On a later X-15 flight, he was awarded a Distinguished Flying Cross for successfully landing a North American X-15 after its nose wheel extended while flying at nearly Mach 5. He made his final X-15 flight on July 1, 1966, then returned to regular Air Force duties. He attended F-4 Phantom II Combat Crew Training, went through survival training, and in March 1968 he was sent to Cam Ranh Bay Air Base, Republic of Vietnam, where he was Assistant Deputy Commander for Operations with the 12th Tactical Fighter Wing and flew 189 combat missions.