7 ms·

"Before Fariq can attempt to get back into the cockpit, Zaharie reaches up and flips the pressurization switch, cutting off bleed air to the cabin. The airplane

"Before Fariq can attempt to get back into the cockpit, Zaharie reaches up and flips the pressurization switch, cutting off bleed air to the cabin. The airplane rapidly begins to depressurize." I really want to believe that a single switch doesn't control whether people in the back of the plane can breather or not...

TylerE 4y ago
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 4y ago
  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 4y ago
    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 4y ago
      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 4y ago
        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 4y ago
        With https://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_702 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.
- phire 4y ago
  > 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 4y ago
    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 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.
mlyle 4y ago
It's about that easy. Of course, masks are a-gonna drop, and flight attendants are going to put on portable oxygen bottles... and of course the crew should descend. But the whole plane architecture is built on the idea that you're trusting the people in the front with everyone's lives.
- stouset 4y ago
  I think the point being that accidentally hitting this switch is probably of some concern.
  - EdwardDiego 4y ago
    After a few crashes that bad UX played a part in, I'm reasonably confident that in a modern aircraft that switch is somewhere hard to press accidentally. (E.g., fuel selector switches that can enter an unexpected state while looking like they're in the correct state, take-off/go-around switches that could be triggered by a first officer wearing a watch reaching for the speed brake lever, attitude indicators with ambiguous backgrounds, three-pointer/drum-pointer/counter-pointer altimeters)
  - outworlder 4y ago
    That's some accident. The pressurization controls are overhead in a not very central location.
  - jaywalk 4y ago
    It's not going to be accidentally hit. And even if somehow it does get hit accidentally, there's a CABIN ALTITUDE warning that would go off before it becomes a problem.
  - mlyle 4y ago
    Modern aircraft have very good warning systems that warn when configuration of the aircraft or systems necessary for life are in incorrect states, and the way they're used generally afford a decent chunk of time if something goes wrong.
  - ploum 4y ago
DogLover_ 4y ago
You might want to learn about Helios Airways Flight 522 crash
- EamonnMR 4y ago
  That one haunts my nightmares.
  - threads2 4y ago
    WOW I will never sleep on a plane again.
    - justsid 4y ago
      No worries, if pressurization is lost, your body will do the sleeping all by itself.
- yesenadam 4y ago
  https://en.wikipedia.org/wiki/Helios_Airways_Flight_522 https://en.wikipedia.org/wiki/Helios_Airways_Flight_522
  - reddit_clone 4y ago
    Oh.. Why _did_ I click on that ? :-(
- quickthrower2 4y ago
  That was a missed checklist item IIRC where the ground engineer had turned off the pressurisation while trying to debug a pressure leak (ironically), the pilot was supposed to check this in a couple of lists, they did but I think they glossed over it. Plus they might have ignored some inflight warnings. This is also the one where a learning pilot (also scuba diver, probably able to handle the lack of oxygen better) tried to save it but was too late.
whywhywouldyou 4y ago
What's with so many of these comments being flabbergasted that there's a switch in the cockpit that can cause harm to everyone on the plane? Do you realize you're entrusting two people in the front of the plane with your life as soon as the plane takes off? There are probably DOZENS of switches that if they are flipped maliciously will result in everyone on the plane dying.
- guntherhermann 4y ago
  I think the difference is the that those other things affect everyone on the plane, but depressurising only the cabin, doesn't.
  - lazide 4y ago
    It also impacts the pilots (they don’t have their own pressurized area, it’s the same), but the pilots have more oxygen. Which is a really good thing 99.999% of the time.

TylerE 4y ago

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 4y ago
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 4y ago
  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 4y ago
    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 4y ago
      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 4y ago
        With https://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_702 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.
phire 4y ago
> 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 4y ago
  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 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.

mlyle 4y ago

It's about that easy. Of course, masks are a-gonna drop, and flight attendants are going to put on portable oxygen bottles... and of course the crew should descend. But the whole plane architecture is built on the idea that you're trusting the people in the front with everyone's lives.

stouset 4y ago
I think the point being that accidentally hitting this switch is probably of some concern.
- EdwardDiego 4y ago
  After a few crashes that bad UX played a part in, I'm reasonably confident that in a modern aircraft that switch is somewhere hard to press accidentally. (E.g., fuel selector switches that can enter an unexpected state while looking like they're in the correct state, take-off/go-around switches that could be triggered by a first officer wearing a watch reaching for the speed brake lever, attitude indicators with ambiguous backgrounds, three-pointer/drum-pointer/counter-pointer altimeters)
- outworlder 4y ago
  That's some accident. The pressurization controls are overhead in a not very central location.
- jaywalk 4y ago
  It's not going to be accidentally hit. And even if somehow it does get hit accidentally, there's a CABIN ALTITUDE warning that would go off before it becomes a problem.
- mlyle 4y ago
  Modern aircraft have very good warning systems that warn when configuration of the aircraft or systems necessary for life are in incorrect states, and the way they're used generally afford a decent chunk of time if something goes wrong.
- ploum 4y ago

DogLover_ 4y ago

You might want to learn about Helios Airways Flight 522 crash

EamonnMR 4y ago
That one haunts my nightmares.
- threads2 4y ago
  WOW I will never sleep on a plane again.
  - justsid 4y ago
    No worries, if pressurization is lost, your body will do the sleeping all by itself.
yesenadam 4y ago
https://en.wikipedia.org/wiki/Helios_Airways_Flight_522 https://en.wikipedia.org/wiki/Helios_Airways_Flight_522
- reddit_clone 4y ago
  Oh.. Why _did_ I click on that ? :-(
quickthrower2 4y ago
That was a missed checklist item IIRC where the ground engineer had turned off the pressurisation while trying to debug a pressure leak (ironically), the pilot was supposed to check this in a couple of lists, they did but I think they glossed over it. Plus they might have ignored some inflight warnings. This is also the one where a learning pilot (also scuba diver, probably able to handle the lack of oxygen better) tried to save it but was too late.

whywhywouldyou 4y ago

What's with so many of these comments being flabbergasted that there's a switch in the cockpit that can cause harm to everyone on the plane? Do you realize you're entrusting two people in the front of the plane with your life as soon as the plane takes off? There are probably DOZENS of switches that if they are flipped maliciously will result in everyone on the plane dying.

guntherhermann 4y ago
I think the difference is the that those other things affect everyone on the plane, but depressurising only the cabin, doesn't.
- lazide 4y ago
  It also impacts the pilots (they don’t have their own pressurized area, it’s the same), but the pilots have more oxygen. Which is a really good thing 99.999% of the time.