DG-800 motor go-around attempt at 20 m AGL — collision with treetops

A DG Flugzeugbau DG-800 self-launcher from Issoire - Le Broc (LFHA) struck treetops short of an outlanding field; the pilot was uninjured and the glider substantially damaged. Conditions were worse than forecast. After unsuccessful lift in a valley, the pilot picked an outlanding field at <100 m AGL. On base-to-final at ~20 m AGL he deployed the propeller intending to motor away — his habitual technique, with the field landing as fallback. Eight seconds later, motor not yet running and sink increased by the extended propeller, the glider struck 20 m treetops. BEA cited the late deployment, below the 400 m flight-manual minimum.

1. Local soaring from Le Broc: The pilot self-launched at 11:49 from Issoire - Le Broc (LFHA) for local soaring. After ~1 h 15 min thermalling and a max altitude of 1580 m, he entered a valley southwest of the airfield in search of lift.
2. Unfavourable aerology: Forecast conditions were better than what the pilot encountered: low ceiling, weak and hard-to-detect thermals. After 10 minutes of unsuccessful lift attempts in the valley, the glider was down to ~611 m altitude (<100 m AGL per BEA footnote).
3. Habitual motor go-around: Per the pilot's own statement, his customary technique was to deploy the propeller only when established on an outlanding circuit, then start the motor on final to climb away 'like a go-around', with the field landing as a fallback if the motor wouldn't start.
4. Propeller deployed at ~20 m AGL: After committing to an outlanding circuit and turning onto final, at ~20 m AGL above the chosen field the pilot deployed the retractable propeller. The DG-800 flight manual requires this be done at minimum 400 m AGL near a suitable landing zone, or 1000 m otherwise.
5. Sink rises, motor not started: The flight manual states that with the propeller extended and motor not yet running, sink rate at 90 km/h increases by ~2 m/s (~400 ft/min). The deployment sequence takes about 10 seconds.
6. Collision with 20 m treetops: 8 seconds after deployment began, with the motor not yet running, the glider in level flight struck the tops of 20 m trees upstream of the chosen field and came to rest at the field edge. Right wing torn off, fin broken, canopy shattered. Propeller pylon found extended and locked; propeller blades damaged with no rotation marks. Substantial damage; pilot uninjured.