G 103 C / ASK 18 mid-air in shared thermal — FLARM alerts not heeded

All three occupants bailed out with minor injuries when a Grob G 103 C and a student-flown ASK 18 collided while thermalling near Utscheid; the G 103 C was destroyed and the ASK 18 substantially damaged. After the shared circle's centre shifted, the G 103 C lost sight of the ASK 18, tightened toward the new centre, and closed from behind outside the student's field of view. The G 103 C's left wing destroyed the ASK 18's canopy. Both carried FLARM, but the alerts were not heeded.

1. Aerotow — thermaling: After aerotow departures from Segelflugplatz Utscheid, the G 103 C with a passenger and the ASK 18 student glider climbed and began thermaling in the same area in blue thermals.
2. Mixed-experience gaggle: An experienced G 103 C pilot and a low-time ASK 18 student flew close together in the same thermal, requiring strict mutual visual lookout and coordination.
3. FLARM warnings unused: Although both gliders were equipped with functioning FLARM collision warning devices, their optical and acoustic alerts were not heeded by the pilots.
4. Loss of visual contact: After the shared thermal circle shifted, the G 103 C pilot lost sight of the ASK 18 and the G 103 C moved into a position outside the ASK 18 pilot’s field of view.
5. Converging in same thermal: During a shift of the common circling center, the G 103 C tightened toward the new circle center and closed from behind on the ASK 18 at similar altitude.
6. Mid-air collision: At about 1,200 m above ground southwest of Utscheid, the left wing of the G 103 C struck and destroyed the canopy area of the ASK 18, severing part of the G 103 C’s left wing.
7. Crash - minor injury: All three occupants bailed out under parachutes with minor injuries; the G 103 C was destroyed and the ASK 18 severely damaged, wreckage coming to rest in fields near Utscheid.