Why the hole in the window

I love getting the window seat when I fly.
Totally. It’s one of the few things that is good about flying (note to self, remember to find out what it takes to get ‘TSA pre-approve’ status).
Listening to Trance while looking out the window at 30,000 is just bliss.

If you have spent even more than a quick flight sitting at a window seat, I bet you have noticed the hole in the window…. Why is it there?


I’m glad you asked. Here is the answer…..

The middle pane (with the breather hole in it) and the outer pane are more important. 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.

The hole is there to even out the pressure between the scuffed up, previous passenger smeared inner window, the middle window and the outer window.
It also stops the inner to middle window from fogging up since the inside of the plane is a lot (lot) warmer than the outside.

So there you have it.
The hole regulates pressure and temperature.