What happened
On April 26, 2002, an Alexander Schleicher ASH-25 glider, registration D-5415, was engaged in a cross-country flight originating from Asiago Airport. The flight plan involved a 500-kilometer route passing over Belluno and Osoppo. The crew consisted of two experienced pilots, with the more senior pilot seated in the front and a second pilot in the rear.
While navigating the Alpago basin to locate rising air currents, the glider entered a 360-degree left-hand spiral to remain within a thermal. During this maneuver, the aircraft was approximately 60 meters away from a rocky ridge. Suddenly, the glider encountered a pocket of turbulent, descending air. This sudden loss of lift caused the left wing to stall. Due to the extremely low altitude, the pilot was unable to recover control within the two to three seconds preceding the impact. The aircraft struck the ridge with its left wing, followed by the fuselage and the right wing, resulting in the total destruction of the aircraft.
The investigation
The investigation relied heavily on the testimony of the surviving pilot. Investigators examined the meteorological conditions reported by an emergency helicopter crew that arrived at the scene approximately 16 minutes after the accident. The weather was characterized by good visibility but included strong winds and significant downdrafts within the canyon, with cumuliform clouds positioned just above the ridge.
Findings
- The primary cause of the accident was a left-wing stall triggered by sudden descending air currents.
- The proximity to the terrain prevented any possibility of aerodynamic recovery.
- The investigation noted that the flight conduct may have been imprudent, likely due to an overestimation of pilot capabilities and an inadequate assessment of the local orographic and meteorological conditions.