F2E – Fitter II (Engines)
FA – Flying Accident

FAA – Fleet Air Arm

“Fan” - Propeller
FAGS – Fleet Aerial Gunners School
FATU – Flight Affiliation Training Unit/Fighter Armament Training Unit
FB – Flying Battle (Damage)

FBDF – Flying Boat Development Flight
F–BFTS – France–Belgium Flying Training Unit
FBSU – Flying Boat Servicing Unit
FBSU – Flying Boat Servicing Unit
FC – Ferry Control / Fighter Command / Flying Control
FCCRS – Fighter Command Control & Reporting School
FCCS/F Fighter Command Communication Squadron/Flight
FCCU – Fighter Control Cooperation Unit
FCIRS/F – Fighter Command Instrument Rating Squadron/Flight
FCITF/S – Fighter Command Instrument Training Flight .Squadron
FCMPC – Fighter Command Missile Practice Camp
FCPU – Ferry Command Preparation Unit
FCRS – Fighter Command Radar School
FCS – Fighter Command School /  Facility Checking Squadron

FCTS – Fighter Controllers Training School
FCTU – Fighter Command Trials Unit
FDF – Fighter Defence Unit
F/E – Flight Engineer
FE – Far East
FEAF – Far East Air Force
FEAFES – Far East Air Force Examination Squadron

FEC – Far East Command
FECEF – Far East Casualty Evacuation Unit
FEE – Fighter Experimental Establishment
FEFEW – Far East Flying Boat Wing
FETDU – Far East Tactical Development Unit
FETS – Far East Training Squadron
FETW – Far East Training Wing
FF – Fighter Flight/Ferry Flight/Free French
FFAF – Free French Air Force
FFDPF – Free French Desert Patrol Flight
FFFF – Free French Fighter Flight

FFS – Fire Fighting School

FFU – Film Flight Unit
FIDO – Fog Investigation and Dispersal Operation

F I DS/U – Fighter Interception Development Squadron/Unit
"(Mr.) Fireworks" – Armaments Officer

FIS – Flying Instructors School
F I U – Fighter Interception Unit
F/L – Forced Landing

F/L or Flt Fl – Flight Lieutenant

“Flak” – Anti-Aircraft Fire (artillery)

"(to) Flannel" – To seek favour by fawning

"Flap" – A disturbance or Other general excitement

"(in a) Flat Spin" –  Complete confused

"Flat Out" –  Complete exhausted

Flot – Flotilla
FLS – Fighter Leaders School
Flt – Flight
Flt Cdr – Flight Commander

FM(A) –Flight Mechanic (Airframes)
FM(E) - Flight Mechanic (Engines)
F/O or Fl O  – Flying Officer
FP – Ferry Pool
FPDU – Field Punishment and Detention Centre

FPP/U – Ferry Pilots Pool   / U
FPU – Ferry Preparation Unit / Film Production Unit
FR – Fighter–reconnaissance
FRD – Forward Repair Depot
FRS – Flying Refresher School
FRU – Field Repair Unit/Fleet Requirements Unit
F/S or F/Sgt. – Flight Sergeant
FS – Fighting School
FSAF&G – Fleet School of Aerial Fighting & Gunnery School
FSDS – Fighter Support Development Squadron
FSP – Forward Staging Post
FSS – Ferry Support Squadron/Flying Selection Squadron
FSTU – Fighter Support Training Unit
FT – Flying Training

FTC – Flying Training Command
FTCPF – Flying Training Command Practice Flight
FTF/U – Ferry Training Flight/Unit
FTFlt – Ferry Training Flight
FTLU – French Tactical Liaison Unit
FTR – Failed to Return
FTS – Flying Training School
FTU – Ferry Training Unit/Floatplane Training Unit/Flight Trials Unit
FU – Ferry Unit
FWS – Fighter Weapons School
F w – Feldwebel/Focke Wulfe

“Gone For A Burton" – Air Crew whose has been killed

“Gong” – Medal

“Got the chop” – a person that was killed (usually in action)

GOTU – Glider Operational training Unit

Gp or Grp – Group
G/C or Gp Capt or "Groupy" – Group Captain

GP – General Purpose
GP CF – Group Conversion Flight
GP/DA – Group Disposal Account (book–keeping exercise for damaged aircraft)
GPEU – Glider Exercise Unit
GPIS – Glider Pilot Instructors School
GPUTF – Glider Pick–Up Training Unit
GPR – Glider Pilot Regiment
GR – General reconnaissance
GR&ANS – General Reconnaissance and Air Navigation School
"Gravey" – Petrol or Gasoline

"Greenhouse" – Cockpit cover

"Gremlins" – The "little men" of the RAF or Imaginary figure that causes something to go wrong

"Grocers" – Suppliers

GRS – General Reconnaissance School
GRU – General Reconnaissance Unit
GRU/F – General Reconnaissance Unit/Flight
GS – Gliding School
GS – Grading School
GSE – Glider Servicing Echelon
GSF – Glider Servicing Flight

GSM – General Service Medal
GSU – Group Support Unit

GSTS – General Service Training Shcool
GTF – Gunnery Training Flight
GTPS – Glider & Tug Pilots School
GTS – Glider Training Squadron/Glider Training School
GU – Grading Unit
GUAS – Glasgow University Air Squadron
GWDS – Guided Weapon Development Squadron
GWTS – Guided Weapon Training Squadron