Announcement

Collapse
No announcement yet.

A380 Rudder Reversals

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #31
    Originally posted by Gabriel View Post
    At what point? How much would you bank 1 or 2 seconds before touchdown?
    Just til I head the scrapy sound.

    Com'on Gabriel, you've never seen bank used in a crosswing landing?

    Comment


    • #32
      Originally posted by Evan View Post
      Just til I head the scrapy sound.

      Com'on Gabriel, you've never seen bank used in a crosswing landing?
      Evan, you are not reading my posts. How much bank would you apply 2 seconds before touchdown? I am sure that between zero as you pretend that I am implying and the scrapy sound there is some range. How much would the plane even bank if you start banking 2 seconds before touchdown? How much would the airplane turn left at that bank and in that time? (or will you keep the plane banked after touchdown?). The nose was aiming right, The plane was to the right of the threshold and moving more and more to the right. What do you do? Do you really believe that 2 seconds of bank would have been enough?

      Anyway, I would say that they should have banked a bit. Hell, I would not say. I DID say it a few posts ago, those that you are not reading, but I very much doubt that that alone would have kept the plane from going off the side of the runway. For me the not-so-good piloting comes AFTER the touchdown, when the pilot enters that series of pilot-induced oscillations with rudder reversals. Up to after the touchdown, there was no clear or significant rudder reversal.

      Originally posted by Evan View Post
      Com'on Gabriel, you've never seen bank used in a crosswing landing?
      Yes, and typically into the wind, which in this case would be to the right.

      --- 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


      • #33
        Originally posted by Gabriel View Post
        Evan, you are not reading my posts. How much bank would you apply 2 seconds before touchdown? I am sure that between zero as you pretend that I am implying and the scrapy sound there is some range. How much would the plane even bank if you start banking 2 seconds before touchdown? How much would the airplane turn left at that bank and in that time? (or will you keep the plane banked after touchdown?). The nose was aiming right, The plane was to the right of the threshold and moving more and more to the right. What do you do? Do you really believe that 2 seconds of bank would have been enough?

        Anyway, I would say that they should have banked a bit. Hell, I would not say. I DID say it a few posts ago, those that you are not reading, but I very much doubt that that alone would have kept the plane from going off the side of the runway. For me the not-so-good piloting comes AFTER the touchdown, when the pilot enters that series of pilot-induced oscillations with rudder reversals. Up to after the touchdown, there was no clear or significant rudder reversal.


        Yes, and typically into the wind, which in this case would be to the right.
        The thing is, I'm not a pilot and I never pretended to be one so I'm not going to get into an argument over the AMOUNT of control input that is needed. I am concerned here with the NATURE of the control input. I concentrate on what is learned in accident reports and what needs to be altered or improved on to make flying safer. What I see on this video appears to be a pilot using rudder too actively, applying too much rudder, for too long, in opposite directions and it results to an upset situation. That leads me to think that this pilot has insufficient ON TYPE motor skills training on rudder and/or has incorrect technique training on the use of rudder ON TYPE and/or was caught in a moment of aircraft-pilot coupling. I think it really deserves attention and hopefully the airline noticed this as well.

        The pilot who broke AA587 and killed all those on board had a history of aggressive rudder use. The report documents two occasions where the pilot was counseled by his flight captain for this behavior, The trouble is, nobody took it very seriously, nobody saw where it could lead to. Since that report came out, pilots have been given greater awareness of the role and use of rudder on large aircraft and the potential dangers and training programs have been modified to distinguish recovery techniques by type of aircraft. That's great. But how many pilots are still not getting this training? All it takes is one and some uncommonly bad luck.

        What do you do?
        In this case, it appears to me that the pilot is using rudder very actively as a primary control surface, the way you would in a much different, much smaller aircraft, and I don't think it was necessary. And if he was in danger of departing too far from the centerline with only some bank and more-or-less neutral rudder—without cranking over that much rudder for that long to align (and subsequently touch down with that much yaw rate), then I think that is reason to arrest it and go around.

        Comment


        • #34
          -
          Originally posted by Evan View Post
          WIth a fin of that magnitude, do you really need reversals to get things centered?
          Get over your reversal obsession. A little back and forth is normal (and ok, sometimes it looks impressive and full ish). 'A fin of that magnitude' needs the same relative swings as any other plane... the fin is big because the plane is big. The big fin dosn't make it more controllable, the big fin assures that it's properly controllable. Again... watch some other crosswind YouTubes, note the rudder deflection which is often visible. The rudder goes back and forth, as necessary, to address yaw. Get out of the bubble and drive your car in a crosswind. Note that you will move the steering wheel back and forth as-necessary.

          Plus, it's kind of hard to bust off a tailfin when a plane is full flaps slow. You really have to hit it just right and a bit faster.
          Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

          Comment


          • #35
            Originally posted by Evan View Post
            1. I am concerned here with the NATURE of the control input. I concentrate on what is learned in accident reports and what needs to be altered or improved on to make flying safer.

            2. In this case, it appears to me that the pilot is using rudder very actively as a primary control surface, the way you would in a much different, much smaller aircraft, and I don't think it was necessary.
            1. Sorry man... the deal is that you do those things with an exceedingly strong, black and white mentality... yes, really...and again, this one is on you, and not an excuse to play with my voodoo doll.

            2.

            A. The rudder is ALWAYS a primarily control surface. (say that 1000 times) Its nice that the yaw damper works it most of the time, but pilots are expected to make inputs during crosswind landings and when in the runway.

            B. Reread your own wing scrape comment-a beautiful combination of sarcasm and accuracy- that means you don't have much bank availability and must instead depend on rudder...

            C1. Down low..,
            And
            C2. In a crosswind...

            The rudder IS your primary directional control (see footnote).

            Does he use it too much in your opinion...(Read Gabriel's comment about running off the side of the runway). It's the black and white tone...he used the rudder too much, he's an idiot, training is all wrong, what I would have done...yeah, you don't say exactly that, but the tone is pretty clear.

            Was it less than genius rudder use?...perhaps so...but YouTube is full of not-so-pretty crosswind landings, and Gabriel and I and Bobby and ATL will testify that it is something of an art a skill to make the perfect inputs as you force the plane to fly in an uncoordinated manner to land on a somewhat narrow strip of concrete and with changing winds...there will be imperfections.

            Footnote: Ironingly, a high wing Cessna allows liberal use of bank for directional control... so the 'big planes are different from little ones' argument you always make... yeah, you need MORE rudder to steer the big one in a crosswind.
            Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

            Comment


            • #36
              Originally posted by Gabriel View Post
              ***Then, immediately before and during touchdown, the pilot applies what seems to be a full travel and somehow long left rudder input.***
              When I look at this, I also note that the plane is somewhat to the right of centerline, and maybe a bit slow to start returning to the centerline.

              My $0.02 is that this input is largely appropriate.

              That being said, as the nose arrives at the centerline, the rudder still looks full left...so I concur that:

              1. He/She left it in just a little bit too long.

              and

              2. Yeah, ideally (and based on my position in a chair in front of a computer) he/she should have eased up (or maybe even neutralized) the thing as he/she approached the centerline.

              I continue to struggle with the fact that I feel some left and right oscillations on most airliner takeoffs (as well as remembering doing them myself) [and factor in the telephoto effect] Technically, it's PIO/sort-of-coupling...and no different than driving a car...but a very normal level of "oscillation" that does not amplify...and not meaning to dismiss the swerving as much as saying, it might not be as bad as it looked.
              Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

              Comment


              • #37
                Originally posted by 3WE View Post
                1. Sorry man... black and white mentality... voodoo doll.
                Now open your mind. Take a look at this one (or any of the hundreds of others). Notice the use of rudder. Notice the use of bank. You see rudder INPUT (not occillation) in one direction, then neutral rudder, then a modest amount in the opposite direction needed to decrab ALONG WITH BANK, DOWN LOW and a touchdown IN A BANK in what is obviously a very significant crosswind. There are no reversals involved. And it all ends with the aircraft stable on the centerline, not zigzagging down the runway. Watch as many of thee as you want, watch the rudder and watch the bank angle.

                An Extreme Crosswind Aircraft Crazy Crab Landing at the now closed Hong Kong Kai Tak Aiport as a Korean Air 747 Jet Lands. More information is available in t...

                Comment


                • #38
                  Originally posted by Evan View Post
                  Just til I head the scrapy sound.

                  Com'on Gabriel, you've never seen bank used in a crosswing landing?
                  I am amazed at how often 'the slight bank' goes 'the wrong direction'.

                  I have asked myself: "What are these stupid pilots being taught."

                  BUT

                  After further thought, I have reached a differing conclusion: You really have very limited bank freedom in a low-wing airliner...these 'stupid pilots' are aiming for 'as level as they reasonably can' and when the bank the wrong direction...it's a momentary imperfection caused by wind gusts, dihedral effect from crab adjustment, any number of things.

                  I genuinely doubt that they intentionally bank away from the wind.
                  Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                  Comment


                  • #39
                    Originally posted by Evan View Post
                    Now open your mind. Take a look at this one (or any of the hundreds of others). Notice the use of rudder. Notice the use of bank. You see rudder INPUT (not occillation) in one direction, then neutral rudder, then a modest amount in the opposite direction needed to decrab ALONG WITH BANK, DOWN LOW and a touchdown IN A BANK in what is obviously a very significant crosswind. There are no reversals involved. And it all ends with the aircraft stable on the centerline, not zigzagging down the runway. Watch as many of thee as you want, watch the rudder and watch the bank angle.

                    https://www.youtube.com/watch?v=nehZ9v4YB6o
                    Do you realize how close that was from an engine strike?

                    --- 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


                    • #40
                      BBobby, just out of curiosity, how well (if at all) would the autoland manage a situation like the one faced by this A380? (you can limit your answer to a 747-400 and 747-8 autoland if you want)

                      --- 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


                      • #41
                        Originally posted by Gabriel View Post
                        BBobby, just out of curiosity, how well (if at all) would the autoland manage a situation like the one faced by this A380? (you can limit your answer to a 747-4 and 747-800 autoland if you want)
                        Interesting that you ask this question...You know I'm not a details person, but I thought autoland was a written procedural no-no when the wind became 'significant' and that it is designed more for super-fine adjustments while you land in a reasonably calm fog bank.

                        Is this a trick question?
                        Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                        Comment


                        • #42
                          Originally posted by Gabriel View Post
                          Do you realize how close that was from an engine strike?
                          AND- Evan's video is NOT a gusty crosswind landing as much as an 'unstabilized-not-so-slick' turn to final at Kai Tek.

                          The guy is not fighting the wind per se, as much as he is forcing a huge airplane to get lined up from a very cramped 'base-to-final' turn that he didn't set up as well as he should have...the lack of a gusty cross wind means that we do have steady rudder inputs in this video.

                          As is clear from all of these discussions- there are a wide variety of landings (and an endless variety of wind gusts) and a variety of suggested crosswind techniques...Review additional YouTubes...you will see rudder reversals on some...it's not rare, it's not the end of the world, it's not bad training.

                          Someone also made a very interesting comment...that they weren't overly concerned with a perfectly-straight touchdown...That comment is insightful in numerous ways- not the least of which is that (ironingly) we see plenty of sideways touchdowns that come from over-correction (See Footnote).

                          Footnote: We also see plenty of touchdowns that come from a very pure crab into the wind with virtually no 'kick-out' nor 'wing dip'...and I do believe that is an FCOM-blessed procedure as well as being better than many of the over-corrected touchdowns.
                          Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                          Comment


                          • #43
                            Originally posted by Evan View Post
                            ***Watch as many of thee as you want, watch the rudder and watch the bank angle.***
                            I have.

                            As I state above- Pilot inputs vary- but rudder reversals are not rare, not the end of the world, not bad technique and not bad training...[Your black and white thinking blinds you to the ones where rudder reversals occur].

                            Also see above- please look at gusty CROSSWIND videos and not botched-last-minute-alignment-at-Kai-Tek videos...While SOME of the techniques may be related, the 'gusty' part requires a different pace of control inputs. [Your black and white thinking blinds you from distinguishing stabilized left and right track adjustments from crosswind gusts- these evolve into a gray area.]

                            ...Actually after the A-380 dudes over corrected to the left, I don't fault them for going "oh-crap-right". That was probably a reasonable move for the tires, landing lights, paperwork department, PR department AND their careers. [Your black and white thinking blinds you from seeing why it might be reasonable to switch to right rudder (at~140 knots) when you are making a beeline for the left edge of the runway...no...one must never ever switch from right to left, without pausing at neutral].
                            Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                            Comment


                            • #44
                              Originally posted by Evan View Post
                              The thing is, I'm not a pilot and I never pretended to be one so I'm not going to get into an argument over the AMOUNT of control input that is needed. I am concerned here with the NATURE of the control input.
                              Not sure I follow your logic, namely why not being a pilot enables you to only argue about one of the above. I would think it would be both or neither.

                              Comment


                              • #45
                                Originally posted by ATLcrew View Post
                                Not sure I follow your logic, namely why not being a pilot enables you to only argue about one of the above. I would think it would be both or neither.
                                The actual AMOUNT of control input needed is of course what you learn by doing, by flying in specific situations on specific types. However, the PHILOSOPHY of how you should use control surfaces can be determined by people without without even a single hour of flight time, people known as engineers and incident investigators, through research alone. I read what they publish, all those manuals, reports and periodicals, and I try to learn from that knowledge. But when it comes time to decrab an A380 in a gusting crosswind, I can't tell you specifically how much bank that requires or how much rudder. What I can tell you is that it should never involve large rudder reversals on an aircraft like this because that is going to get you into an overcontrol PIO situation really fast. I also know that a pilot with a tendency towards unnecessarily aggressive rudder inputs on large transport aircraft (which might not be the case here) is a potential threat to the aircraft and everyone on it. As I said at the beginning, this may simply be a case of aircraft-pilot coupling and may not be indicative of poor airmanship. I just hope that, when they get the bill for the tires and the gear inspection/overhaul they will be inspired to find out.

                                Comment

                                Working...
                                X