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While googling about Ben Goldacre, I came across the following reductio ad absurdum argument:

Nerd, can you point me to the data that shows that wearing a parachute increases your life expectancy when jumping out of a plane? You see, someone claimed that it is helpful, but there s nothing in the data to support this. I cannot find any reference to a double blind trial, I can’t find any peer-reviewed studies, and I cannot even find a pilot study comparing survivability with or without a ‘chute. Is it bad science to rely on anecdotal data here? If not, why not?

I guess there's the hypothetical about "What would you do if there weren't any peer-reviewed papers about parachutes?", but I'm interested in whether there's any scientific papers supporting the use of parachutes.


The papers don't necessarily have to involve double-blinded randomized experiments on humans. For example, the paper High-rise syndrome in cats concluded that the survival rate of cats increased as the height increased, possibly because cats become more relaxed once they reach terminal velocity, and possibly because it has more time to prepare for the landing. Rather than a double-blinded study, they observed 132 cats who had been "diagnosed" with high-rise syndrome over a 5-month period.

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    having seen people who've survived parachute failures as well as people whose parachutes did not fail, I'd rather jump with one (and have it work of course) than without one, even if my chances of survival didn't increase by using one. Empirical evidence, probably not a statistically large enough sample size to pass peer review, but it's good enough for me :) – jwenting Mar 21 '11 at 6:48
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    Double blind controls are used in drug testing because the outcome of the trial can be influenced by either the patient's or the doctor's expectations (Placebo effect, confirmation bias). This can, for quite obvious reasons, not happen with a parachute. Therefore, no need for a blind study. – Lagerbaer Apr 29 '11 at 21:56
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    @Lagerbaer: Isn't "for quite obvious reasons" hand-waving? – Andrew Grimm Apr 30 '11 at 0:25
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    Maybe. But certainly not in the case of broken bones or crushed internal organs. :) – Lagerbaer Apr 30 '11 at 3:52
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    Make sure you include a placebo group. – fredley Jun 8 '11 at 8:57
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The author of that comment is probably referencing Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials which is pointing out the absurdity of radical evidence based medicine. From the abstract:

Conclusions As with many interventions intended to prevent ill health, the effectiveness of parachutes has not been subjected to rigorous evaluation by using randomised controlled trials. Advocates of evidence based medicine have criticised the adoption of interventions evaluated by using only observational data. We think that everyone might benefit if the most radical protagonists of evidence based medicine organised and participated in a double blind, randomised, placebo controlled, crossover trial of the parachute.

A discussion follows and I'm content with this comment that addresses the absurdity of demanding an explicit medical answer:

Not the common sense but simple laws of physics can prove the effectiveness of the parachute as a life saving intervention. When a person jumps from a height accelerates towards the earth and eventually reaches the “terminal velocity”. For an average person this terminal velocity is about 200km/hour and it takes only about 3 seconds to reach the terminal velocity. The damages caused to an individual hitting the ground at this speed is not just broken arms! Now, introducing a parachute reduces this terminal velocity to less than 10km/hour. This is comparable to crashing an old car without any airbags to a solid concrete wall at 200km/h and 10km/h.

According to Wikipedia (and other sources) the Guiness world record for falling without a parachute belongs to Vesna Vulović who fell 10,000m, with several more people falling over 5,000m during WWII. The Wikipedia article also references a pub med article Ten years of experience with falls from a height in children. that states

Falls from a height are a major cause of accidental death in urban children. The medical and social data on 61 children admitted over the last decade for falls of one or more stories were reviewed. Seventy-seven percent of the children survived. Of the children who fell three stories or less, all survived (100%). Fifty percent mortality occurred between the fifth and sixth floors. Seventy-seven percent of the falls were accidental and 23% of the children jumped or were pushed. The 96% decrease in accidental falls from windows since 1979 demonstrates that the "Children Can't Fly" program in New York City has almost eliminated accidental falls from windows in our hospital population.

There are countless of articles about the injury rate of parachuting and base jumping that all give about the same numbers. Parachuting injuries: a study of 110,000 sports jumps from 1987 states:

A total of 110,000 parachute jumps resulted in six (0.005%) fatalities and 155 (0.14%) cases, requiring medical treatment. The latter group sustained 176 injuries of which 36.9% were significant soft tissue lesions and 63.1% fractures. Landing is the most dangerous part of the parachuting procedure, causing 83.8% of the accidents, while 9.3% were caused by faults during opening of the parachute.

On the age of those that participated it states:

The mean age was 29.3 years, range 16-62 years.

Working with the assumption that survivability doesn't increase with falling distance, and that age doesn't profoundly diminish the damage cause to humans by rapid deceleration, we must conclude that it's the parachutes responsible for the increase in survivability from 50% when falling from the fifth to sixth floor to 99.995% when jumping out of an airplane.

TL;DR

Is the use of parachutes supported by peer-reviewed papers?

Yes, there are many papers that that show that parachutes are being used.

Does the literature show that parachuting increases survivability over free-falling?

Yes, indirectly.

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    I've always thought "longest fall without a parachute" was an unfair award - as you say, you reach terminal velocity quite quickly. After that it surely don't really matter how long you fall for! – Phoshi Mar 21 '11 at 8:46
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    Unless you fall in a vacuum, but I suppose you'd be more worried about the depressing lack of air and effects of approaching the speed of light. – Kit Sunde Mar 21 '11 at 8:53
  • Ouch, now that'd be a hell of a way to go! – Phoshi Mar 21 '11 at 9:40
  • @kit I deleted my answer, your edit incorporated the one or two points I made about studies of people falling vs studies of people falling with parachutes. Nice answer. – Dogmafrog Mar 21 '11 at 16:20
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    200 kph is 55 m/sec. Given gravity of 10 m/sec/sec, it takes nearly 6 seconds (ignoring wind resistance) to reach that speed: not 3 seconds. – ChrisW May 20 '11 at 2:55
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The question commits the logical fallacy Unstated Major Premise. It presumes that because parachutes have to do with the safety of humans, that they must therefore be studied using a randomized controlled trial before we can ethically use them. This is bogus.

There are some interventions, even medical ones, which are have such a high prior plausibility that it is not necessary, advisable or even ethical to study them. For example, if a person is on fire, logically one must extinguish the fire before tending to their burns. One does not need to launch a randomized controlled trial on this first. In fact, it would be unethical to do this study in the first place, because doing so would put the test subjects at high risk of harm.

And so it is with parachutes. Basic knowledge of human anatomy tells us that falling from a great height produces a very high likelihood of severe injury and death. There are literally millions of empirical cases that back this up, more happen every day. Therefore use of parachutes in situations where falls from great heights are necessary is logical and does not require an RCT first.

Now, that isn't to say you couldn't study particular designs of parachutes to see which ones are more effective. And these of course could be done without using human subjects.

  • You may have a valid point, but I think it belongs in meta or a comment to the question. I downvoted as this did not answer the question directly: "I'm interested in whether there's any scientific papers supporting the use of parachutes." – Jason Plank Mar 21 '11 at 15:42
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    @Jason: Though neither of the other answers which you haven't downvoted does. Tim's answer is pretty much in line with one of the reader comments to above cited prank study in the BMJ. Which, as nobody seems to have noticed, was neither serious nor scientific in any way, but merely an under-the-belt attack at EBM. Though admittedly it was moderately funny (and surprising that BMJ would actually print it). – dm.skt Mar 21 '11 at 17:08
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    @dm.skt: Kit's answer does answer the question directly. The information about why there are no papers supporting parachute use are relevant, but this information alone does not answer the question. – Jason Plank Mar 21 '11 at 17:16
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    Yes, and my answer is designed to point out that you are using a fallacious premise to question that dogma. It's like asking the question, "When did you stop beating your wife?" There is no correct answer. – Tim Farley Mar 25 '11 at 17:19
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    +1 this is one of those good answers where logic is sufficient to make a good answer. – matt_black Oct 29 '12 at 0:17

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