What happened
On 7 July 2010, during the fourth day of the Spanish national gliding championships in Huesca, an Alexander Schleicher ASW 27-18E, registration D-KANR, crashed into the southwest flank of Pico Cebolles. The aircraft was participating in a cross-country race, flying through mountainous terrain in the Pyrenees.
At approximately 15:52 local time, the pilot was flying at an altitude of roughly 2,200 m, navigating near a hillside. Flight data recovered from an onboard logger indicates that the pilot was attempting to utilize a thermal updraft. As the aircraft approached the terrain, the pilot initiated a turn to the right. During this maneuver, the aircraft's speed dropped from 140 km/h to 110 km/h, and the climb rate fluctuated significantly. The aircraft ultimately impacted the terrain at a high angle and high speed, resulting in one fatality and the total destruction of the sailplane.
The investigation
The CIAIAC investigation focused on reconstructing the flight path and aerodynamic state of the aircraft using data from a Filser LX 8000F logger. Investigators examined the aircraft's configuration, noting it was equipped with water ballast to increase wing loading for competition performance. The investigation also reviewed the pilot's extensive experience and the meteorological conditions, which featured moderate thermal updrafts and good visibility.
Technical analysis of the wreckage and the flight data allowed investigators to rule out mechanical failure of the rudder, bird strikes, or prior collisions with terrain. The investigation specifically looked at the relationship between the aircraft's weight, flap settings, and the load factors generated during the turn.
Findings
- The pilot was highly experienced in mountain flying and was fully qualified for the flight.
- The aircraft was airworthy and had no known mechanical defects.
- The glider was flying with water ballast, which increased its takeoff weight to 533.2 kg.
- The pilot was flying in close proximity to the mountainside while seeking an updraft.
- The primary cause of the accident was a loss of control due to an aerodynamic stall occurring while the pilot was turning toward an updraft.
- The high load factors (estimated between 2.5 to 3 g's) during the coordinated, aggressive turn increased the stall speed to a level that the aircraft's speed could not sustain, leading to the loss of lift and subsequent impact.