the Aviation Dictionary

information. Grid MORA values followed by a denote
doubtful accuracy, but are believed to provide
sufficient reference point clearance. 2.) Grid MORA
(State) altitude supplied by the State Authority
provides 2000 feet clearance in mountainous areas and
1000 feet in nonmountainous areas.
grind - The process of removing metal from a part with
an abrasive stone or wheel.
grinder - A machine with an abrasive wheel used to
remove material from a part.
grinding wheel - An abrasive wheel used on grinders to
remove excess material.
grip length - The length of the unthreaded shank of a
bolt. Also, the length of a blind rivet between the
manufactured head and the maximum extent of the
pulled head. It is the maximum thickness of material
that can be joined by a fastener.
grind ground power unit
ground communication outlet (GCO) - An unstaffed,
remotely controlled, groundlground 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 s~ecifically request a
grip range - The difference between the maximum and "PAR approach when a radar approach is
minimum thickness of material that may be joined by a desired or request an "ASR" or "surveillance"
fastener.
approach when a nonprecision radar approach is
grit blasting - A process for cleaning metal in which
abrasive materials such as sand, rice, baked wheat,
plaster pellets, glass beads, or crushed walnut shells are
desired.
ground crew - The people who maintain, service, and
prepare the aircraft before and after flight.
forcefully blown onto the part's surface.
grommet - 1. A metal or plastic eyelet used for
reinforcing holes in aircraft fabric. 2. A small ring of
metal, rubber, or plastic used as a fairlead and protector
for tubing or wire going though a hole in a metal
structure.
grooved surface - A shallow, smooth channel wider
than a scratch resulting - from wear caused by
concentrated 'Ontact
movement between contact surfaces or by foreign
material on contact surfaces creates the contact stress.
The parts usually affected include cylinder barrels,
valve faces, and oil seal outer sleeves.
gross thrust - The thrust developed by an engine, not
taking into consideration any pressure of initial air
massrnomentum. Also referred to as static thrust (Fg).
gross weight - The total weight of a filly loaded aircrafl
including the fuel, oil, and cargo it is carrying.
ground delay - The amount of delay attributed to ATC,
encountered prior to departure, usually associated with
a CDT program.
ground effect - The condition of slightly increased air
pressure below an airplane wing or helicopter rotor
system that increases the amount of lift produced. It
exists within approximately one-half wing span or
one-half of the rotor diameter from the ground.
ground fog - In the United States, a fog that is generally
less than 20 feet deep
ground idle - A gas turbine engine speed usually in the
60% to 70% of the maximum RPM range, used as a
minimum thrust setting for ground operations.
ground loop - 1. The sudden reversal of direction of
travel on the ground of an airplane having a tailwheeltype
landing gear. The center of gravity swings around
ahead of the wheels. 2. An undesirable flow of
electrical current through the braid around a shielded
ground - 1. A reference point for voltage measurement wire.
in an circuit' 2' To 'Onnect a part Or ground plane - The reflector used in a
component to the electrical ground (normally the
radio antenna. Serves as an additional quarter-wave
airframe).
element.
ground 'Iutter - 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.
Aircraft Technical Book Company
P.O. Box 270
Tabernash, CO 80478
http:llwww.ACTechbooks.com
ground potential - The zero potential (no voltage
difference) of electrical circuits.
ground power unit - A small gas turbine whose
purpose is to provide either electrical power, air
pressure for starting aircraft engines, or both. A ground
- A