What happened
During an IFR flight, the crew completed a full weather briefing prior to departure. As they approached their destination, the pilots attempted to contact the airport via Unicom to request an advisory but received no reply. The aircraft landed on the runway under conditions of low visibility, with the runway lights being the primary visual reference.
Upon touchdown, the left main landing gear struck a snowbank or berm located on the left side of the cleared portion of the runway. This impact resulted in a loss of directional control. The aircraft subsequently drifted off the left side of the runway and came to a stop facing a reverse heading. At the time of the incident, the runway width was 100 feet, but the plowed area along the centerline had been reduced to approximately 45.5 feet.
Findings
Investigations revealed that no NOTAMs had been issued to alert pilots to the partially plowed state of the runway. Additionally, while the pilot-in-command had been informed during the pre-flight weather briefing that the runway surface contained thin, loose snow, the partially plowed condition of the runway contributed to the excursion when the gear contacted the unplowed edge.