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

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  • Originally posted by Evan View Post
    Still seems to me a high probability that somatogravic illusion was behind this.
    Disagree (with the high probability part)...

    After an assumed somewhat stable climb to 3000 feet, your inner ear and buttocks are tricked into initiating a seriously hellacious extremely steep dive for 3000 feet? "high probability"???

    Yeah, sure, in the moments surrounding the actual transition to the go around, a brief moment of disorientation causing a more gentle descent (in an environment with little margin)...Okay...but for two airline pilots and lots of bells and whistles and flat screen TVs, and AFTER a minute of "stable" climb out time "established" on instruments...

    ...this isn't JFK single pilot and a 6-pack of nasty steam gauges.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

    Comment


    • Originally posted by Gabriel View Post
      http://avherald.com/h?article=495997e2&opt=0



      All seems perfectly normal until the underlined part.
      So say they they wanted to level off at 3000ft, they applied nose-down trim to level off and ___________________.
      Got out my Excel spreadsheet to do some trigonometry.

      720 feet would put them 2.6 miles from the "TDZE" and coincidental crash site, assuming they were pretty much on the glideslope.

      After the go-around they would have to average about 2500 fpm of climb and then almost instantly get into a vertical dive.

      My point being that I tend to doubt that things were "perfectly normal" until the push over.

      OR, in 2.6 miles can you take a 737 from 720 feet to 3330 feet and then back down to zero feet without some serious maneuvers going up as well as going down?

      Man, I should make a graph so I can be called Ardvark2zz...

      Something probably had to be amiss before then...

      Possibly an extra steep climb out to achieve the 3000 ft height

      and/or

      An early go-around from a position significantly below the glideslope.

      Important disclaimer- I have no more proof that his must be than Evan has proof of $20word disorientation theory...but I will say that there's some likelihood that something was wrong before the dive (short of a crazy wind gust trashing the horizontal stabilizers/crazy structural failure/elevator servo reversal sorta like the rudder actuator deal/etc.).
      Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

      Comment


      • I don't even think a "6-pack of nasty steam gauges" is an excuse.

        Any instrument-rated pilot that's worth his salt, and particularly an ATP, should be able to look at this guy here:

        ...and if the position of the pointer doesn't agree with what his body's balance system is telling him, recognize what's going on and take proper corrective action.

        That's not to say that humans never make mistakes, but the above is a pretty fundamental part of being an instrument pilot.
        Be alert! America needs more lerts.

        Eric Law

        Comment


        • So looking at the current "body of evidence", much of which comes from not-entirely-reliable and/or not-entirely-conclusive sources, we have:

          1. Aircraft attempts an approach to land.
          2. At a point a few moments prior to touchdown, the crew decides to go around.
          3. Initiation of go-around appears normal, aircraft climbs.
          4. Aircraft then noses over and dives steeply into the ground.
          5. Indications are that #4 is not due to "technical malfunction of engines or aircraft systems or...an explosion".

          At first it seems possible there could be a "technical malfunction" of something other than the engines or aircraft systems... wing icing, freak windshear? But the text Gabriel quoted states "the stabilizer moved nose down causing the aircraft to stop climbing...and entering a descent." The way I read that is that the change from climb to dive was caused by the stabilizer motion and not the other way around, ie the aircraft begins to stall and the yoke is pushed forward to recover.

          So IMHO what's left is pilot action: either unintentional or intentional.
          Be alert! America needs more lerts.

          Eric Law

          Comment


          • Originally posted by 3WE View Post
            Disagree (with the high probability part)...

            After an assumed somewhat stable climb to 3000 feet, your inner ear and buttocks are tricked into initiating a seriously hellacious extremely steep dive for 3000 feet? "high probability"???
            You should do your homework on somatogravic and somatogyric issues affecting pilot vestibular perception. A lot has to do with rapid changes in attitude or speed. The most pertinent one here is what is called 'inversion illusion':
            An abrupt change from climb to straight-and-level flight can stimulate the otolith organs enough to create the illusion of tumbling backwards, or inversion illusion. The disoriented pilot may push the aircraft abruptly into a nose-low attitude, possibly intensifying this illusion.
            So, to speculate in this instance, a manual go-around could have been done with full TOGA thrust and an aggressive pitch rate. The excessive thrust would exacerbate the pitch rate and result in a steep rate of climb (though there is no mention of stall warning from the investigation, so still within the AoA envelope). An abrupt level-off at 3000' may have produced the inversion illusion as resulted in a commanded steep downward pitch that the crew believed was still pitching upward.

            Now, for this to happen, a number of things need to contribute. It has to be IMC. The instruments need to be ignored or doubted and the senses trusted completely.

            The human factors of fatigue, procedural deficiency, complacency and confirmation bias make this scenario possible in IMC.

            And lastly, it has happened before and, at least at FlyDubai, it seems nothing was done to prevent it from happening again.

            The latest report claims there were no mechanical failures of system issues. If this was a case of runaway trim or some other mechanical issue, I don't think the latest report would fail to mention it. There is also no mention of windshear alert on the CVR. So I'm leaning towards pilot error. Why would a flight crew fly a perfectly good airplane into the ground? See the above...

            Comment


            • Originally posted by Evan View Post
              ...You should do your homework...
              Thanks for that comment and additional $20 words.

              The reason I say that is that Eric's photo of the VSI REALLY REALLY hit home.

              You see, I've spent a few hours guiding a 172 with the attitude indicator covered over...using the ASI as a pitch indicator.

              During those hours (including a lot of acceleration and deceleration in both lateral and vertical directions) and, including an exercise called "recovery from unusual attitudes", I never felt an overwhelming feeling to initiate a straight down dive...(a rather absolute statement and I guess there's always a first time, but...)

              (I did once bank left to 30 degrees from 20 degrees when I should have banked right back to zero, but the fundamental rule "DON'T sit there continuing to use a control input WITHOUT checking your instruments" saved me).

              So, there's a few hours of some fairly relevant homework...and unless your engineer buddies forgot to put "look at the instruments" in the FCOM procedure on how to level off a 737-8 after initiating a go-around with only one autopilot turned on in a 15 MPH surface crosswind component, I'm thinking these guys were peeking at the instruments- including the equivalent flat-panel read out of the thing that Eric posted a couple posts back up.

              As I stated above, I will give you a brief disorientation at the moment of go-around and right after cloud entry, (like what has happened before).

              But to restate- 1. after a minute...2. TWO WELL TRAINED PILOTS...3. in a big fancy airplane...4. to initiate a near-vertical dive...Unlikely + Unlikely + Unlikely + Unlikely.

              That's versus falling out of the clouds almost immediately after a go around initiation in something less than a vertical dive...Also unlikely, but much more likely than your scenario...

              ...but please, continue with your "high probability" argument and $20 words.
              Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

              Comment


              • Originally posted by 3WE View Post

                But to restate- 1. after a minute...2. TWO WELL TRAINED PILOTS...3. in a big fancy airplane...4. to initiate a near-vertical dive...Unlikely + Unlikely + Unlikely + Unlikely
                Yes, yes, never happened to you in a Cesnna so you call doing your that homework...
                Tatarstan Airlines Flight 363

                https://en.wikipedia.org/wiki/Tatars...nes_Flight_363

                Comment


                • Fixed.

                  Originally posted by elaw View Post
                  I don't even think a "6-pack of nasty steam gauges" is an excuse.

                  Any instrument-rated pilot that's worth his salt, and particularly an ATP, should be able to look at this guy here:

                  ...and if the position of the pointer doesn't agree with what his body's balance system is telling him, recognize what's going on and take proper corrective action.

                  That's not to say that humans never make mistakes, but the above is a pretty fundamental part of being an instrument pilot.

                  --- 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 3WE View Post
                    Got out my Excel spreadsheet to do some trigonometry.

                    720 feet would put them 2.6 miles from the "TDZE" and coincidental crash site, assuming they were pretty much on the glideslope.

                    After the go-around they would have to average about 2500 fpm of climb and then almost instantly get into a vertical dive.

                    My point being that I tend to doubt that things were "perfectly normal" until the push over.

                    OR, in 2.6 miles can you take a 737 from 720 feet to 3330 feet and then back down to zero feet without some serious maneuvers going up as well as going down?

                    Man, I should make a graph so I can be called Ardvark2zz...

                    Something probably had to be amiss before then...

                    Possibly an extra steep climb out to achieve the 3000 ft height

                    and/or

                    An early go-around from a position significantly below the glideslope.

                    Important disclaimer- I have no more proof that his must be than Evan has proof of $20word disorientation theory...but I will say that there's some likelihood that something was wrong before the dive (short of a crazy wind gust trashing the horizontal stabilizers/crazy structural failure/elevator servo reversal sorta like the rudder actuator deal/etc.).
                    You are making good points. But keep in mind that a 737 can (and do) climb quite better than 2500fpm, especially if somehow low on fuel after the trip and 2.5 hours holding. So please go to your Excel and enter 3500 fpm. How short of the vertical of the TDZ would it have achieved 3000ft?

                    --- 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
                      The latest report claims there were no mechanical failures of system issues. If this was a case of runaway trim or some other mechanical issue, I don't think the latest report would fail to mention it. There is also no mention of windshear alert on the CVR. So I'm leaning towards pilot error. Why would a flight crew fly a perfectly good airplane into the ground? See the above...
                      Not exactly. The report says that preliminary analysis of the CVR and FDR reveals no evidence of mechanical failure. A mechanical failure could have existed but no evidence was revealed in this preliminary analysis. And a trim runaway is a good candidate for a stealthy failure (hard to tell if it was commanded or not).

                      That said, I tend to think that it was commanded. So I am also leaning towards pilot error (as I have been leaning since I saw the video of the approach, go around, dive, crash).

                      --- 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 3WE View Post
                        But to restate- 1. after a minute...2. TWO WELL TRAINED PILOTS...3. in a big fancy airplane...4. to initiate a near-vertical dive...Unlikely + Unlikely + Unlikely + Unlikely.
                        Yes, that's why it doesn't happen often. Something very unlikely will eventually happen if you try enough times.

                        --- 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 in response to Eric's VSI
                          Fixed.
                          No...I agree with elaw.

                          The gauge you show is hooked to crappy vacuum pumps built with cheap composite air vanes that are brittle and break with great frequency, leading to sooo many light plane crashes that Evan would really freak out if he cared about such cowboy affairs.

                          The gauge Eric shows is generally only affected by static port obstructions- often contains a backup by-pass static port AND has a double backup of breaking the glass (but not pulling the fire alarm).

                          Eric's gauge is your primary pitch indicator for when your gauge breaks...

                          I stand as proof that one does not need to be a super genius to use Eric's gauge to maintain pitch...small, careful inputs, followed by checking the instruments (I found it to work on the 172/MSFS as well as the 172P genuine non-composite-metallic models.)

                          In fact, I think the bold sentence fragment above is another one of those totally undisciplined cowboy things, not on Evan's checklists, that would nonetheless help one from putting a 737 into a 3000 ft vertical dive.
                          Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                          Comment


                          • Originally posted by Gabriel View Post
                            You are making good points...
                            Thank you for your acknowledgement that it's not a lot of time to go from seemingly OK flight at 700 feet to 3000 feet and then to a crazy dive to zero feet.

                            To do your additional, requested calculations, what ground speed do you want me to use? (Give me a SWAG based on surface wind + winds aloft being higher and possibly a slightly different heading)
                            Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                            Comment


                            • Originally posted by 3WE View Post
                              The gauge you show is hooked to crappy vacuum pumps built with cheap composite air vanes that are brittle and break with great frequency, leading to sooo many light plane crashes that Evan would really freak out if he cared about such cowboy affairs.
                              True. Its relatives in the 737 NGs are triplets, none of which is fed by a vacuum pump, all of which are fed by a multitude of electric systems each with multiple redundant power source, and one of them just in case has an additional standby battery and will still working if all the sources of all the electric systems go West. Plus, at least 2 of them have no mechanical parts whatsoever (except for the mounting screws). That's why, while the vacuum artificial horizons in general aviation have failed in mass, the failures of the videogame-like ones in modern airliners (or in modern Cessnas 172) have very seldom failed, let alone several of them at the same time.

                              --- 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 3WE View Post
                                Thank you for your acknowledgement that it's not a lot of time to go from seemingly OK flight at 700 feet to 3000 feet and then to a crazy dive to zero feet.

                                To do your additional, requested calculations, what ground speed do you want me to use? (Give me a SWAG based on surface wind + winds aloft being higher and possibly a slightly different heading)
                                The same one that you used for your previous calculation: 160 kts.

                                --- 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

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