What happened
On 2 September 2020, a Robin DR400-180R, registered F-HKZZ, was performing a glider tow at Bagnères-de-Luchon aerodrome. Shortly after departing from runway 01, the aircraft was flying at an airspeed higher than recommended for the specific glider being towed, a Schleicher Ka 6E (registration F-CDRM).
During the initial climb, the tow cable slackened and then suddenly became taut. This caused the glider to pitch up sharply, rising approximately 10 meters above the level of the tug plane. The sudden increase in tension and the glider's upward movement caused the aeroplane to lose speed and adopt a nose-down attitude. Although both pilots released the tow cable simultaneously, the aeroplane pilot was unable to recover from the descent and the aircraft collided with the runway. The impact resulted in one severe injury to the aeroplane pilot and the destruction of the aircraft. The glider pilot sustained one injury and the glider suffered minor damage.
The investigation
The BEA examined wreckage, FLARM and OGN flight data, and witness statements. The investigation focused on the flight dynamics of the tow combination and the aerodynamic characteristics of the Schleicher Ka 6E. Investigators noted that the glider's tow hook is located near its center of gravity, a position that does not assist in path correction if the glider deviates from the tug's path. Data analysis showed that the ground speed of the combination dropped from 110 km/h to 70 km/h during the critical phase when the glider ascended.
Findings
Several factors contributed to the accident:
- The takeoff was performed at an airspeed of approximately 130 km/h, which was significantly higher than the 110–115 km/h recommended for this glider type.
- The glider rose above the tug plane due to a combination of high airspeed, turbulence from valley breezes, and the glider's unstable pitch attitude.
- The pilots failed to confirm the required towing speed during their pre-takeoff radio contact.
- The late release of the tow cable contributed to the loss of control of the aeroplane.
- The glider's tow hook position near the center of gravity made it difficult to stabilize the aircraft once the deviation occurred.