Abstract: An air training evaluation process which corrects the position and velocity sensed by an aircraft's inertial navigation system (INS) to obtain more accurate data on the aircraft's position during an engagement.In carrying out the process the aircraft's on-board INS system is employed to obtain pre-flight data on position and velocity, data on position and velocity during the engagement, and post-flight data on position and velocity. The pre-flight data on position and velocity and the post-flight data on position and velocity are compared with independently determined data on the pre-flight position and velocity of the aircraft and with independently determined data on the post-flight position and velocity of the aircraft respectively to obtain pre-flight error functions and post-flight error functions on position and velocity.