ground stations is below acceptable limits.
flat rating - throttling or other restriction of engine power ouput (usually in turboprops and turboshafts) at sea level to enable it to give constant predictable power at higher operating altitudes.
flameout - combustion failure in a turbine engine resulting in power loss.
FLG - flashing.
flicker effect - nausea, dizziness or vertigo which can be brought on by flickering at certain frequencies of a bright light source such as sunlight or strobe when viewed through a rotating propeller or rotor blades.
FLIR - forward-looking infra-red.
FLM - foot-launched microlight.
FLPA - foot-launched powered aircraft, e.g. powered parachutes.
FM - frequency modulation.
FMC/S - flight management computer/system
FMGC - flight management guidance computer.
FMS - flight management system.
FMU - flight management unit.
FOD - foreign object damage, usually to turbine engines through ingestion of runway debris etc.
FPL - filed flight plan.
fpm - feet per minute, a measure of an aircraft\or descent. Similarly m/s or mps, metres per second.
FSS - Flight Service Station (USA).
FTO - flying training organisation.
FTS - Flying Training School (RAF)
ft/min - feet per minute
G
g - the acceleration force of gravity, normally 1g on earth. Zero g (0g) is weightlessness, as experienced by orbiting astronauts. g is expressed as positive (\\) and negative (-) values. During a normal loop a pilot experiences positive g, tending to force him down in his seat. In an outside loop, with the pilot\on the outside of the vertical circle, negative g forces him up against his straps. Aircraft structural load limits are expressed in positive and negative values, the positive limit usually greater than negative, except in specialist aerobatic types.
g-loc - g-induced loss of consciousness. Pilot blackouts caused by excessive g or by too-rapid onset of g-forces. Experienced mostly by pilots of high-perＦＯＲＭance military jets and competition aerobatic aircraft, has led to fatal crashes.
GA - general aviation, all flying other than airlines and the military.
GAAC - General Aviation Awareness Campaign.
GAFOR - General Aviation Visual Flight Forecast. Met briefing service in operation in France, Germany, the Netherlands and some other European countries.
gall imp/U.S. - gallons, imperial or USA. One imp gall = 1.201 U.S. gall.
GAMA - General Aviation Manufacturers Association, an American trade organisation.
GAMTA - General Aviation Manufacturers & Traders Association, UK.
GAPAN - Guild of Air Pilots and Air Navigators.
GASCo - General Aviation Safety Council
GASIL - General Aviation Safety InＦＯＲＭation Leaflet. Monthly safety and accident prevention bulletin for pilots and engineers published by the CAA.
GCA - ground-controlled approach. A landing approach in which a ground controller gives verbal guidance in azimuth and elevation to a pilot using precision approach radar (PAR) to monitor the aircraft\
GFT - General Flying Test, taken by student pilots to qualify for the PPL, and also by candidates for the BCPL and CPL. Also NFT, navigation flight test, which is part of the practical examination for the PPL.
Glonass - Russian equivalent of GPS/Navstar satellite navigation system.
glove - non-movable part of a variable geometry wing.
gnd - ground
GNSS - Global Navigation Satellite Systems.
go-around to climb away from a runway after making an approach, either to make a further attempt at landing or to divert to an alternate airport (ＦＯＲＭerly \
Goxio - VHF direction-finding (France)
GP - glidepath
gph - gallons per hour, an expression of fuel consumption or fuel flow (FF) in either imperial or U.S. gallons. Usually lb/hr for turbine-powered aircraft.
GPS - Global Positioning System (Navstar). A U.S. developed satellite-based high-precision navigation system, intended primarily for military use but now in widespread use by commercial and private operators, though with reduced accuracy compared with military versions.
GPWS - ground proximity warning system. A radar-based flight- deck system to give pilots audible warning by means of horns, hooters, taped or synthetic voices of terrain close beneath an aircraft\
GRADU - gradual (term used in Met reports).
GRP - glassfibre-reinforced plastic; also CFRP, carbon-fibre reinforced plastic. Composite materials seeing increasing use in entire airframes for GA aircraft (e.g. Beech Starship) and for components for helicopters, airliners and military aircraft.
GS - glideslope. The vertical guidance part of an instrument landing system which establishes a safe glidepath (usually three degrees) to a runway.
G/S - groundspeed. The speed an aircraft makes over the ground, a product of its airspeed and wind speed. H
H24 - continuous round-the-clock operation. Also HJ operates during day; HN operates during night; HO operates during times to meet operational requirements, and HX no specific operational hours.
HAA - Historic Aircraft Association.
HAI - Helicopter Association International.
half-mill(ion) - 1:500,000 scale ICAO aeronautical chart.
Hdg - heading. The direction in which an aircraft\nose points in flight in the horizontal plane, expressed in compass degrees.
Heavy - suffix used in RT callsigns to indicate that the aircraft is a large transport, alerting controllers and following aircraft to the possibility of wake turbulence .
Hectopascal (hPa) - unit of pressure measurement, equivalent to one millibar (which see), now the ICAO-standard for altimeter setting.
HEMS - helicopter emergency medical services.
Hertz - standard radio equivalent of frequency in cycles per second. See also kHz and MHz.
HF - high-frequency band, used for long-range radio communications in the 3-30 MHz range.
Hg - inches of mercury, a unit of pressure measurement.
HIAL - high intensity approach lighting.
HIGE - hover in ground effect. Also see HOGE.
HIRF - high intensity radiated (electromagnetic) fields.
HIRL - high intensity runway lighting.
HISL - high intensity strobe light.
holding pattern - racetrack-shaped manoeuvre which keeps aircraft within a specified airspace while awaiting further clearance from air traffic control.
HOCAC - hands on cyclic and collective - see HOTAS below.
HOGE - hover out of ground effect. Also see HIGE.
hot-and-high - airfield conditions of high altitude and high ambient temperatures that can severely limit aircraft perＦＯＲＭance. See also density altitude.
HOTAS - hands on throttle and stick. Ergonomic cockpit design technology, originally developed for military combat aircraft, enabling a pilot to fly the aircraft and manage all navigation, weapons and other systems from control column/throttle lever hand grips.
HOTCC - hands on throttle, collective & cyclic - see HOTAS above.
hp - horsepower.
HRA - Highlands Restricted Area
hrs - hours
HSD - horizontal situation display.
HSI - horizontal situation indicator. A cockpit navigation display, usually part of a flight-director system, which combines navigation and heading.
HUD - head-up display. A method of projecting instrument readouts or data which enables a pilot to see them while looking through the aircraft\windscreen. Mostly used on military aircraft, but now in service on some commercial airliners.
Hz - Hertz.
I
IAOPA - International Council of Aircraft Owners and Pilots Associations
IAS - indicated airspeed. An aircraft\correction for position error, altitude or outside air temperature. Also see CAS, RAS and TAS.
IATA - International Air Transport Association.
i/c - intercom
ICAO - International Civil Aviation Organisation.
IF - instrument flying. Also intermediate frequency.
IFF - identification friend or foe.
IFR - instrument flight rules prescribed for the operation of aircraft in instrument meteorological conditions (see below). Flight in most controlled airspace in the UK is conducted under IFR or Special VFR. Also used by military to denote in-flight refuelling.
IGE - in ground effect. Helicopter perＦＯＲＭance with an earth surface immediately below. Also OGE, out of ground effect. Helicopters can hover at a greater maximum altitude IGE (above a mountain slope, for example) than they can in free air, OGE.
IGS - instrument guidance system.
