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ground return
rotor; potentially catastrophic unless designed out, and
even with certificated helicopter can occur as a result of
severe landing shock.
ground return See ground clutter.
ground roll Distance travelled from point of touchdown
to runway turnoff, stopping or other point marking end
of landing.
ground run Distance from brake-release to unstick, not
same at TOR (see takeoff).
ground safety lock Retraction lock.
groundschool This is increasingly being spelt as one
word. It usually refers to classroom instruction for GA
pilots, especially on executive aircraft.
ground sheet Radial-wall flow of hot gas along ground
beneath VTO [esp. jet-lift] hovering in ground effect.
ground signals Bold visual symbols displayed in signal
area.
groundspeed, G/S Aircraft speed relative to local Earth.
groundspeed mode Flight-system mode holding constant
G/S.
ground spoiler Spoiler available only after landing,
usually as lift dumper.
ground start Supply of propellants to large rocket
vehicle from ground during ignition and hold-down so
that at liftoff main-stage tanks are still full.
ground stop Holds flight [usually scheduled, but in any
case already cleared] at departure. Reasons might be
closure of destination or to allow for implementation of
longer-term solution to a destination problem, such as a
GDP.
ground strafing Attack by aircraft on tactical surface
target, esp. by gunfire.
ground support 1 Air power deployed for immediate
assistance of friendly army, ie close air support; hence
designation * aircraft.
2 Hardware needed to facilitate operation of aircraft,
eg ladders, chocks, refuelling, replenishing and rearming
equipment, loaders, tie-downs, blanks (4) and ground
conditioning and power supplies; and use thereof.
ground support equipment, GSE Ground equipment
required for operation of aircraft [especially military],
RPV or missile.
ground swing envelope Plot of ground where obstructions
would foul nose or tail of longest aircraft in most
extreme positions on curves of taxiways or apron.
ground test Test on ground of equipment or system
normally used in air.
ground test coupling Connections enabling airborne
system to be tested on ground for fluid pressure and
functioning, supply voltage or any other variable.
ground trace Ground track of satellite.
ground track Path on Earth’s surface vertically below
aircraft or satellite.
ground upset Accident caused to light aircraft or other
vehicle by jet blast or large propeller slipstream.
ground visibility Prevailing visibility along Earth’s
surface as reported by accredited observer or measured by
RVR.
groundwash Outward flow of wake turbulence from
engines or wingtips of large aircraft on ground.
ground wave Radio or other EM waves taking direct
path from ground transmitter to ground receiver (in practice
mix of ground, ground-reflected and surface waves);
subject to refraction in ducts in troposphere.
GSC
ground wire 1 US term for earthing wire.
2 Winched cable emerging from top of mooring mast
and connected to airship mooring cable; US = mast line.
ground zero, GZ Point on Earth nearest to centre of
nuclear detonation (which may be below, at or above
GZ).
group 1 Military air formation consisting of two or
more squadrons (DoD), or two or more wings (RAF).
2 Several sub-carrier oscillators in telemetry system.
3 Major portion of aircraft (eg. wing*) assigned to * (4).
4 Team of engineers assigned to design, stress, develop
and possibly cost major portion of aircraft, often
remaining intact to work on same part on successive
programmes; common in US, where * titles are wing, fuselage,
tail/controls, weight, electrical, hydraulic, armament
and often others.
group flashing light, GpFL Ground light with regular
emission of two or more flashes or Morse letter(s).
group technology General term for philosophy that links
CAD with CAM to give CIM, based on recognising similarities
between discrete parts.
group velocity Symbol U, that of entire disturbance of
waves, equal to phase speed c minus wavelength 1 times
dc/dl.
growl Missile tone heard in pilot headset indicating IR
head locked on to target.
growler 1 Test equipment for short circuits in electrical
machines (colloq.).
2 ECM aircraft, or a member of its crew.
growth Development to increase performance, hence *
engine; this may or may not be physically larger.
GRP 1 Glass-reinforced plastics.
2 Geographic reference point.
GRR Glycol recovery and recycling.
GRS 1 Government rubber synthetic, Buna-S type.
2 Global reconnaissance strike (US).
3 Gamma-ray spectrometer.
GRSF Ground Radio Servicing Flight (RAF).
GRT Gross registered tonnage, measure of capacity of
ship, = 100 ft 3 = 2.832 m 3 .
GRU Main intelligence directorate of General Staff
(USSR).
grunt manoeuvre One involving high g (colloq.).
Gruppe Group (G), equivalent to RAF wing.
GRV Glycol recovery vehicle.
GRVD Grooved runway.
GRVL Gravel runway or surface.
Gr wt Gross weight.
Gryphon FBMS/shore communications system.
GS 1 Ground speed.
2 Glideslope.
3 Ground plus station (costs).
4 Ground supply (usually electrical).
5 General schedule.
6 Galley service vehicle.
7 Ground stop.
8 Gliding School.
G/S 1 Ground speed.
2 Glideslope.
Gs Small hail or snow pellets.
GSA Gunsight, surface-to-air.
GSARS Ground-surveillance airborne radar system.
GSC 1 Ground switching centre.
2 Ground-station controller.
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