Accident
The descent to Butte Airport began in poor weather conditions with zero visibility caused by fog. While the aircraft descended to an altitude of 6,060 feet, it struck trees and crashed on the slope of a mountain located a few miles from the airfield. At the time of the accident, the aircraft was flying at an insufficient altitude of 6,060 feet, while the minimum safe altitude was approximately 8,000 feet.
Aftermath
The wreckage was found two days later. All four occupants were killed.
Probable Cause
The official investigation determined the probable cause to be improper IFR operation on the part of the flying crew. The following factors were reported: no record of weather briefing received; weather forecast unknown or not reported; the aircraft hit a mountain at 6,060 feet approximately 1.6 nautical miles from the VOR; the published altitude was about 8,000 feet; mountains were obscured by fog; and the airport was below minimums.