PPRuNe Forums - View Single Post - Airbus takes pilots back to basics with the A350
Old 14th Oct 2012, 21:52
  #236 (permalink)  
Join Date: Feb 2005
Location: Correr es mi destino por no llevar papel
Posts: 1,417
Well, a week ago I'd put some of the things written in this thread into "you just can't make this stuff up". Once again, I was proven wrong.

I have repeatedly warned about the hilarious theories that are inevitably put forward when someone without the basic grasp of the theory of flight tries to go into details of sophisticated flight control system. Now we have moved a couple of notches up with debaters unable to understand simple general terms such as "feedback".

Originally Posted by 737Jock
Whatever Clandestino... Thank god you know it better than the dictionary.
Nope. I know it as well as dictionary and most of the world. No better, no worse.

Originally Posted by 737Jock
If I put my hand on moving thrust levers, I am getting tactile feedback on what the autothrottle is doing.
If I put my hand on a yoke/stick that moves, I am getting tactile feedback om what the autopilot/my colleague is doing.
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!

Control feedback that was so much discussed with so many misconceptions here involves feeling of the resistance of the flight controls as yoke or stick is moved. As the aeroplanes grew bigger and were operated across the wider speed range, having aerodynamically balanced manually operated flight controls become impractical so we switched to power (that is hydraulic) operated controls. There is no any feedback in them as yoke doesn't move the controls any more but a block of hydraulic valves and 3000psi actuators don't care much if aeroplane is standing still or flying around at 400KEAS, they will move the controls anyway. So in order to prevent pilots from whamming their yokes and overstressing the airframes at high speeds, synthetic pitch feel or artificial feedback had to be introduced that simulates for the pilot the feeling of aeroplane as if it had classic C-172 like controls.

There is no control feedback on most of todays airliners, last one I've flown with it was ATR-42. What feels like it is just synthetic pitch feel, which is heavily dependent on the proper working of air data computers. Objection that synthetic pitch feel feels like classic controls so all the discussion about it is purely academic is valid up to (very low) point. If one berates Airbus for not having feedback while Boeing does, this point has been passed.

Originally Posted by Gretchenfrage
Airbus is wasting their money.
Not in the real world.

Originally Posted by gretchenfrage
Tactile feedback is anything coming back in a sensory mode through feel.
It has nothing to do with physically moving anything.
It is using a sensory input to a human being other than visual or aural.
No it is not. Your definition lacks the essential part of the feedback: return information.

Originally Posted by Gretchenfrage
You should get more human interaction on all levels, especially with a partner, maybe you will get it one day ......
Why are you resorting to personal attacks? Quite a nice discussion we are having here, eh?

Originally Posted by bubbers44
I had an FO, ex B52, who always said he had moderate turbulence on short final for the last several hundred feet of his flights with me. I could feel his PIO's on my yoke but said nothing. Once even the tower commented on our unstable approach. I call this tactile feedback in a Boeing 757.
Originator is your alleged FO, receiver is you, where is the return of information? Sorry, this isn't feedback either.

Originally Posted by bubbers44
I also wouldn't want to be without the tactile feedback Boeing gives.
Which one? 247 certainly, 737NG certainly not.

Originally Posted by Gretchenfrage
Plus the feature to override pitch/bank limit prot with increased force, when necessary.
(To enable the LHR stunt)
In which LHR stunt were 67° bank or -15/+30 pitch exceeded?

Originally Posted by Retired F4
Thatīs the point. A stick release would have changed nothing, as the trajectory would have been maintained by the C* law. We discussed that to the end already.
Well, thank you again for pointing it out.

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. See the page 6 of the Annex 3 linked below:
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.
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.
So you are making a case around my one imprecision that I thanked you for refuting. Be my guest. As for BEA seeing the lost case, it is obvious that CM2 chased the aeroplane into stall and maintained her there so there was no chance he would perform the difficult recovery.

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.
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?

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.

We have also repeatedly seen PPRuNers twisting the facts to suit their theory and then accusing others of doing it. Yawn.

Originally Posted by 737jock
There have been plenty of hard landing incidents that could have been prevented by interconnected sidesticks.
There are plenty of hard landings that were not. If you are really interested in prevention of hard landings and not into some politicking based on unsubstiated opinions being passed as fact, read this. 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.

Originally Posted by 737jock
There are various reasons why 2 pilots can be on the controls during normal line operations, not just manual reversion.
Which would they be?

Originally Posted by Lyman
"But I HAVE been pulling back, all the while".... no shit. And people defend this architecture?
So unprotected Airbus stalls if pulled hard. As does anything else. Why are some PPRuNers so shocked with basic aerodynamics?

Originally Posted by Lyman
Bonin did not have a clue what his controls were doing to the airplane.
Correct. It was CM2 that had no idea. No indication that ample indications were not available that would help someone more self-possessed to realize what he was doing to aeroplane.

Originally Posted by Lyman
What are we missing?
Some of us discussing here are missing the basic knowledge of how aeroplane flies and how airliner crew functions (or at least how it ought to), however, I must stress that airing completely hare-brained theories is absolutely against no RoE here, as long as it is made in courteous manner.

Originally Posted by 737jock
Clearly the current airbus FBW logic has an impact on Situational Awareness. And the biggest impact on safety is Situational Awareness. Period.
Are you concerned enough to make your viewpoint available to EASA or at least your airline's safety department? They don't read PPRuNe.

Originally Posted by 737Jock
There is lots and lots more scientific background on how people process information. There is about 20 years of incident and accident data.
Is there anything supporting the notion that Airbus FBW is step backward from "traditional" controls except laments on anonymous forums and in sensationalist media?

Originally Posted by 737jock
So to be able to feel the input enables the pilot monitoring to look outside for visual cues and judge if the input is sufficient.
Airbus pilots a) feel the input b) make thousands of flights daily that end up in successful flare and landing c) provided your notions are true, deserve better pay for deploying higher skills than their Boeing counterparts to safely land the more difficult aeroplane.

Originally Posted by 737Jock
Any hard landing incident or even a long landing/ soft bounce you will never hear about seems to be of no value to you.
Well, I guess I'll just repost the link: FSF digest Aug 2004: Avoiding the hard landings.

Originally Posted by 737Jock
Maybe that LH airbus should not have started the approach because of crosswind limits, but that doesn't mean that the control system did not have any impact on the incident.
Operating outside limits invalidates CofA but then pilots know that. How about using wrong roll input while decrabbing in over-limit crosswind and bending wingtip fence as result? Scandalous!

Originally Posted by 737Jock
Some landing incidents on airbus aircraft:
Some landing incidents on Airbus, Lockheed, Boeing, Embraer &tc. Page 17 onward.

Originally Posted by Gretchenfrage
The controversy would cease!
There is not much controversy outside PPRuNe.

Originally Posted by donpizmeov
I don't rely on where I feel the flight controls to be positioned.
Which is, incidentally, the correct way on any aeroplane except basic trainers.

Originally Posted by donpizmeov
Pilots can now talk the talk, but have no idea what it means.
Which is far, far greater problem than control design.

Originally Posted by Gretchenfrage
Yes, by my first flight instructor on the J3!!
It is important to be able to tell the difference between Airbus and Cub.

Originally Posted by CONFiture
Is it a serious question ?
Of course it is. Maybe even too serious for this debate as the answer is: "No".

Originally Posted by CONFiture
It is nice to see now guys coming up and testify through their own experience how the Airbus sidestisk philosophy deprives a crew from very valuable information.
Red warning at the bottom of this page takes away a lot of nicety from it, eh?

Originally Posted by 737Jock
How do u know how much input you need to make to get the desired effect?
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.

Originally Posted by 737Jock
Seriously this place is flooded by wannabee's who haven't got a clue.
I would be extremely concerned if it were otherwise.

Originally Posted by Lyman
Yes, TRIM reduces drag, it is not meant to reduce arm fatigue that results from actually deflecting the elevators, that span a five story building's height.
Trim relieves force on the stick, elevators so large are hydraulically powered. I am tempted to say that now I've read it all but I am pretty sure proving me wrong would be just matter of minutes.

Originally Posted by Lyman
From this recent accident, it is clear the pilot is unaware of his attitude, and also his increasing altitude
Not any pilot. Two very specific pilots.

Originally Posted by Lyman
A screen is a LIE, it has no depth, of position, or vector.
Which seemingly doesn't prevent thousands of flight every day in EFIS aeroplanes from being performed successfully.

Originally Posted by shy talk
Maybe someone would care to explain the BENEFIT of having un-linked controls?
Personally, I found posts by people with noth much clue about aviation in general and Airbus FBW in particular, about how it is bad or outright dangerous pretty entertaining and that's benefit enough for me.

Had been flying them for two years. Found them satisfactory. Earned my keep. Moved on. Wouldn't let the good T&C post pass me by if it involves flying them again or put up with bad T&C just to get back on Airbus.

Originally Posted by shy talk
Its utterly unconceivable that that a/c would have fallen as it did, with a pilot holding a yoke right back in his belly.
No need to imagine anything. Other yoked aeroplanes did just that.

Originally Posted by shy talk
It's as simple as that.
Might be simple but is false nevertheless.

Originally Posted by Lyman
.they had in their minds that the stick was not doing what they input.
Possibly, but they were wrong. Now if it ever gets proven (almost no chance), would those people slandering the Airbus FBW be proud of their feat, namely putting uncertainty and fear in the minds of Airbus pilots?

Originally Posted by CONFiture
This is how a PF analyses but why depriving a Pilot Monitoring from such analysis as he cannot know anything about the inputs made by the PF on the Airbus ?
Because outside PPRuNe not much relevance is attached to it.

Originally Posted by Lyman
"That is not correct. The sidestick which was predominantly nose-up until 02:10:24 was predominantly nose-down between 02:10:26 and 02:10:40"

Yet the a/c continued up and up, the flight path was smooth as was trend, Vs.
Pushing the stick on Airbus will reduce the pitch, it will not automatically make the aeroplane descend.

Originally Posted by Lyman
If only PF and his MP could have seen the merged lines on that swell graph.
If they paid attention to instruments or knew what they were supposed to do, there would be no report, thence no graph.
Originally Posted by AAIGUY
The fact is the crew are less pilots, and more systems operators on the Airbus.
Nope. It's your opinion. If you want it to be fact, please lend it some verifiable support.

Originally Posted by Lyman
flying pilot must rely on instruments alone to negotiate the a/c attitude.
That's how it is done in the real world. It tends to give predictable and safe results.

Originally Posted by Lyman
It strikes me that is entirely appropriate; it is not the duty of the manufacturer or the airline to teach ab initio, only to familiarize the transitioning pilot with the platform.
It strikes you so because you misunderstand what was written: starting type rating in direct law without FMGS is familiarization with the basic platform without any bells and whistles. Boy, it does fly nicely.

Originally Posted by Lyman
Airbus, at least their marketing, are in the weeds. There are some design flaws that are being disguised as shortcomings of pilot training, it is a condescending subterfuge, imo.
In the real world, outside of the PPRuNe, not true.
Clandestino is offline