Accident to the Rolladen Schneider LS4 registered F-CLMF on 25/06/2021 at Vinon-sur-Verdon

The lift-to-drag ratio of the glider observed after the search for uplifts was compatible with that of a glider of the same type with the air brakes fully extended. In addition, the information gathered did not reveal any aerological phenomenon that could explain the continuous high rate of descent of the glider. The most likely explanation was therefore the pilot confusing the controls.

After the cable release, when he wanted to retract the landing gear, the pilot very likely operated the air brake control instead of the landing gear control.

He thus positioned the air brake control aftward in the “air brakes extended” position. Observing an unusually high rate of descent, he supposed that the glider had entered a descending air mass. He focused on the marked deterioration of the glider’s performance and did not check the position of the two levers, nor that of the air brakes on the upper surface of the wings.

Due to the high rate of descent caused by the position of the air brakes and the little amount of time he had to analyse the situation, the pilot did not realise that the glider’s unusual rate of descent could be linked to an incorrect configuration of the air brakes and he did not have the capacity to question his analysis of the situation. He was not able to return to the aerodrome and had no choice but to make a forced landing.