NTSB Probable Cause

THE PILOT'S FAILURE TO MAINTAIN AIRCRAFT CONTROL DUE TO SPATIAL DISORIENTATION. FACTORS IN THIS ACCIDENT WERE: 1) THE PILOT'S FAILURE TO OBTAIN A PREFLIGHT WEATHER BRIEFING AND TO PROPERLY EVALUATE THE EXISTING WEATHER CONDITIONS PRIOR TO FLIGHT, AND 2) REPORTED UNFAVORABLE WEATHER CONDITIONS, INCLUDING TURBULENCE, SNOW, RAIN, AND OBSCURATION AT FLIGHT ALTITUDES ALONG THE PILOT'S ROUTE OF FLIGHT.