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As an example, was the 447 computer so deprived of sensory inputs that it couldn't protect the aircraft from nonsensical control inputs - or is there no such software? It seems incredible that systems wouldn't know inputs were illogical. I'm attempting to make a clear distinction between inputs and net flightpath. |
Originally Posted by Loose rivets
(Post 10737548)
As an example, was the 447 computer so deprived of sensory inputs that it couldn't protect the aircraft from nonsensical control inputs - or is there no such software? It seems incredible that systems wouldn't know inputs were illogical. I'm attempting to make a clear distinction between inputs and net flightpath. |
Originally Posted by Loose rivets
(Post 10737548)
As an example, was the 447 computer so deprived of sensory inputs that it couldn't protect the aircraft from nonsensical control inputs - or is there no such software? It seems incredible that systems wouldn't know inputs were illogical. I'm attempting to make a clear distinction between inputs and net flightpath.
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As I see it, the Airbus arithmetical addition of inputs allows an instant, instinctive rescue input to be made even if one does not press the take-over button - to flare the aircraft for example. This is the equivalent of feeling the yoke being pulled back by PM, or having the clutch and brake applied by your driving instructor in a dual control car.
Once when first taxiing an A330, I went off the line at a confusing and poorly lit intersection, at night in an unfamiliar US airport. The TRE slammed on the brakes, which was very dramatic, and it shook up the passengers and crew. Had he simply used his tiller to pull the aircraft back on line, and said to me "I have control" or "no, over here", that would have been that, and no drama, (but the 'Dual input' call might have sounded). The Airbus 'dual input' callout should not be feared, but is a cue for subsequent discussion. |
Originally Posted by Uplinker
(Post 10738015)
As I see it, the Airbus arithmetical addition of inputs allows an instant, instinctive rescue input to be made even if one does not press the take-over button - to flare the aircraft for example. This is the equivalent of feeling the yoke being pulled back by PM, or having the clutch and brake applied by your driving instructor in a dual control car.
Once when first taxiing an A330, I went off the line at a confusing and poorly lit intersection, at night in an unfamiliar US airport. The TRE slammed on the brakes, which was very dramatic, and it shook up the passengers and crew. Had he simply used his tiller to pull the aircraft back on line, and said to me "I have control" or "no, over here", that would have been that, and no drama, (but the 'Dual input' call might have sounded). The Airbus 'dual input' callout should not be feared, but is a cue for subsequent discussion. |
I feel you Uplinker. Was a bit of overreaction. By the way there is no “dual input” auto call out in case of both tiller deflection at the same time. At least not on the A320 family.
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Had he simply used his tiller to pull the aircraft back on line, and said to me "I have control" or "no, over here", that would have been that, and no drama, (but the 'Dual input' call might have sounded). |
Actually, no I don't think there is for steering. Apologies.
Originally Posted by sonicbum
(Post 10738134)
The "dual input" is a big no-no and must not be used, in any circumstance. In Your scenario, if your trainer added his input to yours on the NWS on an A330 in a poorly lit taxiway, that would have been the perfect recipe for wheels on the grass.
My point is that by fearing "Dual Input" even for a second, more drastic intervention is the only course of action left. |
Originally Posted by Uplinker
(Post 10739126)
Actually, no I don't think there is for steering. Apologies.
But in my case the TRE would have steered back towards the correct centreline, arithmetically neutralising my input and taking us away from the wrong line or the grass - while simultaneously saying "I have control", |
Originally Posted by Check Airman
(Post 10578365)
This represents the biggest design flaw of this airplane in my opinion. Not sure why the regulators allowed this to be certified, and (especially after AF447) continue to let it go unchecked. From the AAIB, in a rare moment of clarity (https://assets.publishing.service.go...JZ_12-08.pdf): Simulator assessment The AAIB investigator carried out an assessment exercise in a full flight A320 simulator taking the role of a ‘trainee’ pilot, together with an experienced A320 Type Rating Examiner (Aircraft) (TRE(A)). The TRE(A) was current in both line and base training of pilots of all levels of experience. Having briefed the TRE(A) that he should act as he would during normal operations, the ‘trainee’ flew normal approaches and landings, interspersed with approaches and landings during which deliberate handling errors were made. No prior warning was given to the TRE (A) of these errors. In the first of these ‘unusual’ approaches, a manual approach was flown with autothrust, but the ‘trainee’ ceased to make sidestick inputs at 50 ft RA. The TRE(A) was unable to intervene in time and the aircraft struck the runway without a flare. In other ‘unusual’ approaches, the TRE(A) was again unable to intervene, or intervened too late, to prevent a hard landing. In a fly-by-wire aircraft fitted with sidesticks, the instructor also monitors the approach by assessing the aircraft’s performance, but does not have an option of sensing control inputs made by the trainee. By the time it is apparent that no flare, or an incorrect flare, has been made, it may be too late for the instructor to intervene and the aircraft to respond before a possible heavy touchdown occurs The priority takeover pushbutton is mounted on the top of each sidestick. Whilst control of the aircraft through manipulation of the sidestick is highly instinctive, operation of the priority takeover button is a highly cognitive action. |
Hi sonicbum, trust me, he slammed those suckers on! :)
Originally Posted by Kit Sanbumps KG
(Post 10740663)
..........That sidestick has blood on its hands...
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Originally Posted by Kit Sanbumps KG
(Post 10740663)
Yes.
From the AAIB, in a rare moment of clarity (https://assets.publishing.service.go...JZ_12-08.pdf): and and some proper HF from them: That sidestick has blood on its hands... What a shame manufacturer B has sunk to similar depths and no longer provides a credible alternative. |
Despite over 21000 posts AF447 refuses to die. AF447 and QZ8501 pilots at controls at that time were simply not competent to do what was required and they were not not going to discover it by accident. No pun intended. In 447 TOGA and high pitch and 8501 again pull back on stick. This is not what you do in alternate law. So it is a past time that may be AoA display, oh no! the feedback to the other stick perhaps. It has not happened and not going to happen. We are discussing dual input. These laments are not contributing anything. They should be shifted to 447 thread.
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vilas i think the people talking about AF447 are pointing to the fatal flaw in the system. I think the FBW system is great, but it should never have been designed with uncoupled sidesticks. The extra weight and complexity may have saved the lives of the AF447 pax and crew.
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@vilas while mine opinion differs significantly from C/A's, I do not find your otherwise correct point applicable to this thread.
Yes, the controlling pilots for both AF and QZ made hard to explain inputs after losing spatial awareness. The question why was this not over-ruled by PIC was never answered sufficiently. Reading the QZ report in this respect is heart-stopping. The take-over button only works when you use it, again your note on incompentece are true. Yet the intuitiveness is galaxies apart if you need to correct. Airbus pilots (LHS+) are trained to cope but are they proficient in using the button? What means are there to achieve and maintain such skill? Is it understood that teaching the "I have controls" call and press the button (per FCOM/FCTM) is negative training? |
Originally Posted by Check Airman
(Post 10741682)
vilas i think the people talking about AF447 are pointing to the fatal flaw in the system. I think the FBW system is great, but it should never have been designed with uncoupled sidesticks. The extra weight and complexity may have saved the lives of the AF447 pax and crew.
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Originally Posted by FlightDetent
(Post 10741968)
@vilas while mine opinion differs significantly from C/A's, I do not find your otherwise correct point applicable to this thread.
Yes, the controlling pilots for both AF and QZ made hard to explain inputs after losing spatial awareness. The question why was this not over-ruled by PIC was never answered sufficiently. Reading the QZ report in this respect is heart-stopping. The take-over button only works when you use it, again your note on incompentece are true. Yet the intuitiveness is galaxies apart if you need to correct. Airbus pilots (LHS+) are trained to cope but are they proficient in using the button? What means are there to achieve and maintain such skill? Is it understood that teaching the "I have controls" call and press the button (per FCOM/FCTM) is negative training? It is up to ATOs and Operators to establish training policies and procedures in such a way that pilots are and remain proficient with the proper takeover technique. It is important to clear bad habits and insist on the usage of the proper technique which can be practiced during simulator sessions with the instructor occupying the other pilot seat. In my company the flight safety team has a very pragmatic and common-sensed based approach on event management but "dual inputs" are highly not tolerated (like an unstable below 500ft), including during training flights, because it can lead to very serious events. |
Originally Posted by sonicbum
(Post 10742551)
The "uncoupled" sidesticks has nothing to do with the AF447 accident and I personally believe that there was not at the time and still there is not any need for such a thing as there is zero evidence from past accidents that it could have changed the course of action.
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Originally Posted by Report PK-AXC
38. Since 2317:29 UTC, both left and right side stick input were continuously active until the end of the recording. The inputs were different where the right sidestick was pulled for most of this segment, the nose down (forward) pitching commands of the left sidestick became ineffective because of the summing function of the system, resulting in ineffective control the aircraft.
Although there were at least 3 other things that could have helped avoid the outcome. All mandatory for airline pilot competence and none of them demonstrated by the crew. That is also true. |
Originally Posted by FlightDetent
(Post 10742661)
If there was a dotted line below: "...there is zero evidence from past accidents ... (interconnected side-sticks) ... could have changed the course of action" I would not sign. :(
Although there were at least 3 other things that could have helped avoid the outcome. All mandatory for airline pilot competence and none of them demonstrated by the crew. That is also true. |
Aren't the fact the sidesticks are not linked a matter of principle, not complexity/weight?
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In post #38 I have termed the dual input or noncoupled side sticks as the Achilles heel of Airbus. So I haven't denied that. I had commented on 447 thread that even if it was empathized in classroom that in alternate law you should not pull full back stick even with GPWS could have saved both the aircraft. Airbus by it's philosophy is automation. Now it has come out with alternate speed where with unreliable speed situation aircraft tells pilot it has switched to alternate speed and he doesn't do a thing. Accidents happen even with everything in place as it should be. My point was 447 has been discussed threadbare and we should not be trading the worn out path.
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Aren't the fact the sidesticks are not linked a matter of principle, not complexity/weight? Building them connected and movable, with sufficient reliability while observing fail-safe/operational criteria, was such an engineering and economical puzzle that decision was to go independent-redundant. So I was told. The present configuration has a number of its own unique benefits as well. Good skills of a proficient operator are built around the fact they are not interconnected. Tools to mitigate the undesirable consequences are provided in hardware, software and liveware. Using those instinctively, as a reflex action, that is where the chosen solution cannot compare to connected yokes. https://www.alamy.com/stock-photo-co...-73187853.html |
Originally Posted by Check Airman
(Post 10742657)
It’s my opinion that the PM would’ve been able to rectify the situation, had he realised the PF was pulling back the whole time.
In theory, the side-sticks could be linked mechanically with a series of 90° cranks and two control rods crossing from one stick to the other just behind the lower part of the instrument display panel, and a release pin in each rod could be pulled in an emergency to separate the sticks. Knowing what the other side-stick is doing need not require mechanically linked sticks: The Maltese cross and four corner display used for control ground checks could be brought onto both PFDs in flight under certain circumstances, so the other pilot would see what control inputs were being applied, and thus be aware of the need to apply their take-over button if required. |
Still haven’t had any confirmation that the original A320 did not even have the Dual Input warning and that it was a modification. Can anybody confirm this.
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Originally Posted by Uplinker
(Post 10743532)
In theory, the side-sticks could be linked mechanically with a series of 90° cranks and two control rods crossing from one stick to the other just behind the lower part of the instrument display panel, and a release pin in each rod could be pulled in an emergency to separate the sticks.
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The Connected SS can be helpful but I think the tactile feed back and soft stop is not in synch with Airbus FBW i.e. flight path stable. It will be too much contradiction. The other thing I want to know is in any aircraft in instrument conditions when a pilot wants to make a pitch change isn't he supposed to look at the PFD to know it's happening? Maybe if instinctively an input is given without reference to PFD but at least afterwards is he not supposed to check that the correct amount of change has happened? In 447 case a very high input was given and was never checked by any of them. OK the side sticks are not connected but in clouds with AP disconnected the PM never looks at PFD then what was he monitoring?
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vilas Agreed 100%.
Uplinker The risk of overloading pilots with clutter on the PFD is real. Hence the removal of non-essential indications during abnormal attitudes, on various installations. Having said and personally being happy with that, I cannot stop thinking every now and then if the maltese cross could be helpful. OTOH, being devils advocate against myself: - The improper use of maltese cross has caused trouble before and due to P.C. / L.o.F issues, the indication is somewhat exiled. - There would be a need for training and assuring proficiency. An argument is raised such training effort and resources are better utilized to help pilots excel in using the present configuration. tcasblue Posted in #66 https://safetyfirst.airbus.com/app/t...ick-inputs.pdf, the end of the article has an inset. HOW TO UPGRADE YOUR SA AND LR AIRCRAFT ? The light and aural indicators are basic and free of charge on retrofit, on the A320 family and A330/A340. It requires FCDC and FWC to be at a given standard already available on production line: • A320: FWC E2 Standard - FCDC 53 Standard • A330/A340: FWC K3/L7 Standard - FCDC M11/L14 Standard Pin progra Chris Scott Hope all is well, good sir. Any war stories to share? |
Originally Posted by vilas
(Post 10743929)
The Connected SS can be helpful but I think the tactile feed back and soft stop is not in synch with Airbus FBW i.e. flight path stable. It will be too much contradiction. The other thing I want to know is in any aircraft in instrument conditions when a pilot wants to make a pitch change isn't he supposed to look at the PFD to know it's happening? Maybe if instinctively an input is given without reference to PFD but at least afterwards is he not supposed to check that the correct amount of change has happened? In 447 case a very high input was given and was never checked by any of them. OK the side sticks are not connected but in clouds with AP disconnected the PM never looks at PFD then what was he monitoring?
If, additionally, a force proportional to speed deviation is fed back, that would make it speed stable and incompatible with what Airbus does. But nothing means that has to happen. The only other force could be a spring force from center, as is the case now. |
Originally Posted by Goldenrivett
(Post 10743582)
I think these active side sticks will be the final solution Active Side Sticks
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I am basically reluctant to reopen AF447 because it's waste of time. There were 22000 posts before it closed and I don't think anything new can be added. Also Airbus gave a thought about linking SS but didn't. If it didn't happen then it's not going to happen now.
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Originally Posted by FlightDetent
(Post 10743972)
tcasblue Posted in #66 https://safetyfirst.airbus.com/app/t...ick-inputs.pdf, the end of the article has an inset. . Not a direct proof though. If true, there could be some aircraft out there without the Dual Input upgrade. Anybody have that situation at their airline? |
Agree with the last few posts.
I personally think the Airbus FBW is a fantastic piece of design, and is well developed and thought out; credit to the design team. I find it a delight to fly and, coming from an old style basic jet, (the BAe 146), I found Airbus FBW easy and completely intuitive, (I do have an electronics background, and can appreciate why the system works the way it does - perhaps that helps). I was type rated onto a B737-300/400 for a season two years ago and that was like something from the stone-age, by comparison. (Now happily back on A330 again, Covid 19 allowing). As far as Dual Input goes and without contradicting myself, I would be curious to know the Airbus design team's reasoning on the cadet 'no flare' scenario and the other situation of not always being able to see the other side stick, particularly on a dark flight deck with the opposite tray table out. |
Originally Posted by Uplinker
(Post 10578258)
If a pilot does not flare at 10’ there isn’t really time to say I have control, you just need to take control. With a conventional yoke system, a Trainer or Captain could apply back pressure on their yoke which would save the landing and give feedback to the trainee, (followed by a debrief). The Airbus FBW side-sticks do not move to mirror each other’s inputs - (I think they should) - so instead there is an algebraic addition of deflections. This means that in a no flare situation, the Trainer/Captain could quickly pull back and save the aircraft, but it is not correct for both pilots to be operating the controls, hence the “dual input” warning if the take-over button is not also pressed. Airbus FBW nosewheel steering is also additive, and I once saved a Captain who suddenly veered over (for some reason) while taxying, and I grabbed my tiller and saved any embarrassment. There wasn’t time to alert him or say I have control. |
If some of you are actually airline pilots, this is a profoundly disturbing thread. The AAIB report referenced above laid bare the appalling weaknesses in airbus philosophy. I’m sympathetic to how they got there, but not their absolute refusal even to discuss that they might be wrong. Declining professional standards plus this kind of nutty design add up to foreseeable problems that may kill.
To answer Uplinker , I asked them, from a professional position of authority, and they didn't have an answer. Being ‘able’, in terms of flight deck layout and illumination, to see the opposite sidestick, and being able to monitor it continuously and effectively and in a sufficiently granular way without detriment to more general situational awareness, are hugely different things. Interconnected controls, and the fabulous nature of the human haptic system, are the answer, unless you live in Toulouse. |
Originally Posted by CayleysCoachman
(Post 11758073)
If some of you are actually airline pilots, this is a profoundly disturbing thread. The AAIB report referenced above laid bare the appalling weaknesses in airbus philosophy. I’m sympathetic to how they got there, but not their absolute refusal even to discuss that they might be wrong. Declining professional standards plus this kind of nutty design add up to foreseeable problems that may kill.
To answer Uplinker , I asked them, from a professional position of authority, and they didn't have an answer. Being ‘able’, in terms of flight deck layout and illumination, to see the opposite sidestick, and being able to monitor it continuously and effectively and in a sufficiently granular way without detriment to more general situational awareness, are hugely different things. Interconnected controls, and the fabulous nature of the human haptic system, are the answer, unless you live in Toulouse. After operating Toulouse engineered aircraft for almost 20 years and instructing almost half of that time, I never had a single issue with that design. And I trained quite significant number of cadets, including base training. Comparing a Toulouse designed aircraft with a Seattle ones, there is quite obvious difference in the number of incidents recorded by NTSB https://cimg7.ibsrv.net/gimg/pprune....5c7ea2286.jpeg |
Originally Posted by Cak
(Post 11758513)
Comparing a Toulouse designed aircraft with a Seattle ones, there is quite obvious difference in the number of incidents recorded by NTSB
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Wow, Cak that graph is an appalling abuse of data, as Vessbot explains on his thread. The central point is that the use of FBW should, if correctly executed, have had a positive impact on risk. It hasn’t, and while we will never know which deaths were prevented by it, we know that deaths have been caused by it, IN THE WAY THAT AIRBUS INSISTED UPON ENGINEERING IT (sorry for shouting but the point needs to be made forcefully).
Their corporate mental model that it was a cure-all was equally damaging - I still have a copy, somewhere, of their letter to operators which stated that UA recovery was not a necessary syllabus item on their products. |
« It’s not the plane. It’s the pilot ». Not taking any sides. Let’s be real: Any competent pilots should be able to fly safely an Airbus or a Boeing. But the outcome might have been very different in the Hudson river case if it was a conventional aircraft; Not taking any credits from Cpt Sully, he did an amazing job. Just stating facts: Side stick was held fully back but thanks to the protection they did not stall. Also Alpha floor had saved many aircraft from stalling in some cases like interception from above going seriously wrong like in the case of Air France 7512.
https://bea.aero/fileadmin/user_uplo...19-0731.en.pdf |
Ah, the good old Airbus vs Boeing threads! We were missing it!
Come on, “can we get serious now?” |
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