Accident to the glider Jonker JS1 registered ZS-GDE on 15/07/2022 at Château-Arnoux - Saint-Auban

The glider was on the final approach path with an average slope of 13 % to land on runway 20 at Château-Arnoux - Saint-Auban aerodrome. On final at a height of around 65 m, the glide slope increased sharply to 24 % before stabilising again at around 10 %. The glider, which was low and below the approach path, collided with the top of the trees about 15 seconds later. 

It is possible that an aerological phenomenon caused ZS-GDE to lose altitude on short final. Indeed, the weather conditions on the day of the accident, combined with the particular geographical environment to the north of the aerodrome, were conducive to the occurrence of turbulence and wind shears near the ground. The paths of the other gliders on final shortly before the accident were normal, so this phenomenon probably appeared suddenly and locally. It may have caused a sudden drop in the glider’s true airspeed and angle of attack, resulting in a marked reduction in lift and a rapid loss of altitude. As the use of air brakes has little effect on speed, their retraction by the pilot did not reduce the rate of descent.