What aircraft was involved and where did it happen?

The accident on 2006-07-30 involved a Duo Discus, registration F-GACP, at FR.

What was the probable cause of the accident?

The collision was caused by the failure of both pilots to detect each other, exacerbated by the towplane pilot's direct flight path and the sun's position obscuring the view, alongside a lack of traffic detection technology and club oversight.

Mid-air collision between glider and towplane near Sisteron

A mid-air collision between a Schempp Hirth Duo Discus glider and a Socata Morane Saulnier Rallye 235 E towplane resulted in three fatalities near Valernes, France.

What happened

On July 30, 2006, at approximately 11:38 UTC, a mid-air collision occurred near the Rocher de Hongrie in the commune of Valernes. The aircraft involved were a Schempp Hirth Duo Discus glider, registration F-CIDG, and a Socata Morane Saulnier Rallye 235 E towplane, registration F-GACP.

The glider was performing local flight maneuvers at an altitude of approximately 1,000 meters, while the towplane was returning to the Sisteron aerodrome after having released a different glider at 1,180 meters. During the descent, the towplane entered a collision course with the glider, striking it from the upper left side. The impact caused significant damage to the glider's vertical stabilizer and right wing. Both aircraft subsequently crashed into the terrain, with the towplane's wreckage being destroyed by the impact and a subsequent fire. The collision resulted in three fatalities: the pilot and passenger of the glider, and the pilot of the towplane.

The investigation

The investigation examined the flight trajectories, weather conditions, and the operational environment of the aero club. Investigators utilized GPS data from the glider to reconstruct the flight paths. Witnesses, including other glider pilots and a ground observer, provided accounts of the aircraft's movements.

Physical examination of the wreckage revealed that the towplane's engine struck the ground first, followed by the aircraft flipping onto its back. On the glider, the investigation noted structural failures in the tail and wing, as well as traces of blue paint and rubber from the towplane's landing gear on the glider's airframe. The investigation also looked into the club's safety management and the historical flying habits of the towplane pilot, noting reports of aggressive maneuvering following releases.

Findings

The primary cause of the collision was the failure of both pilots to detect the presence of the other aircraft despite the requirement for visual surveillance.
The towplane pilot's decision to take a direct path back to the aerodrome increased the probability of an encounter with other gliders in the area.
The position of the sun relative to the glider pilot's field of view likely hindered the detection of the approaching towplane.
The lack of onboard traffic detection systems on both aircraft contributed to the inability to alert the crews to the imminent conflict.
A lack of formal oversight for towplane pilots and the absence of a dedicated flight safety structure within the aero club were identified as contributing factors.

Safety action

The BEA recommended that aero clubs implement formal oversight structures for towplane pilots to manage individual flight behaviors.
The BEA recommended that the DGAC, in coordination with EASA and gliding associations, work toward the widespread use and standardized installation of onboard traffic detection systems.
The BEA suggested that the DGAC and aviation federations study the implementation of flight safety structures within aero clubs to better manage recreational flying risks.