SF 25 strikes LS 4 from below on short final

An SF 25 overtook a slower LS 4 from below on short final and clipped its right wing; the SF 25 hit hard at full throttle and rolled into trees, the LS 4 landed normally. No injuries; SF 25 destroyed, LS 4 light damage. Both returned from local flights — the LS 4 in left downwind via Furlepass, the SF 25 in right base — and aimed at the same touchdown point without visual contact; the SF 25 closed from behind and below faster. Multiple go-around calls went unanswered; the SF 25 pilot only heard at 6-8 m AGL and went full throttle as the collision occurred. Findings: both pilots failed to spot the converging approach; SF 25 reacted too late.

1. Both returning to Hornberg runway 18: Two aircraft, an LS 4 and an SF 25 Motorsegler, returned to Hornberg for landing on runway 18 in good VFR conditions: the SF 25 entered right base while the LS 4 entered left downwind.
2. Joined final from opposite sides, no VC: Both aircraft turned final from opposite pattern sides — LS 4 from the left, SF 25 from the right — without visual contact, both aimed at the same touchdown point near the threshold.
3. SF 25 overtaking from behind and below: On final the LS 4 was ahead and slightly higher while the faster SF 25 closed from behind and below; neither pilot could see the other aircraft from his approach attitude.
4. Unanswered go-around calls: Ground radio calls to the SF 25 — turn right, go around — went unanswered; the SF 25 pilot later said he heard the call only at 6-8 m AGL, too late to react.
5. Fin-to-wing strike; SF 25 into trees: At about 15 m AGL the SF 25 accelerated under the LS 4, its fin striking the LS 4's wing, then crashed into the forest destroyed; the LS 4 landed safely with light damage, no injuries.