What happened
On 13 October 2021, a GLASER DIRKS DG 600-18 M glider, registration D-KIHR, was being prepared for a morning wave soaring flight near the Pyrenees. The pilot intended to be towed by a Dynamic WT9 microlight to an altitude of 3,000 meters.
During the takeoff roll at Saint-Gaudens aerodrome, the tug pilot experienced significant difficulty controlling the microlight, noting a leftward pull and a nose-down attitude. As the glider rose higher than the tug, the tug pilot released the tow cable to maintain control of the microlette. The glider pilot released the cable almost simultaneously and attempted a left-hand turn to return to the runway. During this maneuver, the glider lost control and collided with a grove of trees approximately 250 meters from the end of the runway. The pilot of the glider sustained fatal injuries, and the aircraft was destroyed.
The investigation
The BEA examined the flight paths, wreckage, and meteorological conditions. The investigation established that the glider's ground speed during takeoff reached 130 km/h, but it slowed to approximately 80 km/h after the cable release. During the final turn, the glider maintained a bank angle of roughly 40% with a turning radius of 60 meters. Calculations indicated that at this bank angle, the stall speed increased, making a stall highly probable at the recorded speed of 70 km/h.
Investigators also looked into the visibility conditions. On the morning of the accident, the sun was low on the horizon, and the ambient humidity was high. The investigation noted that the glider lacked a cabin heating system, relying instead on an outside air bleed. This lack of heat, combined with the pilot's respiration, likely caused condensation to form on the inside of the canopy.
Findings
- The primary cause of the accident was the glider entering a turn at a low altitude and high bank angle, which led to a stall and subsequent loss of control.
- The tug pilot was forced to release the cable because the glider had risen above the level of the microlight, creating an unstable towing configuration.
- A loss of external visual references likely contributed to the pilot's inability to maintain the flight path. This was potentially caused by mist on the glider canopy or the pilot's glasses, exacerbated by the glare from the low morning sun.