Definition
A flight instrument that displays aircraft heading using a spinning gyroscope rather than magnetic sensing. Because the gyro's spin axis remains fixed in space, the instrument provides a stable, steady heading reference that is unaffected by the turning, pitching, banking, and acceleration errors that disturb a magnetic compass. It must be periodically aligned with the magnetic compass during straight-and-level, unaccelerated flight, since it has no inherent sense of north and will slowly drift over time.
Plain English
A heading instrument driven by a spinning wheel inside it. The spinning wheel holds steady in space, so the heading reading stays smooth and accurate during turns and bumps, unlike the magnetic compass which jumps around. The pilot resets it against the compass every so often.
Context Anchor
Seen when pilots compare the magnetic compass with the heading instrument, especially in discussions of compass errors such as oscillation error.
Derivation
Gyroscopic comes from the Greek 'gyros' (a circle or turn) and 'skopein' (to look at) — literally 'a thing that watches the turning.' A gyroscope is a spinning wheel whose axis resists being tipped. That resistance is what gives this instrument its steady, drift-free heading reading.
Why Pilots Care
It supplies a stable heading reference that is not affected by the turning and acceleration errors that disturb the magnetic compass.
Intuition Check
Heading does not mean the route you intend to fly here. It means the direction the aircraft’s nose is pointed at that moment. Gyroscopic does not mean magnetic. The instrument uses a spinning mechanism for steadiness, and the compass is used to set or check it.
Example Sentence 1
After completing the turn, the pilot cross-checked the gyroscopic heading indicator against the magnetic compass and reset it during the next stretch of straight-and-level flight.
Example Sentence 2
During the turn the gyroscopic heading indicator continued to show smooth heading changes without the side-to-side swing of the compass.