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Air France Off the Hook on AF447

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  • #46
    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.

    --- 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 ---

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    • #47
      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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      --- 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 ---

      Comment


      • #48
        Originally posted by Gabriel View Post
        Did yo read this part?
        Not stall warning, I mean stall!

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        • #49
          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. ---
          --- Defend what you say with arguments, not by imposing your credentials ---

          Comment


          • #50
            I see where Gabiee did a "comment-by-comment" reply several posts ago- here's mine:

            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...

            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.

            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.

            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.

            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.

            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.

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            • #51
              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.

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              • #52
                Originally posted by Gabriel View Post
                Stalls? High-altitude stalls? UAS? High-altitude UAS? Upset recovery? Manual flight? High altitude manual flight?
                THE TREES

                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.

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                • #53
                  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.

                  Comment


                  • #54
                    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.

                    Comment


                    • #55
                      Originally posted by 3WE View Post
                      Ok...link or it's not true.
                      https://lmgtfy.com/?q=AoA+and+mach+number

                      You know 3WE, you may have solved the mystery of the ignored stall warnings. If Pierre Bonin had your confident grasp of fundamentals**, learned in the early stages of flight training on a Cessna 172 (or a Tomahawk) and if he, like you, never received training on compressibility effects related to mach and how they alter the stall AoA, and if he, like you, believed that the stall AoA was immutable for a given airfoil, he might have assumed that 6-10 deg of pitch was perfectly safe.

                      Consider this:

                      - His hand flying skills, in climb, were probably almost exclusively in rotating off the runway and getting up to autopilot engagement, and, at any rate, in the low speed regime. A rotation pitch input would be around 8-10 deg on the A330-220, I think (maybe even a bit more) at a rate of about 3 deg/second.
                      - The sidestick input for rotation is about 3/4 of stick limit.
                      - If that pitch input didn't risk stall on rotation, and he didn't understand the relationship between stall AoA and mach, he might have reasoned that it was certainly safe at twice the rotation speed.
                      - The two initial stall warnings occur at 3 deg and 6 deg pitch. Without an understanding of the mach/AoA relationship, using 'fundamental rules' from basic airmanship lessons, that would certainly seem like a false stall warning.

                      I think you might have solved this one.

                      ** Of course, 3WE would never have pulled up in the first place, even if his head was filled with the desire to do so and he was caught by surprise and somewhat panicked.

                      Comment


                      • #56
                        Originally posted by Evan View Post
                        Consider this:

                        - His hand flying skills, in climb, were probably almost exclusively in rotating off the runway and getting up to autopilot engagement, and, at any rate, in the low speed regime. A rotation pitch input would be around 8-10 deg on the A330-220, I think (maybe even a bit more) at a rate of about 3 deg/second.
                        - The sidestick input for rotation is about 3/4 of stick limit.
                        - If that pitch input didn't risk stall on rotation, and he didn't understand the relationship between stall AoA and mach, he might have reasoned that it was certainly safe at twice the rotation speed.
                        - The two initial stall warnings occur at 3 deg and 6 deg pitch. Without an understanding of the mach/AoA relationship, using 'fundamental rules' from basic airmanship lessons, that would certainly seem like a false stall warning.

                        I think you might have solved this one.
                        Yep. That description matches "lack of airmanship".

                        He was an A330 pilot. If he believed that he could execute a cruise climb at M 0.8 and FL350 in the same way that he rotates at take-off, that's lack of airmnaship.


                        ** Of course, 3WE would never have pulled up in the first place, even if his head was filled with the desire to do so and he was caught by surprise and somewhat panicked.
                        Now, I can forgive 3WE not being familiar with the compressibility effects associated with the high altitude flight. But that's unforgivable for an ATP flying a A330 (of for whomever educated him).

                        And, I strongly suspect that, even if 3WE had pulled up and stalled the plane because he thought he had more useful AoA available, he would not have kept doing essentially pull-up inputs once the stall warning goes off.

                        --- 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 ---

                        Comment


                        • #57
                          Originally posted by Gabriel View Post
                          Yep. That description matches "lack of airmanship".
                          Yes, but is that a lack of "basic universal airmanship that you learn in the 172? No, it isn't. Did they teach you about mach issues in flight training for the Tomahawk, or did you learn it on your own?

                          Now, I can forgive 3WE not being familiar with the compressibility effects associated with the high altitude flight. But that's unforgivable for an ATP flying a A330 (of for whomever educated him).
                          Or failed to educate him. And how many others like him? That's all I care about here. Since transport pilots so rarely hand fly at higher mach, and even more rarely maneuver in this regime, the lapse of knowledge wouldn't ordinarily be an issue and wouldn't reveal itself. Perhaps it did with AF447.

                          The report came to no such conclusion. No recommendations were made to ensure that the effects of compressibility are taught to transitioning pilots. Did they overlook this possibility?

                          The complexities of AoA are addressed in AERO 12. This is a magazine oriented towards operational line pilots, providing supplemental knowledge. If pilots don't learn this is basic flight training, how reliably are they learning this in transition training?

                          http://www.boeing.com/commercial/aer...ack_story.html

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                          • #58
                            Originally posted by Evan View Post
                            Originally posted by Gabriel
                            Yep. That description matches "lack of airmanship".
                            Yes, but is that a lack of "basic universal airmanship that you learn in the 172? No, it isn't. Did they teach you about mach issues in flight training for the Tomahawk, or did you learn it on your own?
                            If you leave out the 99% irrelevant issue of Mach/compressibility, this is totally "basic airmanship".

                            Pretty much every airplane ever made, from the Cub to the A380 has an altitude above which it will not climb, at any given atmospheric condition and weight. Just below that altitude, it climbs really badly. Farther down in the atmosphere, it will climb better.

                            And therefore in pretty much every airplane ever made, the closer it gets to its altitude limit, the less you can try to make it climb without bad things happening. I learned this in ground school and experienced it within the first few hours of flying the 172. I'm sure the AF pilots had a similar experience.
                            Be alert! America needs more lerts.

                            Eric Law

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                            • #59
                              Originally posted by elaw View Post
                              Pretty much every airplane ever made, from the Cub to the A380 has an altitude above which it will not climb, at any given atmospheric condition and weight. Just below that altitude, it climbs really badly. Farther down in the atmosphere, it will climb better.
                              Because, further down is something called REC MAX, which apparently you can climb to at just under 7000fpm it you really push it to the edge.

                              Comment


                              • #60
                                Originally posted by Evan View Post
                                You know 3WE, you may have solved the mystery of the ignored stall warnings. If Pierre Bonin had your confident grasp of fundamentals...
                                That is just about 100% flawed logic AND you have a huge comprehension problem.

                                "Be careful when pulling up aggressively and pay attention to stall warnings".

                                I have never ever not paid attention to stall warnings.

                                I have 'failed' to address them when executing deliberate practice stalls (following the procedure of 3000 ft AGL and 180 degrees worth of clearing turns staring intently downward)- and failed to address them when trying to execute the elusive full-stall-squeaker landing. (Pretty fundamental stuff there).

                                As we have said about 15 billion times, Bonin was following a reasonably good, accepted, reliable and uber-basic procedure for how TO deliberately stall almost all aeroplanes.

                                Doesn't matter one flying phugoid what the critical AOA is...the fundamentals apply...pull up using your brain and your ears to listen for stall warnings, and your buttocks to sense wing loading (hell, maybe even glance at Gabiee's AoA gauge if you think you need to).

                                Originally posted by Gabieee
                                And, I strongly suspect that, even if 3WE had pulled up and stalled the plane because he thought he had more useful AoA available, he would not have kept doing essentially pull-up inputs once the stall warning goes off.
                                A little disconcurment: 3BS would NOT be THINKING he had lots of useful AoA available...As Eric described- 3BS having some super basic fundamentals knows that when at 35,000 feet ish, you are in thin air and at least somewhat near the ends of the performance and with hints of coffin corner...

                                Don't do too much radical, lest you break up and die (which CAN happen (no blue font) in an indirect fashion).

                                But thank you for the slight acknowledgement that I don't think I would have pulled up the whole time while wallowing into the ocean with British Bitching Brian saying "Stoll...Stoll" EITHER.
                                Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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