What happened
During a return flight following a week of recurrent training, the pilot departed approximately 30 minutes later than the originally intended time. While the flight plan had been designed to stay west of certain mountainous terrain to avoid forecasted weather and ensure arrival before nightfall, the pilot instead chose a route east of the terrain. This decision placed the aircraft type in severe weather conditions after dark.
As the aircraft descended from its cruising altitude, it encountered turbulence that caused the autopilot to disengaged. Throughout the remainder of the flight, the pilot maintained communication with air traffic control (ATC) regarding altitude changes, course corrections, and the presence of icing. After being notified of icing reports from another aircraft, the pilot confirmed that moderate rime ice had accumulated on the airframe.
Following a descent to 7,200 ft msl, the aircraft's ground speed decreased from 124 kts to 84 kts. Despite instructions from ATC to climb back to 7,400 ft msl, the aircraft remained at 7,200 ft msl and initiated a right turn. Shortly after the pilot indicated they were turning, the aircraft entered a rapid descent. The aircraft struck hilly, wooded terrain near San Bernardino, resulting in the total destruction of the plane and one fatality.
Findings
- The pilot deviated from the pre-planned flight path intended to avoid hazardous terrain and weather.
- The aircraft encountered severe weather and moderate rime ice accumulation during the descent phase.