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20/21MAY24 SQ321 LHR-SIN diverts to BKK [due to severe turbulence]

20/21MAY24 SQ321 LHR-SIN diverts to BKK [due to severe turbulence]

Old May 21, 2024, 8:13 am
  #61  
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Source + video on Dutch public news: NOS
https://nos.nl/artikel/2521298-dode-...apore-airlines


NOS : an official source of the Dutch government
https://en.wikipedia.org/wiki/Nederl...roep_Stichting


Translated from Dutch to English:
Spoiler
 
I've flown AMS- SIN many times and indeed above the bay of Bengal,
it is sometimes a bit wobbly.
Sometimes one needs to hold one's glasses / cups, (against a spill)
sometimes fasten your seatbelt with & "hot beverages service will be suspended "
& sometimes "flight attendent be seated" and the pilots over the PA system annoucing the effect / duration / cause.
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Last edited by HadesNL; May 21, 2024 at 7:23 pm Reason: Interpunction and quote source
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Old May 21, 2024, 8:16 am
  #62  
 
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The Flightaware tracklog shows a period of around 90 seconds between 07:48:54 UTC and 07:50:25 UTC during which the aircraft drops ~23m, climbs ~114m and then drops back ~91m to its cruising level, Latitude and Longitude positioning data puts the aircraft over Myanmar at the time. (Times are shown as British Summer Time which is 1 hour ahead of UTC)

https://uk.flightaware.com/live/flig.../VTBS/tracklog


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Old May 21, 2024, 8:32 am
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WSJ is reporting that it was a British National who likely died from cardiac arrest.

https://www.wsj.com/business/airline...hare_permalink
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Old May 21, 2024, 8:34 am
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Originally Posted by AJNEDC
How about diverting around such severe turbulence? [conjecture deleted by moderator]
Airlines and the industry have worked for years on turbulence prediction software and changes to radars to allow them to seek turbulence (Doppler radar, similar to used to track tornados, etc), but the basic problem is they are literally shooting at a moving target. If the airliners radar is tilted slightly incorrectly it may not detect the air movement, and the movements that will cause issues can vary in relation to flight paths.

The most difficult turbulence is CAT (clear air turbulence), and is most often associated with jet cores and the shear areas between wind levels/directions. The jet core is literally a pipe of fast moving air with a turbulent boundary layer around it in three dimensions, so when you cross this moving river of air, the eddies you see on river banks are the turbulence you hit in the air.

Air Traffic Control records, reports and advises of such area of turbulence, but the severity can vary massively based upon position and altitude, so itís very much a hit and miss thing, which is why flight crews are conservative in keeping the seat belt sign on. Itís passengers that disregard that sign, and especially their habits of having loose items around them, that endanger other passengers and crew.
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Old May 21, 2024, 8:53 am
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Impressive that these planes can take such abuse and still stay intact.
been in bad turbulence and people were fearful that the wings would come off
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Old May 21, 2024, 8:55 am
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Originally Posted by Swanhunter
4 pilots for LHR-SIN, and SQ have a good cabin crew staff ratio
And wouldn't there be extra FAs to allow rest anyway?

Also, NYT article with some additional details https://www.nytimes.com/2024/05/21/w...nce-death.html as well as statements from Singapore Airlines and its Minister of Transport.
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Old May 21, 2024, 8:57 am
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Passenger nationality info released by SQ, according to the Straits Times.

Here's the latest SQ release:
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Old May 21, 2024, 9:07 am
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southlondonphil

I think you may be right, in that this was the point the plane ran into the CAT.

The much quoted 6,000 ft 'drop' occurred at a point in time where the aircraft was already heading towards BKK (110 degree heading) vs the normal heading it would have taken to get to Singapore of (130-140 degrees). Also as others have said, the 6,000 ft 'drop' occurred over a longer period unlikely to have caused the amount of damage we've seen.

Originally Posted by Greenpen
Different figures about the drop are being stated in different places but using one, 6000 feet in 3 minutes that would be about 23 mph. I seem to remember that your muscles cannot brace or restrain you at that speed even if you are anticipating it. Given that force might have fluctuated wildly it can imagine anything not very firmly attached would take to the air with little that could be done about it.
I think as per southlondonphil reply, the plane ran into CAT prior to this - probably 10 minutes prior. By the time the 6,000 feet 'drop' occurred, the plane was already firmly heading towards BKK, so therefore it was probably a controlled descent for landing.

I think credit probably needs to go to the flight crew for assessing the situation and declaring an emergency and diverting to BKK promptly. Looked like between the initial incident to the time the plane diverted and started making the controlled descent all happened within 10 minutes.
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Last edited by NewbieRunner; May 21, 2024 at 11:43 am Reason: Merged two posts to reduce post count for a new member.
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Old May 21, 2024, 9:12 am
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Originally Posted by TxDucky
Airlines and the industry have worked for years on turbulence prediction software and changes to radars to allow them to seek turbulence (Doppler radar, similar to used to track tornados, etc), but the basic problem is they are literally shooting at a moving target. If the airliners radar is tilted slightly incorrectly it may not detect the air movement, and the movements that will cause issues can vary in relation to flight paths.

The most difficult turbulence is CAT (clear air turbulence), and is most often associated with jet cores and the shear areas between wind levels/directions. The jet core is literally a pipe of fast moving air with a turbulent boundary layer around it in three dimensions, so when you cross this moving river of air, the eddies you see on river banks are the turbulence you hit in the air.

Air Traffic Control records, reports and advises of such area of turbulence, but the severity can vary massively based upon position and altitude, so itís very much a hit and miss thing, which is why flight crews are conservative in keeping the seat belt sign on. Itís passengers that disregard that sign, and especially their habits of having loose items around them, that endanger other passengers and crew.
Thank you for the detailed explanation. Much appreciated.
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Old May 21, 2024, 9:16 am
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Originally Posted by Stratoliner777
Horrible and sad news. Hopefully everyone who was injured recovers and that there are no additional fatalities.

[Comment removed by mod]

Saw a posting elsewhere that turbulence is common around the Bay of Bengal, so much so that SQ flights may regularly suspend meal service at certain points -- true???
The Bay of Bengal and the Andaman Sea are notorious at this time of the year because of the monsoon.
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Old May 21, 2024, 9:18 am
  #71  
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Per NY Times, one dead (died on board) thirty injured:
A 73-year-old man from Britain died and seven people were critically injured after a plane encountered severe turbulence on a flight from London to Singapore, officials said on Tuesday.

The plane, a Boeing 777-300ER operated by Singapore Airlines, was diverted to Bangkok, the airline said in an announcement on social media, and landed at 3:45 p.m. local time on Tuesday.

In all, 30 people, both passengers and crew, were injured, officials said. The airline said in a statement that 18 people had been hospitalized and another 12 people were being treated for injuries. “The remaining passengers and crew are being examined and given treatment, where necessary, at Suvarnabhumi International Airport in Bangkok,” the airline said.
https://www.nytimes.com/2024/05/21/w...nce-death.html

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Old May 21, 2024, 9:35 am
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Originally Posted by SK AAR
I know it is OT, but 18 crew members?

I would expect 3 pilots and 10-11 FAs - or I'm completely wrong for SQ flights?
IIRC, the minimum crewing requirement for a 77W is 10 or 11 cabin crew (not counting pilots). That is mandated by Singapore civil aviation authority I believe to operate the flight even if only 10-20 pax were onboard (happened during Covid). So with over 200 pax, the number of FAs needed would have increased. Add at least 3 pilots, sometimes 4 and 18 crew sounds about right.
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Old May 21, 2024, 9:40 am
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I hazard a guess it's 10 min. crew. (1 per door)

4 pilots, 3 in F, 5 in J and 6 in Y I think.
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Old May 21, 2024, 9:47 am
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Originally Posted by NaKaTaTuNa
I think as per southlondonphil reply, the plane ran into CAT prior to this - probably 10 minutes prior. By the time the 6,000 feet 'drop' occurred, the plane was already firmly heading towards BKK, so therefore it was probably a controlled descent for landing.

I think credit probably needs to go to the flight crew for assessing the situation and declaring an emergency and diverting to BKK promptly. Looked like between the initial incident to the time the plane diverted and started making the controlled descent all happened within 10 minutes.
Definitely, a real, sudden 6,000 ft drop (thats close to 2,000m) would have been a much, much more serious issue and incident paralleling "free fall" and such severe stress can push a plane to it's limits or beyond. Even an emergency decent of an aircraft, e.g. in case of full loss of cabin pressure, to around FL10 (to get to an altitude with breathable air) would not be so sudden, but rather rapid though still a controlled descent by flight crew within the capabilities and limitations of the aircraft.

Many of these internet sources are of questionable quality and accuracy on the best of days so it is important to fact check. This is not a criticism on the FT poster I quoted, just to be clear, rather I echo such sentiments expressed by other posters.

Last edited by demue; May 21, 2024 at 9:59 am
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Old May 21, 2024, 10:00 am
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Originally Posted by demue
Definitely, a real, sudden 6,000 ft drop (thats close to 2,000m) would have been a much, much more serious issue and incident paralleling "free fall" and such stress can rip a plane apart. Even an emergency decent of an aircraft, e.g. in case of full loss of cabin pressure, to around FL10 (to get to an altitude with breathable air) would not be sudden, but rather rapid though still a controlled descent by flight crew within the capabilities and limitations of the aircraft.

Many of these internet sources are of questionable quality and accuracy on the best of days so it is important to fact check. This is not a criticism on the FT poster I quoted, just to be clear, rather I echo such statements by other posters.
Agreed. A 75-feet drop over 30 seconds is a lot more damaging (and fits the evidence more) than a 6,000 ft controlled descent over the duration of a few minutes, particularly when passengers are not expecting the drop. But a lot less headline grabbing I suppose?
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