What happened
On July 2, 2004, a Grob G 103 Twin Astir 2 glider, registration F-CFKD, was performing a local flight at Saint-Affrique aerodrome. The glider was being towed by an aircraft for a takeoff from runway 30. Shortly after liftoff, while the glider was at an altitude of only a few meters near the central taxiway, the rear canopy unexpectedly opened.
This event caused the glider to climb higher than the tow plane. The pilot managed to correct the flight path but subsequently decided to release the tow cable. The pilot intended to perform a turn to land on the unpaved runway 12; however, the maneuver was unsuccessful. The glider touched down approximately 200 meters from the runway threshold, about 20 meters to the right of the centerline. The aircraft entered a ground loop before coming to a stop in a field of tall grass. There were no fatalities among the two occupants, though the aircraft was heavily damaged.
The investigation
The investigation focused on the cause of the canopy opening and the pilot's decision-making during the emergency. Investigators examined the canopy locking mechanism and found no mechanical anomalies or defects in the system.
Witnesses and the tow plane pilot estimated the cable release occurred at an altitude of approximately 50 meters, with the glider positioned vertically above the end of the paved runway 12 at the moment of release. The tow plane pilot noted that while the glider's position appeared abnormal, he could not see the specific issue in his rearview mirror and noted that no radio communication had taken place between the two aircraft during the flight.
Findings
Several contributing factors led to the accident:
- The pilot likely failed to fully secure the canopy latch, despite using a mnemonic checklist during pre-flight preparations.
- Distraction during pre-flight checks occurred because the pilot was preoccupied by the tow plane pilot assisting a passenger with their seating.
- The pilot was operating from the rear seat for the first time and was also flying with a passenger for the first time.
- The decision to release the cable was made too late, and the pilot overestimated the altitude available to complete the return maneuver.
- The club's recommended minimum release altitude of 100 meters does not account for the loss of aerodynamic efficiency caused by an open canopy.