What happened
On November 11, 2022, a flight training session was underway at Amendoeira Aerodrome involving a PZL-Swidnik PW-6U glider, registration D-5159. The flight was an aerotow operation, with a Morane-Saulnier MS.893A Rallye (registration D-EMZO) acting as the towing aircraft. A visiting pilot, assisting with ground preparations, had attached the 50-meter tow rope to both the glider and the towing aircraft, performing checks to ensure the connections were secure.
During the second takeoff roll of the session, the glider was being piloted by a student pilot with an instructor in the rear seat. Shortly after crossing the N114 road and reaching an altitude of approximately 25 meters, the tow rope detached from the towing aircraft. The student pilot reported a sudden, significant rightward bank and a loss of control effectiveness. While the instructor attempted to take control and execute a 180-degree turn to return to the runway, the aircraft's right wing struck the ground. The glider transitioned into a lateral, descending motion, dragging the wingtip along the terrain before the fuselage struck the ground violently in a nose-down attitude.
The investigation
The investigation examined the mechanical state of the towing equipment and the sequence of the flight. Investigators analyzed the 50-meter tow rope and found that while the end attached to the glider failed at the weak link during the ground collision, the end attached to the towing aircraft remained intact with the weak link and attachment ring undamaged. Tests confirmed that the Tost system release hook on the glider functioned correctly. The investigation also reviewed the maintenance and airworthiness status of the towing hook installed on the aircraft D-EMlam (D-EMZO), noting concerns regarding the unairworthy condition of the component.
Findings
- The primary cause of the accident was the inadvertent and premature release of the tow rope from the towing aircraft.
- The investigation identified that the towing hook on the Morane-Saulnier MS.893A Rallye was in an unairworthy condition.
- The student pilot experienced a sudden loss of control and was unable to maintain altitude following the separation.
- Both the instructor and student pilot sustained minor injuries to the head, neck, and spine, though they were not wearing energy-absorbing seat cushions.
- The glider sustained substantial structural damage, including a broken wing spar and a fractured tail boom.
Safety action
- Safety recommendation PT.SIA 2023/08: It is recommended that EASA, within 24 months, provides greater emphasis and detail regarding flight control handover protocols during theoretical and flight instruction for Sailplane Pilot License (SPL) students, amending the relevant AMCs and GMs to Part-SFCL.