Why Some Flight Routes Are More Turbulent Than Others

In-flight turbulence is nothing new, but those who believe it’s on the rise got fresh evidence recently, with two cases of severe turbulence occurring in short succession.

First, there was the terrifying episode on May 21 aboard Singapore Airlines flight 321 from London to Singapore, in which one passenger died (of a reported heart attack) and dozens more were injured. That was followed by Qatar Airways flight 107 from Doha to Dublin this past weekend, which ran into turbulence serious enough to send 12 people on board to the hospital to be treated for injuries. Investigations into the causes of both incidents are underway.

All this has resulted in growing concerns that as extreme weather events grow more common due to climate change, so do the odds of more mile-high scares.

But some promising developments could improve safety while up in the air: A bill reauthorizing the Federal Aviation Administration (FAA), which recently passed Congress and was signed into law, includes a little-noticed provision that directs the agency to adopt a series of safety recommendations that could lower the rate of injuries. Those proposals, which emerged from a 2021 report from the National Transportation Safety Board (NTSB), range from better coordinating weather data to encouraging the use of child safety seats.

The NTSB report noted that “turbulence-related accidents are the most common type of accident” involving U.S. airlines in recent years, most of which result in one or more serious injuries.

Improved technology and better monitoring of conditions could help pilots navigate around the most extreme weather conditions, the NTSB stated.

“We’ve gotten better at predicting these incidents,” said John Cox, a longtime pilot and president of Safety Operating Systems, an aviation safety consultancy.

He emphasized that while better technology to warn pilots may help, some of the best precautions are of the low-tech variety: Aviation experts have long argued that fliers should stay belted at all times when seated, even when the seat-belt sign is turned off.

Aside from this common-sense advice, is there anything else fliers can do to protect against—or even avoid—a bumpy ride?

Are some flight routes more at risk of turbulence than others?

Turbulence can happen anywhere, at any time, especially “clear-air” turbulence, which as its name suggests, tends to arise with little or no warning. Instances of clear-air turbulence are on the rise due to the intensifying effect of climate change on jet streams, bands of strong wind that typically flow from west to east across the globe. Earth has four main jet streams: two polar jet streams near the north and south poles and two subtropical jet streams closer to the equator.

Safety expert Cox said that there are areas more prone to turbulence, mainly flight paths in the North Pacific and North Atlantic and over mountainous areas such as the Andes, Alps, Himalayas, and Rockies. Another hot spot is a band of low pressure and clouds near the equator known as the intertropical convergence zone, where the trade winds of the Northern and Southern Hemispheres converge.

As for specific flight routes, Turbli, a turbulence forecasting firm, has compiled a list of flight routes most prone to turbulence, using data from the National Oceanic and Atmospheric Administration in the United States and the United Kingdom’s Met Office.

During the past two years, the most turbulent flight was between Santiago, Chile, and Santa Cruz, Bolivia—hardly a surprise given that the route passes directly over the Andes mountain range.

The world’s most turbulent flight routes

According to turbulence forecasting firm Turbli, these are the 10 most turbulent flight routes in the world:

Within the United States, Nashville to Raleigh/Durham is most turbulent flight route, followed by the route from Charlotte to Pittsburgh.

But not all pilots think such rankings have value. Patrick Smith, a U.S. airline pilot and author of the “Ask the Pilot” blog, calls the lists “dumb” because “9 times in 10, flights along those routes will be smooth and routine.”

Are certain periods during a flight more at risk of turbulence?

Singapore Airlines flight 321 was at about 37,000 feet when extreme turbulence struck, plummeting the plane 178 feet in less than a second, but that’s not the norm, according to the NTSB study. It noted that from 2009 through 2018, about half of the turbulence-related accidents on commercial jet flights happened during the descent or approach phases, with 60 percent occurring below 20,000 feet.

Does the type of plane make a difference, and is there a part of the plane that is safer?

Smaller aircraft are more vulnerable, the NTSB data show, and within the aircraft, turbulence-related injuries are more prevalent in the aft section (the back of the plane), where more than three-quarters of injuries sustained by flight attendants occur. Flight attendants are the most at risk of all persons aboard any plane since they spend much of their time on their feet. The NTSB says that having flight attendants seated with belts fastened during additional portions of the descent phase would help reduce the number of injuries.

While both aircraft in the recent spate of incidents were manufactured by Boeing, there is no evidence to suggest any specific model within the large plane category is more prone to turbulence.

Should child safety seats be required for children under 2?

The overwhelming response from the NTSB and the safety community is a strong yes regarding child seats for babies and toddlers under 2, versus allowing them to sit with their caregivers as a “lap child.” But, for now, this remains just a recommendation, and parents are still allowed to hold a child under 2 in their lap rather than pay for an extra seat.

How often does turbulence occur, and what’s the best way to protect against it?

Extreme turbulence is still rare, as are the severe injuries that can result: 163 turbulence-related injuries were recorded in the United States between 2009 and 2022, 129 of them crew members, according to the NTSB.

Ultimately, the best protection all passengers on an aircraft have against unexpected severe or extreme turbulence is the same one it has always been: to keep their seat belt fastened while in their seats. The most recent cases support that advice. Most of the injured were unbelted or were flight attendants whose job requires them to be moving about the cabin. That’s why one of the first changes Singapore Airlines made in the aftermath of its recent ill-fated flight was to modify its in-flight seat-belt sign policies, particularly during meal service.