Accidents on U.S. airlines have become increasingly rare except for one category of in-flight mishap that has remained stubbornly prevalent: turbulence that leads to serious injuries.

More than 65% of severe injuries — or 28 of 43 — logged by U.S. accident investigators from 2017 through 2020 on airliners resulted from planes encountering bumpy skies, triggered by atmospheric conditions that could be worsening due to climate change.

U.S. accident investigators said much more should be done to protect people, particularly flight attendants. The problem has been exacerbated by insufficient weather reporting, antiquated data technology and outdated federal guidance to airlines, the National Transportation Safety Board said.

“Turbulence is the most common airline accident type today and it’s high time we reduce turbulence-related injuries,” NTSB acting Chairman Bruce Landsberg said.

The sweeping NTSB findings ranged from seeking better ways to secure children 2 years old and younger, who don’t need to be belted in, and calling on the Federal Aviation Administration to order flight attendants to be seated and strapped in for longer periods, where they’re almost never injured.

“Almost all passenger injuries happen to the unbelted,” Landsberg said. “So, stay buckled in, except when out of your seat, and especially when the seat belt sign is on.”

Advertising

Because they have to be on their feet far more than passengers, flight attendants are the most vulnerable, according to NTSB data. Flight attendants were 24 times more likely to be seriously injured, the NTSB said.

They’ve been slammed off ceilings, walls and floors, suffering broken vertebrae and other fractured bones as well as head injuries, according to NTSB accident reports.

“This is a major source of occupational injury,” Sara Nelson, president of the Association of Flight Attendants-CWA union, said in an interview. “Addressing the issues with turbulence has been an issue for us for a long time.”

The NTSB report comes as evidence is growing that global warming is increasing the risks of jets encountering air turbulence. A 2019 study in the journal Nature found so-called wind shear — sudden changes in wind speed or direction — had increased 15% over the North Atlantic since 1979.

The U.S. skies have enjoyed an unprecedented period of safety for more than a decade. There have been only two U.S. passenger deaths since 2009, a woman on a Southwest Airlines flight on which an engine blew apart and a man on a small turboprop plane in Alaska who was hit by a broken propeller blade.

The industry has essentially wiped out entire categories of crashes, such as those caused by icing and wind shear.

Advertising

But turbulence, which can buffet a jet even in clear skies and has proved difficult to accurately predict, has been far tougher to contain. Such buffeting can occur near thunderstorms, in roiled air above mountains and at high altitudes where wind speeds can differ suddenly.

A Feb. 13, 2019, Delta Air Lines flight from Orange County, California, to Seattle is typical.

Pilots on the northbound flight, operated by Delta partner Compass Airlines, kept the seat belt sign illuminated because of an earlier report of “occasional light chop,” but allowed flight attendants to begin serving drinks.

Out of nowhere, the Embraer SA ERJ 175 hit a band of severe turbulence that lasted eight seconds. Two flight attendants were flung into the ceiling and back down to the floor, the NTSB said.

One of the two attendants broke her arm, which constitutes a serious injury under NTSB’s definition. Such injuries also include cases with severe bleeding and a hospital stay two days or longer.

A passenger who had been in the lavatory on the flight also suffered a head wound.

Advertising

The FAA, which sets safety rules and whose air traffic controllers guide airline flights, has been working on multiple fronts to reduce the risk, it said in an emailed statement. It’s developing a system to allow pilots to share turbulence reports digitally, for example.

But the FAA’s advice to the industry was last updated in 2007 and much has changed in the intervening 14 years, the NTSB concluded.

The NTSB issued more than two dozen new and reiterated recommendations to government agencies and airline groups.

Investigators said new technology could help prevent encounters with turbulence by providing better warnings to pilots. For example, air traffic controllers now rely on mostly cumbersome written turbulence reports. They should be able to see areas of turbulence on their radar displays, the NTSB said.

Existing radio transmitters on airliners should be updated with existing technology to automatically report turbulence, investigators said.

Since many injuries occur at lower altitudes, particularly during descents to airports, the government and industry should look at requiring attendants to be seated for longer periods during those times, the NTSB said.

Increasing communication about existing weather conditions would help, Nelson said. Airlines should improve how they share information with each other and between pilots and flight attendants, she said.