Accident Flight
A flight instructor, a commercial pilot receiving instruction, and a commercial pilot-rated passenger conducted an instructional flight in a multi-engine airplane under instrument meteorological conditions. After completing a practice instrument approach, the flight was cleared for a second approach. However, the landing runway was changed, and the controller vectored the airplane for an approach to the new runway. The pilot was instructed to turn to a southwesterly heading and maintain 1,600 ft until established on the localizer.
Radar Data and Control
Radar data showed that the airplane turned to a southwesterly heading on a course to intercept the localizer and remained at 1,600 ft for about 1 minute 39 seconds. It then began a descending right turn to 1,400 ft, continuing to 1,100 ft. At that point, the air traffic control controller issued a low altitude alert. Over the following 10 seconds, the airplane continued to descend at a rate exceeding 4,800 ft per minute (fpm). The controller issued a second low altitude alert, instructing the crew to climb to 1,600 ft immediately. About 5 seconds later, the pilot responded, "yeah I am sir, I am, I am." The airplane then climbed 1,400 ft over 13 seconds, resulting in a climb rate exceeding 6,700 fpm, followed by a descent to 1,400 ft over 5 seconds, resulting in a 1,500-fpm descent before radar contact was lost near the accident site.
Spatial Disorientation
Radar data following the initial instrument approach indicated that the airplane flew a relatively smooth and consistent flightpath with altitude and heading changes indicative of autopilot use until the final turn to intercept the localizer course. Maneuvering the airplane in restricted visibility placed the pilot in conditions conducive to developing spatial disorientation. The accident circumstances, including altitude and course deviations and the subsequent high-energy impact, are consistent with the known effects of spatial disorientation. Additionally, examination of the airframe, engines, and propellers revealed no preexisting anomalies that would have precluded normal operation. Therefore, it is likely that the pilot receiving instruction was experiencing spatial disorientation when the accident occurred.
Toxicological Findings
Toxicology testing of the flight instructor identified significant amounts of oxycodone and its active metabolite, oxymorphone, in liver tissue; oxycodone was also found in muscle. Oxycodone is an opioid pain medication available by prescription that may impair mental and/or physical ability required for performing potentially hazardous tasks. The flight instructor's tissue levels of oxycodone suggest that his blood level at the time of the accident was high enough to have had psychoactive effects. His failure to recognize and mitigate the pilot's spatial disorientation and impending loss of control further suggest that the flight instructor was impaired by oxycodone. Toxicology testing of all three pilots identified ethanol in body tissues; however, given the varying amounts and distribution, it is likely that the ethanol resulted from postmortem production rather than ingestion.
Probable Cause
The official probable cause is the pilot's loss of airplane control due to spatial disorientation during an instrument approach in instrument meteorological conditions, and the flight instructor's delayed remedial action. Contributing to the accident was the flight instructor's impairment from the use of prescription pain medication.