Pilot/Controller Glossary

GROSS NAVIGATION ERROR (GNE) - A lateral deviation of 10 NM or more from the aircraft"s cleared route.
GROUND BASED AUGMENTATION SYSTEM (GBAS)" A ground based GNSS station which provides
local differential corrections, integrity parameters and approach data via VHF data broadcast to GNSS users to
meet real-time performance requirements for CAT I precision approaches. The aircraft applies the broadcast data
to improve the accuracy and integrity of its GNSS signals and computes the deviations to the selected approach.
A single ground station can serve multiple runway ends up to an approximate radius of 23 NM.
GROUND BASED AUGMENTATION SYSTEM (GBAS) LANDING SYSTEM (GLS)- A type of precision
IAP based on local augmentation of GNSS data using a single GBAS station to transmit locally corrected GNSS
data, integrity parameters and approach information. This improves the accuracy of aircraft GNSS receivers"
signal in space, enabling the pilot to fly a precision approach with much greater flexibility, reliability and
complexity. The GLS procedure is published on standard IAP charts, features the title GLS with the designated
runway and minims low as 200 feet DA. Future plans are expected to support Cat II and CAT III operations.
GROUND-BASED INTERVAL MANAGEMENT-SPACING (GIM-S), SPEED ADVISORY- A calculated
speed that will allow aircraft to meet the TBFM schedule at en route and TRACON boundary meter fixes.
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.
(See CLUTTER.)

GROUND COMMUNICATION OUTLET (GCO)- An unstaffed, remotely controlled, ground/ground
communications facility. Pilots at uncontrolled airports may contact ATC and FSS via VHF radio to a telephone
connection. If the connection goes to ATC, the pilot can obtain an IFR clearance or close an IFR flight plan. If
the connection goes to Flight Service, the pilot can open or close a VFR flight plan; obtain an updated weather
briefing prior to takeoff; close an IFR flight plan; or, for Alaska or MEDEVAC only, obtain an IFR clearance.
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.
(See RADAR APPROACH.)

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 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 VISIBILITY-
(See VISIBILITY.)

GS-
(See GROUND STOP.)