Discus b ridge-flight collision; probable sudden incapacitation

On 31 May 2009 the pilot of a Discus b died in a near-vertical impact on a slope near Gryon during a ridge flight; the aircraft was destroyed. Newly transitioned to the type, he had launched at 13:04 from Bex by aerotow and released NW of the Col de la Croix. After ~45 min on the local ridges, witnesses saw the glider continuing its turn against the slope with increasing bank and pitch-down, without any recovery attempt, until it struck the ground almost vertically. No technical defects were identified; the probable cause was sudden in-flight incapacitation against pre-existing chronic illness undeclared to the AME.

1. Aerotow Bex; release NW Col de la Croix: At 13:04 LT the Discus b launches on aerotow from Bex in second position; the pilot releases about ten minutes later NW of the Col de la Croix and flies ridge soaring in the Leysin – Villars-sur-Ollon – Gryon area.
2. Low experience on type: The pilot has held a glider licence for about a year. Total glider time is about 60 hours; the time on the Discus b is about 1 h 29 min in three transition flights logged by an instructor — this is his first solo on type outside the aerodrome circuit.
3. Witnesses: unusual flight path: After about 45 minutes of ridge soaring the glider is noticed by model-aircraft enthusiasts at Les Frasses, southeast of Villars-sur-Ollon. One witness reports an unusual whistling sound; another sees the glider continuing to turn without any apparent attempt to level off.
4. Turn against slope, no recovery: The glider continues its turn back into the hillside, with progressively increasing bank and an ever-steeper nose-down attitude. No recovery input is observed. The final three-quarter turn ends with the glider almost vertical.
5. Near-vertical impact in pasture: The Discus b impacts a pasture near Gryon almost vertically. The cockpit penetrates the soft topsoil; the leading edges of the wings stop the fuselage from going further in, and the fuselage breaks about 50 cm aft of the wing trailing edge. The aircraft is destroyed and the pilot is fatally injured.
6. Probable incapacitation; undeclared: Examination finds no pre-existing technical defects. Mass and centre of gravity are within limits; partially extended airbrakes are attributable to the impact. The pilot held a valid Class 2 medical, but he had not reported a pre-existing chronic illness or a recent significant operation to the aviation medical examiner — disclosures that would have led to a finding of unfitness. Impact damage prevented forensic confirmation, but the witnessed flight path and medical background together point to a sudden in-flight incapacitation as the most probable cause of the loss of control.