What happened
On March 24, 2018, an MCR-ULC was operating a private glider towing mission at Beromünster Airport (LSZO). During one of the towing flights, the pilot experienced an unusually long landing on the grass runway. In an attempt to compensate for this during a subsequent flight, the pilot initiated a landing maneuver that resulted in the aircraft touching down approximately five meters before the start of the runway on soft ground. Upon impact with the soft terrain, the pilot felt a sudden, intense braking force. While the aircraft continued its rollout onto the runway normally, the impact caused structural damage.
The investigation
The investigation was delayed because the incident was not reported immediately to the Swiss Transportation Safety Investigation Board (SUST) as required by regulation. The pilot initially submitted the report through the Federal Office of Civil Aviation (BAZL) portal, which then forwarded the information to SUST several days later. Consequently, investigators were unable to perform an immediate on-site inspection. A post-incident inspection of the aircraft revealed cracks on the underside of the left wing near the wing root, as well as cracks on the right wing and the right side of the fuselage, also located near the wing root.
Findings
- The aircraft was reported to be in technically sound condition prior to the event.
- The primary cause of the incident was a short landing driven by the pilot's operational decision to correct a previous landing error.
- The impact with the soft ground before the runway threshold caused the observed structural cracks.