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76794p
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Why Did Airbus Eliminate The Yoke?

Wed Dec 10, 2014 10:54 pm

I have noticed that the A300 and A310 have yokes instead of side-sticks. Why did Airbus replace yokes with side-sticks on every model after the A300 and the A310?
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AirPacific747
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RE: Why Did Airbus Eliminate The Yoke?

Wed Dec 10, 2014 11:06 pm

Because a yoke isn't needed after you have FBW technology in the aircraft. And FBW reduces the weight since less mechanical wiring is required and it also allows for flight envelope protections plus it frees up a lot of space in the cockpit that could be utilised better with a tray table for example which I find very convenient when I'm at work  

Also according to Airbus, the side stick allows for a more precise manoeuvring of the aircraft. So the question should rather be: Why didn't Boeing eliminate the yoke yet?
 
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Stitch
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RE: Why Did Airbus Eliminate The Yoke?

Wed Dec 10, 2014 11:07 pm

Quoting AirPacific747 (Reply 1):
So the question should rather be: Why didn't Boeing eliminate the yoke yet?


There is a discussion about that at Unnecessary 787 Weight (by VC-10 Nov 27 2014 in Tech Ops)

[Edited 2014-12-10 15:09:09]
 
airxliban
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RE: Why Did Airbus Eliminate The Yoke?

Wed Dec 10, 2014 11:09 pm

Another question would be why Airbus didn't feel the need to cross link the side sticks, thereby providing a visual cue to monitoring pilot as to what control input the flying pilot is applying
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Chaostheory
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RE: Why Did Airbus Eliminate The Yoke?

Wed Dec 10, 2014 11:32 pm

Quoting Airxliban (Reply 3):
Another question would be why Airbus didn't feel the need to cross link the side sticks, thereby providing a visual cue to monitoring pilot as to what control input the flying pilot is applying

When FlightGlobal was a reputable aviation magazine (once upon a time), it extensively covered the A320 development and EIS.

It would be well worth trawling through the archive section of FG where I have no doubt your questions will be answered.
 
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 12:57 am

Quoting 76794p (Thread starter):
Why Did Airbus Eliminate The Yoke? 

Could it be because it would have been on the way of the pilots' TV tray?

[Edited 2014-12-10 17:04:02]
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prebennorholm
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 2:13 am

Quoting 76794p (Thread starter):
Why did Airbus replace yokes with side-sticks on every model after the A300 and the A310?

It is equally relevant to ask, why did aircraft manufacturers introduce yokes?

Answer: Because the yoke offers perfect ergonomics when muscle power has to be applied. It would have been hard to fly for instance a Convair B-24 Liberator bomber with unpowered sidestick control.

Sidesticks are nothing new. The very first plane, lifting me off the ground, was designed in 1939, and had sidestick control. An SAI (Skandinavisk Aero Industri) KZ-3, a small two seat side-by-side plane.

It is opposite the current Airbus system, right hand for left seat and vs. In fact it has only one stick, which is Y-shaped, giving a handle to each pilot.

Fully loaded it is just 1400 lbs, and with a 90 HP engine the controls need little muscle power. So the sidestick control is just perfect.

Many still fly today, even if production ended 63 years ago.

That was just the oldest sidestick plane, I have been on. Sure it was nothing new in 1939.

It's nothing special for aircrafts. Ages ago large ships had very large control wheels, and at least in strong wind there were often more than one man hauling it. Modern cruise ships of course go 99% on autopilot, but for maneuvering in harbors a stick gives commands to the control computer.
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LAX772LR
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 2:53 am

Because Boeing boys still have something between their legs!  

...I kid, I kid.

But seriously:

Quoting Airxliban (Reply 3):
Another question would be why Airbus didn't feel the need to cross link the side sticks, thereby providing a visual cue to monitoring pilot as to what control input the flying pilot is applying

        
One could conceivably make the argument that such a feature might've saved AF447.  
I myself, suspect a more prosaic motive... ~Thranduil
 
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 3:07 am

Quoting AirPacific747 (Reply 1):
and it also allows for flight envelope protections

The 777 and 787 both have flight envelope protections (over rideable) and the last I checked they still have yokes....coupled no less fancy that.
 
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 7:12 am

I think it goes to philosophy. Airbus's philosophy seems to be that they want to do everything they can to prevent the pilot from making a mistake (and since the vast majority of crashes are caused by pilot error there certainly is merit in this approach). Hence the flight envelope protection that cannot be easily overridden. They also believe that tactile feedback is unnecessary, and with that in mind a sidestick is so much lighter, easier to install and maintain, and much less in the way than a yoke. It reminds me of the old story about the cockpit crew of the future; it will consist of a pilot and a dog. The pilot's job is to feed the dog, and the dog's job is to bite the pilot if he touches anything. Boeing's philosophy is that programmers cannot anticipate everything that can happen, and therefore the pilot must have ultimate authority over everything. They view automation as an assist to the pilot, not something that will take over from him. I much prefer Boeing's approach, but in fairness I must say that the record does not prove that one is better than the other. One can argue that AF447 would have been less likely in a Boeing, but you can also argue that the Asiana crash would have been less likely in an Airbus. I think the record is about even for the crashes that would have been less likely in the other manufacturer's plane. The point of it is that both of them have achieved superb safety records.
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Starlionblue
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 7:31 am

Quoting LAX772LR (Reply 7):
Quoting Airxliban (Reply 3):
Another question would be why Airbus didn't feel the need to cross link the side sticks, thereby providing a visual cue to monitoring pilot as to what control input the flying pilot is applying

        
One could conceivably make the argument that such a feature might've saved AF447

And one would thus open the usual can of worms. 
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mmo
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 7:40 am

Quoting LAX772LR (Reply 7):
One could conceivably make the argument that such a feature might've saved AF447.

I'm confused.....why would it have made any difference? The incident had nothing to do with the sidestick..... To be honest, it was basic airmanship that was the root cause.
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Starlionblue
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 7:50 am

Quoting mmo (Reply 11):

Quoting LAX772LR (Reply 7):
One could conceivably make the argument that such a feature might've saved AF447.

I'm confused.....why would it have made any difference? The incident had nothing to do with the sidestick..... To be honest, it was basic airmanship that was the root cause.

CAN OF WORMS!!! 

I agree that it was basic airmanship, but the argument is that if the other pilot had actually seen the nose up stick inputs, he would have acted (more quickly) to correct this.
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TheSonntag
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 10:39 am

Quoting SEPilot (Reply 9):
One can argue that AF447 would have been less likely in a Boeing, but you can also argue that the Asiana crash would have been less likely in an Airbus.

There are indeed a few crashes since the introduction of FBW where the interaction of the pilot with the fbw could have contributed to the accident.

Still, the numbers of accidents for all Airbus FBW planes and the B777 combined are much safer than everything else designed before that era, or even worse, the MD-11. So the system obviously works, and the Qantas A380 incident shows that airbus planes can be landed even in case of severe technical problems.
 
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 12:44 pm

Quoting Airxliban (Reply 3):
Another question would be why Airbus didn't feel the need to cross link the side sticks, thereby providing a visual cue to monitoring pilot as to what control input the flying pilot is applying

Quite some time ago I've heard that the reason was, that back then, when it has been developed, it just wasn't possible to design and certify that feature. 30 years ago, computing power was way less available than today.
Introducing force feedback in the Eurofighter was a huge deal, afaIk.
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mmo
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 1:17 pm

Quoting Starlionblue (Reply 12):
I agree that it was basic airmanship, but the argument is that if the other pilot had actually seen the nose up stick inputs, he would have acted (more quickly) to correct this.

I really don't want to open a can of worms, but having flown the 320, you can tell what the other pilot is doing by turning your head! Unless the PNF had his head-down and immobile, I still don't see the point of the comment I referenced.
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Starlionblue
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 1:27 pm

Quoting mmo (Reply 15):

Quoting Starlionblue (Reply 12):
I agree that it was basic airmanship, but the argument is that if the other pilot had actually seen the nose up stick inputs, he would have acted (more quickly) to correct this.

I really don't want to open a can of worms, but having flown the 320, you can tell what the other pilot is doing by turning your head! Unless the PNF had his head-down and immobile, I still don't see the point of the comment I referenced.

I'm saying that was "the argument". I'm not saying it is a valid one. 
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hivue
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 3:26 pm

Quoting Airxliban (Reply 3):
Another question would be why Airbus didn't feel the need to cross link the side sticks, thereby providing a visual cue to monitoring pilot as to what control input the flying pilot is applying

Because sticks/yokes are not flight instruments. Pilots should not make their judgments regarding how the airplane is flying by consulting stick/yoke behavior.

Having said that, there was a thread a few months ago where a pilot -- from Turkey I believe and I think a training pilot -- who said one thing he missed going from B to AB was not being able to feel what a newbie FO was doing with the stick.
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Pihero
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 4:52 pm

THE red herring that gets into the (A.) net every other month...
... and always the same arguments.
1/- The sidestick controller was designed by Airbus as the means to interface with the aircraft behaviour. It was made possible because of the electronic flight controls... and could have been 2 cm tall...without any change in accuracy and *feel* of the aircraft.
It was just a matter of staying with the average pilot muscle memory that its size was chosen.

2/- It has nothing to do with hard or soft limits to the flight envelope. It was designed to give a pilot an intuitive control / feedback loop in maneuvering the airplane. That aspect is proven by the very fast adaptation to the flying characteristics of the family by a pilot new to the stick.

3/- Its design took some time - longer than most people would think - to be frozen to the model we now see : For instance, Airbus thought of a force-based priority logic ( the one who actions the stick the stronger will take control )... another example is the push-to-talk button which was placed on top of the stick, alongside the AP disconnect button and is now a trigger...
The final solution was - is - the priority logic, with aural and visual warnings and algaebraically summed angles of controls.

4/- The final solution is in my opinion a bonus : we revert to basic understanding of airmanship and CRM : only one pîlot flies the airplane. A dual input is recorded and is generally cause for the chief pilot asking questions to the crew.The second can take over at any time by locking the other out.

5/- The *visual cue*, *feedback*... etc... are plain silly and on the verge of intellectual dishonesty : One cannot base one's idea of the flight path on control column / sidestick position . If it were the case, the China Air spiral dive would never have happened .

Question : You're on a 744... The yoke is 60° to the left... Can you tell which way the airplane is turning ?
Answer : No ! it could be the initiation of a left bank or could be a steady right turn.

6/- The right question which should be asked right now is : How long before the yoke disappears from modern cockpits ? As far as I know Airbus, Bombardier, Sukhoi, Dassault, Gulfstream, Embraer... have gone or are going the sidestick path. Left are Boeing and - for the moment - Mitsubishi.
So I'd really like to see a thread about the dying yoke and Daddy's flight deck... because it is really in the order of things.
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airxliban
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 5:45 pm

Quoting hivue (Reply 17):
Quoting Airxliban (Reply 3):
Another question would be why Airbus didn't feel the need to cross link the side sticks, thereby providing a visual cue to monitoring pilot as to what control input the flying pilot is applying

Because sticks/yokes are not flight instruments. Pilots should not make their judgments regarding how the airplane is flying by consulting stick/yoke behavior.
Quoting Pihero (Reply 19):
5/- The *visual cue*, *feedback*... etc... are plain silly and on the verge of intellectual dishonesty : One cannot base one's idea of the flight path on control column / sidestick position . If it were the case, the China Air spiral dive would never have happened .

Appreciate the comments. I know that you would absolutely not want to make decisions on the flight path of airplane by looking at the side stick position. However in a multi crew environment I don't understand why it would be silly for a pilot monitoring to have the ability to check the position of the side stick to figure out what inputs the pilot flying is commanding.

Example - if you're in a stall and the pilot flying has the stick up instead of down, wouldn't that be a cue that you need to intervene? Or if you are in a spin and the aileron positions are showing anything other than neutral, wouldn't you want to have that information?

I know this has been discussed ad nauseum on here. As someone who only flies piston singles and has probably 5% the flight hours of an airline captain, I am still struggling to understand the downside of the visual cue for the side stick, especially given that the rudder pedals in the Airbus cockpit are in fact interconnected.
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sccutler
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 6:39 pm

Quoting mmo (Reply 11):

I'm confused.....why would it have made any difference? The incident had nothing to do with the sidestick..... To be honest, it was basic airmanship that was the root cause.

The accident was not caused by the sidestick, and there is no question that the Airbus flight control philosophy has been proven as a worthwhile contribution to safety. That said, however, it is bordering on silly to suggest that a different physical layout of controls could not have helped prevent the AF447 occurrence - not because the sidestick in any way caused it (it did not), or because the Airbus A330 had any system failures (it all performed precisely as designed), but simply because, with physically linked controls, both pilots can tell- without having to look or meaningfully process the information- what control inputs the other pilot is making.

Quoting mmo (Reply 15):
I really don't want to open a can of worms, but having flown the 320, you can tell what the other pilot is doing by turning your head! Unless the PNF had his head-down and immobile, I still don't see the point of the comment I referenced.

Absolutely correct. Sadly, on AF447, this did not occur. As things became more confusing (why is this beast doing what it is doing, it makes no sense!), as the "helmet fire" burns ever-hotter, the ability to gather in peripheral information (both figuratively and literally) lessens.

It is very easy for pilots to pick apart the things that occurred in the cockpit of a lost aircraft (and, from my observations, non-pilots are even more strident in so doing), but I must compellingly say: I was not there, I don't know how I would have reacted, and anyone who contends "that could never happen to me" is primed for an analogous situation to attack them!

Quoting Pihero (Reply 19):
The *visual cue*, *feedback*... etc... are plain silly and on the verge of intellectual dishonesty : One cannot base one's idea of the flight path on control column / sidestick position

Absolutely correct!

But the issue was not "what is the flight path of the airplane" - they had instruments in front of them to tell them what it was, and those (other than the temporary absence of reliable airspeed information) never failed. The question was, "why in the hell is the airplane doing what it is doing - why are we falling at ten thousand FPM with full power on these magnificent and powerful engines, on this proven and well-maintained airframe?" Had the PNF had a big, honkin' yoke pulled all the way back into his belly, it would have been difficult to ignore. Would it have made a difference? Can't be certain, but it seems improbable.

Of course, knowing all that we know now, the odds of this particular kind of occurrence ever happening again are infinitesimally small - but it is not as if the odds of it happening the day before AF447's ill-fated flight were particularly strong either.

Quoting Pihero (Reply 19):

Question : You're on a 744... The yoke is 60° to the left... Can you tell which way the airplane is turning ?
Answer : No ! it could be the initiation of a left bank or could be a steady right turn.

Yep, all true. Again, we can never say what the airplane is doing based exclusively upon where the yoke is pointing; but it can sure be a useful indicator of why the plane is not behaving as you might expect it to do.
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strfyr51
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 7:12 pm

Quoting SEPilot (Reply 9):
I think it goes to philosophy. Airbus's philosophy seems to be that they want to do everything they can to prevent the pilot from making a mistake (and since the vast majority of crashes are caused by pilot error there certainly is merit in this approach). Hence the flight envelope protection that cannot be easily overridden. They also believe that tactile feedback is unnecessary, and with that in mind a sidestick is so much lighter, easier to install and maintain, and much less in the way than a yoke. It reminds me of the old story about the cockpit crew of the future; it will consist of a pilot and a dog. The pilot's job is to feed the dog, and the dog's job is to bite the pilot if he touches anything. Boeing's philosophy is that programmers cannot anticipate everything that can happen, and therefore the pilot must have ultimate authority over everything. They view automation as an assist to the pilot, not something that will take over from him. I much prefer Boeing's approach, but in fairness I must say that the record does not prove that one is better than the other. One can argue that AF447 would have been less likely in a Boeing, but you can also argue that the Asiana crash would have been less likely in an Airbus. I think the record is about even for the crashes that would have been less likely in the other manufacturer's plane. The point of it is that both of them have achieved superb safety records.

Easier to maintain?? I assume you've troubleshot FAC .FCU, ELAC, FMGC, or SEC problems related to the Side-Stick??
If you had I would NOT say Easier. I've Never had to replace any Yoke in any Boeing. But I Have had to replace and
troubleshoot 10 Side-stick controllers . They're not that hard if you Isolate the problem TO the Side-Stick but You're going to change some VERY Expansive Parts Before you get to the Side Stick and the bill will be in the $100K range in just the
Performance tests alone before you can Return the parts to Stock as "serviceable" With the Yoke? You stich a couple of rig pins in it find out if the transducers are at Null, and replace or Rig them if they Aren't. I would NOT call the Airbus FBW system EASY to troubleshoot.
 
hivue
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 8:35 pm

Quoting Airxliban (Reply 19):
Example - if you're in a stall
Quoting Airxliban (Reply 19):
Or if you are in a spin

Unless done for training these likely will be emergency situations where consulting stick/yoke position would make even less sense than in more benign conditions.
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sccutler
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 8:48 pm

Quoting hivue (Reply 22):

Quoting Airxliban (Reply 19):
Example - if you're in a stall
Quoting Airxliban (Reply 19):
Or if you are in a spin

Unless done for training these likely will be emergency situations where consulting stick/yoke position would make even less sense than in more benign conditions.

And yet, this is where the hapless crew of AF447 found themselves.

In any event, if I found my aircraft doing something which I did not expect, I would most certainly want to know the position of each and every control whose input could affect the aircraft's behavior. I'd gently mention that, in all of the training I have received, and in the documentation for every aircraft I have flown, appropriate control movements and positions are an essential (fundamental) part of the recovery.

EG, in the Bonanza, spin recovery, yoke neutral (roll), sharply forward, opposite rudder. This is pretty standard stuff.
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bueb0g
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 8:48 pm

Quoting ChaosTheory (Reply 4):
When FlightGlobal was a reputable aviation magazine (once upon a time), it extensively covered the A320 development and EIS.

Why is FlightInternational no longer seen as reputable?

Quoting LAX772LR (Reply 7):
One could conceivably make the argument that such a feature might've saved AF447.  

Not really.

Quoting SEPilot (Reply 9):
and therefore the pilot must have ultimate authority over everything

An Airbus crew still has the ultimate authority over the aircraft.

Quoting SEPilot (Reply 9):
They view automation as an assist to the pilot, not something that will take over from him.

Airbus shares this view.

Quoting sccutler (Reply 20):
but simply because, with physically linked controls, both pilots can tell- without having to look or meaningfully process the information- what control inputs the other pilot is making.

Which isn't relevant to AF447, because nobody on the flight deck understood that the aircraft was stalled. If the PM had been saying, 'push the nose down! why are we not recovering?', then there would be an argument. That was not the case, however. The whole crew was disoriented, did not know what was going on and gave contradictory instructions. Indeed, when the PM did actually take control for a short period of time by pressing the sidestick priority, he didn't initiate a stall recovery - he just levelled the wings.

The PM knew the PF was making mostly nose-up inputs, and was just as confused as him as to why this was not generating the desired result.
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sccutler
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 10:18 pm

Quoting bueb0g (Reply 24):
Which isn't relevant to AF447, because nobody on the flight deck understood that the aircraft was stalled.

With respect, while I agree that they did not understand that the aircraft was stalled, we profoundly disagree as to whether a blatant and obvious unusual yoke position (and to be sure, a traditional yoke held fully-aft is both unusual, and very difficult to ignore) might have triggered some response, of some kind.

Again, of course, this remarkably tragic sequence of improbable events is unlikely to reoccur (its original event followed many hundreds of thousands of hours - maybe millions - of safely-conducted operations, and that is not an accident - it is the result of a well-crafted design). So, now, we watch for the next opportunity for pilots to kill a perfectly healthy airplane, behaving exactly as designed, along with its innocent passengers. Flight Level Change misuse, anyone?

Quoting bueb0g (Reply 24):

The PM knew the PF was making mostly nose-up inputs, and was just as confused as him as to why this was not generating the desired result.

No remotely-competent pilot believes that an aircraft can fly normally with the yoke fully-aft; an Airbus with envelope-protection disabled (and they had that information at their disposal) will not. If the PNF knew the the PF was holding the stick full-aft the whole time, then he was suicidal or profoundly incompetent, and there's no reason to believe either applied.

In any event, every change in design of systems and stuff is precipitated by a perceived need; you may be certain that control systems and logic engineers around the world have studied, and will study, this event in great depth, and will strive to do as they can to forestall future analogs.
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AirPacific747
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 10:45 pm

I've now flown with numerous pilots who flew both the 737 and the A320. When I ask them which one they prefer, the conclusion is often the exact same. While the 737 is probably more fun to fly, it is also more demanding. The A320 offers a more comfortable working environment over all, especially given the amount of work pilots do these days. This can partly be contributed to the fact that there is a tray table since we often need to write stuff down or eat food  

With regards to the AF447 accident, well we have also seen Boeing crashes that could be contributed to pilot incompetence which would have been prevented by FBW limitations. For example a 757 that hit the ground in a GPWS maneuver because the pilots forgot to retract the speed brakes. This would not have happened in an Airbus since the computers would have retracted the speed brakes automatically when TOGA is selected.

So no system is completely perfect either way.

[Edited 2014-12-11 14:52:27]
 
Chamonix
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 11:06 pm

 
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KarelXWB
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 11:09 pm

Quoting SEPilot (Reply 9):
One can argue that AF447 would have been less likely in a Boeing

Both AF447 pilots failed to recognize the stall conditioning in the first place, they would had crashed any aircraft.
What we leave behind is not as important as how we've lived.
 
Chamonix
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 11:15 pm

 
Chamonix
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 11:19 pm

 
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KarelXWB
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RE: Why Did Airbus Eliminate The Yoke?

Thu Dec 11, 2014 11:23 pm

Quoting sccutler (Reply 25):
we profoundly disagree as to whether a blatant and obvious unusual yoke position (and to be sure, a traditional yoke held fully-aft is both unusual, and very difficult to ignore) might have triggered some response, of some kind.

Colgan Air Flight 3407 had a yoke, yet both pilots failed to recognize the stall condition. I honestly do not believe a yoke would have saved AF447.
What we leave behind is not as important as how we've lived.
 
PGNCS
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RE: Why Did Airbus Eliminate The Yoke?

Fri Dec 12, 2014 3:02 am

Quoting LAX772LR (Reply 7):
One could conceivably make the argument that such a feature might've saved AF447.

It didn't save Asiana 214.

Quoting Starlionblue (Reply 12):
I agree that it was basic airmanship, but the argument is that if the other pilot had actually seen the nose up stick inputs, he would have acted (more quickly) to correct this.

See above.

Quoting Pihero (Reply 18):
2/- It has nothing to do with hard or soft limits to the flight envelope. It was designed to give a pilot an intuitive control / feedback loop in maneuvering the airplane. That aspect is proven by the very fast adaptation to the flying characteristics of the family by a pilot new to the stick.

Yes, and I can certainly attest that adaptation is quick and, in general, pilots (even those with no prior FBW experience of any kind) quickly grow fond of and confident in the SSC and related Airbus FBW.

Quoting Pihero (Reply 18):

5/- The *visual cue*, *feedback*... etc... are plain silly and on the verge of intellectual dishonesty : One cannot base one's idea of the flight path on control column / sidestick position . If it were the case, the China Air spiral dive would never have happened .

Question : You're on a 744... The yoke is 60° to the left... Can you tell which way the airplane is turning ?
Answer : No ! it could be the initiation of a left bank or could be a steady right turn.

Yes, exactly.

Quoting sccutler (Reply 20):






Quoting mmo (Reply 11):
I'm confused.....why would it have made any difference? The incident had nothing to do with the sidestick..... To be honest, it was basic airmanship that was the root cause.
The accident was not caused by the sidestick, and there is no question that the Airbus flight control philosophy has been proven as a worthwhile contribution to safety. That said, however, it is bordering on silly to suggest that a different physical layout of controls could not have helped prevent the AF447 occurrence - not because the sidestick in any way caused it (it did not), or because the Airbus A330 had any system failures (it all performed precisely as designed), but simply because, with physically linked controls, both pilots can tell- without having to look or meaningfully process the information- what control inputs the other pilot is making.

There is also no reason to believe a yoke would have changed the events. There have been numerous accidents in conventional aircraft with controls held in wholly inappropriate positions. If you don't know you are in a stall there is no need to address a stall. This was an airmanship and disorientation accident, pure and simple.

Quoting sccutler (Reply 20):
Had the PNF had a big, honkin' yoke pulled all the way back into his belly, it would have been difficult to ignore. Would it have made a difference? Can't be certain, but it seems improbable.

Ask the Asiana 214 crew why they found it easy to ignore; you can't ask the Colgan crew sadly.

Quoting sccutler (Reply 25):
With respect, while I agree that they did not understand that the aircraft was stalled, we profoundly disagree as to whether a blatant and obvious unusual yoke position (and to be sure, a traditional yoke held fully-aft is both unusual, and very difficult to ignore) might have triggered some response, of some kind.

It's a wholly non-provable theory.

Quoting AirPacific747 (Reply 26):
I've now flown with numerous pilots who flew both the 737 and the A320. When I ask them which one they prefer, the conclusion is often the exact same. While the 737 is probably more fun to fly, it is also more demanding. The A320 offers a more comfortable working environment over all, especially given the amount of work pilots do these days.

Agreed. I have flown both the A-320 and 737 and would 100% of the time pick the A-320 for any operation I was undertaking.

Quoting AirPacific747 (Reply 26):
With regards to the AF447 accident, well we have also seen Boeing crashes that could be contributed to pilot incompetence which would have been prevented by FBW limitations. For example a 757 that hit the ground in a GPWS maneuver because the pilots forgot to retract the speed brakes. This would not have happened in an Airbus since the computers would have retracted the speed brakes automatically when TOGA is selected.

Fair enough but spoiler retraction with TOGA selection doesn't actually require FBW. The L-1011 did it, for instance. It DOES seem like an obvious design feature that transport category aircraft should have.

Quoting KarelXWB (Reply 31):
Quoting sccutler (Reply 25):we profoundly disagree as to whether a blatant and obvious unusual yoke position (and to be sure, a traditional yoke held fully-aft is both unusual, and very difficult to ignore) might have triggered some response, of some kind.Colgan Air Flight 3407 had a yoke, yet both pilots failed to recognize the stall condition. I honestly do not believe a yoke would have saved AF447.

There's no way to know for sure, of course, but I don't see any reason to believe a yoke would have altered the outcome in any way. Plenty of yoke-equipped aircraft have been involved in stall or low speed accidents over the years.
 
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SEPilot
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RE: Why Did Airbus Eliminate The Yoke?

Fri Dec 12, 2014 7:15 am

Quoting bueb0g (Reply 24):

An Airbus crew still has the ultimate authority over the aircraft.

Not quite; when it is in normal law the aircraft will not let the pilot exceed the limits that the computer has set, from what I understand.

Quoting KarelXWB (Reply 28):
Quoting SEPilot (Reply 9):
One can argue that AF447 would have been less likely in a Boeing

Both AF447 pilots failed to recognize the stall conditioning in the first place, they would had crashed any aircraft.

But the control column held fully back would have given all the other pilots an immediate heads up that this is not right, In the Airbus they could have been unaware of it, and likely were.

Quoting KarelXWB (Reply 31):
Colgan Air Flight 3407 had a yoke, yet both pilots failed to recognize the stall condition. I honestly do not believe a yoke would have saved AF447.

Wasn't the primary problem with Colgan 3407 that they let the airspeed decay? By the time they entered the stall and the yoke was held back the copilot did not have time to react. Also, it would have been a wrestling match and I am sure the captain, being a man while the copilot was a woman, would have won that one.

Quoting PGNCS (Reply 32):
Quoting LAX772LR (Reply 7):
One could conceivably make the argument that such a feature might've saved AF447.

It didn't save Asiana 214.

The problem with Asiana 214 was throttle mismanagement, not holding the yoke back.

Quoting PGNCS (Reply 32):
Airbus since the computers would have retracted the speed brakes automatically when TOGA is selected.

Fair enough but spoiler retraction with TOGA selection doesn't actually require FBW. The L-1011 did it, for instance. It DOES seem like an obvious design feature that transport category aircraft should have.

Didn't Boeing change it after this accident?
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
mmo
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RE: Why Did Airbus Eliminate The Yoke?

Fri Dec 12, 2014 7:53 am

Quoting SEPilot (Reply 33):
But the control column held fully back would have given all the other pilots an immediate heads up that this is not right, In the Airbus they could have been unaware of it, and likely were.

But wouldn't a check of the IVSI have an even better indication of what was going on? Again, I wasn't there, but it seems to me the issue was basic airmanship.

Quoting SEPilot (Reply 33):
The problem with Asiana 214 was throttle mismanagement, not holding the yoke back.

No, the problem was not throttle mismanagement, the problem was not having a working knowledge of what the FMA was telling you. With the thrust levers indication "HOLD", the thrust levers will do just that, sit at idle.....Again, it's an airmanship issue.
If we weren't all crazy we'd all go insane!
 
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KarelXWB
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RE: Why Did Airbus Eliminate The Yoke?

Fri Dec 12, 2014 11:23 am

Quoting SEPilot (Reply 33):
But the control column held fully back would have given all the other pilots an immediate heads up that this is not right

I pretty much doubt that. Both pilots were disorientated and when panic takes over your body, there's little you can do.

Quoting SEPilot (Reply 9):
and therefore the pilot must have ultimate authority over everything.
Quoting SEPilot (Reply 33):
Not quite; when it is in normal law the aircraft will not let the pilot exceed the limits that the computer has set, from what I understand.

The pilot has full control within the performance envelope, but "ultimate authority over everything" is a statement I disagree. In a commercial airliner a pilot should never be able to exceed a certain bank angle, for example. It's not a fighter jet.

[Edited 2014-12-12 03:43:00]
What we leave behind is not as important as how we've lived.
 
Pihero
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RE: Why Did Airbus Eliminate The Yoke?

Fri Dec 12, 2014 11:57 am

Quoting SEPilot (Reply 33):
when it is in normal law the aircraft will not let the pilot exceed the limits that the computer has set, from what I understand.

1/- The *computer* hasn't set anything : The system is programmed so that pilots do not exceed the certification flight envelope.
2/- I haven't seen one single instance of a pilot exceeding the flight envelope in an FBW Boeing since the T7 EIS. Not one.
IMHO, Boeing's increased control loads close to the envelope edges is a not-so-optimal solution . Otherwise they wouldn't have changed the 787 stall / windshear escape characteristics which are basically the Airbus solution since the A320 entered service.

Quoting SEPilot (Reply 33):
the control column held fully back would have given all the other pilots an immediate heads up that this is not right, In the Airbus they could have been unaware of it, and likely were.

That's a vast statement : See TK1951 737 at AMS.
... and especially page 187 of the accident report where PFD was indicating 20° nose up and the yoke was held fully back.

Quoting SEPilot (Reply 33):
Wasn't the primary problem with Colgan 3407 that they let the airspeed decay?

Speed decay --> increased AoA --> increased pitch angle --> yoke full aft... similar situations.

Quoting SEPilot (Reply 33):
The problem with Asiana 214 was throttle mismanagement, not holding the yoke back.

See above. Same situation.

Quoting SEPilot (Reply 33):
Didn't Boeing change it after this accident?

No they did not... and I don't know why. I heard they did not want an excessive pitch change during speedbrake retraction but it sounds to me like "bull as usual".
Contrail designer
 
bueb0g
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RE: Why Did Airbus Eliminate The Yoke?

Fri Dec 12, 2014 12:56 pm

Quoting sccutler (Reply 25):
we profoundly disagree as to whether a blatant and obvious unusual yoke position (and to be sure, a traditional yoke held fully-aft is both unusual, and very difficult to ignore) might have triggered some response, of some kind.

Where does this myth come from that the PF was holding the stick fully aft? He was not! He was making mostly nose-up inputs, but only hit the aft stop around two times - look at the data from the report!

Quoting sccutler (Reply 25):
If the PNF knew the the PF was holding the stick full-aft the whole time, then he was suicidal or profoundly incompetent, and there's no reason to believe either applied.

The PF was not holding the stick full back the whole time. And indeed, several times the PM said to the PF to "go up" - the PM knew the PF was pulling up but, exactly like the PF, did not understand that they were stalled, and as such did not understand why they were not climbing! This was an incredibly confused crew. Slaved controls would have done nothing to save them, because neither of them saw anything wrong with the PF's inputs!

Quoting SEPilot (Reply 33):
Not quite; when it is in normal law the aircraft will not let the pilot exceed the limits that the computer has set, from what I understand.

Limits which no pilot would ever want to willingly exceed. If a pilot is outside of the envelope, it is because he has made a mistake. Hard protections therefore assist the crew by stopping them getting into attitudes they would never want to be, so it's not really to do with pilots having 'full authority'. And whenever an abnormal situation occurs that means the aircraft can no longer, with assurance, determine where those limits should be (i.e air data failure etc) the protections stop. In addition, the crew can always put the aircraft into alternate/normal law themselves, so there is no loss of authority. In an Airbus aircraft, just like every other airliner, the crew are in complete control.

Quoting Pihero (Reply 36):
No they did not... and I don't know why. I heard they did not want an excessive pitch change during speedbrake retraction but it sounds to me like "bull as usual".

Actually I think they did. The 777 and the 787 auto retract with high thrust, and I think there was a fix to 757/767s to introduce this feature there too but don't quote me.
Roger roger, what's our vector, victor?
 
Pihero
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RE: Why Did Airbus Eliminate The Yoke?

Fri Dec 12, 2014 1:41 pm

Quoting bueb0g (Reply 37):
The 777 and the 787 auto retract with high thrust

My T7 FCOM / FCTM doesn't mention any auto-retract with applied thrust.
The windshear procedure clearly states : "Retract Speedbrakes".

I have no info on the 787.

Quoting bueb0g (Reply 37):
I think there was a fix to 757/767s to introduce this feature there too

Never heard of it.
What I know is that this feature is not on the 737 family ( up to the NG).

[Edited 2014-12-12 05:42:23]
Contrail designer
 
mmo
Posts: 2059
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RE: Why Did Airbus Eliminate The Yoke?

Fri Dec 12, 2014 3:13 pm

Quoting bueb0g (Reply 37):
Actually I think they did. The 777 and the 787 auto retract with high thrust, and I think there was a fix to 757/767s to introduce this feature there too but don't quote me.

The 777/787 DO NOT auto-retract inflight. What you do get is an EICAS message (Caution) SPEED BRAKES displayed and an aural indication. On the ground, it's a different story.

From the FCOM.....

Spoiler Speedbrake Operation
The 14 spoiler panels are used as speedbrakes. In the normal mode, when used as
speedbrakes, spoilers 5 and 10 are available as ground speedbrakes only. In the
secondary and direct modes, spoilers 4, 5, 10, and 11 are locked out.
The speedbrake spoilers are controlled by the speedbrake lever located on the
control stand. The speedbrake lever has three marked positions:
• DOWN
• ARMED
UP.
The speedbrake lever can be placed in intermediate positions between ARMED
and UP.
In the ARMED position, the speedbrake lever is driven aft to the UP position
when the landing gear is fully on the ground (not tilted) and the thrust levers are
at idle.
On the ground when either reverse thrust lever is moved to the reverse idle detent,
the speedbrakes automatically extend. The speedbrake lever does not need to be
in the ARMED position. A mechanical link between the speedbrake lever and the
reverse thrust levers raises the speedbrake lever out of the DOWN detent. The
speedbrake lever is then driven aft and the speedbrakes extend. If either thrust
lever is advanced to a takeoff position, the speedbrake lever is driven to the down
position.
Automatic speedbrakes are not available in the secondary and direct modes.
There is no limitation for extension of speedbrakes in a landing configuration
If we weren't all crazy we'd all go insane!
 
sccutler
Posts: 5839
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RE: Why Did Airbus Eliminate The Yoke?

Fri Dec 12, 2014 3:34 pm

Quoting PGNCS (Reply 32):

Quoting sccutler (Reply 25):
With respect, while I agree that they did not understand that the aircraft was stalled, we profoundly disagree as to whether a blatant and obvious unusual yoke position (and to be sure, a traditional yoke held fully-aft is both unusual, and very difficult to ignore) might have triggered some response, of some kind.

It's a wholly non-provable theory.

Quite right - the plane is lost, the pilots and passengers long dead and buried, and the identical combination of circumstances will never occur again. Fortunately, the experience and knowledge gained from this and other occurrences will continue the relentless asymptotic approach to absolute safety. It is comforting to know that engineers schooled in human factors and charged with reviewing incidents such as this one wisely choose to consider every possibility of contributing factors, and every change in design and training which might ease any risks found, rather than discounting, out of hand, any such factors which do not fit their opinion of the facts.

Quoting Pihero (Reply 36):

Quoting SEPilot (Reply 33):
Wasn't the primary problem with Colgan 3407 that they let the airspeed decay?

Speed decay --> increased AoA --> increased pitch angle --> yoke full aft... similar situations.

Of course, they did not have thirty-plus thousand feet of altitude in which to try a correction.

Quoting Pihero (Reply 36):
Quoting SEPilot (Reply 33):
The problem with Asiana 214 was throttle mismanagement, not holding the yoke back.

See above. Same situation.

I think we can see some serious CRM issues in this instance, as well - it appeared that at least one pilot saw the problem developing.
...three miles from BRONS, clear for the ILS one five approach...
 
bueb0g
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RE: Why Did Airbus Eliminate The Yoke?

Fri Dec 12, 2014 5:02 pm

Quoting Pihero (Reply 38):
My T7 FCOM / FCTM doesn't mention any auto-retract with applied thrust.
The windshear procedure clearly states : "Retract Speedbrakes".
Quoting mmo (Reply 39):
The 777/787 DO NOT auto-retract inflight. What you do get is an EICAS message (Caution) SPEED BRAKES displayed and an aural indication. On the ground, it's a different story.

Interesting... Does anybody know Boeing's rationale for not having auto-stow? Is there a situation where you would want high-thrust and spoilers?

Quoting sccutler (Reply 40):
I think we can see some serious CRM issues in this instance, as well - it appeared that at least one pilot saw the problem developing.

Indeed, in the Asiana crash the co-pilot sitting in the jumpseat called out 'airspeed' and 'sinkrate' to the flying pilots, which was ignored or not properly acted upon. AF447 also had some serious CRM problems though, for instance no defined command chain was decided after the commander left the cockpit.
Roger roger, what's our vector, victor?
 
sccutler
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RE: Why Did Airbus Eliminate The Yoke?

Fri Dec 12, 2014 5:51 pm

Quoting bueb0g (Reply 41):
AF447 also had some serious CRM problems though, for instance no defined command chain was decided after the commander left the cockpit.

Yep. Reading the CVR transcript is heartbreaking, because we had two, then three, trained and (presumably) competent pilots, and no one of them could manage to step back from the symptoms and apply basic airmanship. I'd love to say that could never happen to me, but it would be the height of delusion.

We live, we learn. It is very fortunate that the FDR and CVR were ultimately found.
...three miles from BRONS, clear for the ILS one five approach...
 
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Starlionblue
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RE: Why Did Airbus Eliminate The Yoke?

Sat Dec 13, 2014 1:37 am

Quoting sccutler (Reply 40):
Quoting Pihero (Reply 36):

Quoting SEPilot (Reply 33):
Wasn't the primary problem with Colgan 3407 that they let the airspeed decay?

Speed decay --> increased AoA --> increased pitch angle --> yoke full aft... similar situations.

Of course, they did not have thirty-plus thousand feet of altitude in which to try a correction.

Indeed.

On a related note, certainly if you're close to the ground and in an upset the instinct is to pull up. However if you're going to hit the ground anyway it is always better to impact in a wings level attitude than stall, wing-over and crash in some weird attitude. Airbus flight envelope protection ensures that the plane is at least under control even if it is forced to descend. The famous Mulhouse crash is a perfect example. Even after the pilots completely bungled and impact was inevitable, the aircraft stayed wings level instead of stalling close to the ground. This probably saved the lives of the survivors. If the plane had stalled and dipped a wing, all would most likely have perished.

As a result of Golgan and other crashes, nowadays even new PPL students are taught that nose down is the most important thing in stall recovery. Previously there was also a focus on not losing too much altitude but that is now secondary to getting the AoA down and airspeed up. My PPL examiner explained that too many pilots focused too much on not losing altitude, pulling back too soon after recovery and ending up back in a stall.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Chamonix
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RE: Why Did Airbus Eliminate The Yoke?

Sat Dec 13, 2014 2:50 pm

And why no autoretract on Boeing?
 
David L
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RE: Why Did Airbus Eliminate The Yoke?

Sat Dec 13, 2014 4:14 pm

Quoting bueb0g (Reply 37):
Where does this myth come from that the PF was holding the stick fully aft? He was not! He was making mostly nose-up inputs, but only hit the aft stop around two times - look at the data from the report!
Quoting bueb0g (Reply 37):
And indeed, several times the PM said to the PF to "go up" - the PM knew the PF was pulling up but, exactly like the PF, did not understand that they were stalled, and as such did not understand why they were not climbing! This was an incredibly confused crew. Slaved controls would have done nothing to save them, because neither of them saw anything wrong with the PF's inputs!

   Thank you - saved me a lot of typing! These are a couple of myths that just won't go away.
 
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crimsonchin
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RE: Why Did Airbus Eliminate The Yoke?

Sat Dec 13, 2014 8:27 pm

Threads like this make me so happy we have experts on here who fly or are knowledgeable about the darn things. The amount of willful ignorance and misinformation that's spread when any topic about Airbus flight systems comes up is staggering.
 
mmo
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RE: Why Did Airbus Eliminate The Yoke?

Sat Dec 13, 2014 10:01 pm

Quoting bueb0g (Reply 41):
Interesting... Does anybody know Boeing's rationale for not having auto-stow? Is there a situation where you would want high-thrust and spoilers?
Quoting Chamonix (Reply 44):
And why no autoretract on Boeing?

When the 777 was being designed prospective airlines formed a working group to provide input to Boeing. The auto-retract in flight was not mentioned since there was a warning associated with that condition. You will know immediately if you forget to forget to retract them.

As for the yoke vs sidestick again, there was no request or demand for it. So Boeing went with it knew and provided feed back through the yoke. That is why on the 777 you trim for speed and not configuration changes.
If we weren't all crazy we'd all go insane!
 
Pihero
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RE: Why Did Airbus Eliminate The Yoke?

Sun Dec 14, 2014 12:00 am

Quoting Starlionblue (Reply 43):
Quoting SEPilot (Reply 33):
Wasn't the primary problem with Colgan 3407 that they let the airspeed decay?

Speed decay --> increased AoA --> increased pitch angle --> yoke full aft... similar situations.

Of course, they did not have thirty-plus thousand feet of altitude in which to try a correction.

Indeed.

You have to make up your mind : Your statements are a bit contradictory :

Quoting SEPilot (Reply 33):
Both AF447 pilots failed to recognize the stall conditioning in the first place, they would had crashed any aircraft.

But the control column held fully back would have given all the other pilots an immediate heads up that this is not right,

If the "heads up" is so immediate, they should have identified the situation whether at high or low altitude... which they did not.
The China Airlines 006 incident is more of a case : 32000 ft lost... no pilot intervention although the yoke at 23° and still a bank in the opposite side, with a known engine failure...seems that your theory on *obvious cue / heads up / diagnosis....etc...* is not so onvious to me - or that crew... and you could find a lot of other instances in any air accident data base.
Excerpts :
"Although the roll angle of the airplane remained fairly constant at about 2.6° to 3.5° left-wing-down, the left-wing-down deflection of the control wheel continued to increase as the indicated airspeed decreased, and, by 1013:43 the deflection had increased to 22.9° the maximum available input from the autopilot. As the airspeed continued to decrease and with the control wheel deflected to, and remaining essentially at, the 22.9° left-wing-down deflection, the airplane began rolling slowly to the right, reaching a wings-level attitude by 1013:58 and then continuing on into a right-wing-down attitude. (See figure 1.)

By 1014:33, the airspeed had decreased to 225 KIAS. Despite the 22° left-wing-down control wheel deflection, the airplane had rolled 23° right-wing-down. (See figure 2.) The airplane's pitch attitude, which until this time had remained constant at 3.1° noseup, now decreased to 1.8° noseup and remained at that angle for about 5 to 6 seconds before returning to the original noseup attitude. During this period, the airspeed increased about 1 KIAS and then began decreasing again. The airplane continued rolling to the right at an increasing rate. In addition, the airplane had begun descending at a rate of about 1,200 feet per minute.

By 1014:50, the airplane had descended to 40,442 feet, the airspeed had decreased to 221 KIAS, and the airplane had rolled and pitched to a 64° right-wing-down and 4° nosedown....
"

In the end, the airplane had rolled a full 180° to the right and the pitch had reached 67° nose down.
Had the event happened at night, the captain wouldn't have recovered the flight.
That crew propbably holds the record of the fastest speed on a 747.

Report is here thanks to the University of Bielefeld team :
Dynasty 006, 747SP Accident Report
Contrail designer
 
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Starlionblue
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RE: Why Did Airbus Eliminate The Yoke?

Sun Dec 14, 2014 2:33 am

Quoting Pihero (Reply 48):
Quoting Starlionblue (Reply 43):
Quoting SEPilot (Reply 33):
Wasn't the primary problem with Colgan 3407 that they let the airspeed decay?

Speed decay --> increased AoA --> increased pitch angle --> yoke full aft... similar situations.

Of course, they did not have thirty-plus thousand feet of altitude in which to try a correction.

Indeed.

You have to make up your mind : Your statements are a bit contradictory :

Ahem. That wasn't me. I just said "indeed" since Colgan Air did indeed not have a lot of altitude for fixing an issue.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

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