Definition
Manual control buttons on a remote indicating compass system (such as the slaved gyro compass) used to rotate the compass card and align it with the correct magnetic heading when the slaving system is switched to free gyro mode or requires manual correction.
Plain English
Buttons that let the pilot turn the compass card by hand to set it to the right heading when the system is not automatically keeping it aligned.
Context Anchor
Seen in discussions of remote indicating compass systems and cockpit heading displays that can be adjusted manually.
Derivation
In this term, “drive” means “to cause something to move,” not to steer or taxi the airplane. The buttons drive, or move, the heading display.
Why Pilots Care
Keeps the heading indicator accurate so the pilot can fly precise courses without constantly cross-checking the wet compass.
Intuition Check
These buttons do not turn the airplane. They turn the heading indication on the instrument.
Example Sentence 1
After switching to free gyro mode, the pilot used the heading-drive buttons to align the compass card with the magnetic compass reading.
Example Sentence 2
She pressed the heading-drive buttons to set the new course before entering the holding pattern.