The many mysteries of modern aviation: like what happens when you flush a plane loo and why cabin lights are dimmed during takeoff and landing.
But have you ever pondered: why exactly are there tiny holes in plane windows?
Surely we should not have holes in the windows of planes? On the contrary those holes, which are only present in the middle pane of our triple-glazed planes, are actually there to keep us safe. Without them, passengers could be in trouble.
But before we explain how these "bleed holes" help keep us alive, it is important to understand how air pressure changes when you are climbing to 33 000 feet.
As anyone who has scaled a mountain will know, at high altitude the air is less pressurised and contains less oxygen; this is why climbers suffer from altitude sickness. And that is just a mountain; at cruising altitude the pressure outside is even lower.
Inside the plane it is a different story: to make sure those onboard do not pass out, the cabin air is pressurised, which places an enormous strain on the windows.
The inside pane – the one you may have woken up against from time to time – is largely superficial, meaning the middle pane and outer pane are taking the brunt of the pressure.
"The middle pane is the one with the small hole in it," Justin Dubon, of Airbus, said. "The purpose of that hole is to allow pressure to equalise between the passenger cabin and the air gap between the panes."
That little hole also stops the windows from fogging up, meaning you can watch the scenery below unfold as you travel to your destination.
So now you know. Go forth, and impress fellow passengers with your trivia. –
© The Telegraph
