Why Are Airplane Windows Round?

The Engineering Secret That Keeps You Safe at 35,000 Feet

Ever stared out the airplane window mid-flight and wondered:
“Why is it round?”
Wouldn’t a square one give you more view?

It turns out, this tiny design detail is one of the most important safety features in modern aviation, and it was learned the hard way.

The Fatal Flaw in Square Windows

Let’s rewind to the 1950s, when commercial air travel was just taking off, and it was as glamorous as it was experimental.

Enter the de Havilland Comet, the world’s first commercial jet airliner. It was fast, sleek, and luxurious (for its time). And it had square windows.

Sounds fine, right?

Until tragedy struck. In the span of just over a year, three Comet jets mysteriously broke apart mid-air, killing all passengers aboard. Investigators were baffled. Until they looked closer.

Stress + Sharp Corners = Disaster

Engineers discovered a critical design flaw:
Square windows create stress points at the corners.

At high altitudes, airplane cabins are pressurized so passengers can breathe comfortably. That pressure pushes outward against the fuselage, and any weak spot becomes a risk.

Sharp corners concentrate stress.
Every time the cabin was pressurized and depressurized, tiny cracks formed in the corners of the square windows. Over time, they grew, until the entire fuselage tore apart.

Why Round Wins Every Time

The fix? Circular windows.

• No corners = no stress concentration

• Even pressure distribution around the frame

• Far less likely to crack or fail under pressure

It’s simple, brilliant engineering, and it became the new standard overnight.

Today, airplane windows are oval or perfectly round for one reason only:
They keep you alive.

Bonus Fun Fact: Why They're So Small

Ever wonder why airplane windows seem so small?

It’s not to torture you, it’s because larger windows would weaken the fuselage. Every opening in a pressurized aircraft is a structural compromise. Small, round ones? Much safer.