Accident Overview
During an instrument approach to a runway in an approaching winter storm, the pilot flew through the approach course multiple times, staying consistently below the glideslope path. The airplane continued below the published decision height and drifted to the right of the extended centerline. The pilot initiated a missed approach, but the onboard GPS recorded a rapid decrease in ground speed followed by a descent to the ground, consistent with an aerodynamic stall.
Witness and Physical Evidence
The airplane owner, who was also a passenger, stated that after the pilot completed two left turning circles and began a third, he perceived the airplane "just stalled." Post-accident examination of the airframe and engine found no preimpact anomalies that would have prevented normal operation. However, the airplane's anti-ice and propeller anti-ice switches were found in the "off" position.
Weather Conditions
Weather information indicated that the airplane was operating in an area with potential for moderate icing and snow. Based on GPS data and weather conditions, it is likely that airframe ice accumulated during the descent and approach, affecting the airplane's performance and leading to the aerodynamic stall during the climb.
Probable Cause
The official probable cause is the pilot's inadvertent stall during a missed approach. A contributing factor was the pilot's operation of the airplane in forecasted icing conditions without using all of its anti-ice systems.