what will happen to cabin altitude at a higher altitude airport?

Question

during descent, cabin altitude will decrease and then the cabin will completly depressurize on touchdown, BUT will the same happen if the aircraft landed at a HIGHER altitude airport? what will happen? will the cabin altitude decrease fully?

Answer 1

If the aircraft's pressurization system is set properly, i.e. landing elevation set into the pressurization controller in the cockpit, as the aircraft descends to land at the destination airport, the pressuriz. controller descends the cabin at a preset schedule, so that the cabin altitude closely matches the airport altitude at touch-down. When the aircraft settles onto the runway, the WOW (weight on wheels) system or air/ground sense system, fully opens the outflow valve, ensuring the aircraft cabin is at the same pressure as the airport.

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As a maintenance function, we do 'trick' the air/ground (WOW) system and manually pressurize the cabin, taking it below field elevation, when we are checking the cabin for leaks, so it would be possible to land with a cabin altitude below field elevation, but it would require both air/ground sense systems to fail in the 'air' mode and the pressurization system would have to be in the 'manual' mode with outflow valve selected to 'closed'.

Answer 2

On modern airliners, cabin altitude computers use destination airport information from the flight management computers to correctly adjust the cabin altitude to match the destination. In cases where there is no flight management system, or when the FMS and pressurization system are not connected, the pilots can set the altitude of the destination airport so that the pressurization system adjusts the pressure correctly for landing.



The pressure usually isn't equalized perfectly. At some point, the cabin is fully vented to the outside so that it can equalize to exactly the outside pressure. If there's a tiny bit of pressure remaining, it may be low enough to open the doors but high enough to be dangerous. In one incident, a flight attendant opened a door while there was still a small amount of residual pressure and was blown out of the airplane and onto the tarmac (the unlucky FA did not survive).



In cases of really high altitude airports, the pressurization system may raise the cabin altitude and leave it there, since it already matches the destination airport. For example, at many cruising altitudes, the cabin altitude may not need to go any higher than 5000 feet; and if the aircraft is going to be landing at Denver, the pressurization system can just raise the cabin altitude to 5000 feet and leave it there for landing.



In the oldest aircraft, the pilots had to adjust pressurization manually. Then it was up to the skill of the pilots (or the flight engineer) to get the cabin altitude right for arrival.

Answer 3

mjk is almost exactly right. Just one minor correction. I can land with the airplane pressurized well above (cabin pressure) or well below (cabin pressure altitude) these are different ways of saying the same thing. All I have to do is set the landing altitude to say sea level, and then land at DEN where the field elevation is 5300 feet. The cabin, at the point of touchdown will be about 15 psi, or 30 inches of mercury, and the pressure outside the airplane will be around 12.5 psi or around 25 inches of mercury. As soon as the air/ground sensor detect touchdown, the outflow valve will drive full open, and everyone's ears will hurt, pop, or could in extreme cases even rupture as the pressure equalized.



As mjk said, the trick is to set the proper landing altitude in the pressurization controller.



One last point is that for very high altitude airports such a Quito, we will often set a lower landing altitude before takeoff, say 5000', and then adjust it to the proper landing altitude before beginning descent. This is to keep the cabin from being too high during cruise which leads to fatigue.

Answer 4

Now, this is just a guess for the most part, but if I remember from reading about a few crashes caused by faulty cabin pressure equipment, cabin pressure is a fully automatic system, and it maintains a pressure differential of a certain set amount. I think it is basically a "percentage function", so any airport large enough to take a pressurized airliner will be low enough that the actual pressure differential between outside and inside will be insignificant. With modern systems in particular, the plane probably "knows" when it's going into landing mode, and begins to equalize the pressure. The change is small, but if it isn't done, things would be interesting once they open the door! The pressurization system is usually fully automatic, but cabin pressure can be maintained and adjusted by the pilot or flight engineer manually, if the automatic function fails.

Answer 5

A decrease in Cabin Pressure is caused by a leak out of the aircraft or spacecraft. It can be caused by a number of things such as a leak through a valve, leak through the hull, etc. Generally, if the aircraft is going to go above 10,000 ft, it will be pressurized to sea level, however people can function at higher altitudes without a pressurized cabin. Take, for instance, spacewalks. The suits that astronauts use are pressurized to 4.5 psid, which is equivalent to ~26,000 ft altitude. Keep in mind, though, that they are breathing pure oxygen and they have performed procedures that purge nitrogen from the bloodstream to prevent the bends. On the Space Station, we need to keep the crew at a partial pressure of oxygen level above 2.3 psi. At normal air (which it is in an aircraft), that would be a total pressure of 11 psi, which is a little less than 10,000 ft, which is where the 10,000 ft number comes from. The consequences of low oxygen levels would be asphyxiation and you would eventually die. It could be slow, if it's a slow leak, or fast, if it's a fast leak.

Answer 6

i remember that a 757 i once flew had the option of choosing the destination airport altitude. So, the cabin altitude will decrease to the destination airport's altitude to prevent violent drafts when they open the aircraft's door. Which is not fully decreased. Vice-versa also occurs



plz answer:

https://answersrip.com/question/index?qid=20100518193756AA8ROHk

Answer 7

This is from pressurization training or part of ATA 21 given to mechanics, Prior take-off pilot/co-pilots always sets the pressurization control to the altitude of destination airport let us say Katmandu, Nepal around 5000ft above sea level, when the aircraft lands at Katmandu the pressure controller automatically adjusts to the pressure at Katmandu airport say 13.5psi (example figures only). In pressurization always remember these two terms airport of origin and destination airport for pressurization control. This subject is quite hard for first timers almost failed my oral exam (explain aircraft pressurization) on my first ground engineer's course. Lucky our written exam is always (Multiple Guess) so I passed it.

Answer 8

The pressure in the cabin is regulated when in flight. When it lands, it will match the pressure outside. If the airplane landed on a very high airport ... the pressure in the cabin would decrease. Or if at sea level 'may' increase.

Answer 9

Planes have no mechanism to allow cabin pressure to go below outside pressure. The cabin pressure will drop just as it normally does until it equals the outside pressure.

Answer 10

the atc will inform them before decreasing starts