What happened
On the afternoon of March 21, 2000, a Glaser Dirks DG600M motor glider, registration D-KBSJ, departed from Sisteron aerodrome for a flight around Mont Blanc. The pilot was flying in company with another aircraft. Around 15:30, the second pilot ended their flight due to insufficient lift, but the pilot of D-KBSJ continued traveling north.
At approximately 15:00, witnesses reported hearing the pilot announce their position on the radio, vertically above a turning point east of the accident site. The wreckage was eventually located on the northwest slope of the Col de Pelouse, roughly 40 meters from the summit. The distribution of debris and analysis of the structural failures indicated that the aircraft struck the terrain at a steep angle, nearly vertical, while executing a left-hand turn.
The investigation
The investigation focused on the flight path and the aerodynamic conditions at the time of the impact. While the exact trajectory could not be determined, investigators examined the local topography and wind conditions. At the time of the accident, the wind was estimated to be from 180° at 10 to 15 knots, with CAVOK visibility conditions.
Investigators noted that when winds originate from the south, downdrafts are generated on the leeward side of the ridge. The wreckage was found on the leeward side of the Col de Pelouse. Additionally, the emergency locator transmitter (ELT) was recovered near the wreckage; although the switch was in the 'off' position, testing confirmed the device was fully functional.
Findings
- The aircraft likely encountered downdrafts while attempting to cross or passing through the mountain pass at an insufficient altitude.
- To compensate for the loss of altitude, the pilot likely applied back pressure on the control column.
- This maneuver resulted in an asymmetric stall at a low altitude.
- The impact was fatal to the one pilot on board, and the aircraft was destroyed.