What happened
During an instrument approach using LOC/DME procedures, an aircraft struck mountainous terrain located roughly 10.5 dme from the airfield. At the time of the impact, the aircraft was in a landing configuration. The flight was attempting to descend to a minimum altitude of 9,500 feet, which was the required level until reaching the final approach fix situated at 9.3 dme. However, the aircraft struck the terrain before reaching this point.
All six fatalities occurred during the accident. Investigation of the wreckage revealed that the elevator trim jackscrew was positioned at approximately 18 degrees in a nose-up orientation. Additionally, the altitude preselect, which was integrated with the Sperry autopilot system, had been set to 9,500 feet.
Findings
Investigators recovered twenty-four different prescription and nonprescription medications from the cabin. A toxicology analysis of the pilot's liver fluid revealed the presence of chlorpheniramine, an antihistamine, at a concentration of 0.206 (ug/ml, ug/g). According to medical assessments from an FAA flight surgeon, this level corresponds to roughly 0.034 ug/ml in the blood, which falls within the therapeutic range of 0.01 to 0.04 ug/ml.
Despite being within therapeutic limits, the presence of chlorpheniramine is a significant factor because the medication is contraindicated for flight due to its potential to cause drowsiness. This specific drug is a known component of Comtrex, one of the medications found on the aircraft.