What happened
On May 16, 2017, at approximately 10:24 UTC, an L 23 Super-Blanik glider, registration OK-023 and 39, was performing basic flight training at Benešov airfield (LKBE). The flight was part of a training syllabus specifically focused on correcting failed landings.
The student pilot had recently been assigned a new instructor following feedback from previous sessions regarding delayed and heavy-handed control inputs. During the third flight of the day, the instructor intentionally executed a high flare to test the student's ability to react promptly by closing the airbrake and pushing the control stick forward to maintain a proper descent angle.
While the student closed the airbrakes immediately, they reacted to the instructor's prompt with an excessive and abrupt forward movement of the control stick. This sudden input caused the glider to transition into an improper, steep descent angle. At a height of approximately 1.5 to 2 meters and a speed of roughly 80 km/h, the nose of the aircraft struck the grassy surface of runway 27, approximately 170 meters from the threshold. The aircraft then bounced and continued along the runway before coming to a stop. There were no injuries to the student or the instructor.
The investigation
The ÚZPLN investigation examined the flight sequence, the training history of the student, and the physical condition of the aircraft. The investigation established that the student had been struggling with late reactions in previous flights with a different instructor. The new instructor was aware of these issues and had briefed the student specifically on the necessity of timely reactions during the maneuver.
Post-accident inspections of the L 23 Super-Blanik revealed significant structural damage, including deformation of the right wing's leading edge skin, damage to the wing-to-fuselage attachment, and a torn fuselage skin at the junction of the fuselage and the keel leading edge. Meteorological data confirmed that weather conditions, including visibility and wind, were well within the aircraft's operating limits and were not contributing factors.
Findings
- The student pilot's high level of motivation to correct previous errors led to an overcorrection during the maneuver.
- The student's reaction to the instructor's prompt was excessively abrupt and heavy-handed.
- The instructor, despite having a hand on the controls, was unable to intervene in time to counteract the student's sudden control input.
- The primary cause of the accident was the instructor's failure to react in the prescribed manner and in time to the student's heavy control input.