D to F

D

DAACM	Direct Airfield Attack Combined Munition (CBU-98/B)
DAB	Defense Acquisition Board (US)
DACT	dissimilar air combat training
DADC	digital air data computer
DADS	digital air data system
DAFCS	digital automatic flight control system
DARPA	Defense Advanced Research Projects Agency (US DoD, was ARPA)
DASA	Deutsche Aerospace AGAG (now EADS DASA)
DASS	Defensive Aids SubSystem
databus	electronic network for passing digital data between aircraft sensors and system processors
dB	Decibel
DBNS	Doppler bombing/navigation system
DBS	Doppler beam sharpening
DC	direct current
DDI	digital display indicator
dead-stick landing	landing of powered aircraft with all engines stopped
DECU	digital engine control unit
DEMVAL	DEMonstration & eVALuation (US)
derated	engine restricted to a power less than its maximum potential
DERA	Defence Evaluation and Research Agency (UK, subsequenty became QinetiQ)
DESO	Defence Export Services Organisation (UK-MoD)
DEW	Distant Early Warning (US)
DF	Direction Finding
DFCS	digital fire control system
DFDR	digital flight data recorder
DFVLR	Deutsche Forschungs-und Versuchsanstalt für Luft-und Raunmfahrt(German aviation research establishment)
DGAC	Direction Générale de l'Aviation Civile (France's airworthiness authority)
diamond landing gear	configuration with tandem mainwheels on centreline and outriggers on wing
DIANE	Digital Integrated Attack Navigation Equipment
dibber bomb	one which penetrates a concrete runway before exploding
dihedral	upward slope of wing from root to tip
DINAS	digital inertial navigation/attack system
DINS	digital inertial navigation system
dipole aerial	one composed of two conductors in line, fed at the mid-point, with a total length equal to one half wavelength
dirty	used to describe configuration of aircraft with undercarriage, flaps, air brakes etc extended
disc loading	helicopter weight divided by main rotor disc area
disposable load	total weight of payload, usable fuel, crew and any other masses which can be loaded and unloaded
DLC	direct lift control
DME	distance-measuring equipment (beacon-based navaid) Doppler radar employing frequency shift due to relative target motion in order to measure ground-speed or detect moving objects
DMZ	demilitarised zone
DO	design/drafting/drawing office
DoD	Department of Defense (US)
dog-tooth	step in wing leading edge where chord increases (similarly saw-tooth)
Doppler	radar based on the fact that received frequency is a function of relative velocity between transmitter or reflecting surface and receiver
DOSAAF	Dobrovol'noe Obshchestvo Sodeistviya Armii, Aviatsii i Flotu (Voluntary Association for support of the [former Soviet] Army, Aviation and Fleet), the now defunct paramilitary sport flying organisation which undertook all Soviet basic military flying training
double-slotted flap	flap with additional aerofoil ahead of main flap to increase maximum lift
DR	(1) dead reckoning or (2) dispatch reliability
DRA	Defence Research Agency (UK), now absorbed by DERA
dry lease	lease of commercial aircraft from one airline to another without flight/cabin crew or supporting services
DSFC	direct side-force control
duty runway	runway designated to be in use for flying operations at a specific time
DVI	direct voice input
DWS	Dispenser Weapon System (MBB)
DZ	dropping-zone

E

EAA	Experimental Aircraft Association (US)
EAP	Experimental Aircraft Programme (UK)
EAS	equivalent airspeed (rectified airspeed, with a compressibility correction)
EC	(1) electronic combat or (2) Escadre de Chasse (French fighter wing)
ECCD	electronic cockpit control device
ECCM	electronic counter-countermeasures
ECM	electronic countermeasures
ECR	Electronic Combat and Reconnaissance (Tornado variant)
ECS	Electronic Combat Squadron (USAF)
ECS	environmental control system
ECU	(1) electronic control unit or (2) environmental control unit or (3) engine change unit
EDU	(1) electronic display unit or (2) engine diagnostic unit
EEZ	Economic Exclusion (or Exclusive-Economic) Zone
EFA	European Fighter Aircraft (later Eurofighter 2000, now Eurofighter Typhoon)
EFCS	electronic flight control system
EFIS	electronic flight instrumentation system
EFM	Enhanced Fighter Manoeuvrability
EFS	Enhanced Flight Screener (USAF)
EGT	exhaust gas temperature (or JPT)
EHF	extremely high frequency
ehp	equivalent horsepower - propulsive power of a turboprop engine arrived at by adding the shp and the residual thrust from the jet
EICAS	engine indication and crew alerting system
EIS	electronic instrument system
EL	emitter locator
elevator	moveable surface for controlling aircraft in pitch
elevon	control surface on wing trailing edge which combines elevator and aileron functions
ELF	extremely low frequency
ELINT	ELectronic INTelligence
ELS	emitter location system
ELT	emergency locator transmitter
EM	electro-magnetic
EMC	electro-magnetic compatibility
EMD	engineering and manufacturing development
EMDG	Euromissile Dynamics Group
EMP	electro-magnetic pulse (eg, from nuclear explosion)
ENAER	Empresa Nacional de Aeronautica (Chile)
envelope	outer covering of balloon or airship which encloses the gas or hot-air
EO	electro-optical
EOB	electronic order of battle
EPR	engine pressure ratio
EPU	emergency power unit
ER	extended range
EROPS	Extended-Range OPerationS
ESM	electronic support measures (for the identification, location and recording of enemy emitters)
ESSS	external stores support system
ETA	estimated time of arrival
ETD	estimated time of departure
ETE	estimated time en route
ETOPS	Extended-range Twin-engine OperationS (capability of aircraft to fly a route always within two or three hours flying time from a usable alternative airfield)
ETPS	Empire Test Pilots School (Boscombe Down)
EUCLID	EUropean Co-operation for the Long-term In Defence
EW(O)	electronic warfare (officer)
EW	early warning
EWSM	early warning support measures
externally blown flap	one over the upper surface of which engine bleed air is blown to prevent airflow separation

F

FAA	(1) Federal Aviation Administration (US) or (2) Fleet Air Arm (UK)
FAC	forward air control(ler)
FADEC	full-authority digital engine (or electronic) control
FAE	fuel-air explosive
FAI	Féderation Aeronautique Internationale
FANS	Future Air Navigation System
FAR	Federal Aviation Regulations - Pt 23 refers to the airworthiness of private and air taxi aircraft with a maximum weight of no more than 5,670kg (12,500lb), and Pt 25 refers to public transport aircraft exceeding this figure
FARP	forward area rearm/refuel point or forward arming and refuelling point
FBL	fly-by-light
FBW	fly-by-wire (electrically-signalled flying controls)
FCR	fire control radar
FCS	flying/flight control system
FDO	flight deck officer
FDR	flight data recorder
feathering	aligning pitch of propeller blades with slipstream to minimise drag and prevent windmilling when engine is shut down
FEBA	forward edge of the battle area
fence	chordwise wing surface projection, often extending around leading edge, intended to prevent spanwise flow
fenestron	form of tail rotor for helicopters consisting of many narrow blades in a short duct
ferry range	safe absolute maximum distance possible when not carrying any payload
FEWSG	Fleet Electronic Warfare Support Group (USN)
FFA	Flug-und Fahrzeugwerke AG(now FFA Flugzeugwerke Altenrhein AG) (Switzerland)
FFAR	folding-fin (or free-flight) aircraft rocket
FFOS	Forward Flying Observation System
FFV	Forenade Fabriks Verke (Sweden)
FG/FS/FW	Fighter Group/Squadron/Wing (USAF)
FGA	Fighter Ground Attack (UK)
FGR	Fighter Ground Attack Reconnaissance (UK)
field length	distance needed for landing and/or take-off, normally qualified with different measurements for specific circumstances
fine pitch	setting of propeller angle most suitable for take-off and low-speed flight
FIR	Flight Information Region
FIRAMS	flight incident recorder and aircraft monitoring system
fire-and-forget missile	one with some form of self-homing capability
firewall	fire-resistant bulkhead isolating engine from rest of aircraft
fixed pitch	propeller in which blades are immovably fixed to hub, ie not variable
FL	flight level, usually expressed in hundreds of feet thus FL23 = 2,300ft
FLA	Future Large Aircraft (C-130/Transall replacement, now designated Airbus A400M)
flameout	cessation of combustion in gas turbine from cause other than fuel shutoff
flap	moveable surface forming part of trailing or leading edge of wing used for the purposes of altering low-speed lift and drag
flaperon	surface on wing trailing edge combining flap and aileron functions
flare	final nose-up pitch prior to landing to bring rate of descent to minimum (ideally, as near to zero as practical)
flat-rated	engine restricted or derated in output at sea level but able to give constant predictable power at higher altitudes or at higher ambient temperatures up to a given limit
flight envelope	basic parameters of an aircraft's performance giving the design limits of speed, altitude etc within which it must fly
FLIR	forward-looking infra-red (loosely applied to any IR-based imaging system)
flutter	high-frequency oscillation caused by interaction of aerodynamic and aeroelastic forces
fly-by-light	fibre-optically linked (as opposed to mechanical) flying control system
fly-by-wire	electrically-signalled (as opposed to mechanical) flight control system
FM	frequency modulation
FMA	Fàbrica Militar de Aviones (Argentina)
FMCS	flight management computer system
FMS	Foreign Military Sales (US)
FMS	flight management system
??FN	FN Herstal SA(Belgium)
FOB	forward operating base
FOC	full operational capability
FOD	foreign object damage
FOL	forward operating location
footprint	(1) precisely delineated area of ground, usually around an airport runway, over which noise of an aircraft must not exceed a specified level during take-off and/or landing or (2) dispersion of weapon impact points
foreplanes	pivoted canard surfaces providing authority in pitch and sometimes roll as part of primary flight control system
FOT&E	follow-on test and evaluation (US)
FOV	field of view
Fowler flap	one which initially moves rearwards to increase wing area then deflects downwards to increase drag
FR	flight refuelling
freedoms	bilateral agreements negotiated between governments relating to air traffic, first freedom is the right to fly across territory of another country with which an agreement has been made; second is the right to make a technical or non-traffic stop in that country; third is the right to set down passengers/freight in that country which were emplaned in the airline's home country; fourth is the right to pick up from that country passengers/freight destined for the airline's home country and fifth is the right to pick up from that country and carry it to a third country
free turbine	one which drives the output shaft but is mechanically independent of the compressor, thus being able to run at its own speed
frequency agile	automatically switching over a range of different frequencies to reduce the chance of eavesdropping
FRS	(1) Fleet Replenishment Squadron (USN) or (2) Fighter Reconnaissance Strike (UK)
FS/FW	Fighter Squadron/Wing (USAF)
FSAT	full-scale aerial target
FSD	full-scale development
FSS	Flight Screening Squadron (USAF)
FSW	forward-swept wing
FTS/FTW	Flying Training School (RAF, RAAF) or Squadron/Wing (USAF)
FY	fiscal year (US-- October 1 to September 30; ie FY1995 starts in October 1994)
FZ	Les Forges de Zeebrugge (Belgium)