What happened
On May 14, 2019, a Cessna 172P, registration HB-CGF, was conducting a training flight at Beromünster Airport (LSZO) when it lost control during the landing phase. The flight was intended as a positioning and training session for a pilot who had not flown for two years, accompanied by an instructor.
During the final approach, the pilot was managing a crosswind and turbulence caused by the Bise wind. While the pilot initially maintained the recommended approach speed, the airspeed dropped to approximately 60 KIAS. As the pilot reduced power and began to flatten the descent, the aircraft suddenly began to sink rapidly. Despite both the pilot and the instructor applying full power and the instructor pulling back on the elevator, the aircraft could not recover. The plane struck the ground in a barley field 65 meters before the start of runway 33, subsequently flipping onto its back. Both occupants escaped the wreckage without injury, though the aircraft sustained heavy damage.
The investigation
SUST examined the flight records, weather data, and the physical wreckage. The investigation focused on the meteorological conditions, specifically the wind speed and turbulence levels, as well as the flight parameters during the final approach. Investigators also reviewed the pilot's recent flight history and the technical state of the aircraft.
Findings
- The aircraft was in good technical condition with no mechanical failures contributing to the accident.
- The aircraft's weight and center of gravity were within approved limits.
- Meteorological conditions included a northeast wind of 10 knots with gusts up and to 18 knots, exceeding the aircraft's demonstrated crosswind component of 15 knots.
- The pilot selected an approach speed that was too low for the prevailing turbulent conditions and reduced power too early during the approach.
- The instructor's intervention to correct the sink rate occurred too late to prevent ground contact.
- The pilot had not flown for a period of two years prior to the accident.