Approach and Weather Conditions
The flight was initially planned as a night visual approach. As weather deteriorated, the pilot received vectors for an Instrument Landing System (ILS) approach to runway 8 and was cleared for the approach at 0511 Central Daylight Time. While on final approach, the pilot observed that both ILS receivers provided erratic localizer and glideslope information, though the instruments were functional. The localizer course deviation indications did not correspond with the Automatic Direction Finder (ADF) readings. Despite these discrepancies, the pilot continued the approach.
At 0512, another flight landing on runway 14L reported breaking out of clouds at minimum descent altitude (200 feet above ground level). One minute later, the pilot was advised of the latest weather: a 200-foot broken ceiling and 3 miles visibility.
ILS Configuration Issue
The airport was equipped with ILS systems for runways 8 and 26, each with different identifiers. However, both systems used the same transmitter and frequency for the localizer signal. Investigation revealed evidence that the transmitter was set to provide the localizer signal for runway 26 rather than runway 8. The pilot did not identify the signal. A flight check later determined that the ILS would have produced a usable signal in that configuration, but it would have provided back course (reverse) localizer sensing commands.
The tower controller believed the ILS was configured for runway 8 but could not recall changing it from the previous setting for runway 26. The Automatic Terminal Information Service (ATIS) had not been updated since 0011 CDT. At 0529, the weather was reported as 100 feet overcast, 3/4 mile visibility with fog; the tower reported 1/4 mile visibility. The Air Traffic Control Tower supervisor was not in the tower cab at the time.
Accident
While the pilot was interpreting the instruments, the aircraft broke out of clouds and struck trees approximately 3/4 mile left of the intended course. The aircraft then crashed and caught fire.