What happened
On July 25, 2002, a Discus B glider, registration D-0410, was participating in the fourth flight task of the Italian Promotion Category Championship at Rieti Airport. The aircraft had taken off via aero-tow at 10:56 UTC, utilizing 120 liters of water ballast in the wingtips to increase its wing loading for higher cruising speeds.
While maneuvering near Colle Alario, approximately 8 km from the airfield, the pilot was attempting to utilize thermal currents near the eastern slope of the mountain. An eyewitness reported that while the glider was in a turn, one wing suddenly dropped sharply, causing the aircraft to enter a steep dive. The glider struck the eastern slope of Colle Alario at an altitude of approximately 1,000 meters. The impact was severe, resulting in the destruction of the aircraft and the death of the pilot.
The investigation
The ANSV investigation examined the wreckage, flight data from a recovered logger, and meteorological conditions. The investigation confirmed that the aircraft's forward fuselage broke into multiple pieces and the left wing detached from the fuselage upon impact.
Analysis of the flight data and wreckage indicated that the aircraft was traveling at an estimated impact speed of 120–130 km/h. The investigation focused on the aerodynamic state of the glider immediately prior to the loss of control. Investigators also reviewed the pilot's experience and the regulatory requirements for license reinstatement in Italy at the time of the event.
Findings
- The primary cause of the accident was an aerodynamic stall occurring during a turn.
- Irregular thermal currents likely increased the angle of attack on the left wing, triggering the stall.
- The pilot may have tightened the turn to stay within the thermal or to maintain separation from the terrain, reducing the safety margin between the flight speed and the stall speed.
- A momentary decrease in the pilot's situational awareness or attention level contributed to the inability to recover from the sudden wing drop.
- Due to the suddenness of the event and the proximity to the terrain, the pilot had insufficient time to execute recovery maneuvers.