heading indicator

The heading indicator (Directional Gyro or DG) is an instrument used in an aircraft to inform the pilot of his heading. It is sometimes referred to by its older name, the directional gyro, or (UK usage) direction indicator or DI. The primary means of establishing heading in most small aircraft is the magnetic compass, but that suffers from errors created by the 'dip' or downward slope of the earth's magnetic field. Dip error causes the magnetic compass to read incorrectly whenever the aircraft is in a bank, or during acceleration, making it difficult to use in any flight condition other than perfectly straight and level. To remedy this, the pilot will typically maneuver the airplane with reference to the heading indicator, as the gyroscopic heading indicator is unaffected by dip and acceleration errors. The pilot will periodically reset the HI to the heading shown on the magnetic compass.
See more at Wikipedia.org...

An instrument which displays heading transmitted electrically from a remote compass system. 1/11/80

Instrument qui indique le cap, transmis par signal électrique, depuis une centrale de cap située à distance. 1/11/80