What happened
While performing an IFR arrival, the aircraft was following vectors for an ILS runway 16L approach. The flight was operating at 3,000 feet on a heading of 270 degrees, approximately 8 miles north of the final approach fix. Air traffic control instructed the pilot to execute a left turn to a heading of 185 degrees and descend to 2,200 feet, with instructions to maintain that altitude until established on the localizer. Although the pilot acknowledged these instructions, radar and radio contact were lost approximately one minute later.
Observers near the crash site witnessed the aircraft descending through the cloud base. These witnesses described the aircraft as being in a steep left bank with a nose-down attitude, noting that the engines appeared to be revving. The aircraft impacted the ground seconds after this visual sighting. No smoke or fire was observed prior to the impact, and the pilot had not communicated any mechanical difficulties to the tower controller.
Findings
Post-accident examination of the airframe revealed no evidence of mechanical failure. However, toxicological analysis of the pilot's liver and kidney fluids revealed the presence of chlorpheniramine, a sedating antihistamine, at levels of 0.323 mcg/ml in the liver and 0.073 mcg/ml in the kidney. Additionally, traces of dextromethorphan, pseudoephedrine, and phenylpropanolamine—all components of common over-the-counter cold medications—were detected in the pilot's system.