What happened
On 9 October 2024, a pilot operating a Socata TB9, registration SP-FNL, attempted a takeoff from the wet grassy runway at Zborowo airfield (EPZB). The flight was planned with three passengers. Due to approaching low clouds and rain, the pilot had kept the engine running at idle for approximately 35 minutes while waiting for the weather to improve.
As the aircraft accelerated down the runway, it experienced an unusually long takeoff run, reaching 650 meters before reaching 60 knots. Upon reaching this point, the pilot attempted to rotate the aircraft. The aircraft climbed only 2 to 3 meters before the pilot, attempting to avoid a house ahead, initiated a left turn. During this maneuver, the pilot pulled the control column back significantly, inducing a sudden increase in the angle of and a dynamic stall. The aircraft's tail struck the runway, causing the plane to roll onto its right wing and strike two fences before coming to a stop. There were no fatalities and no injuries to the pilot or passengers, though the aircraft sustained substantial damage, including the separation of the left wing.
The investigation
The PKBWL investigation examined the aircraft's technical condition, the pilot's weight and balance calculations, and the meteorological conditions at the time of the accident. The investigation reviewed the engine's performance, the fuel used, and the pilot's previous experience with the Socata TB9. Investigators also analyzed the aircraft's mass and center of gravity (CG) relative to its maximum takeoff mass (MTOM) and evaluated the likelihood of carburetor icing given the high humidity and prolonged idling.
Findings
- The aircraft's MTOM was exceeded by 34 kg because the pilot used an incorrect empty mass of 650 kg instead of the actual 685 kg in his calculations.
- The aircraft's center of gravity was positioned at the extreme rear of the allowable envelope, contributing to a nose-up tendency.
- Carburetor icing was a probable factor, as high humidity and a long period of engine idling likely reduced engine power, extending the takeoff run.
- The pilot failed to abort the takeoff after the run exceeded the expected length for a wet, grassy surface.
- The pilot had very limited experience with this specific aircraft type, having performed only one prior 40-minute familiarization flight.