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Subject: B787 Info From A Ua Pilot


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#41 Kip Powick

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Posted 14 May 2012 - 01:31 PM

Who among our control column proponents has actually flown the Airbus sidestick operationally for at least a couple of years or more?


Well you got me there Jeff.. :blush: ..While in Toulouse France, I flew the Concorde SIM (Ram's horn CC), the A310 SIM- WD pilot course- (normal CC) and the A320 SIM (SS) and because of my background, preferred the A310. The Concorde Ram's Horn felt like I was on the end of a plow......back on the farm. The A310 was normal/good and of course the A320 was SS and I don't think an hour in the SIM is enough time to be adament that I "totally dislike" the SS......

My opinion about CC vs SS is purely based on my previous transport, (CV580/C130),experience and the fact that the GNF is instantly aware that there has been a control surface input by the GF...Perhaps it was more important to me to have that visual cue as I was a QFI/ICP on those birds and with students......well, I'm just say'n. :biggrin1:

I seem to recall in the distant past that an A320 went in near Stuttgart and some 'aviation expert' did a case study and felt that perhaps the accident would not have happened had the GNF been aware of what the GF was doing with respect to control inputs..and I know......just another 'aviation expert's opinion' but most opinions are based on what one sees, reads and hears :biggrin2:

And as you, and most others, know it's all water under the bridge out here in Dotland :Grin-Nod: :Grin-Nod: ......

#42 Pivot

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Posted 14 May 2012 - 05:58 PM

Well I think we've beat this "stick" thing to death. :biggrin1:
How about the new Lav in the 787? Do the pilots have their own or do they still need to mingle with everyone else?

#43 inchman

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Posted 14 May 2012 - 06:06 PM

Who among our control column proponents has actually flown the Airbus sidestick operationally for at least a couple of years or more?


I'm a CC proponent and flew the 320 for 9 years.

Yeah... it interferes with dinner and prevents providing pilots with a full keyboard, but multi-sensory inputs have proven, over the years, to be advantageous to situational awareness. Manufacturers have combined visual, auditory and tactile sensory inputs into helping pilots identify the current condition for decades. The position of the control column provides a visual and tactile reference for the position of the controls when a pilot may not think to look at the EICAS for control position as they try to figure out what's happening using the PFD.

The control column position answers the question "What's HE doing now?" (as opposed to the standard Airbus phrase "What's IT doing now?".)

#44 boestar

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Posted 14 May 2012 - 06:55 PM

The only thing I have against the SS is the complete lack of tactile and visual feedback to the pilot. If I am the PF and pull the stick back there is no indication to the PNF that I have done so other than the plane making the maneuvre requested. this leads to the questions? What is it doing or what are you doing? In the conventional Aircraft the PNF can see and feel the yoke moving and see the command inputs being made withoug looking at the PF.
I a situation like the AF accident it could well be that no one would think to look at the input on the SS because they are looking at the instruments trying to figure out what the "airplane" is doing. Honestly in a situation where you are trying to unravel a mystery it is not necessarily the easiest thing that is looked at first. Why are we falling from the Sky? Would the first question you ask be hey are you pulling back on the stick????? Probably not because you are busy looking at everything else and besides why would someone pull back on the stick in a stall? right?

As don says the SS is used in millions of flights by thousands of pilots and most like it and I understand why. What I would like to see is a study done to see the reactions as described above in both types with crews that had no idea what to expect and see if the CC provides information that is missing from the SS Cockpit. Would the reactions be different between the crews? would the resolution be found faster in one or the other?
Don: has this ever been done that you know of?
Passive communication is a powerful tool that we use everyday without knowing it. This is just one form.

#45 JL

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Posted 14 May 2012 - 08:41 PM

I think that most of the folks participating in this conversation of SS vs CC are misapplying the AF447 event as an example that SS is less intuitive/helpful in emergency situations. The fact that the flight crew were unable to recover is a clear indication that their cognitive abilities were vastly compromised; maybe even to the point of not being able to function at all. The CVR would be most telling if this were the case. Below is an excerpt from a lengthy review of studies that looked at cognition vs stress. The entire paper can be found here. Stress and Cognition: A Cognitive Psychological Perspective. The bottom line appears to be that when you reach a certain level of arousal/stress, any configuration of flight controls/instrumentation results in successful outcomes. Throw in high levels of stress which lead to a choking or panic situation and the arguments for which control system is better become meaningless. The unfortunate part of all of this, is that there is virtually no way to simulate panic for the purposes of flight deck design or training. The paper brings up skydiving as an example (maybe not the best) of poor performance under high levels of stress. A simple control, the pull chord on the reserve parachute, is not found in the hand of the deceased, rather, their hand is still on the chord of the primary parachute which failed to open.


Panic is a different stress state, and typically results in a more severe form of
performance degradation than choking. When panic occurs, behavior becomes
primitive; if the person thinks at all, it is maladaptive automatic thinking (Katz &
Epstein, 1991). Panic is not just a matter of reverting to behaviors that had been
learned earlier or to memory representations in an explicit form. Panic is
characterized by an even more rudimentary, instinctive kind of behavior aimed at
survival. Rather than “overthinking” the situation, a panicked person stops
thinking altogether and is inclined to react in the most basic way to get out of the
situation or to escape the stressor. Stress appears to cause explicit memories to
become unavailable or irretrievable. In a panic state, short-term memory seems to
cease functioning. The person just freezes, that is, fails to respond, responds in an
automatic but unskilled way, or reverts to primal instincts . Moreover, high
arousal, as under stress, results in perceptual narrowing (Easterbrook, 1959). The
range of cues or sources of informational input that an organism might use to
escape the situation is reduced. The panicked individual focuses, indeed often
obsesses on one aspect of the environment, usually to the neglect of information
that could eliminate the stressful condition. The consequence is that, even though
the goal is survival, performance is functionally maladaptive (Katz, & Epstein,
1991). To use another bit of sports jargon, coaches have been known to refer to a
state of panic as “brain lock.” The cognitive performance system is locked down.

Edited by JL, 14 May 2012 - 08:42 PM.

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#46 J.O.

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Posted 15 May 2012 - 03:05 AM

That is exactly my point, JL. No one on either side of this little debate has faced a scenario like the one the AF447 crew faced. Yes much of it was of their own doing but whether we accept it or not, what they did made sense to them at the time. Once they got into the coffin corner of not understanding what was really happening, they ended up in a state of cognitive tunnel vision and were powerless to do anything about it. Short of being in an airplane that would either tell them exactly what to do or take over and do the recovery itself, I doubt that anything would have changed it.

#47 Kip Powick

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Posted 15 May 2012 - 03:29 AM

Just to clarify, I am not advocating that a CC would have saved AF447...in my opinion, the entire front end had no idea what had happened to the aircraft, (stall). Heck, there is even the possibility that if the aircraft had had a CC they would have held it full back in an attempt to recover.....the demise of AF447 was most likely due to the fact that none of the pilots recognized that they had "stalled" the aircraft.
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#48 blues deville

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Posted 15 May 2012 - 04:48 AM

Who among our control column proponents has actually flown the Airbus sidestick operationally for at least a couple of years or more?


I had the pleasure of flying A320's for nearly two years. I initially did the transition kicking and screaming but once I accepted the differences Airbus offered, it was enjoyable to fly. The biggest adjustment for me I was the lack of 'feel'. The 'eye/hand' coordination required to rotate a large aircraft no longer included the weight feeling in the controls. However, once the sim training was complete I was just as comfortable with the FBW and SS as with any previous conventional type.

I now fly a full FBW/CC aircraft with lots of gadgets to make anyone (including me) look good.

#49 boestar

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Posted 15 May 2012 - 08:31 AM

I am with kip, I used the LIKE word as to the situation.

My point being that in a similar incident had a pilot walked into the cockpit without knowing anything else, a CC would indicate what the aircraft was being told to do where a SS just sits in the middle with no visual/tactile feedback. Walking into a cockpit and seeing the CC full aft with a non existent airspeed would kick me in the face as to what was going on, i would then look for confirmation anywhere possible. Walk into an airbus and your only indication is fluctuating instruments and a decaying altitude with no indication of what the aircraft is being asked to do.

#50 Don Hudson

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Posted 15 May 2012 - 09:34 AM

J.O.

Once they got into the coffin corner of not understanding what was really happening, they ended up in a state of cognitive tunnel vision and were powerless to do anything about it. Short of being in an airplane that would either tell them exactly what to do or take over and do the recovery itself, I doubt that anything would have changed it.

There is some aeronautical engineering data from an extremely good source that indicates that, although requiring attitudes which line crews would not be comfortable with at low altitudes, the aircraft could have been recovered as late as 6000'.

Some explanation of the graph is in order:

The graph plots CAS against Flight Path Altitude. There is no time element in the graph. The bottom (x) axis is CAS, the side, (y) axis is Altitude in ft.

The yellow line is the flight path CAS derived from an exhaustive re-analysis of the DFDR data in the BEA Third Interim Report.

The purple line is CAS. The CAS starts out at roughly 275kts, slightly increases then rapidly drops to about 120kts (purple line moving to the left, still at FL350). We can also see the rapid, initial climb against the loss of airspeed. Times are indicated in blue and begin at 02:10:00, the time of the UAS event.

The purple line then shows increases/decreases in the actual CAS as the aircraft descends.

The black solid line is the Vs1g stall CAS.

The black dashed line is the Vs2.5g.

The black dotted lines show Mach Number.

The group of lines extending to the right, off the actual CAS (purple) line, represent increases in the CAS in 3 recovery scenarios which involve pitching the aircraft down to reduce the AoA and unstall the wing.

The first set of three lines extends to the right at FL350, the next group at FL200 and the last line at about 6000ft.

Each of the three lines indicates potential recovery (unstalling the wing) at various rates-of-change of the AoA and pitch attitude.

The first set at FL350 indicates the nature of the recovery (in terms of altitude lost as speed is gained and AoA is reduced), when the aircraft is pitched down to 10deg and the AoA reduction (from a nominal 35+ deg), of 3, 2, and 1 degree per second.

The second set at FL200 indicates the nature of the recovery at 20deg ND pitch, 10deg ND pitch and 5deg ND pitch, with a reduction in AoA of 2deg/sec.

The third, I am assured, is doable, but the author of this data does not expect that a line crew would pitch the aircraft to 10deg ND at 6000' with a descent rate of 10,000+ fpm down. But, he says, it can be done.

The extended lines have three components - red, yellow and blue.

The red portion of each line indicates that the wing is still stalled even as CAS increases.

The yellow portion is the recovery portion as AoA reduces from a stalled to an unstalled wing.

The blue portion indicates the "run-out"...the continued descent and increased speed as the aircraft is leveled off while avoiding the secondary stall.

Off-topic?
This is off-topic in one way, but very much on-topic in another way. It indicates that perhaps not enough is known and understood or even taught in ground school and recurrent training, regarding high altitude, high Mach No., swept-wing aerodynamics and in particular, the dynamics of the stall of these kinds of aircraft.

The argument for teaching/learning more about these areas is in the trended data where over the past eight years or so, almost a dozen transport category aircraft accidents, many fatal, have occurred when crews have stalled and lost control of their aircraft.

My understanding of jet transport flight came almost exclusively from D.P. Davies and my own self-directed study after I joined the airline. I thought jet transports stalled at AoAs of 12 to 15deg. They do, but Davies only discussed the approach case, when all the high-lift devices were out, (1972).

I did not know, until AF447 and detailed discussions with two aeronautical engineers regarding a deeper understanding of Mach effect that our transport aircraft are always about 1 to 3 degrees above the stall AoA in cruise. The important corollary to this fact is, of course, that changing AoAs at very high Mach numbers is very difficult. The rapid loss of energy/airspeed as a result of the instant pull-up in the AF447 accident brought the Mach down to the point where the Mach number stall AoA and the actual AoA met, and the aircraft stalled...within about 30 seconds of the initial event.

I think these are important understandings about one's aircraft. Has anyone here ever been exposed to these notions in ground school or recurrent sim training? Heck, I never once had a UAS abnormal in 35 years of recurrent training or even a discussion about it.


Posted Image

Edited by Don Hudson, 15 May 2012 - 10:08 AM.


#51 Don Hudson

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Posted 15 May 2012 - 10:53 AM

Boestar - I'm not aware of any studies, nor would I expect any to be at the "front lines" of academic or engineering discussion given the success of the SS concept and design. Where one might expect it is in the BEA Final Report, which is "event specific". I wouldn't, for example, expect the design to be among any recommendations for change.

I believe this because all previous and present documents and SOPs concerning the recognition of and response to the stall do not include either SS or CC position even though the arguments may have some anectdotal validity.

Among the listed, standard primary indications of the stall are a very high descent rate which cannot be arrested regardless of pitch or control input. From the apogee, and when the captain entered the cockpit until impact, this indication* was absolutely clear on both PFDs and the ISIS, all of which had IVSI and altitude information. To give an idea of the rate, on a round-dial steam altimeter the needle would be going around the dial about every three seconds. The pitch was mostly 15deg NU, the IVSI about 20,000fpm at its highest.

The sim takes full, forward SS to achieve 10deg ND. The THS slowly winds back from 13deg NU, the FPV slowly creeps up the PFD from the bottom, at 35deg, to about 10deg which about matches the pitch attitude, and the wing unstalls. It takes about 40 seconds and between 12 and 15 thousand feet starting at FL350. Because the air is thicker, this altitude loss is much less at lower altitudes.

Don

*the IVSI is both IRS and barometrically-driven, so is reliable with U/S ADRs.

#52 hollywud

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Posted 15 May 2012 - 12:55 PM

Richard, look what you've started! A little comment about having a table in the cockpit and the Airbus vs. Boeing crowd pounce. It happens every time. Opinions aside (because after all it's only opinions being expressed here), if yokes were really superior, I wonder why the Space Shuttle designers opted for the side-stick? Just curious............

#53 Mitch Cronin

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Posted 15 May 2012 - 01:24 PM

I think the timing of all that happened worked against them. Specifically, the left seat guy, having just been hit with a problem he'd never trained for, which makes him doubt his instrumentation in the first instant - and who had no trustworthy visual clues of the moves made in error by the PF in the right seat (ie the missing CC) ...had little hope of identifying the problem, especially after he himself had verified the 'pushing forward gets the stall warning back' oddity.

I further think that needs correction. Stall warning should not be so inhibited, when the bird is in the air.

I've been having a devil of a time with written communication of late, but I'd really like to hear someone address those two points... and tell me why they're not part of a serious safety discussion?

Remember the phrase, "fat, dumb, and happy"? ... there they were.... and then, "DING".... an assortment of information you didn't want shows up telling you all sorts of interesting failures are occurring... you hear your partner say "I have control", but you don't see him pulling on his little sidestick because you're busy trying to assimilate all this new information you didn't expect, and as you do so, some of it confirms your interpretation that some of your instrumentation cannot now be trusted.... when you do look back to see what and how your partner is doing with that first fly the airplane business, nothing you see makes any sense... you take control and push on the stick, because what you see looks like you may be stalled.... but when you do, the stall warning comes back! Can you see the 'thought balloon'? ---- "ok, I don't know what's happening either, I shouldn't have taken control - good, he's taken it back"...

I can't answer for any of these fellas, but of the three of them, that guy, in the left seat and PNF when it all started.... his ownership of any mistakes are, in my mind, fully explainable. The ship failed him (and his training, and the other guys).
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#54 DEFCON

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Posted 15 May 2012 - 01:51 PM

First the qualifier; I have no SS experience. On the other hand, I’m not sure an opinion respecting the good, the bad and the ugly of the CC versus SS debate is all that relevant to the present discussion?

From the AF 447 investigation we know, the FDR data depicting the position of the L/H SS throughout the event was critical to the investigators understanding of the ‘causal mechanics’ behind the ac’s deviation from controlled flight.

That being the case; why do we accept ‘after the fact’ knowledge of the SS position as crucial to an accident investigation, but not so ‘critical’ to a crew’s appreciation ‘ of what might be going on in ‘real time’, and of course, before an ‘after the fact’ analysis is required?

From my POV, I believe the so-called ‘accident’ would have been little more than an ‘incident’ had the F/O and for certain, the Captain, been able to instantly note the position of said SS.

#55 Mitch Cronin

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Posted 16 May 2012 - 10:36 AM

Hmmm... Ok, responses not overwhelming me.... Maybe I'll try asking another way...

Is there any large transport category aircraft built, which wouldn't be in a stalled condition following 30 seconds of sustained full-aft elevator application (my apologies for my earlier error in calling it a minute, it was 30 seconds to the aft & left stops)??

Is there any pilot here who could envision a pilot qualified to fly any of those aircraft, who, if presented with that situation in the presence of a control column, would fail to recognize it, and it's significance? IOW, imagine you're the PNF.... you probably believe you'd already have understood and corrected the problem, but imagine you hadn't.... do you think you could fail to notice a CC held full aft/left for 30 seconds? ....and then, of course, the question would be, ok, so you notice... does that help you understand your situation any better than not noticing? (as you quite possibly wouldn't, I believe, with the SS)? I think it does.

#56 Don Hudson

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Posted 16 May 2012 - 03:24 PM

Hi Mitch;

Re, "Is there any pilot here who could envision a pilot qualified to fly any of those aircraft, who, if presented with that situation in the presence of a control column, would fail to recognize it, and it's significance? IOW, imagine you're the PNF.... you probably believe you'd already have understood and corrected the problem, but imagine you hadn't.... do you think you could fail to notice a CC held full aft/left for 30 seconds? ....and then, of course, the question would be, ok, so you notice... does that help you understand your situation any better than not noticing? (as you quite possibly wouldn't, I believe, with the SS)? I think it does."

I'll give your questions a try, but I did address your second question in an earlier response which cites two separate accidents in which the CC was held fully back, in full view of all crew members, all the way down to the impact with terrain. I don't think any crew member "failed to notice" the position of the control column in each accident. But the stall was either not recognized or the instruments not believed, but for whatever reasons, no action to unstall the wing was taken and the control column was held full back until impact.

The AF447 PNF didn't fail to notice the pitch attitude of the aircraft and told the PF to get the nose down. What he failed to do was take control when it became quickly and abundantly clear that the PF was in over his depth and primal, self-preservation emotions had quickly taken over and displaced situational awareness and SOPs.

Re, "Is there any large transport category aircraft built, which wouldn't be in a stalled condition following 30 seconds of sustained full-aft elevator application (my apologies for my earlier error in calling it a minute, it was 30 seconds to the aft & left stops)??"

No, not unless that transport secretly has a full set of afterburners or JATO bottles standing by... ;-)

I would like to emphasize this notion as strongly as I can - for a transport pilot, no matter how achieved, a pitch attitude of 10 to 15deg, achieved in 10 seconds with a 1.55g instant pull-up, at FL350 is a very scary, very serious departure from controlled flight, particularly when it is done without announcement, coordination, reference to or calling for any checklist, drill or even just calling out what is being done. There was no emergency here and no need to act swiftly - the airplane was in no immediate danger. Given this, I would expect the other crew member to take control and keep it. Such a pitch-up isn't a loss of control but it turned into that within 30 seconds.

To achieve this pitch attitude did not require full back stick, and would not require a "huge" CC displacement. I figure back about four inches would be sufficent, (out of a throw of say, 10 or 12" from fore and aft from neutral or so - others should correct me if this is off).

In responding to questions, I also offered the point of view that stall recognition is set out in the AOM and it does not require or state the need to observe the CC position. One of the key metrics in stall recognition is being unable to arrest a rate of descent with a positive pitch attitude. That means the nose must be lowered to reduce the wing's AoA. This is the SOP. For whatever reason, the crew never changed their approach to the problem and, despite clear indications on the PFD in terms of rate of descent and pitch attitude.

Does this help at all?...Not sure what else is missing.

Best

Don

Edited by Don Hudson, 16 May 2012 - 04:08 PM.


#57 Mitch Cronin

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Posted 16 May 2012 - 04:29 PM

Thanks Don.

I guess where I'm having trouble is in the expectation of immediate response from the PNF, given all that occurred in such a short timeframe.... and given that, due to circumstances, he possibly had no idea the pitch-up was either real, or pilot induced. You are evidently adamant that he indeed should have, and I'm saying you took away one of his best clues when you went to the SS.
I tried to say this earlier, but I really rot at communication these days, ...: Evidence that others have missed the clue, surely is not evidence that the clue is meaningless, nor is it any indication that there haven't been oodles of would-be incidents/accidents that became non-events because of that clue.

Have I missed something large? ...it seems pretty significant to me, but I know I my thoughts are often offside....?

#58 Don Hudson

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Posted 16 May 2012 - 04:54 PM

Mitch - Re, "I tried to say this earlier, but I really rot at communication these days..." You!!? Nope - only in your own mind, eh? But I sure know how you feel - I think I'm the one who's terrible at communications these days - can't write a sensible sentence or type to save my life. Maybe its both of us...maybe we're okay and its the rest o' the world. Yeah. That's IT!

Don....(I think)

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Posted 16 May 2012 - 05:41 PM

Maybe they were trying to engage alpha floor. In the sim the alpha floor demo is conducted by placing the thrust levers in the idle detent, pulling and holding full back stick. The airplane convincingly flies out at full thrust and 20+ degrees nose up "automatically".
Granted 200AGL is far different than FL350 but in their mental state, perhaps the alpha floor demo was a factor. Did any of those pilots have experience on types other than airbus? Was PF all cadet-jet-airbus lifer, never having bombed aroud in a Dash-8 or B-1900 or Navajo, Beaver, or Cessna? That is the future of these sim-jockey MPL's that Europe seems so hot for.

#60 Don Hudson

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Posted 16 May 2012 - 05:47 PM

Mitch;

Re, "Evidence that others have missed the clue, surely is not evidence that the clue is meaningless, nor is it any indication that there haven't been oodles of would-be incidents/accidents that became non-events because of that clue."

And just because something isn't included in the SOPs for stall recognition doesn't mean it is meaningless - so yes, true statement.

It can't be in the realm of "SOPs" but it could be an indication that all is not well - it's airmanship, but so is realizing what a lot of blue on the artificial horizon means at FL350.

I think the point being made is, the SOPs were instantly out the window along with any cockpit discipline and, as others have observed, in the case of AF447, it likely wouldn't have made any difference at all. Did it make a difference in the thirty-six other UAS events? We don't know - because they maintained control of the aircraft and we don't know why although I think it is pretty obvious: they did "nothing" instead of something, and waited, because it wasn't an emergency.

Don