If you’re a window-seat person, you’ve probably familiarised yourself with the little hole outside your plane window.
Considering windows aren’t usually supposed to have holes, you’ve no doubt had a moment of panic when you first saw one.
But, as it turns out, the holes are there on purpose. And no, they won’t crack and break – they’re actually there to serve an important safety function.
If you look closely at a typical passenger cabin window, you’ll see three panes. The one you can touch from your seat is the first pane, then there’s the middle pane – which sports the tiny hole, called the breather – and finally the outer pane.
Now, as we all know, planes fly pretty high – typically between 36,000 and 40,000 feet, and at that height, the level of oxygen is very low.
Normally down here on the ground, the average human experiences around 15 pounds of pressure per square inch, Indy100 reports, but the higher above sea level we climb, the less pressure we feel. To be exact, at cruising altitudes of around 35,000 feet, atmospheric pressure (the pressure outside the aircraft) is about 3.4 pounds per square inch.
That’s way too low to even be conscious, so to minimise that discomfort, the plane pumps air conditioner into the cabin that’s similar to the pressure we would feel on the ground. But it also causes an imbalance in pressure between outside the plane and inside the plane – and that’s where the tiny hole comes in.
The outer two cabin windows are designed to contain this difference in pressure between the cabin and the sky. And the outer pane usually bears this pressure, thanks to the breather hole.
So, no, the tiny holes are not there to crack and break and doom the entire plane – they’re actually there to help you.
The more you know.