What happened
On June 30, 2018, a Northrop F-5E Tiger, registration J-3088, acting as the leader of the Patrouille Suisse aerobatic team, was performing a flight display near the Fricktal-Schupfart airfield. Simultaneously, a Schempp-Hirth Ventus 2c glider, registration D-4363, was conducting a cross-country flight through the region.
As the military formation was executing a high-speed maneuver, the leader suddenly sighted the glider positioned directly in the flight path. Due to the significant speed differential—the jet formation traveling approximately seven times faster than the glider—an evasive maneuver was impossible. The aircraft came within a vertical distance of approximately 40 meters and a horizontal distance of roughly 100 meters. The glider pilot reported hearing the jet engines before visually identifying the aircraft, and the encounter was classified as a high-risk near-collision.
The investigation
The investigation examined the airspace restrictions in place at the time, which included temporary restricted areas designed to protect the aerobatic display. Investigators reviewed radio communications, noting that while the glider pilot had monitored the airfield frequency, he did not announce his position or intentions. The investigation also looked into the visibility of the glider to ground controllers and the military operations center. Furthermore, the technical equipment of both aircraft, specifically the use of transponders and tracking systems, was evaluated to determine why the encroachment was not detected earlier.
Findings
Several critical factors contributed to this dangerous encounter:
- The D-4463 glider was not equipped with a transponder, making it invisible to the military operations center and preventing the leader from receiving an early warning.
- The glider pilot failed to communicate his flight path or position on the airfield frequency, which prevented ground coordinators from alerting the formation leader.
- The high speed of the Patrouille Suisse formation meant that even if the glider pilot had spotted the jets earlier, the momentum of the formation made an effective avoidance maneuver impossible.
- While ground observers at the airfield tower reportedly sighted the glider, this information was not successfully relayed to the formation leader in time to alter the flight path.
- The pilot of the glider had not consulted updated aeronautical information regarding the specific airspace restrictions active for the airshow.