CHICAGO - Buckle up. That is the message from flight attendants and pilots following the severe turbulence encountered by a Singapore Airlines flight on Tuesday that resulted in the death of one passenger and injured dozens of others.
The London-to-Singapore flight hit heavy turbulence over the Indian Ocean and descended 6,000 feet (around 1,800 metres) in about three minutes, before an emergency landing in Bangkok.
Weather forecasting service AccuWeather said satellite and lightning data showed "explosive thunderstorms" developing close to the flight path. Developing thunderstorms can leave pilots with little time to react, it said.
Airlines are required by law to switch on the seatbelt sign during take-off and landing, but carriers have their own procedures to deal with mid-air turbulence.
A witness on the Singapore Airlines flight said numerous people who were not in their seatbelt were thrown around the cabin when the plane dipped, many hitting their heads.
Meals are scattered on the floor inside the Singapore Airlines Boeing 777-300ER that encountered what the airline said was “severe turbulence”.
Singapore Airlines CEO Goh Choon Phong said the plane encountered sudden, extreme turbulence.
Sara Nelson, international president of the Association of Flight Attendants-CWA representing over 50,000 at 20 airlines, said initial reports seemed to indicate clear-air turbulence, considered to be the most dangerous type of turbulence.
Clear-air turbulence cannot be seen and is virtually undetectable with current technology, making it even more important for passengers to wear seatbelts whenever seated, she said.
"It is a matter of life and death," Nelson said.
The Air Line Pilots Association (ALPA), which represents more than 77,000 pilots at 41 US and Canadian airlines, echoed that message, saying the safest way for passengers to protect themselves is by making sure their seatbelts are always fastened.
Turbulence-related airline accidents are the most common type of accident, a 2021 study by the US National Transportation Safety Board said.
A seatbelt is pictured during a presentation by WestJet celebrating Canada's first ultra low cost airline, Swoop, at John C. Munro Hamilton International Airport in Hamilton, Ontario, Canada, on June 19, 2018. (File photo: Reuters)
Most recently, in March, a Boeing 787 plane operated by LATAM Airlines dropped abruptly mid-flight, causing injuries to more than 50 people.
Aerospace safety expert Anthony Brickhouse said passengers need to minimise their movement on flights and always stay buckled in, regardless of the seatbelt light.
American Airlines requires its pilots to turn the seatbelt sign on and instruct passengers and flight attendants to sit immediately when turbulence is severe.
Flight attendants then have to remain seated until notified by the flight's captain or the seatbelt sign is turned off. Other airlines have similar protocols.
Singapore Airlines aircraft for flight SQ321 is parked on the tarmac after an emergency landing at Suvarnabhumi International Airport, in Bangkok, on Tuesday. (Photo: Reuters)
Some pilots and attendances say that leaving a seatbelt sign on throughout the flight would backfire - as passengers would start to ignore it.
"The seatbelt sign means something, and if you leave it on all the time, it means nothing," said Dennis Tajer, a spokesperson for the Allied Pilots Association, American Airlines pilot union. "Everyone will just say it's a sign that doesn't mean anything."
