What happened
According to the pilot, the flight proceeded normally until the approach phase. During descent, both the pilot and the co-pilot were late in applying all of the aircraft's anti-icing devices. As a result, the aircraft's windshield iced over, limiting visibility to only a small amount.
Upon touchdown, the reversers were deployed. The pilot had received information prior to landing that braking action was poor and that the runway was icy, although it had been sanded. The pilot landed on the left side of the runway centerline. Shortly after touchdown, the aircraft began to drift further to the left. The left main gear left the runway, causing the aircraft to be pulled off the pavement. The aircraft departed the runway entirely and came to rest approximately 3000 feet from the touchdown point.
Findings
Contributing factors included the late application of anti-icing systems, windshield icing that limited visibility, poor braking action on an icy and sanded runway, and landing left of centerline which led to loss of directional control.