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Airbus takes pilots back to basics with the A350

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Airbus takes pilots back to basics with the A350

Old 15th Oct 2012, 00:24
  #241 (permalink)  
 
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Pushing the stick on Airbus will reduce the pitch, it will not automatically make the aeroplane descend.
LOL
You admit now that the Airbus is not a plane "like other" ?
So what is needed more than push forward the stick for the Airbus descend ? (pointing noze down .. of course .. as we also know that a Airbus can descend when pulling the stick)
All passengers forward in a hurry (Das boot .. alaaarm .. tauchen .. tauchen !!) .. or tranfer fuel to the noze ?

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Old 15th Oct 2012, 00:54
  #242 (permalink)  
 
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I think between the a/c maintaining 1G (in climb), and Pf fearing less than one G as the beginning of overspeed ("dive"), he locked the ac functionally into a one gee projectile that was doomed to STALL. As Retired F4 pointed out, the aC maintains positive g, it would take severe ND input to descend, even before the zoom climb. Pf initial Nu sealed the deal? Plus, when the ac dropped from 7000fpm to 1100fpm, he'd had enough 'negative', thank you very much..

Last edited by Lyman; 15th Oct 2012 at 00:57.
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Old 15th Oct 2012, 08:10
  #243 (permalink)  
 
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When I went through Airbus training in the mid-2000s, the first session was flown in direct law to show me that it flew "like an airplane."
No it doesn't. In DIRECT LAW you have an airplane that flies like the microsoft flight simulator. NORMAL LAW resembles better how an airplane flies, only it is always in trim, so to speak. In direct, there is absolutely no feeling of the aerodinamic forces, a given elevator deflection Feels exactly the same at 140 kt and at 350 kt. It does not fly like an airplane. It does in normal law.
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Old 15th Oct 2012, 09:08
  #244 (permalink)  
 
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This can under no circumstances be called feedback. Any feedback involves return information. There is no any return in your examples as you are not the originator!
As a flightcrew we ARE the originator. Flying is not an individual game on airliners, we operate the aircraft as a crew not as individual pilots.
We put information into the FMGS into the FCU/FCP or into the sidestick/yoke. So whatever way you put it moving controls give sensory information with regards to the commands the the flightcrew gave to the aircraft either through automatics or manual flight.

But why get hung up on the word feedback? The rest of what is being said is much more important.

Feedback from aeroplane. Observed on instruments or by looking out the window in flare. Of course, I'm the lucky b'stard that can do both things at the same time.
I thought there was no such thing as feedback on modern airliners...
You can't do both things at the same time unless you have a HUD or you look like this:



And before you reply think "at the same time"

Pages from 17 onwards shatter the myth of hard landings being caused by airbus flight control architecture (except that infamous Bilbao case, included here and neatly explained) or that interconnected yokes will prevent it.
It doesn't shatter anything... I never stated that hard landings don't occur on aircraft with interconnected yokes. Most hard landings result from unstable approaches in fact most landing incidents and accidents result from unstable approaches.

This however does not mean that the airbus FBW does not play a role, and not every firm landing that undergoes subsequent maintenance inspection is an incident or accident

But why o why would the AAIB write this?:

Use of the takeover pushbutton is not instinctive and previous accidents investigated by the AAIB have revealed instances involving Airbus fly-by-wire aircraft types where non-handling pilots have failed to use the button when making control inputs to correct those of the handling pilot. The Civil Aviation Authority also has other evidence where failure to use the takeover button has caused additional aircraft control problems.
The Airbus fly-by-wire aircraft types are unique in commercial aviation in that it is not possible for one pilot to feel what the other pilot is doing with his or her sidestick. In brief, there is no force or position feedback from one sidestick to the other and in the air, there is no stick position information on the flight instrument displays. Consequently there is no practical method of 'assisting' the handling pilot by making a control input on the other sidestick, particularly if the handling pilot is also moving his or her sidestick at the time. The result of two sidestick inputs is a blend of both and, since the aircraft's reaction is inconsistent with its normal 'manoeuvre demand' response, the resultant response cues may seem abnormal for both pilots which in turn, can provoke more extreme sidestick inputs.
Oh did you see that even the AAIB call it force or position feedback from one sidestick to the other. Could you please contact them that their use of the word feedback is inappropriate.

Last edited by 737Jock; 15th Oct 2012 at 10:26.
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Old 15th Oct 2012, 10:11
  #245 (permalink)  
 
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and he said some early airline instructors had tried to concentrate on the bells and whistles, not on the airplane.
Nothing new there. Instructors still do that on Boeing initial simulator training; which is a great pity as this starts the new pilot on the inevitable road to automation dependency.
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Old 15th Oct 2012, 12:58
  #246 (permalink)  
 
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sciolist ...

Originally Posted by Clandestino
Because outside PPRuNe not much relevance is attached to it.
The Airbus sidestisk philosophy suppresses valuable information to a PNF.
This is a reality documented not only here on PPRuNe, but also by the AAIB … Are they unscrupulous or sciolists as well ?
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Old 15th Oct 2012, 19:12
  #247 (permalink)  
 
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@ clandestino:
Just as a reminder: The reason to make a comment in this thread was the highlighted part of your post 109 of this thread

Clandestino post 109
3. if you just bothered to read and understand Davis, he explicitly mentions shaker and pushers are only fitted to aeroplane with unacceptable stall characteristics i.e. no pres-stall buffet or tendency to deep stall. It is painfully obvious that AF447 did not roll, did not flick, did not spin and it took all the effort of the CM2 to hold it stalled, as soon as he released the stick, nose plunged down towards recovery
This last part of your post is not only wrong, it might be deadly wrong. If a PF in the situation of AF447 in an A330 in ALT2B law would just release the stick and wait on the nose plunging down he might end up like AF447 did.

I didnīt make any fuss of that and it was and is nothing personal against you (why should it be?), has nothing to do with your person, nothing to do with your general views of of posts here and nothing to do with my personal oppinion. I have no axe to grind with airbus or any other manufacturer and i donīt earn money by posting here or in any other internet forum.
I explained my position in my post 163 based on FDR analysis and i think i did it sound and understandable and unbiased. My conclusion stands, that there are lots of other factors than elevator position or SS position alone for the four consecutive nose drops of AF447 in the referenced stalled situation mentioned by yourself. Whats wrong with that? Do you have another information which i myself or other readers dont have, which would support your statement

as soon as he released the stick, nose plunged down towards recovery
and the followup explanation

Good catch! Thank you for pointing to me being far less than pedantic. It was not mere stick release, right stick went forward of neutral between approximately 2:12:35 and 2:13:50. Elevator is out of full-up between 2:12:40 and 2:13:15. Pitch goes from +10 to 0, back to 7 then down to -10.
thus implying (after correcting the first part of your wrong overall statement), that the nosedrop was caused by putting the SS something forward of neutral for a brief time while disregarding the fact, that the first not mentioned nosedrop and the last nosedropp happened while SS was held full NU and elevators were full NU as well, and thereby overlooking a lot of other factors which may have led to the first nosedrop and may have caused alone or helped the other nose drops? Even flying is not as simple as that and a stall recovery is the most difficult part of flying and a lot more difficult than your comment states.

Clandestino
Originally Posted by Retired F4
And your conclusion, that the reduction in pitch was caused due to the SS nosedown inputs lacks the necessary proof.

Clandestino:
This would be true if the elevator was the only thing keeping the nose up. Underslung engines at high power and low speed helped immensely, too. One average reduction in pitch (that is center of the bobbing) is consistent with reducing the power, two with elevators moving from their stops, consistent with stick movement.
Now you name one of many factors yourself, but omitted them in your post which i referred to. Itīs quite a difference, donīt you think so?

Originally Posted by retired F4
The conclusion that a "release of SS caused a plunge" canīt be derived from the available information, and thatīs most probably the reason that BEA didnīt state something like that. They actually saw a lost case early in the event.
Clandestino:
So you are making a case around my one imprecision that I thanked you for refuting. Be my guest. ........
The case is AF447, which doesnīt need to be made up. It is real. No case about you.

Clandestino
Originally Posted by retired F4
All those factors interact together and produce a near random output, therefore, the conclusion of Clandestino imho is far fetched.
Clandestino:
Why? Just because Clandestino made it? Dear Retired F4, if it is so random, how come you are making such a bold analysis in this post?
There is nothing bold with my analysis and imho nothing wrong with it. It is my personal analysis based on evidence (the FDR data) and marked as my personal opinion not to be misunderstood as fact. I will object and have objected absolute statements which look quite wrong like the one discussed here and that are not based on evidence or on inaccurate evidence regardless who postīs them. It has nothing to do with the name, nationality gender or viewpoint of the poster. Thereīs a differenc to my answering on postīs though. While iīm not commenting on postīs of trolls or on posts already discussed to death by other posters i find it important to take part in discussion of posts from respected posters with enough background knowledge. If you want your name removed from this list just tell me.

Because we both and the aeronautical world know that it isn't completely random. There are uncertainties and tolerances but we are sure that there is no magic island of low lift to drag somewhere beyond the critical alpha and that stalled (and unrecovered) airliner quickly succumbs to gravity.
How true. The more accuracy is necessary when talking about causes and omissions which lead to gravity winning the game. Your 12 words above lack this accuracy badly and your followup explanation is light footed, as might be mine per chance as well. BEA and airbus should be able to explain it better than we both or other PPRUNīers ever could, but until now they didnīt. As mentioned, BEA saw a lost case early, which does not say, that i agree on that statement. Some well expierienced aircrews might have been able to recover this aircraft omitting the fact, that they might have used their expierience not to get in a situation like that beforehand.

Clandestino
We have also repeatedly seen PPRuNers twisting the facts to suit their theory and then accusing others of doing it. Yawn.
Feel free to tell me when i did or do intentionally or deliberately twist facts. I canīt see any of it in those two posts or in any other i made until now, and there is no reason to be upset at me and twisting the posts to personal difference matter. Your last statement together with "YAWN" shows, that you are not willing to discuss the matter openly and instead revert to discredit not only my post but even my person with belonging to a group twisting facts for own benefit. I know, there is no fair world.

Last edited by RetiredF4; 15th Oct 2012 at 19:57.
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Old 15th Oct 2012, 19:56
  #248 (permalink)  
 
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Originally Posted by RetiredF4
As mentioned, BEA saw a lost case early, which does not say, that i agree on that statement. Some well expierienced aircrews might have been able to recover this aircraft ...
Isn't that exactly what BEA's HF group are saying when they write: "Only an extremely purposeful crew with a good comprehension of the situation ..." ?
Final report 2.1.3.5 End of the flight
At about 2 h 12, descending though FL 315, the aeroplane’s angle of attack was established around an average value of about 40 degrees. Only an extremely purposeful crew with a good comprehension of the situation could have carried out a manoeuvre that would have made it possible to perhaps recover control of the aeroplane. In fact, the crew had almost completely lost control of the situation.

Last edited by HazelNuts39; 15th Oct 2012 at 19:57.
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Old 15th Oct 2012, 19:58
  #249 (permalink)  
 
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@HazelNuts39
Thank you for quoting.

However, the human factors group section is 1.16.8 page 101-106.
The quoted statements are from sub-para 2.1.3.5 "end of flight" out of of the " 2. Analysis section. Even if it would have been influenced by the HF-group it is non the less in agreement of the whole investigation body "BEA".

Last edited by RetiredF4; 15th Oct 2012 at 20:14.
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Old 15th Oct 2012, 20:22
  #250 (permalink)  
 
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Originally Posted by RetiredF4
However, the human factors group section is 1.16.8 page 101-106.
Just to be pedantic:
1.16.8 ... the work of the Human Factors group served as the basis to draw up the accident scenario as detailed in part 2.1 of this report.

2.1 Accident Scenario
This part is mainly based on the results of the work of the Human Factors group, whose approach is described in paragraph 1.16.8.

Last edited by HazelNuts39; 15th Oct 2012 at 20:36.
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Old 15th Oct 2012, 21:00
  #251 (permalink)  
 
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@HN39
not pedantic at all.
My point was based on the impression, that some posters tend to disqualify the HF work as not substantial enough and as a sideline view of the investigation. In the way BEA reserves a paragraph for the Work of the HF group (1.16.8) and then incorporates the findings of the HF group in the part 2.Analysis highlights not only the work of the HF group, but makes it a main part in the analysis and findings of investigation.
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Old 15th Oct 2012, 21:55
  #252 (permalink)  
 
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Originally Posted by RetiredF4
some posters tend to disqualify the HF work
The HF group are making many valuable observations that are well worth considering. They do not always make a clear distinction between fact and opinion or speculation and should be read as such. I'm not disqualifying their work but tend to distinguish their observations from the 'findings' of the investigation.
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Old 15th Oct 2012, 21:57
  #253 (permalink)  
 
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Interesting discussion.

You not need to look at the other control column or sidestick to know what is happening to your aircraft, when all the information you need is in front of you. And do a X-check with STBY and/or the other pilots instruments. That is the best way to go.
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Old 15th Oct 2012, 22:11
  #254 (permalink)  
 
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Originally Posted by 737Jock
As a flightcrew we ARE the originator. Flying is not an individual game on airliners, we operate the aircraft as a crew not as individual pilots.
Correct, applied to situational awareness and decision making! when it comes to manipulating the flight controls, only one pilot can do it at the time be it left, right, or auto. Otherwise, it turns out ugly on any airliner. I know professional pilots know this but seems we have to bring down the discussion to the level of interested amateurs.

Originally Posted by 737Jockl
I thought there was no such thing as feedback on modern airliners...
You were wrong but let me correct your misconception for you: there is a lot of feedback on any airliner it's just that most of them use powered controls so there is one specific type lacking: controls feedback. Example of the exemption is ATR; it is modern airliner and it has it.

Originally Posted by 737Jock
You can't do both things at the same time unless you have a HUD
Bingo! Scrap the rest of the assumption.

Originally Posted by 737Jock
I never stated that hard landings don't occur on aircraft with interconnected yokes. Most hard landings result from unstable approaches in fact most landing incidents and accidents result from unstable approaches.
Well, glad we have cleared up that no flight controls architecture is involved so far.

This however does not mean that the airbus FBW does not play a role, and not every firm landing that undergoes subsequent maintenance inspection is an incident or accident

But why o why would the AAIB write this?:

Quote:
Use of the takeover pushbutton is not instinctive and previous accidents investigated by the AAIB have revealed instances involving Airbus fly-by-wire aircraft types where non-handling pilots have failed to use the button when making control inputs to correct those of the handling pilot. The Civil Aviation Authority also has other evidence where failure to use the takeover button has caused additional aircraft control problems.
The Airbus fly-by-wire aircraft types are unique in commercial aviation in that it is not possible for one pilot to feel what the other pilot is doing with his or her sidestick. In brief, there is no force or position feedback from one sidestick to the other and in the air, there is no stick position information on the flight instrument displays. Consequently there is no practical method of 'assisting' the handling pilot by making a control input on the other sidestick, particularly if the handling pilot is also moving his or her sidestick at the time. The result of two sidestick inputs is a blend of both and, since the aircraft's reaction is inconsistent with its normal 'manoeuvre demand' response, the resultant response cues may seem abnormal for both pilots which in turn, can provoke more extreme sidestick inputs.

Oh did you see that even the AAIB call it force or position feedback from one sidestick to the other. Could you please contact them that their use of the word feedback is inappropriate.
Originally Posted by CONFiture
The Airbus sidestisk philosophy suppresses valuable information to a PNF.
This is a reality documented not only here on PPRuNe, but also by the AAIB … Are they unscrupulous or sciolists as well ?
Dear CONFiture, 737Jock and the rest of the PPRuNe.

First, let us concentrate on the role of the AAIB
Originally Posted by Keith Conradi, the chief inspector
The purpose of the AAIB is:

To improve aviation safety by determining the causes of air accidents and serious incidents and making safety recommendations intended to prevent recurrence
...It is not to apportion blame or liability.
To this end AAIB investigates accidents and incidents and publishes reports that include factual informations, analysis and recommendations. Their reports are made public so anyone interested in improving their chances of survival can read them, learn something and avoid falling the footsteps of their colleagues and falling into the same traps. There is always the risk that unscrupulous might use information included for their ends, but if we want to have the information be made available to everyone that can really use it, we have to live with that risk.

One simple method to push agenda, much used by politicians and marketing, is to pull out part of the text out of context and then build theory around it that contradicts the whole text. Examples we have been provided are taken from this AAIB report: Airbus A320, C-GDTK, 16 June 2003, Bristol. If we read just the quote we have been provided, we might be easily lead to believe that AAIB is really concerned about having not interconnected sidesticks. If it were really so, then for sure they would recommend change in flight controls, the one that was many a time requested here on PPRuNe.

There is no such recommendation.

AAIB is mostly concerned with training provided by Skyservice to their pilots. They say pushing and holding priority button is not instinctive but they don't recommend redesign it, they recommend training pilots to use it. I can personally confirm that this was implemented in my training syllabus as of Jan 2007.

Also, BEA has written: "It is worth noting that the inputs applied to a sidestick by one pilot cannot be observed easily by the other one." That's about it. No further reference to it or recommendations based on it were made.

Case that accident investigating agencies have misgivings about Airbus flight controls architecture looks very slim, eh?

Originally Posted by Retired F4
This last part of your post is not only wrong, it might be deadly wrong
I have already acknowledged I was wrong. Twice. Third time: I was wrong, as proven by the stick positions recorded on the DFDR.

Originally Posted by Retired F4
My conclusion stands, that there are lots of other factors than elevator position or SS position alone for the four consecutive nose drops of AF447 in the referenced stalled situation mentioned by yourself. Whats wrong with that?
Nothing, you are pretty correct so far.

However, two of them happened after elevators went out of full nose-up, two after reducing the power. I can see a pattern here, not:
Originally Posted by Retired F4
All those factors interact together and produce a near random output
Originally Posted by Retired F4
Your last statement together with "YAWN" shows, that you are not willing to discuss the matter openly and instead revert to discredit not only my post but even my person with belonging to a group twisting facts for own benefit.
It is not personal, therefore: it is not about me, it is not about you, it is not about the trolls, it is not about anybody.

It is about the facts, specifically about twisting of them. I don't care if it's intentional or otherwise, I am just interested in having them straight.
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Old 15th Oct 2012, 22:21
  #255 (permalink)  
 
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Howdy Fropilot...

Yes, it is not necessary to take note of the flying pilot's stick work. It is also not possible, so would appear to be inarguable as well. per BEA notation.

The MP does just that "Here, and Here, and here...." "The three say we go up, so go down," etc.

Captain, "Climb please..." PF, "But I have held back the stick this while..." etc.

So we know the circumstances on the flight deck, without question:

1. Cross checks were done, and

2. Both non-handling pilots could not see the controls being operated by the PF.

So,

3. It was not enough that cross checks were both available and utilised, and

4. Had the controls been visible, a separate solution could have begun, and

5. The solution, being unavailable BY DESIGN, was prevented, and the a/c crashed

Because the stick was not visible? That case can be made, and I make it. BEA go so far as to bracket the above exchange between Pilot Flying, and the Captain.

So it is established that BEA think,

1. It is important to note stick is not visible, and.

2. The Captain cannot see it, so

3. The Captain offers the solution, "Let's climb," and the PF says essentially, "I have been, all this while.

So you need to ask yourself, if the Captain found out early enough that the RH stick was pulled back, would he have figured out the attitude was arrived at, and held, by command, not some unknown and perplexing development?

The three pilots and 225 others were dropping at 180 miles an hour, one assumes a sense of urgency on the flight deck......

You say instruments were or should have been sufficient, I say they were not.

What would the Captain have said? Another comment missing on the CVR.....

I was shown what happens to an a/c when back stick is held in STALL, before I had twenty hours. Did this Captain forget? Never knew?

For the record, what is addressed in this post is what the BEA reported, visibility of side stick from each position is not available. I have built on that data to further a theory, do I need to look on the bottom of the page? Shall I suggest another word? Solypsis?

Last edited by Lyman; 15th Oct 2012 at 22:33.
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Old 15th Oct 2012, 22:41
  #256 (permalink)  
 
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Looking again at the graphs of parameters in Appendix 3 and following up from 02.12, the power was reduced at much the same time as Pitch was reduced. The V/S was closer to zero for the few seconds, until power was restored to TOGA.
I suppose that this is the "Underslung engine" effect, for want of a better expression. ( The A/T had been off/ deselected, IIRC, so this may have been a manual reselection.)
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Old 15th Oct 2012, 22:45
  #257 (permalink)  
 
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I knew what holding full back on the stick in a stall would do in under 3 hrs before soloing at 5 hrs.

This captain knew it too obviously but not seeing the position of the PF's SS and entering the cockpit after they had totally lost control holding full back for so long saw a situation he had never encountered in his flying career.
If he had been in his seat when they lost airspeed he would have never let this happen with his experience.
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Old 15th Oct 2012, 23:04
  #258 (permalink)  
 
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No question.
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Old 16th Oct 2012, 00:31
  #259 (permalink)  
 
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Originally Posted by Clandestino
Examples we have been provided are taken from this AAIB report: Airbus A320, C-GDTK, 16 June 2003, Bristol. If we read just the quote we have been provided, we might be easily lead to believe that AAIB is really concerned about having not interconnected sidesticks. If it were really so, then for sure they would recommend change in flight controls, the one that was many a time requested here on PPRuNe.
You lead to believe whatever you want to – It is your call.
But what the AAIB writes is not different from what I do :
  • The Airbus fly-by-wire aircraft types are unique in commercial aviation in that it is not possible for one pilot to feel what the other pilot is doing with his or her sidestick.
  • The Airbus sidestisk philosophy suppresses valuable information to a PNF.
You’re not ready to accept such comments are made – It is not clear why – But it is your call.
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Old 16th Oct 2012, 07:28
  #260 (permalink)  
 
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If it were really so, then for sure they would recommend change in flight controls
You’re not ready to accept such comments are made – It is not clear why
suspect No.1 for both: AB$
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