What happened
On May 28, 2017, a pilot was conducting a cross-country flight in a Rolladen-Schneider LS 6-c18 glider, registration HB-3210, departing from Thun Airport. While navigating the Bernese Oberland region, the pilot entered a thermal updraft near the Winteregg ridge. During a right-hand circling maneuver, the pilot observed a golden eagle also circling in the same updraft. While the flight paths initially appeared to be non-threatening, the eagle abruptly changed direction toward the aircraft.
At an altitude of 2,920 meters, the eagle struck the right side of the cockpit canopy, causing it to burst. The impact was so forceful that the bird became momentarily lodged in the cockpit above the pilot's headrest, requiring the pilot to manually remove the animal. A secondary loud noise and a slight leftward drift of the aircraft suggested further damage, which was later identified as an additional crack spanning the entire canopy. Despite the structural damage and debris in the cockpit, the pilot maintained control and proceeded directly back to Thun Airport for a safe landing.
The investigation
The investigation focused on the sequence of events leading to the impact and the behavior of the wildlife involved. Investigators examined the flight path, the structural damage to the HB-3210, and the nature of the collision. The examination revealed that the right side of the canopy was missing, a large crack had formed across the remaining structure, and the pilot's seatback was broken in several places. The pilot sustained light injuries during the incident.
Findings
- The collision was caused by the sudden aggressive maneuver of a golden eagle toward the glider.
- The eagle likely perceived the glider as a competing flying species due to its silhouette and speed.
- It is believed that once the aircraft closed within a critical distance of approximately 100 meters, the bird's territorial instincts triggered an instinctive attack.
- The pilot's decision to return immediately to the airfield was appropriate given the compromised structural integrity of the canopy.