You’ve never even thought about the reason why, have you? Neither did we.
Although, if you really think about it why would they make rounded windows and not normal squared ones – you would think it would’ve been a given seeing as squared windows work for our cars and homes for generations.
However, when the commercial jetliner rose to prominence in the 1950s, capable of flying at greater speeds and higher altitudes than ever before, two planes fell apart—literally disintegrated—in midair.
The cause? Square windows. Sharp corners are natural weak spots where stress concentrates, weakened further by air pressure. When subjected to repeated pressurization, four corners on a square window spell disaster.
Curved windowpanes on the other hand, which have no focal point, distribute that stress, reducing the likelihood of cracks or breaks. Circular shapes are also stronger and resist deformation, and can thus survive the extreme differences in pressure between the inside and outside of the aircraft.
Keep that in mind the next time you’re gazing out that window seat!