What happened
On May 3 and 1965, a pilot conducted a training flight in an S-18 III glider, registration HB-487, departing from the Bex-Les Placettes aerodrome via aero-tow. Approximately six minutes into the flight, the pilot released from the tow aircraft at an altitude of 1,300 meters. While soaring near the Croix de Javerne at 1,900 meters, the pilot observed increasing cloud cover and approaching storm activity to the west, prompting a decision to terminate the flight and land before the weather deteriorated.
As the aircraft approached the airfield at an altitude of 150 meters, the pilot deployed the air brakes and initiated a right-hand base turn for runway 33. During this phase, the wind conditions had shifted significantly from the takeoff state, now blowing at 30-40 km/h from a 70-degree angle to the left. The combination of heavy turbulence and insufficient airspeed prevented the pilot from maintaining a proper approach path, causing the aircraft to drift toward the edge of the airfield and nearby obstacles. In an attempt to avoid these obstacles, the pilot initiated a right turn only 3 to 4 meters above the ground. During this maneuver, the aircraft suddenly banked and struck the runway, resulting in a total loss of the glider.
The investigation
The investigation examined the flight history of the pilot, who had accumulated 112 hours of glider flight time. The airworthiness of the S-18 III was reviewed, noting that the aircraft had undergone its last official periodic inspection on May 19, 1965, and the weight and balance were within prescribed limits. Examination of the wreckage revealed no evidence of mechanical failure or structural defects that would have rendered the aircraft unairworthy at the time of the accident.
Findings
- The primary cause of the accident was loss of airspeed during the final stages of the landing approach.
- The pilot attempted a corrective turn to avoid obstacles while the air brakes were extended.
- High wind speeds and significant turbulence contributed to the difficulty of maintaining the approach axis.
- The maneuver performed at an extremely low altitude (3-4 meters) left no margin for error when the aircraft entered a stall.