What happened
On 17 August 2023, two gliders, a Ventus-2CT (G-KADS) and an E1 Antares (G-CLXG), were participating in a gliding competition at Husbands Bosworth. While maneuvering within a thermal south of Melton Mowbray, the two aircraft entered a flight path conflict.
As the pilot of G-KADS initiated a fourth turn in the thermal, they increased the angle of bank, which increased the turn rate. Simultaneously, the pilot of G-CLXG began reducing their bank angle to exit the thermal. This maneuver caused G-KADS to turn inside the path of G-CLXG. The right wing of G-CLXG struck the tail section of G-KADS, severing it.
The loss of the tail caused G-KADS to descend uncontrollably, striking the ground at high speed. The pilot of G-KADS sustained one fatality. The pilot of G-CLXG was able to land the damaged aircraft safely in a nearby field and was uninjured.
The investigation
The AAIB examined the wreckage of both aircraft and analyzed flight data. The investigation found that the geometry of the aircraft positions placed both gliders in each other's blind spots; G-KADS was positioned behind and slightly above G-CLXG, while G-CLXG was below the field of view of the G-KADS pilot. Additionally, the sun's position likely made the other aircraft harder to spot.
Both aircraft were equipped with FLARM electronic collision warning systems. While the systems were functional and had detected the proximity of the other aircraft, the investigation noted that the pilot of G-CLXG had the alert threshold set to a level that might not have prioritized the warning. The investigation also noted that the aircraft were white and lacked high-contrast markings or strobe lights, which could have hindered visual acquisition.
Findings
- The collision occurred because G-KADS turned inside the path of G-CLXG, reducing the separation between the two aircraft.
- The aircraft were positioned in each other's visual blind spots at the time of impact.
- The use of a thermal with multiple aircraft increased the complexity of the maneuvering.
- The lack of external anti-collision lighting or high-contrast paintwork may have made the aircraft more difficult to identify visually.
Safety action
- The British Gliding Association (BGA) has updated its website guidance regarding managing flying risks during competitions.
- The BGA is launching a midair collision safety campaign in early 2024.
- The BGA is evaluating a proximity monitoring tool to identify close encounters in flight logs for use in safety debriefs.