What happened
The pilot was executing an instrument landing system (ILS) approach to runway 18 under actual instrument meteorological conditions. Shortly after reporting the passage of the outer marker, the aircraft departed from the localizer centerline, drifting to the left. At a position approximately one-half mile outside the middle marker and about one-quarter mile left of the intended path, the aircraft descended into a wooded area while maintaining an easterly heading.
The impact with the trees occurred while the aircraft was in a slightly left bank and slightly nose-low attitude, after which it struck the terrain. The resulting post-impact fire destroyed all pilot and aircraft records, preventing further review of flight logs or maintenance history.
The investigation
Examination of the aircraft engine following the accident revealed no evidence of pre-impact malfunction or failure. A subsequent inspection of the aircraft's instruments also disclosed no malfunctions that could have contributed to the accident. Additionally, a flight check of the ILS runway 18 system performed the day after the incident indicated that the navigation aid was functioning normally.
The pilot had obtained an instrument rating on January 3, 1987. However, the pilot's total instrument flying experience could not be determined due to the destruction of records. The pilot remained in contact with air traffic control prior to the impact and did not report any problems with the aircraft or navigation systems.
Findings
The deviation from the localizer centerline during the approach appears to be the primary factor leading to the loss of controlled flight. With engine and instrument malfunctions ruled out, and the ILS system confirmed operational, the cause remains linked to the pilot's ability to maintain lateral guidance in instrument conditions.