Definition
A small adjustment device in a remote indicating compass system that uses two sets of corrective magnets, controlled by N-S and E-W adjusting screws, to cancel out magnetic deviation errors caused by the aircraft's own electrical and metallic components. It is mounted near the flux valve (the compass system's magnetic sensor) and is set during a compass swing to bring heading errors within acceptable limits on each cardinal heading.
Plain English
A small device with adjustment screws that fine-tunes the compass system to cancel out magnetic interference from the aircraft itself, so the heading shown is accurate.
Context Anchor
Seen in remote indicating compass discussions, especially when the compass system is being checked, adjusted, or troubleshot.
Derivation
From Latin compensare, 'to weigh together' or 'balance out.' The unit literally balances out unwanted magnetic influences in the aircraft so the compass reads true.
Why Pilots Care
Without proper compensation the heading indicator will show incorrect directions, leading to navigation errors especially in instrument conditions.
Analogy
It is like zeroing a scale before weighing something. The scale may work, but if it starts with an offset, every reading will be wrong until that offset is corrected.
Intuition Check
A compensator unit is not the compass sensor and it is not a backup compass. It is an adjustment part that helps remove error from the remote compass indication.
Example Sentence 1
After avionics work near the tail, the technician performed a compass swing and adjusted the compensator unit to bring the heading errors within tolerance.
Example Sentence 2
During the compass swing procedure the pilot rotated the aircraft while adjusting the compensator unit to reduce deviation errors.