Gyroscopic Instruments

Three instruments use spinning gyroscopes and rely on two physical properties: rigidity in space, which keeps a spinning gyro pointed the same way, and precession, a delayed reaction to an applied force. The attitude indicator shows pitch and bank against an artificial horizon and is the primary reference for aircraft attitude. The heading indicator displays heading but slowly drifts from precession, so it must be reset to the magnetic compass periodically, usually about every fifteen minutes. The turn coordinator shows the rate of turn and, through the inclinometer ball, whether the turn is coordinated or slipping and skidding. Power sources matter: in many trainers the attitude and heading indicators are driven by an engine vacuum pump while the turn coordinator is electric. That split is deliberate, because if the vacuum system fails the pilot still has an electrically driven turn instrument to help maintain control.