73-year-old Geoff Kitchen from Gloucestershire died from a suspected heart attack in the aftermath of the incident, which launched passengers and staff into the ceiling and left more than 100 needing hospital treatment. Photos from the cabin showed a scene of chaos, with oxygen masks and panels hanging from the ceiling, and passengers’ meals and possessions strewn across the floor.
The fatal incident on 21 May is not the only time extreme turbulence has made headlines recently. Less than two weeks later, 12 people were injured on a flight from Doha to Dublin when it hit turbulence over Turkey, while seven people were injured when a Lufthansa flight was affected above Tennessee last year.
Although turbulence that causes serious injuries and deaths is thankfully very rare, it could become a growing issue in the coming years due to climate change. 2023 research by the University of Reading found that clear-air turbulence, which is invisible and hazardous to aircraft, has increased significantly in recent decades as air has warmed.
At a typical point over the North Atlantic – one of the world’s busiest flight routes – the annual duration of severe turbulence increased by 55% from 17.7 hours in 1979 to 27.4 hours in 2020, the research found. Moderate turbulence increased by 37%, while light turbulence increased by 17%.
The study found that other busy flight routes over Europe, the Middle East and the South Atlantic also saw significant increases in turbulence.
“Turbulence makes flights bumpy and can occasionally be dangerous,” said PhD researcher Mark Prosser. “Airlines will need to start thinking about how they will manage the increased turbulence, as it costs the industry $150–500m annually in the USA alone. Every additional minute spent travelling through turbulence increases wear-and-tear on the aircraft, as well as the risk of injuries to passengers and flight attendants.”
Investment is needed to improve turbulence forecasting and detection systems, said co-author Professor Paul Williams. While meteorological conditions and flight route ultimately determine whether or not a plane is likely to hit turbulence, some engineers hope to provide solutions that could avoid or dampen its impact and protect passengers and crew.
Austrian firm Turbulence Solutions says its patented ‘turbulence cancelling’ technology can reduce turbulent loads felt by passengers by more than 80%, while also minimising use of additional fuel to avoid turbulent air.
The technology combines several approaches to stabilise aircraft. First, it uses pressure sensors or ‘wind Lidar’ to anticipate upcoming turbulence. Those measurements are fed into a processor, which feeds differential control pulses to small ‘flaplets’ built into flaps on the wing, dynamically changing the wing shape to counteract the effect of the turbulence.
The technology has only been used so far in light aircraft, but the company aims to introduce it on large aircraft in future – although, as with any new technology, development and certification will likely take some time.
Referring to an incident of severe turbulence on an Emirates A380 flight from Perth to Dubai, the company wrote: “Although our turbulence cancelling system cannot completely erase these severe effects, it can at least mitigate them to the extent that no one is harmed. And during the rest of the flight, passengers on aircraft with the turbulence cancelling system enjoy unparalleled flight comfort.”
Other projects have taken a different approach. A scheme at NASA, for example, focused in on the infrasound signature (sounds too low to be heard by humans) of clear-air turbulence to help air traffic controllers and pilots plot alternate routes.
Researchers developed an infrasound microphone with a low-tension diaphragm across a wide radius, enabling it to pick up low frequencies with high fidelity. On the ground, the microphones could pick up and locate turbulence more than 300 miles away.
The sensors were also tested on Hidron, an uncrewed stratospheric glider from Canadian company Stratodynamics Aviation. The microphones were reportedly able to isolate the low frequencies of turbulence even as the wind whipped past.
“The team hopes the data provided by the infrasonic microphone will become ubiquitous in detecting and forecasting turbulence, air traffic control decision-making, and aviation route planning,” a NASA announcement said. “By making it easier to avoid turbulence in all parts of the flight, less fuel is wasted in navigating around turbulent air, and less carbon dioxide is released into the atmosphere.”
Airframes themselves could be considered for optimisation in future if turbulence increases as predicted. Research at the University of Bristol and the Royal Veterinary College found that bird wings act like a ‘suspension system’ as they fly through turbulence, rotating around the shoulder joint to stay level. Such a technique could be replicated in future aircraft to minimise the effect of turbulence.
Want the best engineering stories delivered straight to your inbox? The Professional Engineering newsletter gives you vital updates on the most cutting-edge engineering and exciting new job opportunities. To sign up, click here.
Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.