"All Aircraft can fly just fine with zero pressurization. Remember, some of the most structurelly challenging phases of flight for a commercial Airliner are during take-off and landing-- when there is essentially no differential pressure."
"At cruise, breathing is another matter. Above 25000 ft, time of usful conciousness is a matter of seconds. In fact, in Fighters, the O-2 regulators shift to a "pressure breathing" mode of 100% 0-2 (you must forcefully exhale), this creates a higher partial pressure in your lounges to help transfer 0-2 to brain."
"The damage that could be caused by a "rapid decommpression" is also important. Stuff flying off your Aircraft can hit important things, noteably, control sufaces and motors. In Fighters, we negate this somewhat with a "Combat" setting for pressurization (2-3 PSI differential instead of 9-10 PSI). These low settings give a "cabin" altitude of around 25000 ft at 50000 ft "true" altitude."
Fly Safe, and don't F***-Up!!
Sorry about the spelling, Word is Down.