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

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  • Originally posted by Gabriel View Post

    The FlyDubai had a very strong change in pitch rate and a very strong reduction (inversion, in fact) of the normal acceleration. It looks to me that they could not miss the cue that the plane was pitching violently nose-down.
    You're both missing the point. This isn't about stealth, it's about disorientation. Yes, they will feel a change in orientation, but it may be an opposite sensation or a diminished one. And there seem to be quite a few variations on this. But have you read the Tatarstan crash report? That was certainly not a subtle change in pitch! Also...

    Originally posted by Gabriel
    That's 100 deg in 50 seconds (to make it easy), 2 degrees per second (if it was evenly distributed).
    It wasn't. I meant the entire event from go-around to impact took around 45 seconds. The pitch reversal took only about 5 seconds, judging from the plot.

    Comment


    • Originally posted by Evan View Post
      You're both missing the point. This isn't about stealth, it's about disorientation. Yes, they will feel a change in orientation, but it may be an opposite sensation or a diminished one. And there seem to be quite a few variations on this. But have you read the Tatarstan crash report? That was certainly not a subtle change in pitch! Also...
      No, am not missing your point. I understand that we both are talking not about missing the perception but misinterpreting it.

      Now are you talking about this?


      And this?
      Somatogravic illusion is a pitching illusion caused by the gravitational effects of acceleration combining with the earth's gravitational field to mislead the vestibular system's perception of spatial orientation.
      Or something different? (the "acceleration" in that quote, the one that causes a pitching illusion, I understand that is longitudinal acceleration).

      That's how all these illusions that I know off work.

      1) The body is quite sensible to:
      - The direction of the apparent gravity vector in 3D.
      - Rate of change of angular position in 3D.
      - Rate of change of acceleration in 3D.

      2) The body is somehow sensible to angular speed in 3D and to the absolute value of acceleration in 3D, but only in the short term and, and only if the angular speed is large enough.

      3) The body is absolutely insensible to angular position (what side is up or down).

      ("The body", in all of the above, excludes the eyes, which acts as a "calibrating" tool for angular position and angular speed, what in itself can cause its own illusions, like thinking that you are straight and level when the visible horizon is not flat due to clouds or mountains, or the famous case of increasing the descent rate when landing in poor visibility).

      --- 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


      • From MAK:

        "At a height of 900 m there was a simultaneous control column nose down input and stabilizer nose down deflection...the FDR recorded a nose down stabilizer input from the stabilizer trim switch of the control wheel lasting 12 seconds...as a result the aircraft, having climbed to about 1000 m, turned into descent with negative vertical acceleration of -1 g."

        Who could possibly hold the trim switch nose down for 12(!) seconds while experiencing negative one g???

        The possibility of the thing having jammed seems almost as high as the pilot holding it for that long?
        moving quickly in air

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        • It seems like a key thing would be to look at the control column position.

          If a trim runaway occurred for any reason, and the pilot(s) recognized it, the first instinct would be to move the column in the opposite direction, to keep pitch under control.

          If the control column was not moved to counter the trim change, I'd be inclined to think more that some sort of illusion like Evan describes was involved, or the act was intentional.
          Be alert! America needs more lerts.

          Eric Law

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          • Well, the control column was simultaneously pushed nose down it says, at least initially.
            moving quickly in air

            Comment


            • So that would mean the initial leaked information, claiming a stall and opposite control inputs by the two pilots is not correct. Also, the much discussed somatogravic/somatogyral illusion now seems very likely. And it's still pretty shocking in terms of pilot performance.

              Comment


              • It certainly seems to me like a pilot trying to pitch down an aircraft that he feels is not responding to his control column inputs. This sensation might have been enough to distract him from the AH. I wonder what is on the CVR. Twelve seconds of 'no comment'?

                Comment


                • Originally posted by Evan View Post
                  It certainly seems to me like a pilot trying to pitch down an aircraft that he feels is not responding to his control column inputs.
                  At -1g his whole body weight would be supported by his shoulder harness so I can't see how he can feel that the a/c is not responding? 12 seconds is a really long time.
                  moving quickly in air

                  Comment


                  • Originally posted by orangehuggy View Post
                    At -1g his whole body weight would be supported by his shoulder harness so I can't see how he can feel that the a/c is not responding? 12 seconds is a really long time.
                    It's happened before...

                    Comment


                    • Originally posted by orangehuggy View Post
                      Who could possibly hold the trim switch nose down for 12(!) seconds while experiencing negative one g???
                      a- Intnetionally (murdercide)
                      b- Unintentionally
                      ---b.1. He didn't realize that he was pushing the trim switch (it is under the thumb).
                      ---b.2. He was trying to disconnect the AP (either another thumb switch or an index finger switch).
                      c- He didn't: A short closed the trim switch circuit. For the FDR it would be impossible to tell.

                      --- 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


                      • Is it time for a reminder that we just might have to wait for the final report?

                        I still suspect it's some sort of mixture and chain of events of several $20.00 disorientations mixed with some loss of control, and perhaps CRM of the pilots having two different $20.00 disorientations, and some fatigue and the turbulence and something 'mechanical' may have broken and what Otto was doing vs. what someone THOUGHT Otto was doing...I'm not sure what the FCOM nor the fundamental rules say when you are diving into the ground at 200 MPH from 1000 feet meaning you have 3.409091 seconds to execute the memory checklist items for recovery.
                        Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                        Comment


                        • Originally posted by 3WE View Post
                          I'm not sure what the fundamental rules say when you are diving into the ground at 200 MPH from 1000 feet meaning you have 3.409091 seconds to execute the memory checklist items for recovery.
                          Hmmmm... Pull up?

                          --- 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
                            Hmmmm... Pull up?
                            With measured aggressiveness, or relentlessly?
                            Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                            Comment


                            • Originally posted by 3WE View Post
                              With measured aggressiveness, or relentlessly?
                              Below Va, as much as you want with the onset of the stickshaker as a limit,
                              Above Va, to 2.5G,

                              --- 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


                              • ...but do you agree that this incident is likely due to some other significant factors in addition to $20 disorientation?
                                Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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