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)
  • Cards filled out with essential information for each resource they represent. The cards are color-coded to represent different types of resources. 
Tactical Decision Game (TDGS)
  • A simple role-play simulation technique that challenges participants to make decisions and communicate those decisions to others. A tactical decision game is an experiential learning method that is tactical in nature and has time and information constraints to put participants under some level of stress.
Tactical Direction
  • Direction given by the operations section chief which includes the tactics appropriate for the selected strategy, the selection and assignment of resources, tactics implementation, and performance monitoring for each operational period. 
  • Deploying and directing resources on an incident to accomplish the objectives designated by strategy. 
  • Connecting a (airtanker) drop to the forward part of a previous drop. 
Tail Rotor
  • A small rotor, mounted on the tail of a conventional helicopter, which counteracts torque of the main rotor and provides a measure of directional control. 
Tailgate Safety Session
  • Brief meetings held at the beginning, during, or end of an operational period to discuss new work assignments, new work methods, changes in plans, use of tools and equipment, and recognition and protection against work hazards that may be encountered. 
  • Two or more units of any one type working one in front of the other to accomplish a specific fire suppression job; the term can be used in connection with crews of firefighters, power pumps, bulldozers, etc. 
Tank and Gating System
  • Tanks, doors, and release mechanism installed in aircraft for cascading fire retardants. 
Tank Trailer
  • Specialized trailer on which is mounted a tank, fire pump, hose, and ancillary equipment. 
  • Specific portion of the fire on which fire retardant or water is to be dropped by airtankers or helitankers.
Target Hazard
  • Facilities in which there is great likelihood of loss of life or property. 
  • A unit of work activity that is a logical and necessary action in the performance of a behavior; how the behavior is demonstrated or performed in a particular context. 
Task Force
  • Any combination of single resources assembled for a particular tactical need, with common communications and a leader. A task force may be pre-established and sent to an incident, or formed at an incident. 
Temperature Coefficient
  • The relative change of some measurable quantity with change of temperature, like burning time per unit length, mostly expressed as mean change per degree in percentage of mean temperature within a certain range. 
Ten-hour Timelag Fuel Moisture (10-h TL FM)
  • The moisture content of the l0-hour timelag roundwood fuels. 
Ten-hour Timelag Fuels
  • Dead fuels consisting of roundwood 1/4 to l-inch (0.6 to 2.5 cm) in diameter and, very roughly, the layer of litter extending from immediately below the surface to 3/4 inch (1.9 cm) below the surface. 
Terra Torch ®
  • Device for throwing a stream of flaming liquid, used to facilitate rapid ignition during burn out operations on a wild fire or during a prescribed fire operation. 
Test Fire
  • A prescribed fire set to evaluate such things as fire behavior, fire effects, detection performance, or control measures. 
Thermal Belt
  • An area of mountainous slope (characteristically the middle third), where the top of the radiation inversion intersects the slope. It typically experiences the least variation in diurnal temperatures and has the highest average temperatures and, thus, the lowest relative humidity. Its presence is most evident during clear weather with light wind. 
Thermal Imagery
  • The display or printout of an infrared scanner operating over a fire. Also known as infrared imagery. 
Thin Layer
  • Layer of clouds whose ratio of dense sky cover to total sky cover is 1/2 or less. 
Thin Sky Cover
  • Sky cover through which higher clouds or the sky can be detected. 
Third-Party Case
  • An injury or illness/disease caused by a person or object under circumstances that indicate there may be a legal liability on a party other than the federal or state government. Contact the home unit for case management advice.
  • An incident likely to cause damage or danger to protected lands.
    • Business Rule:  Responding organization determines threat to protected lands.
Threat Fire
  • Any uncontrolled fire near to or heading toward an area under organized fire protection. 
  • Localized storm characterized by one or more electrical discharge(s). 
  • Act of connecting a control line to another fireline or an intended firebreak. 
Time Delay Device
  • A device employed to allow a firesetter the opportunity to leave the scene prior to the ignition of the fire. 
Time in Service
  • With respect to maintenance time records, the time from the moment an aircraft leaves the surface of the earth until it touches at the next point of landing. 
Time Recording
  • Recording all time presented by others. Personnel time recorders record time from the Crew Time Report, SF-261, to the Incident Time Report, OF-288. Equipment time recorders record time from the Emergency Equipment Shift Ticket, OF-297, to the Emergency Equipment Use Invoice, OF-286.
Time Unit
  • Functional unit within the Finance/Administration Section responsible for recording personnel time and managing the commissary. 
Time-Temperature Curve
  • Graph showing the increase in temperature at a specified point in a fire as a function of time, beginning with ignition and ending with burnout. 
  • Tracking on-shift time of incident resources. Timekeeping is accomplished on the Crew Time Report, SF-261, or the Emergency Equipment Shift Ticket, OF-297.
Timelag (TL)
  • Time needed under specified conditions for a fuel particle to lose about 63 percent of the difference between its initial moisture content and its equilibrium moisture content. If conditions remain unchanged, a fuel will reach 95 percent of its equilibrium moisture content after 4 timelag periods. 
  • Burnable organic material (duff, peat, rotten wood, etc.) with a high surface to volume ratio. 
  • Nozzle tips used to change orifice size of a hose stream. 
  1. Ignition and subsequent envelopment in flames, usually from bottom to top, of a tree or small group of trees.
  2. To set fire to property deliberately and maliciously.
  3. A professional firesetter-for-hire. 
  • The burning of the foliage of a single tree or a small group of trees, from the bottom up. 
Total Fuel
  • All plant material both living and dead that can burn in a worst case situation. 
Total Mobility
  • The capability to move, position, and utilize established forces to meet existing and anticipated fire protection needs nationwide. 
Total Risk
  • Part of the National Fire Danger Rating System (NFDRS). Sum of lightning and human-caused risk values; cannot exceed a value of 100. 
Total Suspended Particulate Matter (TSP)
  • Particles emitted from a pollution source regardless of size. Federal and state ambient and emission standards exist for TSP. 
Touchdown Pad
  • That portion of a heliport or helispot where the helicopter lands. 
  • The hours of a day (a daily tour-of-duty) and the days of an administrative workweek (a weekly tour-of-duty) that constitutes an employee's regularly scheduled administrative workweek.
  • Relating to a harmful effect by a poisonous substance on the human body by physical contact, ingestion, or inhalation. 
Toxic Substance
  • A chemical or mixture that may present an unreasonable risk of injury to health or the environment. 
  • A rubber tired or tracked rider-controlled automotive vehicle, used in wildland fire management for pulling a disk or a plow to construct fireline by exposing mineral soil. 
Tractor Plow
  • A steel tracked vehicle with or without a front mounted blade equipped with a plow for exposing mineral soil. Sometimes a tractor plow with a front mounted blade is referred to as a dozer plow.
Traffic Pattern
  • Traffic flow that is prescribed for aircraft landing at, taxiing on, and taking off from, an airport. Usual components of a traffic pattern are upwind leg, crosswind leg, downwind leg, base leg, and final approach. 
Trail Drop
  • An unbroken line of retardant used for constructing a retardant line. 
  • Combustible material, such as rolled rag, blankets and newspapers, or flammable liquid, used to spread fire from one area to others; usually used in conjunction with an incendiary device. 
  • An individual who has met all required training and position experience for a specified position and is approved by their home unit's certifying official, to initiate a performance based training assignment in order to become qualified in the position. 
  • A position-qualified individual who provides instruction to a trainee in the classroom, on-the-job, or on an incident. While many of the requirements of the trainer/coach are similar to the evaluator, it is important that the roles of training and evaluation remain separate. 
Transfer of Command
  • The ICS management process in which the on-scene incident commander at a specified time hands off command responsibilities to the incident commander that will be taking over incident command. 
  • In the 1978 version of NFDRS, the herbaceous stage when herbaceous fuel moisture is between 120% and 30%. 
Transition Zone
  • Area of change between advancing, lateral, and backing vectors.
Translational Lift
  • Lift that is gained when a helicopter translates from a hover into forward flight; additional lift increases with increasing airspeed and is derived by the rotor system moving into undisturbed air. 
Transport Wind Speed
  • A measure of the average rate of the horizontal transport of air within the Mixing Layer. May also be the wind speed at the final height of plume rise. Generally refers to the rate at which emissions will be transported from one area to another. 
Transportation Map
  • Base map of the planning unit showing all roads, trails, heliports, and airfields existing and programmed for construction. 
Travel Time
  • Compensable time en route to or from an emergency incident. 
  • A small ditch often constructed below a fire on sloping ground (undercut or underslung line) to catch rolling material. 
  • An elongated area of relatively low atmospheric pressure, usually extending from the center of a low pressure system. 
True Airspeed
  • Velocity of an aircraft in its flight path relative to the air through which it is moving. 
True Bearing
  • Bearing by true north rather than magnetic north. 
  • Irregular motion of the atmosphere usually produced when air flows over a comparatively uneven surface such as the surface of the earth; or when two currents of air flow past or over each other in different directions or at different speeds. 
Turn the Corner
  • Contain a fire along a flank of the fire and begin containing it across the head. Refers to ground or air attack. 
Turnaround Time
  • Time used by an airtanker or helitanker to reload and return to the fire. 
Turnout Coat
  • A coat with a fire resistant outer shell and a thermal and moisture barrier liner. Used primarily by structure firefighters. Also known as a fire coat. 
Two-Way Radio
  • Radio equipment with transmitters in mobile units on the same frequency as the base station, permitting conversation in two directions using the same frequency in turn. 
  • Refers to resource capability. A Type 1 resource provides a greater overall capability due to power, size, capacity, etc., than would be found in a Type 2 resource. Resource typing provides managers with additional information in selecting the best resource for the task.