What happened
On September 13, 2013, a Glaser Dirks DG-800B glider, registration D-KLMA, was performing a private flight near Lles de Cerdanya, Spain. The flight began with a winch or aero-tow launch, releasing the aircraft at approximately 2,100 meters near Meranges. After utilizing several thermals to reach an altitude of 2,900 meters, the pilot proceeded west toward Lles de Cerdanya in search of further lift.
Upon approaching a potential thermal, the pilot observed the variometer indicating an ascent and turned into the suspected updraft. However, instead of rising, the aircraft encountered a strong descending air current of approximately 10 m/s. This sudden loss of altitude forced the pilot to dive to maintain airspeed. Realizing there was insufficient altitude to clear the surrounding mountains and exit the valley, the pilot prepared for an emergency landing.
Finding no clear landing zone, the pilot attempted to fly between two trees, intending to use the impact with the branches to bleed off airspeed. The aircraft struck the trees, causing the wings to sustain significant damage, the tail section to detach due to fuselage failure, and the nose to be destroyed. The glider ultimately came to rest upside down on the ground. The pilot sustained only minor injuries.
The investigation
The investigation examined the flight path, the meteorological conditions, and the terrain of the "Clot de la Caülla" valley. Investigators estimated the aircraft was at an altitude of approximately 2,600 meters when it encountered the downdraft. The analysis focused on the pilot's maneuvers, specifically the decision to dive to gain speed and the attempt to navigate toward a larger valley. The investigation also reviewed the local topography, noting that the flat nature of the valley floor prevented the pilot from utilizing descending terrain to maintain flight.
Findings
- The aircraft encountered an unexpected and intense downdraft while maneuvering for lift.
- The aircraft's altitude was slightly lower than typical flight levels for the area at the time of the encounter.
- The specific topography of the valley floor provided no descending terrain to assist the pilot in maintaining altitude.
- The combination of the intense sink rate and the terrain prevented the pilot from successfully exiting the valley.