Hello Tom,
That was one nasty accident and witnessed by so many other riders too. Do you remember the date and approximate time of the accident? I have a favor to ask, could you rig the QR incorrectly and correctly and take photos of each setup and send them to me? I would like to post the images here.
I am very happy your lofting had a good ending. With something as large as an 18 m up in the face of such winds there is no assurance that someone even will survive. I am reminded of a fatality last year in Okinawa. A rider was out, a squall moved in from a feeder band related to a typhoon (Pacific hurricane) a distance away. He "tried" to get in to land, perhaps to have someone catch his kite instead of immediately totally depowering his kite where he was. Anyway, he never made it that far. He was lofted at high speed out of the shallows landward toward a concrete wall. He hit it and died. Prior to the lofting he was seen to be furiously pulling on his quick release that failed to open.
It was reportedly an OLD side release snapshackle incorporated into his control bar by one of the major manufacturers a few years back.
NO ONE SHOULD BE USING ONE OF THESE SHACKLES FOR KITEBOARDING. They fail to release if they are overloaded, if the release is pulled out of a conical area, if they are fouled ... too many reasons why they won't release. Checkout your gear and that of others you see to make sure they aren't using some of this old, deadly crap.