Severe in-flight turbulence is on the rise, according to climate researchers, and more and more flights are likely to risk posing injuries to passengers when turbulence suddenly hits.
While the worst turbulence tends to come without warning, much of it can be predicted, and the turbulence-tracking website Turbli.com gives free forecasts of a flight's turbulence from take-off to landing.
In addition to predictions of delays that headwinds might cause, the website uses data from US and UK weather services to create annual rankings for turbulence-prone airports and routes.
South America has the world's most turbulent route, Santiago to Santa Cruz, followed by Asia with the short trip between Bishkek and Almaty and the inner-China route of Chengdu to Lanzhou. In Europe, four out of five of the bumpiest routes across the continent fly to or from Zurich.
The world's most turbulent airports:
- Santiago (SCL), Chile
- Natori (SDJ), Japan
- Wellington (WLG), New Zealand
- Sapporo (CTS), Japan
- Osaka (KIX), Japan
- Bishkek (FRU), Kyrgyzstan
- Tokoname (NGO), Japan
- Lanzhou (LHW), China
- Tokyo (HND), Japan
- Christchurch (CHC), New Zealand
The world's most turbulent routes to fly:
- Santa Cruz (VVI), Bolivia - Santiago (SCL), Chile - 1,905 km
- Bishkek (FRU), Kyrgyzstan - Almaty (ALA), Kazakhstan - 210 km
- Chengdu (CTU), China - Lanzhou (LHW), China - 661 km
- Sendai (SDJ), Japan - Centrair (NGO), Japan - 517 km
- Geneva (GVA), Switzerland - Milan (MXP), Italy - 214 km
- Xianyang (XIY), China - Lanzhou (LHW), China - 519 km
- Sendai (SDJ), Japan - Osaka (KIX), Japan - 655 km
- Chengdu (CTU), China - Xianyang (XIY), China - 624 km
- Chongqing (CKG), China - Xianyang (XIY), China - 561 km
- Zurich (ZRH), Switzerland - Milan (MXP), Italy - 203 km
Turbli.com also has a map of turbulence around the world and where they occur depending on altitude. According to the website's operator, fluid mechanics engineer Ignacio Gallego-Marcos, the forecasts are based on weather models from the US weather agency NOAA and the UK's Met Office weather service.
Topography is one of the major factors in turbulence, and many of the world's most turbulent-prone air travel routes involve flights around mountain ranges.
However weather experts say turbulence can have a variety of causes, notably the jet stream, which emerges from horizontal temperature differences in the atmosphere and leads to strong fields of wind which can vary greatly in strength.
Turbulence can also be created in and around thunderstorm areas with their rising warm air and sinking cold air. When possible, pilots try to fly around them.
Most cases of turbulence are experienced only as a mild shaking in the aircraft and a slight loss of elevation. In rarer, more severe cases, passengers and crew members can be injured, however.
Especially dangerous is what's known as "clear air turbulence" since this often occurs without any advanced warning - in other words without any chance to fasten your seat belt.
According to a 2023 study from Reading University in the UK, such turbulence has been increasing over recent decades due to climate change. In 1979 clear air turbulence totalled 467 hours over the North Atlantic, while in 2020 the figure was 547 hours.
