Terms Flashcards
Civil Twilight
Evening Civil Twilight is the period that begins at sunset and ends in the
evening when the center of the sun’s disk is 6 degrees below the horizon. Morning Civil Twilight
begins prior to sunrise when the center of the sun’s disk is 6 degrees below the horizon
Critical Phase of Flight
terminal area operations including taxi, takeoff and landing, low-level flight, air refueling,
airdrop, weapons employment, flight using NVDs, tactical/air combat and formation operations
Mountainous Terrain
In other areas, use 500 ft. surface elevation change over a ½ NM.
OROCA
off-route altitude which provides obstruction clearance with a 1,000 ft. buffer in
non-mountainous terrain areas and a 2,000 ft. buffer in designated mountainous areas within the
United States. This altitude may not provide signal coverage from ground-based navigational
aids, air traffic control radar, or communications coverage.
ORTCA
off-route altitude that provides terrain clearance with a 3,000 ft. buffer from
terrain. This altitude may not provide signal coverage from ground-based navigational aids, air
traffic control radar, or communications coverage. This altitude is used on en route charts
covering those areas outside the United States.
Prevailing Visibility
The greatest horizontal visibility observed throughout at least half
of the horizon circle. It need not be continuous throughout 180 consecutive degrees.
PRM Approach
An instrument landing system (ILS) approach conducted to parallel runways
whose extended centerlines are separated by less than 4,300 ft. and the parallel runways have a
PRM system that permits simultaneous independent ILS approaches
Reduced Vertical Separation Minimum (RVSM)
Reduces the vertical separation between
properly equipped and certified aircraft to 1000 ft. in special qualification airspace, normally
between FL290-410 inclusive.
Runway Environment
the threshold,
threshold markings or threshold lights, the runway end identifier lights, the touchdown zonelights, the runway or runway markings, the runway lights, the visual approach slope indicator.
Standard Formation
A formation in which no participating aircraft is more than 1 NM
horizontally and 100 ft. vertically from the lead aircraft.
Terminal Area Operations
Terminal area operations are normally those flight phases
conducted within 30 NM of an airfield
Unmonitored Navigational Aid
Most NAVAIDs have internal monitoring systems that
provide automatic shutdown or notification when a malfunction occurs. Unmonitored NAVAIDs
lack the ability to immediately notify ATC when a malfunction occurs
