It’s hard to imagine aircraft having ungainly square windows – but they once did. It was not until late into the Fifties that the round or oval cabin windows we all know and love were introduced, and it was not merely for aesthetic reasons.

Kitted out with square windows, the de Havilland Comet was the world’s first commercial jetliner. First flown in 1949, it was set to revolutionise air travel for millions.


At first, the Hertfordshire-made aircraft lived up to the hype, carrying 30,000 passengers in its first year, including Queen Elizabeth, the Queen Mother and Princess Margaret, guests on a special flight in 1953, hosted by Sir Geoffrey and Lady de Havilland. Its engines allowed the Comet to fly higher than its competitors, above 30,000 feet, increasing speed by as much as 50 per cent as well as avoiding bad weather.

By summer 1953, eight Comets were leaving London each week, bound for Johannesburg, Tokyo, Singapore and Colombo. BOAC was a key customer, while Air India, Pan Am and Japan Air Lines were just a few of the raft of carriers to place orders.



But its windows were to be its downfall. Two fatal crashes in 1954 – Flight 781 from Rome and Flight 201, bound for Johannesburg – accounting for 56 lives, were found to be the result of structural weaknesses in the fuselage, caused by dangerous stresses at the corners of the square windows. The harsh angles meant that the surrounding metal experienced pressure two to three times greater than elsewhere in the cabin.

A number of inquiries into the crashes highlighted metal fatigue as a key cause of the fuselage breaking up, prompting de Havilland to modify the design of its later aircraft, introducing the stress-alleviating oval windows that we see today. The company also increased the thickness of the Comet’s fuselage walls.

Over the years, aerospace engineering has made huge leaps in aeroplane technology, meaning planes can carry more passengers and go faster. The planes have also changed shape to increase safety – including the windows.

The reason for the crashes?

The windows.

Where there’s a corner, there’s a weak spot. Windows, having four corners, have four potential weak spots, making them likely to crash under stress – such as air pressure.


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