Le vendredi 7 septembre 2018 02:55:44 UTC+2, Roy B. a écritÂ*:

Think of Helmut Reichman, Klaus Holighaus , Bill Ivans and many other masters of our sport that are gone. Did they have a "demonstrable lack of knowledge"?

Interstingly, three completely different accidents, by the way:
Reichmann: collision with another glider
Holighaus: collision with a mountain side
Ivans: loss of control at high altitude and break-up in mid-air