I heard about a serious accident today. It involved an experienced kiter solo launching a 15 m flat kite in about 18 mph. He reportedly bent and anchored wing tip with sand in the fashion of C Kites. Another kiter ran over to help him with an assisted launch but arrived just after the kite had been launched.
One of the bridles had wrapped a wing tip sending the kite into uncontrolled looping pulling the kiter at speed inland. The kiter hit a pile of stacked beach chairs breaking one and hitting his head. The other kiter sprinted and secured the kite before the rider could be dragged further. The rider suffered a large bump on his skull and perhaps no other injury. There was no helmet or impact vest in use.
I recently solo launched a 16 m flat kite in light winds in my normal fashion. This consists of leaving the kite leading edge down and pretending that it is being relaunched from water. I have never had incidents prior to this time although I never do this in higher winds. One of the bridles wrapped a wing tip sending the kite into a very slow loop. Despite this I was still dragged about 20 ft. on my feet through the sand. The wind was LIGHT fortunately.
As a rule if a wing tip is wrapped the obvious approach is to drop your bar, pop your chicken loop quick release and set the kite free. Otherwise you will likely be dragged uncontrollably downwind with disabled depowering. I have heard some say to pull in very hard on the leading edge leader lines. I have never tried this and can't comment on this approach.
I am not sure if all flat kites are equally at risk of accidental wrapping of a kite wing tip during solo launch or not. They all have bridles though so it might be best to assume that they all could wrap on solo launch using the two methods described above.
This leaves anchoring the chicken loop, setting the kite up for launching in an upright position and running back to launch it. Not all kites sit nicely in this position and there are other things that can go wrong with this approach.
It seems that competent assisted launches with flat kites are a very good idea and solo launch might unexpectedly result in serious injury over time.
Note: by "flat kites" I am trying to described the various bridled leading edge inflatable kites available today and not kites that are merely "flat" like foils. The dynamics of foil launching are completely different.