CESSNA 310RMILLER AVIATION LLC

The pilot requested and was cleared for a non-precision instrument approach to the mountaintop airport that was obscured by clouds and fog; a precision approach to the same airport was also available. Review of the radar data revealed that the last two data points were aligned with the runway but below the published minimum descent altitude. Witnesses at a worksite 200 to 300 feet below the airport elevation heard the airplane approach and then saw it appear from beneath the clouds directly on top of, and parallel to, a ridgeline approximately in line with the final approach course. The witnesses heard and saw the airplane hit small branches in the treetops of some trees and then strike a large tree before disappearing from view. They each said that the sound of the airplane’s engines was smooth and continuous until contact with the trees. They stated that the fog was heavy and that the clouds were on top of the trees. The first identifiable tree strikes were 1,100 feet right of the runway centerline and about 100 feet below the airport elevation. The local director of public safety who responded to the airport immediately after the accident estimated that visibility was less than 30 feet due to fog. A postaccident examination of the wreckage revealed no preimpact mechanical anomalies. Toxicological testing of the pilot revealed use of nighttime cold medication at doses above therapeutic levels; such levels may have posed a hazard to flight safety.