What must be done to use the stored heading alignment mode in the inertial reference system?

To use the stored heading alignment mode in the inertial reference system, gyrocompass (GC) alignment is required. This process involves aligning the inertial navigation system to true north based on the aircraft's heading and position information. Gyrocompass alignment allows the inertial reference system to accurately reference the aircraft's orientation in space.

This alignment technique uses the principles of gyroscopic precession to maintain orientation, enabling the system to stabilize and provide reliable heading data once the aircraft is in motion. The gyrocompass operates independently of the earth's magnetic field, which is particularly beneficial in environments where magnetic influences may cause discrepancies.

The other alignment methods—such as in-flight alignment, BATH alignment, and attitude alignment—serve different purposes or are specific to different operational contexts within the inertial reference system and do not directly facilitate the stored heading alignment mode in the way that gyrocompass alignment does.