- Location: Pinedale, Wyoming
- Accident Number: WPR25LA029
- Date & Time: October 29, 2024, 16:45 Local
- Registration: N885CA
- Aircraft: Daher TBM700
- Aircraft Damage: Substantial
- Defining Event: Structural icing
- Injuries: 1 Serious, 6 Minor
- Flight Conducted Under: Part 91: General aviation - Personal
https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/195417/pdf
https://data.ntsb.gov/Docket?ProjectID=195417
On October 29, 2024, about 1645 mountain daylight time, a Daher TBM 700N (marketed as the TBM 850) airplane, N885CA, was substantially damaged when it was involved in an accident near Pinedale, Wyoming. The pilot and five passengers sustained minor injuries, and one passenger sustained serious injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
After landing, the airplane was refueled, and six passengers boarded. During the airplane's approximately 15-minute ground stop, a witness observed that heavy, wet snow was falling. Before taxi, the pilot used a foam brush to remove snow from the airplane. The witness further observed snow contamination on an outboard wing section after the pilot finished brushing the airplane.
Heavy snowfall continued as the airplane taxied but diminished by the time the airplane began its takeoff roll. During rotation, the airplane became airborne briefly before the left wing dropped and struck terrain.
According to the airplane's pilot's operating handbook (POH), even small accumulations of snow, frost, or ice must be removed from the wings, tail, and control surfaces during the preflight inspection. The POH also called for anti-icing fluid shortly before takeoff from a snow-covered runway. The risks of snow and ice accumulation were also addressed in a 2018 service letter (SL) from the airplane manufacturer, which stated that takeoffs with snow or ice adhering to the wings should not be attempted because such contamination could drastically affect performance due to reduced aerodynamic lift and increased drag resulting from disturbed airflow. The SL also provided recommendations for ground deicing and anti-icing procedures and emphasized the need for a pre-takeoff contamination inspection.
The left wing drop shortly after liftoff was consistent with an aerodynamic stall. The stall was likely the result of snow contamination that remained on the wing after the pilot brushed the airplane; the amount of snow on the wing also likely increased as snow continued to fall during taxi. The contamination reduced aerodynamic lift and increased drag, which resulted in a loss of control shortly after takeoff. Because snow continued to fall during taxi, the lack of anti-icing fluid also left the cleaned surfaces exposed to renewed accumulation. Although Type I fluid was available for deicing, the manufacturer cautioned that it would provide inadequate anti-icing protection during snowfall unless takeoff followed deicing almost immediately. The other fluid reportedly available, Type IV, was unsuitable for this airplane. The absence of preimpact mechanical failures or malfunctions further supported an aerodynamic, rather than mechanical, explanation for the loss of control. A review of two previous accidents involving the same airplane type and similar circumstances revealed similar left-wing drops shortly after liftoff.
The pilot's reported rotation speed of 85 knots was slightly below the charted rotation speed of about 87 knots for the airplane's reported takeoff weight. Rotating early likely further reduced the airplane's safety margin during liftoff.
- Probable Cause: The pilot's failure to ensure that the airplane was free of snow contamination before takeoff and to follow the manufacturer's anti-icing procedure during continued snowfall, which resulted in an aerodynamic stall and loss of control shortly after liftoff. Contributing to the accident was the pilot's rotation below the manufacturer's recommended rotation speed.
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