Aeronautical Terms beginning with G
G/S
Glide Slope
GA
General Aviation
GA CDR
General Aviation Coded Departure Routes (GA CDR) - The CDR program provides a rapid means to reroute aircraft when the filed route is constrained by either weather or congestion. Historically, abbreviated CDR clearances have only been issued to airline customers who have signed a Memorandum of Agreement (MOA) with the facilities that issue abbreviated CDR clearances. Recently, general aviation customers have requested the use of this reroute capability. This change permits general aviation customers to communicate to Air Traffic Control (ATC) facilities their ability and willingness to accept CDRs and their capability to accept abbreviated clearances associated with CDRs. Please see the GA CDR Advisory circular for more details.
GAMA
General Aviation Manufacturers Association
GAMA
General Aviation Manufacturers Association.
Gas Generator
The basic power producing portion of a gas turbine engine and excluding such sections as the inlet duct, the fan section, free power turbines, and tailpipe. Each manufacturer designates what is included as the gas generator, but generally consists of the compressor, diffuser, combustor, and turbine.
Gas Turbine Engine
A form of heat engine in which burning fuel adds energy to compressed air and accelerates the air through the remainder of the engine. Some of the energy is extracted to turn the air compressor, and the remainder accelerates the air to produce thrust. Some of this energy can be converted into torque to drive a propeller or a system of rotors for a helicopter.
Gate Hold Procedures
Procedures at selected airports to hold aircraft at the gate or other ground location whenever departure delays exceed or are anticipated to exceed 15 minutes. The sequence for departure will be maintained in accordance with initial call-up unless modified by flow control restrictions. Pilots should monitor the ground control/clearance delivery frequency for engine start/taxi advisories or new proposed start/taxi time if the delay changes.
Gateway Fix
A navigational aid or fix where an aircraft transitions between the domestic route structure and the oceanic route airspace.
GBAS
Ground Based Augmentation System
GBT
Ground-Based Transmitter
GCA
Ground Controlled Approach
GCO
Ground Communication Outlet
GDP
Ground Delay Programs
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.
GDPE
Ground Delay Program Enhancements
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
Geodetic Datum
The reference plane from which geodetic calculations are made. Or, according to ICAO Annex 15, the numerical or geometrical quantity or set of such quantities (mathematical model) that serves as a reference for computing other quantities in a specific geographic region such as the latitude and longitude of a point.
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.
Glaze
A coating of ice, generally clear and smooth, formed by freezing of super.cooled water on a surface.
Glide Ratio
The ratio between distance traveled and altitude lost during non-powered flight.
Glide slope (GS)
Part of the ILS that projects a radio beam upward at an angle of approximately 3° from the approach end of an instrument runway. The glide slope provides vertical guidance to aircraft on the final approach course for the aircraft to follow when making an ILS approach along the localizer path.
Glide slope intercept altitude
The minimum altitude of an intermediate approach segment prescribed for a precision approach that ensures obstacle clearance.
Glidepath
The path of an aircraft relative to the ground while approaching a landing.
Glidepath Angle (GPA)
The angular displacement of the vertical guidance path from a horizontal plane that passes through the reference datum point (RDP). This angle is published on approach charts (e.g., 3.00, 3.20, etc.). GPA is sometimes referred to as vertical path angle (VPA).
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 (GS)
Part of the ILS that projects a radio beam upward at an angle of approximately 3° from the approach end of an instrument runway. The glideslope provides vertical guidance to aircraft on the final approach course for the aircraft to follow when making an ILS approach along the localizer path.
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 landing system (GLS)
An instrument approach with lateral and vertical guidance with integrity limits (similar to barometric vertical navigation (BRO VNAV).
Global Navigation Satellite System (GNSS)
An umbrella term adopted by the International Civil Aviation Organization (ICAO) to encompass any independent satellite navigation system used by a pilot to perform onboard position determinations from the satellite data.
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)
Navigation system that uses satellite rather than ground-based transmitters for location information.
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
Global Navigation Satellite System Landing System
GLS
GNSS Landing System
GLS
Global Landing System.
GNE
Gross Navigation Error
GNSS
Global Navigation Satellite Systems.
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).
Go-around power or thrust setting
The maximum allowable in-flight power or thrust setting identified in the performance data.
Goals and values
A perception factor that describes how a person’s perception of an event depends on beliefs. Motivation toward learning is affected by how much value a person puts on education. Instructors who have some idea of the goals and values of their students will be more successful in teaching them.
Goniometer
As used in radio frequency (RF) antenna systems, a direction-sensing device consisting of two fixed loops of wire oriented 90 from each other, which separately sense received signal strength and send those signals to two rotors (also oriented 90) in the sealed direction-indicating instrument. The rotors are attached to the direction-indicating needle of the instrument and rotated by a small motor until minimum magnetic field is sensed near the rotors.
Goniometer
As used in radio frequency (RF) antenna systems, a direction-sensing device consisting of two fixed loops of wire oriented 90° from each other, which separately sense received signal strength and send those signals to two rotors (also oriented 90°) in the sealed direction-indicating instrument. The rotors are attached to the direction-indicating needle of the instrument and rotated by a small motor until minimum magnetic field is sensed near the rotors.
Governing Range
The range of pitch a propeller governor can control during flight.
Governor
A control which limits the maximum rotational speed of a device.
GPS
Global Positioning System.
GPS
Global Positioning System
GPS Approach Overlay Program
An authorization for pilots to use GPS avionics under IFR for flying designated existing nonprecision instrument approach procedures, with the exception of LOC, LDA, and SDF procedures.
GPWS
Ground Proximity Warning System
GPWS
Ground Proximity Warning System.
Gradient
In meteorology, a horizontal decrease in value per unit distance of a parameter in the direction of maximum decrease; most commonly used with pressure, temperature, and moisture.
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.
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.
Great circle route
The shortest distance across the surface of a sphere (the Earth) between two points on the surface.
GRI
Group Repetition Interval
Gross Navigation Error (GNE)
In the North Atlantic area of operations, a gross navigation error is a lateral separation of more than 25 NM from the centerline of an aircrafts cleared route, which generates an Oceanic Navigation Error Report. This report is also generated by a vertical separation if you are more than 300 feet off your assigned flight level.
Gross Weight
The total weight of a fully loaded aircraft including the fuel, oil, crew, passengers, and cargo.
Ground Adjustable Trim Tab
A metal trim tab on a control surface that is not adjustable in flight. Bent in one direction or another while on the ground to apply trim forces to the control surface.
Ground clutter
Pertaining to radar, a cluster of echoes, generally at short range, reflected from ground targets.
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 Controlled Approach
A radar approach system operated from the ground by air traffic control personnel transmitting instructions to the pilot by radio. The approach may be conducted with surveillance radar (ASR) only or with both surveillance and precision approach radar (PAR). Usage of the term “GCA” by pilots is discouraged except when referring to a GCA facility. Pilots should specifically request a “PAR” approach when a precision radar approach is desired or request an “ASR” or “surveillance” approach when a nonprecision radar approach is desired.
Ground Delay Program (GDP)
A traffic management process administered by the ATCSCC; when aircraft are held on the ground. The purpose of the program is to support the TM mission and limit airborne holding. It is a flexible program and may be implemented in various forms depending upon the needs of the AT system. Ground delay programs provide for equitable assignment of delays to all system users.
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 fog
In the United States, a fog that conceals less than 0.6 of the sky and is not contiguous with the base of clouds.
Ground Idle
Gas turbine engine speed usually 60-70 percent of the maximum r.p.m. range, used as a minimum thrust setting for ground operations.
Ground Loop
A sharp, uncontrolled change of direction of an airplane on the ground.
Ground Power Unit (GPU)
A type of small gas turbine whose purpose is to provide electrical power, and/or air pressure for starting aircraft engines. A ground unit is connected to the aircraft when needed. Similar to an aircraft-installed auxiliary power unit.
Ground proximity warning system (GPWS)
A system designed to determine an aircrafts clearance above the Earth and provides limited predictability about aircraft position relative to rising terrain.
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 Stop (GS)
The GS is a process that requires aircraft that meet a specific criteria to remain on the ground. The criteria may be airport specific, airspace specific, or equipment specific; for example, all departures to San Francisco, or all departures entering Yorktown sector, or all Category I and II aircraft going to Charlotte. GSs normally occur with little or no warning.
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
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.
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.
Groundspeed Measurement System
A measurement system for determining the groundspeed of an aircraft during final approach and landing, by measuring at the aircraft the Doppler shift of a radio signal, and/or its modulation components, transmitted by a fixed ground station.
GS
Glide Slope.
GS
Groundspeed
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.
GSD
Geographical Situation Display
Guided discussion method
An educational presentation typically used in the classroom where the topic to be covered by a group is introduced and the instructor participates only as necessary to keep the group focused on the subject.
GUS
Ground Uplink Station
Gust
A sudden brief increase in wind; according to U.S. weather observing practice, gusts are reported when the variation in wind speed between peaks and lulls is at least 10 knots.
Gust Penetration Speed
The speed that gives the greatest margin between the high and low mach speed buffets.
GWPS
Ground Proximity Warning System.
GWPS
Ground Proximity Warning System.
GWS
Graphical Weather Service
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 90º in the direction of rotation from the point where the force is applied.
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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