What happened
On June 17, 2023, at 16:18 local time, a Cessna C172, registered as HB-CKU, departed from runway 34 at Buttwil Aerodrome (LSZU) for a planned one-hour recreational flight. The aircraft was carrying the pilot and three passengers. Shortly after lifting off, the aircraft entered a high angle of attack, causing it to bank sharply over the left wing. The aircraft subsequently struck the runway approximately 100 meters beyond the end of the runway. While the occupants of the aircraft remained uninjured, the aircraft sustained heavy damage.
The investigation
The investigation examined the aircraft's configuration, the pilot's training history, and the cockpit environment. At the time of the accident, the aircraft's weight and center of gravity were within permissible limits, and the flaps and elevator trim were set to the takeoff position. The stall warning system was found to be fully functional.
Investigators reviewed the pilot's training records, noting that while primary flight training had been completed successfully, a recent, undocumented qualification assessment contained highly negative feedback unknown to the pilot. Furthermore, while the pilot had received a brief familiarization on the Cessna C172 in April 2023, he had not flown this specific model since that training session. The investigation also noted the presence of an iPad mounted on the instrument panel, which was found with a dead battery.
Findings
Analysis of the flight path and video evidence confirmed that the aircraft entered an aerodynamic stall shortly after takeoff. Although the stall was visually apparent and the acoustic stall warning was triggered, the pilot failed to take corrective action, such as reducing the pitch angle, which would have recovered the aircraft.
Several contributing factors were identified:
- The pilot's perception of the developing stall may have been compromised by distraction from the mounted iPad.
- The use of a noise-canceling headset likely hindered the pilot's ability to perceive the acoustic stall warning.
- The pilot's limited recent experience with the Cessna C172 made it difficult to recognize and respond to the deviation from normal flight parameters.
- A lack of awareness regarding negative performance evaluations may have led to an inaccurate self-assessment of flight proficiency.