Flight and Weather Briefing
Prior to the instrument flight rules (IFR) flight, the pilots obtained a complete weather briefing. During the briefing, the pilot-in-command was advised of thin, loose snow on the runway, as noted by the second officer, a commercial pilot.
Landing and Accident Sequence
Upon arrival at the destination, the pilots attempted to obtain an airport advisory on Unicom but received no response. They landed on the runway in low visibility, with the runway lights visible. After touchdown, the left main landing gear contacted a berm or snowbank located on the left side of the plowed area. The pilots were unable to maintain directional control, and the aircraft drifted off the left side of the runway, coming to rest on a reverse heading.
Runway Condition
The runway, which was 100 feet in width, had been plowed to approximately 45.5 feet width along the centerline. No NOTAMs had been filed regarding the partially plowed condition of the runway.
Probable Cause and Factors
The probable cause of the accident was the failure of airport personnel to properly remove snow from the runway or issue an appropriate NOTAM concerning the runway condition. Factors relating to the accident were the low light condition at dawn and the snowbank or berm that was left on the runway.