so looks like the death line is around 23,000ft (for imperialists out there). even a relatively short flight from what I've experienced tends to go significantly above that, nevermind the sub-antarctic temperatures. do 1/4th of all stowaways have the latest mountaineering gear and training, and are lugging a giant oxygen tank?
there must be something a bit different about that landing gear space, compared to the conditions outside the plane. maybe it's slightly more pressurized somehow?