Accident Sequence
The airplane broke apart in flight while the pilot was maneuvering at cruise altitude. Radar data indicated that the accident flight turned left, then began a descending right turn. The airplane broke apart during the turn.
Witness Observations
A witness in another airplane, who was 4 to 5 miles in trail of the accident flight at the same altitude, clearly saw the strobe lights of the accident airplane in front of him. The witness climbed to 9,500 feet and encountered cumulonimbus clouds and light icing. He stated that the temperature was 32-34 degrees Fahrenheit. He descended to 7,500 feet where he encountered severe turbulence, which caused him to hit his head violently against the cabin ceiling. He observed that he was below the accident airplane, and estimated that it was at 8,500 feet. He then lost sight of it.
Fracture Analysis
The fracture surfaces indicated a positive overload condition on all separated wing and tail components, with significant permanent set deformation of major structural elements in the wings and tail observed.
Toxicological Findings
A metabolite of diazepam (a prescription anti-anxiety medication commonly known by the trade name Valium) was found in the pilot's kidney and liver on toxicology testing. The pilot had a prior history of anxiety and depression that was treated with medication, though he had reportedly not received any recent medical treatment or medication. No blood or urine was available for analysis, so it is not possible to estimate when in the previous days or weeks that diazepam might have most recently been used or to determine the relevance, if any, of the medication or the condition for which it was used.