What happened
On October 18, 2009, a professional pilot was performing a repositioning flight in an AT-3 R100, registration SP-TPG, from Konstancin to Sobienie Szlacheckie. The flight was conducted under VFR conditions in visual meteorological conditions (VMC) during daylight hours.
During the landing phase at Sobienie Szlacheckie, the pilot executed a landing approach on runway 090 with a light northern wind. Due to a slightly flat approach trajectory, the pilot increased engine power to ensure the aircraft reached the runway threshold. The aircraft touched down just past the threshold with an excessive sink rate, causing the aircraft to bounce to a height of approximately 1–2 meters. Following this bounce, the aircraft drifted left by about 15 degrees.
In an attempt to maintain direction and reduce the sink rate, the pilot increased engine power further. However, the aircraft's heading deviated further to approximately 30 degrees. As the pilot applied additional power to initiate a go-around, the aircraft experienced a significant left bank of approximately 20 degrees. The left wing struck a fence, causing the fuselage nose and then the right wing to impact the ground. The aircraft subsequently flipped onto its back. There were no injuries to the pilot or the passenger, though the aircraft was destroyed.
The investigation
The PKBWL investigation examined the flight trajectory, the aircraft's mechanical response to power changes, and the pilot's actions. The investigators analyzed the aerodynamic effects of the engine's slipstream and torque on the aircraft's stability during the low-speed ground roll. The investigation also reviewed the pilot's familiarity with the specific handling characteristics of the AT-3 R100 during high-power, low-speed maneuvers.
Findings
- The initial approach was too short, necessitating a power increase that disrupted the landing stability.
- The aircraft touched down with an excessive sink rate, triggering a bounce.
- The primary cause was the decision to land with a bounce and subsequent loss of directional control, which, combined with inadequate pilot response, led to a significant deviation and bank into an obstacle.
- Increasing engine power created an asymmetric slipstream effect on the rudder and increased propeller torque, which exacerbated the leftward yaw and roll.
- At low speeds, the aerodynamic effectiveness of the flight controls was significantly reduced, a characteristic inherent to this aircraft type when equipped with a high-power engine.
- The pilot's actions were inadequate to recover from the developing situation, likely due to a lack of familiarity with the aircraft's specific aerodynamic tendencies during such maneuvers.