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Flydubai Flight 981 Crashes on Landing in Rostov-on-Don, Russia

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  • 2 comments:

    1- I have not seen them all, but I've never seen a single incident where pitch authority, including elevator and pitch trim, was not enough to keep pitch control. I did see a few cases where the plane went too slow, the trim went too nose-up, and then full thrust produced a pitch-up moment that cannot be counteracted with full nose-down elevator, but it could have been easily controlled by applying a bit of nose-down trim (I mean, reducing the nose-up trim). Only that this idea didn't crossed the pilots' minds.

    2- Because of the same reasons that I commented in previous posts, I doubt that somatogravic illusion played a big role here.

    --- 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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    • Originally posted by Gabriel View Post
      2 comments:

      1- I have not seen them all, but I've never seen a single incident where pitch authority, including elevator and pitch trim, was not enough to keep pitch control. I did see a few cases where the plane went too slow, the trim went too nose-up, and then full thrust produced a pitch-up moment that cannot be counteracted with full nose-down elevator, but it could have been easily controlled by applying a bit of nose-down trim (I mean, reducing the nose-up trim). Only that this idea didn't crossed the pilots' minds.

      2- Because of the same reasons that I commented in previous posts, I doubt that somatogravic illusion played a big role here.

      National Airlines Bagram Afghanistan Load shift! Just to name the last one, there are more.

      Comment


      • Originally posted by Gabriel View Post
        2 comments:

        1- I have not seen them all, but I've never seen a single incident where pitch authority, including elevator and pitch trim, was not enough to keep pitch control. I did see a few cases where the plane went too slow, the trim went too nose-up, and then full thrust produced a pitch-up moment that cannot be counteracted with full nose-down elevator, but it could have been easily controlled by applying a bit of nose-down trim (I mean, reducing the nose-up trim). Only that this idea didn't crossed the pilots' minds.
        Read that BEA report. One of the issues with modern jets is the lack of situational awareness on automated pitch trim. Certainly the effects of thrust can be overcome with BOTH elevator and pitch trim but pitch trim is the stealth factor that is often overlooked in these GA incidents. The report also addresses the high workload for the PM, who is often distracted from monitoring basic parameters and the 'tunnelling' effect of any unexpected event (i.e. excessive airspeed causing automated flap retraction) on the PF, also causing him to neglect the instrument scan and focus on only one parameter. There is even a footnote theorizing that, as the overspeed warning is coming from the top of the speed tape, this might cause a pilot under stress and fatigue to respond by pushing the column/sidestick forward to get away from it...

        Comment


        • Originally posted by BoeingBobby View Post
          National Airlines Bagram Afghanistan Load shift! Just to name the last one, there are more.
          Are you kidding? And how would reducing thrust have helped there? Did you read the post I was answering to?
          Ok, let me be more spoon-feed specific:

          I have not seen them all, but I've never seen a single incident where pitch authority, including elevator and pitch trim, was not enough to counteract the nose-up pitch moment induced by the increase of thrust in engines that are below the CG, an induced nose-up pitching moment that is very real and substantial (but not uncontrollable) when you go from a low thrust configuration to high thrust one, like when starting a go-around.

          --- 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


          • Originally posted by Evan View Post
            Read that BEA report. One of the issues with modern jets is the lack of situational awareness on automated pitch trim. Certainly the effects of thrust can be overcome with BOTH elevator and pitch trim but pitch trim is the stealth factor that is often overlooked in these GA incidents.
            So you prefer to teach to reduce thrust, in a situation where total energy is very low (low altitude and slow speed) and thrust is very much needed and welcomed, instead teaching to look at trim stealth factor? I mean, yes, the trim may have been stealthy moving, but the moment that you use full nose-down elevator and don't get a nose-down pitching, applying some nose-down trim should be the NATURAL reaction regardless of the pilot knowing or not what the trim had been doing before that point. And if it is not the NATURAL reaction, then something wrong is in the training, and it is not to reduce thrust.

            And I did read the BEA report.

            --- 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


            • Originally posted by Gabriel View Post
              ...the nose-up pitch moment induced by the increase of thrust in engines that are below the CG, an induced nose-up pitching moment that is very real and substantial (but not uncontrollable) when you go from a low thrust configuration to high thrust one, like when starting a go-around.
              And perhaps most importantly, an effect that should be expected by the pilots! Given that it occurs every time you increase thrust and there's a corresponding nose-down tendency every time thrust is decreased, anyone that's piloted such a plane for more than a few hours should be accustomed to it.
              Be alert! America needs more lerts.

              Eric Law

              Comment


              • Originally posted by Gabriel View Post
                So you prefer to teach to reduce thrust, in a situation where total energy is very low (low altitude and slow speed) and thrust is very much needed and welcomed, instead teaching to look at trim stealth factor? I mean, yes, the trim may have been stealthy moving, but the moment that you use full nose-down elevator and don't get a nose-down pitching, applying some nose-down trim should be the NATURAL reaction regardless of the pilot knowing or not what the trim had been doing before that point. And if it is not the NATURAL reaction, then something wrong is in the training, and it is not to reduce thrust.

                And I did read the BEA report.
                I prefer to teach both of course, but thrust management is probably the quickest to take effect and should probably be the first instinct when seconds are critical. But foremost, I prefer teaching pilots to not apply full GA thrust when a reduced thrust is both adequate and safer. And this is an AIRBUS problem because there are no go-buttons for reduced thrust; you have to apply the GA detent and then reduce it manually (the SOFT GA function on the newer busses tells me they recognized the problem there).

                Comment


                • What are we debating here- that Evan read a report that says that if you aren't careful, you can become complacent with SA and screw up after a LONG day flying in dark and stormy weather...

                  ...and then turned it into an overly-definitive, black-and-white-leaning statement?

                  ...and that Eric and Gabriel believe that the chain of events contains some additional significant contributing factors?
                  Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                  Comment


                  • Originally posted by Gabriel View Post
                    Are you kidding? And how would reducing thrust have helped there? Did you read the post I was answering to?
                    Ok, let me be more spoon-feed specific:

                    I have not seen them all, but I've never seen a single incident where pitch authority, including elevator and pitch trim, was not enough to counteract the nose-up pitch moment induced by the increase of thrust in engines that are below the CG, an induced nose-up pitching moment that is very real and substantial (but not uncontrollable) when you go from a low thrust configuration to high thrust one, like when starting a go-around.

                    Sorry, guilty of not reading the entire post. My bad.

                    Comment


                    • Originally posted by Gabriel View Post
                      So you prefer to teach to reduce thrust, in a situation where total energy is very low (low altitude and slow speed) and thrust is very much needed and welcomed, instead teaching to look at trim stealth factor?
                      They are also pointing out that, while thrust setting is readily available to SA, stabilizer position isn't. Now look at FlyDubai 981. Downward elevator and 12 seconds of downward pitch trim. The PF (probably due to disorientation) must have thought this was necessary but it seems like overcontrol to me. Did he know where the pitch trim was after that? HIs hand could tell him in an instant where the thrust was (LNP: 102%).

                      Comment


                      • Originally posted by Evan View Post
                        They are also pointing out that, while thrust setting is readily available to SA, stabilizer position isn't. Now look at FlyDubai 981. Downward elevator and 12 seconds of downward pitch trim. The PF (probably due to disorientation) must have thought this was necessary but it seems like overcontrol to me. Did he know where the pitch trim was after that? HIs hand could tell him in an instant where the thrust was (LNP: 102%).
                        Of course, even more obvious would be the position of the pitch...

                        I dare suggest that 1) pitch has priority over the pitch trim and 2) the trim should correct itself without the need for too complex of a list of procedures nor undue delay.
                        Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                        Comment


                        • Originally posted by BoeingBobby View Post
                          Sorry, guilty of not reading the entire post. My bad.
                          Ok but ensure that it doesn't happen again!!!

                          --- 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


                          • Originally posted by elaw View Post
                            And perhaps most importantly, an effect that should be expected by the pilots! Given that it occurs every time you increase thrust and there's a corresponding nose-down tendency every time thrust is decreased, anyone that's piloted such a plane for more than a few hours should be accustomed to it.
                            Of course, then we have the whole hand-flying vs. letting Otto do it and how "in practice" big-iron pilots are...I could see where it's kind of rare that you get to firewall the throttles after being all dirty and on an ILS and throw in some somatographology to the mix...

                            Maybe that one autopilot could provide some more help- just so long as someone looks at "the instruments" and sees that attitudes and airspeeds (and heading and altitude and VS and a few other nitpicky details) are healthy.
                            Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                            Comment


                            • Originally posted by 3WE View Post
                              Maybe that one autopilot could provide some more help- just so long as someone looks at "the instruments" and sees that attitudes and airspeeds (and heading and altitude and VS and a few other nitpicky details) are healthy.
                              If they did that. all they would need is the flight directors, which they would have when the autopilot disengages. At some point you are going to have to accept the realities of fatigue and stress and time compression and 'tunnelling' and vestibular disorientation and human factors and the importance of CRM and procedure and the danger of improvisation or you are never going to understand why these things happen. Most of these accidents are the result of hand-flying. But the hand can only do what the mind thinks is right. The autopilots don't have this problem, so use em if you've got em.

                              Comment


                              • Originally posted by Evan View Post
                                Most of these accidents are the result of hand-flying. But the hand can only do what the mind thinks is right. The autopilots don't have this problem, so use em if you've got em.
                                ... which is probably what the pilots of AF447 were thinking...
                                Be alert! America needs more lerts.

                                Eric Law

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