Definition 1 of 2
Definition
A directional gyro whose heading indication is automatically corrected by reference to a remote magnetic sensor (typically a flux valve or flux gate mounted in a wingtip or tail). The gyro provides the stable, drift-free heading signal, while the magnetic sensor continuously nudges it back into alignment with magnetic north, eliminating the manual resetting required by a free (unslaved) directional gyro.
Plain English
A heading instrument that combines a steady gyroscope with a magnetic compass sensor. The sensor quietly keeps the gyro lined up with magnetic north, so the pilot doesn't have to keep re-setting it.
Context Anchor
Seen in cockpit heading systems, especially aircraft with remote compass systems or instrument panels that display heading from a gyro-based instrument.
Derivation
Slaved' here means 'made to follow' — one device is forced to track another. The gyro is 'slaved' to the magnetic sensor, meaning it follows whatever heading the sensor reports as magnetic north.
Why Pilots Care
It eliminates frequent manual resets of the directional gyro, reducing workload and preventing navigation errors from heading drift.
Analogy
It is like a clock that keeps itself matched to an outside time signal. The clock still runs on its own, but the outside reference keeps it from slowly drifting off.
Intuition Check
“Slaved” does not mean the gyro is weaker or less important. Here it means the gyro is automatically corrected by another reference.
Example Sentence 1
Before takeoff, she checked that the slaved gyro was aligned with the magnetic compass and that the slaving meter was centered.
Example Sentence 2
Before departure the pilot confirmed the slaved gyro matched the magnetic compass reading.