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Serious incident to the 777-300ER on 5 April 2022 at CDG [pdf]
- the_mitsuhiko 3y agoA summary / quotes can be found here: https://avherald.com/h?article=4f700fec https://avherald.com/h?article=4f700fec
- epups 3y agoAn excerpt: > The captain then acted, most probably by reflex action, on the control column to reduce this pitch attitude without taking back the controls and making the procedure call-out, based on the principle of only one pilot having the controls. The two pilots then simultaneously made inputs on the controls. The pitch controls were desynchronized for 12 s due to opposing forces It sounds like Air France has still not trained their pilots on proper cockpit discipline. This already proved fatal before (AF 447).
- cm2187 3y agoEven without training, I don't see how the pilots could make this error, I am sure every pilot at Air France is very much aware of how AF447 happened. I am a bit puzzled how they managed to basically replicate it.
- Retric 3y agoDoing the right thing once is fairly easy, doing the right thing 100,000 times is vastly harder. The issue is the UI around dual inputs not lack of training or awareness.
- stef25 3y agoFriend of mine is a commercial airline pilot, she says it's like driving a bus nowadays.
- scrumper 3y agoPeople say this to downplay what flying an airliner is like, but driving a bus is hard! They're huge, have lots of inertia, you've got dozens of lives in your hands, some systems complexity, schedule pressure, a percentage of whacko passengers (and no crew to help) and that's on top of the day-to-day lunatics with whom you have to share the road. I'm sure your friend is being humble and is perhaps romanticizing the stick-and-rudder days; I still think it says more about how difficult it is to drive a bus rather than how easy it is to fly an airliner. As a passenger, the real problem with flying nowadays is that it's quite a lot like riding the bus.
- WatchDog 3y agoOne of the impressive things about flight 1549 is how quickly captain Sully declared “my aircraft” which was immediately acknowledged by copilot Skiles.
- cm2187 3y agoWell it seems that in this case the problem stopped immediatly after the captain said my aircraft. The problem if I understand the report is that before that he was applying inputs even though he wasn't supposed to fly.
- pimpampum 3y agoStill, why was it off course and at an unexpected angle? The captain reacted wrong, but what caused the reaction? There was another problem before.
- helsinkiandrew 3y ago> The two pilots then simultaneously made inputs on the controls for 53 s. The pitch controls were desynchronized for 12 s due to opposing forces. Does anyone know what "The pitch controls were desynchronized for 12s" actually means? and was this a system response to the two controls having opposing forces, or an unexpected result of it.
- eknkc 3y agoIt means one was trying to increase pitch angle (trying to climb?) and one was trying to do the exact opposite. They were canceling each other’s inputs.
- gambiting 3y agoit's an "interesting" difference between Airbus and Boeing - on Boeings the input is averaged between both pilots. So if one is giving it maximum tilt left, the other maximum tilt right, the airplane doesn't move. On an Airbus both sticks have to mave in unison, they are physically linked. Edit: Actually, I'm completely wrong, ignore me
- andruby 3y agoCould it be that you mean the opposite: Airbus is averaged, Boeing is physically linked? That is my understanding of both systems at least
- fhars 3y agoWasn't the problem here that Boeing is only linked if no great force is applied and also switches to the average it the force difference is large enough, and that it didn't really document that behaviour?
- masklinn 3y agoIIUC the possibility of breakout is documented, but pilots > often only associated it with a jammed control I assume in no small part because > the description of the system in the [flight crew operating manual] was limited to an explanation about the risk of a control jamming And it seems likely the precise behaviour of the system in case of breakout is not documented either.
- skylabmelody 3y agoI don't want to minimize pilot errors but I can't stop thinking this dual inputs system easily ranks in the top 5 of the worst design ideas in history. Probably just behind the MCAS.
- lbourdages 3y agoIs there really an alternative? Say one pilot loses consciousness, the other one has to extract them from their seat before they can fly the airplane. That's no easy task - humans are surprisingly heavy once they pass out.
- voxadam 3y agoThree pilots with a voting algo, obviously. Or, maybe, a supreme court of nine pilots all constantly and continuously in search of perfect aerodynamic justice. Ah hell, just let ChatGPT fly the damn plane. Edit: I've got it! We'll have a single pilot but they'll be based on a Rust rewrite of ChatGPT running on RISC-V.
- winchester6788 3y ago2 chatgpt instances controlling the dual inputs would be funny
- skylabmelody 3y agoBy "dual input system" I was referring to the fact that both pilots can apply input into their sticks or trim wheels simultaneously resulting into inputs cancelling each other out or de-synchronizing.
- lbourdages 3y agoAgreed, that seems like a really bad design. At the very least there should be an alert whenever the system detects that both pilots are touching the controls.
- masklinn 3y ago
- starfox64_ 3y ago> 4.2 Safety measures taken by the manufacturer I would have hoped for Boeing to add a warning system in the case of dual input, like in Airbus aircrafts, but it seems they did the bare minimum here. Simple warnings were added to the pilot hanbook that basically amount to "don't apply opposite inputs".
- juujian 3y agoIf Boeing was a student, they would be the kind that does the bare minimum in every class just so they don't fail.
- ramijames 3y agoThis seems to be the core reason why pure capitalism is a failed concept. There must be regulatory oversight to ensure that what is done MOST RIGHT and not CHEAPEST.
- stef25 3y agoThinking that "fuck it, we'll risk loss of human life and possibly having to shut down the company" isn't due to capitalism, it's psychopathy and I'm fairly sure that never happened. Anything that goes wrong is due to dysfunctional management, not greed.
- masklinn 3y agoFord literally did a cost/benefit analysis for fixing the Pinto versus societal costs of injuries and deaths, and went with the cheaper option. They actually put it to paper and sent that to the NHTSA to argue against fuel system regulations. “Dysfunctional management” is a direct function of managerial incentives, which is generally capitalistic greed (aka “obligation to maximize shareholder value”)
- nradov 3y agoEvery auto manufacturer does the same thing. The Ford Pinto case was particularly poorly handled. But for any given car design, it's always possible to further improve safety by making it more expensive. A Mercedes-Benz S-Class is far safer than a Nissan Sentra by any objective standard. Should we tighten safety requirements so that every car is as safe as the S-Class, and costs about as much? Where do we draw the line on safety regulations?
- K0balt 3y ago“…The documentation provided to the pilots did not therefore allow them to reasonably envisage that, in the event of antagonistic control inputs exceeding the breakout mechanism's activation threshold, the controls would be desynchronized and the control surface would react according to the mean control positions. The behaviour of the aeroplane during this phase of simultaneous control inputs could not be anticipated.” It is unconscionable that the training for this aircraft does not include a thorough examination of competence in interpreting multiple control inputs/control jamming. The fact that under these conditions the aircraft defaults to responding to -neither- control input, but rather the mean of the two, without any master caution or obvious alarm condition seems like a dubious engineering decision at best, and certainly should merit significant training to recognize the conditions under which the -aircraft would decide not to respond fully to ANY control input- . Of course, cockpit discipline is paramount, and this near-accident was a direct result of CRM failure, but by design the control system makes this forseeable eventuality much more insidiously dangerous and disorienting to pilots. At the very least, significant training on the specific possibility is merited, and an alarm condition for this specifically out of parameter situation should exist. If I didn’t know better, I would suspect that Boeing was intentionally engineering their flight control automation systems to exploit foreseeable pilot errors and exacerbate them, and then maliciously forgoing trading requirements on those features.
- masklinn 3y agoTBF the behaviour of averaging dual inputs is exactly what Airbus does as well.
- K0balt 3y agoHopefully that decision is based then on sound engineering and aviation principles. I can certainly see that as a “better than nothing “ approach, and I can imagine some failure scenarios where it might even be the -best- solution… but it would seem that that operating mode would at least merit enough training so that pilots would recognize the operating mode, as well as some kind of obvious indication that the airplane was electing to algorithmicly synthesize the control outputs. Wouldn’t it be better to simply hard-lock the controls together, with a release switch for each control to allow either pilot to unlock their controller from the other in case of a stuck control system or an uncooperative pilot? That would seem to capture the benefits of de synchronizable controls while avoiding the empirically problematic downside.
- spangry 3y agoTL;DR - The pilots failed to engage in a 'positive exchange of flight controls' procedure and ended up providing opposite control inputs at the same time, so it felt to both of them like the controls were unresponsive / jammed. This is a well understood and generic problem in dual-control aviation - see https://www.faasafety.gov/files/helpcontent/Courses/ALC-36/content/index.html#/lessons/FMa2I3Uu-4AfYzF_t6gCoAvssrE-cqkE https://www.faasafety.gov/files/helpcontent/Courses/ALC-36/c... for example. The standard exchange of flight control procedure is designed to create a common understanding between the pilots as to who is in control of the plane. Interestingly it's similar to a TCP three-way handshake: Pilot A: You have control of the plane. Pilot B: I have control of the plane. Pilot A: Acknowledge you have control of the plane.
- AdamN 3y agosyn ... ack ... synack
- WalterBright 3y agoIt looks similar to the 757 design. The 757 has two sets of cables going from the cockpit to the elevator actuators, one set for each pilot. The left pilot controls the left elevator, the right pilot the right. They are synchronized via a cam with a detent (notch) in it. The detent connection enables one pilot to control the left and right cables. The idea is that if one set of cables jams, the pilot can still control his elevator by applying enough force to pop the cam out of the detent. Of course, if both pilots pull hard enough in opposite directions, it will come out of the detent as well. I was one of the engineers working on the 757 elevator system. I don't recall anyone talking about the possibility of the two pilots fighting each other for control. It was just inconceivable. Besides, both pilots would be able to feel the controls "popping" out of the detent. I doubt a warning horn would have made them less confused. I don't know if pilot training included popping out of the detent so they know what it feels like, but it seems like a good idea.
- latchkey 3y ago> I don't recall anyone talking about the possibility of the two pilots fighting each other for control. It was just inconceivable. Suicidal pilot?
- mayormcmatt 3y agoI've seen more than one video from the Mentour Pilot channel on YouTube (where he covers air accidents, fatal and not) where the pilots experience spatial disorientation and input opposite commands on their respective yokes. So it definitely happens on accident.
- WalterBright 3y agoThat was before the era of suiciding airline pilots.
- latchkey 3y ago757... 1983... it wasn't common, but it was a thing... https://en.wikipedia.org/wiki/Suicide_by_pilot https://en.wikipedia.org/wiki/Suicide_by_pilot
- pimpampum 3y agoNeither had slept properly for a 12h? flight: 1.5.5.1 Captain’s statement The captain indicated that it was a flight with difficult hours. He explained that six hours before the flight, he had had a nap of an hour and a half, and that with the co-pilot, they alternated controlled rest periods during the cruise flight. 1.5.5.2 Co-pilot’s statement The co-pilot said it was a tiring flight. He added that they had taken controlled rest during the flight to deal with this specificity. He explained that four hours before leaving the hotel, he had had a nap of an hour and a half to two hours. -- More from the captain statement: The captain noticed that at 400 ft9, the aeroplane had clearly veered to the left. He was surprised. He saw the wheel move 45°10 to the left and did not see the co-pilot correct this. The co-pilot then called out “go around”. According to the captain, this was a critical situation: aborting the approach in a turn with the wheel turned in the same direction. The captain saw the co -pilot make a nose-up input on the control column, press the TO/GA switches and push the throttle levers forward. The power increased but the captain did not see the LNAV TO/GA display appear. The co-pilot then held the wheel with both hands and the pitch attitude became positive. But the wheel was still turned to the left