Plain English Meaning

A mode you switch on so the autopilot will turn the aircraft to whatever direction you set with the heading bug, and then keep it pointed that way.

Full Definition

A flight director and autopilot mode that commands the aircraft to turn to and maintain a magnetic heading selected by the pilot using the heading bug on the heading indicator or HSI. When engaged, the flight director computes the bank required to capture the bug, and the autopilot (if coupled) flies the aircraft to that heading and holds it.

Context Anchor

Seen when using a flight director or autopilot, especially on the mode display after selecting a heading to fly.