below a wipe-study which confirms my statement that maybe 50 km/h is the critical mark:

Watch the numbers on the display!
On the first run I am just above that mark (51 km/h) and hit a sandbank. But I manage not to fall. On the second run its below 50 = wipe-out.

But there is still a second reason: I just checked the lines in my evaluation program and found out that shortly before the near-wipe-out resp. the wipe-out I had changed the course to 20 degrees less downwind in order to slow down. So the angle of attack for the fin was too big - the sand came too far from the side.

Third reason: As well in order to slow down I put the kite higher, so it had not enough power to pull me through the sand.

Very interesting the end of the clip: Although I am still sitting on the sandbank for a while the display still shows 30 km/h. After that the display shows 8.67 km/h. And finally one second later 0.50 km/h. So the GPS has a delay of up to 3 seconds compared to the pic ! Keep this in mind when you check your topspeed-pic. This is NOT your topspeed-pic. It has happened two or three seconds before !