Severe turbulence caused by developing storms over the Irrawaddy Basin on May 21 shook up Singapore Airlines’ flight SQ321 as crew carried out meal service and passengers took the opportunity to stretch and take a toilet break.

Dozens of passengers and crew members were injured – with one fatality, a 73-year-old passenger with a heart condition – as the aircraft experienced an altitude drop of 178 feet (about 54m) in 4.6 seconds. An emergency landing had to be made at Bangkok’s Suvarnabhumi Airport.

Days later, 12 passengers on Qatar Airways flight QR017 from Doha to Ireland were injured during a bout of turbulence over Turkish airspace. The airline reported that the injuries were minor, and the aircraft was able to land safely and on schedule in Dublin.

Soon after, a crew member on Turkish Airlines’ flight TK2320 injured her spine during severe turbulence enroute from Istanbul to Izmir.

Aviation experts weighing in on the accidents said such fatalities are rare and that flying remains a safe way to commute over long distances.

Independent aviation analyst Alvin Lie said the intensity of turbulence experienced by SQ321 was likely “extreme”, and that the phenomenon was rarely severe.

Stefan Wood, executive director at Air 7 Asia and pilot, who has flown in the Asian region for the past 20 years, agrees that SQ321’s incident was unfortunate, and flying remains safe.

“Pilots in flight face turbulence associated with clear-air and convective weather such as thunderstorms. In the case of CAT (clear-air turbulence), the aircraft can drop a couple of thousand feet all of a sudden. This will cause anything not buckled down to go flying,” Wood told TTGmice.

Wood pointed out that the intensity of turbulence varies by aircraft size and flying altitude. Generally, larger aeroplanes are more stable while higher altitudes offer a more stable environment. “The worst weather happens between 20,000 and 40,000 feet,” he said.

Larger passenger jets typically fly at a maximum altitude of about 41,000 feet, whereas smaller private jets can go farther up to a maximum of 53,000 feet.

“To explain this simply, larger aircraft have to pressurise a larger cabin space, and it gets harder to pressurise at higher altitudes. Conversely, smaller private jets have less cabin space to pressurise and can fly at higher altitudes,” said Wood.

Turbulence on the rise?
Social media chatter seems to paint a picture of flights encountering more frequent and intense turbulence.

Anecdotal feedback from conversations this TTGmice journalist had with air crew during both long- and mid-haul flights taken since the start of this year also indicated more frequent turbulence in the past year, with small accidents becoming commonplace.

An editorial authored by Yann Cabaret, CEO of SITA for Aircraft, and published in July 2023 on the SITA site, stated that climate change has resulted in a rise in extreme weather events, which have a significant impact on aviation operations, including flight delays, and compromised safety of passengers and crew members.

Research published in June 2023 by the University of Reading showed a significant increase in CAT over the past four decades due to the warming climate, particularly in the US, the North Atlantic, South Atlantic, Eastern Pacific, Europe and the Middle East.

He said CAT was “invisible and difficult to forecast ahead of a flight”, especially not by traditional onboard radar systems. To achieve more accurate weather visualisation, SITA eWAS and SITA Mission Watch were developed to aggregate multiple weather feeds.

All airlines are equipped with updated weather radar systems, said Subhas Menon, director general of the Association of Asia Pacific Airlines, but the severity of the Singapore Airlines accident would encourage airlines to review their onboard equipment and reconsider safety measures.

Indeed, the airline has now updated its service routine during turbulence. When the seat belt sign is on, both meal and hot beverage services will be suspended, and crew will also have to be seated with their selt belts secured.

Costlier to fly
Witsanu Attavanich, associate professor of economics at the Faculty of Economics at Kasetsart University in Bangkok, Thailand, warned that there is a cost to flying in increasingly turbulent skies.

“Planes may need to carry more spare fuel to circumvent turbulence. Disruptions due to turbulence can lead to flight delays, cancellations and lost revenue. It can also damage aircraft, leading to repair costs and downtime, or contribute to passenger reluctance to fly,” he added.

The industry would also likely need to invest more money into technologies such as improved forecast models, advanced detection systems, and sensor development to better identify and circumvent turbulence, particularly CAT, he said. – Additional reporting by Anne Somanas