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*[[Altitude sickness]].
*[[Frostbite]] or [[hypothermia]] from exposure to [[Troposphere#Temperature|freezing cold air]] at high altitude.<ref>{{Cite journal|last1=Daidzic|first1=Nihad E.|last2=Simones|first2=Matthew P.|date=March{{ndash}}April 2010|title=Aircraft Decompression with Installed Cockpit Security Door |url=https://doi.org/10.2514/1.41953|journal=Journal of Aircraft|volume=47|issue=2|pages=490–504|doi=10.2514/1.41953|quote=<!-- page 490, col. 2-->[A]t 40,000 ft (12,200 m), the [[International Standard Atmosphere]] (ISA) pressure is only about 18.8 kPa (2.73 psi), and the air temperatures are about '''−56.5{{nbsp}}°C (217{{nbsp}}K)'''. The [[Boiling point|boiling temperature]] of water at this atmospheric pressure is about''' −59{{nbsp}}°C (332{{nbsp}}K)'''. Above 63,000 ft or 19,200 m ([[Armstrong limit|Armstrong line]]), the ISA environmental pressure drops below 6.3 kPa (0.91 psi) and the boiling temperature of water reaches the normal human body temperature (about 37 C). Any prolonged exposure to such an environment could lead to [[ebullism]], anoxia, and ultimate death, after several minutes. These are indeed very hostile conditions for human life.
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* [[Physical trauma]] caused by the violence of explosive decompression, which can turn people and loose objects into projectiles.
At least two confirmed cases have been documented of a person being blown through an airplane passenger window. The first [[National Airlines Flight 27|occurred in 1973]] when debris from an [[Turbine engine failure|engine failure]] struck a window roughly midway in the fuselage. Despite efforts to pull the passenger back into the airplane, the occupant was forced entirely through the cabin window.<ref name="auto2">{{cite web|last=Mondout |first=Patrick |title=Curious Crew Nearly Crashes DC-10 |url=http://www.super70s.com/Super70s/Tech/Aviation/Disasters/73-11-03%28National%29.asp |access-date=2010-11-21 |url-status=dead |archive-url=https://web.archive.org/web/20110408023924/http://www.super70s.com:80/super70s/tech/aviation/disasters/73-11-03(National).asp |archive-date=2011-04-08 }}</ref> The passenger's skeletal remains were eventually found by a construction crew, and were positively identified two years later.<ref name="auto1">{{cite news |last=Harden |first=Paul |title=Aircraft Down |url=http://www.dchieftain.com/news/aircraft-down/article_23a78c5b-7d34-5684-89ee-0f0a5de0c513.html |access-date=2018-10-24 |newspaper=El Defensor Chieftain |date=2010-06-05 |archive-date=2019-10-17 |archive-url=https://web.archive.org/web/20191017132530/http://www.dchieftain.com/news/aircraft-down/article_23a78c5b-7d34-5684-89ee-0f0a5de0c513.html |url-status=dead }}</ref> The second incident occurred on April 17, 2018, when a woman on [[Southwest Airlines Flight 1380]] was partially blown through an airplane passenger window that had broken from a similar engine failure. Although the other passengers were able to pull her back inside, she later died from her injuries.<ref name="auto">{{cite web|url=https://www.foxnews.com/us/southwest-airlines-planes-engine-explodes-1-passenger-dead/|title=Southwest Airlines plane's engine explodes; 1 passenger dead|first=Kathleen|last=Joyce|website=[[Fox News]]|date=April 17, 2018}}</ref><ref name="nbcphiladelphia.com1">{{Cite web|url=https://www.nbcphiladelphia.com/news/national-international/airplane-makes-emergency-landing-at-philadelphia-international-airport/52411/|title=Woman Partially Sucked Out of Jet When Window Breaks Mid-Flight; Plane Makes Emergency Landing in Philadelphia|first1=Vince|last1=Lattanzio|first2=Alicia Victoria|last2=Lozano|first3=Denise|last3=Nakano|first4=Brian X.|last4=McCrone • •|date=17 April 2018 }}</ref><ref name="NYT on passenger">{{cite news|last1=Stack|first1=Liam|last2=Stevens|first2=Matt|title=A Southwest Airlines Engine Explodes, Killing a Passenger|url=https://www.nytimes.com/2018/04/17/us/southwest-airlines-explosion.html|access-date=April 18, 2018|work=[[The New York Times]]|date=April 17, 2018}}</ref> In both incidents, the plane landed safely with the sole fatality being the person seated next to the window involved.
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Cabin doors are designed to prevent losing cabin pressure through them by making it nearly impossible to open them in flight, whether accidentally or intentionally. The [[plug door]] design ensures that when the pressure inside the cabin exceeds the pressure outside, the doors are forced shut and will not open until the pressure is equalized. Cabin doors, including the emergency exits, but not all cargo doors, open inwards, or must first be pulled inwards and then rotated before they can be pushed out through the door frame because at least one dimension of the door is larger than the door frame. Pressurization prevented the doors of [[Saudia Flight 163]] from being opened on the ground after the aircraft made a successful emergency landing, resulting in the deaths of all 287{{nbs}}passengers and 14{{nbs}}crew members from fire and smoke.
Prior to 1996, approximately 6,000{{nbs}}large commercial transport airplanes were [[type certificate|type certified]] to fly up to {{convert|45000|ft}}, without being required to meet special conditions related to flight at high altitude.<ref>{{Cite web|url=https://rgl.faa.gov/|title=RGL Home Page|website=rgl.faa.gov|access-date=2022-11-06|archive-date=2022-12-14|archive-url=https://web.archive.org/web/20221214143433/https://rgl.faa.gov/|url-status=dead}}</ref> In 1996, the FAA adopted Amendment 25–87, which imposed additional high-altitude cabin-pressure specifications, for new designs of aircraft types.<ref name="FAA_25.841">{{cite web|url=http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/FED94F31539484AB852566720051AA5D?OpenDocument|title=Section 25.841: Airworthiness Standards: Transport Category Airplanes|publisher=[[Federal Aviation Administration]]|date=1996-05-07|access-date=2008-10-02|archive-date=2009-02-02|archive-url=https://web.archive.org/web/20090202140424/http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/FED94F31539484AB852566720051AA5D?OpenDocument|url-status=dead}}</ref> For aircraft [[type certificate|certified]] to operate above 25,000 feet (FL 250; 7,600 m), it "must be designed so that occupants will not be exposed to cabin pressure altitudes in excess of {{convert|15000|ft}} after any probable failure condition in the pressurization system."<ref name="FARs, 14 CFR, Part 25, Section 841">{{Cite web|url=http://www.flightsimaviation.com/data/FARS/part_25-841.html|title=Flightsim Aviation Zone - Number 1 Flight Simulation & Aviation Resource! - Flight Simulator, Aviation Databases|website=www.flightsimaviation.com}}</ref> In the event of a decompression which results from "any failure condition not shown to be extremely improbable," the aircraft must be designed so that occupants will not be exposed to a cabin altitude exceeding {{convert|25000|ft}} for more than 2{{nbs}}minutes, nor exceeding an altitude of {{convert|40000|ft}} at any time.<ref name="FARs, 14 CFR, Part 25, Section 841"/> In practice, that new FAR amendment imposes an operational [[Ceiling (aeronautics)|ceiling]] of 40,000{{nbs}}feet on the majority of newly designed commercial aircraft.<ref name="Exemption No. 8695">{{cite web|url=http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgEX.nsf/0/9929ce16709cad0f8625713f00551e74/$FILE/8695.doc|title=Exemption No. 8695|publisher=[[Federal Aviation Administration]]|date=2006-03-24|___location=Renton, Washington|access-date=2008-10-02|archive-date=2009-03-27|archive-url=https://web.archive.org/web/20090327094608/http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgEX.nsf/0/9929ce16709cad0f8625713f00551e74/$FILE/8695.doc|url-status=dead}}</ref><ref>{{cite web|url=http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgPolicy.nsf/0/90AA20C2F35901D98625713F0056B1B8?OpenDocument|publisher=[[Federal Aviation Administration]]|date=2006-03-24|title=PS-ANM-03-112-16|access-date=2009-09-23|author=Steve Happenny|archive-date=2011-10-22|archive-url=https://web.archive.org/web/20111022084743/http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgPolicy.nsf/0/90AA20C2F35901D98625713F0056B1B8?OpenDocument|url-status=dead}}</ref>
In 2004, [[Airbus]] successfully petitioned the FAA to allow cabin pressure of the [[Airbus A380|A380]] to reach {{convert|43000|ft}} in the event of a decompression incident and to exceed {{convert|40000|ft}} 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.<ref name="Exemption No. 8695"/>
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==Notable decompression accidents and incidents==
Decompression incidents are not uncommon on military and civilian aircraft, with approximately 40–50 rapid decompression events occurring worldwide annually.<ref>{{cite web |url=http://www.amsanz.org.nz/avmedia/24/am24_2Decompression.pdf |title=Rapid Decompression In Air Transport Aircraft |date=2000-11-13 |access-date=2008-09-01 |publisher=Aviation Medical Society of Australia and New Zealand |url-status=dead |archive-url=https://web.archive.org/web/20100525193501/http://www.amsanz.org.nz/avmedia/24/am24_2Decompression.pdf |archive-date=2010-05-25 }}</ref> However, in most cases the problem is manageable, injuries or structural damage rare and the incident not considered notable.<ref name="AirQuality">{{cite book|title=Air Quality in Airplane Cabins and Similar Enclosed Spaces |author1=Martin B. Hocking |author2=Diana Hocking |url=https://books.google.com/books?id=KzXPJ-p75QIC |isbn=3-540-25019-0|publisher=Springer Science & Business|year=2005|access-date=2008-09-01}}</ref> One notable
Decompression incidents do not occur solely in aircraft; the [[Byford Dolphin]] accident is an example of violent explosive decompression of a [[saturation diving]] system on an [[Oil platform|oil rig]]. A decompression event is often the result of a failure caused by another problem (such as an explosion or mid-air collision), but the decompression event may worsen the initial issue.
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| [[Ilyushin Il-76]]
| Accident
| Unknown{{efn|The number of passengers aboard Ilyushin Il-76 ranged from 160 to 350+. Depending on the source there were 17 to 200 survivors.}}
| Explosive decompression
| Rear loading ramp disintegration from aircraft while cruising leading to explosive decompression
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| {{ntsh|0}}4/4
| Gradual decompression
| Under investigation
|-
| [[2023 Virginia Cessna Citation crash]]
|[[Alaska Airlines Flight 1282]]▼
| 2023
|2024▼
| [[Cessna Citation V]]
|[[Boeing 737 MAX|Boeing 737 MAX 9]]▼
| Accident
| {{ntsh|0}}4/4
|0/177▼
|
| Inconclusive; possibly incomplete maintenance{{efn|While incomplete maintenance was a factor, the NTSB was unable to determine what could have caused the aircraft to depressurize.}}
|Door plug failure; under investigation.<ref name="seattletimeshole">{{Cite news |last=Gates |first=Dominic |author-link=Dominic Gates |date=January 5, 2024 |title=Alaska Airlines grounds MAX 9s after door plug blows out on Portland flight |url=https://www.seattletimes.com/business/180-on-alaska-airlines-flight-safe-and-scared-in-portland-after-window-blows/ |url-status=live |archive-url=https://web.archive.org/web/20240107200534/https://www.seattletimes.com/business/180-on-alaska-airlines-flight-safe-and-scared-in-portland-after-window-blows/ |archive-date=January 7, 2024 |access-date=January 6, 2024 |work=The Seattle Times}}</ref>▼
|-
▲| [[Alaska Airlines Flight 1282]]
▲| 2024
▲| [[Boeing 737 MAX|Boeing 737 MAX 9]]
| Accident
▲| 0/177
| Explosive decompression
▲| Door plug failure; under investigation.<ref name="seattletimeshole">{{Cite news |last=Gates |first=Dominic |author-link=Dominic Gates |date=January 5, 2024 |title=Alaska Airlines grounds MAX 9s after door plug blows out on Portland flight |url=https://www.seattletimes.com/business/180-on-alaska-airlines-flight-safe-and-scared-in-portland-after-window-blows/ |url-status=live |archive-url=https://web.archive.org/web/20240107200534/https://www.seattletimes.com/business/180-on-alaska-airlines-flight-safe-and-scared-in-portland-after-window-blows/ |archive-date=January 7, 2024 |access-date=January 6, 2024 |work=The Seattle Times}}</ref>
|}
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In 2004, the TV show ''[[MythBusters]]'' examined whether explosive decompression occurs when a bullet is fired through the fuselage of an airplane [[MythBusters (2004 season)#Explosive Decompression|informally]] by way of several tests using a decommissioned pressurised DC-9. A single shot through the side or the window did not have any effect – it took actual explosives to cause explosive decompression – suggesting that the [[fuselage]] is designed to prevent people from being blown out.<ref>{{cite magazine|url=https://newsfeed.time.com/2011/04/05/southwests-scare-when-a-plane-decompresses-what-happens/|title=Southwest's Scare: When a Plane Decompresses, What Happens?|magazine=Time|author=Josh Sanburn|date=April 5, 2011|access-date=April 18, 2018}}</ref> Professional pilot David Lombardo states that a bullet hole would have no perceived effect on cabin pressure as the hole would be smaller than the opening of the aircraft's [[Cabin pressurization#Mechanics|outflow valve]].<ref>{{cite web|url=https://www.stuff.co.nz/travel/travel-troubles/103194084/the-deadly-result-when-a-large-hole-is-ripped-in-the-side-of-an-aircraft|title=The deadly result when a large hole is ripped in the side of an aircraft|work=www.stuff.co.nz|author=Michael Daly and Lorna Thornber|date=April 18, 2018|access-date=April 18, 2018}}</ref>
However, [[NASA]] scientist [[Geoffrey A. Landis]] points out
===Exposure to a vacuum causes the body to explode===
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The first type is more common as pressure reduction from normal atmospheric pressure to a vacuum can be found in both space exploration and high-altitude [[aviation]]. Research and experience have shown that while [[Effect of spaceflight on the human body#Space environments|exposure to a vacuum]] causes swelling, [[skin|human skin]] is tough enough to withstand the drop of one [[atmosphere (unit)|atmosphere]].<ref name="Barratt">{{cite web|url=http://www.uh.edu/engines/epi2691.htm|title=No. 2691 THE BODY AT VACUUM|work=www.uh.edu|author=Michael Barratt|access-date=April 19, 2018|author-link=Michael Barratt (astronaut)}}</ref><ref name="Kruszelnicki">{{cite web|url=http://www.abc.net.au/science/articles/2005/04/07/1320013.htm|title=Exploding Body in Vacuum|publisher=[[ABC News (Australia)]]|author=Karl Kruszelnicki|date=April 7, 2005|access-date=April 19, 2018|author-link=Karl Kruszelnicki}}</ref> The most serious risk from vacuum exposure is [[Hypoxia (medical)|hypoxia]], in which the body is starved of [[oxygen]], leading to unconsciousness within a few seconds.<ref name="FAA" >{{cite web|title=Advisory Circular 61-107 |url=http://www.faa.gov/pilots/training/airman_education/media/AC%2061-107A.pdf|pages=table 1.1|publisher=[[FAA]] }}</ref><ref>{{cite book|title=Flight Surgeon's Guide|chapter-url=http://wwwsam.brooks.af.mil/af/files/fsguide/HTML/Chapter_02.html|chapter=2|publisher=[[United States Air Force]]|url-status=dead|archive-url=https://web.archive.org/web/20070316011544/http://wwwsam.brooks.af.mil/af/files/fsguide/HTML/Chapter_02.html|archive-date=2007-03-16}}</ref> Rapid uncontrolled decompression can be much more dangerous than vacuum exposure itself. Even if the victim does not hold their breath, venting through the windpipe may be too slow to prevent the fatal rupture of the delicate [[Pulmonary alveolus|alveoli]] of the [[lung]]s.<ref name="harding">{{Cite book | last1=Harding | first1=Richard M. | year=1989 | title=Survival in Space: Medical Problems of Manned Spaceflight | place=London | publisher=Routledge | isbn=0-415-00253-2 | url=https://archive.org/details/survivalinspacem0000hard }}</ref> [[Eardrum]]s and sinuses may also be ruptured by rapid decompression, and soft tissues may be affected by bruises seeping blood. If the victim somehow survived, the stress and shock would accelerate oxygen consumption, leading to hypoxia at a rapid rate.<ref name=czarnik>{{cite web |author=Czarnik, Tamarack R. |year=1999 |title=Ebullism at 1 Million Feet: Surviving Rapid/Explosive Decompressionn |url=http://www.geoffreylandis.com/ebullism.html |access-date=2009-10-26 }}</ref> At the extremely low pressures encountered at altitudes above about {{convert|63000|ft|m|-3}}, the boiling point of water becomes less than normal body temperature.<ref name="Barratt"/> This measure of altitude is known as the [[Armstrong limit]], which is the practical limit to survivable altitude without pressurization. Fictional accounts of bodies exploding due to exposure from a vacuum include, among others, several incidents in the movie ''[[Outland (film)|Outland]]'', while in the movie ''[[Total Recall (1990 film)|Total Recall]]'', characters appear to suffer effects of [[ebullism]] and blood boiling when exposed to the [[atmosphere of Mars]].
The second type is rare since it involves a pressure drop over several atmospheres, which would require the person to have been placed in a pressure vessel. The only likely situation in which this might occur is during decompression after deep-sea diving. A pressure drop as small as 100 Torr (13 kPa), which produces no symptoms if it is gradual, may be fatal if it occurs suddenly.<ref name="harding" /> [[Byford Dolphin#
== See also ==
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==Notes==
{{notelist}}
==References==
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[[Category:Aviation medicine]]
[[Category:Underwater diving medicine]]
[[Category:Underwater diving hazards]]
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