What happened
On April 20, 2002, a Schleicher ASW-20 glider, registration EC-EOP, was conducting a training flight near the La Iglesuela aerodrome in the Tiétar Valley. The pilot, a flight instructor with over 400 flight hours, had traveled to the area to take advantage of favorable soaring conditions along the southern slopes of the Gredos mountains.
After being towed to an altitude of approximately 1,000 meters, the pilot began a series of maneuvers to locate thermal currents. During the final stages of the flight, the aircraft performed several turns at low altitude and low airspeed, a common practice when searching for lift at the maximum glide speed. While maneuvering near the terrain, the aircraft entered a stall with insufficient altitude to execute a recovery maneuver. The glider impacted the ground at the "Cerro del Cuervo" site in the municipality of Casavieja, resulting in the death of the pilot and the total destruction of the aircraft.
The investigation
The CIAIAC investigation examined flight data recorded by the aircraft's data logger, which provided a precise reconstruction of the flight path and performance. The analysis of the telemetry showed that in the final thirty seconds of flight, the aircraft was flying at an altitude of less than 100 meters above the ground.
In the final ten seconds, the data revealed a significant increase in the rate of descent—rising from -3.0 m/s to -7.2 m/s—while the groundspeed decreased. The investigation also reviewed the aircraft's maintenance records, which were found to be up to date, and performed an autopsy, which ruled out physiological factors or incapacitation of the pilot. The physical wreckage, which included broken wings and a separated tail section, was consistent with a high-angle, nose-down impact.
Findings
- The primary cause of the accident was the entry into a stall during low-altitude maneuvering, which left the pilot with no margin of altitude to recover.
- The pilot was actively searching for thermal lift, which led to flying at the aircraft's minimum sink speed and performing tight turns near the terrain.
- There were no mechanical failures or malfunctions detected in the aircraft's systems or structure prior to the impact.
- Meteorological conditions were favorable for VFR flight, with clear skies and good visibility.