What happened
On August 24, 2010, a Jodel D11 (Uetz), registration HB-SUY, was conducting a flight training session at Speck-Fehraltorf airfield in Switzerland. The flight, involving a flight instructor and a student pilot, was intended to include various maneuvers, specifically focusing on emergency procedures and simulated engine failures.
During the final approach to runway 30, the student pilot initiated a right-hand sideslip to maintain visual contact with a fixed point on the airfield. As the aircraft descended, the instructor took control of the aircraft to initiate a go-around procedure. However, the aircraft failed to arrest its descent despite the application of full power. The aircraft rolled to the left, causing the left wing to strike the ground outside the left runway boundary. The aircraft subsequently slid through tall grass for approximately 250 meters before coming to a halt. While the occupants were uninjured, the aircraft sustained significant damage, including a broken left wing spar.
The investigation
SUST examined the technical condition of the HB-SUCT, finding no evidence of mechanical failure or pre-existing technical defects. The investigation confirmed that the engine responded immediately to full power during the attempted go-around.
Investigators also analyzed the meteorological conditions at the time of the accident. A cold front had recently passed through the region, leaving behind a highly turbulent atmosphere characterized by strong west-northwest winds of approximately 20 knots, with gusts reaching up to 30 knots. The investigation focused on the decision-making process regarding the suitability of performing high-workload emergency maneuvers in such unstable wind conditions.
Findings
- The primary cause of the accident was the loss of control during the recovery from a sideslip on final approach, leading to ground impact.
- The flight instructor's takeover of the controls and the subsequent initiation of the go-around occurred too late to prevent the collision.
- The planning and execution of the emergency landing exercise were inappropriate given the prevailing high-wind and turbulent weather conditions.
- The student pilot's choice of a right-hand sideslip, while intended to maintain a visual reference, increased the difficulty of the approach due to the prevailing wind direction.