Flight History
An instrument-rated pilot was conducting a cross-country flight. According to air traffic control records, a controller provided the pilot with vectors to an intersection for a GPS approach. Federal Aviation Administration radar data indicated that the airplane deviated from the assigned intersection by 6 nautical miles and descended 800 feet below its assigned altitude before correcting toward the initial approach fix. Subsequently, the aircraft crossed the final approach fix 400 feet below the minimum crossing altitude and continued to the minimum descent altitude, where the pilot initiated a missed approach.
The missed approach procedure required a climbing right turn to 2,500 feet mean sea level (msl) while navigating southwest back to the intersection. However, radar data showed the airplane flying southeast, with multiple ascents and descents before leveling at 2,800 feet msl. The airplane then entered a right 360-degree turn and nearly completed another circle before descending into terrain.
Weather Conditions
The recorded weather at the destination airport around the time of the accident included a cloud ceiling of 400 feet above ground level and visibility of 3 miles. The pilot reported to an air traffic controller that adverse weather was causing the airplane to lose "tremendous" amounts of altitude. However, weather radar did not indicate any convective activity or heavy rain at the airplane's location.
Pilot Experience and Equipment
On his most recent medical application, the pilot reported over 4,000 total flight hours. The investigation could not corroborate those reported hours or document any recent or overall actual instrument experience. Additionally, it could not be determined whether the pilot had experience using the onboard GPS system, which had been installed approximately six months before the accident. The accident flight track is indicative of the pilot not using the GPS effectively, possibly due to a lack of proficiency or familiarity with the equipment.
Investigation Findings
Examination of the wreckage revealed no evidence of any preimpact mechanical malfunctions or failures. Toxicological tests detected ethanol and other volatiles in the pilot's muscle, consistent with postmortem production. The restricted visibility and precipitation, combined with maneuvering during the missed approach, would have been conducive to the development of spatial disorientation. The variable flightpath off the intended course was consistent with loss of airplane control due to spatial disorientation.