Severe turbulence LHR-SIN. One dead.
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With modern weather radars I think it makes this scenario even more likely. The number of times I have had the weather picture change the closer we got to the buildup has left me with the idea that technology has taken a backward step. They seem to present the wx on a need to know basis and it doesn't think you need to know until it can be too late.
With modern weather radars I think it makes this scenario even more likely. The number of times I have had the weather picture change the closer we got to the buildup has left me with the idea that technology has taken a backward step. They seem to present the wx on a need to know basis and it doesn't think you need to know until it can be too late.
While such a rapid descent may be within limits to you guys up front, it's certainly NOT seen as normal to anyone on the other side of the closed door, whether they be crew or paying passengers. I feel that some on here need to be reminded of that, and if it was a deliberate descent, a quick warning wouldn't have gone amiss. Given the apparent damage in the cabin, it doesn't seem that NORMAL to me.
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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.
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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You can't stall a 777 - a FBW aircraft - while flying VNAV at FL370. You need to override two systems and get to Direct Law OPS. Also, during severe turbulence you may have to disconnet A/Ts to avoid excessive thrust input from the FBW computer. While nothing can be ruled out, a stall at this stage of flight would be a first in 31 years of 777 OPS. What could happen is, if the 777 (not the 737, not the 747 these are different aircraft) is in the upper levels of its maximum operating ceiling - which appears it was not but let's wait for the FDR data - then you might get a stick shaker due to turbulence. But 99.99% it was not a stall, in my professional opinion. Let's wait and see what the Voice Recorder transcripts show. Just wait... it could be interesting.
Just how many videos have I witnessed over the last 10 years or so from PPL's to Senior BA Captains claiming "turbulence is uncomfortable, but never dangerous?"
I cringe when I see such.
Aircraft (although rare) have been ripped apart in turbulence. This story shows that you can never take anything for granted? You just do not know?
Pax... always keep your belt fastened, as tight as is comfortable.
Pilots... don't needlessly sit in turbulence, find smoother air.
I experienced nearly 4 decades in aviation and always found a way out of unpleasant conditions. Not always 100% for sure but I do remember being tossed around like crazy in a GV at FL450 so went down in increments to FL350 to find something acceptable. Pax were very very grateful, I had one less thing to worry about, FA could continue working and we all arrived safely. Operator picked up the extra fuel bill... so what?
I cringe when I see such.
Aircraft (although rare) have been ripped apart in turbulence. This story shows that you can never take anything for granted? You just do not know?
Pax... always keep your belt fastened, as tight as is comfortable.
Pilots... don't needlessly sit in turbulence, find smoother air.
I experienced nearly 4 decades in aviation and always found a way out of unpleasant conditions. Not always 100% for sure but I do remember being tossed around like crazy in a GV at FL450 so went down in increments to FL350 to find something acceptable. Pax were very very grateful, I had one less thing to worry about, FA could continue working and we all arrived safely. Operator picked up the extra fuel bill... so what?
Yes as well all have, sometimes it’s just not possible to avoid
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Hello, inquisitive frequent but nervous flyer here. I didn’t used to be a nervous flyer, but that changed following an experience flying beteeen Malè and Dubai on the way back from my honeymoon in 2012, on an Emirates 777.
It began with what I would describe as the worst persistent turbulent I have ever experienced. Violent up and down motion coupled with the occasional lurch right or left. Passengers were screaming, one or two crying, and the bit that got me was the cabin crew strapping themselves in to the nearest available seat and looking deeply uncomfortable, despite their best efforts to put on a brave face.
This lasted for maybe 15 - 20 minutes, but more than long enough for my liking, before things smoothed out to a steady cruise. I waited a good 15 minutes or so to ensure things had calmed down, waited for the seatbelt sign to go off, and went to use the toilet (as my breakfast was making a concerted effort to reappear).
There was a queue to use the toilet, so I stood somewhere in the galley. Precisely what happened next is slightly sketchy in my mind, but I found myself flung into the ceiling of the plain and feeling “stuck” there for a split second, before being thrown back to the floor (accompanied by part the ceiling panel I had been thrust into), with some more lurching then throwing the food trolley on top of me, pinning me to the ground. I hadn’t appreciated how heavy these things were.
The cabin crew quickly pulled the trolley off me, checked I was ok, apologised and sent me back to my seat. I had a few cuts and bruises, and though I didn’t realise it at the time, I think a broken rib where the trolley had landed on me.
I remember asking the crew after landing, “how common is that sort of thing?”, and was told “not common at all”. To my knowledge this particular event didn’t make the news as there were no injuries requiring medical treatment (I think I was as badly hurt as anyone, and I was “ok” physically).
I’ve certainly never experienced anything remotely close to this on hundreds of flights before or since (though I do no get very uneasy at the slightest bit of turbulence), so this incident got me thinking: just how rare is such a terrible experience involving turbulence, that people find themselves hitting the ceiling etc.?
Beyond my obvious sympathy for the man who died on the plane and his family, I feel for those who now have face more long flights just to get home. I saw an interview with one man who was having to abandon his attempt to get to his son’s wedding as getting there and back would now require another 5 flights, something he just couldn’t stomach. I still had another 7 hour flight to Manchester to look forward to after my own experience, and I didn’t enjoy it one bit (smooth though it was in actual fact).
My heart goes out to all those affected by this.
It began with what I would describe as the worst persistent turbulent I have ever experienced. Violent up and down motion coupled with the occasional lurch right or left. Passengers were screaming, one or two crying, and the bit that got me was the cabin crew strapping themselves in to the nearest available seat and looking deeply uncomfortable, despite their best efforts to put on a brave face.
This lasted for maybe 15 - 20 minutes, but more than long enough for my liking, before things smoothed out to a steady cruise. I waited a good 15 minutes or so to ensure things had calmed down, waited for the seatbelt sign to go off, and went to use the toilet (as my breakfast was making a concerted effort to reappear).
There was a queue to use the toilet, so I stood somewhere in the galley. Precisely what happened next is slightly sketchy in my mind, but I found myself flung into the ceiling of the plain and feeling “stuck” there for a split second, before being thrown back to the floor (accompanied by part the ceiling panel I had been thrust into), with some more lurching then throwing the food trolley on top of me, pinning me to the ground. I hadn’t appreciated how heavy these things were.
The cabin crew quickly pulled the trolley off me, checked I was ok, apologised and sent me back to my seat. I had a few cuts and bruises, and though I didn’t realise it at the time, I think a broken rib where the trolley had landed on me.
I remember asking the crew after landing, “how common is that sort of thing?”, and was told “not common at all”. To my knowledge this particular event didn’t make the news as there were no injuries requiring medical treatment (I think I was as badly hurt as anyone, and I was “ok” physically).
I’ve certainly never experienced anything remotely close to this on hundreds of flights before or since (though I do no get very uneasy at the slightest bit of turbulence), so this incident got me thinking: just how rare is such a terrible experience involving turbulence, that people find themselves hitting the ceiling etc.?
Beyond my obvious sympathy for the man who died on the plane and his family, I feel for those who now have face more long flights just to get home. I saw an interview with one man who was having to abandon his attempt to get to his son’s wedding as getting there and back would now require another 5 flights, something he just couldn’t stomach. I still had another 7 hour flight to Manchester to look forward to after my own experience, and I didn’t enjoy it one bit (smooth though it was in actual fact).
My heart goes out to all those affected by this.
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Flew that route for many years. We called it 'thunderstorm alley'. Agree entirely with 'Lookleft' never trusted those new 'Auto tilt' functions, always had a look around in manual. Surprising how a dry cell could pop up out of nowhere. Also turn the lights down and have a peek out the window for those big black lumpy bits blocking out the stars.
I sense they ran into a CB, why is the big question.
I sense they ran into a CB, why is the big question.
Humble SLF here but a long standing long haul PAX and I have also flown through that and other areas of the convergence zones around the planet. Indeed in that very area a long time ago in a 707 we turned back to India!
As for experience of CAT I was a young boy on another Air France 707 which hit CAT over US. CC and drinks carts became airborne and indeed landed on other PAX. Unbelievably we continued to Paris and were met by a fleet of ambulances. It was my last flight with that carrier.
I always travel with belt on but must admit to going for a stretch in galley or bar if on EK as well as the obvious toilet breaks but I don’t think turbulence has got any worse over the years there are just certain areas of the planet like this where it is more common.
However I have noted that when crossing behind a 380 even several miles behind and below you can get a bit of a jolt.
Cheers
Mr Mac
For the sake of rumours, as long as we dont have any report for a year or two - I have a direct question on this 1-min anomaly (thanks for the ADS-B graphs, Bleve). If in VNAV mode or ALT HOLD, would you ever expect (or have experienced) a deviation of up to 400 feet from the bugged FL? For me the +400ft deviation from a bugged F370 indicates to either A/P disconnect or A/P operation in very unusual regime (cant cope with the turbulent rich updraft of the century for at leat 30 seconds).
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For the sake of rumours, as long as we dont have any report for a year or two - I have a direct question on this 1-min anomaly (thanks for the ADS-B graphs, Bleve). If in VNAV mode or ALT HOLD, would you ever expect (or have experienced) a deviation of up to 400 feet from the bugged FL? For me the +400ft deviation from a bugged F370 indicates to either A/P disconnect or A/P operation in very unusual regime (cant cope with the turbulent rich updraft of the century for at leat 30 seconds).
I don't like to criticize other pilots' actions (that's easy when you're not there). But if someone said to me just tell us the one thing you think might have happened I would say, with extreme caution, that the descent was initiated by the pilots voluntarily by switching from VNAV to V/S mode.
I don't know and don't want to speculate further as to what - if it is valid based on data online... a big if - what might have caused the +400 feet course.
I was going to speculate further on a possible reason for this speculated +400 feet variation but I won't after all, because the VCR (and crew interviews - the NTSB are in their way) will answer this emphatically.
I personally doubt there was AP Disconnect at any stage of the flight. But this is a personal opinion.
Having only used the turbulence mode twice in six years on the DC 10, my only comment is what it does and why;
disengages autopilot, auto throttle and auto trim ..flight director goes to a preset cruise attitude but control wheel steering remains engaged..that is IIRC.
One sets cruise power and pole the flight director attitude which leaves the aircraft rising and descending with the vertical currents.
This ensures that the aircraft stays flying at roughly the correct speed and that the pilot doesn’t over stress the aircraft.
As one knows the vertical currents are extreme and the worst turbulence is where they reverse direction I.E where one leaves the rising core into the descending (and precipitating) zone.
disengages autopilot, auto throttle and auto trim ..flight director goes to a preset cruise attitude but control wheel steering remains engaged..that is IIRC.
One sets cruise power and pole the flight director attitude which leaves the aircraft rising and descending with the vertical currents.
This ensures that the aircraft stays flying at roughly the correct speed and that the pilot doesn’t over stress the aircraft.
As one knows the vertical currents are extreme and the worst turbulence is where they reverse direction I.E where one leaves the rising core into the descending (and precipitating) zone.
Only half a speed-brake
Joining late and not really reading the previous pages due to chatting exhaustion on the topic elsewhere,
but a bit surprised about the wide variety of opinions still prevailing. It's loose bits of ideas coming to my mind, reader's patience appreciated, but I think the below frames a coherent picture.
The T7 is how much, an 160t aeroplane at this stage?While CAT is a thing and joining jetstream could be ugly, I don't subscribe to the rogue wave equivalent of a magnitude which throws a longhauler around while all traffic before and after sailed through unscathed.
Meaning to say, a concentrated whirlwinds out of the blue which do exist don't really have the energy to lift 160ish t 400 feet upwards against the controls of the AP. But a CB would, or the THS+2xGE90s getting mishandled, agreed?
About wake turbulence - sure, nasty as can be however for that I'd expect a roll-and-sink type of sequence not a climb of 500 FPM for 60ish seconds almost. But agree the transmitted data is too granular for any hard conclusions.
Most LOC-I seem to have an initial disturbance further excabarated by non optimal crew input only which then compounds into the undesirable aircraft state.
Evidenced by the repeated hailstrike events worldwide, flying into TSCB is still a thing. As we speak there are screen overlays from FR24 and alike floating in the soc media space, showing the SIA ship being the only one not detouring at the time space of the occurnce.
Occam would have it: The plane may have bumped a TS which threw it upwards possibly losing speed, engines spooling up compounding the pitch up effect and increasing the climb. During the pushover commanded or not, perhaps even pre-stalled, negative G developed sending liveware and carts to the ceiling and opening the PSU before all came crashing down causing more havoc and the heavy injuries as bodies get slammed over the armrests.
Be it the case here or not, that has happened before many times again and again. NB the incentives from all stakeholders to label any such encounter as CAT/vis major are rather loaded.
Which might the novelty here. The airline being fully exposed to the blast of responsibility should it transpire and be confirmed the shop keeping had been sub-proficient.
Unrelated to the above, I loathe the newest auto scanning WXR and my colleagues experience reads the same in their faces. The original auto-tilt was quite OK but still MAN needed to disect a nasty area. Of which the recently trained colleagues have no experience. Sadly for all.
Stay safe everyone.
but a bit surprised about the wide variety of opinions still prevailing. It's loose bits of ideas coming to my mind, reader's patience appreciated, but I think the below frames a coherent picture.
The T7 is how much, an 160t aeroplane at this stage?While CAT is a thing and joining jetstream could be ugly, I don't subscribe to the rogue wave equivalent of a magnitude which throws a longhauler around while all traffic before and after sailed through unscathed.
Meaning to say, a concentrated whirlwinds out of the blue which do exist don't really have the energy to lift 160ish t 400 feet upwards against the controls of the AP. But a CB would, or the THS+2xGE90s getting mishandled, agreed?
About wake turbulence - sure, nasty as can be however for that I'd expect a roll-and-sink type of sequence not a climb of 500 FPM for 60ish seconds almost. But agree the transmitted data is too granular for any hard conclusions.
Most LOC-I seem to have an initial disturbance further excabarated by non optimal crew input only which then compounds into the undesirable aircraft state.
Evidenced by the repeated hailstrike events worldwide, flying into TSCB is still a thing. As we speak there are screen overlays from FR24 and alike floating in the soc media space, showing the SIA ship being the only one not detouring at the time space of the occurnce.
Occam would have it: The plane may have bumped a TS which threw it upwards possibly losing speed, engines spooling up compounding the pitch up effect and increasing the climb. During the pushover commanded or not, perhaps even pre-stalled, negative G developed sending liveware and carts to the ceiling and opening the PSU before all came crashing down causing more havoc and the heavy injuries as bodies get slammed over the armrests.
Be it the case here or not, that has happened before many times again and again. NB the incentives from all stakeholders to label any such encounter as CAT/vis major are rather loaded.
Which might the novelty here. The airline being fully exposed to the blast of responsibility should it transpire and be confirmed the shop keeping had been sub-proficient.
Unrelated to the above, I loathe the newest auto scanning WXR and my colleagues experience reads the same in their faces. The original auto-tilt was quite OK but still MAN needed to disect a nasty area. Of which the recently trained colleagues have no experience. Sadly for all.
Stay safe everyone.
Zero g means no lift, which means it is basically impossible to stall. Stall at cruise would require an increase angle of attack, which increases the lift and thus the load factor (lift over weight).
Aircraft stability also plays a role. When the airplane gets into a downdraft this will instantaneously decrease the angle of attack which will make the aircraft want to pitch up while it starts to accelerate down. When entering an updraft, the angle of attack will increase, making the plane want to push the nose down. This will make the effect in the back worse than in the front.
Aircraft stability also plays a role. When the airplane gets into a downdraft this will instantaneously decrease the angle of attack which will make the aircraft want to pitch up while it starts to accelerate down. When entering an updraft, the angle of attack will increase, making the plane want to push the nose down. This will make the effect in the back worse than in the front.
Thanks for the answers. I was indeed interested in the system design / system behaviour aspect. If I pointed to possible A/P disconnect it was also rather more to automatic disconnect reasons by the system itself. Bad air data or otherwise unhappy.
In relation to the age old seatbelt issue.
I am sure many of you will have seen or heard of the latest social media nonsense about seatbelts on aircraft. The "influencers" who sit with their knees up under their chin and the seatbelt fastened around their ankles. Then you have the "I want to sleep reclined and I can't get comfy with the seatbelt on" types.
Aircrew can tell, advise, demand pax to use their seatbelts til they are blue in the face but you are always going to have those who refuse to do so. Apart from kicking them off the aircraft, there is little that can be done about it.
There is a pax who was aboard this flight who has gone to the media with her story and she makes no bones about not wearing her seatbelt from the moment the lights go off after takeoff til the aircraft is decending on approach and she is determined not to change her behaviour despite ending up slamming the overhead locker with her face.
Some elements of humanity simply will never comply. And there is nothing anyone can do about that.
This incident was an absolute tragedy and as much as the media love to speculate and sometimes blame something or someone before the investigators pick up their clipboards. It along with the seatbelts is a small part of the section of humanity that lives to exasperate.
Hopefully as the days and weeks go by there can be a clear reason as to why this flight was so badly and tragically affected, but at the same time there is no cure for turbulence nor those who refuse to comply with the basic safety measures in place.
I am sure many of you will have seen or heard of the latest social media nonsense about seatbelts on aircraft. The "influencers" who sit with their knees up under their chin and the seatbelt fastened around their ankles. Then you have the "I want to sleep reclined and I can't get comfy with the seatbelt on" types.
Aircrew can tell, advise, demand pax to use their seatbelts til they are blue in the face but you are always going to have those who refuse to do so. Apart from kicking them off the aircraft, there is little that can be done about it.
There is a pax who was aboard this flight who has gone to the media with her story and she makes no bones about not wearing her seatbelt from the moment the lights go off after takeoff til the aircraft is decending on approach and she is determined not to change her behaviour despite ending up slamming the overhead locker with her face.
Some elements of humanity simply will never comply. And there is nothing anyone can do about that.
This incident was an absolute tragedy and as much as the media love to speculate and sometimes blame something or someone before the investigators pick up their clipboards. It along with the seatbelts is a small part of the section of humanity that lives to exasperate.
Hopefully as the days and weeks go by there can be a clear reason as to why this flight was so badly and tragically affected, but at the same time there is no cure for turbulence nor those who refuse to comply with the basic safety measures in place.
Flight Detent #155 
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Air-mass first - aircraft mass (accelerations), then aerodynamics (attitudes), and belatedly human input (controls). Where the latter are often reactions to what is normally expected opposed to the reality of the abnormal air-mass.
Surprise, yes, an unexpected event.
Fundamental surprise, yes; an unimaginable situation with respect to experience and training ("this cannot be happening", 'aircraft do not react like this', heave, sway, yaw, pitch, roll, speed, vibration, noise).
---
In addition to the usual caveats on the interpretation and use of downlinked data, incidents such as this challenge the perceived point of reference.
In smooth air, air-data might be equated to aircraft motion with respect to the airmass.
However, in very turbulent air, it is more likely that a change in sensed air-data at a given time represents the motion of the airmass; the aircraft subsequently reacts relative to the airmass.
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Air-mass first - aircraft mass (accelerations), then aerodynamics (attitudes), and belatedly human input (controls). Where the latter are often reactions to what is normally expected opposed to the reality of the abnormal air-mass.
Surprise, yes, an unexpected event.
Fundamental surprise, yes; an unimaginable situation with respect to experience and training ("this cannot be happening", 'aircraft do not react like this', heave, sway, yaw, pitch, roll, speed, vibration, noise).
---
In addition to the usual caveats on the interpretation and use of downlinked data, incidents such as this challenge the perceived point of reference.
In smooth air, air-data might be equated to aircraft motion with respect to the airmass.
However, in very turbulent air, it is more likely that a change in sensed air-data at a given time represents the motion of the airmass; the aircraft subsequently reacts relative to the airmass.
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Andy_S
That's not what I said..... I see your profile has you as an engineer..... An aircraft engineer? Or a gas-fitter?
Following a severe turbulence report there is always a conversation between engineers and pilots to ascertain EXACTLY what degree of turbulence was encountered. In fact, most companies have a source of reference compliant with both Airbus and Boeing advice, that precisely defines the difference between moderate and severe turbulence. The reason being, is that severe turbulence engineering checks can take an aircraft out of service for several days and occupy multiple tradesmen who should be working on other tasks. Hence that call is rather important commercially for the airline. I have had several incidents of 'Severe Turbulence' in my career. None of them warranted an immediate diversion although the aircraft was grounded for checks on reaching the company's preferred engineering destination.
From what I have heard described here and elsewhere, this encounter was beyond severe and there will be a high likelyhood of significant airframe overstress. Now..... I was not teh Captain in that left-hand seat so I cannot judge the conditions for myself. However, until I see evidence to the contrary I would entirely support the Captain's decision to immediately divert to BKK.
Following a severe turbulence report there is always a conversation between engineers and pilots to ascertain EXACTLY what degree of turbulence was encountered. In fact, most companies have a source of reference compliant with both Airbus and Boeing advice, that precisely defines the difference between moderate and severe turbulence. The reason being, is that severe turbulence engineering checks can take an aircraft out of service for several days and occupy multiple tradesmen who should be working on other tasks. Hence that call is rather important commercially for the airline. I have had several incidents of 'Severe Turbulence' in my career. None of them warranted an immediate diversion although the aircraft was grounded for checks on reaching the company's preferred engineering destination.
From what I have heard described here and elsewhere, this encounter was beyond severe and there will be a high likelyhood of significant airframe overstress. Now..... I was not teh Captain in that left-hand seat so I cannot judge the conditions for myself. However, until I see evidence to the contrary I would entirely support the Captain's decision to immediately divert to BKK.