Aviation experts explain why plane windows crack during flight after sudden surge in incidents

There have been three separate incidents reported in recent weeks of flights being turned around to their departure airport after suffering from shattered or cracked windows, with public concerns raised that this might not be coincidence.

This comes after a SunExpress flight heading to Vienna, Austria, was forced to head back to İzmir, Turkey, after it reported a crack in a cockpit windshield on September 6.

Just a few weeks later, on September 27, a United Express plane bound for El Paso, Texas, made an emergency landing back in Houston after the cockpit windshield shattered during takeoff.

In a third incident on October 13, a crack in a passenger window of a British Airways plane caused the flight to turn around mid-journey as it traveled over France heading for Faro, Portugal. Instead, the plane returned to Gatwick Airport in London.

Are window cracks on planes an increasing problem?

While three incidents in a matter of weeks can spark concern, it isn’t a trend yet, according to experts.

There have been three separate incidents reported in recent weeks (gece33/Getty Images)

Justin Crabbe, an FAA commercial pilot and CEO and founder of private aviation marketplace Jettly, explains: “I understand that these incidents happening in a short period of time would naturally raise questions, but there is no evidence yet to establish that window failures are becoming more frequent.

“Windows are multi-pane by design. The outer pane carries cabin pressure, and a crack in one layer doesn't mean failure. But of course, safety should take precedence over schedule. When a potentially significant defect is identified, returning to the airport or diverting is the most logical and immediate solution. Turning back, however, doesn't mean an aircraft has compromised structural integrity; it's a precautionary measure for an issue that requires further assessment.”

However, there could be an explanation for why windows are cracking, as Monica Badra, founder and CEO at Aero NextGen, an aviation-specific solution hub and matching platform, points out: “Whether this represents a wider trend is harder to say with certainty. Three incidents in roughly six weeks across different carriers could be coincidental. What it may reflect is the broader industry reality of aging fleets operating longer than originally planned, partly due to delayed new aircraft deliveries.”

There are multiple common causes for why a plane window might crack (Donald Iain Smith/Getty Images)

Common causes of plane window cracks

There are a number of reasons why cracks might appear in a window of an aircraft, with Crabbe listing common causes as things like debris impact, fatigue from many pressurization cycles, technical issues, or thermal stress.

The severity of the problem depends on which pane or component of the window is damaged, the extent and location of the damage, and any applicable maintenance and operating requirements.

Badra adds: “There is also a small breather hole in the middle pane that equalizes pressure between layers and prevents moisture buildup. This layered design means a cracked outer pane, while serious enough to warrant a diversion, does not create immediate catastrophic risk. The system worked as intended in all three of the recent incidents.”