What happened
On July 13, 2006, at approximately 14:30 local time, a Blanik L13 glider, registration EC-CIV, was performing a recreational flight at the Santo Tomé del Puerto aerodrome in Segovia, Spain. The flight, which began via aero-tow, lasted approximately 15 minutes. After finding no rising air currents, the pilot decided to land on runway 12.
During the landing pattern, the aircraft was on final approach at an altitude of approximately 150 meters. While executing the turn to final, the left wing of the glider struck a holm oak tree located near the runway threshold and to the left of the centerline. The impact caused the aircraft to yaw left by more than 90 degrees, dropping from an altitude of approximately 2 meters before impacting the ground. The aircraft sustained significant damage, including a hole in the leading edge of the left wing and structural deformation to the fuselage.
The investigation
The investigation examined the flight path, the pilot's experience, and the environmental conditions at the aerodrome. The investigation established that while the pilot was experienced in gliders, his total flight time was relatively low (220 hours), and his experience specifically with this runway configuration was limited, as most operations at the aerodrome utilize runway 30.
Investigators analyzed the aircraft's descent profile and the use of air brakes. Evidence suggested that the pilot may have deployed the air brakes for an extended period during the descent. Additionally, the investigation looked into the aircraft's alignment with the runway centerline during the turn to final, noting that the pilot had been actively using rudder pedals to correct the trajectory.
Findings
- The primary cause of the accident was an encountered downdraft that increased the descent gradient, preventing the aircraft from reaching the runway threshold.
- The pilot's lack of familiarity with the specific approach procedures for runway 12, which is rarely used, contributed to the difficulty in maintaining the correct glide path.
- The extended use of air brakes during the descent likely contributed to the steepening of the descent angle.
- The pilot's attention was divided by the need to correct the aircraft's lateral position relative to the runway centerline during the turn to final.