NTSB Probable Cause

THE PILOT'S FAILURE TO MAINTAIN ADEQUATE TERRAIN CLEARANCE WHILE MANEUVERING TO LAND DURING AN INSTRUMENT APPROACH. FACTORS RELATED TO THE ACCIDENT WERE: THE PILOT'S FAILURE TO OBTAIN A WEATHER BRIEFING PRIOR TO DEPARTURE, HIS DELAYED DECISION TO MAKE AN EMERGECY LANDING AFTER ENCOUNTERING ICING CONDITIONS EN ROUTE, ICE ACCUMULATION ON THE AIRPLANE, AND THE DARK NIGHT.