THE DTSB
The DTSB determines the Probable Cause of this accident to be Pilot Error, in that the pilot chose to make a night flight, in the area of mountainous terrain, in IMC conditions, with a forecast freezing level at or near terrain elevation while enroute. It is suspected that the aircraft picked up in flight ice is such circumstance that prevented the aircraft from maintaining altitude. The aircraft was in a constant descent into the face of terrain, it is not likely that the pilot ever saw the terrain, or that he had any other option at that point. Of the four killer categories, this pilot hose to fly in four out of the four not recommended conditions.