As a Delta flight from Salt Lake City to Amsterdam began to shake violently last week, some passengers feared the plane was about to crash.
The aircraft encountered extreme turbulence, hurling passengers
into the ceiling and tossing service carts through the cabin. One traveller described the experience as feeling like an earthquake. The flight was diverted for an emergency landing in Minneapolis, where 25 people were hospitalised.
This was the latest in a string of recent turbulence-related incidents that have led to injuries, hospitalisations, and even a fatality. Last year, a 73-year-old man suffered a fatal heart attack during intense turbulence on a flight from London to Singapore, CNN reported.
Turbulence, caused by disturbances in the atmosphere, is one of the most unpredictable weather phenomena for pilots.
Air moves much like water flowing through a river—smoothly when undisturbed, but turning turbulent when it meets obstacles. Just as rocks disrupt a river’s flow, mountains and storms disrupt the airflow, creating turbulence.
Moderate to extreme turbulence occurs tens of thousands of times globally each year. While most passengers experience it as minor jolts, severe turbulence can lead to structural damage, brief loss of control, and passenger injuries. Between 2009 and 2024, turbulence resulted in over 200 serious injuries in the US alone, according to data from the National Transportation Safety Board.
The good news is that fatalities are very rare, and wearing a seatbelt almost always prevents serious injury. The bad news: Turbulence appears to be increasing, especially on some of the most heavily trafficked routes, and it’s set to get worse as the planet heats up.
The turbulence forecasting site Turbli has examined over 10,000 flight routes, drawing on data from sources such as the National Oceanic and Atmospheric Administration and the UK Met Office, to identify and rank the world’s most turbulent air routes.
The goal is “to show people that even if turbulence is chaotic, it does follow some patterns,” CNN quoted Ignacio Gallego Marcos, Turbli’s founder and an expert in computational fluid dynamics, as saying.
The 120-mile stretch between Mendoza, Argentina, and Santiago, Chile, boasts stunning views of the towering, often snow-covered Andes Mountains—but it also ranks as the world’s most turbulent flight route, according to data from Turbli.
Mountain ranges act as massive, immovable barriers that disrupt the flow of air, generating atmospheric waves that can travel for hundreds of miles. When these waves break, they produce intense turbulence, much like ocean waves crashing into foamy surf, explained Gallego Marcos.
The majority of the 10 most turbulent routes in the world involve mountains, including the Andes, the longest land-based mountain chain on Earth, and the Himalayas.
In the United States, the roughest flights are typically those crossing the Rocky Mountains, particularly routes to and from Denver and Salt Lake City. A similar pattern is seen in Europe, where many of the most turbulent journeys pass over the Alps, with planes travelling between France, Italy, and Switzerland, according to Turbli.
Pilots are well aware of the need for extra caution when flying over mountains, but the turbulence generated in these areas isn’t always predictable. It can be triggered by “very small-scale features of the mountain” that forecasts don’t always detect, explained Gallego Marcos.
