What happened
On the afternoon of June 25, 2011, a Rolladen-Schneider LS 6 glider, registration G-DHEZ, departed from the Serres La Batie airfield for a local flight. The pilot, who held a UK-issued gliding license with 600 total flight hours, was flying near the southwest flank of the Cirque des Monges.
At approximately 17:00 local time, the aircraft was flying along the edge of the cirque at an altitude below the surrounding ridge line. While executing a left-hand turn to return toward the ridge, the pilot experienced a sudden loss of altitude due to sinking air. Despite attempts to maneuver away from the terrain, the glider struck the slope. The impact resulted in one injury to the pilot and significant damage to the aircraft.
The investigation
The investigation focused on the flight path, the meteorological conditions, and the aircraft's state at the time of impact. Examination of the wreckage revealed that the Rolladen-Schneider LS 6 struck the slope in a level attitude while in a left-hand turn. The pilot reported that the aircraft was traveling at a low airspeed when the sink rate increased.
Meteorological data at the site indicated a wind from 070° at 15 to 20 knots, with CAVOK conditions and a temperature of 21°C. Investigators determined that the aircraft was positioned on the lee side of the terrain, specifically within a zone of downdrafts (katabatic winds) created by the mountain topography. Although the glider was equipped with a FLARM proximity indicator, the data from this device could not be retrieved for analysis.