Experts explain turbulence after passengers injured on Abu Dhabi flight

Thirty-one passengers and a crew member were injured, with 10 taken to hospital, when flight EY474 from Abu Dhabi to Jakarta experienced severe turbulence.

More airline passengers may be inclined to keep their seatbelts fastened after 38 people were injured in two recent incidents of air turbulence.

As reported in The National, 31 passengers and a crew member on an Etihad Airways flight from Abu Dhabi to Jakarta were hurt, with 10 taken to hospital, when flight EY474 hit severe turbulence before landing at the Indonesian capital.

Wednesday’s incident came about three weeks after a Thai Airways flight from Jakarta to Bangkok experienced severe turbulence over Singapore, leaving six people hurt.

That both incidents involved flights to or from Jakarta raises the issue of whether parts of the world more often produce turbulence, much like some ocean areas are notoriously rough.

So what is behind incidents like these?

According to a duty forecaster at Dubai International Airport, turbulence is often caused by instability in air around a thunderstorm or air that could produce a thunderstorm. This is often seen as tall cumulonimbus clouds, typically produced in warm and moist unstable air.

“You’re looking at unstable air with up-and-down drafts within it,” he said. “If the aircraft is going through a downdraft, you would feel ­almost weightless. As soon as [the aeroplane hits] normal air, it would be a very hard bump. Multiply that a lot within a thunderstorm and that’s turbulence. It’s bumpy air.”

There is also clear-air turbulence, caused by the coming together of moving areas of air and not indicated by clouds.

The aircraft will drop when the wings – the movement of air over which generates lift to keep the aeroplane in the air – are no longer producing sufficient lift.

“So temporarily the aircraft loses life and drops, and then recovers, and drops,” said Dr Yongmann Chung, a member of the Turbulence Control Group at the University of Warwick in the United Kingdom.

In general, the forecaster said, thunderstorms were more likely in “areas where you have more hot air. If you speak about the Gulf area, you’re more likely to have thunderstorms over the Hajar Mountains”.

“You’re not very easily going to have thunderstorms over Dubai in the summer, but you certainly get them in winter.”

British Airways training captain Steve Allright said that an aircraft moves just a few feet up and down during light turbulence. Moderate turbulence, experienced for much less than 1 per cent of the time a plane is in flight, entails vertical movements of 15 feet or so, while severe turbulence, experienced by Mr Allright for just five minutes or so of his 10,000-hour flying career, involves movements of about 100 feet. As well as changing altitude to avoid mild turbulence, pilots can alter course and fly around areas of instability