Hola all.
Had my first ever flat spin yesterday, enduced by someone swinging me upon letting go in a chest strap hanging rodeo. (I think it can be done but preferably with someone lighter than my bro...)
Anyway, the reason I'm posting is to share a simple recovery technique - I tried to dive out, didn't feel much change, tried streching my leg wing to no avail, whilst I did not try balling up the approach I used stopped a VERY fast spin in a very short period of time - I've seen some videos of flat spins such as this - http://www.youtube.com/watch?v=8L0-y4x2KQM where it looks very 'verticle barrel roll' like - I'm not sure if my approach will work on these but if the spin is truely flat (you are face to earth the whole time) using the FS style 'side slide' technique of digging a knee in with an elbow (And thus cupping air against the direction of the spin using the arm wing, really catching the air with the wing, I'm not sure if the knee was actually doing much as the arm was definitely slowing it down most but it just felt natural) worked very quickly.
I'm sorry if that seems like an obvious approach but I've not ever heard or read of anyone saying about this approach (it always seems to be ball up, arch or dive) and it worked better for me than arching/diving attemps (though I can't comment on the balling up though I imagine it'd be very hard to do at such speed of rotation).
Safe jumping all!