Most of us probably don’t think much about airplane windows—aside from those moments when we’re whipping out our phone for that sweeping aerial shot.
But a string of recent inflight incidents involving broken windows have caused alarm among many travelers, to the point where at least one consumer survey shows that a few fliers are even avoiding window seat assignments. In the latest event, which occurred in China on Monday, one of the panes in the cockpit of a Sichuan Airlines Airbus 319 inexplicably shattered on a flight from Chongqing in southwest China, to Lhasa in Tibet. That caused the compartment to lose pressure, which in turn briefly sucked the first officer partially out of the plane. He was able to regain control and suffered only minor injuries, and the flight crew made an emergency landing.
Chinese aviation authorities are investigating the incident, with the help of experts from Airbus Industrie, and no cause has been identified yet. It was reportedly the sixth window-related scare aboard a plane in a month, beginning with the engine explosion on Southwest Airlines Flight 1380 on April 17; in that case, shards of the engine flew into the fuselage and punctured a passenger window, killing a woman sitting in the adjacent seat, after she too was partially sucked out of the plane.
Between these two terrifying events there was another window scare, again involving a Southwest plane, which was forced to make an emergency landing in Cleveland on a Chicago-bound flight when a passenger window cracked. No one was hurt and the passengers were taken to another plane to continue their trip.
So are these events linked—suggesting a deeper problem with this aircraft component? Safety experts say, emphatically, no.
Damage to windows, even cockpit windows, “is normally not going to make a plane crash,” says John Goglia, a safety consultant and former member of the National Transportation Safety Board. “Back in the early days of jet travel, there were some pretty bad episodes with windows but even then airplanes did not crash.”
Goglia says that cockpit windows in particular are very strong, designed to survive everything from bird strikes—as in Sully Sullenberger’s “Miracle on the Hudson” flight—to hailstorms. “The glass in the cockpit is like a sandwich. It is multiple layers—it’s not like an Oreo cookie with just three layers, it’s got many more.” Passenger windows are also sturdy with several layers for added protection and they are routinely polished to remove what’s called “crazing,” fine web-like lines caused by exposure to the elements and to chemicals, such as those used to de-ice planes.
Responding to a request for comment, the FAA said based on its own data, “passenger window failures are rare.” Statistics show there have been only 26 failures of the outer pane—each exit window has three—in the entire Boeing 737 service history worldwide, another source said.
And despite the recent rash of incidents, it’s important to keep in mind that window damage is extremely rare, Goglia says. For example, the last case of a pilot being sucked out of a cockpit window was back in 1990, aboard a British Airways flight. “He was up to his waist outside the plane,” but managed to recover. The subsequent investigation showed that the accident was caused by improper maintenance. “They used the wrong screws,” when installing the window, Goglia says.
So, what’s behind the other recent cases? Goglia says there are three possible explanations for the Sichuan Airlines episode: improper assembly during routine maintenance; a manufacturing defect at the time the plane was made; or damage from an unknown source that caused a “stress point.”
“Don’t forget in the nearly 30 years since the BA accident, there have probably been 500,000 cockpit windows made (and many more of the passenger variety),” he says. “That’s pretty impressive when you consider how rare this is. “