Bodyflight in Bedford UK has an actual system to train exits. I haven't tried it myself so I don't know what it is like but from the description it seems okay.
It is a rope jump, but I don't think a heli is involved. I think they run the rope from the exit platform down to the ground over to another elevated object with a lot of slack in the rope. So.. when the person jumps they just drop until meet up with the slack at the bottom of the jump. Wild shit. :)