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Thread: Pitot Tube Failure

  1. #161
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    The automation and protections are already lost. They can't survive total pitot failure. You know this.
    But they can survive 2 pitots giving incorrect but consistent data. That is what you try to avoid and hence turn any 2 ADRs off (but leave 1 on to keep monitoring it).

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  2. #162
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    But they can survive 2 pitots giving incorrect but consistent data. That is what you try to avoid and hence turn any 2 ADRs off (but leave 1 on to keep monitoring it).
    I understand that, but the scenario we are talking about begins with sudden loss of autoflight and reversion to alternate law, followed by the recognition of unreliable speeds. At this point, there is no such danger. Where is the procedure for this event?

  3. #163
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    The automation and protections are already lost. They can't survive total pitot failure. You know this.
    ...and yet pilots can survive using basic stuff...oh the ironing...you have disdain for this.

    On a different angle, are we making any progress?
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  4. #164
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    I understand that, but the scenario we are talking about begins with sudden loss of autoflight and reversion to alternate law, followed by the recognition of unreliable speeds. At this point, there is no such danger. Where is the procedure for this event?
    I don't know the full ramifications, what other things may be affected by 2 matching unreliable ADRs. Autotrim, elevator gain (roll is direct law but pitch is still G-on-stick), stall warning, FD...

    Plus, you cannot establish a procedure for each way each thing can fail. Can the procedure be improved? Maybe, I won't argue that.

    But if you want to know what I really think, this is an ideal situation for a "gimme my plane" guarded switch and then you don't need to turn off any ADR ever in any unreliable speed situation, and you can keep monitoring the 3 airspeed indicators and when the situation is over (if ever) you turn off that guarded switch and give control back to HAL.

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  5. #165
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    But if you want to know what I really think, this is an ideal situation for a "gimme my plane" guarded switch and then you don't need to turn off any ADR ever in any unreliable speed situation, and you can keep monitoring the 3 airspeed indicators and when the situation is over (if ever) you turn off that guarded switch and give control back to HAL.
    Wait a sec... did 3WE hack your account? The system is designed to "give you the plane" and that's where it all begins. The final report concluded that the airplane responded perfectly to commands. Aside from protections and the other aspects that were lost (indicated on ECAM), the FBW was not affected, and if it were, Airbus would have designed it to degrade as well. Because it isn't 'HAL' and regulators were very very very demanding in overseeing its development. If only that were true of Boeing...

    The point is still the point. I can see no purpose to divert CRM to an ADR CHECK procedure, which is actually counter-productive in a situation where the problem resolves itself in a minute or so. The problem wasn't well understood in 2006, but it certainly is now, and it does need its own procedure to follow which does not have at least one pilot distracted on a fool's errand. Perhaps we are not looking in the right place, or perhaps the industry just never took the lesson seriously, or just lacked initiative.

  6. #166
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    Wait a sec... did 3WE hack your account?
    No, and listen carefully- we object to cowboy improvisation that goes against "all" logic and fundamentals and procedures.
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  7. #167
    Senior Member Evan's Avatar
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    Quote Originally Posted by 3WE View Post
    No, and listen carefully- we object to cowboy improvisation that goes against "all" logic and fundamentals and procedures.
    Improvisation never goes against all logic. The question is: is the logic sound? The next question is: Is there something deceiving behind the logic?

    Written and memorized procedures are reliably sound. They defend against deceiving things.

  8. #168
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    Improvisation never goes against all logic, except when it does. The question is: is the logic sound? The next question is: Is there something deceiving behind the logic?

    Written and memorized procedures are reliably sound. They defend against deceiving things, except when they don't.
    Fixed.
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  9. #169
    Senior Member Evan's Avatar
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    Quote Originally Posted by 3WE View Post
    Fixed.
    Ok, you'll have to please explain to me how your logic tells you to do one thing and you do the opposite.

  10. #170
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    Ok, you'll have to please explain to me how your logic tells you to do one thing and you do the opposite.
    We are falling int semantics again. Is a flawed logic (let's say in illogical logic) still logic?

    I can say "1+ adverb = salty pressure" and call it Maths, grammar, cooking and Physics, just not sound at that.

    For me the real question is still, what kind of procedure, memory item or whatever would have prevented the irrational and unbelievable crazy (relentless, 3we would say) pull up that the PF executed the instant the AP disconnected before anybody had any chance to identify remote idea of what was going (which is a pre-requisite for what procedure or memory items to invoke)?

    What was the "logic" that triggered a 1.5G 7000fpm 2500ft climb and then a relentless pull up with the stall warning sounding uninterruptedly during more than 30 seconds and then intermittently with the plane pointing 10 degrees nose up while falling 10000 fpm?
    I'll tell you what logic: an irrational, ignorant, illogical logic.

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  11. #171
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    Ok, you'll have to please explain to me how your logic tells you to do one thing and you do the opposite.
    Almost all logic says, "do not pull up relentlessly"- except for when you are 5 seconds from hitting the side of an obstruction.

    But...it happened...Would you like to explain why that happened? I've offered some why's but do not defend them very strongly.
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  12. #172
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Gabriel View Post
    (relentless, 3we would say)
    Yes.

    I find that to be the best adjective for the sake of brevity and clarity.

    We needed something to contrast with aggressive, but carefully measured with critical attention to the stall situation.

    It's possible it's not a perfect description, but...
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  13. #173
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    We are falling int semantics again. Is a flawed logic (let's say in illogical logic) still logic?
    Are you being Socratic? All intentional actions are driven by logic. Logic can be quite flawed but it is still logic, so no intentional act can "go against all logic".

    For me the real question is still, what kind of procedure, memory item or whatever would have prevented the irrational and unbelievable crazy (relentless, 3we would say) pull up that the PF executed the instant the AP disconnected before anybody had any chance to identify remote idea of what was going (which is a pre-requisite for what procedure or memory items to invoke)?
    Logic can certainly be taught and instilled. If his trained logic was "follow the memorized procedure (assuming one exists) unless it is dangerous to do so (cuz you're fixin' to hit something), then there would be no danger of flawed, improvisation logic ruining the moment.

    What was the "logic" that triggered a 1.5G 7000fpm 2500ft climb and then a relentless pull up with the stall warning sounding uninterruptedly during more than 30 seconds and then intermittently with the plane pointing 10 degrees nose up while falling 10000 fpm?
    I'll tell you what logic: an irrational, ignorant, illogical logic.
    First of all, I have to insist that we stick to the facts. The PF did nothing 'the instant the AP disconnected'. One second later he applied a modest nose up input (while rolling to the limit stops) and it remained modest for about one second. Only then did he make a more pronounced nose-up input to about half the stick limit, followed one second later by a reduced nose-up input, followed by a slightly more than half-limit nose-up input of about one second followed by a sharp reductionand then a gradual reduction to about 1/8 nose-up limit over the next two seconds, followed over the next four seconds by a series of input variations between 3/4 and 1/8 nose-up limit, followed by a steady return to neutral and a momentary nose-down input, followed by another quick nose-up input to about 1/2 limit, followed by a quick return to neutral and then two nose-down inputs. At this point the pitch, which had been steadily increasing, stopped increasing and then actually reduced slightly before very gradually increasing as his stick commands were now varying between 1/4 nose-up and 1/8 nose down.

    That is hardly what you call pulling up 'relentlessly'. There was plenty of relenting. If we are going to ever understand what happened here, we have to stop using that word.

    The potential logic:

    - I am descending and need to regain altitude (logic driven by deceptive indications).
    - I am penetrating a massive storm and the turbulence has just knocked off the autopilot. I need to climb to smoother air immediately (logic driven by mental imperatives).
    - The stall warnings are erroneous because the speeds are erroneous (bad logic, but understandable if you havent read the procedure).
    - I am nowhere near critical AoA at 5° pitch (bad logic, but understandable if you haven't been trained on high-altitude approach to stall).
    - I can safely fly 10° of pitch with full climb power (logic based on false assumption, due to stealth factor and lack of high-altitude manual flight training).
    - The flight directors are back. That means they have restored and I should follow them (he more or less did follow them).

    At this point he reached about 12° nose-up pitch and then began about 45 secs of pitch reduction back to 6°. By then, however, he has lost his SA and is out of his depth, his logic is entirely disoriented, a place we never want pilots to arrive at. From here, logic goes anywhere, including pulling up into a 17° pitch-induced stall.

  14. #174
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    That is hardly what you call pulling up 'relentlessly'. There was plenty of relenting.
    Yeah, whatever. Gray areas...I get it.

    That being said, did the stall ever stop for the whole 37,000 feet?
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    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    Are you being Socratic? All intentional actions are driven by logic. Logic can be quite flawed but it is still logic, so no intentional act can "go against all logic".
    Again, that depends on what you call "logic". Are logical fallacies still "logical"?
    If I say "Some animals eat grass, my cat is some animal, therefore it eats grass and I will feed it with grass", is that voluntary act logical?
    And perhaps most importantly... Are you sure that the pilot really intended (i.e. has the intention, since you are reducing the scope only to intentional acts) to pull a 1.5G 7000 FPM 2500 ft climb the moment that the AP disconnected?


    Logic can certainly be taught and instilled. If his trained logic was "follow the memorized procedure (assuming one exists) unless it is dangerous to do so (cuz you're fixin' to hit something), then there would be no danger of flawed, improvisation logic ruining the moment.
    If you really believe that, I am out of the discussion.

    First of all, I have to insist that we stick to the facts. The PF did nothing 'the instant the AP disconnected'. One second later he applied a modest nose up input (while rolling to the limit stops) and it remained modest for about one second. Only then did he make a more pronounced nose-up input to about half the stick limit, followed one second later by a reduced nose-up input, followed by a slightly more than half-limit nose-up input of about one second followed by a sharp reductionand then a gradual reduction to about 1/8 nose-up limit over the next two seconds, followed over the next four seconds by a series of input variations between 3/4 and 1/8 nose-up limit, followed by a steady return to neutral and a momentary nose-down input, followed by another quick nose-up input to about 1/2 limit, followed by a quick return to neutral and then two nose-down inputs. At this point the pitch, which had been steadily increasing, stopped increasing and then actually reduced slightly before very gradually increasing as his stick commands were now varying between 1/4 nose-up and 1/8 nose down.

    That is hardly what you call pulling up 'relentlessly'. There was plenty of relenting. If we are going to ever understand what happened here, we have to stop using that word.

    The potential logic:

    - I am descending and need to regain altitude (logic driven by deceptive indications).
    - I am penetrating a massive storm and the turbulence has just knocked off the autopilot. I need to climb to smoother air immediately (logic driven by mental imperatives).
    - The stall warnings are erroneous because the speeds are erroneous (bad logic, but understandable if you havent read the procedure).
    - I am nowhere near critical AoA at 5° pitch (bad logic, but understandable if you haven't been trained on high-altitude approach to stall).
    - I can safely fly 10° of pitch with full climb power (logic based on false assumption, due to stealth factor and lack of high-altitude manual flight training).
    - The flight directors are back. That means they have restored and I should follow them (he more or less did follow them).

    At this point he reached about 12° nose-up pitch and then began about 45 secs of pitch reduction back to 6°. By then, however, he has lost his SA and is out of his depth, his logic is entirely disoriented, a place we never want pilots to arrive at. From here, logic goes anywhere, including pulling up into a 17° pitch-induced stall.
    A quarter turn of the steering wheel in your car can be relentless if you are going 100 MPH.
    A 1.5G pull-up is excessive in any non-life-or-death situation.
    A 7000 fpm climb is excessive in any non-life-or-death situation (and then not sustainable for very long).
    Pulling up in response to a stall warning is NEVER the right reaction, even if you think that the stall warning is erroneous. Why did he pull up in response to the stallw arning at the top of the climb?

    I think you are putting too much rationale into the pilots actions that I believe were more irrational, and hence less intentional, than what you think.

    None of us will be able to prove it because the MTR (mind thoughts recorder) was not invented yet.

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  16. #176
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by 3WE View Post
    That being said, did the stall ever stop for the whole 37,000 feet?
    Yes, it sounded continously "only" for some 30 seconds. Then, with the pitots working again, the AOA became so high that the (now reliable) airspeed was erroneously too low, below the lower threshold to consider the AoA measurement "reliable". SO the stall warning became intermittent for the rest of the fall as the plane's speed oscillated into and out of that threshold.

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  17. #177
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    Again, that depends on what you call "logic". Are logical fallacies still "logical"?
    If I say "Some animals eat grass, my cct is some animal, therefore it eats grass and I will feed it with grass", is that voluntary act logical?
    Well, without going deep into psychologism and the semantics of logic—and avoiding mathematical logic altogether—let me just say that 'logic' is more relative and expansive than what we deem 'logical'. A person can have flawed logic, which can be proved illogical, but it is still a form of logic and represented a logical premise to them when it was conceived.

    And perhaps most importantly... Are you sure that the pilot really intended (i.e. has the intention, since you are reducing the scope only to intentional acts) to pull a 1.5G 7000 FPM 2500 ft climb the moment that the AP disconnected?
    No, I don't think that was his intention. I think his intention was to follow the potential logic I described in my previous post. What you are focusing on are the consequences of that intention.
    If you really believe that, I am out of the discussion.
    Where does the danger lie in executing a memorized procedure of 'click clack pitch power (move thrust levers) ECAM QRH (DO NOT shut down ADR's) ride it out? I almost said 'minimal danger' instead of 'no danger', but then I couldn't find the minimal danger. There is, of course, the danger that the procedure will be subject to pilot error, but then that just gets us back to the problem of training and proficency. I'm simply stating that it is more reliable to teach procedure than to teach universal improvisational judgment. How can you argue with that? (note the word 'universal').

    A quarter turn of the steering wheel in your car can be relentless if you are going 100 MPH.
    A 1.5G pull-up is excessive in any non-life-or-death situation.
    A 7000 fpm climb is excessive in any non-life-or-death situation (and then not sustainable for very long).
    Pulling up in response to a stall warning is NEVER the right reaction, even if you think that the stall warning is erroneous. Why did he pull up in response to the stallw arning at the top of the climb?
    You're not reading what I wrote there. Focus on the commands, not the consequences. They aren't that excessive at the phases of flight where he was experienced in manual flight. Obviously, it was excessive in terms of consequences, but he had no G-meter and what makes you think he was watching the VSI? And, as I said, I think he considered the stall warnings to be erroneous because his 'logic' told him they were 'illogical'.

    The bottom line here, really, is that you can choose to try to understand this from the point of view of startle factor, deceiving indications and flawed logic (flawed judgment) driving intentional acts executed with unpracticed skills or you can choose to never understand it at all and just write it off as 'unthinkable acts of poor airmanship'. But only the former (along with engineering improvements) can bring about any meaningful changes to prevent it from recurring.

  18. #178
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Gabriel View Post
    Yes, it sounded continously "only" for some 30 seconds. Then, with the pitots working again, the AOA became so high that the (now reliable) airspeed was erroneously too low, below the lower threshold to consider the AoA measurement "reliable". SO the stall warning became intermittent for the rest of the fall as the plane's speed oscillated into and out of that threshold.
    Please reread what I wrote, and answer the question I actually asked.
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  19. #179
    Senior Member Gabriel's Avatar
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    For the Nth time, if you want to put it as ït as the inputs, not the consequences", then I would not trust this pilot (in the mental state that he had in the moment) to follow any memory items or procedure. Because the procedure would not have been "pull the stick 1/8 back", it would be based on RESULTANT PERFORMANCE or CONSEQUENCES.

    And I don't agree with your false dilemma of you are either with me or shut up. Sorry, there are other choices. There are other ways than this could happen other than "intentional acts based on logic", which I will not repeat anymore.

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  20. #180
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by 3WE View Post
    Please reread what I wrote, and answer the question I actually asked.
    I stand corrected. The correct answer is no, once stalled at about 37500 ft the stall didn't stop at any point, not even close. The plane was fully stalled all the time in its way from the highest point to the lowest point achieved that day.

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