Questions tagged [cabin-pressure]

Airplane cabins are pressurized so that the air inside remains breathable at high altitudes.

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19
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5answers
11k views

Why is air mixed with bypass air on the A/C of an aircraft?

Air is taken from the compressors, then it is cooled by the air that comes from the ram air inlet. After that, it is compressed and cooled again by an expansion turbine. When finally air is condensed, ...
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3answers
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Are cargo holds pressurised these days?

This question is only regarding aircraft that seat more than about 100 people. Are cargo holds pressurised these days, what is the situation? Are only some pressurized, most, of every single one? ...
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Would failure to put on an oxygen mask during loss of cabin pressure result in death?

I was trying to explain to someone why the cabin is pressurized (no one wants hypoxia) and that led to discussion about the emergency oxygen masks available on airliners. If a person didn't put on ...
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1answer
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Why is cabin pressure increased above ambient pressure on the ground?

As far as I know at least some (e.g. some Bombardier Dash-8 series) airplanes during takeoff may increase cabin pressure above air pressure on the ground, before starting to decrease it. In one case ...
10
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2answers
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How hot would pressurized air get if the air conditioning failed?

I understand that aircraft are pressurized by pushing air into the cabin using the engines, and using a valve to let the air escape at a controllable rate thus achieving the desired pressure ...
11
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2answers
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Why is the compressed air (from engine compressors) taken from High Pressure (HP) stage instead of Low Pressure (LP) stage?

An aircraft that uses Turbofan or Turboprop engines would be taking the compressed air from 3rd stage and 6th stage (varies) and supplying it to the Pressurisation and Air Conditioning Kit (PACK). ...
30
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1answer
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Why is there a hole in one of the layer of an airplane's windows?

On a commercial airliner, there is a hole in one of the layer of the passenger windows. See here: and here: Or in more detail: Can you explain the physical reasons for this design choice?
19
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Does the B787 (Dreamliner) operate with higher cabin pressure?

The Boeing 787 Dreamliner's fuselage is almost completely made of composite carbon fibre material, which is not susceptible to metal fatigue. The main reason why the cabin pressure in a pressurized ...
17
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1answer
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How is the cabin pressure maintained inside aircraft?

When aircraft is at high altitude, atmospheric pressure will be too low but inside aircraft pressure is maintained such that it is comfortable for crew and passengers. But how is it maintained? As I ...
36
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5answers
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How does an airliner deal with cabin altitude at an airport above 8000 ft?

There are a number of airports above 8000 ft altitude. FAR 25.841 states: Pressurized cabins and compartments to be occupied must be equipped to provide a cabin pressure altitude of not more than ...
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2answers
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How much air is recirculated (vs. bleed air injected) in modern airliners cabin?

Air in the cabin of airliners is a mix between: new air (engine bleed air or ram air in some aircraft) and recycled air pumped out of the cabin, filtered and re-injected. How much air is ...
9
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1answer
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How does the cabin pressure controller work in a large commercial airliner?

The cabin pressure controller controls the pressure in the cabin in relation with aircraft altitude, and a manual control is possible using the overhead panel: A320 Air Conditioning and Cabin ...
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How thick is the skin of an aircraft like the Airbus A350 or Boeing B777?

We can evaluate how thick walls are by looking at door or window frames, however that isn't representative of an aircraft fuselage, which appears to be very thin: Airbus A350 XWB forward fuselage, ...
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5answers
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Could a pilot incapacitate other crew/passengers by manipulating cabin air quality/pressure?

Could a pilot of an airliner incapacitate everyone outside the cockpit by somehow triggering a loss of cabin pressure while simultaneously disarming the airplane's oxygen masks, manipulating the air ...
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3answers
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How do big planes like 737 manage fresh air for passengers during flight?

How do the big planes (e.g. A380 or 737) flying on high altitudes manage to get fresh air for passengers and crew during the flight? I know the inner space of the plane used for passengers and crew ...
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2answers
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Can an aircraft re-pressurize at high altitude?

When parachute jumps are performed from 32000 feet (or between 28000 - 30000 feet), once the jumpers are let out from the aft (cargo area), does the aircraft need to change altitude (e.g. descent)? ...
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Do pilots breathe the same air as passengers?

Do pilots breathe the same quality of air as passengers ? (i.e. identical parameters: same O2, CO2 and O3 levels, same temperature, same humidity, etc.) Do pilots breath the same air as passengers (...
13
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1answer
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How long will one remain conscious in the event of a sudden cabin depressurization?

I know the usual scenario is where an airliner suffers from an explosive decompression and the oxygen masks drop and the plane descends to a safer altitude but..... This is a purely hypothetical ...
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4answers
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Are fighter jet cabins pressurized?

I heard once that fighter jet cabins are NOT pressurized, but the pilot's suit is, which prevents problems with decompression if the cabin gets shot. But a military fighter pilot much later told me ...
16
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1answer
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Is it possible to suffer barotrauma during decompression?

Barotrauma is damage of lungs by air overpressure and may occur at overpressure as low as 30 kPa (4 psi). Overpressure in most aircraft is about double that value. So is it possible to suffer ...
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Does oxygen become less available during night-time?

The following excerpt is from the FAA's Pilot's Handbook of Aeronautical Knowledge (page 7-37): Some people flying above 10,000 feet during the day may experience disorientation due to the lack ...
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1answer
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At which point does an airliner start to pressurize/depressurize the cabin?

Do airliners start changing cabin pressure at takeoff or after reaching a certain altitude? Also when do they start depressurizing the cabin ?
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What's the relation between cabin pressure and altitude?

Usually, cabin pressure of an airliner is kept at a value corresponding to an altitude of not more than about 2000m. Now, I heard that before takeoff, the pressure is already increased a little for ...
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5answers
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Is constant air pressure maintained inside the fuselage?

I just heard it somewhere but I'm not sure about it. If it is, then why don't they build airtight fuselages?
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2answers
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How does the outflow valve work on a cabin pressurization system?

When you fill up a cabin with warm air the pressure of the cabin will rise. An outflow valve controls the desired pressure. But with pressure rising doesn't the temperature rise because you're ...
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1answer
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What areas of a commercial airliner are pressurized besides the cabin?

For example, what about the baggage compartment? Landing gear housing? Avionics?
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Why does cabin air have to be dehumidified?

When air is piped in from outside and into a pressurized cabin, it is also dehumidified in the process. All airlines provide beverage service on even short-haul flights to combat the dryness of the ...
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1answer
622 views

Would discharging a firearm in-flight cause an explosive decompression?

I was reading a BBC FAQ about Federal Air Marshals, which has this chilling quote in it: A gunfight on a passenger airliner is seen as an option only of last resort. Presuming an air marshal has ...
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4answers
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Can an airliner provide ground level cabin pressure, temperature, humidity etc?

Apart from the cost angle, which seems to be the biggest factor in airlines, is it technically possible to bring cabin atmosphere (includes pressure, temperature, humidity) etc. at par with ground ...
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When is an aircraft required to be pressurized?

For example a Cessna Grand Caravan doesn't have a pressurization system, but a Phenom 100 is pressurized, so what are the main reasons a manufacturer has to build an aircraft with a pressurization ...
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5answers
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Should depressurization be considered in the event of an inflight cabin fire?

Uncontrolled cabin fires only need a few minutes to spread throughout the cabin of an aircraft, killing everyone onboard and destroying the airframe. Now, we all know that depressurization and fire ...
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How to do a Rapid Descent in a jet with inoperative spoilers?

So, let us assume you are in a simulator for your favorite jet plane, and the instructor gives you a LOFT (Line-Oriented Flight Training) scenario that goes as follows: A normal takeoff and climb to ...
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2answers
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Does the Airbus A350 have an Automatic Emergency Descent System?

In 2009 Airbus went public with a new feature in the Airbus A350, an Automatic Emergency Descent (AED) System. The system would detect a rapid depressurization and, after a defined waiting time, ...
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1answer
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Which was the first pressurized aircraft?

Which aircraft was the first one to fly pressurized? High altitude breathing apparatus, 1918 (source) I mean an aircraft which didn't require to don an oxygen mask above a certain altitude, ...
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2answers
14k views

Are there any pressurized piston-engine aircraft?

Are there any pressurized piston engine-powered aircraft? Or does pressurization require a turboprop or jet?
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Why does the cabin air sometimes smell of kerosene? [duplicate]

Why does the cabin air sometimes smell of jet fuel, although bleed air is tapped before it comes in contact with fuel ? How is this possible? I have smelled this a couple of times in my life (twice ...
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1answer
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What can I do to save my life if oxygen masks fail to drop down? Is it possible?

What is the safest and fastest solution (method) in this situation?
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Why do airliners have “pressure bulkheads”?

Image source: FAA What part of the fuselage aft of the bulkhead would leak pressure? Or is it just there to reduce stresses? How does a DC-9/MD-80/90 incorporate aft bulkheads when there's a ...
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2answers
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Has the typical cabin pressure in airliners changed in recent decades?

Two or three decades ago, I would experience quite uncomfortable blocking of the eustachian tubes, which would noisily unblock and become blocked once more as the plane descended. I haven't ...
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1answer
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If the pilot cabin loses pressure, can the pressure difference lock the cockpit door?

I think, if there is only a 0.1 bar pressure difference with a single square meter door, around the weight of a ton would be needed to open it - if it is sealed hermetically and opens outward. Is it ...
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1answer
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In an unpressurized cabin, why is the cockpit ambient pressure lower than the outside pressure?

As I study for my IRA written, this (VFR) question resurfaced and continues to irk me. The annotations cite the Venturi effect as the sole reason, but I don't follow. From Wikipedia: "The Venturi ...
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1answer
158 views

How does a DC-10 flight engineer manually raise the cabin altitude?

Reading into Federal Express Flight 1406 and I noticed when the flight engineer said he was raising the cabin altitude “manually” I assume this has something to do with cutting off the oxygen, but how ...
4
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1answer
359 views

How do wide-bodied commercial aircraft achieve pressure equivalent to 6000 feet altitude?

I read an LA Times article which states the following. To reduce the stress on the traditional metal frame, airlines now pressurize the cabin to be closer to the pressure outside. When a plane is ...
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1answer
291 views

Do people get less airsick if cabin pressure is at 6000 ft.?

This is in relation with a question I asked yesterday . This is part two of the question. Do people feel less discomfort. Whenever I'm traveling on planes, at times I feel strain in back of the head, ...