Responding to the sad news that a passenger was killed onboard a plane that was affected by turbulence, Professor Paul Williams, University of Reading, said that turbulence fatalities on commercial flights are fortunately very rare, but have sadly increased by one today.

"Turbulence on flights can be caused by storms, mountains, and strong air currents called jet streams.  In this last case, it is called clear-air turbulence, and it can be difficult to avoid because it doesn't show up on the weather radar in the flight deck," he said.

"A detailed analysis of the meteorological circumstances and the particular type of turbulence that caused today's fatality will take some time."

Singapore Airlines said the flight encountered “sudden extreme turbulence” over Myanmar’s Irrawaddy Basin at 37,000 feet about 10 hours after departure, with the pilot declaring a medical emergency and diverting the plane to Bangkok.

One of the passengers on board Flight SQ321 to Singapore said the plane suffered a “dramatic drop”, meaning people not wearing a seatbelt were “launched immediately into the ceiling”.

Professor Williams continued: "The last fatality caused by clear-air turbulence on a commercial flight occurred on 28 December 1997, on a United Airlines flight from Tokyo to Honolulu.  Other forms of turbulence have caused more recent fatalities, but as far as I am aware there has not been a turbulence fatality on a commercial flight since 2009.

"We now have strong evidence that turbulence is increasing because of climate change."