Ever wonder why there’s a tiny hole at the bottom of airplane windows?
It’s a common feature on passenger planes, and now an expert has revealed that this seemingly insignificant hole plays an important safety role.
If you look closely at a typical passenger cabin window, you’ll see three panes, typically made of acrylic materials. The purpose of the innermost pane—sometimes called the scratch pane is merely to protect the next one.
The middle pane (with the breather hole in it) and the outer pane are more important.
It’s all-too-easy to let your mind wander when you’re confined to a tiny box of space while hurtling 40,000 feet above the ground and going to hundreds of miles per hour, but rest assured: every single window on the airplane has the same hole. That itsy bitsy hole in the bottom of your airplane window is actually a very important safety feature.
The hole is called, a breather hole. It helps to regulate how much pressure from the cabin is exerted onto the airplane windows making sure that if the window is going to break, the outer pane goes first. It’s the outside panel that gives out (meaning you can still breathe).
Generally speaking, as an aircraft climbs, the air pressure drops in both the cabin and the outside air—but it drops much more outside, as the aircraft’s pressurization system keeps the cabin pressure at a comfortable and safe level. This means that the pressure inside the aircraft during flight is typically much greater than the pressure outside.
Not only that, the breather hole also keeps the window fog-free by wicking moisture that gets stuck between the panes. So, that’s it folks, mystery solved!