[Peetwo]

Singapore Airlines Flight 321: Aviation accident and incident

There are many MSM and social media articles and news segments that have been running on the SQ Flight 321 CAT occurrence but IMO one of the more factual and less dramatised articles, is the following from Reuters:

The mechanics of turbulence
What happened to Singapore Airlines flight SQ321 and why?

By Adolfo Arranz, Vijdan Mohammad Kawoosa, Sudev Kiyada, Han Huang, Mariano Zafra and Simon Scarr
Published May 23, 2024  04:30 AM GMT+10

One passenger died of a suspected heart attack and many others were injured after a Singapore Airlines flight from London to Singapore hit severe turbulence on May 21, forcing the Boeing 777-300ER jet to divert to Bangkok.

The sudden turbulence occurred over the Irrawaddy Basin in Myanmar about 10 hours into the flight, the airline said. The pilot declared a medical emergency and diverted the aircraft to Bangkok, it said.

Aircraft tracking provider FlightRadar 24 said at about 0749 GMT the flight encountered “a rapid change in vertical rate, consistent with a sudden turbulence event”, based on flight tracking data.

“There were thunderstorms, some severe, in the area at the time,” it said.

Rapid movements

Altitude data from FlightRadar24 shows how the aircraft was thrust up and down over the course of a minute, before returning to its original cruising altitude of 37,000 ft.

(refer to article link to view the graphics)

During the event, the plane’s vertical speed, the rate by which the plane ascends or descends, quickly surged to 1,664 feet per minute before plummeting to -1,536 feet per minute in a matter of three seconds.

What is Turbulence?

Turbulence or pockets of disturbed air can have many causes, most obviously the unstable weather patterns that trigger storms, according to an industry briefing by European planemaker Airbus.

The resulting water particles can be detected by weather radar. Crews plan ahead by studying turbulence and other weather forecasts, which have improved over the years, loading extra fuel when needed and monitoring weather radar during flight.

What is Turbulence?

Turbulence or pockets of disturbed air can have many causes, most obviously the unstable weather patterns that trigger storms, according to an industry briefing by European planemaker Airbus.

The resulting water particles can be detected by weather radar. Crews plan ahead by studying turbulence and other weather forecasts, which have improved over the years, loading extra fuel when needed and monitoring weather radar during flight.

Other forms of turbulence can come from airflow disruptions from ground obstacles like buildings and mountains, common during takeoff and landing. On hot, sunny days over land, rising warm air and descending cooler air can also cause turbulence.

Buckling up

When an aircraft encounters turbulence and suddenly moves, anything not secured, such as passengers, can continue moving in the original direction, while the plane moves in another. Injuries from turbulence can occur as passengers are thrust towards the ceiling of the aircraft.

Photographs from the plane’s interior showed large gashes in the overhead cabin panels, gas masks and panels hanging from the ceiling and items of hand luggage strewn around. A passenger said some people’s heads had slammed into the lights above the seats and punctured the panels.




The interior of Singapore Airline flight SQ321 after it made an emergency landing. REUTERS

Unions representing U.S. airline pilots and flight attendants told Reuters the incident highlights the importance of following crew instructions and wearing seatbelt whenever seated.

But they cautioned that leaving the seatbelt sign on all the time could erode its significance, causing passengers to start ignoring it.

Among the most exposed to injury are crew who must tour the cabin to check seatbelts have been fastened when signs go on.

Airlines are required by law to switch on the seatbelt sign during takeoff and landing, but carriers have their own procedures to deal with mid-air turbulence.

Aerospace safety expert Anthony Brickhouse said passengers need to minimise their movement on flights and always stay buckled in, regardless of the seatbelt light.

A seatbelt sign always on

Some pilots and flight attendants say leaving the seatbelt sign on throughout a 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.

All modern commercial jets are designed and built to cope with forces many times those experienced in-flight, Hayes said.

But according to Swedish turbulence-forecasting website Turbli, the feeling experienced by passengers varies from plane to plane and seat to seat.

Long planes can feel most turbulent at the back and the ideal spot is around the centre of gravity, typically just ahead of the wings.

How common is it?
Turbulence-related incidents are common, according to a 2021 study by the U.S. National Transportation Safety Board.

From 2009 through 2018, it found that turbulence accounted for more than a third of reported events and most resulted in one or more serious injuries, but no aircraft damage.

Yet fatal turbulence in air travel remains extremely rare.

“It is a very unusual and rare event. As far as I can tell it is over 25 years since a passenger was killed by commercial airliner turbulence,” said Paul Hayes, director of safety at UK-based aviation data group Cirium Ascend.

The last fatal turbulence-related accident on Cirium's database involved a United Airlines Boeing 747 in 1997.

Sources

FlightRadar24; National Weather Service; Pilot Institute.

Additional reporting by

Tim Hepher, Joanna Plucinska, Rajesh Kumar Singh, Allison Lampert, Lisa Barrington and Simon Jessop

Edited by

Jon McClure, David Gregorio and Tomasz Janowski

Plus from blancoliro, via YouTube:

Hmm...wonder how long it took for the CAAS SSP to click into gear -    

SINGAPORE STATE SAFETY PROGRAM

MTF...P2