Georgios Alexandris/ShutterstockWhether you always request a window seat or you just snagged one on your last flight because you know the window seat increases your chance of catching some shuteye, chances are the tiny little hole in the window has caught your eye. While the concept of a hole anywhere on a plane may seem disconcerting when you consider we’re flying in what’s basically a pressurized tube at 35,000 feet and the air outside is unbreathable, no need to panic. That hole is actually keeping us safe.
As a plane takes off and rises in altitude, air pressure drops. The inside of the plane is pressurized, and that’s what allows passengers to keep breathing easily. That’s not to say our bodies don’t sense a change—for example, the reason why they keep airplanes so cold is to keep some sensitive passengers from fainting. The difference in pressure between the air inside the cabin and outside the plane puts a huge amount of strain on the airplane itself. So this tiny bleed hole—as they call it—allows for some of the pressure to balance out between the window’s triple panes and ensure cabin pressure is applied only to the outside pane.
Another perk of the bleed hole? It keeps the plane’s windows from fogging up. The temperature difference between the inside of the cabin and outside the plane are so vastly different, without the bleed hole releasing moisture from the air gap, all those picturesque views of the earth below us would be masked by condensation.
Now you can add that tiny hole in the window to the mental list of hidden airplane features you never knew about. If you can’t get enough airplane trivia, here are 11 more airplane facts you’ve always been curious about.