The highest I jumped without oxygen was 17.7k ft (couldn't quite get that extra 300 feet), and I was quite hypoxic. The odd thing is, I had no awareness of my

The highest I jumped without oxygen was 17.7k ft (couldn't quite get that extra 300 feet), and I was quite hypoxic. The odd thing is, I had no awareness of my impaired cognitive ability and I basically staggered out of the aircraft. I wasn't thinking straight for half of the jump. I now think i'd be much more aware of the effects and impact of hypoxia, because i've experienced it. I've also done the opposite by scuba diving to 30m and begun to get nitrogen narcosis, which is very similar. To understand it better, I've done a "dry dive" in a controlled environment in a hyperbaric chamber where they can simulate a 40m dive, and measure your cognitive ability throughout. This is excellent awareness training, and I now think i'd identify the early signs of it sooner.