4 ms·

I'm surprised that after all of these years commercial airliners don't have jettison tubes/boxes/compartments ... A one-way, pressure (and possibly mechanical)

by rsync 3y ago

I'm surprised that after all of these years commercial airliners don't have jettison tubes/boxes/compartments ... A one-way, pressure (and possibly mechanical) airlock (or sphincter ?) that you can force a small item out of. This feature would have been useful even prior to mobile phones and batteries. It is my understanding that jet liners dump fuel anytime it is expedient to[1] so this is hardly the worst outcome in terms of pollution and has, essentially, zero cost over a body of water. Related: I am unsure whether a jet liner can descend to a breathable altitude (say, 10000 feet) and feed "fresh", or ambient, air into the plane. That seems like a nice redundancy to have and I wonder how realistic it would be to implement ... [1] https://en.wikipedia.org/wiki/Fuel_dumping https://en.wikipedia.org/wiki/Fuel_dumping

reisse 3y ago
Jet liners do not need to descend to feed ambient air into the plane. Cabin pressurization is done by feeding compressed air from the engine to air conditioner and then to cabin. So in theory yes, this is possible. However in case of fire, actively feeding fresh air may make things worse by providing more oxygen to burn.
DerekL 3y ago
Airliners are always cycling in fresh air, no matter the altitude.
chha 3y ago
> I am unsure whether a jet liner can descend to a breathable altitude (say, 10000 feet) and feed "fresh", or ambient, air into the plane. That seems like a nice redundancy to have and I wonder how realistic it would be to implement ... This is already in place, and has been since planes began going high enough to require pressurized cabins. The engines basically suck in lots of air which is compressed, resulting in a higher temperature. Most of this goes into the combustion, but some of it goes into other applications, such as the environmental systems supplying the cabin with air. It doesn't have the same effect as opening all the windows in a car, but considering the outside temperature[1] that might not be such a bad thing. [1] - https://www.engineeringtoolbox.com/standard-atmosphere-d_604.html https://www.engineeringtoolbox.com/standard-atmosphere-d_604...
- rektide 3y ago
  Fun fact, the f35 jet fighter has kept needing more and more bleed-air for thermal management, and it's putting more than expected wear & load on the engines. One of the next major upgrades is the P&W Engine Core Upgrade which replaces some of the inner engine, and one of the main features is a greatly increased thermal management capability for the engine, since it has so much more bleed air demand than originally expected. I think maybe more bleed air too? This after GE's proposed XA100 got turned down, which would have been even more of a beast (albeit not fit in the Marines stol jet).
sojournerc 3y ago
In many emergencies pilots will conduct an "emergency descent" down to 10000 as part of the checklist (or memory item). It is a dive that you would never otherwise experience in a commercial jet.
- florbo 3y ago
  I was on a flight where one of the pilots had a heart attack and got to experience weightlessness or close to it for a few seconds. Cool to think about what that felt like now but in moment.. not so much. Anyway, the pilot survived and the delay was surprisingly short given the circumstances.
  - bombcar 3y ago
    “This is your backup pilot speaking. Our captain has gone into cardiac arrest, but we will dive to 10,000 feet and give him a bit of the old spicy bra and have him right back up and you back on schedule in no time!”
  - doktorhladnjak 3y ago
    I had something like this happen once too. “Attention passengers, this is your captain speaking. I’m not feeling well. The first officer will be landing the plane as soon as possible.” I was quite surprised how quickly they can safely and smoothly lane a plane when there’s urgency. We were at the gate with paramedics waiting within 10-15 minutes from cruise altitude, and we still had to backtrack 100 miles or so to the airport. Overall delay was only about 2 hours which was mostly finding another pilot on short notice.

by rsync 3y ago

reisse 3y ago

Jet liners do not need to descend to feed ambient air into the plane. Cabin pressurization is done by feeding compressed air from the engine to air conditioner and then to cabin. So in theory yes, this is possible. However in case of fire, actively feeding fresh air may make things worse by providing more oxygen to burn.

DerekL 3y ago

Airliners are always cycling in fresh air, no matter the altitude.

chha 3y ago

> I am unsure whether a jet liner can descend to a breathable altitude (say, 10000 feet) and feed "fresh", or ambient, air into the plane. That seems like a nice redundancy to have and I wonder how realistic it would be to implement ... This is already in place, and has been since planes began going high enough to require pressurized cabins. The engines basically suck in lots of air which is compressed, resulting in a higher temperature. Most of this goes into the combustion, but some of it goes into other applications, such as the environmental systems supplying the cabin with air. It doesn't have the same effect as opening all the windows in a car, but considering the outside temperature[1] that might not be such a bad thing. [1] - https://www.engineeringtoolbox.com/standard-atmosphere-d_604.html https://www.engineeringtoolbox.com/standard-atmosphere-d_604...

rektide 3y ago
Fun fact, the f35 jet fighter has kept needing more and more bleed-air for thermal management, and it's putting more than expected wear & load on the engines. One of the next major upgrades is the P&W Engine Core Upgrade which replaces some of the inner engine, and one of the main features is a greatly increased thermal management capability for the engine, since it has so much more bleed air demand than originally expected. I think maybe more bleed air too? This after GE's proposed XA100 got turned down, which would have been even more of a beast (albeit not fit in the Marines stol jet).

sojournerc 3y ago

In many emergencies pilots will conduct an "emergency descent" down to 10000 as part of the checklist (or memory item). It is a dive that you would never otherwise experience in a commercial jet.

florbo 3y ago
I was on a flight where one of the pilots had a heart attack and got to experience weightlessness or close to it for a few seconds. Cool to think about what that felt like now but in moment.. not so much. Anyway, the pilot survived and the delay was surprisingly short given the circumstances.
- bombcar 3y ago
  “This is your backup pilot speaking. Our captain has gone into cardiac arrest, but we will dive to 10,000 feet and give him a bit of the old spicy bra and have him right back up and you back on schedule in no time!”
- doktorhladnjak 3y ago
  I had something like this happen once too. “Attention passengers, this is your captain speaking. I’m not feeling well. The first officer will be landing the plane as soon as possible.” I was quite surprised how quickly they can safely and smoothly lane a plane when there’s urgency. We were at the gate with paramedics waiting within 10-15 minutes from cruise altitude, and we still had to backtrack 100 miles or so to the airport. Overall delay was only about 2 hours which was mostly finding another pilot on short notice.