Incident Summary
The accident occurred after the pilot departed Front Range Airport at approximately 2008 local time. The pilot climbed to an altitude of 7,000 feet mean sea level, accelerated to 270 knots, and requested an IFR clearance from air traffic control. During the flight, the pilot made several changes in airspeed and climb rate until radar indicated an unusually high descent rate of 8,500 feet per minute. The pilot reported to ATC that he had stalled the airplane. Shortly after, radar showed the aircraft climbing at 7,500 feet per minute until its estimated airspeed dropped to 10 knots, then it began another descent at 8,400 feet per minute, ending when the airplane impacted the frozen ground.
Weather and Conditions
At the time of departure, the weather at Front Range Airport (elevation 5,512 feet) featured an overcast ceiling at 500 feet. Witnesses reported that the tops of the thin cloud layer were at 8,500 feet mean sea level, and conditions above the clouds were described as very dark, with no stars or moon visible.
Pilot Experience and Workload
The pilot had flown a total of four flights for seven hours in the 40 days preceding the accident. Five airline pilots, each with 3,000 to 5,000 hours of experience in Swearingen aircraft, independently stated that although the accident airplane was certified for single-pilot operation, they believed it was essentially a two-pilot airplane due to the high workload involved.
Probable Cause
The official probable cause was determined to be the pilot inadvertently stalling the airplane and his subsequent spatial disorientation, which prevented him from maintaining aircraft control. Factors contributing to the accident were excessive workload on the pilot and the dark night light conditions.