When doing a skydive from 30,000 feet, you must breathe pure
oxygen on the ground for 45 minutes to purge your bloodstream
of nitrogen. Nitrogen bubbles in your blood could cause the "bends"
when you get up to 30K. At 30K, most people will loose
consciousness in about 30 seconds without pressurized oxygen and a mask
on. We used military oxygen masks connected to an on-board oxygen
system and then switched over to a personal "bailout bottle" that
supplies oxygen during freefall. The bottle contains about 15 minutes
of air - more than enough time to get back to earth unless you open
your canopy too high. This is not a good thing.
Skydivers wishing to make a HALO
jump must have a skydivers D-license
(500 jumps), take a pilots flight physical, and train in a USAF high
chamber. The D-license now costs about $12,000 USD (training + jumps). I
got by much cheaper, since the old D-license requirement was 200
jumps. I currently have 350 jumps in my logbook. The rig (parachutes, container, and other gear) costs between $1800 to
$5000 depending on how fancy you want to get and if you buy new or
used. The flight physical costs about $100, and the altitude chamber
ride was $50, not counting the hotel and travel. The jump itself
was $600, again, not counting hotel and travel. Would I do it
again?.... HELL YES!
To learn more about
high altitude parachute jumps and the effects of high altitude on the
human body click