What happened
On July 9, 2005, a private Schleicher ASW 20 glider, registration EC-ICP, was performing a recreational flight near Monflorite, Huesca. After being towed from Monflorite Aerodrome earlier in the afternoon, the pilot was conducting a high-speed final glide toward the base. While flying at approximately 200 km//h, the aircraft encountered a powerful vertical gust and significant turbulence.
This sudden atmospheric change, combined with a shift in wind direction from a tailwind to a headwind, caused the aircraft to experience intense vibrations. The pilot attempted to pull back on the control column to prevent a dive, but the aircraft entered an uncontrolled descent. During the struggle to maintain control, the pilot released the harness and was ejected from the cockpit, striking the canopy with his head before deploying his parachute. The glider continued to descend in a steep dive, reaching speeds of approximately 270 km/h, before impacting the ground in an inverted position. The pilot landed approximately 400 meters away from the wreckage, suffering broken ribs and other injuries.
The investigation
CIAIAC investigators examined the wreckage and flight data recorded by the aircraft's onboard logger. The inspection of the EC-ICP revealed significant structural damage, including a broken left wing and various cracks and fissures on both wing surfaces. These cracks were attributed to extreme wing flexing during the flight.
The investigation also analyzed the meteorological conditions, noting that while no thunderstorms were present, high surface temperatures likely generated moderate thermal activity and turbulence. The flight logger confirmed that the aircraft was flying at 200 km/h, which exceeded the manufacturer's recommended speed limit for turbulent air (VB = 180 km/h). The investigation also considered the possibility of aeroelastic phenomena, such as aileron flutter and control reversal, which may have been triggered by the structural loss of stiffness.
Findings
- The aircraft was flying at 200 km/h, exceeding the maximum permissible speed for turbulent air (180 km/h).
- The aircraft encountered severe vertical gusts and turbulence, which included a significant wind shear effect as the wind direction shifted.
- The pilot's attempt to recover the aircraft via abrupt control inputs likely added aerodynamic loads that, when combined with the gust loads, exceeded the structural limits of the airframe.
- The resulting structural deformations and cracks led to a loss of torsional stiffness, potentially inducing aileron flutter and control reversal.
- The pilot's exit from the aircraft occurred without first opening the canopy, leading to head injuries upon impact with the cockpit structure.