Aeronautical Terms beginning with H

Head-up display (HUD)

A special type of flight viewing screen that allows the pilot to watch the flight instruments and other data while looking through the windshield of the aircraft for other traffic, the approach lights, or the runway.

HF Communications

High Frequency Communications.

High Frequency

The frequency band between 3 and 30 MHz.

High Frequency Communications

High radio frequencies (HF) between 3 and 30 MHz used for air-to-ground voice communication in overseas operations.

Highway in the Sky (HITS)

A graphically intuitive pilot interface system that provides an aircraft operator with all of the attitude and guidance inputs required to safely fly an aircraft in close conformance to air traffic procedures.

Hot Start

In gas turbine engines, a start which occurs with normal engine rotation, but exhaust temperature exceeds prescribed limits. This is usually caused by an excessively rich mixture in the combustor. The fuel to the engine must be terminated immediately to prevent engine damage.

Hung Start

In gas turbine engines, a condition of normal light off but with r.p.m. remaining at some low value rather than increasing to the normal idle r.p.m. This is often the result of insufficient power to the engine from the starter. In the event of a hung start, the engine should be shut down.