A disaster - or gap to rail - means skipping the first half of a kinked rail and landing on the last section instead. Rather than boardsliding a down-flat-down all the way through and absorbing every pitch change, you air over the kink and touch down past it on one straight piece.
It's a speed trick. Take more than you'd normally use on that rail, because landing short - directly on the kink - kills all your momentum at once and puts you on the ground. Build up to it by airing over the side of the rail a few times: same run in, same pop, but you land on snow next to it. Once you're clearing the kink every time, move your line over and put the board down in a 50-50 on that last section.
The landing is the easy half. There are no kinks left to upset you, so it's really just a straight air that happens to finish on metal.
Watch more here at the 4:21 mark:
Video by Ed Shreds