Lost at 15:00 hours in the northern part of the Utah Test and Training Range, about 65 miles west of Hill AFB. The mishap occurred when the aircraft was performing basic fighter manoeuvres. Bad weather slowed search efforts, but is most likely not a factor as it would have been above the weather. The pilot, Major Gregory C. Martineac, did not eject, and was killed. The aircraft was found laying in four feet of mud. Crash probably caused by G-induced loss of consiousness.