Attitude and heading instruments rely on which gyro characteristic?

• A. Precession
• B. Inertia
• C. Rigidity
• D. Nutation

Answer: (C)

Rigidity in space of a spinning gyroscope is what these instruments rely on. A fast-spinning rotor tends to keep its orientation in inertial space, resisting changes brought on by aircraft motion. When the airplane moves, external torques are applied through the gimbaled supports, causing the entire frame to react while the rotor’s axis stubbornly stays pointing in the same direction. That resistance makes the gimbals rotate relative to the gyro, and through the mechanism of precession, the instrument displays reflect the aircraft’s attitude or heading. Nutation and precession are related gyroscope behaviors, but the essential trait enabling attitude and heading indicators to provide a stable reference is rigidity in space.