Why We Can't Open The Windows Inside A Plane

5 years ago

Mitt Romney is shocked, just shocked, that you can't roll the windows down in a commercial aircraft. We'll let the News & Politics section tackle what that means as far as our country's future in terms of science and technology, and enjoy this opportunity purely for its educational value.

According to the Los Angeles Times, Ann Romney’s plane had had to make an emergency landing on its way to California due to an electrical malfunction.

"I appreciate the fact that she is on the ground, safe and sound. And I don't think she knows just how worried some of us were," Romney said at a Beverly Hills fundraiser on Saturday night. "When you have a fire in an aircraft, there's no place to go, exactly, there's no -- and you can't find any oxygen from outside the aircraft to get in the aircraft, because the windows don't open. I don't know why they don't do that. It's a real problem. So it's very dangerous. And she was choking and rubbing her eyes. Fortunately, there was enough oxygen for the pilot and copilot to make a safe landing in Denver. But she's safe and sound."

Photo by Lachlan Hardy. (Flickr)

To see how air travel and the needs of bodies intersect, I hit up Michael Habib, Assistant Professor of Cell and Neurobiology at the University of Southern California, who also happens to be a world expert on the mechanics of animal flight and bio-inspired robotics.

"Opening a window would help put out the fire, potentially," he told me with a laugh. "For the same reason the passengers would pass out."

You know -- lack of oxygen. But to get the full rundown, I asked him to give me a blow-by-blow on how planes work and just why open windows would present a problem:

Commercial aircraft fly far above the ground (usually 30,000 feet or more) so that they can move at high speeds with less fuel. That's higher than even the tallest mountain peaks. At that great altitude, the air is both thin and cold. Exposure to that thin, cold air would both freeze and suffocate a human (though some birds can survive it). So, unless you happen to be a duck, as a passenger on an airplane, you need to be protected from the cold, thin air.

When I say the air is "thin" I mean that it is low density. As you go higher in altitude, there is less air above you pressing down. So the air is less compact -- we say it has lower density. This means less of every part of the air for any given amount of space. That includes oxygen, which is why we find it difficult to breathe at 30,000 feet.

Airplanes have special interiors that are warm and have denser air than outside. We say that the cabin is "pressurized," meaning the air inside needs to be placed at higher pressure to keep it less thin (i.e. denser) than the air outside the plane when it is flying at high altitude. The inside of the airplane can only stay warm with breathable air if it is sealed from the outside. This is why the doors are so thick and lock very tightly. It is also why the windows do not open. If a passenger opened a window at high altitude the warm, thicker air inside the plane would flow outside very quickly, and the inside of the plane would quickly become cold and lose density -- making it hard to breathe inside the plane. It is worth noting, as well, that the air just outside the plane is even thinner (that is, has even lower density) than just being at high altitude does because the plane is moving so quickly.

An open window would create powerful suction immediately around it, though it would not suck everything out as you see in movies. Mostly passengers inside would feel short of breath and start to pass out. Small objects might be pulled out the window. There would be a loud pop and after that, the sound of a power-sustained gust of wind, as air flowed out of the inside of the airplane. Air would keep flowing out of the open window until the pressure inside the plane was the same as the pressure outside -- in most cases, this would mean making up about 22,000 feet worth of pressure in minutes.

Keep in mind as well that this all means the windows on airplanes need to be quite strong; that also makes it a problem to make them able to be opened. There are a lot of balances that have to be struck on airplanes to keep them both safe and flyable. Air travel is much more constrained than land travel. Structural strength is a consistent issue on planes.

A fun side note: safety factor on a typical airplane is about 50 percent; in most flying animals it is 200 to 220 percent. That means planes are built to take 50 percent more force than you expect them to actually ever encounter. But birds do crazy stuff. Falcons manage roughly 24g's of deceleration at the end of stoops. That would kill a human. In a g suit. In a top-of-the-line jet fighter.

Inside a plane, one has oxygen masks in case pressure in the cabin is lost. But that doesn't solve the temperature problem. Most commercial airplanes fly even higher than the peak of Everest. In the middle of summer, the peak of Everest is about -20°C or about -4°F (i.e. 36 degrees below freezing) -- and that's on a balmy day. Passengers would enter hypothermia rather quickly -- particularly as they probably aren't flying in Antarctic adventure gear. That's why if there is a loss of the pressure seal, and the masks deploy properly, the pilot needs to get to lower altitude quickly.

Well, that's one reason, at least. Another reason for lowering altitude is that there isn't an unlimited supply of oxygen on board, meaning the masks will eventually run dry. Another reason is that sudden pressure drop can cause some passengers to pass out before they manage to get a mask secure. On the aerodynamics side, if there is some sort of structural emergency, it may be prudent to slow the plane down and the minimum speed is lower where the air is thicker.

There you have it, Mittens – and anyone else who has wondered why we can't roll down the windows in a 747.

AV Flox is the section editor of Love & Sex and Health on BlogHer. You can connect with her on Twitter @avflox, Google Plus +AV Flox, or e-mail her directly at av.flox AT BlogHer.com

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