Approach
The aircraft was conducting a full instrument landing system (ILS) approach to runway 18 at an airport located at an elevation of 6,445 feet in a mountainous area. The approach took place at night, and the control tower was closed. Due to the airport's location within a national park, the runway lights were not automatically illuminated during nighttime hours. The standard procedure for activating the runway lights during non-tower hours required the pilot to key the microphone multiple times on the Common Traffic Advisory Frequency (CTAF), which was the same as the tower frequency.
The copilot of the accident airplane made several attempts to turn on the runway lights by keying the microphone on the UNICOM frequency. However, that frequency had been the CTAF until approximately six months before the accident. The captain continued the descent below approach minimums despite the runway lights not being illuminated.
Landing
During the landing flare, the captain reported that strong crosswinds and blowing snow created a white-out condition. The aircraft touched down 195 feet left of the runway centerline, in snow-covered terrain located between the runway and the taxiway.
Aftermath
All four occupants escaped without injury. Among them were actress Sandra Bullock and musician Bob Schneider. Two ILS Runway 18 approach plates were found inside the aircraft. One was outdated and listed the UNICOM frequency as the CTAF; the other was current and correctly showed the tower frequency as the CTAF.