What happened
On 11 July 2015, during glider towing operations at Namur/Suarlée Airfield (EBNM), an Avions Pierre Robin DR400-180R landed with its tow cable still extended. After releasing a sailplane at an altitude of approximately 500 meters, the pilot activated the electrical winch to retract the cable. While the pilot initially checked the wing-mounted rearview mirror and saw the cable retracting, they failed to verify that the cable had reached its full, retracted position.
During the approach, the pilot chose to land on runway 24R rather than the parallel 24L to avoid an aircraft already on final approach. To avoid overflying a group of parked gliders, the pilot executed a low-altitude approach. During this maneuver, the extended cable struck a parked Grob G103 Twin II, resulting in structural damage to the glider's tail section, including the horizontal and vertical stabilizers and the elevator.
The investigation
The AAIU(Be) investigation examined the pilot's actions, the airfield's operational procedures, and the aircraft's equipment. Investigators found that the pilot did not hear radio warnings from the airfield supervisor or commander regarding the extended cable, likely due to heavy radio traffic.
Technical analysis of the winch system showed no mechanical failure; however, the investigation noted that the aircraft's flight manual supplement for the winch was written in German, a language not understood by most of the local pilots. Furthermore, an outdated French flight manual was also on board, which did not include information regarding the installed winch system.
Findings
- The pilot's failure to visually confirm the full retraction of the tow cable was the direct cause of the incident.
- The pilot's decision to land on a runway and safety area partially occupied by other aircraft led to a deviated flight path during the final approach.
- The airfield's internal rules and the towing operator's manual both permitted landing on runways or safety areas that were occupied by parked sailplanes.
- The BCAA's airfield approval process did not include an assessment of the airfield's internal operational procedures.
Safety action
Following the incident, the operator of the towing aircraft took steps to update the flight manual supplement to ensure it was accessible to the pilots. The AAIU(Be) issued recommendations to the BCAA to implement a system for verifying that airfield internal rules comply with prevailing regulations and to encourage dialogue between airfield operators, sailplane clubs, and the BCAA to ensure proper implementation of aerodrome safety standards.