Would you be concious if you fell from a plane?

August 17, 2005 10:55 AM

This has been bothering me for quite some time so any help would be greatly appreciated. I've often heard that when one falls from a great distance (say out of an airplane or off a building) with no parachute, they will pass out in short order. I'm wondering if this is true, or if they will be concious throughout the fall until impact. Is there any science on either side of this question?
posted by neodem to science & nature (23 comments total)

No, they do not fall unconscious. If they exit a pressurized environment from above 12k feet they may fall unconscious due to lack of atmospheric pressure, but not the fall. See HALO.
posted by 517 at 10:59 AM on August 17, 2005

"When parachutes were first being developed, people wondered whether someone would survive a long fall, or even be able to remain conscious long enough to activate the parachute. That is why the first parachutes opened automatically. However it soon became clear that a skydiver could fall a great distance and still remain conscious." - from the Free Fall Research FAQ.

A quick glance suggests that none of the stories on that site appear to mention unconsciousness.
posted by Leon at 11:16 AM on August 17, 2005

All skydivers jump out without their parachute enabled. I've never heard of a "consciousness limit" before you have to open it.

Also, there's extremes, like Kittinger

"In freefall for four and a half minutes, Kittinger fell at speeds up to 714 mph, exceeding the speed of sound. He experienced temperatures as low as -94 degrees Fahrenheit. Kittinger opened his parachute at 18,000 feet and landed safely in the New Mexico desert after a 13 minute 45 second descent."
posted by vacapinta at 11:19 AM on August 17, 2005

Right.. there's nothing in the fall itself that would induce unconsciousness. Remember that astronauts in orbit are essentially in one continuous "fall" - and as long as they have oxygen at a certain pressure, they have no problem...
posted by mark7570 at 11:19 AM on August 17, 2005

Off a building, no. From an airplane, possibly. From the rest of 517's link:

At high altitudes of the Earth's atmosphere, the oxygen quantities required for human respiration become thin. A typical HALO exercise will require the use of an oxygen mask, as the parachuter jumps from an altitude upwards of 12,000 feet. This type of technique is dangerous to human health, as the lack of oxygen can lead to suffering hypoxia. Hypoxia may cause loss of consciousness, which in consequence puts the parachuter in a mortal risk situation, as he can suffer death from landing impact by not being capable of opening his own parachute. Another risk is from the coldness at high altitudes. The jumper faces subzero temperatures and risks frost bite.

The height isn't what will make you pass out. If he didn't have the proper equipment, it would be the lack of oxygen and the exceptionally low temperatures.
posted by NotMyselfRightNow at 11:24 AM on August 17, 2005

Wow, vacapinta, thanks for the pointer to Kittinger. What an interesting story- worthy of a post on the blue. You should put one together!
posted by bobot at 11:38 AM on August 17, 2005

Why not ask someone who's parachute failed but they survivied?
posted by gus at 11:45 AM on August 17, 2005

The Kittinger story is incredible. It doesn't state what kind of protective gear he was wearing. Very curious.
posted by anathema at 12:14 PM on August 17, 2005

Kittinger must have been insane. My god, what a story. And the bugger lived through it!
posted by five fresh fish at 1:32 PM on August 17, 2005

I vaguely remember an interview with Richard Branson, as he was about to start his first attempt to cross the Atlantic in a high altitude balloon. He mentioned that he'd had to have all of his fillings replaced, because if he had to evacuate the balloon's capsule at such a high altitude, conventional fillings would explode because of the pressure differential. If that was true, and I've no reason to believe that he would make it up, a mouthful of expoding teeth might induce unconsciousness.
posted by veedubya at 1:36 PM on August 17, 2005

You may be unable to breathe out easily depending on the position you're in while falling, and that might cause you to pass out.

Of course that would take a while to actually happen -- at that point being unconscious wouldn't be nearly as important as the fact that you'll soon hit the ground at very high speed.
posted by clevershark at 1:59 PM on August 17, 2005

I fell off a 3 story building and lost consciousness right after I failed to grab a possible hand hold. I think the surprise and shock put my brain to blue screen. (I survived unhurt)
posted by JohnR at 2:16 PM on August 17, 2005

I think its much more likely, JohnR, that you lost consciousness when you hit the ground and the resulting trauma prevented your brain from forming any long-term memories of the fall.
This is a kind of traumatic amnesia and the phenomenon may have given rise to the notion that people lose consciousness during a fall when, in fact, they lose consciousness at the moment of impact and simply have no memory of the fall.
After the fact, it would be pretty much impossible for someone to distinguish the difference.
posted by Zetetics at 2:48 PM on August 17, 2005

You could be correct Zetetics. I will add that my first reaction to my concerned friends was to report very emphatically that life is a dream, its a dream. If I lost consciousness when I hit, it was very brief because I remember most of the impact.
posted by JohnR at 3:31 PM on August 17, 2005

I don't think a fall makes you pass out. I suspect strongly it's an urban legend kind of thing that is easy to perpetuate, as the number of folks that survive long falls without a parachute is vanishingly small. Plus, it is easy to say having an "out" changes the psychology. But I think it is all urban legend.

As a rock climber, I don't often suffer long falls, but I fall often, and there has never even been the slightest hint that I would be anything but completely awake right up until I smashed into the ground. I've takled to climbers that have taken long falls and remained entirely awake, too.
posted by teece at 3:47 PM on August 17, 2005

In the mid '60's an Air Force transport plane blew out a huge panel from its side at 34,000 ft. The pilot managed to bring it down and land it safely, without oxygen or wearing anything more than a thin flight suit. I was serving as a scientist in an Air Force lab and none of us believed that such a feat was humanly possible.

To investigate this, my commanding officer had a small flight simulator moved into a high altitude chamber, which was then evacuated to the equivalent of 34,000 ft. The chamber was then explosively decompressed and we watched through the windows as he 'flew' the simulator down and landed it. By the time he reached 18,000 ft he appeared very drunk, but still conscious and in control. By 12,000 ft, he was starting to recover some of his motor skills and some reasoning faculties. He hovered around 5,000 ft for a while until he regained some composure and was able to 'land' the simulator correctly.

At debriefing, he said that he had to concentrate on blowing out during the decompression (so as not to explode his lungs) and that his vision went to a narrow tunnel as he fought to remain conscious. The adiabatic expansion made the remaining atmosphere in the chamber very cold, which added to his woes. (It was not as cold as the -35 deg F normally found at 34,000', but it was cold enough to make him shiver.)

His time to reach 5,000 ft was of the order of 4 minutes, as I recall, almost as long as Kittinger's and certainly much longer than would happen from 35,000 ft. The conclusion was that the hypoxia of such a descent would not necessarily totally incapacitate a person. However, in a true free fall the 100 mph + windspeed would freeze the faller very rapidly, to the point where that might cause loss of consciousness. To counter this, it is worth remembering that a Canadian Hercules pilot who crash landed in an arctic blizzard spent more than 20 minutes tending to the wounded, in the open, wearing only a flight suit before succumbing to hypoxia.

One final note: My CO, who flew the simulator, was quite an alcoholic. I have long thought that his familiarity with performing somewhat complex mental tasks while impaired might have helped him significantly while performing this amazing feat. On the other hand, the pilot who landed the original aircraft was completely sober - and highly motivated.
posted by RMALCOLM at 4:15 PM on August 17, 2005

Kittinger fell at speeds up to 714 mph

What the hell is terminal velocity for an average man? It's really possible to fall at that speed or was he propelled somehow?
posted by spicynuts at 5:10 PM on August 17, 2005

Ok, I found a website that says that terminal velocity for a human is about 120 mph. Even if you decrease your surface area by deliberately dropping like a pin, I'm thinking you can't increase your terminal velocity 6 fold. Am I wrong?

Sorry to derail.
posted by spicynuts at 5:13 PM on August 17, 2005

JohnR, its even possible that you didn’t lose consciousness at all.
Consciousness, short term memory and long term memory are somewhat separate processes but we normally can’t perceive the separations. There is a period of time for which we have only ephemeral short-term memories that are being transferred into more permanent long-term memories. If that transfer process is interrupted, say, by trauma resulting from a fall, then we will later have no memory for that time period.
Now, if only your long-term memory processes are interrupted, you will lose memory for some period of time before the impact. However, the short-term memories formed during the impact itself may be transferred without loss, after the momentary interruption.
In every day conditions, periods of time for which we have no memory are roughly equivalent to periods of unconsciousness. So, it would be perfectly natural to interpret the experience as a loss of consciousness during the fall – even if there was no interruption of consciousness at all but only a brief failure of memory.
I’m in the “conscious throughout the fall until impact” camp.
posted by Zetetics at 5:38 PM on August 17, 2005

Spicey, that figure will depend on the amount of air friction, neh? At the 120000 foot mark, there isn't going to be a lot to slow ya down...
posted by five fresh fish at 6:26 PM on August 17, 2005

Never forget the intelligent gravity effect.
posted by peacay at 4:51 AM on August 18, 2005

Thank you everyone for your answers.. To sum up, it appears that if I were flying along in a commercial airplane and it somehow broke up in the air, I would most likely be concious during my fall and impact unless the ailtitude was too high, in which case I may freeze to death...
posted by neodem at 7:31 AM on August 18, 2005

Unless you treat that fear of flying with a good hefty dose of Xanax; which I recommend.
posted by ikkyu2 at 2:59 PM on August 21, 2005