It is recorded that someone has survived a free-fall from an airplane by being lucky enough to land on snow-laden fir trees. My challenge is this: Create a mathematical model which describes the forces at play in order to determine the viability of creating a safe and fun 'thrill-seeker' free-fall experience. As a thought experiment, would it be viable to convert a large building into such a facility? the snow laden fir trees would have to be a cleverly designed alternative: perhaps foam trees with fine upper branches and larger boughs or palm or fern fronds to gently decelerate a human participant. The model should allow overall hight of building to be varied and the ratio of free fall height to height of deceleration zone to be varied. Thus the participant takes the lift to the top floor, walks out on a gangway then leaps carefree into the void space below, briefly experiencing the sensation of free-fall before entering the upper surface of a specially designed 'forest' to slow his fall gradually and gently. After the deceleration he will be deposited unharmed to the ground floor (the forest floor). Obviously, deceleration would have to be gradual. I imagine that the forces experienced whilst jumping on a trampoline would be a good starting point to define reasonable comfort, say 2 or 3g?) Specific questions: given the practicalities and limited height available, over what distance should the deceleration take place to avoid forces greater than 3g, would it be a linear deceleration or exponential? how much heat energy must be absorbed for a 100kg participant? Assumptions: terminal velocity will be achieved after a 450 m, 12 second fall. If space is limited and the free-fall height is 50 meters what height is required for the deceleration zone? As kinetic energy would be transfer to heat, would the 'trees' have to be wet to dissipate this energy and avoid heat burns? or would there be a better method so that participants can leap in everyday clothes?