[TylerE]

It won't unless there is some sort of major hull leak. If it was off long enough it would start to be a problem. Its basically the same same as turning off recirc on your car's climate controls. (Also, the pressurization controls are almost always on the overhead panels, which contains things that are used almost always for startup/shutdown steps so it's not like the pilot is going to reach over to adjust a radio or the autopilot and hit the bleed air.

Really though there are plenty of switches in any cockpit that will result in the death of all aboard if no corrective action is taken.

Do you freak out about driving? Plenty of controls in your car you could say the same thing about. Yanking the ebrake at highway speeds in rush hour traffic isn't gonna end well.

Edit the 5th or so: There are also times when the pilot will legitimately and safely depressurize in flight, like when descending to the one of the super-high airports that are actually at higher altitude than typical cabin atmosphere, like La Paz Bolivia (over 13000ft, compared to a typical cabin altitude of 5-8000 or so. They do it gradually while descending, so they don't make everyones ears go bang all at once.

Edit the 6th: Also, there's a big difference between turning off bleed air (which is pretty benign) and actually hitting the emergency pressure dump control, which is protected by a guard that holds the switch in the normal/auto position.

[Ajedi32]

I think the difference is that in a car, any action that could kill the passengers is nearly as likely to kill the driver as well. Obviously you can't stop the pilot from crashing the plane and killing everyone, but it's still pretty creepy to learn that there's a "kill all passengers but leave me alive" switch in every plane, in a locked cockpit inaccessible to the people whose lives are affected by that switch.

[nawgz]

This is a really weird characterization of a normal airplane function.

First, you are seeming to act as if the power between passengers and pilots should be equal. Why would this ever be? The pilot has all the power and the passengers none. Thinking of past hijackings, it's obvious that it must be this way.

Second, the plane needs to be able to handle all sorts of 1 in a million events. Recall there were around 22 million flights in 2021, and of those, exactly 1 was involving a Boeing or Airbus jet (maybe that's even true for Embraer or Bombardier and that tier of airliner). This is because the pilot has a vast amount of controls that are required to handle various events. A plane is a pressurized tube flying thru the sky, of course controls for pressure in the cabin must exist to allow equalization under aberrant circumstances.

Finally, activating this "kill" switch would drop oxygen masks to every passenger in the plane automatically; the pilot does not have any say in this matter. While these masks obviously have limited duration, there isn't exactly a way the pilot could perform this mass murder without their own death or imprisonment being guaranteed too. Frankly, I find your representation of the purpose of the switch so immature as to be offensive.

[Ajedi32]

I didn't say it was a bad idea with no legitimate purpose, just that it's pretty creepy. Given that it's only been used to commit mass murder ~once (at most), it's probably not worth implementing any mitigating controls.

[bigDinosaur]

If the pilots want to kill you, all they have to do is fly into the ground, and there's absolutely nothing you can do to stop them and nothing short of complete automation could ever remove that risk. I can't think of scenarios where the pilots would particularly want to survive after murdering all their passengers.

[mariuolo]

With https://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_702 when the co-pilot hijacked the plane to ask for political asylum in Switzerland, I remember news coverage reporting that he had threatened the passengers to cut off the air supply if they didn't remain seated.

Must have been quite distressing.

[apexalpha]

This just reinforces the argument that the pilot is in control, and he can do as he likes. Fly normally, change course, kill everyone... When you step into a plane you put your life in the hands of a pilot.

[phire]

> and actually hitting the emergency pressure dump control

Wait, is there an emergency pressure dump control?

I kind of just assumed turning off bleed air would be the only option, and I would have assumed that turning off bleed air would complete depressurisation within a few min.

[TylerE]

Yes. You’d use it in the case of something like a fire where you need to get the smoke out NOW

Here’s what it looks like on a 737: http://www.b737.org.uk/images/cpcspanel.jpg

The switch is the guarded toggle a bit left of center on the bottom, next to the two round gauges.