Accident Overview
An airplane collided with mountainous terrain approximately 11.3 nautical miles south-southeast of the departure airport. The accident site elevation was about 10,300 feet mean sea level (msl). The airplane approached the site on a heading of approximately 240 degrees, which placed it on the lee side of a high ridgeline with winds exceeding 50 knots. A valley extending southwest directly in front of and 90 degrees to the ridgeline may have produced a funneling effect, significantly accelerating the wind flow over the ridge.
Weather Conditions
The departure airport's automated weather observation system reported clear skies up to 12,000 feet above ground level (agl), with winds from 220 degrees at 14 knots gusting to 26 knots at the estimated time of departure. The pilot obtained a weather briefing 1 hour and 46 minutes prior to departure. The briefing indicated that winds at 9,000 feet msl over the area were from 210 degrees at 50 knots, and that conditions would worsen by 1100. The briefing also included AIRMETS for mountain obscuration, moderate turbulence, and moderate rime and mixed icing above the freezing level.
Satellite imagery of the accident site at the time of the event showed high clouds above the mountains, with cloud tops estimated at 13,000 feet. Rotor clouds were observed southwest of the crash site. Studies have documented that severe turbulence, wind shear, and downdrafts are commonly present on the downwind side of high mountainous terrain when high wind conditions exist.
Aircraft Performance
The maximum climb rate for the airplane at 9,000 feet under static conditions was calculated to be 900 feet per minute.
Examination
No preimpact mechanical malfunctions were discovered during examination of the wreckage.