Airplane windows weren't always round because there was a time when most planes had square ones. But have you ever wondered why they changed it? Well, it was more than just having round windows being visually appealing to the eyes of the passengers. In fact, it was literally a life-changing decision and here's why.

According to USA Today, the switch from square windows to round or oval ones happened around the late fifties. Before that, most planes had square windows and it was a more popular choice used among aircraft builders.

But when the first commercial jetliner in the world, the de Havilland Comet, rose to prominence, everything about planes having square windows was all about the change. The square-windowed aircraft took its first flight in 1949 and it did make a big impact on air travel for the whole world since it was capable of flying at higher altitudes and greater speeds.

The Comet's built gave it an edge among its competitors and it was able to accommodate 30,000 passengers all in one year since it first flown the skies. In fact, one flight in 1953 even carried Queen Elizabeth, the Queen Mother and Princess Margaret. That flight was specially arranged by Sir Geoffrey and Lady de Havilland themselves.

The company was doing remarkably great and it did live up to its expectations having flown eight Comets from London every week to different countries in the world during the summer of 1953. But unfortunately, the planes' square windows changed all that because it was the cause of the two crashed in 1954.

Two flights, one coming from Rome and another flying to Johannesburg, crashed and caused 56 deaths. It was found that the sharp corners of the square windows accumulated too much stresses at the corners. According to The Telegraph, these angles were weak spots that gained more pressure compared to other parts of the cabin.

The crash resulted in the modification of the windows to oval -- the circular shape of the windows distribute the stresses evenly. As you can see, the switch was really a life-changing decision because without round windows, there would probably more cases of crashes.