All you need to do is to wait until the aircraft is about 2 metres or less above the ground then step out. Most people are capable of surviving a fall of 2 metres or less..........
You can practice for this by standing on a table on top of a high building and getting somebody to push the table over the side. Just before, or just as the table legs make contact with the ground, step off - et voila! It takes a bit of practice, so perhaps is should be included in annual emergency training??
Sounds like a Viz top tip!!
For those unfamiliar with Viz:-
Viz Comic