Skilful use of headwind and thermal updrafts along various sections of the hill is used to generate additional lift, creating pressure under the oversized skis and enabling athletes to effectively ride on a 'cushion of air'. Mastering the wind conditions is an overwhelmingly important part of ski flying. A reasonable amount of headwind is favourable to a long jump as it has the effect of keeping the athlete aloft and delaying their descent back onto the hill. Conversely, despite providing somewhat of a boost in speed, a tailwind is unfavourable and tends to shorten a jump by pushing the athlete downwards towards the hill prematurely. Even more unfavourable are 'dead' conditions – or no wind at all – which can cause the air pressure to vanish unexpectedly in mid-jump and force the athlete to fall from a dangerous height.