Our local flying group did a trip to Beale Air Force Base to take the FAA high altitude training.
13 days without any DUIs, good job guys!
After several hours of ground review and classes, we went into the actual chamber where they lean the air to 25,000ft (that was after 30mn of breathing pure O2 to prevent decompression sickness).
I actually felt ok, but didn't look so fresh on some pictures :)
The time was interesting, but too short. I obviously seemed to be suffering from the lack of air a little bit, but didn't feel I was doing too badly. I'm still curious how far I was from passing out or being able to turn my own O2 back on.
On the way back, we got to see some U2 flying patterns:
that was after about 5mn at 25,000ft without any oxygen
and a few shots from the flight back: