LS6 hits treetops with airbrakes likely deployed throughout flight

An LS6 18w struck treetops on a clearing approach ~14 km NW of Fayence; the pilot was uninjured and the aircraft substantially damaged. The pilot, aiming for a 750 km flight, released from aerotow at ~1,930 m near Mt Lachens. Descent rates of -6.8, -7, then -9.3 m/s matched the glider with airbrakes and gear out (L/D ~7 vs 48). The pilot blamed the air, did not check the brakes, and continued past La Chapelle until running out of height. Inspection found a 15 cm branch in the right airbrake slot and the handle in 'closed unlocked' — on the LS6 an unlocked handle self-deploys the brakes. BEA cited the undetected airbrake deployment.

1. Aerotow toward Mt Lachens west face: Local mountain-soaring flight from Fayence (Var), runway 10L. Aerotow behind a Piper PA-25 Pawnee 235 hp; climb rate normal at ~3 m/s. Pilot 74 yo, SPL since 2003 (instructor rating 2015, not actively instructing since 2022), ~2,200 h total / ~1,870 PIC / 23 h on type in last 3 months. Familiar with Fayence and mountain flying; had flown two ≥5 h cross-country trips with this glider in the preceding two weeks. Pilot was 'agitated and determined' to do a long flight (per club-mate observations). Weather: S/SE to S/SW wind 5-10 kt (gusts 15 kt), CAVOK, light-moderate low-level turbulence south of accident site.
2. Goal: 750 km flight: Pilot's planned task was a 750 km cross-country if conditions allowed. Sets the context for the decisions to continue past degraded performance. BEA contributing factor.
3. Unlocked airbrakes deploy in flight: Release at ~1,930 m near the west face of Mt Lachens at 10:55:19. On the LS6 18w, the airbrake handle must be shifted right and pulled with effort to unlock; if left unlocked (not held), shared pilot experience reported that the airbrakes self-deploy in flight. Post-accident the handle was found in 'closed not locked' position, and a ~15 cm branch was jammed in the right airbrake slot — strongly indicating the airbrakes were deployed during flight (whether due to lock failure, mis-locking missed at preflight, or unintended pilot action — BEA could not determine which).
4. Immediate sink -6.8, then -9.3 m/s: Sink rates and groundspeeds recorded by FLARM: -6.8 m/s immediately after release; -7 m/s at 120 km/h crossing the ridge; -9.3 m/s at 130 km/h crossing the south face of a second relief. These values match the LS6 with airbrakes AND gear extended (L/D ~7 vs the type's max L/D of 48 — a ~85% performance loss).
5. Sink misattributed to weather: Pilot stated he attributed the descent rate to poor aerology (conditions he later called 'absurd'). He looked outside regularly but reported nothing unusual and explicitly did not check the airbrake handle or wings, despite the extreme sink rates. BEA safety lesson: a sudden degradation of sink rate is not always external — it can be the result of a pilot action (deliberate or not).
6. Skipped La Chapelle safety landing: At point 3 of the track, the pilot was 460 m above the La Chapelle listed safety landing area (in the 'Guide des aires de sécurité dans les Alpes') and ~2,000 m horizontal — within glide even at the degraded L/D of 7. He chose instead to continue toward the Vallon du Fil, hoping to find thermals. BEA safety lesson: when degraded performance persists, choosing to land on a known safety area is an option not to neglect; pilot experience can lead to overconfidence in incomplete decision-making.
7. Out of glide range, low in valley: By the time the pilot decided to leave the relief and head for the valley, sink had stabilised at ~2.5 m/s while airspeed kept decreasing. He was no longer within range of a prepared safety landing area; at 25 m AGL he spotted a small clearing to the right of his track and elected to outland there.
8. Treetop strike, hard landing: At ~85 km/h groundspeed and ~50 m before the clearing, the glider struck treetops bordering the clearing in the Vallon du Fil, then impacted the ground hard. Pilot uninjured and self-evacuated; aircraft substantially damaged (fuselage broken, elevator control heavily damaged). The accident site is 14 km NW of Fayence.