Oxygen is much thinner at 33,000 feet. You can still breath at 15,000 feet, most of us have hiked up a mountain almost that tall. In the USA, if you live out We

Oxygen is much thinner at 33,000 feet. You can still breath at 15,000 feet, most of us have hiked up a mountain almost that tall. In the USA, if you live out West and do a lot of hiking, you've probably gone up at least 12,000 and maybe 14,000, so you understand what 15,000 is. But 33,000 feet? That is much more difficult to survive.