Yeh ! got my first half decent boosts yesterday, 12-15 knots with a Flysurfer P4 15m 
Landed several well and rode away, dropped ass first into the water on a couple but the last one had me airborne downwind at speed. Managed to land it but the kite came down in a ball and I spent the next 10min re launching.
Why did the kite fall out of the sky and how do I stop it happening again 
Nice one. Most likely you got your timing wrong at the takeoff and flew downwind towards and under the kite, completely depowering it. Try to hold your edge as long as possible before take off (rather than getting pulled off your edge by the kite), and carve slightly upwind and push off and pop out of the water at the point of takeoff. You'll notice the difference when you get it. Good luck.
Buell,
O is right, if you swing under your kite it will lose all power and hindenburg on you. If you find you're following O's advice and it's still happening, try turning the kite to send it back to the horizon a little sooner. This is also less likely to happen the more win you get.
D
has any one got any advice on how to avoid coming back into landings going too fast. , i take off either boosting or just jumping and find quite often that the speed on landing is just way too quick
!!!!
spot your landing,head further down wind once you land, hang on and slowly get your edge back bringing the kite back to the front of the window while controlling your excess speed. Main thing is to keep your cool. This is what i do anyway, works every time, whether its right or not is another thing. 
!!!!
I managed to swing under a 15m FS the first time I tried one, it's easy to do. It's also easy to recover from without wetting the kite, just steer the crap out of it as you swing under it. Even if you crash-land the kite won't.
as you start your decent you need to pull your front hand to bring the kite back down. otherwise you overfly the kite and it flies over your head and crashes.. so when coming down bring the kite down too
Thanks Guy's, looks like my last boost yesterday was a combination of just about every mistake, sent the kite from 2 o clock, not much edge, then OH S**T when I got more air than expected.
Spent the air time getting the board positioned for a fast landing and completely forgot to pull down the front hand.
Like the "Hindenburg" effect, is that new terminology specific to crashing foils 
Nah, a Hindenburg is when any kite completely loses lift (as in when it flies forward out of the window during a gust then luff, or you swing under it on a jump).
D
