What happened
On April 18, 2003, a Grob G 102 Astir CS 77 glider, registration I-IVBH, was performing a landing circuit at Belluno Airport when it struck the ground approximately 300 meters before the runway threshold. The flight, which had begun earlier that day for a local soaring session, was interrupted during the base turn.
During the approach, the pilot noted a discrepancy between the airspeed indicated by the airspeed indicator and the speed reported by the tow plane, leading the pilot to fly at a higher speed of 110 km/ and instead of the standard 95 km/h. As the pilot executed a right-hand base turn, they became distracted by a pedestrian walking in the intended landing area. While attempting to manage this distraction and simultaneously trying to reduce speed, the pilot inadvertently induced a stall of the right wing. The aircraft entered a steep, nearly vertical descent, and the pilot lost consciousness momentarily. The glider impacted the terrain in a level attitude before sliding into trees, causing extensive structural damage to the airframe and wings.
The investigation
The ANSV examined the aircraft's maintenance records, which showed the glider had undergone a 100-hour inspection shortly before the accident. The investigation also focused on the airspeed indicator; while bench tests showed the instrument was functioning within tolerances, the investigators could not definitively confirm or rule out the presence of an error in the pitot-static system. The pilot's experience and training were also reviewed, noting that recent aerobatic training had helped the pilot react to the unusual attitude before the impact.
Findings
- The primary cause of the accident was the incorrect execution of the base turn, which resulted in an unintentional stall at an altitude insufficient to recover.
- The pilot's attention was diverted by the presence of a person in the landing zone, which was possible due to the lack of airport fencing and signage.
- The pilot continued the flight for several hours despite suspecting an airspeed indicator error, rather than performing a stall test to verify the instrument's accuracy or terminating the flight.
- The lack of perimeter fencing at the airfield allowed unauthorized persons to enter the landing area, creating an unexpected hazard.