I wish I had filmed it... hard to believe otherwise. I witnessed, with
several others, the final moments of a commercial ride at an east coast
gliderport. The commercial pilot turned very short base to final and
failed to level out completely before the right wingtip touch the
ground. The glider rotated 180 degrees in the air, the landed (pretty
smoothly) backwards. It tracked straight for several wingspans, then
touched a wingtip and ground looped 180, once again facing its
direction of travel. The passenger got out and exclaimed it was the
coolest flight he'd ever taken.