What is turbulence and why is it getting harder to predict?

This article has been updated.

“At least 30 people injured, many thrown around the cabin, one passenger apparently getting stuck in the ceiling.”

That was an excerpt from a news report on severe air turbulence experienced by people on a flight from Spain to Uruguay, which was diverted to Brazil.

According to the airline, the plane landed normally and injured passengers were taken to local hospitals to be treated. Similar stories have been making headlines, including that of a flight from London to Singapore in May 2024 on which dozens of people were injured and one died after the plane encountered severe turbulence.

Experts say air travel is still the safest form of transport, and the industry reports it continues to get safer.

At the same time, travellers are evermore likely to experience bumpier flights – and experts say climate change is to blame.

Turbulence refers to irregular air movements that affect an aircraft’s flight. It happens because of changes in wind speed and direction, commonly caused by factors including mountains, jet streams and storms.

Airlines can often predict and navigate around areas of turbulence and flight crews are trained to manage any risks to passengers during incidences.

The impact on the plane can range from a few small bumps in light and moderate turbulence to being severe enough for the plane to lose control momentarily or, in extreme turbulence, sustain structural damage.

The airline industry pays out hundreds of millions of dollars a year for related damage, delays and injuries.

While these incidents can be unsettling for passengers, serious injuries and deaths due to turbulence on large aircraft are rare, according to the Federal Aviation Administration. From 2009 to 2023, 37 passengers and 146 crew members were seriously injured because of turbulence. The number of commercial flights per year has risen in that time, from 26 million in 2009 to around 40 million today, Statista data shows.

Turbulence can take several forms, each with distinct characteristics and causes. Each type of turbulence presents unique challenges for pilots and passengers.

There is another kind of turbulence – clear-air turbulence (CAT), which is associate with wind shear. This occurs at high altitudes and in seemingly clear skies, often when rapidly moving air is close to much slower air in the jet stream. It is virtually invisible to the eye, sensors and satellites.

In 2023, clear-air turbulence caused a flight travelling to Germany from Texas, US, to suddenly drop 1,000 feet during meal service, when passengers and crew were moving around the cabin. Seven people were taken to hospital with minor injuries. It is thought this could have been the type of turbulence that affected the London-Singapore flight in May 2024.

During flights, pilots employ a variety of strategies and technologies to detect, handle, and respond to turbulence. They rely on pre-flight weather briefings, onboard weather radar systems, and real-time pilot reports from other aircraft (PIREPs) to anticipate turbulent conditions.

When turbulence is expected, pilots may adjust their altitude or route to find smoother air, communicating with air traffic control to request these changes.

Modern aircraft are equipped with sophisticated weather radar that can detect convective turbulence, allowing pilots to navigate around storm systems.

Advanced systems like IATA's Turbulence Aware network provide real-time turbulence data, enhancing pilots' ability to make informed decisions.

For clear air turbulence, which cannot be detected by radar, pilots depend on forecasts, reports from other aircraft, and their own experience.

Throughout the flight, pilots continuously monitor weather conditions, communicate with air traffic control, and draw upon their training and experience.

When encountering turbulence, pilots activate the fasten seatbelt sign, make reassuring announcements to passengers, and may reduce the aircraft's speed to minimize discomfort.

Scientists say the severity and frequency of clear-air turbulence is increasing due to climate change as warming temperatures strengthen wind shear in the jet streams. Between 1979 and 2020, the frequency of severe clear-air turbulence rose by 55% over the United States and North Atlantic Ocean, one of the world’s busiest flight routes. Moderate and light turbulence also increased.

By 2050, experts predict, pilots may be experiencing at least twice as much severe clear-air turbulence. However, it is important to note that it is rare – only a few tenths of a percent of the atmosphere has severe turbulence at any given time.

Alongside efforts to reduce global warming, including the airline industry’s direct contribution to emissions, experts emphasize the importance of improving turbulence forecasting.

The journal Nature recommends action in three areas to help the aviation industry develop predictive models and strategies in this area:

1. Using computer simulations of Earth’s atmosphere to gain a deeper understanding of air turbulence and how it is affected by climate change;

2. Developing technologies for detecting and forecasting turbulence, such making lidar, a radar using lasers that can detect clear-air turbulence, more compact and cost-effective;

3. Using artificial intelligence to optimize predictive models by training algorithms on vast air turbulence data sets. This would help spot subtle changes and complex patterns, and enhance the accuracy of predictions.

The World Economic Forum white paper Advanced Air Mobility: Shaping the Future of Aviation explores the benefits of and challenges to introducing higher levels of automation and new technological advances to the aviation industry.