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777 Crash and Fire at SFO

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  • Originally posted by agird View Post
    Boeingbobby, do you have anything of interest to add to this discussion?
    Everyone is entitled to an opinion, educated or not. Its also useful to have the opinion referenced with relevant experience or qualifications. Its then up to each individual to value that opinion as they see fit.

    This is the value of open forums, as a place to learn. Even if it is to learn about the relative misconceptions of others.

    As a dispatcher, I should have been fairly low down on the food chain, yet felt confident enough to question a senior Captain on more than one occasion on something that he was theoretically more qualified than myself.

    I've occasionally watched the pilot enter data from my loadsheet into the FMS and seen landing weight put in where take off weight should be, or similar. Some pilots are grateful for the support, others are furious of the presumption, even when they know they are wrong.

    I have often learnt more about my job and area of expertise from the 'ignorant' questions of my students. And so it is on a forum where someone of no intimate experience of being a pilot may voice an opinion about pilots, and someone with huge experience can quantify that opinion.

    Its all good, because a lot of us non-pilots are probably thinking the same about those pilots' performance while a lot of experienced pilots are probably thinking that its not as easy as people think.

    There are few jobs where minor, easliy made errors can end in such huge disasters.

    Comment


    • Originally posted by Evan View Post
      What do you make of that plot I posted earlier, especially that 600' drop below the glidepath? I'm thinking maybe it's related to A/P disconnect...

      EDIT: If that plot is at all accurate of course...
      I'm guessing that was about the time they lowered gear and/or full flaps?

      Comment


      • Some further interesting analysis here:

        Comment


        • Originally posted by Evan View Post
          What do you make of that plot I posted earlier, especially that 600' drop below the glidepath? I'm thinking maybe it's related to A/P disconnect...

          EDIT: If that plot is at all accurate of course...
          I don't know. It's very strange. The sudden 4000fpm looks almost impossible to me, especially since passengers reported everything normal until the final spool-up.

          The image that you posted is not very clear. It seems to say "Source: FlightAware.com", but it doesn't match this table also credited to FlighAware:

          11:26 37.5900 -122.3070 297° West 169 194 1,400 -1,380 FlightAware
          11:27 37.5988 -122.3270 299° West 145 167 800 -1,380 FlightAware
          11:27 37.6016 -122.3340 297° West 141 162 600 -1,320 FlightAware
          11:27 37.6045 -122.3410 298° West 134 154 400 -900 FlightAware
          11:27 37.6073 -122.3480 297° West 123 142 300 -840 FlightAware
          11:27 37.6103 -122.3550 298° West 109 125 100 -120 FlightAware
          11:28 37.6170 -122.3740 294° West 85 98 200 120 FlightAware

          --- 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
            Not only that, but apparently in this case the copilot was also, the Big Boss, the final authority, the one with the last word, the ultimate responsible for the safety of the flight, the highest link in the chain of command, or, in short, the PIC.


            I am famous for getting angry when these things happen and saying things like "Wasn't somebody supposed to be FLYING the plane? Didn't they note the speed decay in the Primary Flight Display, that has the words Primary and Flight in its name for a good reason?"

            However, since the error is not impossible, it WILL happen with a certain frequency depending on its likelihood.

            So even if you put a low likelihood, like the two pilots don't making this combined mistake in a 99.9999% of the cases, this leaves the opportunity for this incident to happen every 1 million flights. And does happen from time to time, sometimes with the fortune to happen a couple hundred feet higher to enable a recovery before hitting something.

            A study showed that in every flight there are mistakes. And several.
            Of course, the system is designed robust, so a human mistake doesn't down a plane in the vast majority of the cases. The mistakes are almost always detected by the offender, or by the other crewmember, or during a checklist, or by some airplane system (like the GPWS).

            In very few cases, the holes of the Swiss cheese will align to let an airplane fly through them to an accident. And as long as humans are part of the loop, these things will unavoidably keep happening.

            The key is to work to minimize the likelihood and hence the frequency not only of the mistakes themselves, but of them propagating to cause an accident.
            Looking at the plots and timeline in the link I just posted, it seems like this was clearly a case of a poorly stabilized approach, in which the pilot flying was high and fast, but allowed the aircraft to get ahead of him as he was correcting to get back to the right place, and unfortunately, no one on the flight deck noticed till it was much too late. It's a big mistake but as you say, these things will happen. People make mistakes all the time, this time it ended badly, the margin for this kind of error was gone. Probably most pilots can, and do, handle this approach without issues on a daily basis. But it definitely requires staying ahead of the airplane and anticipating what it will need to land normally.

            If anything, what this crash seems to illustrate most to me is just how quickly something more or less routine can go incredibly wrong during these critical phases of flight. This seems much less like the kind of gross negligence like in the case of the Turkish 738 in Amsterdam, where the guys had a long time without noticing, closed throttles, speed decaying, AND nose pitching up. In the case of flight 214 it seems everything happened relatively quickly and these guys just lapsed in staying ahead and on top of what was happening, at a critical moment when there was simply no room for that kind of error. A basic piloting failure, but I agree with Gabriel that this is something that can and will happen...

            Comment


            • Originally posted by Gabriel View Post
              The image that you posted is not very clear. It seems to say "Source: FlightAware.com", but it doesn't match this table also credited to FlighAware:
              I swiped it from the NY Times, and they cite Flightaware as their source for the data. Feel free to replot it (I know you will).

              NY Times reported today that they disconnected autopilot at 1600', which looks like it may coincide with that moment of high sink rate.

              If that plot is more or less accurate, one thing that comes to mind is that the PF saw that they were becoming high on the glide using automatics and took over the plane, overcontrolling and placing them well below it. (shades of that first link in the AF447 chain: the transistion...?)

              Comment


              • Originally posted by Gabriel View Post
                Ok, enough of that.

                BoeingBobby, could you please stop asking everyone about their qualifications to post their thoughts or opinions in this forum?

                This is an Internet forum, not a 747, so an ATP license is not required here.

                It would be much more constructive, in my opinion, if you criticized others based on what they said and not in their qualifications to say what they did.

                Thank you.
                I will do one better than that, I will leave you all to your ignorance.
                When I see what most of you write here, it is no better than the press.

                Enjoy

                Comment


                • Originally posted by BoeingBobby View Post
                  I will do one better than that, I will leave you all to your ignorance.
                  When I see what most of you write here, it is no better than the press.

                  Enjoy
                  I am sorry to hear that.

                  It is a privilege to have some professional pilots in this forum sharing their knowledge and discussing with people that comes from different fields of knowledge, have different qualifications, but share a common interest in aviation. And I was happy that you were one of them, even if I didn't like specifically your request for qualifications.

                  These forums are more a place for discussion than for one-way information. And typically the discussion, where someone says something, another one corrects them, another one doesn't agree, etc is much more informative and fun than a newspaper article. That's at least my personal view.

                  --- 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


                  • Being primarily a (long time inactive) glider driver with an SEL rating, I always appreciate the knowledge and comments of the pros, but I also like to parlor talk and speculate. We'd love to see you continue to contribute BB.

                    Comment


                    • Originally posted by Myndee View Post
                      Evan gets a welcome back, but I don't?
                      Welcome back Myndee

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                      • I've got a GRRREEEAAAT idea. How would if be if we were all to wait for the outcome of the NTSB report ( remember them, they're the true experts ? )


                        .......and then comment on that ?
                        If it 'ain't broken........ Don't try to mend it !

                        Comment


                        • Originally posted by Evan View Post
                          I swiped it from the NY Times, and they cite Flightaware as their source for the data. Feel free to replot it (I know you will).

                          NY Times reported today that they disconnected autopilot at 1600', which looks like it may coincide with that moment of high sink rate.

                          If that plot is more or less accurate, one thing that comes to mind is that the PF saw that they were becoming high on the glide using automatics and took over the plane, overcontrolling and placing them well below it. (shades of that first link in the AF447 chain: the transistion...?)
                          If you look at the two points of the segment of highest sink rate, they match exactly (in altitude) with the first two points of the other table:

                          11:26 37.5900 -122.3070 297° West 169 194 1,400 -1,380 FlightAware
                          11:27 37.5988 -122.3270 299° West 145 167 800 -1,380 FlightAware

                          Given the time elapsed between these two points as reported in your attachment (9 seconds) the sink rate was 4000fpm on average.

                          There is no time information in the table regarding how long it took to lose those 600ft (unless you accept the range "between 0 and 120 seconds" as "information"). But you have the ink rate for each point, and they are identical at 1380fmp. If the sink rate would have been constant at around that value between these two points, then the time between the two points would be about 26 seconds, not 9 as reported in your attachment.

                          So what's it? 1380 fpm during 26 seconds or 4000 fpm during 9 seconds?

                          There is a way to reconcile the info of both sources, and that's by dropping the assumption that the sink rate was constant in that segment. In other words, it was 1380 fpm at the beginning of the segment, then increased to a certain value (that necessarily will need to be well beyond 4000fpm), and then went back to 1380fpm.

                          This will not be nice for the passengers. Let's model it in the way that it's less violent, using a constant acceleration for the first half of the segment and the same constant acceleration (but in opposite direction) for the second half. So instead of making short, brisk accelerations we make them as smooth as possible by spreading them all along the 9 seconds.

                          That would have taken a constant push-down at 0.4G for 4.5 seconds immediately followed for a constant pull-up at 1.6G for another 4.5 seconds. The peek sink rate, in the middle of the segment, would have been 6600fpm.

                          We would know by now, from dozens of survivors saying that they thought they were going to die when the plane suddenly fell from the sky about one minute before the crash.

                          All this to say, I can't even attempt to derive any information from data that is very inconsistent to begin with.

                          --- 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 brianw999 View Post
                            I've got a GRRREEEAAAT idea. How would if be if we were all to wait for the outcome of the NTSB report ( remember them, they're the true experts ? )


                            .......and then comment on that ?
                            What fun would that be?

                            Comment


                            • Originally posted by Gabriel View Post
                              All this to say, I can't even attempt to derive any information from data that is very inconsistent to begin with.
                              So there is no way to establish the elapsed time between these points? I don't really understand from what source the information is received. Does it not come in regular time intervals? I assume it is datalink info and not radar returns. ACARS? VDL? ADS-B? Maybe you know?

                              While they do call it 'preliminary data', it is strange that the NY Times would state 9 seconds in a published infographic if there is no way to establish that. They typically are notorious fact-checkers on things like graphics. Perhaps they have worked with additional sources on this...

                              Comment


                              • Originally posted by Deadstick View Post
                                What fun would that be?
                                I agree with Deadstick too. That would take all the fun out of it .

                                Comment

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