getter. A small piece of alkaline metal placed inside an electron tube (vacuum tube) when it is manufactured. When the tube is completed and the air evacuated from it, current is passed through the getter which raises its temperature enough to melt it, causing it to react with any oxygen left inside the tube. The silvery deposit often seen inside the glass tube envelope is the residue from the getter.
GHz (gigahertz). One billion (1,000,000,000) cycles per second.
giga. The metric prefix that means billion.
gilbert. A unit of magnetomotive force. One gilbert is equal to the force produced by an electromagnet of 0.7957 ampere-turn. The constant 0.7957 is found by dividing 10 by 4 π.
gill-type cowl flap (reciprocating engine cowling component). A small flap located at the rear of the cowling for a reciprocating engine. Opening the cowl flap increases the amount of cooling air flowing through the engine by decreasing the pressure at the point the air leaves the engine compartment.
gimbal. A type of support that allows an object, such as a gyroscope, to remain in an upright condition when its base is tilted. Gyroscopes used in certain aircraft flight instruments are mounted in gimbals. Some in single gimbals, and others in double gimbals. The gyro in a turn and slip indicator is mounted in a single gimbal, and it senses rotation only about the vertical axis of the aircraft. The gyro in an attitude gyro instrument is mounted in a double gimbal, and it senses rotation about both the lateral and the longitudinal axes.

gimlet point (threaded fastener). A threaded, cone-shaped point on self-tapping sheet metal screws that are installed through holes in several sheets of thin sheet metal.

glass cloth. Cloth woven from glass fibers. Glass cloth can be impregnated with a thermosetting resin and cured in a mold to produce complex-shaped aircraft structural components.
glass cockpit. An aircraft instrument system that uses a few multicolor cathode-ray-tube displays to replace a large number of mechanically actuated instruments.
glass fiber. A filament, or thread, of glass, usually less than one-thousandth of an inch (25 micrometers) in diameter. Glass fibers, woven into cloth or packed together into a mat, are used for thermal and acoustical insulation and for reinforcing plastic resins to make various types of molded products.
glaze (aircraft brake malfunction). A hard, glass-like coating that forms on the brake disk surface. The friction caused by the glazed surface is not uniform, and when the brakes are applied, they grab and release at such a high rate that they chatter or squeal. The glazed surface must be removed from a disk for the braking to be effective.