High Quality Content by WIKIPEDIA articles! The LN-3 Inertial Navigation System is an Inertial Navigation System that was developed in the 1960s by Litton Industries. The Lockheed F-104 Starfighter was the first supersonic fighter aircraft to be equipped with this Inertial Navigation System (INS). An inertial navigation system is a system which continually determines the position of a vehicle from measurements made entirely within the vehicle using sensitive instruments. These instruments are accelerometers which detect and measure vehicle accelerations, and gyroscopes which act to hold the accelerometers in proper orientation.