Plain English Meaning

A heading instrument that uses a spinning gyro for steady, smooth indication, but quietly keeps itself synced to magnetic north using a magnetic sensor somewhere on the aircraft. The pilot doesn't have to keep correcting it.

Full Definition

A heading indicator whose gyroscope is automatically corrected by a remote magnetic sensor (typically a flux gate or flux valve mounted in a wingtip or tail), so the displayed heading stays aligned with magnetic north without the pilot manually resetting it.

Context Anchor

Seen during the after-engine-start instrument check, when the pilot verifies that the heading is aligned and operating normally before .