Synopsis
On 11 July 2015 at 12:20 UTC, a serious incident occurred at the airfield of Namur/Suarlée (EBNM) involving a Robin DR400-180R towing aircraft and a parked Burkhart Grob Flugzeugbau GMBH G103 Twin II sailplane. The DR400, which had just released a glider at 500 m altitude, landed with its tow cable still extended. The cable hit the parked Grob Twin II, causing structural damage to its tail section. No injuries were reported.
History of the Flight
After releasing the glider, the pilot operated the electrical winch to retract the tow cable and checked the rear-view mirror on the wing to confirm retraction, but did not verify that the cable was fully retracted. While on downwind, the pilot called the glider operations supervisor to discuss refuelling; no mention was made of the extended cable. The pilot elected to land on runway 24R (the glider runway) instead of parallel runway 24L because another aircraft was ahead on 24L. On final approach, the pilot saw a group of gliders near the threshold of 24R and a Grob Twin II positioned on the left side of the runway axis. He attempted a low final to perform a short landing and avoid the gliders. Meanwhile, the glider operations supervisor and the airfield commander noticed the extended cable and tried to radio the pilot, but the pilot did not hear the calls due to a busy frequency.
Cause
According to the investigation, the direct cause was the pilot's failure to visually check the full retraction of the tow cable after releasing the sailplane. The indirect causes included the pilot's decision to land on a runway and/or safety areas partially occupied by sailplanes, resulting in a deviated flight path on final, and the airfield's internal rules of procedure that allowed landing on an occupied runway. A contributing factor was the BCAA's approval of the airfield without assessing its internal rules of procedure.
Aircraft and Pilot Information
The Robin DR400-180R (serial number 1117) was owned by the association “Les Ailes Namuroises SCRL” and used for glider towing. The pilot was a 41-year-old Belgian male with a private pilot licence, SEP (land) rating with sailplane towing endorsement, and a glider pilot licence. He had 690 flight hours total (PIC). The aircraft was equipped with a retractable tow cable winch (Feuerstein system). The flight manual supplement (in German) described the cable retraction procedure, but the manual was not used by most pilots as they did not understand German; the French manual on board only covered a different winch system.
Airfield Information
EBNM Namur airfield is located 7 km west-northwest of Namur. It has two grass runways: 06L/24R (630 m x 50 m, primary for gliders) and 06R/24L (695 m x 31 m, primary for motorized aircraft). Both runways with orientation 24 have right-hand circuits. The runway strips extend 60 m wide and 30 m beyond each runway end; RESAs extend 30 m further. The use of the aerodrome is subject to prior permission. Operations include aeroplanes, helicopters, gliders, and parachuting in VMC. Radio communication on 118.000 MHz is mandatory, with a restriction against personal conversations on the frequency.
Injuries and Damage
No injuries were reported. The Grob Twin II sailplane sustained structural damage to its tail section.
Probable Cause
According to the investigation, the direct cause was the failure of the pilot to visually check the full retraction of the tow cable after releasing the sailplane.