Sequence of Events
During arrival for an ILS-2 approach to Runway 11, the pilot was advised to hold at the KONA NDB while snowplows finished clearing the runway. At that time, weather conditions at Missoula were reported as 1,200 feet obscured, 2 miles visibility with light snow and fog. Temperature and dew point were 32°F and 30°F, respectively.
Approximately one minute after reaching the KONA NDB, the pilot declared an emergency and reported that both engines were beginning to lose power. In response, the pilot was cleared for an immediate approach. Subsequently, the aircraft collided with trees and crashed in an area between the KONA NDB and the ILS outer marker.
Investigation Findings
During the investigation, all fuel tanks were found ruptured, but fuel stains were observed adjacent to both tip tanks. No preimpact mechanical failures were identified. Examination revealed that both alternate air handles were found in the closed position.
Witnesses reported hearing the aircraft at low altitude just prior to the crash. They stated that one or more engines were running and that heavy snow was falling and blowing at the time.