What happened
On August 9, 2022, during the 12th FAI Junior World Gliding Championships near Staré Sedlo, Czech Republic, two gliders collided while maneuvering within a thermal. The first aircraft, an LS8-18 with registration G-XWON (operating under callsign 1X), was performing a right-hand turn following a teammate. The second aircraft, an LS4-A with registration HB-3025 (operating under callsign CR), attempted to merge into the thermal between two other circling gliders.
As the pilot of the LS4-A initiated a right turn to join the formation, the aircraft's flight path intersected with the G-XWON. The left wing of the G-XWON struck the upper part of the cockpit canopy of the HB-3025. The impact shattered the canopy and caused the LS4-A to roll and enter a steep descent. Due to the intensity of the impact and the loss of canopy integrity, the pilot of the HB-3025 executed an emergency parachute deployment, landing approximately 1.7 km from the impact site. The LS4-A subsequently crashed into a forested area. The pilot of the G-XWON maintained control of the aircraft after the collision and performed a successful landing in a field near Láz.
The investigation
The ÚZPLN investigation examined the flight trajectories, meteorological conditions, and pilot testimonies. The commission reconstructed the collision using glider models and analyzed cockpit video footage. The investigation confirmed that both pilots were properly qualified, medically fit, and that both aircraft were airworthy and compliant with competition technical requirements. The investigation also reviewed the functionality of the FLARM collision avoidance systems, noting that while the systems were operational, the pilots did not identify the imminent threat in time.
Findings
- The collision occurred because the pilot of the HB-3025 misjudged the closing distance and the relative positions of the aircraft in the thermal.
- The pilot of the HB-3025 intended to join the formation between two existing gliders but failed to recognize that the G-XWON was approaching from a spiral path on a nearly identical altitude.
- The pilot of the G-XWON identified the HB-3025 initially but lost visual contact due to the HB-3025's banking maneuver.
- The pilot of the HB-3025 failed to maintain a safe separation distance during the merging maneuver.
- The presence of multiple gliders in the immediate vicinity likely contributed to the pilots' divided attention, preventing the timely detection of the collision risk despite functional FLARM alerts.