What was found
AFTER TAKEOFF FROM RKSI, DURING CLIMB, ALL THREE INERTIAL NAVIGATION SYSTEMS INS 1, INS 2, AND INS 3 FAILED AND CREW WAS UNABLE TO NAVIGATE FLIGHT PLAN WAYPOINTS THROUGH REST OF INTENDED FLIGHT. CREW TERMINATED FLIGHT, DUMPED 160,000 POUNDS OF FUEL, RETURNED TO RKSI AND LANDED SAFELY AT RKSI. UPON LANDING MAINTENANCE CREW TROUBLESHOT SYSTEM, SECURED AND REALIGNED ALL THREE NAVIGATION UNITS, INU 1, INU 2, AND INU 3, IN ACCORDANCE WITH BOEING 747 AMM 34-41-03 AND 34-41-00 CONFIGURATION 2, ALL OPERATIONS NORMAL THEREAFTER.