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Thread: Pitot Tube Failure

  1. #141
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    The two good references you still have are attitude and thrust level and you use these to establish an approximate safe airspeed and angle-of-attack.
    So sayeth Evan on 8/9/2019 at 19:17Z with a little dot on the end of the sentence
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    Quote Originally Posted by 3WE View Post
    So sayeth Evan on 8/9/2019 at 19:17Z with a little dot on the end of the sentence
    Holy hydraulics, Batman, did he really just say that?!

  3. #143
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    What we have here is LOSS OF COMMS

  4. #144
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    Quote Originally Posted by Evan View Post
    This is the fallacy and the sticking point. Pierre Bonin DID know how to fly an airplane.
    There is substantial evidence that he didn't know. Not at that moment at least.

    I believe he did what he did intentionally...
    You mean that he intentionally pulled up a 1.5G 7000 fpm 2500 ft climb and when the plane stalled he kept "puling up all the time" (in his own words)?
    How is that NOT contradictory with your first statement that he DID know how to fly an airplane?
    Again, EVEN IF (which I doubt) his intention was to climb, that is NOT the way to do it.

    No no no. I now realize that no such procedure exists for what happened to AF447 (You see, I am learning something here). What I'm advocating is a procedure for loss of autoflight and airspeed disagree at cruise-level altitude. Bonin noticed the airspeed disagree within seconds of losing the autopilot. Essentially it would go something like: LOSS OF AUTOPILOT > CROSS CHECK AIRSPEEDS > If disagree exists, PF do this, PNF go to this procedure... Currently, there doesn't seem to be any standard procedure for this scenario. Even after AF447!
    There was a procedure then and there is one now. It is titled "UNRELIABLE SPEED INDICATION" and is triggered by an UNRELIABLE SPEED INDICATION or an ADR CHECK ECAM message.

    It should go like this (ATL, please make the needed corrections):

    [Sound of AP disconnect]
    PF: I have control, troubleshoot please (and focuses on keeping the plane stable, anything not crazy will work)
    PNF: We have ECAM messages, alternate law, protections lost, thrust lock, move thrust levers, rudder trim limit lost, use ruder with care
    PF: Understood
    PNF: And we have some crazy speeds indications, the 3 of them differ and are showing crazy low airspeed and are unstable and coming on and off, unreliable airspeed
    PF: Agree, unreliable speed, safe conduct of flight is not impacted, QRH procedure for unreliable speed please.
    PNF: Unreliable speed, got it... here it is... if safe conduct of the flight is impacted, no... to level off to troubleshoot...
    PF: We are leveled off
    PNF: Ok, then... flight technique, adjust pitch for the required flight path, if pitch tends to increase, airplane slow, increase thrust, if pitch tends to reduce, airplane fast, reduce thrust.
    PF: Got it.
    PNF: When flight path is stabilized... ok and the troubleshooting starts. Let me know when ready.
    PF: Ok, give me a second.
    PF: Ok, stabilized.

    Instead it went like this:

    [Sound of AP disconnect]
    PF: I have control (and starts to pull up a 1.5 7000fpm 2500 ft climb)
    [Cricket] Stall Stall
    [Cricket] Stall Stall
    PNF: We lost the speeds

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
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  5. #145
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    Quote Originally Posted by Gabriel View Post

    There was a procedure then and there is one now. It is titled "UNRELIABLE SPEED INDICATION" and is triggered by an UNRELIABLE SPEED INDICATION or an ADR CHECK ECAM message.
    Indeed.

  6. #146
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Gabriel View Post
    ...It should go like this (ATL, please make the needed corrections):

    [Sound of AP disconnect]
    PF: I have control, troubleshoot please (and focuses on keeping the plane stable, anything not crazy will work)
    PNF: We have ECAM messages, alternate law, protections lost, thrust lock, move thrust levers, rudder trim limit lost, use ruder with care
    PF: Understood
    PNF: And we have some crazy speeds indications, the 3 of them differ and are showing crazy low airspeed and are unstable and coming on and off, unreliable airspeed
    PF: Agree, unreliable speed, safe conduct of flight is not impacted, QRH procedure for unreliable speed please.
    PNF: Unreliable speed, got it... here it is... if safe conduct of the flight is impacted, no... to level off to troubleshoot...
    PF: We are leveled off
    PNF: Ok, then... flight technique, adjust pitch for the required flight path, if pitch tends to increase, airplane slow, increase thrust, if pitch tends to reduce, airplane fast, reduce thrust.
    PF: Got it.
    PNF: When flight path is stabilized... ok and the troubleshooting starts. Let me know when ready.
    PF: Ok, give me a second.
    PF: Ok, stabilized...
    A bit of disconcurment.

    More like this:

    HAFDNHPF: HOLY CRAP, WHAT'S IT DOING NOW, WE'RE GOING TO DIE, EVERYTHING HAS GONE OFFLINE, THIS FBW CHEAP COMPOSITE CRACKERBOX IS GOING TO KILL US, I HAVE NO IDEA WHATS GOING ON, I LOVE YOU MRS. PF!!!!!

    PNF: Just fly the plane...just like a 172...fly the plane...even if we're going to die, keep flying it to the end...

    [Unknown]: Ok, the PLANE seems to be ok...bejebus, now if we can figure out this phugoid automation...I'm gonna need a minute...

    (My version does a little better job capturing the so-called 'startle factor'.)
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  7. #147
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    There is substantial evidence that he didn't know. Not at that moment at least.


    You mean that he intentionally pulled up a 1.5G 7000 fpm 2500 ft climb and when the plane stalled he kept "puling up all the time" (in his own words)?
    How is that NOT contradictory with your first statement that he DID know how to fly an airplane?
    Again, EVEN IF (which I doubt) his intention was to climb, that is NOT the way to do it.


    There was a procedure then and there is one now. It is titled "UNRELIABLE SPEED INDICATION" and is triggered by an UNRELIABLE SPEED INDICATION or an ADR CHECK ECAM message.

    It should go like this (ATL, please make the needed corrections):

    [Sound of AP disconnect]
    PF: I have control, troubleshoot please (and focuses on keeping the plane stable, anything not crazy will work)
    PNF: We have ECAM messages, alternate law, protections lost, thrust lock, move thrust levers, rudder trim limit lost, use ruder with care
    PF: Understood
    PNF: And we have some crazy speeds indications, the 3 of them differ and are showing crazy low airspeed and are unstable and coming on and off, unreliable airspeed
    PF: Agree, unreliable speed, safe conduct of flight is not impacted, QRH procedure for unreliable speed please.
    PNF: Unreliable speed, got it... here it is... if safe conduct of the flight is impacted, no... to level off to troubleshoot...
    PF: We are leveled off
    PNF: Ok, then... flight technique, adjust pitch for the required flight path, if pitch tends to increase, airplane slow, increase thrust, if pitch tends to reduce, airplane fast, reduce thrust.
    PF: Got it.
    PNF: When flight path is stabilized... ok and the troubleshooting starts. Let me know when ready.
    PF: Ok, give me a second.
    PF: Ok, stabilized.

    Instead it went like this:

    [Sound of AP disconnect]
    PF: I have control (and starts to pull up a 1.5 7000fpm 2500 ft climb)
    [Cricket] Stall Stall
    [Cricket] Stall Stall
    PNF: We lost the speeds
    There is no argument between us that CRM failed here and that it was a major causative factor.

    And thank you for pointing out that a procedure exists for unreliable airspeed. Of course, I already know that.

    But, if what ATL is telling us about the new (circa 2006) 'combined' procedure replacing the old, split procedures is still the official procedure, even after the lessons of AF447, than this what I'm taking issue with.

    There used to be a procedure for this. If called for immediate actions to stabilize using engineering-derived pitch and power settings (5deg/CL), as well as the necessary system reconfigurations. It was included as a memory item AFAIK. It minimized the risk of pilot improvisation driven by erroneous indications and clouded judgement. Three years before the scenario of AF447 revealed itself, Airbus decided to replace it with this one:

    Click image for larger version. 

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    I can only surmise that this was done with the assumption that UAS doesn't typically occur at cruise level, FDnH phases of flight, where errors are amplified and tolerances reduced, and done without deeply understanding the human factor issues such an event creates. That is somewhat understandable in 2006, but not in the years following the lessons of AF447.

    First of all, why are you prioritizing an ADR CHECK PROCEDURE to 'identify the faulty ADR(s) and switch it (them) off'? You do NOT want to do that! The speeds in this scenario will self-restore, typically within a minute (as they did with AF447). Secondly, it's pointless: there is nothing wrong with the ADR's. The procedure doesn't apply to this (newly revealed) failure situation. Thirdly, there is a 'fingerprint' of failures that identifies this situation. The obvious ones are the sudden loss of autoflight (cavalry charge) and Normal Law, followed by the recognition of airspeed disagreement. The pitots have become simultaneously contaminated by a temporary environmental condition that will shortly alleviate. The only task is to manually stabilize, reconfigure certain systems and to remain in stable flight for approx one minute.

    What I'm saying is that, for this scenario, we should return to the order of the original procedure because the most important actions (and only necessary actions) are boxed in the IMMEDIATE ACTIONS (as a memory procedure) part of that procedure. No ADR CHECK PROC is needed to get things back on track (although the procedure should be run through, once everything is stable, just in case).

    This is why I suggested to ATL that he might be misinterpreting the application of this procedure, that is for a different scenario than the one made widely known by AF447. Either that or someone higher up isn't thinking this through. If ATL is right, then his airline is lacking an appropriate procedure for an AF447 failure scenario, and nothing except sound pilot judgment and proficiency (in a situation that has been shown to degrade these things) defends the aircraft against erroneous pilot judgment and dangerous improvisation.

  8. #148
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    There used to be a procedure for this. If called for immediate actions to stabilize using engineering-derived pitch and power settings (5deg/CL), as well as the necessary system reconfigurations. It was included as a memory item AFAIK. It minimized the risk of pilot improvisation driven by erroneous indications and clouded judgement. Three years before the scenario of AF447 revealed itself, Airbus decided to replace it with this one:

    Click image for larger version. 

Name:	uas-adr.jpg 
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ID:	27177
    Nope, THAT was the old procedure(s). Tow different procedures, one for unreliable airspeed and one for ADR check, and you had to decide which one to use depending on whether the safe conduct of the flight was impacted or not. And at some point one pointed to the other and vice versa.

    3 years before AF it was changed to the new unified version that we discussed (which is located later in the same document) which you execute (the same procedure) for unreliable airspeed or for ADR check, and has the question about whether the safe conduct of the flight is impacted in the beginning of the procedure.

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    --- Defend what you say with arguments, not by imposing your credentials ---

  9. #149
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    Nope, THAT was the old procedure(s). Tow different procedures, one for unreliable airspeed and one for ADR check, and you had to decide which one to use depending on whether the safe conduct of the flight was impacted or not. And at some point one pointed to the other and vice versa.

    3 years before AF it was changed to the new unified version that we discussed (which is located later in the same document) which you execute (the same procedure) for unreliable airspeed or for ADR check, and has the question about whether the safe conduct of the flight is impacted in the beginning of the procedure.
    Ah, I uploaded the wrong page. This is it:

    Click image for larger version. 

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    But please respond to the point I'm making. The red boxed items are necessary to avoid errors and deception. Meanwhile, the instruction for when the affected ADR cannot be identified (as in this case because there is no ADR fault), is to shut them all off. That's rather counterproductive, isn't it? This is why I called it absurd for the situation AF447 was in.

    Again, I see the ADR check procedure as useful when a speed disagree is developing due to a faulty sensor or ADR, but not for a complete loss of speeds, autoflight and normal law due to ice ingestion.

  10. #150
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    Quote Originally Posted by Evan View Post
    Ah, I uploaded the wrong page. This is it:

    Click image for larger version. 

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    Nope, that's the one that applies when the BUSS option is installed. Try again. Page 17.

    Or here:

    http://flightacademy.info/wp-content...-procedure.png

    And to the point you are making, I don't even understand it, but I don't agree that these memory items are necessary to avoid errors.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
    --- Defend what you say with arguments, not by imposing your credentials ---

  11. #151
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Gabriel View Post
    And to the point you are making, I don't even understand it
    Let me explain.

    EVERYTHING MUST be a regurgitated, written procedure (cryptic acronyms are a plus).

    NOTHING can come from traditional airmanship or concepts that broadly apply.

    The sentences end with periods, and it's pretty absolute.

    https://www.youtube.com/watch?v=y_2YcMlKVPQ
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  12. #152
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    Quote Originally Posted by Gabriel View Post
    And to the point you are making, I don't even understand it, but I don't agree that these memory items are necessary to avoid errors.
    The point I am making: where is the procedure for this? Why would you go directly to an ADR fault identification procedure when there is no ADR fault? Why would you shut down all your ADR's when you want to get the speeds back asap? Why would you disable your air data systems when they typically restore themselves in a minute or so? What you want to do is manually stabilize, reconfigure certain deceptive systems and remain in stable flight for approx one minute until the pitots clear and the speeds become reliable again and you can restore autopilot. This is ice ingestion at cruise level in conditions where that can occur, typically in the ITCZ, a failure scenario that is now known to exist. Where is the procedure for that?

  13. #153
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    Quote Originally Posted by Evan View Post
    The point I am making: where is the procedure for this? Why would you go directly to an ADR fault identification procedure when there is no ADR fault? Why would you shut down all your ADR's when you want to get the speeds back asap? Why would you disable your air data systems when they typically restore themselves in a minute or so? What you want to do is manually stabilize, reconfigure certain deceptive systems and remain in stable flight for approx one minute until the pitots clear and the speeds become reliable again and you can restore autopilot. This is ice ingestion at cruise level in conditions where that can occur, typically in the ITCZ, a failure scenario that is now known to exist. Where is the procedure for that?
    Ok, that is a good point. But what procedure calls for all ADRs off? This is required to activate the BUSS only (if installed) AFAIK.

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  14. #154
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    Quote Originally Posted by Gabriel View Post
    Ok, that is a good point. But what procedure calls for all ADRs off? This is required to activate the BUSS only (if installed) AFAIK.
    AFAIK, every ADR CHECK PROCEDURE calls for shutting down any ADR that is faulty (providing erroneous airspeed data), so, when all speeds are erroneous, all are shut off. Also, this isn't the ACTIVATE BUSS PROCEDURE, it is the UNRELIABLE AIRSPEED PROCEDURE. On BUSS-equipped aircraft, BUSS activation is just the automated result of shutting down all the ADRs. But why would you run ADR procedure for unreliable speeds caused by a common environmental phenomena temporarily contaminating the pitots? It's counterproductive. It will delay or prevent the restoration of airspeeds and autoflight. Why would you shut down ANY ADR in this situation?

    Recall that, prior to AF447, Airbus considered the air data system to be very robust due to its multiple redundancies, but didn't seem to fully consider a common environmental vulnerability (ice crystal ingestion at cruise) that renders all that redundancy useless. In the wake of the crash, I expected a new procedure to defend against this newly-revealed threat, to prevent errors and defend against deceptions. So where is it?

  15. #155
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    Quote Originally Posted by Evan View Post
    AFAIK, every ADR CHECK PROCEDURE calls for shutting down any ADR that is faulty (providing erroneous airspeed data), so, when all speeds are erroneous, all are shut off. Also, this isn't the ACTIVATE BUSS PROCEDURE, it is the UNRELIABLE AIRSPEED PROCEDURE.
    Again, where does that come from? Show me.

    Because what I see is, in case of not being able to identify one reliable ADR, above FL250 switch any 2 of them off (the remaining one cannot be used by any automation or speed-based protection since it HAS to consider it unreliable, but the pilots can monitor the resulting airspeed and, when/if it makes sense again, they can try to switch the other ADRs on and compare), and below FL250, IF THE SPEED IS STILL UNRELIABLE, it calls to switch all ADRs off IN ORDER TO ACTIVATE THE BUSS. I wonder how this procedure looks like in non-BUSS airplanes. I also wander why Airbuss doesn't want us to use the BUSS above FL250.

    http://flightacademy.info/wp-content...-procedure.png

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    I suspect that this is the current procedure, not the one in use at the time of Air France (which was also non-BUSS so this procedure would not apply anyway)

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  16. #156
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    Quote Originally Posted by Gabriel View Post
    Again, where does that come from? Show me.

    Because what I see is, in case of not being able to identify one reliable ADR, above FL250 switch any 2 of them off (the remaining one cannot be used by any automation or speed-based protection since it HAS to consider it unreliable, but the pilots can monitor the resulting airspeed and, when/if it makes sense again, they can try to switch the other ADRs on and compare), and below FL250, IF THE SPEED IS STILL UNRELIABLE, it calls to switch all ADRs off IN ORDER TO ACTIVATE THE BUSS. I wonder how this procedure looks like in non-BUSS airplanes. I also wander why Airbuss doesn't want us to use the BUSS above FL250.

    http://flightacademy.info/wp-content...-procedure.png

    Click image for larger version. 

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    I suspect that this is the current procedure, not the one in use at the time of Air France (which was also non-BUSS so this procedure would not apply anyway)
    Inconsistencies...

    I don't think the "new" combined 'Unreliable Speed Indication / ADR Check' procedure is BUSS specific. Note the yellow highlighted parts:

    Click image for larger version. 

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    Again, shutting down ANY ADR's seems counterproductive for the AF447 scenario.

  17. #157
    Senior Member Gabriel's Avatar
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    This procedure that you pictured is specific for BUSS equipped airplanes. Two clues that this is the case:
    - Note the text below the bottom yellow highlighted line.
    - Note the "new procedure" (back then) in page 17 of the same document. It has the pitch/thrust tables, which do not exist in the version you posted because you don't need pitch and thrust tables when you have the BUSS speed tape and GPS altitude displayed in the PFD.
    And this procedure is the one implemented 3 years before AF.
    The one I posted, I believe, is more modern.

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  18. #158
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    Quote Originally Posted by Gabriel View Post
    This procedure that you pictured is specific for BUSS equipped airplanes. Two clues that this is the case:
    - Note the text below the bottom yellow highlighted line.
    - Note the "new procedure" (back then) in page 17 of the same document. It has the pitch/thrust tables, which do not exist in the version you posted because you don't need pitch and thrust tables when you have the BUSS speed tape and GPS altitude displayed in the PFD.
    And this procedure is the one implemented 3 years before AF.
    The one I posted, I believe, is more modern.
    Still, why monkey with the ADRs?

  19. #159
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    Quote Originally Posted by Evan View Post
    Still, why monkey with the ADRs?
    It is written there in the very procedure in the link I provided.
    If the unreliable ADRs cannot be identified yo have to switch off 2 of them to avoid that the automation / protections take as valid 2 incorrect but consistent values (even to the extent of discarding the third and possibly only correct one).

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  20. #160
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    It is written there in the very procedure in the link I provided.
    If the unreliable ADRs cannot be identified yo have to switch off 2 of them to avoid that the automation / protections take as valid 2 incorrect but consistent values (even to the extent of discarding the third and possibly only correct one).
    The automation and protections are already lost. They can't survive total pitot failure. You know this.

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