Place the oxygen mask on yourself first before assisting others.

July 23, 2016 11:52 AM

Alright sir, if you don't get on oxygen you're going to die. [YT] Destin Sandlin of "Smarter Every Day" goes into a high altitude simulation chamber where he demonstrates why you should definitely, always, put on your own oxygen mask first. The chamber is set to the equivalent of 25,000 feet (7,620 meters) after a slow decompression, which allows 3 to 5 minutes of consciousness. The video points out that "most airliners travel at 35,000 feet" (10,670 meters), and under a real scenario you may get only 15-30 seconds of useful consciousness.
posted by zennie (32 comments total)

you may get only 15-30 seconds of useful consciousness

Thank the Lord for small mercies...
posted by acb at 12:11 PM on July 23, 2016

I feel smarter already. Thanks for this post!
posted by heyho at 12:15 PM on July 23, 2016 [1 favorite]

This is a heck of a thing. A compelling video to see how mentally paralyzed he was when they told him to put his own mask back on once his O2 saturation got dangerously low.
posted by chimaera at 12:16 PM on July 23, 2016 [7 favorites]

My favorite demonstration of this: 4 of spades.
posted by teraflop at 12:19 PM on July 23, 2016 [25 favorites]

Wait a sec. When he was a kid he got to go in a NASA low-gravity simulator? I'm so jealous right now! :(
posted by the agents of KAOS at 12:24 PM on July 23, 2016 [3 favorites]

Scary stuff. A similar cognitive impairment, nitrogen narcosis, kills even well-trained scuba divers if they make a few bad judgment calls.

It's pretty terrifying how one error can impair your judgement enough to make a second error, and then a deadly cascade begins.
posted by leotrotsky at 12:36 PM on July 23, 2016 [4 favorites]

I've worn an oxygen mask in flight once, but that was because (I'm pretty sure) the cabin wasn't pressurized.

It was a small flight in Peru, from Cuzco to Lima, and we didn't go too high, but high enough that oxygen was provided. Some of the other passengers, who looked like they took this kind of flight often enough, didn't bother with the masks, but others did. No one told us to put on the masks, but my brother looked over at our mom and said "Mom, your lips are turning blue." After putting on the masks, we were suddenly a lot more alert, and realized how impaired our thoughts had become. The passengers who didn't put on masks just rested for a while, since it was a short flight.

And it sounds like surviving a plane crash is a lot more likely than I imagined:

The NTSB says that despite more people flying than ever, the accident rate for commercial flights has remained the same for the last two decades, and the survivability rate is a high 95.7 percent.

The European Transport Safety Council (ETSC) has also examined the survivability of aircraft accidents worldwide, estimating that 90 percent are survivable (no passengers died) or “technically survivable," where at least one occupant survives. Most of those fatalities were a result of impact and fire-related factors including smoke inhalation after impact.

So put on those oxygen masks when you need to.
posted by filthy light thief at 12:41 PM on July 23, 2016 [5 favorites]

My favorite demonstration of this: 4 of spades.

Holy smokes. It's like his brain and body got stuck on the last thing he did and he's literally doomed to repeat it until he dies.
posted by zennie at 12:42 PM on July 23, 2016 [2 favorites]

Wow, these (the FPP and the 4 of spades) are really striking.
posted by LobsterMitten at 12:44 PM on July 23, 2016 [1 favorite]

Wow, this was a really stark demonstration. If you're on the fence about watching this, DO IT.
posted by obfuscation at 1:01 PM on July 23, 2016 [3 favorites]

Here's a recording of a discussion between air traffic control and a pilot who doesn't realize he's suffering from hypoxia.
posted by NotMyselfRightNow at 1:30 PM on July 23, 2016 [19 favorites]

I've climbed to 23,000 feet without oxygen, but that was after a couple weeks of acclimatization. You can compensate for the lower pressure somewhat by breathing faster and more forcefully.

These test subjects could have improved their condition simply by consciously breathing harder. The issue with high altitude hypoxia is that the nervous system's feedback loop does not respond properly to the changes in oxygen and carbon dioxide in the blood that normally regulate breathing. Notice that the test subjects were breathing slowly and normally even though their blood oxygen level was similar to having finished an anaerobic sprint that should leave you panting. When unacclimatized, you have to consciously tell yourself to breath harder.

This can become a real problem for sleeping at high altitude. Some people while sleeping literally stop breathing for up to two minutes at a time, then suddenly wake up and start panting, then fall asleep and stop breathing again. The feedback loop for the oxygen and carbon dioxide sensors gets 180 degrees out of phase and leads to an oscillation.

Drugs like Diamox (sometimes called the climbers sleeping pill) can change the acidity of the blood to improve the nervous feedback mechanism and promote more rapid and even breathing at altitude.
posted by JackFlash at 2:21 PM on July 23, 2016 [7 favorites]

This is fascinating and disturbing.
posted by the thought-fox at 2:38 PM on July 23, 2016 [1 favorite]

Oxygen starvation during his flight to Britain nearly did in Niels Bohr.
posted by phooky at 3:34 PM on July 23, 2016

The best option to maximize your chances of walking away from a plane crash is to sit up the rear end of the plane, according to crash test results conducted by scientists for Discovery TV last year.

You know the "crumple zone" on well designed cars? Well the entire plane is the crumple zone for us back seat flyers. Oh and wear leather shoes, sneakers are so much more comfortable but, ah, melt in certain situations.
posted by sammyo at 3:46 PM on July 23, 2016 [2 favorites]

If I remember correctly a pilot and aircraft were lost because the pilot had the visor of his pressure suit open inside the normally pressurized cockpit of an SR-71 spyplane, (I might have it confused with a U-2,) he lost consciousness before he could lower the visor. Subsequent flights the visors had to be closed for the entire flight.
posted by Pembquist at 4:29 PM on July 23, 2016

These test subjects could have improved their condition simply by consciously breathing harder.

I don't disagree, but I think that misses two important points.

First, climbers know they're slowly going higher, into lower-oxygen environment, and can find ways to compensate. Pilots, and passengers, either end up there in an instant due to catastrophic failures, or get there completely unaware when there's an aircraft failure (broken seal, etc.). In the first case, breathing harder likely isn't going to work fast enough, and in the second case, they simply don't know they need to.

Second, part of the training in that video is to learn the symptoms that are specific to the individual, so they can learn to react earlier rather than later in an aircraft malfunction scenario. Teaching them to find ways to overcome it, while likely helpful overall, do nothing to help them learn the symptoms to watch for.
posted by NotMyselfRightNow at 4:42 PM on July 23, 2016 [3 favorites]

It was kinda disturbing seeing him hear: ... Or your gonna die. And he responds "I don't want to die" and sits there grinning like a golden retriever.
posted by wotsac at 4:50 PM on July 23, 2016 [11 favorites]

Fun fact: passenger aircraft pressurization in flight is controlled by 1) the air conditioning packs pumping air into the cabin and 2) a big hole in the fuselage with a movable flap to control the outflow. How can you pressurize the fuselage if there's a hole? Good physics question. Say you close the valve and pressurized the tube. Now if you opened it suddenly, how long would it take for all that air to rush out? There must be some physical scale that sets this speed---it's probably not the speed of light, and ideal gases don't have viscosity, so what's left? The speed of sound. The air can only go as fast as the speed of sound on its escape from the outflow valve, thus setting the mass outflow rate and in turn the rate that the air conditioning has to pump air in to keep the aircraft pressurized.
posted by kiltedtaco at 5:08 PM on July 23, 2016 [10 favorites]

Here's a recording of a discussion between air traffic control and a pilot who doesn't realize he's suffering from hypoxia

"Unable to control altitude. Unable to control airspeed. Unable to control heading. Other than that, everything A-OK!"

(said like he really means it!)
posted by atoxyl at 5:35 PM on July 23, 2016 [5 favorites]

I'm surprised how long the guy in the control room let him go on without ordering someone to put his mask on for him. Christ, I was practically yelling at the screen by that point.
posted by alidarbac at 6:20 PM on July 23, 2016

It's disturbing that, even if you are aware of what's happening to you, knowing that seems to do you no good at all.
posted by thelonius at 6:38 PM on July 23, 2016 [1 favorite]

Yawn at the guys in the hyperbaric chamber, but the video of the in-flight hypoxia was absolutely terrifying. Aint got no flight surgeons up there.
posted by iffthen at 3:21 AM on July 24, 2016

I have an unpressurized plane and will check myself and passengers with pulse oximeters above around 9000 feet. My goal is to keep above 90% saturation which I can do easily without supplemental oxygen below about 11,000 feet. If I'm planning a flight at higher altitudes, I will carry oxygen equipment with nasal cannula. I think around the 80-85% range will start to produce insidious issues with decision making, etc. I'm surprised that this guy had any faculties left in the 60-70% range, but I guess he was only at that level for a moment. Apparently 90% is a standard for medical intervention (PDF, just a link I found trying to support something I'd heard).

JackFlash: "Drugs like Diamox (sometimes called the climbers sleeping pill) can change the acidity of the blood to improve the nervous feedback mechanism and promote more rapid and even breathing at altitude"

It also causes a very strange side effect, making carbonated beverages seem flat and uncarbonated.
posted by exogenous at 5:06 AM on July 24, 2016 [10 favorites]

I did high altitude training like this at Beale Air Force base a few years ago. The place they train U-2 pilots. We were just a group of civilian pilots borrowing their hypobaric training because it seemed like fun. Turns out to be terrifying.

There's a collection of hypoxia symptoms people exhibit. The interesting thing is different people have different symptoms, but each individual has the same symptom first every time. We were encouraged to learn what ours was, to recognize the hypoxia, so we could quickly fix it in a real emergency.

My symptom turns out to be tunnel vision. Like all of us in the training, I intended to stay without the mask as long as I could, knowing I'd be safe and wanting the full experience of it. That bravado lasted about 4 seconds, right until my vision collapsed to a narrow tunnel. I was sure I was having a stroke. On went the mask, vision restored, and boy was that an effective demonstration.

One of the other guys in our group was kind of a jerk. He was always telling people how great a pilot he was and then making dumb, unsafe mistakes. Without oxygen he just got worse, more and more belligerent and convinced of his own capability despite obviously being completely fucked up from hypoxia. He went a good .. 45? seconds of angrily telling everyone he didn't need any oxygen. Mind you 20 seconds into this he has a very forceful air force guy in his face saying over and over "put on the mask, sir. put on the mask sir". He kept refusing until he started to actually pass out and, to his credit, managed to fumble the mask on. In a real emergency his belligerence might well have gotten himself and his passengers killed.
posted by Nelson at 10:49 AM on July 24, 2016 [11 favorites]

In a real emergency his belligerence might well have gotten himself and his passengers killed.

Yeah that is a personality type that is a real drag in aviation and elsewhere.

My favorite story about hypoxia is from a pilot recounting his brush with eternity. He said he felt real good and started thinking "hey, I bet it could make it to the next field instead of landing." When he got over that field he felt so good he thought why not try for the next one, and again "I bet I've got just enough fuel to make it one more leg," at some point on his way to running out of gas he descended, came to his senses, freaked out and landed immediately. It was a very real example of "WHAT WAS I THINKING?" For some reason his oxygen deprived brain thought it would be really cool to just barely make it to landing.
posted by Pembquist at 12:15 PM on July 24, 2016 [1 favorite]

I should figure out how to get in on some of that hypoxia training. I regularly use closed-circuit rebreathers for both research and recreational purposes and the danger of hypoxia is real, given certain failure modes of the units we use. It's especially insidious since air hunger comes from CO2 buildup rather than O2 deprivation, so with a system where the CO2 is chemically scrubbed (true for rebreathers, space station, and many aircraft too I think) you can go hypoxic without feeling starved for air.

I think this video will be a great training aid.
posted by deadbilly at 2:03 PM on July 24, 2016 [1 favorite]

I have pernicious anemia, and by the time I was diagnosed after a steady decline over about 2.5 months to a state that felt almost stable, I was down to a hematocrit of 10 (as measured by 3 independent labs because my hematologist refused to believe it), and since 40 is the low end of of normal, that would seem to suggest I was at the functional equivalent of 25% oxygen saturation for a normal man.

I was still moving around, doing things and making decisions, most all of them bad, but I was floating weightlessly through life, and my emotions were pallid, milling ghosts of themselves twice removed.

Recently I was pretty upset about some things, and I wondered how much that state of diaphanous and insubstantial emotion was an adaptation, and whether I could partially reclaim it to calm myself. So I sat down, cast my mind back to that time, and before I knew it, I experienced a sensation like the cool flow of anesthetic into my veins that I remembered from lying on the operating table before some of my surgeries -- but when the lights started to dim, I panicked and came out of it, and I haven't tried it again.

So I think it might be possible, probably by dint of training no one in their right mind would want to go through, to adapt to surprisingly low oxygen concentrations without losing consciousness, but it might not be terribly useful.

Diamox is a carbonic anhydrase inhibitor, and I would say it's likely that it helps you in thin air mainly by reducing your body's normal demand for carbon dioxide, thereby increasing its concentration in your blood, which in turn makes you breathe faster and harder. And I would try to explain exogenous's observation that Diamox makes "carbonated beverages seem flat and uncarbonated" as due to Diamox raising the CO₂ level in tissues so high that carbonation no longer has its normal 'bite'.
posted by jamjam at 2:08 PM on July 24, 2016 [4 favorites]

If I understand that article I linked about hypoxia correctly, the hypoxia that comes from a rapid decompression of an aircraft is a different thing than simply being oxygen starved because you're at high altitude or have some slow process depriving you of oxygen. As the article notes, "there is an immediate reversal of oxygen flow from the blood to the lung within four to five seconds following the decompression."

It sounds like in rapid decompression the oxygen is being removed from your blood immediately; sort of breathing in reverse. That must explain why the onset of symptoms was so fast in the altitude training I did. It didn't feel like I'd held my breath for 2 minutes and was getting a headache. It was like suddenly my brain just didn't work.
posted by Nelson at 12:27 AM on July 25, 2016 [1 favorite]

If you have a pilots license and happen to find yourself in Oklahoma City, the FAA tech center there offers free hypoxia training. I think they recommend not flying for a day or two afterwards.

The drop-down masks on commercial airliners are connected to oxygen candles, which provide around a half hour of breathing air. The Air Force plane I used to work on carries a giant dewer of liquid oxygen in the aft cargo compartment. The plane was designed for Cold War missions, so even without pressurization the crew was supposed to be able to complete their mission (loitering over the Arctic Circle waiting for incoming Soviet bombers) for something like 20 hours before being relieved.
posted by backseatpilot at 7:36 AM on July 25, 2016 [1 favorite]

Jesus, that Four of Spades video is terrifying.
posted by Johnny Wallflower at 10:20 PM on July 30, 2016

The forthcoming book The Crash Detectives, by Christine Negroni includes a fair bit about hypoxia as contributory or the cause of certain plane crashes, including her theory on Malaysia Airlines Flight MH370 (I've been reading an uncorrected proof; very interesting so far).
posted by gudrun at 9:54 AM on August 1, 2016 [1 favorite]