Definition
The heading reading shown on the magnetic compass at any given moment. Because the magnetic compass is affected by the Earth's magnetic field, by the aircraft's acceleration and deceleration, and by banking during turns, the compass indication is not always the same as the aircraft's actual magnetic heading, particularly during turns onto northerly or southerly headings.
Plain English
What the magnetic compass is currently showing. It is not always the true heading, because the compass lags, leads, or swings during turns and speed changes.
Context Anchor
Used during compass turns, especially when deciding when to start rolling out of a turn to end on the desired heading.
Derivation
Compass comes from older words meaning to measure or mark out a circle, which fits its use as a direction instrument. Indication comes from a word meaning to point out. Together, the phrase means the direction the compass is pointing out or displaying.
Why Pilots Care
Misreading compass indications during turns leads to heading errors and potential loss of situational awareness.
Intuition Check
Do not assume compass indication means the airplane’s exact true direction at every instant. Here it means the heading shown by the compass, which can be temporarily misleading during turns or speed changes.
Example Sentence 1
When rolling out of a turn to a northerly heading, the pilot stopped the turn before the compass indication reached north, allowing for the lag.
Example Sentence 2
In a standard-rate turn through north, the compass indication lags and must be read with lead or lag in mind.