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I just read Mayday by Nelson Demille. I won't get into many details but the book talks about an airliner (similar to the Concorde) which operates at an altitude of ~60,000 ft (~18Km). Suddenly, due to a mistaken missile launch, there are holes on both sides of the plane. All the passengers become brain-damaged except 5 people who are trapped in lavatories at that time.

Now while this is fiction, could we go crazy due to lack of oxygen in case something goes wrong? How much oxygen would be needed to land safely and how much oxygen is usually kept on an airliner in case of emergencies.

A second and related question: in case of a fire or other incident, how quickly can a plane safely descend? I know and have experienced losing altitude the last 30 minutes or so of flight, probably lining up to the airport. In an emergency, how quickly can the pilot land? Is it 5-10 minutes or more? I am talking about descending from cruise altitude and come to a dead-stop.

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  • $\begingroup$ I've made some edits, based on the book description at Amazon. Feel free to roll them back if you feel it changes the basic question in any way. $\endgroup$ – aeroalias Dec 16 '16 at 0:05
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    $\begingroup$ @aeroalias edited it bit more. The book says 60,000 ft so sticking with that. Also saw that the concode flew at 58k aviation.stackexchange.com/questions/16014/… hence sticking with the fantasy :) $\endgroup$ – shirish Dec 16 '16 at 0:10
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    $\begingroup$ You have a few different questions bundled here. See here for depressurization; here for the O2 system; and here for emergency descent. All of those questions have other relevant and interesting ones linked to them. $\endgroup$ – Pondlife Dec 16 '16 at 0:17
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    $\begingroup$ From a Wikipedia article on "Cloud Suck": On 14 February 2007 while practising for a paragliding contest in Australia, Polish-born German team pilot Ewa Wiśnierska-Cieślewicz was sucked into a cumulonimbus cloud, climbing at up to 20 m per second (4,000 feet per minute) to an altitude of 9,946 m (32,600 feet). She lost consciousness due to hypoxia, but regained consciousness after 30 minutes to an hour, and landed still covered in ice after a three and a half hour flight. $\endgroup$ – Steve Dec 16 '16 at 15:23
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    $\begingroup$ Depending on meals and gastrointestinal conditions explosive decompression is certainly a risk inside lavatories as well. $\endgroup$ – Rob Vermeulen Dec 18 '16 at 15:21
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Long term, no, it is not. Any exposure to pressure altitudes over 26,000 ft will eventually cause death from hypoxia, even with acclimation to the higher altitudes. There is a period referred to as Time Of Useful Consciousness (ToC) associated with hypoxia. This is the approximate time that a healthy adult human with good lung capacity can maintain cognitive function. These values can be halved if an explosive decompression occurs, which is why there is a requirement that airliners have quick donning, pressure breathing oxygen masks available to the flight crew and can be donned and establish the flow of oxygen within 5 seconds. It is also the reason that flight attendants tell passengers to first don their emergency O2 masks, then assist someone else next to them in the event the masks are deployed.

Once ToC lapses at a given pressure altitude, cognitive function rapidly begins to fade away. The person becomes listless, sleepy, but often euphoric. Loss of consciousness, coma and then finally death will ensue unless the minimum partial pressure of O2 in the lungs is re-established.

Section 3-1 of the FAA Manual of Aviation Physiology is a good reference on the subject of hypoxia.

At the altitudes that Concorde cruised at, the air pressure is so low that decompression sickness becomes more of a risk than hypoxia. Having the water boil away in your own bloodstream is a very painful way to die, and loss of consciousness via hypoxia would almost be a relief from that torment.

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  • $\begingroup$ Water in bloodstream won't boil even in vacuum. The diastolic blood pressure in healthy human is around 80 mmHg and at that value, boiling point is still 47°C, safely above your body temperature. … $\endgroup$ – Jan Hudec Dec 19 '16 at 20:26
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    $\begingroup$ … Your body will swell everywhere, content of your digestive tract will expand uncomfortably and above 63,000 ft, where boiling point of water at ambient pressure drops below body temperature, your eyes and mucous membranes will quickly dry out, but it's always the hypoxia that is fatal. $\endgroup$ – Jan Hudec Dec 19 '16 at 20:26

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