Talk:Cabin pressurization

message: Where is the merge discussion?  I have started it here because it links here but the merge proposer needs to explain the arguement for it first.
* Do not merge because:  Unplanned cabin depressurisation is very specific to Cabin pressurization and is useful here.  Uncontrolled decompression is a general case.  Ex nihil (talk) 01:04, 7 August 2008 (UTC)
thread_title:  Merge proposal 

message: Some people think that the Lockheed XC-35 was the first, and not the Boeing 307; However the first did not enter production.
 
Dagoflores --189.166.14.226 (talk) 08:20, 12 January 2008 (UTC)
replies: text: That does not mean that the XC-35 was not the first pressurized aircraft. That would be like saying that the Bell X-1 was not the first supersonic aircraft because it did not go into production. Ratsbew (talk) 20:17, 20 November 2008 (UTC)

text: Well, the Ju49 was making high altitude flights by 1935, and the XC-35 did not fly until 9 May 1937, you work it oput!Petebutt (talk) 09:14, 16 March 2010 (UTC)
thread_title:  First aircraft 

message: Does anyone know what the difference between the pressure in the cabin relative to the cargo area is?
How much pressure is your luggage subjected to (if the pressure in the cabin is 0.7 bar? 
When does spray bottles break?
Thanks —The preceding unsigned comment was added by 63.240.133.93 (talk) 02:07, 16 March 2007 (UTC)
replies: text: My uncle (a retired airline pilot) said that the cargo area is pressurized exactly the same as the cabin since they often carry pets down there. In newer planes it is even heated and uses the same ventilation system as the regular cabin.-- Nick. 08:49, 21 September 2007 EST.  —Preceding unsigned comment added by 65.112.23.131 (talk)  
Most cabin cargo bins are pressurized, although there are exceptions.  As for heating, some bins have their own heaters, and some receive residual heat from the passenger cabins.  In the second case (residual heat), the bins can get chilly. Mikepurves (talk) 09:06, 26 July 2008 (UTC)
thread_title:  Difference between cabin and cargo 

message: "An otherwise-harmless pinhole under these pressure differences will generate a high-pitched squeal as the air leaks out at supersonic speeds[citation needed]." 
--This does not seem right, because even assuming a complete vaccum (due to aerodynamic effects, if any)  just outside the skin of the aircraft, the pressure differential is less than 10 PSI, and a pinhole in a car tire (30 psi)  does not generate such a loud noise.  —Preceding unsigned comment added by 200.170.108.84 (talk) 21:42, 6 February 2008 (UTC)
thread_title:  Pressure and speed of escape at a pinhole 

message: I don't have the data, but this blanket assertion is highly dubious.  There are many variables which go into the rate of decompression.  
First, all airliners are continously pumping in fresh air, and dumping pressurized air overboard.  On virtually all jet transports, the engines pump pressurized air into the plane (the 787 will have a separate compressor system).  "Outflow valves" leak the cabin air overboard, and the pressurization controller controls the rate in which the outflow valves leak the air overboard.  All airliners have unintended leaks (some more, some less), and the pressurization controller closes the outflow valves more to compensate.
If the airplane suffers a large-enough hole, the outflow valves will close altogether while fresh air continues to be pumped into the plane.  If the hole is too large, the airplane will begin to lose pressure (failure of all engines would have a similar effect as all incoming air would be shut off).  Legend says (I cannot confirm this) that the Boeing 777 can maintain pressure with three windows out.
The total pressure vessel volume, the inside/outside pressure differential, the rate of air inflow and the rate of air outflow will determine how quickly an airplane will depressurize.  A blanket statement that a 5' diameter hole causes instant decompression is far too oversimplified and almost certainly at odds with the facts.  It fails to take into account different airplanes' cabin volumes (an Airbus 380 or a Boeing 747 has a bit more volume than, say a DC-9 or F-28), different engine, and the different cabin inflow and outflow configurations.
Finally, remember that a cabin which is not maintaining pressure ("leaking up") is not the same thing as an instant equalization with the ambient (outside) air pressure.  To instantly equalize the pressure of a large volume of cabin air with the outside, the hole has to be massive, e.g., the airplane blown in half.  A slower decompression allows plenty of time to address the problem while oxygen masks are deployed and a descent is started.
Mikepurves (talk) 06:13, 26 July 2008 (UTC)
thread_title:  "A 5' hole will decompress an airliner in a fraction of a second" 

message: I believe that this article has improved very considerably since rated start class and I have listed it for re-assessment at Wikipedia:WikiProject Aviation/Assessment. Ex nihil (talk) 00:27, 2 October 2008 (UTC)
replies: text: Have Assessed as 'B'. As for improvement, it wouldn't hurt to add another image however, and a few more citations in the lead. \ / (⁂) 11:56, 10 October 2008 (UTC)
thread_title:  Rating re-assessment 

message: Can I suggest using only fractions of atmospheres for the pressure units in this article? Bar/KPa are essentially this already but is there any reason that someone would need to know that the pressure is 12 psi? Wouldn't they then compare that to atmospheric pressure of 14.5psi?  —Preceding unsigned comment added by Shniken (talk • contribs) 05:44, 4 June 2009 (UTC)
thread_title:  Units 

message: Re: "The low local partial pressure of carbon dioxide (CO2) causes CO2 to out-gas from the blood raising the blood pH and inducing alkalosis." The partial pressure of carbon dioxide at sea level is approximately 0.2 mm Hg (pressure at sea level = 760 mm Hg x percentage CO2 = 0.03%). The partial pressure of carbon dioxide in the alveoli of the lungs (and in arterial blood) is 40 mm Hg. Thus even at sea level the CO2 in the body is at almost 200 times that in the ambient atmosphere. The fall in carbon dioxide is mainly due to hyperventilation (increased rate and depth of breathing), caused by the low oxygen concentration at altitude. At very high altitudes it is irrelevant, as you will lose consciousness in seconds due hypoxia.  —Preceding unsigned comment added by Mjwciw (talk • contribs) 10:04, 18 July 2009 (UTC)
thread_title:  Carbon Dioxide: a small point of physiology 

message: "Pressurization is essential over 3,000 metres (9,800 ft) to prevent crew and passengers from becoming unconscious through the lack of oxygen (hypoxia) in the thin air above that altitude."    This statement as it stands is nonsense.   People do not become unconscious at 3000 meters.   How do you think people live in Bolivia ? Eregli bob (talk) 12:08, 28 August 2009 (UTC)
replies: text: Sorry, but that is not accurate. Flight crew are required to use supplemental oxygen for cabin altitudes of 12,500 to 14,000 ft. when the duration is more than 30 minutes. And to use it for the entire time, if the altitude is 14,000 or higher.  FAR 91.211. EditorASC (talk) 08:52, 21 December 2016 (UTC)
thread_title: Nonsense statement

message: I have removed note # one, which read thus:
 ::"1. ^ Notable exceptions include the Airbus A380, Boeing 787 and Concorde"
For these reasons:
*  The Concorde is not a notable exception any more than the other 8,000 aircraft, which were certified prior to the new (1996, FAR 25-87) certification rules. Exceptions to that new rule, are only among the "newly designed" aircraft.  Concorde was one of the older aircraft designs, that were certified long before the new revision.
*  The subsequent paragraph in the article, explains the successful exemption of the A380 (Either A380, or Airbus 380, but not both ways at the same time), complete with the appropriate citation, so there is no necessity to add an un-citated note to the previous paragraph.  If the B787 has also been exempted, then the appropriate way to include that information, is to put it in the same paragraph with the A380 exemption and then to attach the proper citation, which also verifies that statement. 
Here is how the subsequent paragraph currently reads: 
::However, companies that build the newer designed aircraft can apply for exemption from that more restrictive rule. In 2004, Airbus successfully petitioned the FAA to allow cabin pressure of the A380 to reach 43,000 feet in the event of a decompression incident, and to exceed 40,000 feet for one minute. This special exemption allows the A380 to operate at a higher altitude than other newly designed civilian aircraft, which have not yet been granted a similar exemption.[8]
Further exemptions of the "newly designed" planes should be added to that paragraph, with their verifying citations. EditorASC (talk) 01:38, 6 October 2009 (UTC)
replies: text: I will search for evidence, but I think you will find that the small windows on Concorde and Tu-144 are dure to the need to keep cosmic radiation inflow to a minimum. Shoot me down if I'm wrong!Petebutt (talk) 08:48, 16 March 2010 (UTC)
replies: text: If a window should fail, how rapidly the cabin altitude climbs, would be a function of the size of that lost window.  The larger it was, the more rapidly the cabin altitude would climb and that would increase the danger of injury or death to passengers.  I don't have the specs available, but my guess is that the loss of just one of those smaller windows, would result in a rather slow climbing of the cabin altitude, since the outflow valves would slam shut and the cabin air escaping thru that smaller window, wouldn't be too much more than the amount that the exhaust valves permitted, while keeping the cabin below the maximum limit altitude, under normal conditions. Thus, it makes sense that using smaller windows did provide a greater safety margin, in the event of the failure of one window. The subsequent emergency descent would take longer to reach a "safe" altitude, simply because the plane was flying at least 20,000 ft higher than other types of airliners. Using smaller windows is a logical way to offset the additional time it would take to make a rapid descent to a lower, safe, altitude, if a window did fail. EditorASC (talk) 09:36, 16 March 2010 (UTC)
replies: text: " ... the need to keep cosmic radiation inflow to a minimum. Shoot me down if I'm wrong!" - sorry, you are wrong. As EditorASC writes, Concorde's windows were the size they were to limit the amount of cabin air escaping should a window break at 60,000 feet. In this case the aircraft would immediately slow down to below Mach 1 and begin an immediate descent, which would be very rapid as the aircraft was certified to use reverse thrust on two inner engines in flight, thus allowing a rate-of-descent of something like ten thousand feet per-minute. IIRC, after the initial Concorde design was completed the cabin pressurisation system was subsequently uprated in capacity to allow for the loss of a single window so enabling less rapid descents should a window fail. IIARC, the cabin windows themselves were triple-glazed, both for strength and for heat insulation, due to the outside skin temperature which was around 90C at Mach 2.— Preceding unsigned comment added by 95.149.173.74 (talk) 16:03, 16 May 2016 (UTC)

text: Perhaps if you read the Altimeter and Atmospheric pressure articles, you'd understand the relationship between air pressure and altitude (and hence how the former is derived from the latter, e.g. at El Alto International Airport)  Socrates2008 (Talk) 12:16, 16 March 2010 (UTC)
thread_title: Pressurized flight

message: Concorde had to deal with unusually high pressure differentials, as of necessity it flew at unusually 
high altitude (up to 60,000 ft) while the cabin altitude was maintained at 6000 ft."Human Factors in the Concord".  This made the vehicle significantly heavier and contributed to the high cost of a flight. Concorde also had to have smaller than normal cabin windows to limit decompression speed in the event of window failure. 
:I will search for evidence, but I think you will find that the small windows on Concorde and Tu-144 are dure to the need to keep cosmic radiation inflow to a minimum. Shoot me down if I'm wrong!Petebutt (talk) 08:48, 16 March 2010 (UTC)
replies: text: If a window should fail, how rapidly the cabin altitude climbs, would be a function of the size of that lost window.  The larger it was, the more rapidly the cabin altitude would climb and that would increase the danger of injury or death to passengers.  I don't have the specs available, but my guess is that the loss of just one of those smaller windows, would result in a rather slow climbing of the cabin altitude, since the outflow valves would slam shut and the cabin air escaping thru that smaller window, wouldn't be too much more than the amount that the exhaust valves permitted, while keeping the cabin below the maximum limit altitude, under normal conditions. Thus, it makes sense that using smaller windows did provide a greater safety margin, in the event of the failure of one window. The subsequent emergency descent would take longer to reach a "safe" altitude, simply because the plane was flying at least 20,000 ft higher than other types of airliners. Using smaller windows is a logical way to offset the additional time it would take to make a rapid descent to a lower, safe, altitude, if a window did fail. EditorASC (talk) 09:36, 16 March 2010 (UTC)
replies: text: " ... the need to keep cosmic radiation inflow to a minimum. Shoot me down if I'm wrong!" - sorry, you are wrong. As EditorASC writes, Concorde's windows were the size they were to limit the amount of cabin air escaping should a window break at 60,000 feet. In this case the aircraft would immediately slow down to below Mach 1 and begin an immediate descent, which would be very rapid as the aircraft was certified to use reverse thrust on two inner engines in flight, thus allowing a rate-of-descent of something like ten thousand feet per-minute. IIRC, after the initial Concorde design was completed the cabin pressurisation system was subsequently uprated in capacity to allow for the loss of a single window so enabling less rapid descents should a window fail. IIARC, the cabin windows themselves were triple-glazed, both for strength and for heat insulation, due to the outside skin temperature which was around 90C at Mach 2.— Preceding unsigned comment added by 95.149.173.74 (talk) 16:03, 16 May 2016 (UTC)

text: Perhaps if you read the Altimeter and Atmospheric pressure articles, you'd understand the relationship between air pressure and altitude (and hence how the former is derived from the latter, e.g. at El Alto International Airport)  Socrates2008 (Talk) 12:16, 16 March 2010 (UTC)
thread_title: small cabin windows

message: After doing a Google search for the FARs that limit operating altitude to FL400, this immediately came up: http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgPolicy.nsf/0/90AA20C2F35901D98625713F0056B1B8?OpenDocument
It outlines that they have a new interim policy that allows a service ceiling of FL450. This is a 2006 document, and this page hasn't been updated with this information yet. I would do it if I were more familiar with the FAR approval process, but if this is currently in effect the information on this wiki page would be outdated. Could someone who knows who the FAA works please check this? 94.210.18.219 (talk) 10:28, 20 September 2010 (UTC)
thread_title: New FAA Rules (FL400 max becomes FL450?)

message: I just had to revert a recent edit, because one editor inserted his comments in the middle of a paragraph that was written by another editor.  That is improper---comments by one editor should not be altered or broken up by another editor.  If one wants to comment on what another editor said, then copy it and show it as a quotation, to which you are responding.  It is NEVER proper to break up or alter what another editor said, on a Wiki TALK PAGE!  Only Administrators have the right to delete comments on Talk Pages, and then only for some violation of Talk Page posting rules.
Additionally, when quoting and then responding to what another editor said, it should be posted in the same section where the original quotation was posted.  It makes for serious confusion to the rest of us, if you post a response in one section, to statements made by another editor, in an entirely different section.  
Finally, any post should not cause the page to go way wide, i.e., your post should not force others to have to slide the page back and forth on the horizontal scale, to read it.  If you see that your post did that to the page, then you should correct it yourself right away.  Please do not leave messes for others to clean up.  Thanks for your consideration.  EditorASC (talk) 11:11, 16 March 2010 (UTC)
thread_title: Talk Page Rules

message: Bilcat removed the Notable incident tables!  Having recovered from the shock of that and accepting it reluctantly as the right decision, most of the rest of this section also needs to go for the same reason, it is redundant, being dealt with in Uncontrolled decompression and prone to contradiction. Ex nihil (talk) 01:13, 21 April 2010 (UTC)
thread_title: Loss of pressurization section

message: The "need for cabin pressurization" section doesn't make sense when it describes barotrama, because that section says that avoiding barotrama is one of the reasons that pressurizing flights is necessary, yet when it describes barotrama it only describes the symptoms of barotrama that people experience on pressurized flights. In contrast, the other three "illnesses" mentioned in that section appear to be described in terms of the symptoms that would be experienced on unpressurized flights above 3000 meters, which makes more sense in context.
While I think this information is important to present in some way and perhaps even expand on (i.e. many people experience ear pain from mild barotrama due to normal, controlled cabin pressure changes) the way it's presented in this section is strange.
69.181.161.106 (talk) 04:02, 6 January 2011 (UTC)
thread_title: BarotraUma

message: I am wondering if Wikipedia has any rules or guidelines about when and how to name the crew members on accident flights?  I have recently noticed that in some articles, no crew member names are given at all [here], and in other accidents, the full crew (both cockpit & cabin) are named [here], and in still others only the Captains and First Officers are named [here].  Is that disparity just the result of happenstance, as to who first writes an article, or is it by design?  It would be helpful for some of us IP editors if someone can explain if there are some specific guidelines to follow, on this aspect of aviation accident articles. Thank you, 66.81.52.230 (talk) 11:02, 23 October 2011 (UTC)
replies: text: More happenstance, depending on who wrote it and whether the source for the incident gave names. GraemeLeggett (talk) 13:46, 23 October 2011 (UTC)
replies: text: Thank you for that prompt response.  I surmise then that no one would object if I add crew members names in those articles that don't have them, if they where listed in the official accident reports. 66.81.52.253 (talk) 22:24, 23 October 2011 (UTC)
thread_title:  Wiki conventions for naming crew members in airliner accident articles 

message: I'm assuming that both the passenger cabin and the freight space on an airliner are pressurized. If so, there is an anomaly. Passenger doors open inwards to help ensure cabin pressure keeps the doors closed, but the undercarriage doors (undercarriage is often partly or completely retracted within the fuserlarge, esp nose wheel) open outwards creating a greater risk. It would also require the cabin to be depressurised before lowering undercarriage (not unreasonable). Is this right, or is the freight space not pressurised (the cabin floor looks to me to be stronger than the cabin wall)?    Presumably one of you experts know the answer and can add it to the article for completeness.FreeFlow99 (talk) 19:03, 15 November 2012 (UTC)
thread_title:  Pressurization of cargo space and doors. 

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thread_title:  Blacklisted Links Found on the Main Page 

message: I don't think this article explains the reason to use a cabin pressure less than sea level.  Does it really reduce stress on the airframe?  Is it to save weight (several hundred kilos)?  — Preceding unsigned comment added by 106.68.193.191 (talk) 03:03, 14 January 2016 (UTC)
replies: text: The key parameter here is the cabin differential - the difference between the pressure inside the fuselage and atmospheric pressure outside the fuselage. The stress in the skin of the fuselage is determined by the cabin differential and the thickness of the skin. If a pressurized aircraft is designed and approved for a high cabin differential it must have thick skins, or skins made of stronger material than would be the case if it was designed and approved for a low cabin differential. So a compromise is required by the designer - does he select a high cabin differential for maximum passenger comfort and bear the cost of heavier weight or more expensive material; or does he select a low cabin differential for a lighter weight or less expensive material? A relevant consideration is that cabin altitudes less than about 8,000 feet cause no risk or discomfort to the great majority of able-bodied passengers. Do you think these considerations are adequately explained in the article? Dolphin (t) 07:41, 14 January 2016 (UTC)
thread_title:  Reason for pressurization to be less than sea level pressure. 

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thread_title:  External links modified 

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message: In the introduction, the article appears to mis-state the cause of the Aloha 243 incident. There was no pre-existing Boeing design limitation on number of cycles that the airframe was designed to endure. Boeing and Aloha both knew the cycles the aircraft had accumulated, and it was not out of specification. Rather, poor inspection and maintenance of the fuselage was the cause, which would have detected the fatigue cracks. If there is no objection, I will delete the Aloha 243 sentence from the introduction. --Westwind273 (talk) 16:39, 3 March 2022 (UTC)
thread_title:  Aloha 243 cause