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Thread: Air France Off the Hook on AF447

  1. #41
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    And I say it wasn't. I don't know what is sustainable for you, but I will not call sustainable a climb from which the only way out is a descent because if you don;t descend you will stall and then descend.
    2hr 10min 49: The aircraft has successfully climbed to 37,500. It has not stalled. The pitch is 6 deg nose up. The vertical speed is 1100fpm. The AoA is around 5 deg (just below stall warning activation). If, at that point, autopilot had been restored for that flight level (and it may have been available at that point), the pitch would have reduced and the aircraft would not have stalled. It would have simply continued on its merry way at a higher flight level. That's what I mean by sustainable (the intial climb during the first 45 seconds). That's what I mean by 'succeeded'. I never suggested it was a wise thing to do. I've said quite the contrary.

    2:10:19. It's been 14 seconds since the AP disconnected and 12 seconds since he started playing with the sidestick. The inputs were ONLY nose up and up to 3/4 travel for the first 9 seconds, but for the last 3 seconds his inputs, while still clearly nose-up in average, were slightly more balanced with some instants of very slight nose-down inputs.
    What are you looking at?! The input at 2:10:19 was nose-down to neutral. The inputs over the following five seconds were all slightly nose up (none exceeding 1/4 nose up) returning to nose down thereafter. No inputs after that exceeded 1/2 nose up and, from 2:10: 27 to 2:10:40 most ol the inputs were nose down, a number of them being around the 1/2 nose down mark. Not great stick-handling skills, and yes, always maintaining a nose-up attitude, but also not the 'crazy' sustained upward commands as you have suggested.

    It is not that he climbed but how he climbed what removes any confidence in me that a better procedure would have saved the day with this pilots at the controls.
    Gabriel, are you kidding me?! It absolutely is the fact that he climbed! You don't climb out of cruise level flight without airspeed data! You maintain a safe pitch and power setting! (that little dot is an exclamation point).

    At that time, all 3 altimeters were indicating 35350ft and winding up quickly, all 2 vertical speed indicators were showing a climb of 5500 ft per minutes and increasing, and all 3 attitude indicators were showing 10 degrees nose up. These numbers are already ridiculous for a cruise climb.

    And at that moment, at 2:10:19, all 3 altimeters, all 2 vertical speed indicators, and all 3 attitude indicators were PERFECTLY ADEQUATE for the pilot to know better than to keep pulling up.

    What does the pilot do next? He keeps making ONLY NOSE UP inputs for the next 5 seconds, bringing the vertical speed to 7000 fpm and the pitch to 12 degrees nose-up.
    FIrst, you have to stop confusing my concern for the instrument inaccuracies with the 7000fpm climb. I never said they would conceal something like that.

    I'm theorizing (not declaring) that the expedited climb was intentional, though probably more excessive than intended due to unpracticed skills. The only role the instrument inaccuracies play is in encouraging a departure from level flight in the first place.

    None. I wonder why. After all the procedure did say AP/AT/FD off, thrust levers move. So it surely wasn't the lack of a procedure.
    It was a lack of proficiency on procedure. Memory procedures are meaningless if not committed to memory and practiced recurrently. Such procedures defend against erroneous improvisation.

    I have zero confidence in that. A pilot that, upon AP disconnect, pulls up a 1.5G, 2500 ft, 7000 fpm, 12 degrees nose-up climb, I don't trust him to be able to follow a procedure that involves keeping a given pitch. He was incapable to keep ANY pitch in this incident.
    And I believe it was the lack of a simple, solid procedure that led him to improvise in this way. At that critical moment of surprise, his mind asked 'what do I do?' and, not finding an answer there, made one up based on prior concerns. It needed to find the correct answer there, which most likely would have been there if he had memory-procedure training for this.

  2. #42
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    2hr 10min 49: The aircraft has successfully climbed to 37,500. It has not stalled. The pitch is 6 deg nose up. The vertical speed is 1100fpm. The AoA is around 5 deg (just below stall warning activation). If, at that point, autopilot had been restored for that flight level (and it may have been available at that point), the pitch would have reduced and the aircraft would not have stalled. It would have simply continued on its merry way at a higher flight level.
    Hello? 2:10:49????
    They were doing 215 knots
    In a fully loaded A330
    Yes, the vertical speed was 1100 fpm, but it was "decreasing"
    Which means that they were at less that 1G (and hence lift was less than weight)
    And the stall warning activated 2 frigging seconds after that.
    The moment that they increased the load factor to barely 1G.
    How can the word "sustainable" even cross your mind in relation to the condition at 2:10:49?

    What are you looking at?! The input at 2:10:19 was nose-down to neutral. The inputs over the following five seconds were all slightly nose up (none exceeding 1/4 nose up)
    I am looking exactly at that. Why would a pilot that for 20 seconds had put the airplane in a 10 deg pitch up 5500 fpm climb do, for the next 5 seconds, "slightly" nose up commands and not "decisively" nose down, thus increasing the climb to 12 deg and 7000 fpm? (I put slightly in quotes for a reason: 1/4 travel i equivalent to 1/2 turn in your 2-turns-steering wheel. When was the last time that you used 1/2 turn when cruising, or for the sake of it for anything other than turning a tight corner at slow speed or parking?)

    Gabriel, are you kidding me?! It absolutely is the fact that he climbed! You don't climb out of cruise level flight without airspeed data! You maintain a safe pitch and power setting! (that little dot is an exclamation point).
    But if you do climb, for whatever reason, you don't make a sustained unsustainable climb of 12 deg nose up and 7000 fpm. You have a goal in mind and my over-react, overshoot and oscillate towards that goal.

    I will show you how lack of manual flight skills at altitude look like, WHEN YOU HAVE A GOAL IN MIND (and if you say that the goal was just CLIMB, then I will say that the pilot lacked -at that moment at least- any reasonable airmanship)

    From the BEA:

    Case of TAM flight on 12 November 2003
    This case, which happened to an A330-200, was not one of the thirteen events studiedabove because no crew report was available. However, in the light of the data fromflight AF 447, it seems useful to mention it. In fact, following icing of at least twoPitot probes at FL360, the crew made some high amplitude flight control inputs (tothe stop), sometimes simultaneously. When the AP disengaged, both pilots madepitch-up inputs (one went to the stop) that resulted in an increase in pitch of 8°. Onseveral occasions, the stall warning was triggered due to the nose-up inputs, and thecrew reacted with strong pitch-down inputs. During the 4 minutes that the sequencelasted, the load factor varied between 1.96 g and -0.26 g, the pitch attitude reached13° nose-up and the angle of attack reached 10°. Altitude variations, however, wereless than 600 ft.


    I'm theorizing (not declaring) that the expedited climb was intentional, though probably more excessive than intended due to unpracticed skills.
    And I am theorizing it wasn't. Nobody knows what was in the pilot's mind but I see only 2 options.
    - He was in a mental state that he reacted irrationally, or
    - He lacked any minimum reasonable level of airmanship (meaning that he didn't understand AoA, stalls, and performance compromises at high altitude)

    And in any of these 2 situations, the moment that the AP disconnected, he lacked said airmanship. Either because he didn't bring it with him or because he lost it in that instance due to the mental state.

    It was a lack of proficiency on procedure. Memory procedures are meaningless if not committed to memory and practiced recurrently. Such procedures defend against erroneous improvisation.
    Aha! Lack of training! What other aspect of training where lacking? Stalls? High-altitude stalls? UAS? High-altitude UAS? Upset recovery? Manual flight? High altitude manual flight? Can we call the collection of those AIRMANSHIP?

    And I believe it was the lack of a simple, solid procedure that led him to improvise in this way. At that critical moment of surprise, his mind asked 'what do I do?' and, not finding an answer there, made one up based on prior concerns. It needed to find the correct answer there, which most likely would have been there if he had memory-procedure training for this.
    And I believe that a lack of an adequate procedure (shouldn't but) may explain why the situation was not handled flawlessly like in the sims sessions you see in YouTube. It may even explain a loss of control and even perhaps a crash. But NOT this 1.5G 12 deg 2500 ft 7000 fpm zoom climb. That, my friend, is lack of airmanship.

    I support your campaign for a better procedure, but I am not buying that the existence of the procedure, by itself, would have avoided AF447 (in the same way that the existence of a stall procedure didn't avoid that they stalled all the way from cruise altitude to the ocean)

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  3. #43
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    Hello? 2:10:49????
    They were doing 121 knots
    In a fully loaded A330
    Yes, the vertical speed was 1100 fpm, but it was "decreasing"
    Which means that they were at less that 1G (and hence lift was less that weight)
    And the stalled warning activated 2 frigging seconds after that.
    The moment that they increased the load factor to barely 1G.
    I see your point about load factor.

    You are looking at the invalid ISIS speed however:

    Quote Originally Posted by BEA Report
    At around 2 h 10 min 34, the speed displayed on the left side became valid again and was then 215 kt; the speed on the ISIS was still incorrect.
    Regaining 1G from 2:10:50 and the stall warning (approach to stall) required a significant (3/4 limit) pull and about a 1° rise in AoA. That is where I suspect the FD's played a role.

    But if you do climb, for whatever reason, you don't make a sustained unsustainable climb of 12 deg nose up and 7000 fpm. You have a goal in mind and my over-react, overshoot and oscillate towards that goal.
    Not ordinarily, not. This is from the 3rd Interim report:

    Quote Originally Posted by BEA Report
    The “Unreliable IAS” emergency manoeuvre requires as a first step to disconnect the automatic flight controls and disengage the Flight Directors. The two copilots had only been trained for the emergency manoeuvre at lower levels, in the course of which the pitch attitude to adopt is 10° or 15°.
    Regarding my theorized intention to climb to REC MAX, it does line up:

    At 1 h 52, the PF said to the captain “look, the REC MAX has changed to three seven five”

  4. #44
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    From the BEA:

    Case of TAM flight on 12 November 2003
    This case, which happened to an A330-200, was not one of the thirteen events studiedabove because no crew report was available. However, in the light of the data fromflight AF 447, it seems useful to mention it. In fact, following icing of at least twoPitot probes at FL360, the crew made some high amplitude flight control inputs (tothe stop), sometimes simultaneously. When the AP disengaged, both pilots madepitch-up inputs (one went to the stop) that resulted in an increase in pitch of 8°. Onseveral occasions, the stall warning was triggered due to the nose-up inputs, and thecrew reacted with strong pitch-down inputs. During the 4 minutes that the sequencelasted, the load factor varied between 1.96 g and -0.26 g, the pitch attitude reached13° nose-up and the angle of attack reached 10°. Altitude variations, however, wereless than 600 ft.
    How do you pull a 10° AoA at FL360 in an A330, and not stall?

  5. #45
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    You are looking at the invalid ISIS speed however:
    Yes, I saw that before your post and corrected it. By then you probably were already writing your post with the old version.

    Regarding my theorized intention to climb to REC MAX, it does line up:
    At 1 h 52, the PF said to the captain “look, the REC MAX has changed to three seven five”
    Yes, and at 2:00, just when the captain had left and the FP was briefing the new PM, that same person said:
    well the little bit of turbulence that you just saw we should find the same ahead we’re in the cloud layer unfortunately we can’t climb much for the moment because the temperature is falling more slowly than forecast So what we have is some REC MAX a little too low to get to three seven

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  6. #46
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    How do you pull a 10° AoA at FL360 in an A330, and not stall?
    Did yo read this part?

    On several occasions, the stall warning was triggered due to the nose-up inputs, and the crew reacted with strong pitch-down inputs.

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  7. #47
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    Regaining 1G from 2:10:50 and the stall warning (approach to stall) required a significant (3/4 limit) pull
    Actually not. The stall warning happened here in the red mark, with the stick almost neutral. The 3/4 nose-up pull is the crazy reaction of the pilot to the stall warning.

    Click image for larger version. 

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  8. #48
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    Did yo read this part?
    Not stall warning, I mean stall!

  9. #49
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    Not stall warning, I mean stall!
    I don't know what was the stall AoA for the conditions in this incident that BEA mentioned in the report of AF 447.
    I estimate that the critical AoA for the Air France stall at the top of the climb was about 11 degrees (see graph below)

    But in any event, how do you know that they didn't stall?

    The graph below is the 1st 15 seconds after the stall warning activated at the top of the climb in AF 447, and what I used to estimate the critical AoA (i.e. the AoA where the real stall occurs) in those conditions.

    Click image for larger version. 

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    Green = not stalled
    Yellow = on the verge of the stall, critical AoA
    Red: Stalled

    The key is the slope of the vertical speed (the slope of the vertical speed is the vertical acceleration).
    An increasing vertical speed means a lift > weight so there is some lift reserve.
    When you see that the AoA increases but the vertical speed decreases at the same time, that's a sign of a stall.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
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  10. #50
    Senior Member 3WE's Avatar
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    I see where Gabiee did a "comment-by-comment" reply several posts ago- here's mine:

    Quote Originally Posted by Evan View Post
    [Edited for brevity]I find it unreasonable that he lacked the most fundamental airmanship
    But he sure as hell seemed to demonstrate it...looks like a duck, walks like a duck and sounds like a duck...I won't make a 200% absolute statement, but...

    Quote Originally Posted by Evan
    I think he was executing what we might call an "emergency climb", probably trying to get the maximum possible climb rate. He pretty much did. The stall warning was momentary. Mostly he stayed within the edge of the performance envelope.
    1. This is highly consistent with a severe lack of fundamental knowledge- but go ahead, don't believe it.

    2. Fine- did he THINK he had normal law protections?

    3. Even with protections, a maximum performance climb is contrary to procedure and most fundamental concepts.

    Quote Originally Posted by Evan
    an attempt to arrest a false sink rate and 'regain' lost altitude,
    Fundamentally, you respond with measured and reasonable nose-up inputs...not MAXIMUM. A strong indication he lacked fundamental knowledge.

    Quote Originally Posted by Evan
    The "total freakout" seems to occur about a minute after the loss of autopilot. This, to me, is more mysterious.
    Indeed, it is mysterious.

    However, I maintain that even IF he changed his intent, he was addressing intent 1 with near incomprehensible violation of fundamentals and then changed to address intent 2 with near incomprehensible violations of fundamentals.

    Quote Originally Posted by Evan
    He had agreed to "go back down". Blah blah reduced pitch 6° ANU 216kts (different from 215 knots) AoA 5° blah blah blah 3000fpm 18° ANU pitch blah blah blah
    Nearly incompressible violations of fundamentals. I could be wrong, but I don't think 6 degrees ANU is quite how you get an A300 to do a FDnH descent. Seems he lacked fundamental knowledge, or was simply freaked out and using the stick as an oh-shit handle.

    Quote Originally Posted by Evan
    My only guess is that he was following the FD's which did suddenly reappear at that time and were giving instructions similar to his stick inputs.
    Blindly following FD directions to maintain a stall? The wonderful Airbus FD instructs you to pull up aggressively when you are stalled? If so, I'll give you a bad design. Still not interested in discrete procedures when maintain FDnH flight fundamentals would have been extremely adequate to not crash the plane.

    If the FD thing is true, then I'll also give you that Bonin's thought process changed from a fundamentally stupid freak out to thinking he is following an Evan procedure by using the FD. Still, for him to grossly violate the most basic fundamental rules that were in play...just doesn't reconcile that he was a solid fundamental airman.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  11. #51
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    How do you pull a 10° AoA at FL360 in an A330, and not stall?
    Your black-and-white, cant-see-the-forest-from-the-trees, disdain-for-fundamental-rules, incredible-addiction-to-type-specific-tidbits never ceases to amaze me.

    You don't stall an A330 at FL360 with 10-degree AOA the same way you don't stall an A320 at 5000 ft MSL at 10 degrees AOA, and (get this) the same way you don't stall a Cessna 172 400 feet AGL turning on to final with a 10-degree AOA.

    There's this fundamental rule that the vast majority of airfoils stall at an AOA very close to 16 degrees.

    Gabriel likes to envision an AOA indication that you monitor to keep things below 16 degrees.

    I have come to favor an indirect method of attention to airspeed and configuration (some special attention to bank) and back pressure and knowledge of times when folks have been known to botch it and stall by pulling up past 15 degrees AOA (the way in which you DO stall just about all airplanes at just about all airspeeds and attitudes).
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  12. #52
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Gabriel View Post
    Stalls? High-altitude stalls? UAS? High-altitude UAS? Upset recovery? Manual flight? High altitude manual flight?
    THE TREES

    Quote Originally Posted by Gabriel
    Can we call the collection of those AIRMANSHIP?
    THE FOREST

    And make no mistake- the trees are very important, but that does not make the forest less important.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  13. #53
    Senior Member Evan's Avatar
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    Quote Originally Posted by 3WE View Post
    Your black-and-white, cant-see-the-forest-from-the-trees, disdain-for-fundamental-rules, incredible-addiction-to-type-specific-tidbits never ceases to amaze me.

    You don't stall an A330 at FL360 with 10-degree AOA the same way you don't stall an A320 at 5000 ft MSL at 10 degrees AOA, and (get this) the same way you don't stall a Cessna 172 400 feet AGL turning on to final with a 10-degree AOA.

    There's this fundamental rule that the vast majority of airfoils stall at an AOA very close to 16 degrees.
    Well, another thing you might find amazing is the relationship between stall AoA and mach number.

    Perhaps you don't consider that a 'fundamental rule'. Your black-and-white, can't-see-the-A330-for-the-Cessna AoA rule needs some grey area.

    Amazingly, airplanes stall at a lower AoA at higher mach numbers.

  14. #54
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    Amazingly, airplanes stall at a lower AoA at higher mach numbers.
    Ok...link or it's not true. I need a graph or a chart that shows the critical AOA of an A330 vs speed which shows the critical AOA of 9 degrees up there zooming since 10 degrees apparently should cause a stall- and I ask Gabiee for a brief explanation, too.

    In any case, I seem to recall something about exercising care when doing an enthusiastic pull up and that at altitude- with another caveat that their stall speed buffer is reduced since the air is thinner, thus reduced lift capacity...

    No argument that a little high-altitude training might be in order for me, but I still see myself avoiding a stall because, in general, it's a bad idea to sharply haul back...it's called and accelerated stall...Good ole 172 stuff...

    A little finesse in your pull up and your speed will slow up a little and then the critical AOA becomes greater right?

    I dunno...pitch controls airspeed and you got a barber pole and lots of G's = extra degrees of AOA...awfully darn effective.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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