QUICK! You’re flying shotgun in a helicopter, and the engine goes out. Also, the pilot you hired for the day is dead, for some reason. Don’t worry about why. Doesn’t matter. You need to land the helicopter, now. Stop praying and watch this video.

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Or maybe, watch the video before you get into this situation, because it’s probably longer than the amount of time you have left in the sky.

Many people don’t know this, but if a helicopter’s engine goes out, it’s not necessarily going to fall out of the sky. That’s because choppers have a trick up their sleeves called “autorotation.” If you’re flying in an airplane and your engines go out, you can just glide that little plane down to earth and, theoretically, make a controlled, smooth landing.

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While many, including apparently Neil deGrasse Tyson (who is featured in the video below), don’t think the same holds true for a helicopter, choppers can make clever use of aerodynamic forces to descend in a controlled manner. Here’s a video from SmarterEveryDay showing how it works:

Essentially, as soon as the engine goes out, the rotor becomes uncoupled with the engine and begins to “free-wheel.” The pilot immediately lowers a control stick called the “collective,” which drops the angle of attack of the rotor.

Because the rotors are just airfoils like airplane wings, dropping the pitch reduces lift and drag and thereby allows the aircraft to maintain its rotor speed— a crucial step for the pilot to maintain control and for the chopper to maintain some level of lift.

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The pilot then descends in a controlled autorotation with a forward velocity, at which point, he or she will slow the aircraft’s forward velocity, producing a flare that increases rotor speed.

With the extra rotor speed, the pilot can pull up on the collective, thereby increasing the rotor’s pitch, to get more lift during the final few feet to cushion the landing.