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  • #76
    Originally posted by 3WE View Post
    Actually, I am a slow, but hands-on learner but still do not necessarily agree with you.
    Hey, that's good (as long as we keep discussing the subject and not the credentials).

    Shortly after my post, it hit me...the problem is with the 20 knots head start, I can hit 80 in 20 seconds with a possibly real acceleration issue and continue my takeoff or worse my not_takeoff.
    Exactly that IS the issue.

    But then you go on asking how much variation can there be in the "20 sec to 80 kts" rule. How far can we be from about 80 kts after about 20 seconds.
    That is not the useful question here.

    Let's assume that the rule is pretty robust and that, no matter what, you will always be at about 80 knots after about 20 seconds.
    The real question is how robust the take off performance is, given that that condition is met.
    That is, how much variation can there be in the distance run to achieve V1 (compared to the theoretical one taken into account when the take off calculation was done). And the answer there is, a lot.

    So, what is the value of checking that you achieved about 80 kts in 20 seconds if that means not much for whether your take-off performance is doing good or not?
    Remember, we are trying to see if your take-off performance is the expected one, so you need two things: 1- A variable that is strongly correlated to the take-off performance and 2- A reference value to compare that variable against.

    "Time to achieve 80 knots" could be a good variable (if the technique to initiate the take-off is solid consistent (like rolling vs standing, technique to advance the thrust levers and stabilize the engines... etc), which is quite questionable to begin with. But "about 20 seconds" cannot be a universal benchmark. If your take-off performance calculation is based on a headwind of 25 kts and you actually have your 25 kts, you better achieve 80 kts in much less than 20 seconds.

    I would say that every take-off would need it uniquely calculated "time to achieve 80 kts" as much as every take-off needs its uniquely calculated V1, Vr, V2, trim setting, flap setting, and thrust setting. (and that, again, assuming a consistent technique at the beginning of the take-off roll, which is not the case).

    --- 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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    • #77
      Originally posted by ATLcrew View Post
      I guess I'm just not sure about taking personally and wasting precious nerve cells on a subject with which one ultimately has nothing to do. By your own admission, you haven't flown anything in nearly two decades, so this is an entirely academic subject to you. It bears mentioning, too, that, for all you know, neither has BB flown anything in 18 years (or more). In fact, you have no less evidence that he is 15 and living in his Grandma's trailer than you do that he is a widebody Captain. So, getting all wrapped around the axle about him shoving his "credentials" in your face also seems pointless. Nor is it of any great importance which one of you is "right" or "wrong". Nothing either one of you (or anyone else) says on this forum makes any real difference, so perhaps taking 3WE's advice and chilling a little might be a good idea. Especially when, also by your own admission, you have some personal issues to handle.

      Then again, your nerve cells are yours to waste, too...
      Ok, I take that I need to chill down.
      Other than that, what's the purpose of a DISCUSSION forum?

      I would hope that it is to DISCUSS things (in this case, aviation safety), hopefully in a respectful and constructive way, which will hopefully make us all reflect on the things being discussed, and perhaps change our view on some of them, gain some awareness in others and, why not, out right learn some others or unlearn some that we had wrong.

      I cannot say that all this is futile and merely academic. There are pilots in these fora, there are passengers (hey, I can be the guy in 28C on the next plane that runs past the runway end at full speed and full throttle attempting an impossible take-off because the performance calculation was wrong, people already died of that). Not to mention that I plan to return to flight some day. And I know that I've learnt a lot in these forums. From others, but also from myself, from reflecting on subjects with a depth I had not done before, from reading things triggered by these discussions, from researching and analyzing my own arguments to defend my opinions or criticize other's. To mention one significant example, now I understand much better human factors and I am much aware of the "traps" I can fall in, which should help me recoginze them in time to avoid them. Mission accomplishment, tunnel vision, confirmation bias, fatigue, and even discipline. I know I am a better pilot today than when I quit flying 17 years ago. (ok, maybe rusted and out of shape due to lack of practice, but with a better background and understanding).

      And... you also have the entertainment part. Regardless of it's "real" value, I enjoy so much discussing a subject that I am passionate about (even if I may get mad every once and then)

      --- 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


      • #78
        Okay, Although I may not be a "real" 747 Captain according to my esteemed colleague ATLCrew, I am wondering. My FMS generates V1, VR and V2 on my PFD, I set V2 on the MCP which also puts a magenta bug on the PFD. I gaze at the clock when I apply takeoff thrust, and you want another bug on the PFD for the PM or myself to look for? Don't I have enough visual clues already?

        P.S. By the way, anytime any of you are in the Miami area and would like to meet face to face, I will be glad to pick up the tab for lunch.

        Comment


        • #79
          Originally posted by BoeingBobby View Post
          My FMS generates V1, VR and V2 on my PFD, I set V2 on the MCP which also puts a magenta bug on the PFD.
          Sorry to be an irritating bitchy ankle biter...my understanding is that all the stuff you list are speeds, and (this is a math thing) they don't say squat about if you are speeding up on target. For that you need a time component. Without a time component, you can mosey down the runway as long as you want and eventually hit Vr about the time you hit the big-ass numbers.

          Now, I'm the one guy acknowledging that you are keeping busy monitoring all sorts of crap to assure a safe takeoff and doing a damn good job of it (and I now 'fully endorse' your clock thing which does contain speed and time and serves as an acceleration check. And I'm sure you are very happy to have that endorsement from me).

          But to hell with Gabriel, Evan and Me...Evan posted a seemingly official document from a seemingly official safety organization saying that you do need a little more help, so we'll see what the future holds.

          Gabriel (and I guess me too), think it can be done in an unobtrusive, extremely intuitive manner....(And, like before, I'm sure that is very comforting to you)

          The fact that you put up with us and our free advice is appreciated.
          Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

          Comment


          • #80
            Originally posted by BoeingBobby View Post
            Okay, Although I may not be a "real" 747 Captain according to my esteemed colleague ATLCrew, I am wondering. My FMS generates V1, VR and V2 on my PFD, I set V2 on the MCP which also puts a magenta bug on the PFD. I gaze at the clock when I apply takeoff thrust, and you want another bug on the PFD for the PM or myself to look for? Don't I have enough visual clues already?
            Yes, but you would not need to gaze at the clock when you apply take-off thrust and again when you reach 80 knots. The new bug would be mostly static (not moving like the airspeed bugs) because the acceleration remains fairly constant (or, in other words, varies slowly) during the take-off run, it would be right at the ASI bar in the PFD and you would look at it at 80 knots (and plus or minus a few knots would make no harm at all), exactly when you need to look at the ASI bar anyway for the 80 kts crosscheck. Me says it is a quite friendly indication and procedure.

            P.S. By the way, anytime any of you are in the Miami area and would like to meet face to face, I will be glad to pick up the tab for lunch.
            Deal and ditto. Let me know if you ever come to El Paso TX (oops, just realized, this is another bit that I need to update in my profile).

            --- 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


            • #81
              Originally posted by BoeingBobby View Post
              P.S. By the way, anytime any of you are in the Miami area and would like to meet face to face, I will be glad to pick up the tab for lunch.
              does this apply to locals too? hell, with what i've learned reading your posts, i should probably buy you lunch!

              Comment


              • #82
                Soooo...how about I hijack the thread with something that is 50% on-topic, but also 50% off-topic.

                Here's a crash where there was a takeoff performance problem.



                Contributing factors are:
                -Imperfect CRM
                -Cowboy fudging of health and fitness

                I see that the official cause is that the pilot inadvertently applied brakes (and due to nerve problems was unaware of these actions).

                But, for the Russian conspiracy bunch, there was a TV documentary inferring that there was significant, improperly-reported slush accumulation on the runway. (Snow plow driver a relative of someone important? Moved trees?, You just never know).

                Would Gabe's TOPMS system have saved the day here?

                A Bobby 80-knot time check?

                Or was it a very pure CRM breakdown of the crew to not_detect the braking and grossly botch the decision to abort/continue.

                Maybe the braking may have started after V1? My understanding is that the plane de-rotated!
                Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                Comment


                • #83
                  Originally posted by Gabriel View Post
                  Not yet... but you don't need to be Nostradamus to tell that the question is not IF, but WHEN.

                  Are "we" really going to wait until an A-380 with 600 persons on board crashes in downtown Tokyo at rush hour to take action?
                  Isn't the row of incidents that most of the times luckily don't end in tragedy enough to take action NOW before we have a high body toll?

                  The clock is ticking... When it happens, I don't want to hear the word "accident": It will be manslaughter with criminal negligence (and not by the pilots).

                  http://avherald.com/h?article=49e9d96c&opt=0
                  Hm. You don't have this flight in mind, or do you.
                  The only airline who flies the doubledecker airbus into my home airport.

                  If you have this in mind, you are not the only one. High temp, plus variable conditions = a problem for computers.

                  AV herald seems to be a serious source. Or, let me take it serious, since you quote it.
                  'The first officer noticed that the engines stabilized at 1.38 EPR instead of the expected 1.41 EPR, moved the power levers to achieve 1.41 EPR, however, the autothrust system returned the thrust levers to 1.38 EPR about 4 seconds after the first officer's intervention.'

                  Didn't I mention it in the B773ER thread? I neither use a/t nor a/p during t/o. The only thing that I use is fmc to get some sort of recommendation. Doesn't have to be a perfect solution, but as my response time is quicker, I really like to avoid the automatic during take off.

                  Let's just think of a car that is going to use the acceleration lane. Do you use a computer for that? I don't think so. You know how fast you'll have to be to fit into the right lane, ...
                  at least if you don't use the acceleration lane for the first time. But this is the reason why we have driving instructors and flight instructors.

                  Wasn't there a difference between the last driving lesson, where the instructor was able to correct something and gave final hints, and the first time that we were responsible for the acceleration lane?
                  Probably I am old school, but I have learned to use the acceleration lane without a computer.

                  Can we compare that to runways and airports? I have never heard of a Porsche driver who asked for a computer to use the acceleration lane. And why not? Because he knows how fast he has to be.
                  AND it is fun for him to do it manually.
                  The German long haul is alive, 65 years and still kicking.
                  The Gold Member in the 747 club, 50 years since the first LH 747.
                  And constantly advanced, 744 and 748 /w upper and lower EICAS.
                  This is Lohausen International airport speaking, echo delta delta lima.

                  Comment


                  • #84
                    Originally posted by TeeVee View Post
                    does this apply to locals too? hell, with what i've learned reading your posts, i should probably buy you lunch!
                    Is this an invitation?

                    Since the DUS-MIA nonstop connection with LH disappeared, it's not that easy. But I'd almost reversed the invitation. If you, TeeVee, plan a landing on my home airport, I'd like to buy you something.
                    The only condition: I say the name of the bar.
                    Last edited by LH-B744; 2016-10-07, 00:24. Reason: For TeeVee.
                    The German long haul is alive, 65 years and still kicking.
                    The Gold Member in the 747 club, 50 years since the first LH 747.
                    And constantly advanced, 744 and 748 /w upper and lower EICAS.
                    This is Lohausen International airport speaking, echo delta delta lima.

                    Comment


                    • #85
                      Originally posted by LH-B744 View Post
                      Is this an invitation?

                      Since the DUS-MIA nonstop connection with LH disappeared, it's not that easy. But I'd almost reversed the invitation. If you, TeeVee, plan a landing on my home airport, I'd like to buy you something.
                      The only condition: I say the name of the bar.

                      Comment


                      • #86
                        Oh no. Not two at once. Only if seahawk supports me.

                        If here is space for three smileys in a row, there should be space for a very short MIA answer. My focus, with my nickname has changed to MCO. But not this friday. Brandnew information.
                        The German long haul is alive, 65 years and still kicking.
                        The Gold Member in the 747 club, 50 years since the first LH 747.
                        And constantly advanced, 744 and 748 /w upper and lower EICAS.
                        This is Lohausen International airport speaking, echo delta delta lima.

                        Comment


                        • #87
                          Originally posted by 3WE View Post
                          Soooo...how about I hijack the thread with something that is 50% on-topic, but also 50% off-topic.

                          Here's a crash where there was a takeoff performance problem.



                          Contributing factors are:
                          -Imperfect CRM
                          -Cowboy fudging of health and fitness

                          I see that the official cause is that the pilot inadvertently applied brakes (and due to nerve problems was unaware of these actions).

                          But, for the Russian conspiracy bunch, there was a TV documentary inferring that there was significant, improperly-reported slush accumulation on the runway. (Snow plow driver a relative of someone important? Moved trees?, You just never know).

                          Would Gabe's TOPMS system have saved the day here?

                          A Bobby 80-knot time check?

                          Or was it a very pure CRM breakdown of the crew to not_detect the braking and grossly botch the decision to abort/continue.

                          Maybe the braking may have started after V1? My understanding is that the plane de-rotated!
                          The problem was with lock on the the cockpit door. They should never have been given the key.

                          It was later revealed that the pilots had used falsified documents to obtain permission to fly the aircraft, and that they lacked the training necessary to fly the Yak-42. In addition, the co-pilot had undergone treatment for a nerve disease and was forbidden to fly.
                          The captain was panicking after Vr, apparently bracing his feet on the brake pedals while pulling up relentlessly, which means pushing down on the brake pedals relentlessly.

                          But the initial reason for the failure to rotate seems to be a late application of proper take-off power (as this flight was too heavy for the 'nominal' setting they initially used}. A performance issue.

                          TOPMS would have alerted them to the fact that the plane wasn't accelerating at the expected level. That should hopefully result in a low-speed rejection, or at least an early enough application of full thrust, but this being Russia, who knows. They'd probably pull the cb on that thing and sell it at a local bazaar.

                          TOPMS could have prevented the panicked improvisation that seems to cause most accidents these days. Better on-type training could also have prevented it.

                          Comment


                          • #88
                            Originally posted by LH-B744 View Post
                            Is this an invitation?

                            Since the DUS-MIA nonstop connection with LH disappeared, it's not that easy. But I'd almost reversed the invitation. If you, TeeVee, plan a landing on my home airport, I'd like to buy you something.
                            The only condition: I say the name of the bar.
                            Make sure it's not the Blue Oyster Bar !!!
                            If it 'ain't broken........ Don't try to mend it !

                            Comment


                            • #89
                              Originally posted by brianw999 View Post
                              Make sure it's not the Blue Oyster Bar !!!

                              Maybe that explains it!

                              Comment


                              • #90
                                Originally posted by LH-B744 View Post
                                My focus, with my nickname has changed to MCO.
                                You headed to Orlando to play with Mickey and friends? I will alert the media. Hey at the same time you are headed here, I go to Haan on Monday, maybe we can wave at each other.

                                Comment

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