Incident Overview
On May 16, 2017, at 10:24 UTC, a two-seat L-23 Super-Blaník glider with registration OK-0239 experienced an accident at Benešov airfield in the Czech Republic. The aircraft was operated by LET, a.s., and was engaged in basic flight training. During the incident, the glider struck the grassy surface of Runway 27 with its nose, resulting in significant structural damage but no injuries to the crew.
Operational Context
The pilot-instructor, a 64-year-old male, and the student pilot, a 59-year-old male, were conducting training exercises focused on correcting bad landings. The student had previously flown this task with another instructor who noted issues with delayed reactions and rough control inputs. For this session, the new instructor briefed the student on proper correction techniques. They completed three aerotow launches, reaching altitudes between 350 and 400 meters above ground level.
Sequence of Events
During the third and critical flight, the instructor intentionally performed a high bounce to test the student's reaction time and accuracy in correcting a bad landing. The student reacted quickly but applied excessive force to the control stick while closing the brake flaps. This abrupt input caused the glider to enter an inappropriate descent angle at a low altitude of approximately 1.5 to 2 meters above the runway. At a speed of roughly 80 km/h, the nose of the aircraft struck the ground about 170 meters from the threshold of Runway 27.
Damage and Investigation Findings
Post-incident inspections revealed deformation of the skin on the leading edge of the right wing half and damage to the upper spine of the fuselage near the fin transition. The Czech Institute for Expert Determination of Causes of Aviation Accidents (ÚZPLN) determined that the accident resulted from the student pilot's improper reaction during the correction of a simulated bad landing. The investigation was conducted in accordance with EU Regulation 996/2010 and focused solely on safety prevention without assigning liability.