The gyromagnetic compass is the combination of a simple compass and a gyroscope. The indications of the magnetic compass are stabilized by the gyroscope to reduce the effects of acceleration and turning errors. The main components of a gyromagnetic compass are the flux valve, the heading indicator, the slaving amplifier, the synchronizing motor, and the horizontal gyro.

The flux valve (=flux detection unit) senses the Earth’s magnetic field which is compared to the position of the drive shaft connecting the horizontal gyro and the heading indicator. Anytime the gyro has drifted, and its position would differ from the flux valve field, an AC error signal is transmitted to the precession amplifier. Before being converted into a DC signal, the AC signal is first amplified, and phase detected. This signal drives the precession motor that will realign the gyro. The new position is compared again, and the synchronization will continue until the heading indicator is synchronized. The flux valve is usually remotely located in the wingtip or the fin of the aircraft to be free of any magnetic disturbances.

An easy way to remember the order of the gyromagnetic compass operation is by using the acronym ‘FEAT’: