Aeronautical Terms beginning with G
GA
General Aviation
GAMA
General Aviation Manufacturers Association.
GBAS
Ground Based Augmentation System
GDP
Ground Delay Program. Ground Delay Programs are implemented to control air traffic volume to airports where the projected traffic demand is expected to exceed the airport´s acceptance rate for a lengthy period of time. Lengthy periods of demand exceeding acceptance rate are normally a result of the airport´s acceptance rate being reduced for some reason. The most common reason for a reduction in acceptance rate is adverse weather such as low ceilings and visibility.
How it works: Flights that are destined to the affected airport are issued Expect Departure Clearance Times (EDCT) at their point of departure. Flights that have been issued EDCTs are not permitted to depart until their Expect Departure Clearance Time. These ECDTs are calculated in such a way as to meter the rate that traffic arrives at the affected airport; ensuring that demand is equal to acceptance rate. The length of delays that result from the implementation of a Ground Delay Program is a factor of two things; how much greater than the acceptance rate the original demand was, and for what length of time the original demand was expected to exceed the acceptance rate.
General Aviation
That portion of civil aviation which encompasses all facets of aviation except air carriers holding a certificate of public convenience and necessity from the Civil Aeronautics Board and large aircraft commercial operators.
GEO
Geostationary Satellite
Gimbal ring
A type of support that allows an object, such as a gyroscope, to remain in an upright condition when its base is tilted.
Glidepath Intercept Altitude
Glideslope Intercept Altitude.
Glider
A heavier-than-air aircraft, that is supported in flight by the dynamic reaction of the air against its lifting surfaces and whose free flight does not depend principally on an engine.
Glideslope Intercept Altitude
The minimum altitude to intercept the glideslope/path on a precision approach. The intersection of the published intercept altitude with the glideslope/path, designated on Government charts by the lightning bolt symbol, is the precision FAF; however, when the approach chart shows an alternative lower glideslope intercept altitude, and ATC directs a lower altitude, the resultant lower intercept position is then the FAF.
Global navigation satellite system (GNSS)
Satellite navigation system that provides autonomous geospatial positioning with global coverage. It allows small electronic receivers to determine their location (longitude, latitude, and altitude) to within a few meters using time signals transmitted along a line of sight by radio from satellites.
Global Positioning System (GPS)
A space-base radio positioning, navigation, and time-transfer system. The system provides highly accurate position and velocity information, and precise time, on a continuous global basis, to an unlimited number of properly equipped users. The system is unaffected by weather, and provides a worldwide common grid reference system. The GPS concept is predicated upon accurate and continuous knowledge of the spatial position of each satellite in the system with respect to time and distance from a transmitting satellite to the user. The GPS receiver automatically selects appropriate signals from the satellites in view and translates these into three-dimensional position, velocity, and time. System accuracy for civil users is normally 100 meters horizontally.
GLS
GNSS Landing System
GNSS
Global Navigation Satellite System.
GNSSP
Global Navigation Satellite System Panel
Go Ahead
Proceed with your message. Not to be used for any other purpose.
Go Around
Instructions for a pilot to abandon his/her approach to landing. Additional instructions may follow. Unless otherwise advised by ATC, a VFR aircraft or an aircraft conducting visual approach should overfly the runway while climbing to traffic pattern altitude and enter the traffic pattern via the crosswind leg. A pilot on an IFR flight plan making an instrument approach should execute the published missed approach procedure or proceed as instructed by ATC; e.g., “Go around” (additional instructions if required).
GPS
Global Positioning System
GPWS
Ground Proximity Warning System.
Graveyard spiral
The illusion of the cessation of a turn while still in a prolonged, coordinated, constant rate turn, which can lead a disoriented pilot to a loss of control of the aircraft.
Great circle route
The shortest distance across the surface of a sphere (the Earth) between two points on the surface.
GRI
Group Repetition Interval
Ground Clutter
A pattern produced on the radar scope by ground returns which may degrade other radar returns in the affected area. The effect of ground clutter is minimized by the use of moving target indicator (MTI) circuits in the radar equipment resulting in a radar presentation which displays only targets which are in motion.
Ground Communication Outlet (GCO)
An unstaffed, remotely controlled, ground/ground communications facility. Pilots at uncontrolled airports may contact ATC and FSS via VHF to a telephone connection to obtain an instrument clearance or close a VFR or IFR flight plan. They may also get an updated weather briefing prior to takeoff. Pilots will use four “key clicks” on the VHF radio to contact the appropriate ATC facility or six “key clicks” to contact the FSS. The GCO system is intended to be used only on the ground.
Ground Effect
A condition of improved performance encountered when an airplane is operating very close to the ground. When an airplane’s wing is under the influence of ground effect, there is a reduction in upwash, downwash, and wingtip vortices. As a result of the reduced wingtip vortices, induced drag is reduced.
Ground Loop
A sharp, uncontrolled change of direction of an airplane on the ground.
Ground proximity warning system (GPWS)
A system designed to determine an aircraft’s clearance above the Earth and provides limited predictability about aircraft position relative to rising terrain.
Ground Speed
The speed of an aircraft relative to the surface of the earth.
Ground Track
The aircraft’s path over the ground when in flight.
Ground Visibility
Prevailing horizontal visibility near the earth’s surface as reported by the United States National Weather Service or an accredited observer.
Ground Visibility [ICAO]
The visibility at an aerodrome as reported by an accredited observer.
Groundspeed
Speed over the ground, either closing speed to the station or waypoint, or speed over the ground in whatever direction the aircraft is going at the moment, depending upon the navigation system used.
GS
Ground Stop. Ground Stops are implemented for a number of reasons. The most common reasons are:
To control air traffic volume to airports when the projected traffic demand is expected to exceed the airport´s acceptance rate for a short period of time.
To temporarily stop traffic allowing for the implementation of a longer-term solution, such as a Ground Delay Program.
The affected airport´s acceptance rate has been reduced to zero.
How it works: Flights that are destined to the affected airport are held at their departure point for the duration of the Ground Stop.
GWPS
Ground Proximity Warning System.
Gyrodyne
A rotorcraft whose rotors are normally engine-driven for takeoff, hovering, and landing, and for forward flight through part of its speed range, and whose means of propulsion, consisting usually of conventional propellers, is independent of the rotor system.
Gyroplane
A rotorcraft whose rotors are not engine-driven, except for initial starting, but are made to rotate by action of the air when the rotorcraft is moving; and whose means of propulsion, consisting usually of conventional propellers, is independent of the rotor system.
Gyroscopic precession
An inherent quality of rotating bodies, which causes an applied force to be manifested 90° in the direction of rotation from the point where the force is applied.
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