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Glossary of Terms

used in

Forest Fire Control

Agriculture Hanähcx^ "Hß. 104

Forest Service

UNITED STATES DEPARTMENT OF AGRICULTURE
FOREWORD

Standard definitions are needed for special terms peculiar to any profession,

art, or science. Uniform terminology is essential for comprehensive interchange

of ideas between workers either by word of mouth or by writing.

New terms and concepts have been introduced in fire control in the United

States since 1939, when the second edition of "Glossary of Terms Used in Fire

Control" was published. More concise meanings have furthermore developed

for some old and accepted terms, whereas other terms have become obsolete.

About 100 new definitions have been added and about 200 former definitions

have been revised in wording or meaning.

This third edition of the glossary is intended primarily for those engaged in

fire control and for the forest school student. Only those special terms and

definitions likely to be needed by forest school students and fire control workers

have been included. Teims related to special fields of fire control and related

sciences that concern relatively few students or workers have been excluded if

definitions are available in glossaries or handbooks pertaining to those fields.

Fire-weather forecast terms, omitted here, are given in "Fire Weather Forecast

Terminology'' published by the U. S. Weather Bureau. Some additional aerial

transportation, cargo, and reconnaissance terms are given in "Air Operations

Handbook'' published by the U. S. Forest Service.

Terms used in only one region have usually been omitted. Since by défini'

tion, a glossary explains terms that have a technical meaning not clearly implied

by the usual sense of the words, words used in the dictionary sense and terms

that are self-explanatory have been largely excluded. Terms upon which many

workers in the field of forest-fire control disagree have usually been excluded.

Details and examples unnecessary for a precise definition have been purposely

avoided.

Although this edition of the glossary is based principally on current Forest

Service terminology, other public and private agencies concerned with protect'

ing forest land from fire have been consulted in an effort to reflect the widest

current usage of forest fire terminology.

Finally, the ultimate purpose of this glossary is to improve accuracy in the

exchange of thought concerning forest-fire control. Unless those engaged in

forest'-fire work use these terms precisely, that purpose cannot be accomplished.

This handbook supersedes an unnumbered publication of the same title,

issued April 1939.

Washington, D. C. August 1956

For sale by the Superintendent of Documents, U. S. Government Printing Office

Wiishinçton 25, D. Ç. - Price 15 cents
Glossary of Terms Used in

Forest Fire Control

Prepared by the Forest Service

Actionable fire. (1) A fire started or allowed to spread in violation

of any law, ordinance, or regulation; (2) any fire that requires

suppression.

Air freight. All items for transport and dehvery entirely by aircraft

from airfield to airfield or heliport to heliport.

Air-ground detection. A fire detection system combining fixed

coverage of key areas by ground detectors with aerial patrol varied

according to needs.

Air officer. A person responsible as a staff officer for establishing

and operating aerial service on a going fire. Is responsible for the

effectiveness of such service and for conformance with applicable

regulations and instructions. He is directly supervised by the fire

boss, service chief, or camp boss.

Alidade. A straightedge equipped with sights; an essential part of

a device for locating fires.

Allowable burned area. The maximum average loss in acreage

burned for a given period of years that is considered acceptable

under organized fire control for a given area.

Anchor point. An advantageous location, usually a barrier to fire

spread from which to start constructing fireline. Used to minimize the chance of being fianked by the fire while the line is being

constructed.

Area ignition. The ignition of a number of individual fires throughout an area either simultaneously or in quick succession, and so

spaced that they soon infiuence and support each other to produce

fast, hot spread of fire throughout the area. See Simultaneous

ignition.

Area needing protection. Any area in which fires are likely to

start and spread and do sufficient damage to justify organized fire

control.

Attack a fire. Limit the spread of fire by cooling, smothering, or

removing or otherwise treating the fuel around its perimeter. See

Direct method, Indirect method. Parallel method.

Attack time. See Elapsed time.

3
Azimuth. Direction from a point, measured in degrees clockwise

from true north.

Azimuth circle. A circle graduated in degrees in a clockwise

direction.

Back azimuth. Azimuth plus 180°; direction opposite to azimuth.

Back-burn. Used in some localities to specify fire set to spread

against the wind in prescribed burning. Also called backfire.

Backfire. (1) Fire set along the inner edge of a fire control line to

stop a spreading wildfire by reducing the fuel or changing the

direction of force of the fire's convection column. The term applies

best where skilled techniques are required for successful execution.

Using such fire to consume unbumed fuel inside the fireline to

speed up line holding and mopup is usually distinguished as "burning out'' or ''clean burning." (2) A prescribed fire set to burn

against the wind. Also called back-biu:n. (3) To set a backfire.

Barrier. Any obstruction to the spread of fire. TypicaUy, an area

or strip devoid of flammable fuel.

Base camp. See Fire camp.

Berm. Outside or downhill side of a ditch or trench.

Blind area. An area in which neither the ground nor its vegetation

can be seen from a given observation point under favorable atmospheric conditions.

Block plan. A detailed prescription for treating a given burning

block with fire.

Blowup. Sudden increase in fire intensity or rate of spread sufficient

to preclude direct control or to upset existing control plans. Often

accompanied by violent convection and may have other characteristics of a fire storm.

Board of review. A board or committee selected to review results

of fire control action on a given xmit or the specific action taken

on a given fire in order to identify reasons for both good and poor

action, and to recommend or prescribe ways and means of doing a

more effective and efficient job.

Breakover. A fire edge that crosses a control line or natural barrier

intended to confine the fire. Also called slopover.

Breakover fire. A fire resulting from a breakover, particularly as

applied to a fire that breaks out after abandonment or being

declared out.

Broadcast burning. Intentional burning in which fire is intended

to spread over all of a specific area. It may or may not qualify

as prescribed burning.
Brush. Shrubs and stands of short scrubby tree species that do not

reach merchantable size. (Not a synonym for Slash or Reproduction.)

Buildup. 1. Cumulative effects of drying (during a preceding period) on the current fire danger. 2. Acceleration of a fire with time.

3. Increase in strength of a fire control organization.

Burning block. In prescribed burning, an area having sufficiently

uniform stand and fuel conditions to be treated uniformly under a

given burning prescription. The size ranges from the smallest that

allows an economicaUy acceptable cost per acre up to the largest

that can conveniently be treated in one burning period.

Burning conditions. The state of the combined factors of environment that affect fire in a given fuel association.

Burning index. A number in an arithmetic scale determined from

fuel moisture content, wind speed, and other selected factors that

affect burning conditions and from which ease of ignition of fires

and their probable behavior may be estimated. See Danger index.

Burning index class. A segment of a burning index scale identified

by such qualitative terms as low, medium, high, very high, or

extreme or by numerals 1, 2, 3, 10.

Burning index meter. A device used to determine burning index

for different combinations of burning index factors.

Burning out. Setting fiire inside a control line to consume fuel

between the edge of the fire and the control line. Also called

firing out or clean burning. See Backfire.

Burning period. That part of each 24-hour period when fires will

spread most rapidly. Typically, this is from 10:00 a. m. to sundown.

Calculation of probabilities. Evaluation of all existing factors

pertinent to probable future behavior of a going fire and of the

potential ability of available forces to carry out control operations

on a given time schedule.

Camp boss. A person responsible for establishing and operating a

fire camp. Directly supervised by the fire boss or the service chief

in a headquarters camp, or by a sector boss or division boss in a

line camp.

Campfire. As used to classify the cause of a forest fire, a fire that

was started for cooking or for providing hght and warmth and that

spreads sufficiently from its source to require action by a fire control agency. Usually exclusive of fires started by raikoad or lumbering employees in connection with their work. See also Causes

of fires.
Cat boss. A person responsible for supervising one or more tractor

operators and helpers to get efficient and productive use of the

machines in constructing fireline or in mopping up.

Catface. A defect on the siu-face of a tree resulting from a wound

in which healing has not reestablished the normal cross section.

See Fire scar, Fire wound.

Cat line. A fire line constructed by a tractor with a bulldozer or

scraper.

Causes of fires. For statistical purposes forest fires are grouped

into broad cause classes. The eight general causes defined in U. S.

Forest Service practice are: Campfire, Debris burning fire, Incendiary fire. Lightning fire, Lumbering fire. Railroad fire. Smoker fire,

Miscellaneous fire. See separate definition of each.

Center firing. A technique of broadcast burning in which fires are

set in the center of the area to create a strong draft. Additional

fires are then set progressively nearer the outer control lines as

indraft builds up to draw them in toward the center. See Simultaneous firing and Area ignition.

Chance. Conditions suitable for a given kind of operation, e. g.:

gravity chance, water so located that it can be delivered by gravity

to a desired point; pump chance, the quantity and location of water

with respect to a fire that is suitable for power pumps.

Checking station. A point on a main route of travel where traffic

is checked and travelers instructed as a fire-prevention measure.

Sometimes called registration station.

Class of fire (as to kind of fire).

Class A. Fire in solid fuels, including forest fires.

Class B. Fire in flammable hquids.

Class C. Fire in electrical equipment.

Class of fire (as to size of forest fires).

Class A. A fire of one-fourth acre or less.

Class B. A fire of more than one-fourth acre, but less than 10 acres.

Class C. A fire of 10 acres or more, but less than 100 acres.

Class D. A fire of 100 acres or more, but less than 300 acres.

Class E, A fire of 300 acres or more.

Clean burning. See Burning out.

Closed area. An area in which specified activities or entry are

temporarily restricted to reduce risk of man-caused fires.

Closure. Legal restriction, but not necessarily elimination, of specified activities such as smoking, camping, or entry that might

cause fires in a given area.

Coarse fuels. See Heavy fuels.

6
Cold trailing. A method of controlling a partly dead fire edge by

carefully inspecting and feeling with the hand to detect any fire,

digging out every live spot, and trenching any live edge.

Communication officer. A person responsible for installing, operating and maintaining the communication service needed when

suppressing a fire. Usually under supervision of the service chief.

Supervises communication technicians, operators, and messengers.

Condition of vegetation. Stage of growth, or degree of flammability of vegetation that forms part of a fuel complex. Herbaceous

stage is at times used when referring to herbaceous vegetation

alone. In grass areas minimum qualitative distinctions for stages

of annual growth are usually green, curing, and dry or cured.

Conflagration. A raging, destructive fire. Often used to connote

such a fire with a moving front as distinguished from a fire storm.

See Fire storm.

Constant danger. Resultant of all fire danger factors that are

relatively unchanging in a given area, e. g., values at stake, normal

risk, topography, kind of fuel, exposure to prevailing wind, etc.

See Variable danger.

Control a fire. To complete control line around a fire, any spot

fires therefrom, and any interior islands to be saved; bum out any

unburned area adjacent to the fire side of the control lines; and

cool down all hot spots that are immediate threats to the control

line, until the lines can reasonably be expected to hold under foreseeable conditions. See Suppress a fire.

Control force. Personnel and equipment used to control a fire.

Control line. An inclusive term for all constructed or natural fire

barriers and treated fire edge used to control a fire.

Control time. See Elapsed time.

Controlled burning. The planned application of fire with intent

to confine it to a predetermined area. See Prescribed burning.

Corral a fire. To surround a fire and any spot fires therefrom with

control line that becomes the ultimate fire edge.

Counter fire. Fire set between main fire and backfire to hasten

spread of backfire. Also called Draft fire. The act of setting

counter fires is sometimes called front firing or strip firing. In

European forestry is synonymous with backfire.

Cover type. The designation of a vegetation complex described by

dominant species, age, and form.

Creeping. Fire bimiing with a low flame and spreading slowly. See

Smoldering, Rimning, Spotting.

Crew boss. A person in supervisory charge of usually 5 to 30 fire

fighters and responsible for their performance, safety, and welfare

for the duration of their assignment to him. Sometimes called

foreman.
Cross shot. Intersecting lines of sight from two points to the same

object. Frequently used to determine the location of a fire from

lookouts.

Crown fire. A fire that advances from top to top of trees or shrubs

more or less independently of the surface fire. Sometimes crown

fires are classed as either running or dependent, to distinguish the

degree of independence from the surface fire. See Crown out.

Crown out. Fire burning principally as a siurface fire that intermittently ignites the crowns of trees or shrubs as it advances.

Crowning. Fire advancing from crown to crown of trees or shrubs.

Danger board. A device to display a rating of the variable fire

danger and the values of the factors on which the rating is based.

Danger class. A segment of a fire danger scale identified by a

qualitative or numerical term.

Danger index. A relative number indicating the severity of forest

fire danger as determined from burning conditions and other variable factors of fire danger. See Burning index.

Danger meter. A device for combining ratings of several variable

factors into numerical classes or ratings of fire danger.

Debris burning ñre. A fire spreading from any fire originally set

for the purpose of clearing land, or for rubbish, garbage, range,

stubble, or meadow burning. (This does not include incendiary

fires, lumbering fires, or hazard reduction on rights-of-way of

common-carrier raihoads.)

Detection. The act or system of discovering and locating fires.

Difläculty of control. See Resistance to control.

Direct attack. See Direct method.

Direct method. A method of suppression that treats the fire as a

whole, or all its burning edge, by wetting, cooling, smothering, or

chemically quenching the fire or by mechanically separating the

fire from unburned fuel.

Discovery. Determination that a fire exists. In contrast to detection, location of a fire is not requhed.

Discovery time. See Elapsed time.

Dispatcher. A person who receives reports of discovery and status

of fires, confirms their location, takes action promptly to provide

the men and equipment likely to be needed for control in first

attack, and sends them to the proper place. For additional needs,

he acts on orders from the fire boss.

Dispatcher's meter. A device that gives for specific fuel types the

strength of attack required to control a fire within specified speed

of attack time standards.

8
Division. A unit of a complex fire perimeter between designated

relief, drainage, or cultural features organized into two to four

sectors for control. Usually so planned that it can be personally

and completely inspected by the division boss twice per shift.

Division boss. A supervisory staff member responsible for all suppression work on a fire division under general instructions from

the fire boss, or Hne boss acting for him.

Drift smoke. Smoke that has drifted from its point of origin and

has lost any original billow form.

Dry lightning storm. A lightning storm with negligible precipitation reaching the ground.

Duflf. The partly decomposed organic material of the forest floor

beneath the litter of freshly fallen twigs, needles, and leaves. See

Litter.

Economic theory. A theory of forest fire control which postulates

that the object of control is to keep total cost (prevention plus

presuppression plus suppression plus damage) to a minimum.

(Abbreviated as minimum P+P+S+D, or least cost, or least cost

and damage.) See Minimum-damage theory.

Edge firing. A technique of broadcast burning in which fires are set

along the edges of an area and allowed to spread to the center.

Elapsed time. Total time used to complete any given step or steps

in fire suppression. The basic steps are listed chronologically below.

(See local administrative instructions for combinations used in reporting practice.)

DISCOVERY TIME. Elapsed time from start of fire (known or estimated) imtil the time of the first discovery that results directly

in suppression action.

REPORT TIME. Elapsed time from discovery of a fire until the

first man who does effective work on the fire is notified of its

existence and location.

GETAWAY TIME. Elapsed time from report of a fire to the man

who does first effective work on it until he starts to it.

TRAVEL TIME. Elapsed time from beginning of actual travel by

the first man doing effective work on a fire until he begins

work on the fire.

CORRAL TIME. Elapsed time from first work on a fire by the

man who does first effective work until ultimate perimeter of

fire is established by control line. (Now seldom used.)

CONTROL TIME. Elapsed time either from first work on a fire or

from corral of a fire until holding the control line is assured.

Mopup TIME. Elapsed time from time of control until the end

of organized mopup.

PATROL TIME. Elapsed time from completion of organized mopup

until a fire is declared out.
Ëiapsèd timé staïidardâé Matímuín ainoünts of time allowed by

administrative rule for given steps of fire suppression.

Equipment officer. A person responsible for managing and servicing tools and mechanical equipment (except aerial) and pack stock

needed when suppressing a fire. Supervised by service chief.

Supervises equipment, service-men, transportation operators, and

packers.

Extra-period fire. A fire not controlled by 10 a. m. of the day

following discovery.

Fag station. See Smoke here.

False alarm. A reported smoke or fire requiring no suppression,

e. g., brush burning under control, mill smoke, false smoke. See

False smoke.

False smoke. Any phenomenon likely to be mistaken for smoke,

such as gray cliffs, sheep driveway or road dust, or fog.

Feeling for fire. Examining biu*ned material after fire is apparently

out and feeling with bare hands to find any live coals.

Fine fuels. See Flash fuels.

Fingers of a fire. The long narrow tongues of a fire projecting from

the main body.

Fire behavior. The manner in which fuel ignites, flame develops,

and fire spreads and exhibits other phenomena.

Fire boss. The person responsible for all suppression and service

activities on a fire. Primary responsibilities are to develop control plans and organize and direct the fire suppression organization

in such manner that the fire is completely and efläciently controlled.

May carry out all responsibilities alone or assign prescribed line

and staff duties to subordinates.

Firebreak. A natural or constructed barrier utilized to stop or check

fires that may occm* or to provide a control line from which to work.

Sometimes called a fire lane.

Fire camp. A camp used to accommodate men and equipment while

suppressing a fire. Also called base camp, side camp, or fly camp,

depending on location and fimction.

Fire concentration. A situation in which numerous fires are burning in a locality. Also used at times to denote the rate of fire

occurrence per unit of area.

Fire-control. All activities to protect wild land from fire. (Includes

prevention, presuppression, and suppression.) See also Control a

fire.

Fire-control equipment. All tools, machinery, special devices, and

vehicles used in fire control, but excluding structures.

10
Fire control improvements. The structures primarily used for fire

control, such as lookout towers, fireguard cabins, telephone lines

and roads to lookout stations, etc.

Fire control planning. The systematic technological and administrative management process of designing organization, facilities,

and procedures to protect wild land from fire.

Fire cooperator. A local person or agency who has agreed in advance to perform specified fire control services and who has received

advanced training or instructions in giving such service. Also

called cooperator, planned cooperator, fire warden, fire agent, per

diem guard, etc.

Fire damage. The loss, expressed in money or other units, caused

by fire. Includes all indirect losses, such as reduction in future

values produced by the forest area, as well as direct losses of cover,

improvements, wildlife, etc., killed or consumed by fire.

Fire danger. Resultant of both constant and variable fire danger

factors, which affect the mception, spread, and difficulty of control

of fires and the damage they cause. See Constant danger and

Variable danger.

Fire danger board. See Danger board.

Fire danger class. See Danger class.

Fire danger meter. See Danger meter.

Fire danger rating. A fire control management system that integrates the effects of selected fire danger factors into one or more

qualitative or nimierical indices of current protection needs. See

Fire danger.

Fire edge. The boundary of a fire at a given moment.

Fire effects. Any consequence—neutral, detrimental, or beneficial—

resulting from fire.

Fire foam. See Foam.

Fireguard. A general term for firemen, lookout men, fire patrolmen,

and others employed for prevention, detection, and suppression of

fires. See Short-term.

Fireline. The part of a control hne that is scraped or dug to mineral

soil. Sometimes called fire traU. See Control line.

Fireman. A person whose principal function is fire suppression.

Also called Smokechaser.

Fire pack. A one-man unit of fire tools, equipment, and supplies

prepared in advance to be carried on the back.

Fire-progress map. A map maintamed on a large fire to show at

given tunes the location of the fire, deployment of suppression

forces, and progress of suppression.

11
Fireproof. 1. Not burnable. 2. To treat an area, hazard, road,

etc., so as to reduce the danger that fires will start or spread, e. g.,

to fireproof a roadside or campground.

Fire protection. See Fire control.

Fire retardant. Any substance that by chemical or physical action

reduces flammability of combustibles.

Fire safety ofíicer. A staff person responsible for identifying the

accident and health hazards to fire suppression forces and for

advising the fire boss on means of keeping them at a minimum.

Fire scar. 1. A healing or healed injury or wound, caused or accentuated by fire, on a woody plant. See Fire wound, Catface. 2.

The scar made on a landscape by fire.

Fire season. The period or periods of the year dm*ing which fires

are likely to occur, spread, and do sufi&cient damage to warrant

organized fire control.

Fire storm. Violent convection caused by a large continuous area

of intense fire. Often characterized by destructively violent surface indrafts near and beyond the perimeter, and sometimes by

tornadolike whirls.

Fire suppression organization. 1. The management structure

designed to enable carrying out line and staff duties of the fire

boss with increases in size and complexity of the suppression job.

2. All supervisory and facilitating personnel assigned to fire suppression duty under the direction of a fire boss.

Fire-tool 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 trail. See Fire line.

Fire trap. 1. An accumulation of highly flammable fuel. 2. A

situation in which it is highly dangerous to fight a fire.

Fire warden. An officer in charge of fire control in a given area.

Fire-weather forecast. A weather prediction specially prepared

for use in forest fire control.

Fire-weather station. A forest meteorological station specially

equipped to measure weather elements that have an important

effect on fire control.

Fire wound. Fresh or healing injuries of the cambium of a woody

plant caused by fire. See Fire scar.

Firing out. See Burning out.

First-work period. The time between discovery of a fire and 10

a. m. of the following calendar day. Also called Initial shift.

Succeeding work periods are 24 hours beginning at 10 a. m.

12
First attack. The first suppression work on a fire.

Flammability. The relative ease with which fuels ignite and burn

regardless of the quantity of the fuels. Preferred to "inflammabüity.''

Flank fire. A fire set along a control line parallel to the wind and

allowed to spread at right angles to it.

Flanking. Attacking a fire by working along the flanks either

simultaneously or successively from a less active or anchor point

and endeavoring to connect the two lines at the head.

Flanks of a fire. The parts of a fire's perimeter that are roughly

parallel to the main direction of spread. See also Parts of a fire.

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. Also called fine fuels. See Heavy

fuels.

Foam. A chemical fire-extinguishing mixture. When applied it

forms bubbles which greatly increase the mixture volume. It

adheres to the fuel, and reduces combustion by cooling and moistening and by excluding oxygen.

Followup. The act of supporting the first man or men who go to a

fire by sending additional men or equipment to facilitate suppression. Sometimes called Reinforcement.

Forced burning. See Simultaneous ignition.

Forest fire. Any wild-land fire not prescribed for the area by an

authorized plan.

Forest protection. Prevention and control of any cause of potential forest damage.

Free-burning. The condition of a fire or part of a fire that has not

been checked by natural barriers or by control measures.

Front firing. See Counter fire.

Fuel moisture content. The quantity of moisture in fuel expressed

as a percentage of the weight when thoroughly dried at 212° F.

Fuel-moisture-indicator stick, A specially prepared stick or set

of sticks of known dry weight continuously exposed to the weather

and periodically weighed to determine changes in moisture content, as an indication of moisture changes in forest fuels.

Fuel reduction. See Hazard reduction.

Fuel type. An identifiable association of fuel elements of distinctive species, form, size, arrangement, or other characteristics that

will cause a predictable rate of fire spread or difficulty of control

under specified weather conditions.

13
Fuel type classification. The division of forest areas into units

according to their characteristics with respect to rate of spread and

difficulty of estabUshing and holding control line.

Functional method. See Progressive method.

Getaway time. See Elapsed time.

Going fire. A current fire during the period between time of start

and being declared out.

Gridiron. To search for a small fire by systematically traveling

over an area on parallel courses or grid lines.

Ground fire. Fire that consumes the organic material beneath the

surface litter of the forest floor, e. g., a peat fire.

Gutter trench. A ditch dug on a slope below a fire, designed to

catch rolling burning material.

Hangover fire. See Holdover fire.

Hazard. A fuel complex defined by kind, arrangement, volume,

condition, and location that forms a special threat of ignition or of

suppression difficulty.

Hazard reduction. Any treatment of a hazard that reduces the

threat of ignition and spread of fire.

Hazemeter. An instrument for measuring the dependable range of

distance at which a standard smoke column can be detected by the

eye under existing conditions of haze. Also called visibihty meter.

Head fire. A fire spreading or set to spread with the wind.

Head of a fire. The most rapidly spreading portion of a fire's

perimeter, usually to the leeward or up slope. See also Parts of a

fire.

Heavy fuels. Fuels of large diameter such as snags, logs, and large

limbwood, which ignite and are consumed more slowly than flash

fuels. Also called coarse fuels. See Flash fuels.

Held line. All worked control line that still contains the fire when

mopup is completed. Excludes lost line, natural barriers not backfired, and unused secondary lines.

Heliport. A permanent or semipermanent base for heUcopters.

Helispot. A temporary landing spot for hehcopters.

Herbaceous stage. See Condition of vegetation.

Holdover fire. A fire that remains dormant for a considerable time.

Also called hangover fire or sleeper fire.

Hose-lay. The 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. See Progressive hose-lay,

Simple hose-lay.

14
Ëtotsiiot crew. An intensively trained ôre-figliting crew used primarily as followup for first attack forces.

Hotspot. A particularly active part of a fire.

Hotspotting. Checking the spread of fire at points of more rapid

spread or special threat. Is usually the initial step in prompt control with emphasis on first priorities.

Hour control. A time standard applied in fire control planning

which specifies the maximum allowable time, usually from origin of

a fire to the first attack on it, that should insure a burned acreage

within the acceptable maximum for a given unit or cover type.

Incendiary fire. A fire willfully set by anyone to burn vegetation

or property not owned or controlled by him and without consent of

the owner or his agent.

Independent action. Suppression action by other than the regular

fire control organization or cooperators.

Indirect attack. See Indirect method and Parallel method.

Indirect method. A method of suppression in which the control

line is located along natural firebreaks, favorable breaks in topography, or at considerable distance from the fire and the intervening

fuel is backfired or bm^ned out. The strip to be backfired is wider

than in the parallel method and usually allows a choice of the time

when the backfiring wül be done.

Individual-assignment method. A system of organizing men to

control a fire's perimeter in which each crewman is assigned a specific

section of control line where he is responsible for all suppression

jobs from hotspotting to mopup.

Inflammability. See Flammability.

Information ofl&cer. A staff officer in a fire suppression organization responsible for information releases to the public on a fire

situation.

Initial attack. See First attack.

Initial shift. See First-work period.

Intelligence ofl&cer. A staff officer in a fire suppression organization who is responsible for gathering and compiling all information

needed to develop a suppression plan for the control of a fire.

Jump spot. A selected landing area for smokejumpers.

Knock down. To reduce the flame or heat on the more vigorously

burning parts of a fire edge.

Least-cost theory. See Economic theory.

Legitimate smoke. Smoke from any authorized use of fire as in

locomotives, industrial operations, permitted debris burning, etc.

Light burning. Periodic broadcast burning to prevent acciunulation of fuels in quantities that would cause excessive damage or

difficult suppression in the event of accidental fires.

15
Lightning fire. A fire caused directly or indirectly by lightning.

Line boss. A supervisory officer in a fire suppression organization

responsible for executing the fire suppression plan adopted by the

fire boss. Employed in some stages of organization of large forces.

May act as coordinator between two or more divisions or may

supervise three to four sector bosses if no divisions have been

established.

Line scout. A scout in a fire suppression organization assigned to

scouting duties on the fireline. See Scout.

Litter. The top layer of the forest floor, composed of loose debris

of dead sticks, branches, twigs, and recently fallen leaves or needles, little altered in structure by decomposition. See Duff.

Live burning. Progressive bm-ning of green slash as it is cut. See

Progressive burning.

Lookout. 1. A person designated to detect and report fires from a

vantage point. 2. A lookout station.

Lookout-dispatcher. A person having the combined fimction of

lookout man and dispatcher.

Lookout-fireman. A person having the combined function of

lookout man and fireman.

Lookout house. A building containing Uving quarters with walls

largely of glass, on a tower or natural elevation to permit an unobstructed view.

Lookout man or Lookout observer. A person at a lookout station

employed to detect and report fires. Called towerman in some

localities with flat relief.

Lookout observatory. Same as Lookout house defined above, but

may not contain living quarters.

Lookout-patrolman. A person who travels ridges and other vantage points to discover, locate, report, and suppress fires. Often

combines this function with prevention activities.

Lookout point. A vantage point selected for fire detection.

Lookout station. A location and associated structures for detecting

and reporting fires.

Lookout tower. A structiu-e to enable a person to be above nearby

obstructions to sight. It is usually capped by either a lookout

house or observatory.

Lumbering fire. A fire except one caused by smokers, resulting

from lumbering. (Lumbering includes all activities connected with

the harvesting or processing of wood for use or sale. Lumbering

fires include those caused by logging raihoads which are not common carriers.) See Causes of fires.

Man-passing-man method. A system of organizing men in fire

suppression in which each crewman is assigned a specific task such

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as clearing or digging fire line on a specific section of the control

line, and when that task is completed he passes other workers in

moving to a new assignment.

Maps and records ofläcer. A staff officer in a fire suppression

organization responsible for preparing administrative records of

control of a fire such as disposition of men and equipment, instructions issued, progress maps, and organization charts.

Minimum-damage theory. A theory of forest fire control which

postulates that the objective is to keep fire damage at a minimum.

See Economic theory.

Miscellaneous fire. A fire of known cause that cannot be properly

classified under any of the other seven standard causes. See Causes

of fires.

Mopup. The act of making a fire safe after it is controlled, such

as extinguishing or removing burning material along or near the

control line, felling snags, trenching logs to prevent rolling, etc.

Mopup time. See Elapsed time.

Moveup method. See Progressive Method.

Net fire effects. The sima of aU effects, both detrimental and beneficial, residting from burning.

Nonstatistical fire. In U. S. Forest Service practice, any fire that

does not qualify for inclusion in national statistical summaries of

fires. Representative examples are as follows:

(a) Fires that have gone out naturally when reached.

(b) Railroad fires confined to the right-of-way that do not endanger Forest Service-protected land and are suppressed by

railroad employees with or without Forest Service help.

(c) Small fires resulting from legitimate slash or debris burning

operations and extinguished by the causative agency.

(d) Abandoned campfires that because of the condition of forest

fuels or weather conditions cannot spread, or are confined to

improved fireplaces or stoves.

(e) Individual incendiary sets when all sets bum together and are

suppressed as one fire. In this event aU sets will be reported

as one fire.

Individual Hghtning fires set at the same time in proximity to

each other that burn together and are suppressed as one fire.

In this event only one fire will be reported.

(f) Individual incendiary sets that are suppressed separately,

where less than Yi mile intervenes between any two adjacent

sets. Only one fire will be reported for any such sets.

Individual Hghtning fires set at the same time in proximity

to each other (less than M mile apart) that are suppressed

separately. Only one fire will be reported for any such sets.

(g) Burning buildings, automotive equipment, haystacks, sawdust piles, etc., that under the prevailing conditions are not a

menace to Forest Service-protected land.

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(h) Fires from any cause, confined to private lands, that do not

endanger Forest Service-protected lands and are suppressed

by landowners or others responsible for their suppression

with or without Forest Service aid.

See Statistical fires.

Normal fire season. 1. A season in which weather, fire danger, and

number and distribution of fires are about average. 2. Period of

the year that normally comprises the fire season.

One-lick method. See Progressive method.

Panoramic photograph. Photographs from a lookout point,

bearing azimuth and vertical angle scales, to assist in locating fires

with a firefinder.

Para-cargo. Anything intentionally dropped or intended for dropping from any aircraft by parachute, other retarding devices, or

free fall.

Parallel method. A method of suppression in which firehne is constructed approximately parallel to, and just far enough from the

fire edge to enable men and equipment to work effectively, though

the line may be shortened by cutting across unbumed fingers. The

intervening strip of unburned fuel is normally burned out as the

control line proceeds, but may be allowed to bum out unassisted

where this occurs without undue delay or threat to the line.

Parts of a fire. On typical free-burning fires the spread is uneven,

with the main spread moving with the wind or up slope. The most

rapidly moving portion is designated the head of the fire, the adjoining portions of the perimeter at right angles to the head are known

as the flanks, and the slowest moving portion is known as the rear.

Patrol. 1. To travel a given route to prevent, detect, and suppress

fires. 2. To go back and forth watchfully over a length of control

line, during or after its construction, to prevent breakovers, control

spot fires, or extinguish overlooked hotspots.

Patrol time. See Elapsed time.

Piling and burning. Piling lopped slash resulting from logging,

and subsequently burning the individual pues.

Plans chief. A staff officer in a fire suppression organization responsible for the compilation and analysis of data needed for

developing suppression plans.

Plow line. A fireline constructed by a fireline plow, usually drawn

by a tractor.

Powersaw boss. See Saw boss.

Preparedness. 1. Condition or degree of being completely ready

to cope with a potential fire situation. 2. Mental readiness to

recognize changes in fire danger and act promptly when action is

appropriate.

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Prescribed burning. Skillful application of fire to natural fuels

under conditions of weather, fuel moisture, soil moisture, etc., that

will allow confinement of the fire to a predetermined area and at

the same time will produce the intensity of heat and rate of spread

required to accomplish certain planned benefits to one or more

objectives of silviculture, wildlife management, grazing, hazard

reduction, etc. Its objective is to employ fire scientifically to

realize maximum net benefits at minimum damage and acceptable

cost.

Presuppression. Activities in advance of fire occurrence to insure

effective suppression action. Includes recruiting and training,

planning the organization, maintaining fire equipment and fire

control improvements, and procuring equipment and supplies.

See Prevention; Suppression.

Prevention. Activities directed at reducing the number of fires that

start, including public education, law enforcement, personal contact, and reduction of fuel hazards.

Prevention guard. A guard who helps to prevent fires by contacting forest users and inspecting fire prevention measures and fire

equipment of industrial operations on the forest. Also called prevention patrolman.

Primary lookout. 1. A lookout point that must be manned to meet

planned mim'mnm visible area coverage in a given locality. For

that reason, continuous service is necessary during the normal fire

season and the lookout man usually is not sent to fires. 2. Sometimes designates the person who occupies such a station, but primary lookout man or observer is more specific in this sense.

Progressive burning. Slash disposal by burning the slash as it is

piled. Also called swamper burning.

Progressive hose-lay. A hose-lay in which double shutoff Y's are

inserted in the main line at intervals and lateral lines are run from

the Y's to the fire edge, thus permitting continuous application of

water during extension of the lay.

Progressive Method of Line Construction. A system of organizing men to build fireline in which they advance without changing

relative positions in Hne. There are two principal methods of applying the system: (1) Work is begun with a suitable space, such as

15 feet, between men. Whenever one crewman overtakes another,

all of those ahead move one space forward and resume work on

the uncompleted part of the line. The last man does not move

ahead until the work is complete in his space. Forward progress

of the crew is coordinated by a crew leader. This method of organization is variously termed moveup, stepup, bumpup, and functional. 2. Each man does one to several hcks or strokes of work

and moves forward a specified distance. The distance is determined by the number of men equipped with a given tool and the

19
number of licks needed per unit of line to complete the work for

that tool. This method is termed one-lick.

Project fire. Usually refers to a fire requiring manpower and equipment beyond the resources of the protection unit on which it

originates.

Protection boundary. The exterior boundary of an area within

which a given agency has assumed a degree of responsibility for

forest fire control. It may include land in addition to that for

which the agency has jurisdictional or contractual responsibihty.

Pump chance. See Chance.

Railroad ñre. A fire resulting from maintenance of the right-of-way

or construction or operation of a common-carrier railroad. See

Causes of fire.

Rate of spread. The relative activity of a fire in extending its

horizontal dimensions. It is expressed as rate of increase of the

total perimeter of the fire, as rate of forward spread of the fire

front, or as rate of increase in area, depending on the intended use

of the information. Usually it is expressed in chains per hour or

acres per hoiu* for a specific period in the fire's history.

Rate-of-spread meter. A device that computes probable rate of

spread of fire for different combinations of fuel moisture, wind

speed, and other selected factors.

Rear of a fire. The portion of the edge of a fire opposite the head.

Reburn. 1. Subsequent burning of an area in which fire has previously burned but has left fiammable fuel that ignites when burning

conditions are more favorable. 2. An area that has rebumed.

Reinforcement. See FoUowup.

Relative humidity. The ratio of the amount of moisture in a given

volume of space to the amount that volume would contain if it were

saturated. The ratio of the actual vapor pressure to the saturated

vapor pressure.

Report time. See Elapsed time.

Resistance to control. The relative difficulty of constructing and

holding a control line as affected by resistance to fine construction

and by fire behavior. Also called difficulty of control. See Resistance to line construction.

Resistance to line construction. The relative difficulty of constructing control fine as determined by the fuel, topography, and

sou. See Resistance to control.

Risk. 1. The chance of fire starting as determined by the presence

and activity of causative agents. 2. A causative agent.

Rough. The accumulation of hving 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 pme types.

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Bough reduction. Reduction of the hazard from the rough. See

Hazard reduction, Rough.

Banning. Behavior of a fire spreading rapidly with a well-defined

head. See Smoldering, Creeping, Spotting.

Saw boss. A supervisory oflicer in a fire suppression organization

responsible for the activities of saw crews (using hand or power

saws) in cutting snags or logs on a fire or part of a fire.

Scorchline. Average heights of foliage browning caused by a fire.

Scout. A staff worker in a fire suppression organization assigned

duties of gathering and reporting timely information such as

existing location and behavior of a fire, progress in control, and

the physical conditions that affect the planning and execution of

the suppression job.

Scratch line. An unfinished preliminary control line hastily established or constructed as an emergency measure to check the spread

of a fire.

Secondary lookout. 1. A lookout point used to supplement the

visible area coverage of the primary lookout system when required

by fire danger, poor visibility, or other factors. 2. Sometimes designates the person who occupies such a station, but secondary lookout

man is more specific in this sense.

Sector. A designated segment of fire perimeter or control line comprising the suppression work unit for two or more crews under one

sector boss.

Sector boss. A staff officer responsible for all suppression activities

on a specific sector of a fire.

Seen area. See Visible area.

Seen-area map. See Visible-area map.

Service chief. A staff officer in a fire suppression organization

responsible for procuring, maintaining, and distributing men,

equipment, supplies, and facilities at the times and places specified

by the suppression plan for the fire.

Set. 1. An individual incendiary fire. 2. The point or points of

origin of an incendiary fire. 3. Material left to ignite an incendiary

fire at a later time. 4. Individual Ughtning or railroad fires, especially when several are started within a short time. 5. Burning

material at the points deliberately ignited for backfiring, slash biu-ning, prescribed burning, and other purposes.

Severity index. A number that indicates the relative net cumulated

effects of daily fire danger on the fire load for an area during a

selected period, such as a fire season.

Short-term. Persons or work for which employment is less than

12 months. (Excludes fire fighters hired for a particular fire.) In

Federal service short-term appointments are usually to the position

of Fire Control Aid.

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Side camp. See Fire camp.

Simple hose-lay. A hose-lay consisting of consecutively coupled

lengths of hose without laterals. The lay is extended by inserting

additional lengths of hose in the line between pump and nozzle.

Simultaneous ignition. A technique of broadcast burning or

backfiring by which the fuel on an area to be burned is ignited

at many points simultaneously and the sets are so spaced that each

receives timely stimulation by radiation from the adjoining sets.

By such techniques, all burn together quickly and a hot, clean

burn is possible under unfavorable burning conditions where single

sets would not spread. See Area ignition.

Slash. Debris left after logging, pruning, thinning, or brush cuttmg.

It includes logs, chunks, bark, branches, stumps, and broken

understory trees or brush.

Slash disposal. Treatment of slash to reduce the fire hazard or for

other purposes. (Preferred to Brush disposal.)

Sleeper fire. See Holdover fire.

Slopover. See Breakover.

Smoke candle. A pyrotechnical product that gives smoke with

uniform color like that of a small fire and at a standard rate.

Smokechaser. See Fireman.

Smoke haze. Haze caused by smoke alone and not by water vapor,

dust, or other particles.

Smoke here. A signed spot where smoking is permitted in an area

that in general is closed to smoking. Sometimes called fag station.

Smokejumper. A fire fighter who travels to fires by aircraft and

parachute.

Smoker fire. A fire caused by a smoker's matches, or by burning

tobacco in any form. See Causes of fires.

Smoldering. Behavior of a fire burning without flame and barely

spreading. See Creeping, Running, Spotting.

Snag. A standing dead tree or part of a dead tree from which at

least the leaves and smaller branches have fallen. Often called

stub, if less than 20 feet tall.

Span of control. The maximum number of subordinates who can

be directly supervised by one person without loss of efficiency. In

fire suppression the number varies by activity, but is usually in

the general range of 3-8.

Speed of attack. Elapsed time from origin of a fire to arrival of

the first suppression force.

Spike camp. See Fire camp.

Spot burning. A modified form of broadcast slash burning in which

only the greater accumulations are fired and the fire is confined

to these spots.

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Spot fire. Fire set 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.

Standby crew. A group of men especially organized, trained, and

placed for quick suppression work on fires.

Statistical ñre. In U. S. Forest Service practice, a fire that is

suppressed wholly or in part by Forest Service employees or cooperators and on which suppression work is done either to prevent the fire from spreading to or burning over national forest or

other lands for which the Forest Service assumes protection responsibility. See Nonstatistical fires.

Stepup method. See Progressive method.

Straw boss. A working leader responsible for efficient and productive work of usually 3 to 8 fire fighters.

Strength of attack. The number of men and machines with which

a fire is attacked.

Strip burning. 1. Setting fire to a narrow strip of fuel adjacent to

a control line and then burning successively wider adjacent strips

inside as the preceding strip burns out. Also called Strip firing.

2. Burning only a relatively narrow strip or strips of slash through a

cutting unit and leaving the remainder.

Strip firing. See Strip burning.

Supply officer. A person responsible for supplying and distributing

the supplies and equipment needed to suppress a fire and for servicing tools and simple equipment. Supervised by the service chief.

Suppress a fire. Extinguish a fire or confine the area it burns within

fixed boundaries.

Suppression. All the work of extinguishing or confining a fire beginning with its discovery. See Fire control. Prevention, Presuppression.

Suppression crew. Two or more men stationed at a strategic location, either regularly or in emergency, for initial action on fixes.

Duties are essentially the same as those of individual firemen.

Suppression foreman. A man in charge of a suppression crew.

Suppression squad. See Suppression crew.

Surface fire. Fire that burns surface litter, other loose debris of the

forest floor, and small vegetation.

Swamper. An axman who cuts and clears away brush, and hmbs

small trees and down timber, that can be cleared with an ax.

iSwamper burning. See Progressive burning,

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Tanker boss. A person in a fire suppression organization responsible for supervising usually 3 to 5 tanker units to get efficient and

productive use of water in either direct attack or mopup work on

fires.

Test fire. A controlled fire set to evaluate such things as fire behavior, detection performance, control measures, etc.

Towerman. A lookout man stationed at a tower.

Travel tirae. See Elapsed time.

Travel-time map. A map showing the length of time required to

reach various parts of an area by a fireman or crew from specified

locations.

Trench. Formerly used as synonym for ''fireline," which is preferred. See Gutter trench.

Undercut line. A fireline below a fire on a slope. Also called underslung line.

Variable danger. Resultant of all fire danger factors that vary from

day to day, month to month, or year to year, e. g., weather, fuel

moisture, foliage growth and condition, variable man-caused

hazard, and variable risks of ignition. See Constant danger.

Vegetation stage. See Condition of vegetation.

Visibility distance. Maximum distance at which a smoke column

of specified size and density can be seen and recognized as a smoke

by the unaided eye. See Visual range.

Visible area. The ground or vegetation thereon that can be directly

seen from a given lookout point under favorable atmospheric conditions.

Visible area map. A map showing the specific territory in which

either the ground surface or the vegetation growing thereon is

directly visible, to practical distances, from a lookout point.

Visual range. Maximum distance at which a given object can just

be seen by an observer with normal vision. See Visibility distance.

Water-supply map. A map showing location of suppUes of water

readily available for pumps, tanks, trucks, camp use, etc.

Wet water. Water with added chemicals, caUed wetting agents, that

increase its spreading and penetrating properties.

Wetting agent. A chemical that reduces the surface tension of

water and causes it to spread and penetrate more effectively.

Wildfire. 1. An unplanned fire requiring suppression action, as

contrasted with a prescribed fire burning within prepared lines

enclosing a designated area, imder prescribed conditions. 2. A

free-burning fire unaffected by fire suppression measures.

Wild land. Uncultivated land, excepting fallow lands.

Wood cylinders. See Fuel-moisture-indicator sticks.

U. S. MVERNMENT PRINTING OTriCE 889820

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