What happened
On 15 July 2022, a JONKER JS1B glider, registered ZS-GDE, was performing a local flight near the Château-Arnoux - Saint-Auban aerodrome in France. After approximately 20 minutes of flight, the pilot decided to return to the aerodrome due to a lack of rising air.
While following the standard circuit for runway 20, the glider was on a normal approach path until reaching an altitude of approximately 65 meters. At this point, the glide slope increased sharply. In an attempt to reduce the rate of descent, the pilot retracted the air brakes; however, the aircraft continued to descend rapidly. Approximately 380 meters from the runway threshold, the glider struck the tops of trees, causing the right wing extension to tear off and forcing the aircraft into a spin and subsequent nose-first impact with the ground. The aircraft sustained substantial damage.
The investigation
The BEA examined the wreckage and recovered flight data from the aircraft's FLARM system. The investigation confirmed that the aircraft's flight controls and structure were fully functional prior to the impact, and no technical failures were identified. The wreckage was found near a road, roughly 350 meters from the runway threshold.
Data from the Open Glider Network (OGN) was analyzed for 23 other gliders that landed at the aerodrome shortly before the accident. While the paths of preceding aircraft were stable, the data for ZS-G2DE showed a significant increase in the glide slope from 13% to 24% during the final approach. Meteorological analysis revealed that the high temperatures and specific local geography were conducive to turbulence and wind shear.
Findings
- The primary cause of the accident was a sudden loss of altitude on short final, likely triggered by a localized aerological phenomenon such as wind shear or a sudden drop in airspeed and angle of attack.
- The pilot's attempt to retract the air brakes did not effectively mitigate the increased rate of descent.
- Local weather conditions, characterized by high temperatures and gusty winds, created an environment prone to ground-level turbulence.
- The glider was flying at a low altitude when the sudden change in lift occurred, leaving insufficient time for recovery before tree contact.