DA - Danger Area.
DAAIS - Danger Area Activity InＦＯＲＭation Service.
DACS - Danger Area Crossing Service.
DADC - Digital air data computer (DADS - /system).
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.
dB - decibel(s) - a unit of sound
DC - direct current
DCT - direct
dead side - opposite side of an airfield circuit pattern from which aircraft join for landing
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\
DETRESFA - distress phase of search-and-rescue operation.
DF - direction-finding. A DF bearing can be provided by airfields or other facilities such as D & D cells (above) having suitable direction-finding equipment to locate an aircraft.
DG - Directional gyro
DGAC - Direction Général à l\
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.
DHFS - UK Defence Helicopter Flying School at RAF Shawbury
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.
downwind - The segment of an aerodrome circuit paralleling the active runway and flown on a reciprocal heading
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 \fuel.
DZ - dropping zone, for parachuting etc. E
EAA - Experimental Aircraft Association, the American homebuilders\
EADI - electronic attitude director indicator. An ADI with CRT cockpit display ＦＯＲＭing part of an EFIS, below.
EAS - equivalent airspeed.
EAT - estimated (or expected) approach time.
EBAA - European Business Aircraft Association.
ECAC - European Civil Aviation Conference.
ECOGAS - European Council of General Aviation Support.
ECU - environmental control unit.
ED - emergency distance.
EET - estimated elapsed time.
EFAS - electronic flash approach light system.
EFATO - engine failure at (or after) take-off.
EFIS - electronic flight instrument system, in which multi- function CRT displays replace traditional instruments for providing flight, navigation and aircraft systems inＦＯＲＭation, ＦＯＲＭing a so-called \and helicopters, military fighters and some GA piston singles and twins.
EGT - exhaust gas temperature (gauge). A device which provides a cockpit readout of the exhaust gas temperature of an aircraft\for maximum fuel efficiency.
EHSI - electronic horizontal situation indicator. CRT-based HSI ＦＯＲＭing part of an EFIS.
EICAS - engine indication and crew alerting system. CRT display which monitors engine perＦＯＲＭance and alerts the crew to system or airframe failure. Found in new-generation transports and business jets.
EICMS - engine in-flight monitoring system
ELT - emergency locator transmitter. A small radio transmitter fixed to an aircraft\which is automatically activated by impact or water immersion and transmits a code on emergency frequencies enabling SAR satellites or search units equipped with DF to locate the crash or ditching site. Carriage mandatory in the USA, but not in UK. Sometimes styled ADELT, automatically deployable ELT, or ELB, emergency locator beacon.
empty weight - weight of the basic aeroplane including all fixed equipment, plus unusable fuel, oil, hydraulic and other fluids.
encoding altimeter - an altimeter which gives a digital output to the transponder (which see)
for automatic transmission of the aircraft\
EOBT - estimated off-blocks time.
EP - Elementary pilot rating of the British Hang Gliding and Paragliding Association
EPNdB - effective perceived noise decibel. Unit of measurement of aircraft noise levels.
ER - extended range.
eshp - equivalent shaft horsepower.
ETA - estimated time of arrival. Also ;
ETD - estimated time of departure
ETE - estimated time en route.
ETOPS - extended-range twin operations, usually long over-water flights by airliners.
ETPS - Empire Test Pilots School, based at the Aircraft & Armament Experimental Establishment, Boscombe Down.
Eurocontrol - organisation, headquartered in The Netherlands, comprising Belgium, France, Germany, Ireland, Luxembourg, Netherlands and UK for coordinating en route air traffic control in Europe.
F
FAA - Federal Aviation Administration, USA, equivalent of UK\
FAA - Fleet Air Arm, of UK\
FADEC - full-authority digital engine control.
FAF - final approach fix, the point at which a published instrument approach begins.
FAI - Fédération Aéronautique Internationale, the international body for verification of aeronautical record attempts and sporting regulations.
FAR - Federal Aviation Regulations (USA).
FARA - ＦＯＲＭula Air Racing Association.
FBL - fly by light i.e. control via optical fibres
FBO - fixed-base operator, American term for commercial operators supplying fuel, maintenance, aircraft sales, rental, flight training, handling and other GA services at an airport. (So-called because the first FBOs were early barnstormers who chose to settle at one field.)
FBW - fly-by-wire. Aircraft control systems in which pilots\control surfaces electronically or via fibre optics rather than by mechanical linkage. Also see FBL.
FCL - Flight Crew Licensing (Division), a CAA department handling all aspects of private and professional pilot, flight engineer and navigator licensing.
FCS - flight control system.
fcst - forecast.
FDR - flight data recorder, popularly known as a \by which various parameters of an aircraft\ＦＯＲＭance are recorded for analysis in the event of an incident or accident.
feather - (of a propeller) - to set the angle of CS or VP propeller edge-on to the airflow to minimise drag and rotation following engine failure on multi-engined aircraft. Also applies to motor gliders which have feathering propellers to enhance engine-off soaring perＦＯＲＭance.
final(s) - final approach. The part of a landing sequence or aerodrome circuit procedure in which the aircraft has made its final turn and is inbound to the active runway. Downwind is the segment of the circuit paralleling the runway and flown on a reciprocal heading. Base leg is the crosswind segment bringing the aircraft from the downwind leg to final approach. The leg before downwind is called the Crosswind leg.
FIC - Flight InＦＯＲＭation Centre.
FIR - Flight InＦＯＲＭation Region. UK airspace is divided into two FIRs, London and Scottish.
FIS - Flight InＦＯＲＭation Service, providing a variety of services and inＦＯＲＭation (but not control) to air traffic in the two FIRs above.
FJ - fast jet.
FL - flight level, a level of constant atmospheric pressure shown by an altimeter set to a standard 1013.2 millibars, expressed in rounds hundreds of feet, thus FL330 is 33,000 feet.
flag - warning signal incorporated in certain navigation and flight instruments indicating that the instrument is not operating satisfactorily or that the strength of signals being received from
