Have you ever sat on a plane, gazing out the window (because you were lucky enough to get the window seat), dreaming about your destination, watching the clouds go by and thought ‘wow, I wonder why all plane windows are round?’? Well you are not alone, but we’re sad to report the reason isn’t fun.

Aerospace engineering has certainly come a long way since the first passenger plane took flight in 1914. Back then they didn’t really have windows, but over time that changed and in the 1940s  the world’s first commercial jetliner, the de Havilland Comet, was transporting people through the skies… with square windows.

It carried 30,00 passengers at 30,000 feet in its first year (including Queen Elizabeth, the Queen Mother and Princess Margaret!) but it wasn’t all smooth flying. It was lauded as an amazing innovation, and it was, but later there were two fatal crashes, where the planes literally fell apart midair.

FELL APART MIDAIR.

Wrap your head around the sheer terror of that for a second. Naturally, this resulted in an enquiry into the planes and the findings declared the crashes were caused by structural weaknesses in the fuselage. These weaknesses were caused by the cabin pressure bearing down on the metal corners of the square windows. In fact, the right angles were receiving two or three times the pressure of elsewhere in the cabin, leading to cracks or the whole windows blowing out. 

Enter the round window. A round window has no corners so the pressure is evened out. They’re also a stronger shape so are less likely to warp over time and cause faults. The Comet and other airlines introduced them to their planes as well us upping the thickness of the windows to the depth we have today on planes like Boeing. 

So there you have it! Round windows aren’t simply a design choice, but rather a much needed safety choice.