July 10: Passengers and crew on an Air China flight from Shanghai to Beijing, experienced severe turbulence about 40 minutes before landing, causing the aircraft to plummet and passengers and objects to be thrown around. The incident injured a flight attendant and a passenger, and the plane's interior suffered damage.

July 12: Flight G4-227 from Asheville to St. Petersburg, the U.S., with 179 passengers and six crew aboard, was descending toward St. Petersburg when the aircraft encountered severe turbulence, causing injuries to two passengers and two cabin crew.

July 15: Flight QK-8357 from Toronto to Windsor, Canada, with 50 passengers and four crew aboard, was en route at 3,650 meters when the aircraft encountered severe turbulence dislodging both pilots from their seats and accelerating a cart toward a flight attendant. The first officer hit his head and the cart hit the flight attendant's leg, resulting in injuries.

Many long-time frequent flyers, including this author, have noticed how flights have become bumpier over the decades. Every year sees an average 5,500 encounters with severe or greater turbulence, but that number has increased in recent years due to climate change. A recent study conducted by researchers at the University of Reading, Britain, titled Evidence for Large Increases in Clear Air Turbulence Over the Past Four Decades and published in biweekly peer-reviewed scientific journal of geoscience Geophysical Research Letters in June, suggests that clear air turbulence (CAT) has increased since 1979, aligning with the expected impacts of climate change.

But first, what actually is CAT?

Unlike the turbulence associated with thunderstorms or other weather phenomena, CAT is called "clear air" because it occurs in areas without clouds or other visible weather features. It is often encountered at high altitudes during cruising flights, typically above 6,000 meters.

CAT is caused by changes in wind speed, or wind shears, and direction within the jet stream or other high-altitude air currents. These wind shears create areas of turbulent air that can be hazardous for aircraft.

Paul Williams, a professor of atmospheric science at the University of Reading and co-author of the study, warned that unless significant action is taken, more turbulence can be expected in the coming years.

Turbulence during flights can be a discomforting experience, ranging from mild to severe cases causing damage to airplanes and injuries to passengers. With millions of people celebrating their summer vacations somewhere other than home, the study's findings are crucial and thought-provoking.

According to the recent research, CAT has become more prevalent in certain regions of the world.

The study analyzed climate data from 1979 to 2020 to examine the impact of atmospheric conditions on CAT. In the North Atlantic, an area traversed by major flight routes, severe turbulence duration increased by 55 percent over the study period, from 17.7 hours in 1979 to 27.4 hours in 2020. Moderate turbulence also rose by 37 percent, from 70 hours to 96.1 hours during the same period.

Notably, flight routes over Europe, the Middle East and the South Atlantic have also experienced significant increases in turbulence.

To manage CAT, improving forecasting is critical. Williams suggests investing in better turbulence forecasting research to enhance understanding and calculation of turbulence generation. There is also potential for technological developments, such as using light detection and ranging to detect CAT ahead of the aircraft.

The severity of turbulence is partially dependent on carbon emissions, meaning we have some control over it through emissions management. Williams reassured that although turbulence may increase, it's unlikely to reach such extreme levels that would significantly impact flying safety. Passengers are advised to keep their seatbelts fastened during flights as a precautionary measure, even if the probability of encountering severe turbulence is relatively low. 

(Print Edition Title: Turbulent Times)

The author is a Dutch aviation expert with 20 years of experience as an airport advisor, having executed related projects on five continents

Copyedited by Elsbeth van Paridon

Comments to elsbeth@cicgamericas.com