Incident
A 14 CFR Part 135 cargo flight impacted terrain during a circling approach at Sioux Falls. The pilot had reported picking up ice en route, and the aircraft experienced a loss of control during the final phase of the approach. A post-crash fire ensued.
Flight and Weather Briefing
During a weather briefing, the pilot was informed that conditions at the destination airport included "two miles light freezing drizzle and fog eight hundred overcast" with a forecast of "one mile variable four miles light freezing drizzle and fog five hundred overcast" until midnight. The briefer asked the pilot if he still intended to proceed, and the pilot responded, "Ya I guess they said I have to."
Pilot Reports
The pilot reported beginning to accumulate ice approximately 50 miles from the destination, with increasing accumulation as the flight progressed. The pilot informed ATC of significant icing, and ATC issued the VOR Runway 15 approach. When asked whether he wanted to fly a straight-in approach or circle to land on Runway 3, the pilot chose to circle. While circling, the aircraft began to "shutter." The pilot stated that the de-ice boots had become ineffective. He applied full power, but the aircraft continued to shutter at zero degrees bank. The pilot reported, "It became apparent I could not make the runway at this point. I had to lower the nose to keep the aircraft from stalling. At approximately 50 feet I lowered the landing gear and crashed straight ahead into a highway department equipment storage yard."
Aftermath
A post-crash fire occurred. The pilot had previously voiced concerns about the weather to company dispatch and requested to fly to an alternate airport, but was directed to proceed to Sioux Falls.