Glossary of firefighting

Firefighting jargon includes a diverse lexicon of both common and idiosyncratic terms. One problem that exists in trying to create a list such as this is that much of the terminology used by a particular department is specifically defined in their particular standing operating procedures, such that two departments may have completely different terms for the same thing. For example, depending on whom one asks, a safety team may be referred to as a standby, a RIT or RIG or RIC (rapid intervention team/group/crew), or a FAST (firefighter assist and search team). Furthermore, a department may change a definition within its SOP, such that one year it may be RIT, and the next RIG or RIC.

The variability of firefighter jargon should not be taken as a rule; some terms are fairly universal (e.g. stand-pipe, hydrant, chief). But keep in mind that any term defined here may be department- or region-specific, or at least more idiosyncratic than one may realize.

A

3D zone control: The strategy of 3D zone control intended to improve the safety of firefighters operating inside a burning structure. It attempts to safeguard the immediate locality of any space occupied by firefighters in resorting to various defensive actions that (a) confine the fire; (b) remove combustion products safely and effectively; or (c) mitigate dangers in the hot-gas layers. The overall tactical objective is to provide more permanent levels of protection in structural compartments (safe zones), from which firefighters may operate in various fire & rescue roles.
A-side: "Alpha" side, Front of the fire building, usually front door facing street, side with visible address but may be facing parking area where first apparatus arrives; other sides labeled B (left), C (rear), D (right) in a clockwise manner, as necessary when speaking of or staffing structure fire sectors.
Above-ground storage tank: Storage tank that is not buried. Compare underground storage tank. Unburied tanks are more prone to physical damage, and leaks are released to the air or ground, rather than the soil surrounding a buried tank.
Accelerant: flammable fuel (often liquid) used by some arsonists to increase size or intensity of fire. May also be accidentally introduced when HAZMAT becomes involved in fire.
Accountability: The process of emergency responders (fire, police, SAR, emergency medical, etc.) checking in with or announcing to an incident commander or accountability officer that they have arrived on scene of an incident. Through the accountability system, each person is tracked throughout the incident until released from the scene by the incident commander or accountability officer. During an extended operation, an accountability "roll-call" may be performed at specified intervals. This is becoming a standard in the emergency services arena primarily for the safety of emergency personnel. This system may implement a name tag system or personal locator device (tracking device used by each individual that is linked to a computer).
AFA: Automatic fire alarm/actuating fire alarm/activated fire alarm
Aircraft rescue and firefighting (ARFF): a special category of firefighting that involves the response, hazard mitigation, evacuation and possible rescue of passengers and crew of an aircraft involved in an airport ground emergency.
Air-track: The route by which the air enters the structure to the fire and the subsequent path the heated smoke takes to exit the structure. Also referred to as flow path.
Active Service Firefighter (China): A defunct term used prior to 2018 for firefighters, who were People's Armed Police personnel and were treated as military personnel.
Alarm: (1) system for detecting and reporting unusual conditions, such as smoke, fire, flood, loss of air, HAZMAT release, etc.; (2) a specific assignment of multiple fire companies and/or units to a particular incident, usually of fire in nature; (3) centralized dispatch center for interpreting alarms and dispatching resources. See fire alarm control panel.
All companies working: Status report at fire scene indicating that available manpower is busy, and more resources may become necessary if incident is not controlled soon.
Ammonium nitrate: component of ANFO; contents of two ships that exploded in Texas City disaster, killing over 500 people, including all 27 volunteer firefighters at the scene; as well as in warehouses in the port of Beirut.
ANFO: Ammonium nitrate and fuel oil combination making a high explosive.
Apparatus (U.S.) / Appliance (U.K.): A term usually used by firefighters describing a piece of mobile firefighting equipment, such as a pumper, a tanker, a ladder truck, etc.
Arson: the crime of maliciously (or perhaps recklessly) setting fire to property, especially a dwelling. Punishable in various degrees, depending upon the circumstances. Occasionally occurs as a psychotic act of a mentally ill firefighter.
Authority having jurisdiction (or AHJ): organization or agency with legal authority over a given type of incident (e.g., fire, EMS, SAR, arson, HAZMAT); may change or overlap as incident changes, as where fire becomes arson investigation once danger is over, or motor vehicle accident becomes police business after vehicle extrication, fire, and HAZMAT issues are complete.
Auto-aid: An enhanced form of mutual aid agreement between one or more departments or districts, under which a mutual aid response can be dispatched "automatically" without prior permission from a chief officer.
Autoextended fire: structure fire that has gone out a window or other opening on one floor and ignited materials above, on another floor or other space (attic, cockloft).
Auto ignition temperature (AIT): The temperature at which a gas/air mixture will self-ignite. As the temperature increases the lower flammable limit (LFL) will approach zero. Also known as spontaneous ignition temperature (SIT).
Available flow: total amount of water that can be put on a fire, depending upon water supply, pump size, hoses, and distance to the fire. Incident commander must assess available flow to determine whether additional apparatus or streams are required. See Fire flow requirement.

B

BA set: Breathing apparatus set consisting of a face-mask and compressed air cylinder. Two types SDBA and EDBA. SDBA or standard duration breathing apparatus has one cylinder and supplies about 30 minutes of air. EDBA or extended duration breathing apparatus has two cylinders and supplies about 60 minutes of air.
Backdraft: A fire phenomenon caused when heat and heavy smoke (unburned fuel particles) accumulate inside a compartment, depleting the available air, and then oxygen/air is re-introduced, completing the fire triangle and causing rapid combustion.
Backfiring: Also known as a "controlled burn," it's a tactic mostly used in wildland firefighting associated with indirect attack, by intentionally setting fire to fuels inside the control line. Most often used to contain a rapidly spreading fire, placing control lines at places where the fire can be fought on the firefighter's terms. This technique has been used in rapidly spreading urban fires, especially in San Francisco following the 1906 earthquake.
Back burning: Australian term, for backfiring, above.
Backflow preventer: Automatic valve used in hose accessories to ensure water flows only in one direction. Used in permanent fire department connections (FDC) to sprinklers and dry standpipes, as well as portable devices used in firefighting.
Backstretching: Laying a supply line from the vicinity of the fire structure to a hydrant. (Typically laid from the hydrant toward the fire on the way in.)
Bank down: What the smoke does as it fills a room, banks down to the floor, creating several layers of heat and smoke at different temperatures—the coolest at the bottom.
Bail-out. The act of completing a quick egress away from a fire room, on a ladder. This is done if flashover conditions are imminent.
Boiling liquid expanding vapor explosion (BLEVE): Explosion of a pressure tank containing an overheated material when the vapor expansion rate exceeds the pressure relief capacity (e.g., steam boiler or LPG tank). If the contents are flammable, the rapidly released vapor may react in a secondary fuel-air explosion, usually violent and spectacular.
Bomber: Australian term for fixed wing fire-fighting aircraft. Also called "water bomber" or "borate bomber".

Box (alarm): a term used to describe a preplanned response to an incident type and location, ensuring appropriate personnel and equipment are available as quickly as possible. The term is typically combined with a number identifying the specific response instructions. For example, "Box 25598" corresponded to Alvernia High School in Chicago and enumerated firefighting companies to be dispatched when an alarm from that location was received. Historically, box instructions were listed on cards and dictated by building types and geographic area. A building known to have hazardous materials will trigger deployment of HAZMAT equipment in addition to standard truck and engine companies. The box can also include escalation instructions. Modern computer-aided dispatch supports fine-grained variation to the box based on times of year, weather, or severity of incident. Incident commanders will instruct dispatchers to "fill the box" when the initial investigation of an alarm confirms a working fire and all the planned companies are necessary, or to "terminate the box" if the incident is resolved and the responding companies are no longer needed. The box term derives from the historical use of numbered fire alarm pull boxes that were commonplace in cities during the 19th and 20th Centuries.
Buffer zone: The creation of a 'buffer-zone' implies the use of 3D defensive actions to reduce potential for an ignition of fire gases in the immediate area of a structure occupied by firefighters. This may create a temporary and more local zone of safety for firefighters, although offering far less protection than a 'safe-zone'.
Buggy: A term usually used for the chief's vehicle, a reference back when the chief would respond in a horse drawn buggy. In wildland fire "buggy" is slang for "crew transport." Type I crews are referred as "Interagency Hotshot Crews" (20-21 people) that have crew transports permanently assigned to them and almost all the transports use the same model configuration with no or little differation for the different agencies that have hotshot crews. Hotshot crews have two crew transports and a superintendents vehicle, which is a pickup sized (one ton) with a utility box configuration. Hotshot crews are not the only type of crew and less experienced crews are called Type II crews that may not have vehicles permanently assigned to them. It is rare to hear a crew transport called same. Almost everyone on a wildland fire will say "buggy" instead.
Burn building: Former official US term for a live training structure. Still commonly used in the US, although the term was discontinued for official use in the US in 2007.
Bus: Another term for ambulance (NYC).
Bushfire: Australian term, for wildfire, below.

C

Call firefighter: In the U.S., call firefighters respond as needed on a part-time basis to all types of emergencies. Call firefighters train with their local engine companies in their districts. Call firefighters are used in three different ways. “First Responder" call firefighter units, are those units that are staffed entirely by paid call firefighters. These firefighters respond to all emergency incidents within their jurisdictional areas and are supported by full-time companies from adjoining jurisdictions. "Supplemental" call firefighter units are those units that staff a second engine company from a station that is also staffed by a full-time company. These units respond to all multi-unit responses in their district, and cover the station when the career companies are committed. "Augmentation" call firefighters are assigned to an existing career company and respond directly to the scene to augment that company's staffing. See also Retained firefighter (U.K.)
Can: Informal term for an air pressurized water (APW) extinguisher.
Career firefighter: (U.S.) A person whose primary employment is as a firefighter for a municipality or other agency or company and who derives the majority of his earned income working in the fire service. See also wholetime firefighter (U.K.)
Career firefighter (专职消防员): (China) The Chinese term for volunteer firefighters.
Charge a hose: To make water pressure available on a hose in final preparation for its use. This is done on the scene after the hose is deployed, but prior to entering the fire danger area. (Also known as "charge the line")
Charged hose: A hose that is filled with water and pressurized; ready to use. The charged line is much more difficult to move than one not yet charged.
Chauffeur: See Engineer.
Chief officer: An executive officer of the fire department, as contrasted with a tactical company officer. Typical chief officers include the fire chief, assistant and deputy fire chief, battalion or division or district chiefs (who may each supervise fire captains), watch commanders and the Scottish Fire Master.
Chimney fire: Fast and intense fire in a chimney flue in which accumulated creosote and other combustion byproducts ignite. These often extend fire into the roof or attic, especially with defective chimneys or when the mortar becomes hot enough to melt.
Class A: A fire involving combustibles such as wood, paper, and other natural materials. See Fire classes.
Class B: A fire involving flammable liquids such as gasoline or other fuels. See Fire classes.
Class C: An electrical fire. See Fire classes.
Class D: A fire involving metals, such as sodium, titanium, magnesium, potassium, uranium, lithium, plutonium and calcium. See Fire classes.
Class E (Europe/Australia): A composite Class A/Class B fire that is not also a Class C fire.
Class F (Europe/Australia): See Class K.
Class K: A fire involving cooking oils. Technically, this is a subclass of Class B. See Fire classes.
Cockloft: A structural space above ceiling and below rafters, often connecting adjacent occupancies and permitting fire to spread laterally, often unseen.
Collapse zone: The area around a structure that would contain debris if the building were to collapse. This is generally 1.5x the height of the structure.
Combustion: When materials smolder or burn. See main article for technical details.
Commissioner: Civilian administrator of the fire services, appointed or elected in some cities, such as the New York City Fire Commissioner.
Company: A group of firefighters organized as a team, led by a fire officer, and equipped to perform certain operational functions. The firefighters in a company nearly always work on the same vehicle, though on different shifts. Compare with platoon and unit.
Company officer : A fire officer, typically a lieutenant or captain, who leads a team of two or more firefighters in a tactical company.
Compartment fire: An "Isolated" fire, or a fire which is "boxed in" or "closed off" from the rest of the structure. An example of this is a fire in a room where all the windows and doors are closed preventing the fire from spreading to other rooms.
Confined space: Usually refers to a "confined space rescue." This involves a space that may have very limited access, little or no room to maneuver, poor air or light, and very likely other hazards. A trench cave-in, a collapsed building, a sewer or utility vault rescue, or a problem in and around industrial equipment are some examples.
Conflagration: A large, typically urban, fire involving numerous structures; loosely defined as enveloping an area equivalent to one or more square blocks. Compare with firestorm.
Contained Fire: A fire restricted to boundaries established by fire fighters.
Crash tender: A pump capable of spraying foam used at airports.
Crew resource management (CRM): Training developed by NASA based on the concept that the primary cause of the majority of aviation accidents is human error and problems with interpersonal communication in particular. The training has been adapted for the fire service and teaches firefighters the correct way to question orders on an emergency scene. It also helps supervisors understand that the questioning of an order should not be interpreted as a threat to their authority.
Cross lay: Arrangement of hose on a pumper such that it can be quickly unloaded from either side of the apparatus; often pre-connected to a pump outlet and equipped with a suitable nozzle. Also known as Mattydale Lay.

D

Dead lay: A load of hose on a pumper, but not connected to a pump outlet. Often used for larger supply lines.
Defensive attack: A primarily exterior form of attack often used when fighting the fire directly or from within a structure is not feasible due to dangers from direct flame, heat, structural collapse or the presence of hazardous materials. Often structures which are fully involved are attacked defensively with the main goal being the protection of nearby exposures. This form of attack is far less effective than an Offensive or Direct attack. Also known as "surround and drown."
Deflagration: An explosion with a propagation front traveling at subsonic speeds, as compared to supersonic detonation.
Denver drill: A drill that essentially re-creates the rescue of Denver firefighter Mark Langvardt. It incorporates the use of a leveraged body and an inclined plane (bio-mechanics) to get a victim up and out of a narrow window in a narrow hallway (the Denver Prop).
Denver prop: A training prop designed after the actual dimensions of the confined area that claimed 16-year veteran fire fighter Mark Langvardt's life in 1992. Specifically, it is a 'hallway' 28" wide, 8' long with a window at one end that is 20" wide by 28" high and the sill is 42" from the floor. The prop is used for the Denver Drill.
Direct attack: A fire attack in which hoses are advanced inside a structure and hose streams are directed onto burning materials.
Discharge flow: The amount of water flowing from a fire hydrant when it is opened; compare to static flow and residual flow.
Determinate: (Response determinate) The level and type of response needed based on information provided by a caller reporting an incident. Often utilizing a structured questioning flow chart or algorithm.
Dispatch: Refers to person or place designated for handling a call for help by alerting the specific resources necessary.
Draft: The process of pumping water from a static source below the pump.
DOS: Death on scene. Also known as, "DOA" - Dead on arrival.
Drills: training during which an emergency is simulated and the trainees or personnel go through the steps of responding as if it were a real emergency.
Drop tank: A portable tank used at fire scenes to store water from Tenders for Engines
Dry riser: An empty pipe in a building which hoses can be connected to, so that water can be brought to the floor of a fire.

E

Electrical fire: A fire in which the primary source of heat is electricity, resulting in combustion of adjacent insulation and other materials; may be hazardous to attempt to extinguish using water.
EMR: Emergency medical responder.
EMS: Emergency medical service(s).
EMT: Emergency medical technician(s).
Engine: A fire suppression vehicle that has a water pump and, typically, carries hoses, other equipment and a limited supply of water.
Engineer: A firefighter responsible for driving the engine to the scene of the call and operation of the pumps on an engine, to provide sufficient water to the firefighters on the hose. The term may be either a position title or a rank; usage varies among departments.
Engine company: A group of firefighters assigned to an apparatus with a water pump and equipped with firehose and other tools related to fire extinguishment.
Engine house: [archaic] A firehouse housing an engine company.
Engine pressure: The pressure in a fire hose measured at the outlet of the pump.
Enhanced 9-1-1: Electronic system for automatic correlation of physical telephone lines with information about the location of the caller—a useful tool for dispatchers when the caller has an emergency but cannot speak.
Evacuation: Removal of personnel from a dangerous area, in particular, a HAZMAT incident, burning building, or other emergency. Also refers to act of removing firefighters from a structure in danger of collapsing.
Evolution: Uniform sequence of practiced steps by squad carrying out common tasks such as selection and placement of ladders, stowing hoses in hose bed, putting hoses and tools into service in particular patterns; intended to result in predictability during emergencies.
Exothermic reaction: Chemical reaction giving off heat in the process, such as combustion.
Explorer: a young adult, between 14 and 21, who learns the basics of firefighting.
Exposure: Property near fire that may become involved by transfer of heat or burning material from main fire, typically by convection or radiation. May range from to several miles, depending on size and type of fire or explosion.
Exterior attack: A method of extinguishing a fire which does not involve entering the structure. Often used when so much of the building is involved in fire that there is little or no benefit to risking firefighter safety by inserting them into the structure. May be a temporary measure when there are not sufficient personnel on scene to form an entry team and a rescue team (to rescue the entry team). Also known as surround and drown. Compare Interior attack.
Extrication: removal of a trapped victim such as a vehicle extrication, confined space rescue, or trench rescue; sometimes using hydraulic spreader, Jaws of Life, or other technical equipment.
ETOH: the chemical abbreviation for ethanol, or ethyl alcohol, also used to describe someone believed to be intoxicated.

F

FAST (or F.A.S.T.): Firefighter assist and search team (also called rapid entry team or rapid intervention team/crew)—firefighters assigned to stand by for rescue of other firefighters inside a structure; an implementation to support the two-in, two-out rule; may have specialized training, experience and tools. While all of these versions of the name for a firefighter rescue crew either have been used or continue to be used in several areas, the National Incident Management System (NIMS) has determined that rapid intervention crew ("RIC") will be the national term. Current U.S. federally mandated training programs are in the process of standardizing this and other terms under DHS and FEMA. F.A.S.T operations became officially mandated after the Worcester, MA Cold Storage fire, which claimed the lives of 6 firefighters, after they became disoriented in the smoke and subsequently ran out of air.
FDC (Fire department connection): Location in which pumping apparatus hooks to a buildings standpipe and or sprinkler system. Usually a 3″ female connection.
Fire barn: Another term for fire station. Originally it referred to a stable which housed horses and the fire apparatus which they hauled. Although it may be colloquially employed to describe any such structure, the term is now most commonly used in rural areas.
Firebreak: Especially in hilly or mountainous areas, roads or paths cut through brush with a tractor, bulldozer or other construction equipment. The purpose of these is to have an area with no brush, and thus, no fuel, so that a fire will hopefully burn out rather than jumping to another area with brush. Also to ensure vehicular access to brush areas.
Fire buff Someone with considerable interest (a fan) in fire fighting and emergency services, while not being an active member of these services.
Fire code (Fire safety code): regulations for fire prevention and safety involving flammables, explosives and other dangerous operations and occupancies.
Fire complex: (U.S. complex fire) Area of fires - many of the areas have multiple fires with multiple fronts.
Fire engineering: Scientific design of materials, structures and processes for fire safety
Fire escape: A building structure arranged outside to assist in safe evacuation of occupants during an emergency; may connect horizontally beyond a fire wall or vertically to a roof or (preferably) to the ground, perhaps with a counter-weighted span to deny access to intruders.
Fire Fighter Fatality Investigation and Prevention Program (FFFIPP)—Program administered by the National Institute for Occupational Safety and Health (NIOSH), a department of the Centers for Disease Control (CDC). It performs independent investigations of firefighter fatalities in the United States, also referred to as line of duty deaths (LODD). The programs goals are: 1.) to better define the characteristics of line of duty deaths among firefighters, 2.) to develop recommendations for the prevention of deaths and injuries, and 3.) to disseminate prevention strategies to the fire service.
Firefighter: People who respond to fire alarms and other emergencies for fire suppression, rescue, and related duties.
Firefighter assist and search team: See FAST.
Fire flow: The amount of water being pumped onto a fire, or required to extinguish a hypothetical fire. A critical calculation in light of the axiom that an ordinary fire will not be extinguished unless there is sufficient water to remove the heat of the fire.
Fire gas ignition: ‘an ignition of accumulated fire gases and combustion products, existing in, or transported into, a flammable state. There are a wide range of events that can be conveniently grouped under the heading Fire Gas Ignitions (FGI's) and such phenomena can generally be defined as -. Any such ignition is usually caused by the introduction of an ignition source into a pre-mixed state of flammable gases; or the transport of such gases towards a source of ignition; or the transport of a fuel-rich mixture of gases into an area containing oxygen and an ignition source. The ignition is not reliant on the action of airflow/oxygen in the direction of an ignition source, which is clearly recognised as a backdraft event.
Fireground: The operational area at the scene of a fire; area in which incident commander is in control. Also used as name of radio frequency to be used by units operating in the fireground, as in “Responding units switch to fireground.”
Fire hall Another term for fire station.
Fire hazard: Materials, structures or processes that may result in creating a fire, permitting a fire to grow undetected, or preventing people from escaping a fire.
Firehouse: Another term for fire station.
Fire hydraulics: The study of pumps, hoses, pipes, accessories and tools for moving water or other extinguishing agents from a water supply to a fire.
Fire inspector: A person responsible for issuing permits and enforcing the fire code, including any necessary premises inspection, as before allowing (or during) a large indoor gathering.
Fire line: A boundary of a fire scene established for public safety and to identify the area in which firefighters may be working.
Fire load (Btu/sq ft): An estimate of the amount of heat that will be given off during ordinary combustion of all the fuel in a given space; e.g., a bedroom or a lumberyard. More casually, the amount and type of contents in a given space.
Fire marshal: Administrative and investigative office for fire prevention and arson investigation.
Fire officer: A person tasked with organizing and directing firefighters. See also company officer and chief officer.
Fire point: temperature at which materials give off flammable gases that will sustain fire, typically higher than flash point. Temperature at flashover.
Fire police: Special constables attached to a fire department, tasked with ensuring the safety and security of emergency scenes as well as general assistance to the fire department and other agencies.
Fire prevention: Fire safety; standards for minimizing fire hazards. In some departments also the name of the division tasked with promoting fire safety and fire code compliance in the community.
Fire prevention week: An annual observation of fire safety education in the United States and Canada, often involving lectures or demonstrations by firefighters, sponsored by the National Fire Protection Association, since 1925.
Fire-resistant: Materials designed or treated to have an increased fire point.
Fire station: A structure which, in addition to housing apparatus and equipment, often includes living quarters and training facilities for the use of firefighting personnel when on-duty.
Firestorm: A conflagration of great enough proportions to noticeably create its own wind conditions.
Fire tetrahedron: The fire tetrahedron is based on the components of igniting or extinguishing a fire. Each component represents a property necessary to sustain fire: fuel, oxygen, heat, and chemical chain reaction. Extinguishment is based upon removing or hindering any one of these properties.
Fire triangle: An outdated model for understanding the major components necessary for fire: heat, fuel and oxygen. See also fire tetrahedron for the currently used model in firefighting.
Fire wall: Building structure designed to delay horizontal spread of a fire from one area of a building to another; often regulated by fire code and required to have self-closing doors, and fireproof construction.
Fire warden: Appointed post for issuing rural fire permits in a given jurisdiction and maintaining equipment and manpower readiness for responding to wildland fires.
Fire watch: Fixed or mobile patrols that watch for signs of fire or fire hazards so that any necessary alarm can be quickly raised or preventive steps taken. Commonly established at commercial, industrial and multi-occupancy structures, usually by building and property Maintenance or Security personnel if the on site fire alarm and/or sprinkler/suppression system is out of service for repairs, or a Fire crew assigned to the scene after a large fire to stand watch for an extended period of time in the event of a rekindle. Also called "reflash watch."
First due: Refers to either the first apparatus arriving on the scene of a fire or the area in which a company is expected to be the first to arrive on a fire scene.
Fit test: Periodic test of how well the facepiece of an SCBA fits a particular firefighter.
Flameover: Also known as rollover. The ignition of heated fire gasses at the ceiling level only. While dangerous to firefighters, this is not as deadly as Flashover.
Flammable range, limits: The percentage mixture of fumes with air that will sustain fire; outside the limits the mixture is either too lean or too rich to burn.
Flash point: Lowest temperature at which a material will emit vapor combustible in air mixture. Higher than Flame point of same material.
Flashover: simultaneous ignition of combustible materials in a closed space, as when materials simultaneously reach their fire point; may also result in rollover.
Foam: Extinguishing agent formed by mixing Foam concentrate with water and aerating the solution for expansion. Used for smothering large Class A or B fires. May be injected into fire streams at adjustable concentrations.
Foam concentrate: Raw foam liquid as it rests in it storage container before the introduction of water and air.
Forcible entry: gaining entry to an area using force to disable or bypass security devices, typically using force tools, sometimes using tools specialized for entry (e.g., Halligan, K-tool).
Forward lay: Procedure of stringing water supply hose from a water source toward a fire scene; compare with Reverse lay.
Freelancing: dangerous situation at an incident where an individual carries out tasks alone or without being assigned; violation of Personnel accountability procedures.
Friction loss: Reduction of flow in a firehose caused by friction between the water and the lining of the hose. Depends primarily upon diameter, type and length of hose, and amount of water (GPM) flowing through.
Frontage: The size of a building facing a street.
Fuel-controlled fire: Free burning of a fire that is characterised by an air supply in excess of that which is required for complete combustion of the fuel source or available pyrolates.
Fully involved: Term of size-up meaning fire, heat and smoke in a structure are so widespread that internal access must wait until fire streams can be applied.

G

Gas cooling or 3D water-fog: Branch technique where water spray in correct quantities can result in contraction of the gases without the over production of steam. May assist as a control measure in small compartment. This is not an extinguishing technique because it is still essential to apply water to the surfaces.
GPM: gallons per minute or how many gallons are being pumped out of a piece of equipment every minute.
GPM method ("gallons per minute"): Calculation of how much water, in GPM, will be necessary to extinguish a given volume of fire, under the circumstances (e.g., fuel class, containment, exposures, etc.).
Grease fire: A fire involving any manner of cooking oil or other flammable cooking or lubricating materials. Also known as an F (Europe, Australia) or K fire (America).
Goer: An incident with persons reported.
Grab: Rescuing a person from building.
Good access: the ability to access a patient or point of egress without assistance

H

Hand tub: A type of historical fire engine where a "tub" had to be filled by a bucket brigade and then pumped onto the fire by hand. An advancement from the hand tub was to a fire engine which was still pumped by hand but had a suction hose to supply water. Hand tubs were pulled to the fire by hand or some were designed to be pulled by horses.
Hand jack: To advance a line (hose) manually rather that deploy it from the hose bed of a moving piece of apparatus. Usually applies to supply lines. See Skulldrag
Hard line: A smaller hose about one inch in diameter used by firefighters to clean apparatus.
Hazard: a source of danger of personal injury or property damage; fire hazard refers to conditions that may result in fire or explosion, or may increase spread of an accidental fire, or prevent escape from fire. Under worker safety and health regulations, employers have a general duty to provide a workplace free of hazards. See also fire prevention, and HAZMAT.
HAZMAT: Hazardous materials, including solids, liquids, or gases that may cause injury, death, or damage if released or triggered.
Head pressure: How the pressure of a water stream is measured. By measuring the 'breakover' point, the point where the water stream breaks apart and begins to fall back to the ground, of a stream of water aimed vertically into the air. This is typically done with a hose and a fixed nozzle. Therefore, if a water stream breaks over at , then it is said the pump has of head pressure. Current measurements of pumping capacity are now in GPM, Gallons Per Minute.
Helitack: A rotary winged (helicopter) fire-fighting aircraft, such as the Erickson Skycrane which can be modified to hold 2100 gallons (9500L) of water or retardant.
High-pressure system: A supplemental pump system used to pressurize the water supply, sometimes used during a large fire, or whenever more than one hydrant is being used.
High-rise building: Any building taller than three or four stories, depending upon local usage, requiring firefighters to climb stairs or aerial ladders for access to upper floors.
High-rise pack: A shoulder load of hose with a nozzle and other tools necessary to connect the hose to a standpipe.
Hook ladder: Short ladder with a long hook at the top. The hook is used to smash a window and grip the window frame while the fire fighter climbs. Using one or two it is easy to go up and down floors beyond the reach of other ladders or when there's no space to pitch a ladder.
Horizontal standpipe: An operation involving laying a long length of large diameter hose from a pumper toward a fire structure, typically with a gated wye at the end that allows the connection of a couple of hand lines. This effectively moves the water supply closer to the fire, and greatly extends the reach of the hand lines when the apparatus cannot be placed any closer to the fire structure.
Hose pack: A hose pack is a backpack containing fire hose in a preconfigured arrangement, sometime completely made from fire hose without a bag.
Fire hose vacuum: A small pneumatic device that removes residue air from the inside of a fire hose, thereby making it smaller and somewhat rigid
Hotshot crew: An extensively trained group of approximately twenty people which specializes in wildfire suppression with little or no outside logistical support.
Hot-wash: A meeting, typically held after an incident is over, to discuss the successes and failures of the response and tactics used to be better prepared for the next incident.
Hot zone: contaminated area of HAZMAT incident that must be isolated; requires suitable protective equipment to enter and decontamination upon exit; minimum hot zone distance from unknown material with unknown release is 330 feet (United Nations Emergency Response Guidebook); surrounded by "warm zone" where decontamination takes place.

I

IAFF: Acronym, "International Association of Fire Fighters".
IAP: Acronym, "Incident Action Plan" A plan consisting of the strategic goals, tactical objectives, and support requirements for the incident. All incidents require an action plan. For simple incidents, the action plan is not usually in written form, while large/complex incidents require the action plan to be documented in writing. When complete, the IAP will have a number of attachments.
IDLH: Any situation deemed Immediately Dangerous to Life and Health. More narrowly defined by OSHA. See main IDLH article. An area of maximum danger to firefighters. Often requires increased Personnel accountability.
IFSTA: Acronym, "International Fire Service Training Association". A major publisher of firefighter training materials.
IMARP: Acronym, "Indiana Mutual Aid Response Plan". For the rapid activation and response of aid to a community in the event of a local disaster. These events can include a major fire, train derailments, hazardous materials incidents, wild land fires, domestic terrorism, and other events that may overwhelm the local fire department serving the community and its normal mutual aid resources.
Incident commander (or IC): The officer in charge of all activities at an incident. See Incident Command System.
Incident safety officer: The officer in charge of scene safety at an incident. See Incident Command System. Optional at any incident other than HAZMAT.
Incipient stage fire: A small fire that may be extinguished using portable fire extinguishers or other means typically at hand.
Indirect attack: Method of firefighting in which water is pumped onto materials above or near the fire so that the splash rains onto the fire, often used where a structure is unsafe to enter.
Initial attack: First point of attack on a fire where hose lines or fuel separation are used to prevent further extension of the fire.
Interface zone (also wildland/structural interface or urban/wildland interface): The zone where wildfires threaten structures or structural fires threaten wildlands, such as in residential areas adjacent to forests. This requires both wildland firefighting and structural firefighting in the same location, which involve very different tactics and equipment.
Interior attack: Inserting a team of firefighters into the burning structure, in an attempt to extinguish a blaze from inside the structure, minimizing property damage from fire, smoke, and water. Requires a minimum of four fully equipped firefighters: an entry team of at least two to enter the structure and fight the fire, and two standing by to rescue or relieve the entry team (see two in, two out). If the entry team(s) cannot extinguish the blaze, may become an Exterior Attack.
IMT: Acronym for incident management team. In the United States, there are predominantly five types of incident management teams (IMTs). An incident such as a wildland fire is initially managed by local fire departments or fire agencies, but if the fire becomes complex additional resources are called in to address the emergency, and higher levels of management training and capability are required. IMTs are "typed" according to the complexity of incidents they are capable of managing and are part of an incident command system.

:To manage the logistical, fiscal, planning, operational, safety and community issues related to the incident/emergency, an Incident Management Team will provide the command and control infrastructure that is required.

:Incident management starts as the smallest unit and escalates according to the complexity of the emergency. The five types of IMTs are as follows:

:*Type 5: Local village and township level – a "pool" of primarily fire officers from several neighboring departments trained to serve in Command and General Staff positions during the first 6–12 hours of a major or complex incident.

:*Type 4: City, county or fire district level – a designated team of fire, EMS, and possibly law enforcement officers from a larger and generally more populated area, typically within a single jurisdiction (city or county), activated when necessary to manage a major or complex incident during the first 6–12 hours and possibly transition to a Type 3 IMT.

:*Type 3: State or metropolitan area level – a standing team of trained personnel from different departments, organizations, agencies, and jurisdictions within a state or DHS Urban Area Security Initiative (UASI) region, activated to support incident management at incidents that extend beyond one operational period. Type 3 IMTs will respond throughout the state or large portions of the state, depending upon state-specific laws, policies, and regulations.

:*Type 2: National and state level – a federally or state-certified team; has less training, staffing and experience than Type 1 IMTs, and is typically used on smaller scale national or state incidents. There are 35 Type 2 IMTs currently in existence, and operate through interagency cooperation of federal, state and local land and emergency management agencies.

:*Type 1: National and state level – a federally or state-certified team; is the most robust IMT with the most training and experience. Sixteen Type 1 IMTs are now in existence, and operate through interagency cooperation of federal, state and local land and emergency management agencies.

:Although the primary purpose is for wildfire response, an Incident Management Team can respond to a wide range of emergencies, including fires, floods, earthquakes, hurricanes, tornadoes, tsunami, riots, spilling of hazardous materials, and other natural or human-caused incidents.

:The five subsystems of an incident management team are as follows:

:*Incident command system (ICS) an on-scene structure of management-level positions suitable for managing any incident.

:*Training development and delivery of training courses.

:*Qualifications and certification national standards for qualifications and certification for ICS positions.

:*Publications management development, control, sources, and distribution of NIIMS publications provided by the National Wildfire Coordinating Group (NWCG).

:*Supporting Technology and systems used to support an emergency response, such as Geographic Information Systems (GIS), orthophoto mapping, National Fire Danger Rating System, remote automatic weather stations, automatic lightning detection systems, infrared technology, and communications

ISO rating: (Insurance Services Office public protection classification rating) This is a rating published by the Insurance Services Office. Insurance companies, in many states, use this number to determine homeowner insurance premiums. Recently some insurance companies, including State Farm, have now adopted a per-zip-code, actual loss, based system in several states and no longer use the ISO (PPC) system.
Irons: The flathead axe mated with the halligan bar. Firefighters often refer to these as the crossed irons, or married irons, because the halligan bar can fit to the axe head.

J

Jumping-sheet: The sheet held by a group of firefighters onto which people caught in a burning building can jump. (obsolete)
Job: Northeast US Firefighter slang for structure fire
Junior firefighter: (US) a young adult between the ages of 14 and 18 that learns the basics of firefighting from firefighters usually in a volunteer fire company

==L==

Ladder company: A group of fire fighters, officers and engineers that staff a ladder truck.
Ladder slide (or ladder bail) A technique used to rapidly bail out of a window and onto a ladder face-first. After exiting the window, the firefighter quickly rotates 180 degrees to descend the ladder normally.
Layout: Establishing water supply. Usually done by first due engine company. Telling the next due in, to pick it up.
Lean: A fuel-air mixture that contains more air than fuel (unburned smoke). When the right ratio is present, backdraft or flashover can occur.
Level I, II, III Incident: A HAZMAT term denoting the severity of the incident and the type of response that may be necessary, where Level III is the largest or most dangerous. In some jurisdictions, level 0 is used for a small hazmat incident that can be handled by the responding fire department, but the incident commander wants either a phone or on scene consultation with someone from the hazmat team.
Life safety code: NFPA publication. Originally known as the "Building Exits Code."
Life line: A trademark for a wireless emergency call unit that triggers a telephone call to an emergency dispatcher when a button is pressed.
Line or hose line a line of hose, referred to by its size i.e. 1"3/4, 1 inch, 2 Inch, 5 inch
Line loss: See friction loss.
LODD (line of duty death) The death of a fire fighter while on-duty.
Live line: A fire hose under pressure from a pump. Also, an energized electrical line that may cause a hazard to firefighters.
Live in: A firefighter who typically lives in the fire house or station
Live training structure: A structure that is used for hands-on training. Can be custom built or acquired and modified for the purpose.
VEIS: Vent, enter, isolate, search - a further development of the VES concept, emphasizing the importance of isolating the room being searched from the rest of the building containing the seat of fire, by closing the door as soon as such door is found, in order to improve the tenability and visibility in the room.
Vertical ventilation: Ventilation technique making use of the principle of convection in which heated gases naturally rise. This is the classic cut-a-hole-in-the-roof method that helps release the smoke and hot gases that accumulate near the ceiling or attic space.
Voids (building): Enclosed portions of a building where fire can spread undetected.
Vollie: A volunteer firefighter.
Volunteer fire department: An organization of part-time firefighters who may or may not be paid for on-call time or firefighting duty time, but who in nearly all states are held to the same professional training standards and take the same examinations to advance in rank as career firefighters. [In some regions, particularly eastern New York, New Jersey, Pennsylvania and Maryland volunteer fire departments and fire protection districts have independent taxing authority and are equally as well equipped and paid while working as career fire department members.]

W

Watch: (UK) A group of firefighters who work at a station on same shift. Watches are often named with a colour, such as "Red Watch".
Water drop: A forest fire fighting technique when an airplane (also called an "airtanker") or helicopter drops a supply of water or other fire suppressant onto an exposed fire from above.
Water hammer: Large, damaging shock wave in a water supply system caused by shutting a valve quickly, or by permitting a vehicle to drive across an unprotected fire hose.
Well involved: Term of size-up meaning fire, heat and smoke in a structure are so widespread that internal access must wait until fire streams can be applied.
Wet down ceremony: A traditional ceremony for the placing of new apparatus in service. There are several versions of this but it usually includes: pushing the old apparatus out, wetting down the new vehicle and pushing it back into the station. It may also include the moving of the bell to the new apparatus, photos, etc.
Wet riser: A pipe in a building filled with water, which hoses can be connected to, so that water can be brought to the floor of a fire.
Wildfire or wildland fire: Fire in forests, grasslands, prairies, or other natural areas, not involving structure fires (although wildland fires may threaten structures or vice versa - see interface zone.) For a complete list of terms used in wildland fire, see Glossary of wildland fire terms.
Wholetime firefighter: (U.K. and Ireland) A firefighter who is employed full-time.
Working fire: A fire that is in the process of being suppressed. Typically reserved for a structure fire or an outside fire with a considerable fire load that requires the incident command system be initiated, additional support and suppression assets dispatched, and necessary notifications made to other municipal agencies. Otherwise known as a "real" fire that will probably not be handled quickly by a single company.
Woo-woo: A firefighter (typically, but not always a volunteer firefighter) who regularly flaunts the fact they are a firefighter to the people around them.

Z

Zone: Section of structure indicated on a fire alarm control panel where sensor was activated, which may also have separate HVAC and fire suppression controls. May also refer to the act of zoning a geographic area in which certain types of occupancies are restricted or preferred, due to concerns for fire safety and the availability of fire protection and emergency evacuation routes.

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References