What defines the principle of rigidity in space for the Attitude Indicator?

The principle of rigidity in space refers to the behavior of a gyroscope, which is a key component of the attitude indicator. When the gyroscope is spinning, it maintains a fixed orientation relative to the stars and inertial space, regardless of the movement of its base—in this case, the aircraft. This characteristic allows the attitude indicator to accurately depict the aircraft's orientation in space by providing a stable reference for the pilot during maneuvers.

In the context of an airplane, as the aircraft turns, the gyroscope remains rigid in its position, allowing the attitude indicator to show whether the aircraft is in level flight, climbing, descending, or turning. This is critical for operations under Instrument Flight Rules (IFR) when visual references outside the cockpit may not be available. The correct answer reflects the fundamental operation of the attitude indicator as it pertains to the gyroscope’s ability to remain oriented despite the aircraft's movement.