What happened
During an instrument approach to the runway, the pilot encountered an approaching winter storm. Analysis of GPS data revealed that the aircraft type repeatedly crossed the approach course and remained below the established glideslope throughout the procedure. As the flight continued, the aircraft descended below the required decision height altitude and drifted right of the runway centerline. The GPS records indicate that the pilot attempted a missed approach, followed by a sharp reduction in ground speed and a descent into the ground. A passenger on board observed the aircraft performing turning circles before it appeared to stall.
Findings
An inspection of the engine and airframe revealed no mechanical issues or pre-impact anomalies that would have prevented the aircraft from functioning normally. However, investigators noted that the anti-ice and propeller anti-ice systems were set to the off position. The flight occurred in an area where moderate snow and icing were possible. It is determined that ice accumulation on the airframe likely occurred during the approach and descent, which degraded the aircraft's performance and ultimately triggered an aerodynamic stall during the missed approach attempt.