Dual Input Airbus

[MD83FO]

I've come across a number of pilots who claim that during a late flare from the F/O and in order to save a potentially hard or firm landing, pump the side-stick at short intervals in a way that the dual input doesn't sound.

I have never done it, just keep my finger in the red button hoping i don't have to use it.

my understanding according to the algebraic design, is that it would be necessary to deflect ones sidestick beyond the other's deflected amount, to cause an additional elevator response.

what do you think about this underdog common practice?

[Global Aviator]

Hmmmmm I’m calling BS!!!

[The Old Swedish]

It is true that the dual input warning in the cockpit is not triggered if the PM deflects his sidestick within a certain limit. But even without an aural warning it will be recognized by your flightsafety department.

I am sayin BS as well.

[AmarokGTI]

What’s the goal here? To take over/assist Without them knowing? Can’t see any benefit in that.

[deja vu]

I've come across a number of pilots who claim that during a late flare from the F/O and in order to save a potentially hard or firm landing, pump the side-stick at short intervals in a way that the dual input doesn't sound.

I have never done it, just keep my finger in the red button hoping i don't have to use it.

my understanding according to the algebraic design, is that it would be necessary to deflect ones sidestick beyond the other's deflected amount, to cause an additional elevator response.

what do you think about this underdog common practice?
I call it irresponsible and dangerous. It reminds me of a certain Captain I knew who felt that all that mattered was a super smooth touch down so he wouldn't fully retard one thrust lever so only part spoilers would deploy and hence not dump the front end of the bogey on the 330. Then all he had to do was stop the aircraft before the end, er....

[Check Airman]

I've come across a number of pilots who claim that during a late flare from the F/O and in order to save a potentially hard or firm landing, pump the side-stick at short intervals in a way that the dual input doesn't sound.

I have never done it, just keep my finger in the red button hoping i don't have to use it.

my understanding according to the algebraic design, is that it would be necessary to deflect ones sidestick beyond the other's deflected amount, to cause an additional elevator response.

what do you think about this underdog common practice?

I think that’s not the way the side sticks work. If that mechanism is to be believed, then the PM’s small amplitude deflections would have no effect.

[iceman50]

Why not just call "flare" to the FO.

[deja vu]

Why not just call "flare" to the FO.
There plenty of auto call outs to cue the flare, vary a little of course with conditions on the day, last thing needed is another unannounced input.

[vilas]

I've come across a number of pilots who claim that during a late flare from the F/O and in order to save a potentially hard or firm landing, pump the side-stick at short intervals in a way that the dual input doesn't sound. I think this thought originated from incomplete understanding of the system. First thing, even a small movement out of neutral will give a command to change the pitch and depending on what the other stick is doing it will impart the LF or AoA as demanded if other stick is neutral, added if the other stick is moved in same direction or subtracted if other stick is moved in opposite direction. Dual input will sound when the sticks are moved beyond 2°. Once on two consecutive Landings the FO didn't flare at all so I flared at 10ft. and let go. He was happy with the result. I told him you didn't flare I had to flare. He said but there was no " Dual input". I said that's right there was no dual input but the single input was mine. I should have taken priority. The practice of fiddling with stick is senseless will give confusing results. The correct practice ask him to flare or press TO button and do it yourself. There's no follow me on controls in Airbus.

[pineteam]

I totally agree with you Vilas. Dual input should be prohibited. Sadly, I have seen many skippers abusing of it including instructors... :}

[iceman50]

deja vu

My comment of "Why not just call "flare" to the FO" was for those that are worried about the FO flaring late. Not giving an extra call, unless it is required.

[joe falchetto 64]

I totally agree with you Vilas. Dual input should be prohibited. Sadly, I have seen many skippers abusing of it including instructors... :}


It is a common practice in SE Asia. I say "common" but not "right".

[vilas]

It can be called nervous twitch because it doesn't do any GOOD. If it did Airbus instructors would have suggested it. Pilots allowed to give takeoff and landing should be given a practice of take over with the button. It's a tricky part. Instead of fiddling with the stick you need your thumb on the button to quickly take over. As it happened in the Jetstar Australia incident the guy yanked the stick to raise pitch 21° the trainer was unable to intervene resulting in bad tail strike.

[Centaurus]

last thing needed is another unannounced input.
You mean like "Oh sh*t"

[FlightDetent]

my understanding according to the algebraic design, is that it would be necessary to deflect ones sidestick beyond the other's deflected amount, to cause an additional elevator response. My understanding is significantly different. The individual deflections are added up, and the sum then fed to the F/CTL computer. Any deflection will have an effect.

[sonicbum]

A very important aspect is to properly brief new trainees FO/Captains/Instructors on the fact that, unlike other "conventional" aircrafts where a little help is given to avoid digging a hole and spending the turn around with paperwork, on the Airbus FBW family there will be a takeover from the Captain/Training Captain should the need arise, that this is perfectly normal and there is no other way around. In my experience spending a few words with the trainees prior to their first flights and emphasising this aspect has proven beneficial in order to avoid potential demotivation and drop in performances following a low height takeover. It is then up to the trainer/captain to set their own threshold to what is acceptable and what is not according to each own's level of experience, but a takeover is always the right and only option if we are not happy with anything. It is better to have a takeover when it was not really needed than the opposite, and with time everybody can adjust their own tolerance.

[Mr Optimistic]

Pax so disregard if displaying idiocy. If you were to input little nudges to correct, wouldn't the other guy think he had nailed it and risk embedding a wrong model in his/ her head?

[Goldenrivett]

Pax so disregard if displaying idiocy. If you were to input little nudges to correct, wouldn't the other guy think he had nailed it and risk embedding a wrong model in his/ her head?
Only if it wasn't debriefed when work load allowed.

[vilas]

My understanding is significantly different. The individual deflections are added up, and the sum then fed to the F/CTL computer. Any deflection will have an effect
FD, algebraically added. Absolutely correct.

[deja vu]

My understanding is significantly different. The individual deflections are added up, and the sum then fed to the F/CTL computer. Any deflection will have an effect.
But...Isn't that dangerous? Whatever happened to "I have control." I forget how long the take-over button takes, 5 seconds maybe

[Uplinker]

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.

[Check Airman]

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.

[dogsridewith]

Why is "I have control" not "Mine?"

[Check Airman]

Why is "I have control" not "Mine?"

Depends on the airline. My previous company was much more aligned with Airbus SOP. We said “I have control”. Current company says “my aircraft”. They’re fairly strict on that in the training department. “My airplane” will get you slapped on the wrist.

[sonicbum]

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.

It works perfectly well if you know how to do it and set yourself some reasonable gates. Intervention training is generally part of upgrade courses and is a big part of TRI courses. When we do qualify TREs for base training we spend at least an hour each in the sim to practice all sort of mismanaged handling at low height, it just takes a bit of practice.

[Uplinker]

Why is "I have control" not "Mine?"

Because in the heat of the moment, “mine” could be misheard, and misunderstood.

Many standard phrases might seem laborious, but they are designed to avoid any confusion, and be understood over background noises etc.

[Check Airman]

It works perfectly well if you know how to do it and set yourself some reasonable gates. Intervention training is generally part of upgrade courses and is a big part of TRI courses. When we do qualify TREs for base training we spend at least an hour each in the sim to practice all sort of mismanaged handling at low height, it just takes a bit of practice.
As Uplinker said bout the heat of the moment, sometimes there’s no time. An easy, intuitive solution to the problem they created is used by Boeing, Douglas (RIP) etc. Airbus put a lot of energy into human factors, but the uncoupled sidesticks (particularly in with the AP off) is a huge oversight, and fatal, as we’ve seen.

[sonicbum]

As Uplinker said bout the heat of the moment, sometimes there’s no time. An easy, intuitive solution to the problem they created is used by Boeing, Douglas (RIP) etc. Airbus put a lot of energy into human factors, but the uncoupled sidesticks (particularly in with the AP off) is a huge oversight, and fatal, as we’ve seen.

Sorry, but I disagree. You do have time to press the takeover pushbutton, it takes 1 millisecond regardless of the words You pronounce, if any. Being able to judge when it is appropriate to press this button is another question though and that comes also with experience, I believe we all acted with our thumb at least once either a bit too late or a bit too early (at least I did luckily without breaking anything). The basics is any time You are PM and need to act on the sidestick for whatever reason, You push the button.
Regarding the AF447 You are referring to, if You end up with 10 degrees ANU and TOGA at FL350 I believe (and much more important investigation bureaus believe) it is somewhere else we need to focus on rather than the mechanical connection between the sidesticks.

[The Banjo]

Capt presses red button, aircraft announces, "priority left", capt lands aircraft and discusses flare technique with first officer at bay after shutdown.
No "tea n' bikkies" with management as heavy landing avoided, first officer's 21st century ego takes back seat and everyone goes home happy.
Not difficult.

[vilas]

If a pilot does not flare at 10ft there isn’t really time to say I have control, you just need to take control. if you are flying Airbus why do you have to say anything? The aircraft will say that for you. Priority left is same thing. Just press the take over button, flare and land. Tell the FO to do a better job next Landing.

[ACMS]

if you are flying Airbus why do you have to say anything? The aircraft will say that for you. Priority left is same thing. Just press the take over button, flare and land. Tell the FO to do a better job next Landing.

At 10’.........too late, all over red rover by then......

[vilas]

At 10’.........too late, all over red rover by then......
Not necessarily. All you need is to break the descent. It can be done at 10ft. But if you feel it's too late then you should do it while crossing 20ft. In the aircraft some one needs to do what is required to be done. If AP doesn't then pilot, if PF doesn't then PM has to. And the last barrier needs to be defined according to individual judgment. Cannot continue accepting hard Landings till the FO develops the judgment.

[Check Airman]

Cannot continue accepting hard Landings till the FO develops the judgment.

Who said anything about FO’s doing hard landings?

:}


On a more serious note, it is concerning when airlines never allow FO’s to fly in challenging conditions, then hand the keys to the jet to those same FO’s after upgrade.

[iceman50]

You are all obviously talking about the A320 variants as flaring at 10' on A330/A340/A350 will only drive the mainwheels into the ground harder! Intervention should have happened well before then.

[vilas]

Iceman, no! I didn't suggest flaring at 10ft. but ten ft as salvaging point in A320.

[PGA]

Also an important thing to note:

dual input as opposed to pressing the takeover button can save the day sometimes. If your colleague doesn’t flare enough, the moment you press the button the flight control does what.......? Back to neutral until, your input is established, which could make matters worse temporarily.

[hikoushi]

Sometimes a combination of instinct and procedure is the right technique. The time that most of us will instinctively move the stick (“DUAL INPUT!!!”) before pressing the takeover PB is either a quick pull when the guy forgets to flare, or a quick lateral move when the guy over-banks suddenly. The “OH S#!T” pull will always happen before the button gets pressed! Adrenaline will ensure this!

In the opposite situation with someone over-flaring, we will naturally tend to press the button first. This will in actuality return the controls to neutral since we likely will not have actually moved the stick yet... which is exactly what we need to do.

Simply following instinct will always work, as long as we remember to press the takeover button at some point in the proceedings. To prevent a hard landing or a wing/pod strike, make the instinctive move first and then press the takeover button while applying the stick pressure. For a high/ over-flare, press the button first and then fly the airplane where you want it to be. Either way is natural and is what most of us will do without thinking about it.

[vilas]

There's a difference between not flaring and not enough flaring. In not flaring at all the PF stick is in neutral so if the other pilot flares then it's single input and the aircraft response is normal. Not flaring enough the PF stick is out of neutral, here any input from the other side will be additive to it. Since flare and Landing is a visual manoeuvre if one is able to differentiate the change in flight path and adds his input accordingly then it will still produce the desired result even with dual input warning. The problem is if the PF for some reason pushes the side stick forward then the PM input will be cancelled and aircraft will continue it's Flight path. So the gist is if is you want to salvage the Landing you will have to do something in an approved or not approved manner. If the result is not satisfactory execute a GA. This the Achilles heal of Airbus FBW so perhaps the discomfort makes each one find his own solution.

[tcasblue]

I found this statement from another forum to be interesting. Perhaps not in the original design......

"There is a "dual input" audio callout. It was a early A320 mod, but I think it was standard before the A319 came out."

[Loose rivets]

I suppose flying allows one to get good at expecting the unexpected, but having got old, and sitting in an ATR watching a very able young man fly the sector, I was reasonably relaxed as we passed 200'. At some point, I'm not sure when, the concrete suddenly looked like it was coming through the windshields.

I'm not sure why it happened, or even how he managed it, other than it was flown, not mushing. What I do know is that with any delay, the aircraft would not have survived the impact. My frantic tug allowed one of those 3-point landings that don't allow the wheels to skid before spinning up. Despite my best efforts, exchanges in English were somewhat limited and I'll never understand, but it seems to me that a large aircraft, stacked with computing power, should be capable of protecting itself from pilot input that makes no sense.

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.

[vilas]

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. If aircraft had all that you are suggesting would you still be expecting to get paid?

[Check Airman]

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.

The computers are only as good as the data they’re being fed. For a while, the data was inappropriate, and so the computer handed full control back to the pilot. The designers knew the computer can’t act on bad data. I’ve sat in the A320 and watched it do stupid things. I don’t want the plane to be overthinking my inputs.

[sonicbum]

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.

There is not a single aspect of AF447 that has not been discussed on this forum over the past 11 years. I am sure your question has an answer !

[Uplinker]

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.

[sonicbum]

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.

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.

[pineteam]

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.

[vilas]

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). Dual input for steering? Are you sure?

[Uplinker]

Actually, no I don't think there is for steering. Apologies.


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.

In normal ops, I agree; it should be a very rare occurrence. 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", or GENTLY applying the brakes. (we weren't heading for the grass by the way :))

My point is that by fearing "Dual Input" even for a second, more drastic intervention is the only course of action left.

[sonicbum]

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",



I understand your point, but imagine had he done that, perhaps you would have then let go the NWS completely. The aircraft would have veered abruptly on the other side, as there would have been suddenly no inputs to be neutralised... as for slamming the brakes, I was not there so can't tell if it was an overreaction or not, but as You know we all have different "limits" so in the end better safe than sorry. Anyway since as of today almost nobody is flying it's going to be interesting to see who is going to take over who once we get back in the saddle ;-)

[Kit Sanbumps KG]

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.

Yes.

From the AAIB, in a rare moment of clarity (https://assets.publishing.service.gov.uk/media/5422f3ca40f0b613460004f5/Airbus_A320__G-DHJZ_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.

and

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

and some proper HF from them:

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.

That sidestick has blood on its hands... What a shame manufacturer B has sunk to similar depths and no longer provides a credible alternative.

[Uplinker]

Hi sonicbum, trust me, he slammed those suckers on! :)

..........That sidestick has blood on its hands...

That's putting it a bit strong. Do the thrust levers that did not move on the 777 crash at SFO have 'blood on their hands'?

[sonicbum]

Yes.

From the AAIB, in a rare moment of clarity (https://assets.publishing.service.gov.uk/media/5422f3ca40f0b613460004f5/Airbus_A320__G-DHJZ_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.

What a load of rubbish. Have You haver flown a FBW Airbus ? Are You a trainer on it ? Do you have any idea what you are talking about ?

[vilas]

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.

[Check Airman]

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.

[FlightDetent]

@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?

[sonicbum]

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.

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.

[sonicbum]

@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?

If I can add my 2c...
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.

[Check Airman]

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.

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.

[FlightDetent]

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. 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.

[Check Airman]

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.

Agreed. To be clear, my opinion on the sidestick thing isn’t the only thing that brought them down. I was only focusing on one link in the proverbial chain.

[Lord Bracken]

Aren't the fact the sidesticks are not linked a matter of principle, not complexity/weight?

[vilas]

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.

[FlightDetent]

Aren't the fact the sidesticks are not linked a matter of principle, not complexity/weight?
My understanding is negative on this one. To have them the way they are is not a result of applying any specific operational philosophy. I.e. it was not a design objective to create a solution with separate sticks.

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-cockpit-de-havilland-canada-dhc-6-twin-otter-hydroplane-maldives-73187853.html

[Uplinker]

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.

I agree with you on that, (but no pilot should ever think it acceptable or correct to apply full pitch up at 36,000 in the first place, no disrespect intended to the AF447 crew).

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.

[tcasblue]

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.

[Goldenrivett]

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.


I think these active side sticks will be the final solution Active Side Sticks

[vilas]

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?

[FlightDetent]

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/themes/mh_newsdesk/documents/archives/dual-side-stick-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. Not a direct proof though.

Chris Scott Hope all is well, good sir. Any war stories to share?

[Vessbot]

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?

I don't see a contradiction between linking the sticks and the Airbus control law. That just means the other pilot's hand force is fed into your stick, and doesn't necessitate anything more.

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.

[Denti]

I think these active side sticks will be the final solution Active Side Sticks (https://youtu.be/3sXXx8rgeeE)
Airbus considered active side sticks during development, the DLR (back then DFVLR) had test items, including interconnect, developed for a test rig, but it never went very far as other decisions had been taken quite early, vilas explained it quite nicely why it doesn't work well with the current FBW philosophy of airbus.

[vilas]

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.

[tcasblue]

tcasblue Posted in #66 https://safetyfirst.airbus.com/app/themes/mh_newsdesk/documents/archives/dual-side-stick-inputs.pdf, the end of the article has an inset.
. Not a direct proof though.

Thanks,

If true, there could be some aircraft out there without the Dual Input upgrade. Anybody have that situation at their airline?

[Uplinker]

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.