Definition
An instrument indication error in a magnetic compass or directional gyro caused by the pilot turning the aircraft in the wrong direction in response to a misread heading, or by the instrument itself displaying a heading change opposite to the actual turn. In a magnetic compass, this is most commonly seen during turns through northerly or southerly headings where the compass card briefly indicates a turn in the reverse direction.
Plain English
A mistake where the heading instrument shows the aircraft turning the opposite way to how it is actually turning, or where the pilot reacts to that wrong indication and turns the wrong way.
Context Anchor
Most often encountered during post-maintenance inspections, preflight control checks, and any check that confirms the controls move freely and in the correct direction.
Derivation
"Reversal" comes from the Latin reversus, meaning "turned back." Here it captures the idea that the indicated direction of change is turned back — opposite — to the real direction of change.
Why Pilots Care
Unrecognized control reversal can produce sudden, opposite roll response and loss of control above critical speeds.
Analogy
It is like turning a car’s steering wheel left and having the front wheels turn right. The control still moves, but it gives the opposite result.
Intuition Check
Do not confuse this with a control that is stuck or hard to move. In a control reversal error, the control may move smoothly, but it moves the airplane’s control surface the wrong way.
Example Sentence 1
The student made a control reversal error during a timed turn to north, banking left when the compass momentarily showed the heading increasing.
Example Sentence 2
The flight manual cautioned against aggressive roll inputs once control reversal error became possible.