Jumping without a parachute (and even with it; nor other factors that will slow you down or cushion the fall, etc) from 300m onto hard concrete is a bad idea.

Jumping without a parachute (and even with it; nor other factors that will slow you down or cushion the fall, etc) from 300m onto hard concrete is a bad idea. You are welcome to test the opposite hypothesis, please send postcards from after the jump.