Turbulence is, without a doubt, what nervous fliers (around one in 10 of us) fear most when they board an aircraft. It is the most common cause of injury to air passengers.

So a report [embedded below] published this week by the Australian Transport Safety Bureau (ATSB), suggesting that cases of turbulence had risen sharply, is bound to raise a few heart rates. The ATSB said incidents doubled over the three-month period between October and December last year, compared to the previous quarter.

Dr Stuart Godley, head of the ATSB’s Aviation Research Team, would not speculate on what had caused the rise, but described it as “unprecedented”.

“During the last five years there has been an increase in reporting, particularly from cabin crew, about an increase in turbulence, but we don’t know why this is occurring,” he said. “Because they are weather-related, these events are cyclical. We’re used to seeing more of them in summer, but this increase is unprecedented.”

He added that some areas of the country, such as Sydney and the Gold Coast, were more prone to turbulence. “122 incidences of turbulence were recorded, 35 of which occurred on flights in to and out of Sydney, which seems to be a hotspot,” he said.

While the figures relate to flights in Australian air space, there have been several high-profile cases elsewhere in the world recently. Last month several passengers were injured when a United Airlines flight from Denver to Billings, Montana, experienced severe turbulence, while 39 fliers were injured on a bumpy Thai Airways flight from Bangkok to Hong Kong last summer.

There is one silver lining for nervous fliers. While clear-air turbulence cannot be accurately detected by airlines, that could change.

New technology – called DELICAT (Demonstration of LIDAR based Clear Air Turbulence detection), which uses lasers to measure air density, was recently tested by the German Aerospace Center.

And last month, manufacturer Rockwell Collins unveiled a new weather radar that features two levels of turbulence detection – “severe” and “ride-quality”. American Airlines is expected to become the first carrier to trial it.

So if turbulence is becoming more common – it may soon be more easily avoided.

Figures from the Civil Aviation Authority (CAA), Britain’s air travel regulator, would suggest that cases of turbulence may have risen slightly over the past decade. In the last five years – 2009-2013 – there were a total of 387 turbulence-related injuries to passengers flying with a British airline, compared to 213 in the previous five. However, those figures are skewed by one year – 2010 – when 147 injuries were reported, and last year only 32 passengers were hurt – the lowest number since 2006.

Figures from the European Air Safety Agency (EASA) do not chime with the ATSB’s report, either. It said that 16 injuries due to turbulence were reported last year, compared with 23 in 2012, 28 in 2011, 17 in 2010 and 72 in 2009. However, the low number of injuries reported – less than the CAA’s – would suggest that its figures are hardly comprehensive.

“It is difficult to judge if an increase in the number of turbulence reports also reflects an increase in the number of times they actually occur,” said an EASA spokesperson, referred to the ATSB’s claims. “The reason is that as safety culture further improves and reporting systems improve, so does reporting. In other words the increase in the number of reports may also be the result of better reporting.”

Figures from The Federal Aviation Administration, meanwhile, the US equivalent of the CAA, would also suggest that cases of turbulence remain steady. It said 24 people were injured due to turbulence in 2013. During the previous decade, the average number of injuries was 36 per year.

So is it an Australian phenomenon? Last year Australia experienced its hottest year on record, according to the country’s Bureau of Meteorology. Considering thermals – where heat from the sun makes warm air masses rise and cold ones sink – is the main cause of turbulence, it seems logical to assume this is a factor, although the ATSB did not mention this in its report.

So could global warming cause more turbulence in future? Last year Dr Paul Williams of the University of Reading’s National Centre for Atmospheric Science, suggested exactly that . He claimed that global warming could destabilise air currents at altitudes used by commercial airliners.

“Climate change is not just warming the Earth’s surface, it is also changing the atmospheric winds 10 kilometres (six miles) high, where planes fly,” he said. “That is making the atmosphere more vulnerable to the instability that creates clear-air turbulence. Our research suggests that we’ll be seeing the ‘fasten seatbelts’ sign turned on more often in the decades ahead.”

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Photo Credit: Authorities in Australia are reporting an "unprecedented" increase in turbulence incidents. Pictured, a KLM Boeing 747-400 plane lands at Los Angeles Airport. Nicholas Burningham / Associated Press/Alamy