Plain English Meaning

These are cockpit instruments that work by spinning a small wheel inside, and the wheel is kept spinning by a stream of air rather than by electricity. The spinning wheel stays steady in space, and the instrument uses that steadiness to show things like whether the wings are level or which way the nose is pointing.

Full Definition

Flight instruments that use a spinning rotor (gyroscope) driven by a flow of air to sense an aircraft's attitude, heading, or rate of turn. The air is supplied by an engine-driven vacuum or pressure pump that pulls or pushes air across small buckets cut into the rim of the rotor, spinning it at high speed. Common examples include the , , and some when configured as air-driven rather than electric.