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  • Originally posted by Northwester View Post
    No. If there is a proof that Russians in any way altered or falsified flight records, the whole report goes into garbage and you will eat your words without any conditions.
    If the FDR and/or CVR data is fabricated, all bets are off. That goes without saying. Currently, in lieu of any proof or even a distinct accusation of this, the data is considered to be legitimate. Unless the data is fabricated, even when additional data comes to light, it will be irrelevant unless it exonerates the crew from the errors and negligence revealed by the existing data.

    Example: if the PIC did indeed call for go-around at 100m, why is there no go-around (pitch, thrust, reconfiguration)?

    Comment


    • Originally posted by Northwester View Post
      Col. Grochowski, the vice-president of the Polish committee investigating the crash stated it today in a press interview.
      Polish experts from the Central Criminal Laboratory examined the tape and provided the information in December.
      Are the Russians confirming this as well?

      Comment


      • Originally posted by Evan View Post
        Are the Russians confirming this as well?
        Polish side informed Russians that they have data available to prove it. This info was included in Polish comments sent to Russia in December. No word from the Russians as far as I know.

        Comment


        • Originally posted by Northwester View Post
          Anyone familiar with engine work, in what conditions can you have N1 values go higher and at the same time airspeed decrease?
          It's not a matter of engine work, but of the Physics of the whole plane.

          The speed will decrease whenever the excess thrust is less than what is needed for steady flight at the actual climb rate.

          The excess thrust is simply thrust - drag. An increase in thrust alone will increase the excess thrust. An increase in drag alone will decrease the excess thrust.

          N1 going higher is a clear indication of increase in thrust.
          An increase in the angle of attack (such as in a pull-up) and clipping trees are good reasons for which the drag might increase.

          That's one part of the equation. Now that we have the excess thrust, we must work on the climb rate and airspeed.

          Excess thrust will always translate either in increase of speed or increase of altitude, or a combination of both. Not that any of the three (excess thrust, increase of speed, and increase of altitude) can be negative.

          For example, during the take-off run, all the excess thrust goes into increase of speed. During a climb at constant airspeed, all the excess thrust goes into increase of altitude. During cruise, the excess thrust is zero, the increase in speed is zero, and the increase of altitude is zero. If you then pull the throttles back to idle, the thrust goes down but since the drag remains the same, the excess thrust gets negative. If you keep the altitude, that negative excess of thrust translates into a negative increase of speed. On the other hand, if you lower the nose and maintain airspeed, the negative excess of thrust translates into a negative increase of altitude.

          But let's go back to the steady climb at constant airspeed and constant climb rate. In this case, the excess thrust is exactly the one needed for steady flight at that climb rate (re-read the beginning of this post). If you lower the nose a bit, the climb rate goes down and now the excess thrust is more than what's needed for this new climb rate (not because the excess thrust has changed, but because the new diminished climb rate requires less excess thrust for a steady flight). On the other hand, if you increase pitch a bit the climb rate goes up, but now your speed goes down because the excess thrust you have is less than what's required to hold a steady flight at the new increased climb rate.

          In short, if you increase thrust, you normally increase the excess thrust unless the drag increases more than the thrust. The new increased excess thrust will let you increase your climb rate (that can be read "diminish your descent rate" too), but only to some extent. If you increase your climb rate too much, your speed will still go down regardless the increased thrust.

          In this case, the increase in N1, was more or less simultaneous with the strong pull up (that according to the investigators would have led to a stall if they hadn't hit the trees) which would cause an increase in drag, with hitting trees that will cause more drag, and with the change of a pretty steep descent rate to a slight climb (which, peak to peak, is a high increase in climb rate net). Of course one would need to know the values of all these variables to calculate if the speed would increase or decrease in this specific situation.

          But it's not impossible that, in such conditions, the speed goes down with an increase in N1 and hence in thrust.

          All that said, after the first collisions with trees, I'd judge the airspeed indication unreliable due to possible damage/blockage that the Pitot tubes could have sustained, unless you have two independent measurements with consistent readings.

          --- 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 Northwester View Post
            Where did you get this information from? All dead within 0.1 sec after the impact?
            I stand corrected:

            - The Russians might have taken one hour to respond with the rescue. But chances are, by large, that the people on the plane was all dead 0.1 seconds after the final impact, and that no one could have been saved even if the best rescue and medical teams in the world were waiting for them at the scene of the accident.

            Happy now?
            I wasn't even thinking in the 0.1 seconds (I could have said 0.01 seconds or 1 second) and the 100 Gs. A plane crashed at 300 Km/h in a nose down attitude and inverted. That for me means everybody is instantly dead at the scene. The accident was not survivable. Have people survived non-survivable accidents in somehow exceptional a miraculous ways? Yes. But the chances are extremely low. And this one looks particularly (not marginally) non survivable.

            --- 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


            • I will stand somehow between Evan and Northwester.

              With the info we have, my view of the direct cause of the crash is that the pilots screwed up big time here, be it by intentionally busting minimums and doing so in a particularly stupid and unbelievable way, or because they were extremely unproficient and couldn't execute a go-around. Factors are that they were under a great pressure to make the landing, that they were very poorly trained and very poorly organized to operate this plane, the unstabilized approach and the violation of the sterile cockpit.

              Unless the Russians are fabricating the facts (something I that won't even consider unless there is factual evidence) nothing that the Russians could have made wrong will change this.

              AFAIK, even a military pilot in a military flight landing at a military airport in war time can NOT be ordered by the ATC not to execute a go-around if the pilot can't see the runway he is supposed to land on.

              All that said, the latest tendency is that the ultimate aim of an accident investigation is not find the causes but find weaknesses that can be fixed to prevent future accidents. Of course finding the causes is a good path, but there are others. For example, if an investigation finds that an engine was not serviced following the approved procedures, they must raise the point even if, in this particular accident, the plane hit a mountain with the engines working perfectly (i.e. even if the departure from the maintenance procedures was irrelevant to this accident).

              Between what caused an accident (read first paragraph) and other flaws completely unrelated to it (read previous paragraph) there is a spectrum of things, like things that didn't cause the accident but could have prevented it. For example (fictitious example), if the ATC had not told them about the actual conditions being below minimums, the accident should still not have happened because the crew should have gone around in a proper fashion, but the missing info could have made the crew not even attempt the landing in the first place and hence prevent the accident.

              In short, I doubt that my first paragraph will change much, but I want all the truth, not only the part that was in the direct chain of causation of the accident.

              The ATC did something wrong?
              The approach lights were not Ok?
              The emergency crew was not up to the task?
              All that had nothing to do with the outcome of this accident?
              Well, if not corrected, it might have to do with the outcome of the next accident.

              --- 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
                N1 going higher is a clear indication of increase in thrust.

                Excess thrust will always translate either in increase of speed or increase of altitude, or a combination of both. Not that any of the three (excess thrust, increase of speed, and increase of altitude) can be negative.
                Thank you for this exhaustive explanation. What I was thinking about was the moment right after the PIC says "go-around" at 10:40:41. Right before that someone says "100". Right after, at about 10:40:46 I see N1 values start increasing. The plane is at 100m altitude still descending. The speed is decreasing. If N1 values are increasing then we also have an increase of thrust. No change of angle of attack. But the altitude and speed are decreasing. How can that be explained?

                Comment


                • Originally posted by Northwester View Post
                  Thank you for this exhaustive explanation. What I was thinking about was the moment right after the PIC says "go-around" at 10:40:41. Right before that someone says "100". Right after, at about 10:40:46 I see N1 values start increasing. The plane is at 100m altitude still descending. The speed is decreasing. If N1 values are increasing then we also have an increase of thrust. No change of angle of attack. But the altitude and speed are decreasing. How can that be explained?
                  At this point the autothrottle is still engaged. The PF adds pitch, and therefore drag, so the autothrottle adds power (N1). I don't see a plot for AoA. The Indicated Air Speed drops momentarily, then levels off as thrust takes effect and remains steady until the autothrottle is disengaged by the actual go-around.

                  If you look closely at N1 plots, you will notice that during autothrottle engagement, the power fluctuates quite a bit more than with manual flight, as the computer is more active and precise in adjusting to power demands.

                  In this case, the PF added marginal pitch, then held it. The autothrottle added a marginal degree of power. It may have been enough to slow the rate of descent somewhat, but it was nowhere near the go-around requirement.

                  When the actual go-around happens (at the moment of the first tree strike), the autothrottle and AP both disengage as designed.

                  Comment


                  • Originally posted by Northwester View Post
                    Thank you for this exhaustive explanation. What I was thinking about was the moment right after the PIC says "go-around" at 10:40:41. Right before that someone says "100". Right after, at about 10:40:46 I see N1 values start increasing. The plane is at 100m altitude still descending. The speed is decreasing. If N1 values are increasing then we also have an increase of thrust. No change of angle of attack. But the altitude and speed are decreasing. How can that be explained?
                    Simply put, if the plane is steadily descending (constant speed, constant descent rate), and when the thrust is increased, the drag doesn't increase, the descent rate doesn't diminish, and the speed id decreasing, then call Newton. He's been wrong all this time.

                    Or to put it in other terms, if in a steady descent the thrust is increased and the speed goes down, either the drag increased more than the thrust or the descent rate diminished (or reverted) more than what the additional excess thrust can cope with. Any conclusion contradicting this is unavoidably wrong (or Newton is wrong).

                    Now, how this applies to this particular sequence of events, I don't know. To start with, you and Evan seem to be interpreting differently what the sequence of events really was to begin with, and I haven't done my own research as to contradict both of you .

                    --- 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


                    • Does anyone know if in the flight reconstruction from MAK that was posted on youtube, the indications on instruments (altimeters) were manually set by someone who created the video or fed directly from the FDR data?

                      Comment


                      • Originally posted by Northwester View Post
                        Have you seen all the chairs? If yes, then you must be one of the Russian investigators. No one else has seen full documentation from the crash scene.
                        You seem to be very selective in choosing your facts, rejecting those that do not support your theories young man.
                        First Polish experts arrived on the site on the evening of April 10th. The team of Polish investigators remained there until April 28th. By that time all the recording devices were recovered and the examination of the wreckage was no longer necessary.

                        Comment


                        • Originally posted by Evan View Post
                          A bit ghostly.

                          I'm certainly glad these aren't my tax dollars at work.
                          What's wrong with taking a jetliner for a spin on a nice sunny day? I would rather go my tax $$$ to that, than bailing our a corrupt and crooked banking system, not to mention automotive industry incapable of supporting itself.

                          Comment


                          • Originally posted by Peter_K View Post
                            You seem to be very selective in choosing your facts, rejecting those that do not support your theories young man.
                            First Polish experts arrived on the site on the evening of April 10th. The team of Polish investigators remained there until April 28th. By that time all the recording devices were recovered and the examination of the wreckage was no longer necessary.
                            So why would one of the main objections from Polish side be the refusal of Russian side to provide the documentation of the crash site from the day of the crash?

                            Comment


                            • Originally posted by Peter_K View Post
                              You seem to be very selective in choosing your facts, rejecting those that do not support your theories young man.
                              First Polish experts arrived on the site on the evening of April 10th. The team of Polish investigators remained there until April 28th. By that time all the recording devices were recovered and the examination of the wreckage was no longer necessary.
                              I don't know if you have noticed it, young man, but my theories change as new facts are revealed. I try to look at things that still require careful examination.

                              Comment


                              • Originally posted by Evan View Post
                                At this point the autothrottle is still engaged. The PF adds pitch, and therefore drag, so the autothrottle adds power (N1). I don't see a plot for AoA. The Indicated Air Speed drops momentarily, then levels off as thrust takes effect and remains steady until the autothrottle is disengaged by the actual go-around.

                                If you look closely at N1 plots, you will notice that during autothrottle engagement, the power fluctuates quite a bit more than with manual flight, as the computer is more active and precise in adjusting to power demands.

                                In this case, the PF added marginal pitch, then held it. The autothrottle added a marginal degree of power. It may have been enough to slow the rate of descent somewhat, but it was nowhere near the go-around requirement.

                                When the actual go-around happens (at the moment of the first tree strike), the autothrottle and AP both disengage as designed.
                                So to make sure I understood it correctly, you are saying that the increase of thrust was balanced by the increase of pitch, since both the speed (283 to 280) and altitude decreased in that time interval?

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