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D & D - Distress & Diversion Cells at Air Traffic Control
Centres. RAF units which provide a 24 hour listening watch on VHF and
UHF emergency frequencies and can locate and assist pilots who are
lost or in emergency situations.
DA - Danger Area. Also DACS Danger Area Crossing Service. Also
DAAIS Danger Area Activity Information Service.
DADC - Digital air data computer (DADS /system).
dB - decibel(s) a unit of sound
DC - direct current
DCT - direct
deadstick - descent and landing with engine(s) shut down and
propeller(s) stopped.
Decca - hyperbolic area navigation system, originally
developed for maritime use, based on signals received from a chain of
master and slave ground stations located in northern Europe.
DEEC - digital electronic engine control
density altitude - pressure altitude corrected for air
temperature.
derated - engine's potential power deliberately limited,
lengthening likely life.
DETRESFA - distress phase of search and rescue operation.
DF - direction indicator. A gyro instrument which indicates the
magnetic heading of an aircraft. The DI, also known as the directional
gyro (DG), is free of the turning errors associated with magnetic
compasses but is prone to precession (wander) and must be finding
equipment to locate an aircraft.
DH - decision height. The height on a precision approach at
which a pilot must have the runway approach lights in sight to
continue the descent, or if not, must initiate a go around.
DI - direction indicator. A gyro instrument which indicates the
magnetic heading of an aircraft. The DI, also known as the directional
gyro (DG), is free of the turning errors associated with magnetic
compasses but is prone to precession (wander) and must be reset
against the magnetic compass at intervals. ALSO
DI - is also used to refer to the daily inspection a thorough
pre-flight check of an aircraft prior to the first flight of the day.
dihedral - sloping up from root to tip. Opposite: anhedral.
DIN(S) - digital interial navigation (system).
DME - distance measuring equipment. A combination of ground and
airborne equipment which gives a continuous slant range distance from
station readout by measuring time lapse of a signal transmitted by the
aircraft to the station and responded back. DMEs can also provide
groundspeed and time to station readouts by differentiation.
Doppler - Doppler effect (or shift) is the change in frequency
of light, radio or sound waves when source and receiver are in
relative motion.
DoT - Department of Transport.
DP - dew point
DR - dead (deduced) reckoning. Plotting position by calculating
the effect of speed, course, time and wind against last known
position.
dry - when referring to aircraft hire charges means 'without
fuel', as opposed to wet, with fuel.
DZ - dropping zone, for parachuting etc. |
