Turbulence poses an air risk and is expected to become increasingly common

Air travel and turbulence have always gone hand in hand, especially on long-haul flights. The serious episode on board a Singapore Airlines plane, in which a passenger died, raises concerns about how risky turbulence can be.

Experts say it is extremely unlikely that most flights will result in injury or damage, but there have been numerous recent incidents where this has occurred.

Understanding what causes turbulence can help aircrew and passengers mitigate its impact.

“Fortunately, deaths from turbulence on commercial flights are very rare, but unfortunately they increased by one today,” said Paul Williams, professor of atmospheric sciences at the University of Reading, in the United Kingdom, in a statement released on Tuesday (21).

See how air turbulence can create problems for air travelers.

What is turbulence and what causes it?

There are four main levels of turbulence – mild, moderate, severe and extreme.

In cases of light and moderate turbulence, passengers may feel some pressure on their seat belts and loose items in the cabin may move.

However, in more serious cases, turbulence can cause passengers to be thrown around the cabin, causing serious injury or death.

“Flight turbulence can be caused by thunderstorms, mountains and strong air currents called jet streams,” adds Williams.

“In the latter case, it is called clean air turbulence and can be difficult to avoid because it does not appear on the weather radar on the flight deck,” says the expert.

“Clean air turbulence is the movement of air created by atmospheric pressure, jet streams, air around mountains, cold or warm weather fronts, or thunderstorms,” according to the Federal Aviation Administration website.

Pilots are sometimes warned in advance about reports of turbulence by the Federal Aviation Administration, airline weather teams, or even other pilots flying ahead of them. However, turbulence can also occur without warning.

How dangerous is this?

According to the FAA, 30 passengers and 116 crew members were seriously injured due to turbulence from 2009 to 2021.

The number of air passengers is currently estimated at around four billion per year, which reveals that such incidents are still rare.

The FAA cites turbulence as the leading cause of injuries to flight attendants and passengers in non-fatal accidents on commercial airlines.

Because airlines are not required to report more minor injuries, the total number of injuries is unclear.

Fatalities, such as the Singapore Airlines incident, are also extremely rare. In March 2023, severe turbulence on a private jet resulted in the death of a former White House staffer. A December 1997 United Airlines flight from Tokyo to Honolulu also experienced turbulence that left one person dead.
“Turbulence makes flights bumpy and can sometimes be dangerous,” says Mark Prosser, a meteorology researcher at the University of Reading.

“Airlines will need to start thinking about how they will manage increased turbulence, as it costs the industry between $150 and $500 million annually in the US alone.”

“Every additional minute spent traveling through turbulence increases wear and tear on the aircraft, as well as the risk of injury to passengers and flight attendants,” says Prosser.

It is getting worse?

A study from the University of Reading reported that severe turbulence has increased by 55% over the past four decades due to the impact of climate change.

The report, published in June 2023, concluded that at a midpoint over the North Atlantic, which is one of the world's busiest air routes, the total annual duration of severe turbulence increased by 55% between 1979 and 2020.

In 2022, Williams, co-author of the study, said to CNN which believed that severe turbulence “could double or triple in the coming decades.”

He went on to attribute this to “clear air turbulence,” a type of turbulence that occurs suddenly and is very difficult to avoid.

According to data from the National Transportation Safety Board, flight crew were not warned in about 28% of turbulence-related accidents from 2009 to 2018.

Williams' analysis predicted that clean air turbulence would increase significantly around the world in the coming decades.

“Normally, on a transatlantic flight, we can expect 10 minutes of turbulence,” he added.

“I think in a few decades this could increase to 20 minutes or half an hour. The seat belt sign will be lit much brighter, unfortunately for passengers.”

Do I have to wear a seatbelt throughout the flight unless I'm going to the bathroom?

The short answer to that is “Yes”. A 2021 NTSB report indicated that the majority of passengers who were injured in “turbulence-related” crashes were not wearing seat belts. Because it is sometimes impossible to predict when an aircraft will encounter clean air turbulence, the only way to be 100% safe is to keep your seat belt fastened throughout the journey.

Does it damage aircraft?

In cases of extreme turbulence, “when the plane is thrown violently and is impossible to control,” structural damage can be caused to an aircraft, according to the U.S. National Weather Service.

Recent incidents, including the one that affected the Singapore Airlines flight, have also resulted in substantial damage to the plane's cabin.

Are some routes worse than others?

Turbulence can occur almost anywhere and at any time, but some areas are known to be more susceptible.

The Singapore Airlines flight from London to Singapore appears to have deviated from its usual route over the Andaman Sea in Southeast Asia, indicating it was close to where it encountered severe turbulence.

After an analysis of around 150,000 different flight routes, turbulence forecasting website Turbli found that the journey between Santiago, Chile, and Viru Viru International Airport, Bolivia, is the bumpiest, while the route between Almaty, in Kazakhstan, and the capital of Kyrgyzstan, Bishkek, came second on the list, released last year.