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NWCG Glossary of Wildland Fire (PMS 205)

Term Steward Status Definition
triangulation
trough IWSC Incident Weather Subcommittee Approved An elongated area of relatively low atmospheric pressure, usually extending from the center of a low pressure system.
truck trail IOSC Incident Operations Subcommittee Archived Substantial transportation route for fire suppression motor vehicles, built prior to a fire. Also known as a fire road.
true airspeed AMC Aviation Management Committee Approved Velocity of an aircraft in its flight path relative to the air through which it is moving.
true bearing IOSC Incident Operations Subcommittee Approved Bearing by true north rather than magnetic north.
true north
turbulence IWSC Incident Weather Subcommittee Approved 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 IOSC Incident Operations Subcommittee Approved Contain a fire along a flank of the fire and begin containing it across the head. Refers to ground or air attack.
turnaround time SEATB Single Engine Airtanker Board, IAB Interagency Airtanker Board Approved Time used by an airtanker or helitanker to reload and return to the fire.
turnout coat ETSC Equipment/Technology Subcommittee Approved A coat with a fire resistant outer shell and a thermal and moisture barrier liner. Used primarily by structure firefighters.
twist MFES Mobile Fire Equipment Subcommittee Approved The twisting of a hose when hydrostatic pressure is applied. The twisting is either left or right as observed in the direction of flow.
two-way radio IMC Integration Management Committee, DCSC Dispatch Coordination Subcommittee Approved 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.
tympanic membrane EMSC Emergency Medical Subcommittee Approved A thin membrane separating the middle ear from the inner part of the external auditory canal that vibrates in response to sound energy and transmits the resulting mechanical vibrations to the structures of the middle ear—called also eardrum, tympanum.
type QMC Qualifications Management Committee, NISC NIMS Integration Subcommittee Approved A NIMS resource classification that refers to capability of a specific kind of resource to which a metric is applied to designate it as a specific numbered class.
Ultra High Frequency (UHF-FM) IMC Integration Management Committee, DCSC Dispatch Coordination Subcommittee Approved Radio frequencies from 300 Megahertz (MHz) to 3,000 MHz with a normal range of less than 50 miles. Radio frequency common to military aircraft and used in the logistics radio system. The most common frequencies used by fire and public safety are from 406 MHz to 512 MHz. 
unacceptable risk SRC Safety/Risk Management Committee Approved Level of risk as determined by the risk management process which cannot be mitigated to an acceptable safe level.
unauthorized passenger AMC Aviation Management Committee Approved All personnel who are not official or unofficial passengers are considered unauthorized passengers and are not authorized to be transported in any aircraft owned or operated by or on behalf of the government.
unavailable Pending The resource is not available to fill a resource order request.
unavailable (transferred) DCSC Dispatch Coordination Subcommittee Pending The resource has been transferred to another dispatch, but the transfer has not been completed.
uncontrolled airport AMC Aviation Management Committee Approved Airport not having an approved agency with radio communications to direct aircraft take-offs and landings.
uncontrolled fire IOSC Incident Operations Subcommittee Approved Any fire which threatens to destroy life, property, or natural resources, and (a) is not burning within the confines of firebreaks, or (b) is burning with such intensity that it could not be readily extinguished with ordinary tools commonly available.
underburn FMSC Fuels Management Subcommittee Approved A fire that consume surface fuels but not the overstory canopy.
undercut line IOSC Incident Operations Subcommittee Approved A fireline below a fire on a slope. Should be trenched to catch rolling material.
understory burning FMSC Fuels Management Subcommittee Approved Prescribed burning under a forest canopy.
unified area command wfnwcgorg:ICSC Approved A unified area command is established when incidents under an area command are multijurisdictional.
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