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Cause of AF1441 touch-and-go at CDG on Nov 27th, 2018?

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  • #31
    Talk about not seeing objects on the runway!!!!

    A Van Air Europe Let L-410 on behalf of Trade Air, registration OK-LAZ performing flight C3-821 from Split to Dubrovnik (Croatia) with 7 passengers and 3 crew, landed on Dubrovnik's runway 12 at about 12:45L (11:45Z) but touched down before the displaced threshold of the runway. The aircraft rolled out safely and became stuck amidst machinery and workers performing runway reconstruction work. There were no injuries, the aircraft did not sustain any damage.

    About 10 minutes later a taxi path was cleared for the aircraft and the aircraft was able to taxi to the apron.

    Croatia's Civil Aviation Authority have opened an investigation.

    Trade Air confirmed their flight C3-821 landed on the closed portion of Dubrovnik's runway, Croatia's CAA is investigating. Fire brigades and ambulances responded and deployed to the aircraft, however, did not need to intervene. A short time later the aircraft was able to taxi to the apron, where the passengers disembarked normally. The aircraft had been leased in from Van Air Europe.

    Dubrovnik Airport is currently undergoing a major reconstruction project, the threshold of runway 12 was displaced by 1745 meters leaving 1425 meters of runway (TORA=TDA=ASDA=LDA=1425 meters) available.


    http://avherald.com/h?article=4c10c0e3&opt=0

    --- 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 ---

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    • #32
      Originally posted by Gabriel View Post
      Talk about not seeing objects on the runway!!!!
      1200Z CAVOK WTF?

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      • #33
        Originally posted by Evan View Post
        One other thought; was it a hard touchdown that might have bounced?
        Nope, felt more like a soft touch ... and then up again.

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        • #34
          However, soft touches can be very related to bounce.

          Contrary to common belief, bounce is not the result of hard landings in themselves.
          Shock absorbers are critically damped so the upper motion after compressing will not reach a speed that will launch the airplane back up into the air. In the same way than a ball of playdough will not bounce any higher if you throw it hard on the floor than if you gently drop it from 1/2 inch. Will not bounce in any case.

          What is the main reason for bounce is pilot action to try to AVOID a hard landing (whether successfully or not is another question).

          So you are approaching and coming down fast (maybe flaring too late, maybe the vertical speed was too much to begin with, maybe there was some slowing on the headwind or some descending air mass, whatever) you what do you do? Of course, you pull up. Pulling up of course increases the AoA which increases lift (in normal situations anyway) and if the lift is bigger than the weight then there is a vertical acceleration (load factor greater than 1) and the sink rate will diminish, which is what you were trying to achieve. But then you touch down, the vertical speed goes to zero, and the lift is still greater than the wight. What happens? Well, you are still accelerating up so up we go. Bounce. The touchdown may be hard, firm, normal or a greaser, it doesn't matter. It even can be inexistent (that "touchless" bounce is called ballooning). If the vertical speed gets to zero for whatever reason and lift>weight, up we go.

          There is a myth that the perfect landing, the perfect greaser, is that where you reduce the sink rate until it becomes zero and you end up touching down exactly at that point (as if you were describing the bottom of a circular trajectory and you touch down exactly in the bottom point where the trajectory becomes tangent to the runway). There is even e name for that: tangent landing. And it's false, it needs to become a bounce (even if a slight one). What you want to do for the perfect greaser is, at least briefly before touchdown, establish a 1G, constant vertical speed trajectory (so lift = weight), with that constant vertical speed being as small as possible but not zero (or you will not touch down, duh!). And finaly, where a perfect greaser is a perfect landing is also a different question. There is consensus that "positive" landings are better and safer for a number of reasons that go from destruction of landing gears due to shimmy to remaining runway available to stop the plane. But the grease feels oh so nice and I don't know a pilot that will not silently say "yes!" after one.

          --- 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 ---

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          • #35
            Originally posted by Gabriel View Post
            So you are approaching and coming down fast (maybe flaring too late, maybe the vertical speed was too much to begin with, maybe there was some slowing on the headwind or some descending air mass, whatever) you what do you do? Of course, you pull up.
            Well, I see what you're saying, but a hard touchdown often leads to 'bounce' and go-around. Before slamming down too hard, the pilot instinct is often to pull up, thus the bounce (for the reasons you describe) and the go-around . So, while I understand the impact itself does not cause the 'bounce', there is definitely an association between hard touchdowns, 'bounces' and go-arounds.

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            • #36
              Originally posted by Evan View Post
              Well, I see what you're saying, but a hard touchdown often leads to 'bounce' and go-around. Before slamming down too hard, the pilot instinct is often to pull up, thus the bounce (for the reasons you describe) and the go-around . So, while I understand the impact itself does not cause the 'bounce', there is definitely an association between hard touchdowns, 'bounces' and go-arounds.
              But the thing is that sometimes the attempt to arrest the hard touchdown is successful and results in a very nice and gentle touchdown, still followed by a bounce due to lift > weight used to arrest the sink rate.

              So the scenario could still be a bounce after touchdown which resulted in a go around even if the landing was not hard.

              --- 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 ---

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