Definition
Two primary flight instruments often driven by the aircraft's vacuum or pneumatic system. The attitude indicator displays the aircraft's pitch and bank relative to the horizon, and the heading indicator displays the aircraft's magnetic heading. In many general aviation aircraft, both contain gyroscopes spun by air drawn through the instruments by an engine-driven vacuum pump.
Plain English
These are the two cockpit instruments that show which way the airplane is pointed -- one shows whether the nose is up, down, or banked, and the other shows the compass direction the airplane is flying. In many planes, both are powered by suction from a pump on the engine.
Context Anchor
Seen in instrument flying and aircraft system malfunction discussions, especially when checking what instruments may be affected by a vacuum or pressure system failure.
Derivation
Attitude comes from a word meaning posture or position. In aviation, it means the airplane’s position in the air, not a person’s mood. Heading comes from the idea of the direction the head or front of something points. Indicator means something that points out or shows information.
Why Pilots Care
Failure of these instruments in instrument meteorological conditions forces immediate use of partial-panel techniques to maintain aircraft control.
Grounding Statement
If the air-powered system fails, the airplane may still be flying normally while these instruments slowly drift, freeze, or show the wrong information.
Intuition Check
Do not read attitude as emotional attitude here. In this term, attitude means the airplane’s physical position relative to the horizon: nose up or down, wings level or banked.
Example Sentence 1
When the vacuum pump failed, both the attitude and heading indicators began to drift, so the pilot transitioned to partial-panel flying using the turn coordinator and magnetic compass.
Example Sentence 2
The pilot cross-checked the turn coordinator and altimeter after losing the attitude and heading indicators.