral soil. Duff
can smolder for days after a fire. Extinguishing smoldering duff
is key to successful mopup operations.
- Engine: Any
ground vehicle providing specified levels of pumping, water, and
hose capacity but with less than the specified level of personnel.
- Engine crew:
A number of personnel trained and supervised to respond to
incidents using an engine. Typically much smaller than a hand
- Escape fire:
An intentional fire ignited by a fire crew, usually in a grassland
environment, to escape a dangerous situation.
- Escaped fire:
A fire, which has exceeded or is expected to exceed initial attack
capabilities or prescription.
- Extended attack:
Situation in which a fire cannot be controlled by initial attack
resources within a reasonable period of time. Committing
additional resources within 24 hours after commencing suppression
action will usually control the fire.
- Fire behavior:
The manner in which a fire reacts to the influences of fuel,
weather, and topography.
- Fire camp:
Temporary camp established at large fires to provide food, rest,
and other necessities to fire crews.
A natural or constructed barrier used to stop or check fires that
may occur, or to provide a control line from which to work.
- Fire edge:
The boundary of a fire at a given moment.
The part of a control line that is scraped or dug to mineral soil.
Also called fire trail. More generally, working a fire is called
being "on the fireline." May also refer to a "wet line" where
water has been used to create a burn boundary in light fuels such
handbook: A small red booklet carried by U.S. firefighters on
the firelines, as a quick reference on various firefighting
- Fire retardant:
Any substance (except plain water) that by chemical or physical
actions reduces flammability of fuels or slows their rate of
combustion. See retardant slurry, AFFF, and Foam
- Fire Lookout:
A person that keeps an eye for possible fire starts and
conditions. They can work in a Fire Lookout Tower or perform the
duty as a role for a fire crew on the fireline.
- Fire lookout
tower: A structure located at a high vantage point to house
and protect the person performing the duties of a Fire Lookout.
- Fire shelter:
An aluminized tent offering protection by means of reflecting
radiant heat and providing a volume of breathable air in a fire
entrapment situation. Carried as a safety tool, fire shelters
should only be used in life threatening situations, as a last
resort, as severe burns or asphyxiation often result.
- Fire shirt:
Distinctive yellow shirts made of Nomex or other lightweight
materials of low combustibility, used as uniform
PPE of wildland firefighters.
Extreme fire behavior indicated by widespread in-drafts and a tall
column of smoke and flame, where added air increases fire
intensity, creating runaway fire growth.
- Fire weather:
weather conditions that affect fire vulnerability, fire behavior
- Flanks of a
fire: The parts of a fire’s spread perimeter that are roughly
parallel to the main direction of spread.
Any sudden acceleration in rate of spread or intensification of
the fire. Unlike blowup, a flare-up is of relatively short
duration and does not radically change existing control plans.
- Flash fuels:
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.
- Foam: The
aerated solution created by forcing air into, or entraining air in
water containing a foam concentrate by means of suitably designed
equipment or by cascading it through the air at a high velocity.
Foam reduces combustion by cooling, moistening and excluding
Federal Supply Service
A natural or manmade change in fuel characteristics which affects
fire behavior so that fires burning into them can be more readily
- Fuel load:
the mass of combustible materials available for a fire usually
expressed as weight of fuel per unit area (e.g., 20 tons per
- Fuel moisture:
Percent water content of vegetation, an important factor in rate
of spread, ranging from dead-fuel and fine-fuel moisture (FFM), of
10 percent or less, to live-fuel moisture (LFM), of 60 percent or
more. FFM can be estimated by weighing calibrated wood sticks.
- Fuel type:
An identifiable association of fuel elements of distinctive
species, form, size, arrangement, or other characteristics that
will cause a predictable rate of spread or resistance to control
under specified weather conditions.
- Ground fire:
Fire that consumes the organic material beneath the surface litter
ground, such as peat fire.
- Hand crew:
A number of individuals that have been organized and trained and
are supervised principally for operational assignments on an
incident. In the United States, a typical hand crew is 20 in
- Head of a fire:
The most rapidly spreading portion of a fire’s perimeter, usually
to the leeward or up slope.
- Heavy fuels:
Fuels of large diameter such as snags, logs, large limb wood,
which ignite and are consumed more slowly than flash fuels.
- Helispot: A
natural or improved takeoff and landing area intended for
temporary or occasional helicopter use, typically in remote areas
without other access.
- Helitack: A
fire crew trained to use helicopters for initial attack, and to
support large fires through bucket drops and the movement of
personnel, equipment and supplies.
- Hot spot: A
particularly active part of a fire.
- Hotshot crew:
Intensively trained fire crew used primarily in hand line
construction, and organized primarily to travel long distances
from fire to fire as needed rather than serving only one
Command System (ICS): System first developed to provide a
command structure to manage large wildfires in the United States,
now widely used by many emergency management agencies.
- Indian pump:
Water vessel carried on one's back, either a rigid can or
collapsible bag, with a hose and telescoping squirt pump. Contains
5 US gal, and is used on hot spots and during mop up. Also called
bladder bag (if collapsible), piss pump, or Fedco.
- Indirect attack:
A method of suppression in which the control line is located some
considerable distance away from the fire’s active edge. Generally
done in the case of a fast-spreading or high-intensity fire and to
utilize natural or constructed firebreaks fuel breaks and
favorable breaks in the topography. The intervening fuel is
usually backfired; but occasionally the main fire is allowed to
burn to the line, depending on conditions.
- Infrared (IR)
detector: A heat detection system used for fire detection,
mapping, and hotspot identification.
- Initial attack:
The actions taken by the first resources to arrive at a wildfire
to protect lives and property, and prevent further extension of
- Interface zone:
Where urban firefighting meets wildland firefighting. Structures
at the edges of wildlands are threatened and require skills and
equipment of both disciplines.
- Knock down:
To reduce the flame or heat on the more vigorously burning parts
of a fire edge.
Ladder fuels: Flammable vegetation that helps a ground
fire move into the canopy.
Firefighter safety mnemonic for Lookouts, Communications, Escape
routes, Safe zones.
- Lead plane:
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.
policy: Administrative decision to defer fire suppression,
perhaps because of wilderness and long-term forest conservation
- Light 'em,
fight 'em: Derogatory term for wildland crew with a reputation
for igniting its prescribed burns carelessly.
- Line firing:
Surface buildup of leaves and twigs.
- Logging slash
or logging debris:
Helicopter arrangement for lowering external loads into areas not
available for landing.
(1) Safety person positioned to monitor the location and behavior
of a fire, ready to sigal a crew to escape; (2)
Fire lookout tower or fire tower, often on mountain-tops,
for viewing the surrounding countryside and watching for signs of
Fire lookout, the person who works in the fire lookout
tower; (4) The "L" of "LCES" safety mnemonic, which see
Hand tool used in fireline construction, consisting of a
combination rake and hoe.
Extinguishing or removing burning material near control lines,
felling snags, and trenching logs to prevent rolling after an area
has burned, to make a fire safe, or to reduce residual smoke.
- Mutual aid:
cross-jurisdictional assistance with emergency services by
National Fire Protection Association (NFPA): Fire and
safety standards organization; issues various wildfire-oriented
standards related to clothing, tactics, equipment, etc.
- National Hose
(NH): National Standard Thread (NST) design of threaded
couplings used on fire hose in various diameters.
National Interagency Fire Center (NIFC): Coordination
Boise, Idaho, operated by several U.S. agencies to provide
logistics, weather information and resource coordination for
wildfire suppression across the U.S. (formerly BIFC).
Brand of approved, fire retardant, synthetic, aramid cloth and
thread used in personal protective equipment for wildland
firefighting, and jumpsuits.
National Wildfire Coordinating Group: Coordination agency
located in Washington, D.C. which sets national standards for
firefighter training and publishes training manuals.
- One-hour fuel:
Vegetation with large surface-to-mass ratio, a so-called "fine
fuel" (along with 10-hour) that quickly reaches critical (inflammable)
moisture levels (fine fuel moisture, FFM) when exposed to heat;
compare with 100-hour or 1000-hour fuels (i.e., live fuel
moisture, LFM), which take much more heat to ignite.
Personnel assigned to supervisory positions, including Incident
Commander, Command Staff, General Staff, Branch Directors,
Supervisors, Unit Leaders, Managers, and staff.
- Palmer drought
severity index (PDI): Technique for measuring impact of soil
moisture changes on vegetation, for predicting fire danger and
attack: Fire containment method where crews constructs
fireline at some distance from the edge of the fire (e.g., 100
yards) and then burn out the fuel in the buffer as the
fireline is completed.
grasses: an extremely volatile fuel, after curing, in May,
June, July, which can lead to large, fast fires that may reach
- Point of
origin: an element of fire behavior, indicating where a
fire began, supporting further analysis of where the fire went or
will go; evidence of specific origin is often obscured or
destroyed by suppression tactics.
- Prescribed burn:
Deliberately ignited fire for the purpose of forest or prairie
management, often to remove heavy fuel buildup or simulate natural
cycles of fire in an ecosystem. Also called "controlled burn",
even if it becomes uncontrollable.
hose lay: A method of deploying hoses along firelines during
suppression and as they are built and reinforced, typically using
1 1/2-inch supply lines, gated wyes and 1-inch lateral lines with
nozzles (or at least spigot valves) every 100 feet or so. As the
line progesses, more hoses and valves are added.
- Project fire:
Any large fire requiring extensive management and the
establishment of a temporary infrastructure to support
firefighting efforts, such as fire camps.
Combination axe and grub hoe tool with a straight handle, used for
building handline. Also known as "P-tool"
Crew of specialist hot-shot firefighters who are trained to access
a fire area by sliding down ropes suspended from a hovering
helicopter. Also used for delivering wilderness first aid if a
Rapeller is an EMT.
- Reburn: (1)
Repeat burning of an area over which a fire has previously passed,
but left fuel that later ignites when burning conditions are more
favorable; (2) An area that has re-burned.
- Red card:
Credentials issued to qualified wildland firefighters, listing
their qualifications and specialties.
- Red-flag day:
A Red Flag Warning means that critical fire weather conditions are
either currently occurring or will shortly. A combination of
strong winds, low relative humidity and warm temperatures could
create explosive fire growth potential. Weather conditions
creating a critical fire hazard, may require closing the forest to
non-emergency activities in order to minimize the risk of
accidental wildland fires.
The basic wildland fire training course given to all U.S.
firefighters before they can work on the fire lines.
- Safety zone:
An area cleared of flammable material 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 blowup in the vicinity.
Chainsaw crew, may also include ‘’’faller’’’ or ‘’’feller’’’ who
is qualified to cut down trees or snags, perhaps while the tree or
snag is burning.
- Secondary line:
Any fireline constructed at a distance from the fire perimeter
concurrently with or after a line already constructed on or near
to the perimeter of the fire. Generally constructed as an
insurance measure in case the fire escapes control by the primary
- Skidder unit:
Pre-configured tank, pump, hose for attachment to a logging
skidder (large 4-wheel-drive tractor with a dozer blade, winch or
grapple) to be carried to a fireline.
Debris resulting from such natural events as wind, fire, or snow
breakage; or such human activities as road construction, logging,
pruning, thinning, or brush cutting. It includes logs, chunks,
bark, branches, stumps, and broken under-story trees or brush.
Fire spreading outside the boundaries of a control line.
Humorous pejorative term for those believed to be doing less work
than you. "Heli-slug" for helitack, "camp slug" for fire camp
support personnel, "engine slug" for engine crew member, etc.
- Slurry bomber:
Colloquial term for a wildland firefighter. Now mostly archaic,
except in Minnesota where state Department of Natural Resources
firefighters are officially known by that name.
A specifically trained and certified firefighter who travels to
remote wildfires by fixed-wing aircraft and parachutes into a jump
spot - that may include trees - close to the fire.
A fire burning without flame and barely spreading.
- Spike camp:
Remote camp usually near a fireline, and lacking the logistical
support that a larger fire camp would have.
Behavior of a fire producing sparks or embers that are carried by
the wind and which start new fires (spot fires) beyond the zone of
direct ignition by the main fire. A cascade of spot fires can
cause a blowup.
- Strike team:
Specified combinations of the same kind and type of resources,
with communications, and a leader.
All the work of extinguishing or confining a fire beginning with
crew: Two or more firefighters stationed at a strategic
location for initial action on fires. Duties are essentially the
same as those of individual firefighters.
- Surface fire:
Fire that burns loose debris on the surface, which include dead
branches, leaves, and low vegetation.
- Task force:
Any combination or single resources assembled for a particular
tactical need, with common communications and a leader. A Task
Force may be pre-established and sent to an incident, or formed at
- Tree jump:
A Smokejumper can sometimes parachute into the tree canopy if a
clearing is not available or suitable.
- Turn Around:
A widened part of a fire break used for turning vehicles around,
also used as a safe area during entrapment.
- Understory burn:
A controlled burn of fuels below the forest canopy, intended to
remove fuels from on-coming or potential fires.
- Urban interface:
The Interface zone where man-made structures inter-mingle with
wildlands, creating risk of structural involvement in a wildland
- Watch out
situations: A list of 18 situations for firefighters to be
aware of, which signal potential hazards on the fire line.
- Water tender:
Any ground vehicle capable of transporting specified quantities of
- Web Gear:
Any harness or belt which supports a field pack, fire shelter,
canteens, radio or other necessary equipment carried by a
- Wet line:
Temporary control line using water or other fire retardant liquid
to prevent a low-intensity fire from spreading in surface fuels.
- Wildfire: A
fire occurring on wildland that is not meeting management
objectives and thus requires a suppression response.
An area in which development is essentially nonexistent, except
for roads, railroads, power lines, and similar transportation
facilities. Structures, if any, are widely scattered.
Tree knocked over or broken off by wind, increases fuel loading
and hampers building fireline. Also sometimes called blowdown.