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Severe turbulence LHR-SIN. One dead.

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Severe turbulence LHR-SIN. One dead.

Old 21st May 2024, 20:29
  #101 (permalink)  
 
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Did anyone follow (Flightradar etc) the route. Anyone pick out an A380 flying in front or crossing its path? Or another large aircraft? Not saying this is what caused the upset, but flying through the wake of a 380 certainly wakes you up! Believe me!
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Old 21st May 2024, 20:49
  #102 (permalink)  
 
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Originally Posted by happyjack
Well I do not intend to insult anyone here so if you find my comment insulting please disregard?
I assume you are on the 747 and of course fuel is more an issue to a mere GV?
However I have experienced hundreds of situations with airlines whereby we are sitting in unpleasant turbulence for lenghty periods, (many hours) and no attempt being made to improve the situation?
Of course it is not always possible due ATC restraints, other traffic, etc. but I cannot help to think the crew just cannot be bothered with trying to find an alternative a lot of the time?
I have flown the same routes as the world's airlines and 95% of the time I have found an alternative to getting tossed around! We don't always fly in the 40's, many times in the high 30's so mixing with all traffic.
If your operation constrains you to such a point where you cannot go up or down a few thousand feet to make things a bit more safer and confortable I am truly glad I got out of the airlines after just 3 unpleasant years there!
Those three unhappy years didn't teach you much about heavy jet performance! To think that the big ones can "just pop up or down a few thousand feet to check out the turbulence " is naive and shows a significant gap in knowledge.
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Old 21st May 2024, 21:02
  #103 (permalink)  
 
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BBC News still peddling the "plunged 6,000 feet" nonsense.
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Old 21st May 2024, 21:17
  #104 (permalink)  
 
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Originally Posted by Skipness One Foxtrot
As a data analyst, we would expect the pre and the post measurement periods to be measured in the same way. Of course the early days of flying have a lot less flights and meausrements were made less frequently and with less reliable instruments. For example the diagnosis of autism has exploded mainly because Doctors know what they're looking for, rather than there being more autistic people. "Scientific experts" can be bought and sold depending where the funding goes. I know, I work in the field.
I share your scepticism, or at least doubt, regarding CAT specifically.
I have been wondering how I would tackle an investigation into the possibility that CAT has increased ........... it rapidly becomes a mess of definitons, units, periods, distances, reporting protocols .
I worked closely with the Met. Office leading experts in their field, before Climate Change became a free lunch.

Last edited by langleybaston; 21st May 2024 at 21:28.
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Old 21st May 2024, 21:24
  #105 (permalink)  
 
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Originally Posted by DaveReidUK
BBC News still peddling the "plunged 6,000 feet" nonsense.
BBC TV News has been hilarious today. I assume B777s use VNAV Plunge Mode if requesting lower due to turbulence?
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Old 21st May 2024, 21:52
  #106 (permalink)  
 
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Originally Posted by zegnaangelo
I for one keep my seat belt fastened when seated. just a prudent thing to do.

but my philosophy is if the seatbelt sign is kept on for too long and if one needs to go to the loo, the one needs to go, especially if there are children involved. don't think it's reasonable to strap someone in their seat for say 30mins or more, esp if they are busting and fhe alrernative is perhaps turbulence injury or soiled clothing. This is of course if I see cabin crew still going about their service.

Only exception to this is when cabin crew are ordered back to their stations... you then know it's very serious. then again I have not seen this happen for a prolonged amount of time.

On this note why are cabin crew generally allowed to move about when the seat belt sign is on? are their heads made of harder material or something 🤔 😅😭
My old mob required an announcement from the flight deck when the seatbelt sign was put on to the effect that all pax and cabin crew were required to take to their seats and fasten seat belts. Trolleys away and a check to ensure pax compliance and then cc sat down. If ‘immediately’ was included, then trolley wheels locked, and cc went to the nearest seat, including pax seats.
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Old 21st May 2024, 22:23
  #107 (permalink)  
 
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Originally Posted by ZFT
I doubt many will argue with that but enforcement will be a headache for the cabin crews.
Originally Posted by EXDAC
How does this proposed system detect that the belt is round the person in the seat?
I did consider that possibility, If a passenger is stupid enough to deliberately circumvent a safety system or device, then they should probably be banned from flying again with the same airline.
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Old 21st May 2024, 22:56
  #108 (permalink)  
 
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Originally Posted by ANOpax
I am a little bit staggered but not surprised at the comments by you on here peddling the climate change scam.

If you had bothered to read the report that you quote, you'd have discovered that there has been no increase in observed turbulence, only modelled turbulence which is about a reliable as modelled infection rates...

The NTSB keeps records of accident events where turbulence is reported and it shows no statistically significant increase. If the outlandish claims of a 55% increase in CAT made in the Reading University report were true then we wouldn't be looking at an essentially flat graph.
According to the NTSB, the majority of injuries occur below 20,000 feet in the vicinity of thunderstorms.


Turbulence and non-turbulence-related Part 121 accidents in the U.S. from 1989 to 2018. U.S. National Transportation Safety Board.

Looks like a trend to me. % of accidents turbulence related going from 12 to 32.
If it was a share price graph it’s nearly a ‘three bagger’. 😁
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Old 21st May 2024, 23:18
  #109 (permalink)  
 
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Originally Posted by mikegss
I've heard people on flights saying to their neighbours "he's probably forgotten to turn the sign off".
I have disembarked more than once with the seat belt signs still illuminated. It certainly happens.

It isn't helped by the fact the cabin crew are allowed get up and put their trolley out while the signs are still on. The messaging here is very confused.

Plane seats are small and uncomfortable, people are warned about DVT. Many now stand up for much of a short haul flight. There are often queues for toilets, people have hot drinks on tables. In premium classes they are paying for beds and armchairs, they certainly don't want to be buckled up for the duration. They are allowed to bring on huge cases they can scarcely lift and open the lockers during a flight to access the contents.

Do any of these lockers manage to stay closed during turbulence incidents? Why is such a failure of basic purpose tolerated?
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Old 21st May 2024, 23:29
  #110 (permalink)  
 
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Originally Posted by Skipness One Foxtrot
As a data analyst, we would expect the pre and the post measurement periods to be measured in the same way. Of course the early days of flying have a lot less flights and meausrements were made less frequently and with less reliable instruments. For example the diagnosis of autism has exploded mainly because Doctors know what they're looking for, rather than there being more autistic people. "Scientific experts" can be bought and sold depending where the funding goes. I know, I work in the field.
Given that the real challenge here is that apparently nobody knows where the turbulence is until they actually hit the turbulence, makes it rather difficult to quantify?
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Old 21st May 2024, 23:31
  #111 (permalink)  
 
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I agree the stories aren't matching up. There is waffle about severe or extreme turbulence, but no actual descriptions of turbulence. Particularly that testimony does sound like a stall, or some other sort of Boeing tom-foolery. There is lots of damage to the overhead lockers, presumably from the impact of pax heads, but if there was severe turbulence where are the burst or broken overhead lockers and strewn baggage?
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Old 21st May 2024, 23:37
  #112 (permalink)  
 
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Originally Posted by EXDAC
How does this proposed system detect that the belt is round the person in the seat?
It doesn't. Already exists on cars and they just sit on the belt to prevent it being activated.
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Old 21st May 2024, 23:57
  #113 (permalink)  
 
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I’ve been across the BoB more times than I care to remember over the last 15+ years and light chop to moderate turbulence in clear air isn’t unusual. It’s not jet stream country which would give the sort of CAT needed to cause an incident like this. After ten hours of fuel burn, coffin corner wouldn’t be too narrow.

Unfortunately, PIREPS aren’t a big thing in this part of the world unlike the USA where MET service are actively asking for them.

I’m leaning towards an unexpected weather encounter with a dry system which doesn’t show up very well on the radar due to a lack of water to reflect. A thunderstorm will give a strong indication and is easier to see and avoid. Interpreting weather radar displays involves more than just staying out of the red. I’ve been in green areas bouncing around and red areas where it’s been dead smooth. Cumulus cloud has strong air currents but gives little indication as it’s a dry cloud whereas nimbo stratus is stable but gives a strong radar signature due to its high water content. Before anyone comments on flying through the red, it was low down close to the airport and I was trying to avoid it. Another aircraft ahead of me was in the middle of it and advised that conditions were smooth.
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Old 22nd May 2024, 01:15
  #114 (permalink)  
 
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Originally Posted by AirScotia
FR24 data suggests SQ321 climbed from FL370 before the 'drop'. On passenger described a sudden nose-up climb. Could the flight crew have tried to get above weather at the last moment, but left it too late?
Autopilot disconnect followed by pitch up then stalled
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Old 22nd May 2024, 02:45
  #115 (permalink)  
 
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Originally Posted by B772
Autopilot disconnect followed by pitch up then stalled
Is that an informed rumor or speculation?
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Old 22nd May 2024, 03:13
  #116 (permalink)  
 
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Stall might get to zero G, but those people and the loose equipment were slammed into the overhead. It might not take much, like -1G in the plane frame of reference for 0.8 seconds to slam them up soon followed by a slam down. The plane would be dropping at 2G; over that time it would only move down 16 feet. Other values are possible, but the damage to the people and the interior seems in keeping with a -1G start. If it hit rising air after the downdraft, it could get to multiple Gs, which would slam the occupants down (slam the airplane up) severely.

I think I've done the calcs correctly.

Edit: There is the other possibility as well - hitting an updraft that initially accelerates the plane up, forcing people to their seats and then leaving the updraft with excess vertical speed to produce a negative acceleration on the plane with the people inside continuing up as Newton suggests until they encounter the overhead confines. Same effect in the aircraft frame of reference, slightly different data going into the Flight Data Recorder.

Last edited by MechEngr; 22nd May 2024 at 03:54.
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Old 22nd May 2024, 03:29
  #117 (permalink)  
 
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Question - at cruise speed and altitude - can CAT alone be strong enough to induce an immediate aerodynamic stall before pilots can react?
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Old 22nd May 2024, 03:42
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Originally Posted by tartare
Question - at cruise speed and altitude - can CAT alone be strong enough to induce an immediate aerodynamic stall before pilots can react?
This is a bit like asking "If there is a bit of string, is it long enough to tie my shoelaces?"
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Old 22nd May 2024, 04:06
  #119 (permalink)  
 
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Originally Posted by kit344
Surely there is a simple electronic solution with 2 very simple sensors.

If the seat is occupied, is the belt fastened ?

This would only need a couple of sensors, plus the additional wiring, logic and associated display(s).

Is this already implemented on some aircraft ?
Add a wee bit of logic; if any seat occupied and if that belt not fastened then shutdown engines.
what could go wrong?
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Old 22nd May 2024, 04:18
  #120 (permalink)  
 
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So many planes have seat-back displays (cannot tell if this is increasing or decreasing in number) but for those planes that have them, route a video to the screen in front of the unbelted passenger that shows what happens when the plane hits turbulence; put it on a loop marked by "PUT ON THE SEAT BELT NOW!"

The main problem is that in comparison with cars, the latch is backwards. At least all the planes I've ever been on have the slack adjustment at the latch while cars with seat-belt-use detectors have the tongue as the moving item. This means the switch to detect the tongue is installed in the latch is protected by the latch and has a fixed location at the end of the anchor cable, which allows routing the wire. On planes somehow the signal would have to get to the latch anywhere it is along the belt, leaving the electrical path exposed. Occupancy is easier to detect - short range time-of-flight sensors could be built into the seatback as part of the screen and see that the distance is less than to the seat back and keeps changing (fewer false positives from luggage.)

The only alternative is to use lithium powered transmitters in the latch similar to what is used in tire pressure monitors on cars. They don't need to signal very often; the pickup can be in the seatback display system, so range isn't a problem, but whoo-boy, 200-400 lithium cells? Not rechargeable and haven't been a problem in cars - never heard of one spontaneously going off and no different from the cells in non-smart wristwatches. Still it would take someone plucky to design that system and get it approved by the regulators, along with making it so that it did not interfere with the primary function of a latch that was probably perfected in 1940.
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