LATAM upset SYD-AKL Mon 11 Mar
Passengers aboard the LATAM flight said the Boeing 787 Dreamliner plunged earthward while flying from Sydney to Auckland on Monday evening, slinging unrestrained travellers out of their seats and smashing them into the roof of the cabin.
The Chilean airline said Tuesday it was working with authorities to unravel the unspecified "technical event", the latest in a string of safety incidents to plague US airplane manufacturer Boeing.
for goodness sake HOW LONG does it take to say that the seat moved ?
thereby dispelling worrying rumours of total gen failure ,screens going black etc!
it was said earlier that ‘it isn’t done that way’ and obviously a thorough investigation is vital but common sense says that a short interim statement would be in everyone’s interest!
PS looking at the seat fully forward position would it not be possible for the pilot to ‘spread his knees wide ‘ so that he would not hit the CC ? Would he have time ? How fast does the seat move ? Or was he getting in or out?
The Chilean airline said Tuesday it was working with authorities to unravel the unspecified "technical event", the latest in a string of safety incidents to plague US airplane manufacturer Boeing.
for goodness sake HOW LONG does it take to say that the seat moved ?
thereby dispelling worrying rumours of total gen failure ,screens going black etc!
it was said earlier that ‘it isn’t done that way’ and obviously a thorough investigation is vital but common sense says that a short interim statement would be in everyone’s interest!
PS looking at the seat fully forward position would it not be possible for the pilot to ‘spread his knees wide ‘ so that he would not hit the CC ? Would he have time ? How fast does the seat move ? Or was he getting in or out?
Last edited by mahogany bob; 17th Mar 2024 at 10:25.
Boeing and Flight Deck seat supplier, Ipeco, advise the 787 fleet of a known condition related to a loose/detached rocker switch cap on the fore/aft auxiliary rocker switch. This rocker switch is located on the seat back of both Captain and First Officer seats. Closing the spring-loaded seat back switch guard onto a loose/detached rocker switch cap can potentially jam the rocker switch, resulting in unintended seat movement.
Unintended fore/aft seat movement (due to a jammed seat back rocker switch) can be stopped with the emergency power cutoff switch, or by holding depressed the fore/aft rocker switch located on the inboard side of the seat pan in the direction opposite to the seat movement, or by holding depressed the manual fore/aft control lever on the inboard side of the seat pan to declutch the horizontal actuator. Please note that inputting an opposing fore/aft switch command will stop powered movement only for the duration that the seat software sees opposing commands. As soon as one of the fore/aft switches is released, the seat will resume movement following the remaining command. The preferred option is to shut off power using the power cut-off switch, but if the occupant is not able to reach that switch, the other options will halt the seat powered movement until power can be shut off. Boeing is evaluating potential updates to the appropriate Flight Crew Manual.
Unintended fore/aft seat movement (due to a jammed seat back rocker switch) can be stopped with the emergency power cutoff switch, or by holding depressed the fore/aft rocker switch located on the inboard side of the seat pan in the direction opposite to the seat movement, or by holding depressed the manual fore/aft control lever on the inboard side of the seat pan to declutch the horizontal actuator. Please note that inputting an opposing fore/aft switch command will stop powered movement only for the duration that the seat software sees opposing commands. As soon as one of the fore/aft switches is released, the seat will resume movement following the remaining command. The preferred option is to shut off power using the power cut-off switch, but if the occupant is not able to reach that switch, the other options will halt the seat powered movement until power can be shut off. Boeing is evaluating potential updates to the appropriate Flight Crew Manual.
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O.k. So it is possible to at least stop the motion. However since the seat movement control seem to go over software, why did they not put in some safety mechanism for a stuck switch. Stuck switch is a typical scenario for any functional safety analysis. Continuous forward movement until the forward mechanical stop of the seat should be looked as a dangerous situation. Now with 20/20 hindsight.
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Disconnect and reconnect power at least once every 120 days, but maybe it should be every 25 days.
It's as if the writing of and functioning of software in aircraft systems isn't the subject of standards. If only software engineers could anticipate the remote possibility that the software they design will be running continuously in hardware that doesn't take a coffee break.
It's as if the writing of and functioning of software in aircraft systems isn't the subject of standards. If only software engineers could anticipate the remote possibility that the software they design will be running continuously in hardware that doesn't take a coffee break.
There is another aspect that rarely seems to get fairly assessed: In my experience, Power-up Cold Start BIT is often when the most rigorous on-aircraft LRU (Line Replaceable Unit) testing can be done (often while outputs are isolated). It strikes me as sensible that this should be run at intervals, at a convenient time (with the aircraft parked), in order to establish the integrity of the LRUs, rather than just relying on the continued apparent good performance of the bits of a system that remain running indefinitely, although if designed well, that should also offer high degrees of assurance about the LRU system integrity, but that cannot cover all cases. For example, during Cold Start BIT, one may check the internal 28V Power Supply hold up capacitance, something which may not be possible at other times, but may be important to confirm that the LRU can still meet the power-interrupt play-through period. Besides, a lot of work goes into developing Power-up Cold Start BIT, so it is heartening for the software engineers, etc., etc., to know that it is being exercised more often than once in a blue moon.
From a crew perspective, any time there is a maximum system reset interval, I hope that either the system makes it clear that that event horizon is approaching, in a suitable timely manner, or that the crew are able to independently conform that the maintenance action has been carried out in the recent past. I hate being asked to trust that something on which lives may depend has been done, but in some circumstances, that is what we have to do.
Just food for thought...
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O.k. So it is possible to at least stop the motion. However since the seat movement control seem to go over software, why did they not put in some safety mechanism for a stuck switch. Stuck switch is a typical scenario for any functional safety analysis. Continuous forward movement until the forward mechanical stop of the seat should be looked as a dangerous situation. Now with 20/20 hindsight.
The clear problem isn't the simply the switch, but that there apparently was an added obstruction, the meal tray, that was trapped. Can't tilt down - pilots thighs are in the way. Can't go right or left because of surrounding structure. And can't go up if it's under the wheel and maybe a bit of belly fat or seat-belt buckle (no photos, but perhaps a pilot might clarify) . The seats don't move lightening fast, and it may be the pilot even started out having to suck in a bit while tucking under the wheel, which would have been fine but doesn't leave an exit strategy if a flight attendant then directly or indirectly pushes the go forward button.
Look at the typical analysis - the switch jams and the seat moves. If it moves forward it cannot reach the control column. The pilots legs are supposed to be on either side of the control column, so they cannot be forced against it. The edge of the seat should be ahead of the pilot's abdomen, unless the pilot is morbidly obese; I haven't see all pilots but I think I would have noticed, but that is covered in the human factors books for 5th and 95th percentile design guidance, so any body outside those limits would be unlikely to be considered. Sure, it's uncomfortable getting pushed up with the knees folded, but without cockpit dimensions and the human factors limits, I can't be sure it would be "unsafe."
One could suppose a second switch in series with the first that applies power and the rocker switch controls direction. Seems good, but then there are two mechanical places for the seat to fail to operate. Likewise is one switch can override the other and one fails then the seat is also unable to move.
Frankly, I'm not a fan of power seats, but then I've read on a number of cases where a mechanical lever gets stuck and when the pilot get to Vr, pulls back, nose comes up, and the seat comes loose and takes the pilot away from the controls,.
If it's the meal tray - the fix is really simple. Get new trays so that this cannot happen.
I also really, really, really want to see a photo of the switch that is being blamed. I worked with military equipment for 30 years and the rule was, if they could break it they would break it. We put equipment into HMMWVs, Bradleys, M113s, and Striker vehicles - people with big feet, big boots, swinging guns around. Did not have a problem with broken switches. Mostly because they had switch guards, similar to ones I see in cockpit photos. Does this rocker not have a switch guard?
On Mar 15th 2024 Boeing released a message to operators of all Boeing 787 variants referencing another message sent out in 2017 advising operators to apply adhesives to the rocker (pilot seat movement) switch caps to prevent them from coming loose.
I also really, really, really want to see a photo of the switch that is being blamed. I worked with military equipment for 30 years and the rule was, if they could break it they would break it. We put equipment into HMMWVs, Bradleys, M113s, and Striker vehicles - people with big feet, big boots, swinging guns around. Did not have a problem with broken switches. Mostly because they had switch guards, similar to ones I see in cockpit photos. Does this rocker not have a switch guard?
Too Long Didn't Watch version is that there is a cover to protect the rocker switch on the seat back but if the rocker switch and cover are in poor condition the seat can move just from leaning or pressing on the cover.
A question for the B787 drivers, or anyone else with relevant knowledge: Does the rocker switch on the seat back drive the seat at the same speed as the switch on the seat pan, or is the speed a bit faster given that it's intended to be used when the seat is unoccupied?
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The primary problem is the switch. How necessary is the switch, since I believe no other aircraft type has it? If it's necessary for the 787, replace it with a more robust switch. That would be the seat supplier's responsibility, wouldn't it?
The secondary problem would seem to be what looks like an awkward location of the power cutoff switch, as if nobody anticipated any emergency use. Maybe it would have been easier for the steward behind the seat to operate the switch.
Redesigning the tray should be lhe last consideration, shouldn't it?
The seat seems to take a total of about ten seconds to go from fully backward and outward position to fully forward positon; five seconds to move inward then five seconds to move forward.
It looks to me that, when the seat is in the forward position, there is no room for the tray to go under the control wheel so that is what it would come in contact with.
The secondary problem would seem to be what looks like an awkward location of the power cutoff switch, as if nobody anticipated any emergency use. Maybe it would have been easier for the steward behind the seat to operate the switch.
Redesigning the tray should be lhe last consideration, shouldn't it?
The seat seems to take a total of about ten seconds to go from fully backward and outward position to fully forward positon; five seconds to move inward then five seconds to move forward.
It looks to me that, when the seat is in the forward position, there is no room for the tray to go under the control wheel so that is what it would come in contact with.
The tray can be addressed in days or eliminated entirely. Software or an electrical fix is months or more. The tray takes no regulator approvals, except airline management.
Now you don't think it was something simple and silly, like ... someone leans on seat motion switch, seat moves, pilot (instinctively) grabs control wheel, autopilot lets go, shake-and-wobble (screams from pax).
It will all come out in the wash.
It will all come out in the wash.
What is ironic ,if the seat scenario is correct, is that when Boeing designed the 777 and the 787 they were insistent on the control yoke being of traditional design even though the aircraft was FBW. So now there is a possible situation where that very same control column which was supposed to make pilots feel like real pilots, has metaphorically kicked the Captain in the goolies. If they had been fitted with side-sticks ( a US response to the benefits of FBW) and a fold out table then all those passengers would have arrived safely in Chile. Instead a dodgy seat and a refusal to move with the technology has possibly led to this incident. And before the mob with their pitchforks start shouting "What about the Voyager, what about the Voyager?" that was a pilot's lack of camera SA that caused that, not some cheap and nasty seat switches.
What is ironic ,if the seat scenario is correct, is that when Boeing designed the 777 and the 787 they were insistent on the control yoke being of traditional design even though the aircraft was FBW. So now there is a possible situation where that very same control column which was supposed to make pilots feel like real pilots, has metaphorically kicked the Captain in the goolies. If they had been fitted with side-sticks ( a US response to the benefits of FBW) and a fold out table then all those passengers would have arrived safely in Chile. Instead a dodgy seat and a refusal to move with the technology has possibly led to this incident. And before the mob with their pitchforks start shouting "What about the Voyager, what about the Voyager?" that was a pilot's lack of camera SA that caused that, not some cheap and nasty seat switches.
That switch in the seat backrest will be used at least every cycle, so in the 5 digit range. There must be a safety analysis for a stuck switch or damaged cable yielding seat forward motion.
There was a reason in the 747 to have 2 switches in series, so with what rationale now a single switch does the same job?
There was a reason in the 747 to have 2 switches in series, so with what rationale now a single switch does the same job?
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