Once you break the surface of water, you shall start decelerating at an extremely high rate; in fact, the force exerted on your body because of such an abrupt and rapid change of velocity would be too high to handle
Jumping out of an airplane without a parachute… you don’t need a PhD to know it’s a bad idea. One fairly obvious reason is due to the deadly consequences of such a stunt. However, what if, by some chance, you have to jump out of a moving aircraft? What are the odds of surviving a free-fall from thousands of feet above the ground?
First off, let’s hope that such a scenario never arises.
With a parachute on, you can still hope to land safely, but jumping out of an aircraft without a parachute is obviously a last resort, so it should only be considered when there’s no other viable option of escape from an airplane that is “going down”.
However, if you have to jump, it’s often recommended to look for a large body of water, like a sea or a river, and then try to aim your fall towards that. Even if you do all of that perfectly, what are your chances of survival?
What is wreckage riding?
Before actually jumping out, you should try to find a large object that you can ‘ride’ during your imminent free fall. In other words, be a ‘wreckage rider’ (a term coined by Jim Hamilton, a historian who compiled an online database of every imaginable human plummet). Your chances of surviving such a deadly plunge might improve slightly when you’re somehow padded by semi-protective debris that will absorb some of the enormous amount of energy you’ll experience when you land on the water’s surface.
A lady named Vesna Vulovic (an air hostess from Yugoslavia) actually survived a 10,160-meter (a little more than 10 kilometers) fall when a DC-9 blew up in mid-air. In fact, she’s listed in the Guinness Book of World Records for her miraculous survival. She was crammed between a catering trolley, the body of another crew member and the tail section of the aircraft, all of which absorbed some of the impact energy that she would have experienced all by herself had she fallen without these things surrounding her. Interestingly enough, the first thing she asked for after she awoke from her coma was a cigarette!
Free falling from a moving aircraft that’s cruising at a standard height will eventually cause an individual to reach their terminal velocity, i.e. the velocity at which there is no increase in the velocity of the downward motion of a free-falling body. A normal skydiver, who jumps from a height much lower than where commercial airplanes usually fly in a ‘belly-to-Earth’ position, has a terminal velocity of around 120-140 mph (54 to 58 m/s). Therefore, it’s fair to assume that that could be the minimum value of the speed you would have (depending on your mass) during the free fall.
Hitting the surface of water at such speeds is not much different than jumping from a building and hitting the sidewalk. Although water is not as rigid as the sidewalk, it does have surface tension, which is why water has a tendency to stay together. This also means that it exerts a force on any body that lies on its surface.
Body’s position before the impact makes a difference
Since we’re talking about a human (with considerable mass) falling from thousands of feet in the air, the reactive force that water would offer upon contact would be enormous. This force, however, is influenced by two factors; mass and the cross-section of the object falling into the water. You can’t possibly change your mass during a free fall (or at any other point, really), but you can change the cross-section area of your body.
What this means is that you can assume a position that offers the minimum surface area of your body to bear the brunt of the huge force. You can do this by assuming a feet-first position to ensure a knife-like entry into the water or a head-down position, just like divers do.
Note that assuming these positions necessarily bumps your impact velocity up a bit, as your body becomes more streamlined against air drag.
Once you break the surface of the water, you will start decelerating at an extremely high rate; in fact, the force exerted on your body due to such an abrupt and rapid change of velocity would be too much to handle. Human beings can sustain 100 G’s for short bursts of time (a race car driver named Kenny Bräck survived a racing accident in 2003 wherein a deceleration of 214 G’s was measured), but in the case of falling from a plane, it would be fairly higher than that (around 300 G’s). No human could survive that… not a regular Homo sapien, at least.
Such a huge force would cause an immense amount of internal hemorrhaging and would also throw vital organs into complete disarray, causing fatal injuries to the individual.
All in all, it’s fair to say that your chances of survival are extremely slim if you jump out of an airplane into a body of water without a parachute. However, if one is left with no other choice, keeping these few techniques in mind and remaining composed (as much as a human who is free falling without a parachute could possibly be) may help a little.