Accident Description
The accident occurred during a night VOR/DME approach conducted in instrument meteorological conditions. The airplane was outfitted with VOR, LORAN, and RNAV navigation receivers. The published approach procedure specified step-down fixes: at 13 DME the minimum altitude was 1,800 feet; at 10 DME the minimum altitude was 1,040 feet. The missed approach point was located at 6 DME, and the VOR/DME transmitter was situated 5.5 miles beyond the airport.
Radar data revealed that the pilot's descent was governed by distances from the approach end of the runway rather than by DME from the VOR. When the airplane was 13.52 miles from the VOR (7.58 miles from the runway end), it had descended to 1,000 feet—well below the required 1,800 feet at 13 DME. Subsequently, the airplane impacted rising terrain at an altitude of approximately 900 feet, about 11.5 miles from the VOR and 5.5 miles from the runway end. The impact and ensuing post-crash fire precluded a functional check of the radio equipment.
Pilot Qualifications
Federal Aviation Regulations (FAR) Part 135 required a pilot-in-command to have at least 1,200 hours of total flight time. The investigation documented the pilot's total time as approximately 1,057 hours, which fell short of that requirement.
Probable Cause
The official probable cause determined by the investigation was the pilot's failure to follow the published instrument approach procedure and his descent below the minimum descent altitude. Contributing factors included the night conditions, low ceilings, and fog.