Flight Details
The pilot filed an instrument flight rules (IFR) flight plan from the departure airport. The estimated time en route was 2 hours 47 minutes, with a planned cruising altitude of 12,000 ft mean sea level (msl). The flight planning application provided weather briefing information, including a convective SIGMET active for the time and route of flight, as well as pilot weather reports (PIREPs) for turbulence and moderate chop. However, it could not be determined whether the pilot reviewed this information.
The flight departed approximately 45 minutes after the filed departure time. About 1 minute after departure, the pilot contacted air traffic control (ATC) to obtain an IFR clearance. The controller cleared the pilot to the destination as filed, issued a climb to 10,000 ft msl, and provided a weather advisory for moderate and heavy precipitation along the route, which the pilot acknowledged.
Accident Sequence
Approximately 4 minutes later, the controller issued a climb to 12,000 ft msl, which the pilot acknowledged. Around that time, the controller began a position relief briefing with a relieving controller, which took about 2 minutes. About 2 minutes after that, the new controller queried the pilot after observing that the flight had deviated left of course.
Flight track data showed that, just before the query, the airplane deviated from its southwesterly ground track and began a 45-second, right 270° turn starting at an altitude of 9,800 ft msl. During the turn, the airplane descended to 8,700 ft msl before climbing back to 9,800 ft msl when it rolled out on an easterly ground track.
About 1 minute after the controller's query, the pilot responded, stating he had “lost” something, followed by a similar transmission 27 seconds later. This was the last transmission attributed to the accident airplane. The airplane continued on a wavering east track for about 40 seconds, descending back to 8,700 ft msl before climbing to 9,025 ft msl, after which it entered a tight, right, descending spiral until track data was lost.
The airplane crashed in a dense wooded area in Trout Creek and was totally destroyed. All five occupants were killed.
Probable Cause
The official probable cause was the pilot’s loss of airplane control in flight due to spatial disorientation during a climb to cruise altitude in instrument meteorological conditions and turbulence, which resulted in the in-flight breakup of the airplane. Contributing to the accident was the pilot’s continued flight into an area of known convective activity.