ADVERTISEMENT

Why Airplane Windows Don't Roll Down

Were you to open a plane window, the compressed air inside would rapidly rush out, atmospheric conditions inside and outside the plane would equalize, and everybody would die



Flickr/psd

In his latest gaffe, Republican presidential candidate Mitt Romney lamented the fact that airplane windows don't roll down.

Romney's wife Ann's plane had to make an emergency landing Friday (Sept. 21) because of an electrical malfunction. Discussing the incident at a fundraiser the next day, he said: "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."

Here's why they don't do that.

Gravity tends to keep air molecules concentrated near the ground, so the atmosphere thins out as you go up. The air becomes so thin at 10,000 feet (3,000 meters) or so that airplane cabins must be pressurized above that altitude to prevent occupants from suffering from hypoxia, or lack of oxygen. Because temperature and pressure go hand-in-hand (i.e. low-pressure air feels cold), pressurization is also necessary to keep cabins sufficiently warm.

At 35,000 ft. (11,000 m), the typical altitude of a commercial jet, the air pressure drops to less than a quarter of its value at sea level, and the outside temperature drops below negative 60 degrees Fahrenheit (negative 51 degrees Celsius), according to The Engineering Toolbox. Exposed to such conditions, you would quickly die.

Pressurization is normally achieved by pumping the cabin with "bleed air," or compressed air sucked in and heated up by the plane's turbine engines. Pressurization only works in an airtight fuselage. Were you to open a plane window, the compressed air inside would rapidly rush out, atmospheric conditions inside and outside the plane would equalize, and everybody would die.

Plane windows that roll down would therefore be, in Romney's words, "a real problem."

Copyright 2012 Lifes Little Mysteries, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Share this Article:

Comments

You must sign in or register as a ScientificAmerican.com member to submit a comment.
Scientific American Dinosaurs

Get Total Access to our Digital Anthology

1,200 Articles

Order Now - Just $39! >

X

Email this Article

X