Hitting a net 1/3 the size of a football field seems to be the second of his worries. I'm wondering about the first minute or so of the jump. Terminal velocity of a skydiver, that is, when the person no longer accelerates because wind resistance offsets gravity acceleration is around 60 meters/second or 200 ft/sec. If he jumps at 25 Kft, it will take around 45 seconds to reach 18 kft, where the air is still pretty thin. After that, he will have a minute down to 5 kft, which is when he better start looking for the net. He will have only 25 seconds to zero the net after that. If the guy is disoriented in the beginning due to oxygen problems and doesn't recover in a minute, he could have a big problem.