Accident Overview
Witnesses reported seeing the accident airplane spinning in a nose-down, near-vertical attitude before it collided with the ground. The accident site was located approximately 3 miles from the approach end of the intended runway. The pilot was conducting an instrument landing system (ILS) approach at the time of the accident.
Flight Data Analysis
A review of radar data revealed that the private pilot experienced difficulty maintaining altitude and airspeed while on final approach. Significant excursions above and below the glideslope were observed, along with large variations in airspeed.
Weather and Icing Conditions
Interviews with other pilots operating in the area just prior to and after the accident indicated that icing conditions existed in clouds near the airport. However, first responders to the accident site reported that there was no ice on the airplane.
Post-Accident Inspection
A post-accident inspection of the airplane, its engine, and flight navigation systems discovered no evidence of preimpact anomalies. An analysis of the airplane's navigation system light bulbs suggested that the pilot had selected the GPS mode for the initial approach but had not switched to the proper instrument approach mode to allow the autopilot to lock onto the ILS.
Probable Cause
The official probable cause is the pilot's failure to maintain sufficient airspeed to avoid a stall during an instrument final approach to land, which resulted in an inadvertent stall/spin. Factors associated with the accident are the inadvertent stall/spin, the pilot's failure to follow procedures/directives, and clouds.