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Comment by owenversteeg | Hacker News Reader

I've written a longer, more detailed comment in this thread, but long things are hard to remember so I decided to condense my advice into a paragraph:

Falling from a plane, you have a minute to land after waking up. You can move laterally 2 miles by controlling your body. That gives you 13 sq miles to land. In this order, aim for: snow, swamp, glass skylights, large bushy trees (but not redwoods.) Water is almost guaranteed death. Stay "flat" until right before impact, and move to a standing position. Relax and go completely limp. If you follow this advice your odds are good.

My more detailed comment, with sources/numbers, is here: https://news.ycombinator.com/item?id=13840660

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Glass skylights, really? Not disputing it, but what's your reasoning? Slowing you down while still breaking before you do?

Also, regarding water: while I've heard the standard comment that hitting water can be as bad as hitting concrete, that seems like it would apply more if you have a larger surface area. Divers can dive from 35+ meters, and hit at 60+ mph, without any injury at all. If you are capable of aiming and landing feet-first and remaining as streamlined as possible, would water still be a fatal option?

If you hit land and survive, you passing out will (probably) not leave you any worse off. If you hit water and survive, you need to remain conscious and be able to move enough to swim somewhere/to something.

Yeah, glass is actually one of your better bets. Two of the 5-15 survivors of free fall incidents fell through glass roofs. You can read more here: https://en.wikipedia.org/wiki/Alan_Magee

The problem is that you're hitting water at 120mph. A 60mph impact of a 50kg person is 35kJ; a 120mph impact of a 50kg person is 150kJ. That's 4.5 times the energy. I'd almost certainly choose water (with a streamlined, pencil dive profile) over concrete, but that doesn't mean it's not going to be far more fatal than any other options.

Nitpick: doubling the speed should merely quadruple the energy, 4.5x is too much.

...and if you have to hit water, close you mouth, hold your nostrils closed, and clench your buttcheeks together. Basically, you need to close all holes into your body that are aligned in such a manner with the water - it will force its way in greatly. The last tip - do that because you don't want a ruptured bowl/intestine...

The water/concrete thing is just a simile, not a statement of fact. It's not meant to be "hitting water at X speed is like hitting concrete at X speed" - otherwise we'd have a lot of dead high divers on our hands. It's just meant to mean "hitting water at high speed isn't very forgiving".

https://youtu.be/yGJqqDaKscQb - 'Mythbusters for the Impatient' video showing dropping a pig onto concrete vs water. The concrete drop actually decapitates the pig!

"Water is almost guaranteed death"

But let's say you are still strapped to your airplane seat, or you can grab hold of another large object and ride it. Are your chances of surviving better landing in water or on ground?

Hmm, in that case, wouldn't it be reasonable to try to somehow throw this extra object under you so that it breaks the surface tension before your fall?

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