Turbulence on the rise

In late August United Airlines Flight 880 from Houston to London Heathrow experienced severe turbulence, throwing some of the 200+ passengers and crew onto the aircraft’s ceiling and resulting in 23 people being injured. One pasenger described it as being like a smooth flight suddenly hit by something like a torpedo.

The Boeing 767-300 made an emergency landing at Shannon airport and although no one was seriously hurt the incident highlights the danger of turbulence and the fact that some experts predict it will get more and more commonplace and severe.

Royal Society research fellow and professor at the University of Reading's National Centre for Atmospheric Science Dr Paul Williams says that there will be an increase in severe clear-air turbulence incidents in years to come, as climate change takes its effect in the stratosphere.

Such turbulence typically appears suddenly without warning - clear-air turbulence is especially difficult to avoid, because it cannot be seen by pilots or detected by satellites or on-board radar - and incidents have steadily increased in the past few decades.

As carbon dioxide levels in the atmosphere increase

Worldwide, turbulence is the cause of dozens of fatalities annually on small private planes and hundreds of injuries to passengers in bigger aircraft, and as carbon dioxide levels in the atmosphere increase, so will the numbers of incidents.

One of the studies showing an increase in turbulence was by the US Federal Aviation Administration in 2006, which reported that the number of incidents where turbulence caused serious accidents in American flights more than doubled between 1982 and 2003, even bearing in mind the rise in numbers of flights during that time.

A report published in 2014 by the Australian Transport Safety Bureau relating to flights in Australian air space also suggested that cases of turbulence had risen sharply.

Williams’ own research suggests that the jet stream could become 15 per cent stronger as a result of rising temperatures, making some flights longer and others shorter, but also potentially making conditions too turbulent for travel at certain times. Longer flight times can considerably increase airline running costs: each extra two minutes in the air is thought to use approximately 100 gallons of fuel per aircraft on average and cost an additional $20 million annually.

Disruption from turbulence already costs more than $500 million

Not everyone is convinced that turbulence is increasing substantially overall, or whether climate change is the culprit. For example, figures from the UK air travel regulator, the Civil Aviation Authority, and also the European Air Safety Agency, have not shown significant changes in turbulence incidents in recent years. However, turbulence is a localised phenomena affected by jetstreams and other meteorological conditions, which vary greatly around the world.

In America alone it is estimated that annual disruption from turbulence already costs more than $500 million. Williams suggests that to reduce incidents, limiting carbon dioxide emissions would obviously help, along with advancing the science of turbulence prediction and improving meteorological forecasting to predict turbulence.

Systems to effectively detect turbulence are being developed, such as a technique where ultraviolet light is shined along a plane’s path, with the reflections that come back helping identify approaching turbulence. And manufacturer Rockwell Collins has developed a new weather radar featuring two levels of turbulence detection, ‘severe’ and ‘ok to fly’.

However, comprehensively fitting aircraft with such systems would cost the air travel industry more than the current cost of turbulence, so the incentive to invest in it is not yet there. But perhaps the industry will think again as turbulence increases.