What happened
On March 26, 2006, a Grob G103 C Twin III Acro glider, registration HB-3018, performed a forced landing at the San Vittore airfield in Switzerland. The pilot had been participating in a gliding camp and had completed a check flight with an instructor the previous day after a six-month hiatus from flying.
During the final approach to runway 26, the pilot initially deployed the airbrakes to 20% extension while maintaining a speed of 105 km/h. Upon encountering a gust, the pilot perceived a sudden drop in wind and reacted by retracting the airbrakes and increasing speed to 120 km/h to prevent a short landing. During this maneuver, the pilot unintentionally locked the airbrake lever in the retracted position. Believing the airbrakes were malfunctioning, the pilot attempted to land using only the wheel brake. The aircraft struck the grass runway at excessive speed, bounced multiple times, and sustained significant damage, including a detached tail section.
The investigation
The investigation focused on the pilot's flight history, the aircraft's mechanical state, and the meteorological conditions at the time of the accident. Investigators examined the pilot's training records, noting that while the pilot held a valid license, they had not flown for approximately six and a half months prior to the accident. The check flight conducted the day before the accident did not include specific training exercises or intensive landing practice.
Technical inspections of the HB-3018 revealed no pre-existing mechanical defects. The airbrakes and wheel brakes were found to be fully functional following the impact. Meteorological data confirmed sunny conditions with light valley winds from the west at 15 to 20 km/h.
Findings
- The primary cause of the accident was an unstabilized approach combined with the improper use of flight controls.
- The pilot's recent training level was low due to a significant six-month break in flying activity.
- The preceding check flight was insufficiently demanding, failing to identify the pilot's lack of proficiency or provide necessary landing practice.