Commonly Used Fire Department Terms

Pulled from: East Glenville Fire Department & Carmel Fire Department


  • 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 into and making themselves announced as being on-scene during an incident to an incident commander or accountability officer. Through the accountability system, each person is tracked throughout the incident until released from the scene by the incident commander or accountability officer. 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).
  • Aerial operation: Means master streams flowing from elevated locations, generally the tips of aerial ladders or platforms during defensive operations.
  • Alarm: (1) System for detecting and reporting unusual conditions, such as smoke, fire, flood, loss of air, HAZMAT release, etc.; (2) Centralized dispatch center for interpreting alarms and dispatching resources. See fire alarm control panel.
  • All clear: Means that a primary search has been conducted and nothing was found.
  • 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.
  • Alpha, Bravo, Charlie, Delta: These terms are used to designate the sides of a structure. Generally speaking, the “alpha” side is the front of the structure, the “bravo” side is the left side of the structure, “Charlie” is the back of the structure and “delta” is the right side of the structure.
  • Ammonium nitrate: Component of ANFO; contents of two ships that exploded in Texas City Disaster, killing over 500 people, including all 28 volunteer firefighters at the scene.
  • ANFO: Ammonium Nitrate Fuel Oil combination making a high explosive.
  • Apparatus: A term usually used by firefighters describing a department vehicle (i.e. fire engine).
  • Arson: The crime of maliciously (or perhaps recklessly) setting fire to property, especially a dwelling. Punishable in various degrees, depending upon the circumstances.
  • Assuming command: Means that the first arriving unit has assumed responsibility for the incident and will be directing the activities of all other units until relieved by a Chief Officer. It will also be announced when a later arriving Chief Officer takes over for the first arriving officer and assumes command responsibilities.
  • 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 extended 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).
  • 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. IC must assess available flow to determine whether additional apparatus or streams are required. See Fire flow requirement.


  • 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: A tactic 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.
  • 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. Back me up – is a message fire officers regularly send to a later arriving fire crew. It is an assignment that means deploy a 1 3/4″ hand line and come in behind me to provide protection as we engage in firefighting activities.
  • 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.
  • Basic life support: Noninvasive emergency life-saving care to treat airway obstruction, cardiac arrest or respiratory arrest.
  • Battalion Chief: The lowest ranking Chief officer. These chiefs are often in charge of running calls and supervising multiple stations or districts within a city. A Battalion Chief is usually the officer in charge of a single-alarm working fire.
  • Blitzfire (or ground monitor): Is a ground mounted master stream device.
  • 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 propane tank). If the contents are flammable, the rapidly released vapor may react in a secondary fuel-air explosion.
  • Bunker coat, bunker pants: The protective coat and trousers worn by a firefighter for interior structural firefighting. Also called turnout coat and turnout pants.
  • Bus: Common term (firefighter slang) usually referring to an Ambulance


  • CAD: Computer Aided Dispatch System that is used by Public Safety Communications Officers in the Emergency Command Center. This automated system verifies address information recommends units to respond based upon the “closest resource concept,” time-stamps all activities tied to the incident (report time, response time, on-scene time and other timekeeping functions).
  • CAFS: A CAFS unit is an Engine that has a special foam system called a “Compressed Air Foam System.” This system mixes foam, water and air to create an extinguishing agent that is more effective than water and much lighter. The light weight makes it easier for firefighters to move hand lines thereby reducing fatigue.
  • Carbon Monoxide: A colorless, odorless toxic flammable gas formed by incomplete combustion of carbon.
  • Chimney fire: Fast and intense fire in a chimney flue in which accumulated creosote and other combustion byproducts ignite.
  • Class A fire: A fire involving combustibles such as wood, paper, and other natural materials.
  • Class B fire: A fire involving hydrocarbons.
  • Class C fire: An electrical fire.
  • Class D fire: A fire involving metals, such as sodium, titanium, magnesium, potassium, uranium, lithium, plutonium and calcium.
  • Cockloft: Structural space above ceiling and below rafters, often connecting adjacent occupancies and permitting fire to spread laterally, often unseen.
  • Collapse zone: A relatively poor place to park the engine near a burning structure. Estimated as an area one and a half times the height of the fire building.
  • Command: Refers to the individual in charge of the incident that is directing the activities of all other responders.
  • Company: Two or more firefighters arranged as a team.
  • Confined space: A confined space is any space: 1) that has limited or restricted means of entry or exit; 2) is large enough for a person to enter to perform tasks; 3) and is not designed or configured for continuous occupancy.
  • Crash Tender: A pump capable of spraying foam used at airports.
  • 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.


  • Dalmatian: “Firehouse dog.”
  • Dead lay: A load of hose on a pumper, but not connected to a pump outlet. Often used for larger supply lines.
  • Deflagration: An explosion with a propagation front traveling at subsonic speeds, as compared to supersonic detonation.
  • Defensive: Means that conditions are too dangerous to allow firefighters to operate inside of the structure.
  • Direct attack: “Putting the wet stuff on the red stuff.” A form of fire attack in which hoses are advanced to the fire inside a structure and hose streams directed at the burning materials.
  • Discharge flow: The amount of water flowing from a fire hydrant when it is opened; compare to static flow and residual flow.
  • Dispatch: Refers to person or place designated for handling a call for help by alerting the specific resources necessary. Division (Sector) – is a geographical area where firefighting activities are taking place. For example, firefighting operations taking place in the front of the building may be designated as the Alpha Division. Operations in the rear may be designated as the Charlie Division. All personnel working in a Division are under the direct supervision of a Division Supervisor.
  • Dozer: A vital piece of firefighting equipment; a dozer, operated by a Heavy Fire Equipment Operator, is used on wildland fires to cu fire breaks and construct a line around the fire. Dozers are also used to prepare fire prone areas but constructing firebreaks.
  • Draft: The process of pumping water from a source below the pump.
  • Drills: Training during which an emergency is simulated and the trainees go through the steps of responding as if it were a real emergency.


  • 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.
  • EMS: Emergency Medical Service.
  • EMT: A specially trained medical technician certified to provide basic emergency services (as cardiopulmonary resuscitation) before and during transportation to a hospital – called also emergency medical technician.
  • Engine: Is a fire truck that carries and pumps water.
  • Engine house: Early form of firehouse when pumper was the only dedicated fire apparatus.
  • 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.
  • 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 40 feet to several miles, depending on size and type of fire or explosion.
  • Extension: Means the fire has extended into concealed spaces within the building. “Checking for extension” means that firefighters are opening up concealed spaces to see if the fire has extended to other parts of the building.
  • 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.


  • FAST (or F.A.S.T.): Firefighter Assist and Search Team (also called Rapid Entry Team or Rapid Intervention Team) – 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.
  • Fast attack mode: Means that the first arriving officer, based on conditions encountered, has determined that it will be necessary for him/her to participate in the fire attack instead of taking a stationary Command position.
  • Fire code (Fire safety code): Regulations for fire prevention and safety involving flammables, explosives and other dangerous operations and occupancies.
  • 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.
  • Firefighter: People who respond to fire alarms and other emergencies for fire suppression, rescue, and related duties. Formerly called “firemen”, but modern term includes women as well.
  • Fire flow: The amount of water being pumped onto a fire. A critical calculation in light of the axiom that an ordinary fire will not go out unless there is enough heat being removed by enough water.
  • 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 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. Where fire apparatus is stored and where full-time firefighters work.
  • 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.
  • Fire Marshal: Administrative and investigative office for fire prevention and arson investigation.
  • Fire point: Temperature at which materials give off flammable gases that will sustain fire, typically higher than flash point. Temperature at flashover.
  • Fire prevention: Fire safety; standards for minimizing fire hazards.
  • Fire-resistant: Materials designed or treated to have an increased fire point.
  • 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: Model for understanding the major components necessary for fire – heat, fuel and oxygen. See also fire tetrahedron for a more comprehensive model.
  • 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 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.
  • Fit test: Periodic test of how well the face piece of an SCBA fits a particular firefighter.
  • 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. Lower than fire 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.
  • 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.
  • 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.


  • Geographic Information System (GIS): Captures, stores and analyzes geography-based information for tactical incident management.
  • 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.
  • Group: Refers to a one or more fire companies responsible for a specific function. For example, a group responsible for ventilating the structure would be called a ventilation group.


  • Handline: Is a firefighting hose that is operated and maneuvered by firefighters (usually a 1 3/4″ in diameter).
  • 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 gasses that may cause injury, death, or damage if released or triggered.
  • 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.
  • 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.


  • IDLH: Any situation deemed Immediately Dangerous to Life and Health. More narrowly defined by OSHA. An area of maximum danger to firefighters.
  • Incident Commander: The officer in charge of all activities at an incident. See Incident Command System.
  • Incident Management System: A management structure that can be quickly adapted to any situation, a standard approach with predefined roles, responsibilities, procedures and terminology.
  • Incident Safety Officer: The officer in charge of scene safety at an incident. See Incident Command System.
  • 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.
  • ISO Rating: (Insurance Services Office Fire Insurance Rating) This is a rating published by the Insurance Services Office. Insurance companies use this number to determine homeowner insurance premiums.


  • Jack-knifing: Jargon for position of articulated aerial ladder such that tractor is at an angle to the trailer; provides improved stability when ladder is hoisted, rotated and extended.


  • Knocked down: Means the main body of the fire has been suppressed.


  • Ladder: A fire truck that has an extension ladder, carries certain firefighting equipment and can be set up to flow large quantities of water from an elevated position is called a “Ladder Truck.” When communicating over the radio, a reference such as “Ladder 35” is referring to the crew of Ladder Truck 35.
  • Ladder Company: A group of fire fighters, officers and engineers that staff a ladder truck.
  • Laying an inch and three quarter line: Means that an fire company has pulled a 1 3/4″ hose (handline) and will be engaged in fire suppression activities.
  • Laying our preconnect: Means that an fire company has pulled a 1 3/4″ hose (handline) and will be engaged in fire suppression activities.
  • 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.
  • Life safety code: NFPA publication.
  • 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 loss: See friction loss.
  • Live line: A fire hose under pressure from a pump. Also, an energized electrical line that may cause a hazard to firefighters.
  • Loaded stream: A hose stream that has had a surfactant added to assist in penetrating burning materials.


  • Marginal: Means that conditions are severe and pose a significant risk to firefighters entering the structure. The only justification for entering the building when operating under the marginal mode is to check for and remove endangered occupants.
  • Mass casualty: Any incident that produces a large number of injured persons requiring emergency medical treatment and transportation to a medical facility. The exact number of patients that makes an incident “mass casualty” is defined by departmental procedures and may vary from area to area.
  • Master box: An alarm system in which a local fire-alarm system triggers a fire alarm box (the master box) to signal the fire condition to a central monitor.
  • Master stream: A large nozzle, either portable or fixed to a pumper, capable of throwing large amounts of water relatively long distances.
  • Mayday: Is any emergency transmission that means a firefighter is in trouble and is in need of rescue.
  • Means of egress: The way out of a building during an emergency; may be by door, window, hallway, or exterior fire escape; local fire codes will often dictate the size, location and type according to the number of occupants and the type of occupancy.
  • Mobile Command: means that the command is not operating at a fixed location.
  • Mop-up: Extinguishing or removing burning material near control lines, felling snags, and trenching logs to prevent rolling after an area has burned, to make a fire safe, or to reduce residual smoke.
  • Multiple alarms: A request by an incident commander for additional personnel and apparatus. Each department will vary on the number of apparatus and personnel on each additional alarm.
  • Mutual aid: An agreement between nearby fire companies to assist each other during emergencies by responding with available manpower and apparatus.


  • NFPA: The National Fire Protection Association, which sets a number of standards for firefighting, equipment, and fire protection in the United States, and also adopted in many other countries.
  • NIOSH: National Institute for Occupational Safety and Health. A U.S. agency responsible for investigation of workplace deaths, including firefighters.
  • Nozzle pressure: Pressure in a fire hose measured at the nozzle.
  • Nozzle reach: The distance a fire stream will travel from the nozzle tip before breaking up or evaporating due to air friction or heat.
  • Nozzle reaction: The force felt when water is pumped through a nozzle, e.g., 350 US gallons per minute (22 L/s) would produce a force of 40 pounds force (180 N) against the firefighter holding the nozzle.


  • Occupancy: Zoning and safety code term used to determine how a structure is permitted to be used and occupied, which in turn dictates the necessary safety structures and procedures.
  • Occupancy class: General categories of structures for purpose of safety planning, such as for hospital, assembly, industrial, single-family dwelling, apartment building, commercial, etc. Further broken down by types of hazards associated with particular occupancies, such as gas stations.
  • Occupant Services: The term Occupant Services is used to describe the coordinated process of managing the needs of displaced occupants. Firefighters assigned Occupant Services duties attend to the provision of food, shelter, clothing, and other such post disaster needs.
  • Occupant-use hose: Light-weight firehose coupled to standpipe for emergency use by building occupants prior to arrival of firefighters. Often accessible by breaking glass to unlock secure enclosure.
  • Offensive attack: Method of firefighting in which water or other extinguisher is taken directly to the seat ofthe fire, as opposed to being pumped in that general direction from a safe distance.
  • On-call: Personnel who can be summoned (and paid) when necessary to respond to an incident; a type of “volunteer” fire department.
  • On-Scene: Means that a unit has arrived at the scene of an emergency.
  • OSHA: U.S. government agency concerned with regulating employee safety, particularly in hazardous occupations such as firefighting.
  • Overhauling: Late stage in fire-suppression process during which the burned area is carefully examined for remaining sources of heat that may re-kindle the fire. Often coincides with salvage operations to prevent further loss to structure or its contents, as well as fire-cause determination and preservation of evidence.
  • Oxidizer: A hazardous material containing oxygen that can combine with adjacent fuel to start or feed a fire.


  • Paramedic: A person trained to give emergency medical care to people who are seriously ill with the aim of stabilizing them before they are taken to the hospital.
  • Personal alert safety system: A device worn by a firefighter that sounds an alarm if the firefighter is motionless for a period of time.
  • Personnel accountability report: End-result of personnel accountability system. Best report is “All hands, AOK” – worst is “squad missing”.
  • Personnel accountability system: Tag, ‘passport’, or other system for identification and tracking of personnel at an incident, especially those entering and leaving an IDLH area; intended to permit rapid determination of who may be at risk or lost during sudden changes at the scene.
  • Platform: Is a fire truck that has an extension ladder with a working platform at the end, carries certain firefighting equipment and can be set up to flow large quantities of water from elevated positions.
  • Positive pressure: Pressure at higher than atmospheric; used in SCBA face pieces and in smoke-proof stairwells to reduce entry of smoke or fumes through small openings.
  • Personal Protective Equipment (PPE): The helmet, hood, coat, gloves, self-contained breathing apparatus and boots worn by firefighters to protect against heat and water.
  • Preconnect: Refers to a 1 3/4″ preconnected hoseline that is our basic firefighting line. A common radio transmission is, “We’re laying our preconnect.” which means there is an active fire and firefighting operations are in progress.
  • Pre-fire, pre-incident planning: Information collected by fire prevention officers to assist in identifying hazards and the equipment, supplies, personnel, skills, and procedures needed to deal with a potential incident.
  • Pre-planning: Fire protection strategy involving visits to potentially hazardous occupancies for inspection, follow-up analysis and recommendations for actions to be taken in case of specific incidents.
  • Primary search: Is a rapid search of unburned portions of the fire building for trapped occupants.
  • “Probie”: (also rookie) New firefighter on employment probation (a period of time during which his or her skills are improved, honed, tested, and evaluated).
  • Public alarm: Means for public to report a fire, includes telephone, street-corner pull-boxes, building pull-stations, and manual bells or sirens in rural areas.
  • Pump operator, technician: (also a chauffeur): Person responsible for operating the pumps on a pumper and typically for driving the pumper to an incident.
  • Pumper Company: Squad or company that mans a fire engine (pumper) and carries out duties involving getting water to the fire.
  • Pyrolysis: Process of converting a solid substance to combustible fumes by raising its temperature. See also vaporization of liquids.


  • Quint: A fire truck that has an aerial ladder as well as a pump, hose, tank and ladders.


  • Radiant extension: Fire that has transferred ignition heat to adjacent materials across open space. One reason some city fire codes prohibit windows facing each other in adjacent warehouses.
  • Recovery: Location and removal of deceased victims. Also, the time needed for a firefighter to spend in rehab before being considered ready to continue working the incident.
  • Redline: Is a small diameter handline (usually 1″ in diameter and used for small fires).
  • Residential sprinkler system: A sprinkler system arranged for fire suppression in a dwelling.
  • Residual pressure: The amount of pressure in a hydrant system when a hydrant is fully open, such as during a fire; should be engineered to provide domestic supply of water to homes and businesses during a large fire in the district.
  • Responding: Means a unit is enroute to the emergency scene.
  • Return to quarters: Means that the fire unit is not needed at the incident and may return to the fire station.
  • Reverse lay: The process of stringing hose from a fire toward a source of water, i.e., a fire hydrant
  • Run card system: A system of pre-planning for fire protection in which information about specific detectors, hazards, or other emergency response plans is indexed by location, for rapid reference during an alarm.


  • Salvage, salvage cover: Heavy-duty tarpaulins folded or rolled for quick deployment to cover personal property subjected to possible water or other damage during firefighting.
  • Scuttle hatch: Ready-made opening in roof that can be opened for vertical ventilation.
  • Search and rescue (or SAR): Entering a fire building or collapse zone for an orderly search for victims and removal of live victims. Becomes “recovery” if victims are not likely to be found alive.
  • Sector: A physical or operational division of an incident; An area supervised as a branch in the Incident Command System. A typical system for structure fires names the “front” of the building “sector A”, and continues clockwise around the building (B, C, D), with interior sectors denoted by the floor number (1, 2, 3, etc.). A “rehab” sector is one example of an operational division at an incident, where personnel are assigned after strenuous work in another sector.
  • Secondary Search: Is a slow methodical search after the fire is out. The purpose of the secondary search is to determine if there was a fire victim that may not have been found during the primary search.
  • Self-contained Breathing Apparatus (SCBA): Respirator with independent air supply used by firefighters to enter toxic and otherwise dangerous atmospheres.
  • Shelter-In-Place: is to seek safety within the building one already occupies that is a small, interior room, with no or few windows, and taking refuge there.
  • Shoulder load: The amount of hose a single firefighter can pull off a hose wagon or pumper truck and carry toward the fire.
  • Size-up: Initial evaluation of an incident, in particular a determination of immediate hazards to responders, other lives and property, and what additional resources may be needed. Example – “Two-story brick taxpayer with heavy smoke showing from rear wooden porches and children reported trapped.”
  • Smoke explosion: See backdraft. Smoke-proof stairwell: Building structure which isolates escape stairwells with relatively fireproof walls, self-closing doors, and positive pressure ventilation, to prevent smoke or fumes from entering the stairwell during evacuation of occupants during a fire or other emergency.
  • Solid stream: Fire stream from round orifice of nozzle. Compare straight stream.
  • Staging: Sector of incident command where responding resources arrive for assignment to another sector. Often an essential element in personnel accountability program.
  • Staging Area: An area where on-scene resources can assemble while awaiting an assignment.
  • Standard operating procedure, guideline: Rules for the operation of a fire department, such as how to respond to various types of emergencies, training requirements, use of protective equipment, radio procedures; often include local interpretations of regulations and standards.
  • Static pressure: The pressure in a water system when the water is not flowing.
  • Straight lay: Means that an Engine company is deploying a supply line and is laying the line from the hydrant to the fire.
  • Straight stream: Round, hollow stream formed as water passes a round baffle through a round orifice (e.g., on an adjustable nozzle.) Compare solid stream.
  • Stretch: Command to lay out (and connect) firehose and nozzle.
  • Structural fire: Fire involving houses, buildings, or other structures. Urban fire departments are primarily geared toward structural firefighting. The terms structural fire and structural firefighting are often used to distinguish them from wildland fire.
  • Supply Line: Is a large diameter fire hose that is used to move water from a fire hydrant to a fire apparatus.


  • Tailboard: Portion at rear of fire engine where firefighters could stand and ride (now considered overly dangerous), or step up to access hoses in the hose bed.
  • Taxpayer: Description of a fire building used primarily as a private dwelling.
  • Thermal Imaging Device: An electronic device that detects differences in temperature based on infrared energy and then generates images based on that data. Commonly used in obscured environments to locate victims.
  • Truck Company: Apparatus that carries ladders, forcible entry tools, possibly extrication tools and salvage covers; firefighters who typically carry out tasks with such tools, including roof ventilation; also called “Ladder Company”.
  • Two-in, two-out (or “two in/two out”: Refers to the standard safety tactic of having one team of two firefighters enter a hazardous zone (IDLH), while at least two others stand by outside in case the first two need rescue – thus requiring a minimum of four firefighters on scene prior to starting interior attack. Also refers to the “buddy system” in which firefighters never enter or leave a burning structure alone.
  • Type I, II, III, IV, V Building: U.S. classification system for fire resistance of building construction types, including definitions for “resistive” Type I, “non-combustible” Type II, “ordinary” Type III, heavy timber Type IV, and “frame construction” Type V (i.e., made entirely of wood).


  • Under control: Means that the fire is no longer a threat to the building and the operation is transitioning from fire control to overhaul operations.
  • Universal precautions: The use of safety barriers (gloves, mask, goggles) to limit an emergency responder’s contact with contaminants, especially fluids of injured patients.
  • Urban Search and Rescue Team: Highly-trained emergency responders who carry out specialized rescue operations that can respond globally in a structured rotation. Other parts of these teams include canines, specialized cameras, infrared equipment and other resources.


  • Vapor suppression: Process of reducing the amount of flammable or other hazardous vapors, from a flammable liquid, mixing with air, typically by careful application of a foam blanket on top of a pool of material.
  • Ventilation: Important procedure in firefighting in which the hot smoke and gases are removed from inside a structure, either by natural convection or forced, and either through existing openings or new ones provided by firefighters at appropriate locations (e.g., on the roof). Proper ventilation can save lives and improper ventilation can cause backdraft or other hazards.
  • Vertical ventilation: Ventilation technique making use of the principle of convection in which heated gases naturally rise. Voids (building) – Enclosed portions of a building where fire can spread undetected.
  • Vollie: A volunteer firefighter.
  • Volunteer fire department: A group of part-time firefighters who may be unpaid or paid when on-call, during incidents, or drills. Often professionally trained and equipped with state-of-the-art equipment.


  • Water drop: A forest fire fighting technique when an aircraft drops a supply of water 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.
  • Water Tender: A fixed-tank mobile vehicle that supplies fire engines with water when other water sources are not available. Some water tenders have the capability of “side-bar” pumping, or pumping directly from the tank while mobile. Tanks on water tenders range in size from 500 gallons to over 5,000 gallons.
  • 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.)
  • Working fire: A fire that is in the process of being suppressed; often a cue for dispatch of additional resources.



  • Yield: What other drivers are supposed to do when they see or hear emergency vehicles approaching with lights and/or sirens activated.


  • Zone: Section of structure indicated on fire alarm control panel where sensor was activated.