Witness Observations
Two witnesses reported seeing the airplane pitch up and enter a steep left turn, followed by a roll and a descending spiral. The aircraft then reappeared from behind a mountain ridge, executed another tight left turn, rolled over, and disappeared behind the mountain again. The witnesses noted that despite the airplane being in close proximity to 'black thunderstorm clouds' to the north, it was in an area 'free of clouds.' They heard no thunder and saw no lightning.
Weather Conditions
WSR-88D Doppler weather radar detected 'weak weather echoes' in the vicinity of the accident site between 1413:52 and 1418:54. These echoes were moving from northwest to southeast with maximum tops near 33,000 feet. Satellite photos showed cloud cover in the area of the accident site and very cold radiative temperatures (high cloud tops) of about 29,000 feet.
Impact and Wreckage
The airplane struck a large rock head-on at the 8,166-foot level in mountainous terrain. All of the airplane was accounted for. A 15-inch blade stub was all that remained of the propeller assembly; it was twisted, curled, and bore leading edge gouges and chordwise scratches on the cambered surface.