Approach Attempts
The pilot attempted to intercept an instrument landing system localizer three times without success. During the attempts, the pilot informed Air Traffic Approach Control that he was experiencing difficulty performing a "coupled" approach and that he was trying to "get control" of the airplane. Radar and voice data review indicated that the pilot was able to turn to headings and climb to altitudes when directed by air traffic control during these three approaches.
Final Descent and Crash
The airplane disappeared from radar after the third approach attempt. It subsequently impacted a field and then a barn. The aircraft came to rest in an upright position, and a post-crash fire ensued.
Toxicology Findings
Postmortem toxicology results were consistent with the regular use of a prescription antidepressant and the recent use of a larger-than-maximal dose of an over-the-counter antihistamine known to cause impairment.
Aircraft Examination
Examinations of the airframe and engine revealed no preimpact anomalies that would have prevented normal operation.