NWCG Glossary of Wildland Fire, PMS 205

This glossary provides the wildland fire community a single source for wildland fire and incident management terminology commonly used by the NWCG and its subgroups.

Glossary entries related to Organizations, IT Applications, and NWCG Positions have been removed from the glossary based on term inclusion criteria. For more information about the glossary and the criteria, see the About the NWCG Glossary page or the NWCG User Guide for the Glossary of Wildland Fire, PMS 937.

Reference Definitions

Some of the terms within this glossary will be followed by initials or will have references or comments at the end of the definition to help broaden the recognition and understanding of the term. An explanation of those references is as follows:

Also called: Means there is another term that may sometimes be in use, but is not defined in this glossary.
Acronym: An abbreviation formed from the initial letters of other words and pronounced as a word. An acronym appears in parentheses following the term.
Initialism: An abbreviation consisting of initial letters pronounced separately. An initialism appears in parentheses following the term.
See: Means there is another, preferred term that should be used instead. In such a case only the preferred term is defined in this glossary.
See Also: Means there are one or more related terms that may also be of interest to the glossary user. The related terms are also defined in this glossary.
Synonym: Means the term is synonymous with another. The terms have the same, or essentially the same, definition and the terms are interchangeable in their use.
Definition Extension: An example, further explanation, or usage guidance in support of the definition.

Glossary Acronyms/Initialisms

6 (1) | A (126) | B (94) | C (160) | D (102) | E (67) | F (261) | G (48) | H (90) | I (83) | J (10) | K (4) | L (74) | M (92) | N (31) | O (47) | P (133) | Q (6) | R (100) | S (221) | T (71) | U (28) | V (37) | W (60) | Z (1)
  • A circular-like flow of a fluid (such as air or water) drawing its energy from a flow of much larger scale, and brought about by pressure irregularities as in the downwind (lee) side of a solid obstacle. For example, wind conditions may be erratic and may eddy on the downwind side of large rock outcroppings, buildings, etc. 
  1. The place where plant communities meet or where successional stages or vegetative conditions within plant communities come together.
  2. The boundary between two fairly distinct fuel types. 
Edge Firing
  • Method of burning in which fires are set along the edges of an area and allowed to spread inward. 
  • A device used to introduce and mix fire chemical into a water stream. An eductor is a fitting with three ports, an inlet for water flow, an outlet for water flow, and an inlet for fire chemical concentrate. The flow of water through the eductor produces a region of lower pressure at the fire chemical inlet, drawing the chemical into the water stream. 
Effective Windspeed
  • The midflame wind speed adjusted for the effect of slope on fire spread. 
  • A siphon device used to fill an engine's tank when the water source is below or beyond the engine's drafting capability. 
  • Conceptually represents the optimum integration of modern educational methods and professional staff development training with state of the art technology. The primary goal is enhancing on-the-job performance, motivation, and learning performance. 
Elevation Loss
  • In hydraulics, the pressure loss caused by raising water through hose or pipe to a higher elevation (roughly equal to one psi for every two-foot increase in elevation above the pump) (11.3 kPa per meter). 
  • Any incident which requires the response of a fire protection organization's attack units and/or support units. 
Emergency Equipment Rental Agreement (EERA)
  • An agreement written at an incident using an EERA, OF-294. The duration is for the length of the incident only.
Emergency Firefighter (EFF)
  • A person employed as an emergency worker on a forest or wildland fire which threatens damage to property under public management. Emergency firefighters are hired for the duration of the emergency only. 
Emergency Locator Transmitter (ELT)
  • A radio transmitter attached to the aircraft structure which operates from its own power source on 121.5 MHz and 243 MHz. The transmitter transmits a distinctive downward swept audio tone for homing purposes and is designed to function without human action after an accident. 
Emergency Operations Plan
  • The plan that each jurisdiction has and maintains for responding to appropriate hazards. 
Emergency Response Provider
  • Any federal, state, or local emergency public safety, law enforcement, emergency responder, emergency medical (including hospital emergency facilities), and related personnel, agencies, and authorities. It is any organization responding to an emergency, or providing mutual aid support to such an organization, whether in the field, at the scene of an incident, or operations center. 
Emergency Stabilization
  • Planned actions to stabilize and prevent unacceptable degradation to natural and cultural resource, to minimize threats to life or property resulting from the effects of a fire, or to repair/replace/construct physical improvements necessary to prevent degradation of land or resources. 
Emergency Support Function (ESF)
  • Groupings of governmental and certain private sector capabilities and functions into an organizational structure to provide support, resources, program implementation, and services that are most likely needed to support disaster response operations.
  • A release of combustion gases and aerosols into the atmosphere. 
Emission Factor (EFp)
  • The mass of particulate matter produced per unit mass of fuel consumed (pounds per ton, grams per kilogram). 
Emission Rate
  • The amount, or mass of smoke produced per unit of time. For example: Emission Rate = Available Fuel x Burning Rate x Emission Factor. 
Emission Reduction
  • A strategy for controlling smoke from prescribed fires that minimizes the amount of smoke output per unit area treated. 
Emission Standard
  • A general type of standard that limits the mass of a pollutant that may be emitted by a source. The most straightforward emissions standard is a simple limitation on mass of pollutant per unit time (e.g., pounds of pollutant per hour). 
Empty Weight
  • Weight of an aircraft/engine including the structure, power plant, all fixed equipment, all fixed ballast, unusable fuel, undrainable oil, and total quantity of hydraulic fluid. 
Energy Release Component (ERC)
  • The computed total heat release per unit area (British thermal units per square foot) within the flaming front at the head of a moving fire. 
  • Any ground vehicle providing specified levels of pumping, water, and hose capacity but with less than the specified level of personnel. 
Engine Company
  • A resource that includes an engine of a specific type. The type specifies tank capacity, pump rating, hose capacity and number of personnel. 
  • A situation where personnel are unexpectedly caught in a fire behavior-related, life-threatening position where planned escape routes or safety zones are absent, inadequate, or compromised. An entrapment may or may not include deployment of a fire shelter for its intended purpose. These situations may or may not result in injury. They include "near misses."
Entrapment Avoidance
  • A process used to improve the safety of personnel on the fireline, which emphasizes tools and tactics available to prevent being trapped in a burnover situation. This process includes appropriate decision making through risk management, application of LCES, use of pre-established trigger points, and recognition of suitable escape routes and safety zones. 
  • Direct attack with multiple anchor points, that allows for multiple points of attack. Generally used as an engine tactic in the wildland urban interface. 
  • The complex surroundings of an item or area of interest, such as air, water, natural resources, and their physical conditions (temperature, humidity). 
Environmental Lapse Rate
  • The actual rate of decrease of temperature with elevation. 
Episode (Pollution)
  • A condition of poor contaminant dispersion which may result in concentrations considered potentially harmful to health or welfare. Episodes may also occur during periods of fairly good dispersion if the source of air contaminants is extremely large. 
Equilibrium Moisture Content (EMC)
  • Moisture content that a fuel particle will attain if exposed for an infinite period in an environment of specified constant temperature and humidity. When a fuel particle reaches equilibrium moisture content, net exchange of moisture between it and its environment is zero. 
Equipment Use Fire
  • Fire caused by mechanical equipment other than railroad operations. 
Escape Route
  • A preplanned and understood route firefighters take to move to a safety zone or other low-risk area. When escape routes deviate from a defined physical path, they should be clearly marked (flagged). 
Escaped Fire
  • Fire which has exceeded or is expected to exceed initial attack capabilities or prescription. 
ESF Coordinator
  • An entity which oversees the preparedness activities for a particular ESF and coordinates with its primary and support agencies.
ESF Primary Agency
  • A Federal agency with significant authorities, roles, resources, and capabilities for a particular function within an ESF.
ESF Support Agency
  • An entity with specific capabilities or resources that support the primary agencies in executing the mission of the ESF.
Estimated Position Error (EPE)
Estimated Time En Route (ETE)
  • Term used in resource planning/following to estimate time spent between points. 
Estimated Time of Arrival (ETA)
  • Term used in resource planning/following to estimate time of arrival at a point. 
Estimated Time of Departure (ETD)
  • Term used in resource planning/following to estimate time of departure from a point. 
  • An organized, phased, and supervised withdrawal, dispersal, or removal of civilians from dangerous or potentially dangerous areas, and their reception and care in safe areas. 
  • To review and compare outcomes with management and incident objectives desired for a wildland fire. One of the six component activities in an adaptive management process that may lead to adjusting future actions. 
  • The individual who is qualified in the position being evaluated, or supervises the position being evaluated, having responsibility for observing task(s) being performed and documenting successful performance for agency certification or re-certification. Evaluator responsibilities must remain separate from the individual assigned as Trainer/Coach. 
  • The transformation of a liquid to its gaseous state; heat is released by the liquid during this process. 
  • A planned, non-emergency activity. ICS can be used as the management system for a wide range of events, e.g., parades, concerts or sporting events. 
Evidence Protection Area
Exempt / Nonexempt
  • Categories of employees as defined in the Fair Labor Standards Act (FLSA), who are either covered or exempted from coverage under the ActPay entitlements vary depending on the employee's FLSA status. 
Exhaust Primer
  • Device which uses the exhaust gas flow of an engine for priming a centrifugal pump. 
Expanded Dispatch
  • An organization needed to support an incident which expands along with the Incident Command System. 
  • The ratio of the volume of the foam in its aerated state to the original volume of the non-aerated foam solution. 
Expert Witness
  • Someone with sufficient skill, knowledge, or experience in a given field so as to be capable of drawing inferences or reaching conclusions or opinions that an average person would not be competent to reach. The expert's opinion testimony should aim the judge or jury in their understanding of the fact at issue. 
Exposed Side
  1. Property that may be endangered by a fire burning in another structure or by a wildfire.
  2. Direction in which a slope faces, usually with respect to cardinal directions.
  3. The general surroundings of a site with special reference to its openness to winds. 
Exposure Fire
  • Classification for a fire not originating in a building, but which ignites building(s). A fire originating in one building and spreading to another is classified under the original cause of fire. 
  • To drop retardant in such a way that the load slightly overlaps and links a previous drop. "Extend your last drop."
Extended Attack
Extended Attack Incident
  • An incident that exceeds the capability of the initial attack resources and/or organization to successfully manage the incident to conclusion. 
Exterior Fire Protection
  • The protection of structures from the exterior, with no interior access or activity. 
External Load
  • A load that is carried or extends outside of the aircraft fuselage. 
External Payload
  • Maximum external stress load (in pounds) with full fuel and pilot in calm air at standard atmospheric temperature. 
Extinguishing Agent
  • Substance used to put out a fire by cooling the burning material, blocking the supply of oxygen, or chemically inhibiting combustion. 
Extra Burning Period
  • For any particular fire which is neither contained nor controlled, any 24-hour period following the termination of the first burning period. 
Extreme Fire Behavior
  • Extreme implies a level of fire behavior characteristics that ordinarily precludes methods of direct control action. One or more of the following is usually involved: high rate of spread, prolific crowning and/or spotting, presence of fire whirls, strong convection column. Predictability is difficult because such fires often exercise some degree of influence on their environment and behave erratically, sometimes dangerously. 
  • Person who sees evidence of criminal activity, actual commission of a crime or a criminal fleeing a crime scene.