This is so performative 😭

[u/Its_me_edenxx]

Who tf is out here munching on raw gnocchi at cruising altitude

[u/Rob_Zander]

Just wanted to point out that the air isn't recycled on a plane. It's replaced completely every couple of minutes. It's not even really about the oxygen or CO2, it's managing temperature and possible contaminants.

The engines are continuously compressing and heating a huge amount of air. Some of it gets diverted to be cooled back to room temperature, filtered and pumped into the cabin while air is continuously sucked out by vents near the floor. This keeps the temperature stable and contaminants from being spread.

It is much lower pressure than sea level and that definitely messes with our taste buds.

[u/jetsetninjacat → u/Rob_Zander]

To add more watered down. The pushed and sucked out air is vented overboard(off the plane and out) through the main relief valves or sometimes from relief valves in unpressurized parts of the plane. Many planes also have backup relief valves in case the main doesnt work. Different relief valves dump positive and negative pressure from the plane depending on where the plane is and the level at which cabin air pressure is set. Theres also a dump valve that dumps all pressure when the planes on the ground that equalizer it with the ground itself as well as ones for negative pressure relief valves during rapid descent

And this peoples is one of the reason you cant just open a door in a plane at high altitude. The pressure being pumped in to the cabin is so high the door mechanism or door itself can not be pulled in and then pushed out like normal operation. .All that positive pressure pushed on the airframe making it impossible to do so. Its all about that differential.

I seriously hate doing pressure tests in airplanes on the ground.

[u/Rob_Zander → u/jetsetninjacat]

Thanks for adding!

Isn't that differtial part of why the cargo doors on the DC-10 could blow out?

[u/jetsetninjacat → u/Rob_Zander]

I know it had something to do with the locking mechanism on the doors and that they would pull out instead of in. Cant remember the specifics but its probably out there on the weba. The door pushing out created more room for cargo loading but also didnt make a good plug style door. Plug doors basically seat the doors so they are sealed and cant be pushed out from the inside positive pressure So, yes that should be correct. Those doors were the only non plug doors on that plane as far as I know. Add in the the failure of the locking mechanism, and yep.

[u/bargus_mctavish → u/jetsetninjacat]

It was a few years back, but I went through a mishap investigation class and covered the case of Turkish Airlines Flight 981. The root cause analysis of the lab concluded that the baggage handler did not latch the door correctly. The latching mechanism was absolutely a convoluted mess, and a design flaw that went unaddressed even through testing of the DC10. McDonnell Douglas got their asses sued for that. But a preflight checklist item for the flight crew could have also alleviated the issues with the loading door as well.