What happened
On June 14, 2012, at 15:16 local time, a mid-air collision occurred near Curienne, France, involving a Centrair 101 glider, registered F-CHFM, and a Silent 2 Electro ultralight, identified as 01-ACO.
The sequence of events began at 14:54, when the pilot of the F-CHFM glider departed via winch launch from the unpaved runway 32 at Chambéry Challes les Eaux aerodrome. The glider proceeded east toward mountainous terrain, maintaining an altitude of approximately 3,000 ft. Approximately five minutes later, the pilot of the 01-ACO ultralight departed and joined the same mountainous area, which was also occupied by several other gliders.
The glider pilot reported crossing the path of the ultralight twice without detecting the aircraft on his Flarm collision avoidance system. During a right-hand turn, the glider pilot experienced a sudden impact that forced the aircraft downward. Fearing a loss of control, the pilot briefly considered abandoning the aircraft but managed to recover control and land safely on runway 32. The ultralight, however, struck the ground with its engine not delivering power at the moment of impact.
The investigation
Investigators examined both aircraft to determine the mechanics of the collision. The inspection revealed that the impact occurred between the rear elevator of the Centrair 101 and the right wingtip of the Silent 2 Electro.
While both aircraft were equipped with Flarm technology, the investigation established that the system in the glider was operational, whereas the Flarm unit in the ultralight was not powered on during the flight. The pilot of the ultralight was performing his first flight in this recently acquired aircraft. Although the pilot had participated in weather briefings and received takeoff authorization, his experience in this specific type was minimal.
Findings
- The primary cause of the accident was the failure of the ultralight pilot to visually detect the glider.
- The failure to activate the Flarm system on the 01-ACO deprived both pilots of critical anti-collision information.
- The pilot's lack of familiarity with the aircraft's systems during his maiden flight contributed to the oversight.
- The decision to operate in a mountainous sector already occupied by multiple gliders further contributed to the collision.