Incident Overview
During an arrival after nightfall, the pilot of an aircraft was provided vectors for an Instrument Landing System (ILS) Runway 32 Approach to Arcata, California. The pilot was instructed to intercept the localizer at or above 6,000 feet and was subsequently cleared for the approach. Radar contact with the airplane was lost when it was approximately 22 miles from the airport.
Accident Sequence
The airplane crashed on mountainous terrain at an elevation of about 2,200 feet. Investigation of radar data revealed that the airplane was inbound on the ILS approach, positioned slightly left of the localizer centerline. After about one minute, the aircraft initiated a uniform left turn of approximately 30 degrees, followed immediately by an equally uniform right turn. The radius of the right turn began to decrease until the aircraft disappeared from radar after completing about 270 degrees of turn. The wreckage was found in proximity to the last radar return.
Wreckage Examination
Examination of the wreckage showed no evidence of preimpact mechanical failure. The airplane was destroyed during impact.
Pilot Background
According to a person who had flown with the pilot during practice of instrument flight procedures, the pilot occasionally turned the wrong way and, at times, gave the impression of having difficulty maintaining aircraft control.