Furuno FAX 2084 weatherfax, Tokimec 110GS gyrocompass and Tokimec PR 2213 autopilot. A fibre optic gyrocompass is a compass and instrument of navigation. The tail vertical rudder meter set a vertical gyrocompass to control the vertical tail rudders. Prior to launch, the missile was referenced in azimuth by its gyrocompass inertial platform. Unlike a directional gyro or heading indicator, a gyrocompass seeks north. A "gyrocompass" is similar to a gyroscope. A gyrocompass, employed for navigation of seagoing vessels, finds the geometric north. Large ships typically rely on a gyrocompass, using the magnetic compass only as a backup. It use doppler sonar and a gyrocompass to navigate, and can operate to depth. The fibre optic gyrocompass is the first strapdown gyrocompass. A special gyrocompass built by Sperry Rand was installed shortly before the journey. Its navigation equipment included wireless direction finding, an echo sounding device and a gyrocompass. Her navigation equipment included wireless direction finding, and echo sounding device and a gyrocompass. This damaged the depth gauges, the gyrocompass, and the ice machine, besides causing leaks. A gyrocompass is subject to certain errors.