Plain English Meaning

An instrument that shows your heading using a spinning gyroscope instead of a magnet, so it stays steady and isn't fooled by the things that disturb a magnetic compass.

Full Definition

A direction-indicating instrument that uses a gyroscope to maintain a stable heading reference, aligned to a fixed direction such as true north or a heading set by the pilot, independent of the Earth's magnetic field.

Context Anchor

Seen in instrument navigation discussions, especially when an ADF bearing pointer is shown on an RMI instead of on a fixed compass card.

Derivation

From '' (Greek '', meaning a turn or ) and '' (a direction-finding instrument). The name reflects that direction is held by a spinning wheel rather than by .