Originally Posted by
deltahotel
Flight deck masks can give air mix or 100% and they can also give over pressure - main use for smoke/fumes so the smoke can’t get into the mask but will also give an element of pressure to assist O2 uptake. Flight deck would be ok for a good length of time purely from an O2 perspective.
Pax masks don’t really seal so it’s only ever going to be O2/airmix at lowish pressure.
At 35000’ it’s minus lots - prob -50. Any time spent above 25000 gives a good chance of decompression sickness (sub aqua experts anyone? Bends chokes creeps staggers).
All the the above says get lower quickly. The 757 (Mr Boeing’s original streamlined crowbar) will do 6000fpm at Vmo, but if it’s a rapid decompress with the probability of structural damage do you really want to descend at Vmo?
Just some thoughts. Slightly easier as a freight pilot as everyone on board will be on the flight deck with proper masks and O2. Much harder with pax from 0 to very old, all of unknown health and no knowledge or training.
No mask can work as a 'pressurized' mask, aka delivering more pressure to the lungs than ambient, as without a pressure suit, the lungs and their muscles have very little capacity to breathe/pump air, as they fight to deflate the lungs with every breath against the oncoming pressure (imagine a balloon and trying to deflate it against pumping). With this limited muscle 'overcapacity', pressurized breathing is only possible with suits that also pressurize the chest area to the same pressure as the breathed gas.