Why low passes? Well, to have fun, of course, but also because, according to some, going into ground effect some distance before the arrival line is the most efficient way to finish a competition flight.

However, according to most "mathematical minds", the energy loss incurred by having to accelerate to VNe and keep the speed at VNe until going into ground effect, can never be compensated by that ground effect. Certainly not if you still have enough energy when crossing the arrival line to pull up and do a 360 before landing. That energy is lost for the flight. You can just have fun with it, if it doesn't scare you to death - or kills you.

Some years ago (2003-2004, IIRC), the British Juniors published a series of "smoking vid" DVD's that were sold as a fundraising source for them and showed some of the most crazy low passes you can imagine. I even seem to remember a low pass by an Astir CS where the belly of the glider actually touched the ground at full speed, going straight at the camera. Sure, it was fun....

But then, at the Junior World Gliding Championships at Husbands Bosworth, Leics, in August 2005, Neil Lawson, a well known glider photographer, was killed by the low passing glider he was photographing. No more "smoking vids" after that event. And the championship rules where amended to actively discourage low pass arrivals.