Definition
A gyroscopic direction indicator that is automatically corrected (or 'slaved') to magnetic north by signals from a remote magnetic sensing element, typically a flux valve mounted in a wingtip or tail where magnetic disturbances are minimal. The gyro provides stable heading information, while the flux valve continuously nudges it back into alignment with the Earth's magnetic field, eliminating the manual resetting required of a standard directional gyro.
Plain English
A heading instrument that combines a steady gyro with a remote magnetic sensor. The sensor quietly keeps the gyro pointed correctly toward magnetic north, so the pilot doesn't have to keep adjusting it during flight.
Context Anchor
Seen in instrument flying discussions, especially with heading indicators and cockpit displays that stay automatically aligned with magnetic heading.
Derivation
Slaved' here is an engineering term meaning 'made to follow another device automatically.' One instrument (the gyro) is forced to follow the readings of another (the flux valve). It does not carry the everyday social meaning of the word.
Why Pilots Care
Reduces pilot workload by removing the need for frequent manual heading resets and provides a stable reference during instrument flight.
Intuition Check
“Slaved” does not mean the pilot is manually setting the compass. Here it means the heading display is automatically made to follow a magnetic sensor.
Example Sentence 1
Because the aircraft had a slaved compass, the pilot didn't need to manually reset the heading indicator against the magnetic compass during the flight.
Example Sentence 2
When the slaved compass showed a heading of 270, the pilot confirmed it matched the runway alignment on the approach plate.