CLEVELAND, Ohio (KTVU) - A Southwest Airlines flight made an unscheduled landing in Cleveland on Wednesday after a window broke. The window panes on a Southwest airplanes and other commercial aircraft are made of two pieces of Plexiglass forming an insulated barrier to protect cabin pressure.
“The thicker one on the inside, the thinner on the outside,” said Dr. Fred Barez, chair of San Jose State University’s aviation department. Barez said cracks in side windows are rare, but normal flight stress can weaken the material over time, leading to failure.
“There’s going to be the pressure effects on the airplane during the flight as well as thermal effects. And the fact that the plane is going to take off and land and the whole window is going to go through various effects of pressurization,” said Barez.
Twitter user @ChaikelK tweeted a photo of the damage. He said his friend had taken the photo, but wanted to remain anonymous.
The flight had left Chicago Midway International Airport and was headed to Newark Liberty International Airport when the plane was diverted. The plane landed at Cleveland-Hopkins International Airport for maintenance review of one of the multiple layers of a window pane.
Southwest released a statement that read in part, "The plane (diverted to) Cleveland-Hopkins International Airport for maintenance review of one of the multiple layers of a window pane. The flight landed uneventfully in Cleveland. The aircraft has been taken out of service for maintenance review, and our local Cleveland Employees are working diligently to accommodate the 76 Customers on a new aircraft to Newark."
Southwest says the plane maintained pressure and no emergency landed was requested. The flight landed uneventfully with no reports of injuries.
This is the second equipment incident involving Southwest in a little over two weeks. On April 17, a woman was killed when she was partially sucked out of a window that shattered when struck by an engine fan blade.
Doctor Barez said the doubled-paned Plexiglas windows are far stronger than glass, and designed to be impact resistant.
KTVU reporter Jesse Gary dropped a rock on one of two pieces. The object bounced off and there were no signs of cracks. But the thinner pane, which represents the outer window, snapped in-two under the same condition.
Barez said he doesn't believe passengers are at risk. “As you can tell these planes have been around for many, many years. It’s a freak accident that took place,” he said.
The NTSB will investigate the accident, and may require more frequent checks of the seals around plane windows. But don’t look for thicker pieces of Plexiglas anytime soon. Doctor Barez said thicker plexiglas would mean added weight, and added cost per ticket to the consumer.