unified action
urgent priority
A category of immediate mission request that is lower than emergency priority but takes precedence over ordinary priority; e.g., enemy artillery or mortar fire that is falling on friendly troops and causing casualties or enemy troops or mechanized units moving up in such force as to threaten a breakthrough. See also immediate mission request; priority of immediate mission requests.
terminal control
threshold
The beginning of that portion of the runway usable for landing.
triple point
The intersection of the incident, reflected, and fused (or Mach) shock fronts accompanying an air burst. The height of the triple point above the surface, i.e., the height of the Mach stem, increases with increasing distance from a given explosion.
true horizon
1. The boundary of a horizontal plane passing through a point of vision. 2. In photogrammetry, the boundary of a horizontal plane passing through the perspective center of a lens system.
safe haven
1. Designated area(s) to which noncombatants of the United States Government's responsibility and commercial vehicles and materiel may be evacuated during a domestic or other valid emergency. 2. Temporary storage provided to Department of Energy classified shipment transporters at Department of Defense facilities in order to assure safety and security of nuclear material and/or nonnuclear classified material. Also includes parking for commercial vehicles containing Class A or Class B explosives. 3. A protected body of water or the well deck of an amphibious ship used by small craft operating offshore for refuge from storms or heavy seas.
shock front
The boundary between the pressure disturbance created by an explosion (in air, water, or earth) and the ambient atmosphere, water, or earth.
standing order
A promulgated order which remains in force until amended or cancelled.
static line (air transport)
A line attached to a parachute pack and to a strop or anchor cable in an aircraft so that, when the load is dropped, the parachute is deployed automatically.