Accident Details
During arrival, the pilot was advised that the destination weather was estimated 500 feet overcast, visibility one mile with fog, and the airport was below minimums. The pilot elected to make an NDB runway 23 approach, stating he would divert if a missed approach was made. He was provided radar vectors and cleared for the approach. At the initial approach fix (IAF/Tiney intersection), radar service was terminated and the pilot was instructed to contact the tower. The tower again reminded the pilot that the airport was below minimums.
Approximately two minutes later, the pilot reported over the outer marker (OM), which was 4.2 miles past (southwest of) the NDB/final approach fix (FAF) and 3.9 miles northeast of the airport. Seconds later, the tower transmitted information (just recorded from ARTCC) that the aircraft was 2.5 miles east of course. The tower attempted to notify the pilot, but radio and radar contact were lost.
Investigations revealed that the aircraft impacted a ridge nearly 4 miles past the NDB and two miles left of course at an elevation of approximately 1,900 feet, before passing the OM. The minimum descent altitude (MDA) between the NDB and OM was 2,220 feet msl, and the MDA after passing the OM was 1,940 feet; airport elevation was 1,161 feet.
Investigation Findings
No preimpact aircraft problems were found. The NDB facility operated satisfactorily during flight and ground checks. All five occupants were killed.
Probable Cause
The official probable cause was the pilot's improper in-flight planning/decision and improper IFR procedure, failure to maintain proper alignment and altitude, in dark night conditions with low ceiling, fog, and below-minimums weather, resulting in collision with mountainous/rising terrain.