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  • Originally posted by Gabriel View Post

    "expert" is not convincing enough by itself. At least for me.
    Exactly. So, why bother asking? You need more things with which to disagree?

    Comment


    • Originally posted by ATLcrew View Post
      I doubt you'd "love to hear it", Gabriel. Your track record lends itself rather poorly to the idea that an expert opinion of ANY kind is particularly welcome in your world.
      You are wrong, or ill-intentioned.

      --- 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 ATLcrew View Post
        Originally posted by Gabriel
        "expert" is not convincing enough by itself. At least for me.
        Exactly. So, why bother asking? You need more things with which to disagree?
        Because, and I don't know if you read my post, but...

        I have nothing against experts, on the contrary, I love experts and even I myself may be an expert in some very specific and narrow fields of knowledg
        And while

        experts can be occasionally wrong
        the fact is that

        expert will be right over dummies a majority of the times
        Now,

        If you are really an expert, you better have better ways to explain to me why I am wrong and you are right other than displaying your credentials and questioning mine. Otherwise, you are either not an expert or are one that doesn't deserve being respected as such.
        Because, while

        "because I am an expert and I know better" is not a good argument
        and hence

        "expert" is not convincing enough by itself, at least for me
        an expert should be able to express his

        expert opinion on the subjects being discussed, exposed not just as statements of absolute truth but with arguments explaining why he thinks what he thinks
        and do it brilliantly and nail it.

        Because, in my opinion, and according to my values and my ethics model, one should

        --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
        --- Defend what one says with arguments, not by imposing one's credentials ---
        And if you find or ever found a case where I did not follow this ethics model, please call it out. I make mistakes too and I might owe an apology to someone.

        --- 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
          The stall warning at the top of the climb happened at about M 0.66 and it is difficult to tell exactly where the actual stall happened but they were somewhere between M 0.60 and M 0.62.
          I conclude that the pronounced pitch-up was more due to the pronounced nose-up sidestick inputs than the effect of stall at high Mach numbers.
          Of course. I just wonder if this chain of events was made of a lot of little things, lets call them 'links'. But maybe the mach/wingtip/pitch effect isn't significant at those lower numbers.

          BB mentioned time ago how he would usually hand-fly the plane from take-off to some FL200 (if I remember correctly) to the dismay of his FOs who questioned why he would do such a reckless thing in opposition to the company policy of going AP/AT at 400ft.
          There was a good article written by one of the chief test pilots on the A380 addressing the contradiction that pilots need to be proficient at manual flight at all operating altitudes, but are prohibited from practicing in RVSM airspace. The conclusion was to practice in the sim, but there are two problems with that. One is that the sim cannot accurately represent the g-force sensations of dynamic maneuvers at cruise-level and thus would be negative to training since it would instill a false understanding. The second is that the sims are programmed from data gained through countless test flights, but the test flights can only exceed CI by about 4°, so everything beyond that is impossible to accurately simulate. That means you cannot train for actually stall recovery from high altitude in the sim. So, in terms of manual flight handling practice (not procedural knowledge) how do you resolve that one?

          BoeingBobby is older than RVSM and over those 25,000,000 flight hours probably... maybe... possibly got some stick time in on the 74 or one of the other 7's while cruising above 25,000??? Dynamic maneuvering even??? It would be interesting to get a firsthand report on how different it actually is...

          Comment


          • Originally posted by Evan View Post
            So, in terms of manual flight handling practice (not procedural knowledge) how do you resolve that one?
            There are many ways to tackle that:

            1- You hand fly frequently, at least when not in RVSM.
            2- In RVSM, it is my understanding (and I can be wrong) that you can hand-fly climbs and descents (what's critical is when you have to maintain an altitude with precision, there is where you need the AP). So you can hand-fly all the way from take-off to TOC and from TOD to landing, plus any step-climb or step-descent while at cruise.
            3- You study the procedures for upset recovery, UAS, stall, etc and practice them in the simulator.
            4- You practice dynamic maneuvering at the limit of the flight envelope (including excursions beyond the envelope) in the flight simulator.
            5- You can do 4 in simulators of different types than the one you fly.
            6- You take an advance maneuvering and upset recovery training in a real plane (not your type, of course).

            I know, not perfect, nothing will be an accurate simulation of stalls and other excursions at the limit of the envelope. But:
            - It will be close.
            - While the reaction can be somehow different, the general motion and the actions needed and the reaction to those actions will be similar.
            - The laws of Physics are the same for all airplanes.
            - In the past 3WE and myself mentioned how playing Flight Sim and using different simulated airplanes in different altitudes, speeds and situations was not an accurate representation of any particular aircraft in any given situation, the Physics model is there so you get exposure to how different behaviors, and you get the flexibility and adaptability to fly the next simulated (or real?) type for the 1st time. It's basically what test pilots do. Fundamentals are consistent among types. As an example, reducing the AoA is an appropriate reaction for a stall warning at cruise altitude in a Cessna 172, in Colgan, in AF4467 and in Spanair at Barajas.
            - If you are used to drive a Ford Fiesta and get behind the wheels of a Ford Expedition, you will not find much difficulty in driving it safely and even performing generally correct emergency braking, obstacle evasion and ovesteering recovery, if you mastered that in the Fiesta.

            Again. Perfect? No. Good? Yes.

            --- 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
              That means you cannot train for actually stall recovery from high altitude in the sim.
              Ok...they said that (not you)...but why the hell not?- and I'm going to call a BS! on that (the symbol is an exclamation point)

              Based upon a few zillion posts on this topic, I recall an actual ATP (in a post that I read) once saying that due to the swept wing and all, that the actual development of stall was not particularly "tactile"...that the plane eased into it...(seems consistent with Air France).

              Stall detection depended upon reconciling attitude and declining attitude and two or three other things that I can't remember at this point.

              Stall recovery depends upon reducing AoA (did I get that right Gabe?)...you'd then want to see that airspeed and attitude and AoA (which a lot of airliners have fancy indicators) are all healthy and you carefully manage pitch to promptly (but with common sense restraint) return to your target altitude without re-stalling...Yeah, sure seat of the pants adds to it, but it's actually really procedural and instrumentical. You should really like that. Again, there's two or three other things you 'monitor' but I can't remember right now.

              Oh yeah, I just remembered those other things. Stick shaker, stick pusher and aural stall warnings...Yeah, they are part of it and are very powerful indicators of incipient and actual stalls and your recovery status...all work really well in a sim.

              And...as we think about those indicator thingies- which are kind of spectacular...I wonder if the sim time isn't better spent recovering from an incipient stall, instead of an actual stall...

              Maybe that and a little training time that relentless pull ups can sometimes lead to stalling...

              Yeah, I get the buttocks factor and the late night startle factor, but it's all soooooo mechanical- and I can see very good practice sessions and procedure regurgitation (with oral call outs for CRM) in a sim- you can even turn off the warning systems and make the pilot look for unexplained descents from slow airspeeds...or not.

              One other thing- you said "High altitude"...seems to me that's a really forgivable place for sloppy technique...Oh, no, I blew 2000 feet of altitude...so expletive what- practice it in the sim to hell with seat of the pants inputs.

              Yeah, as an industry, we are probably overly focused on the Departure stall where if we don't minimize altitude loss we hit dirt or tree lines or nearby high mountains with no way to turn away...Having little or no altitude loss, is sign of a well honed "hand on the yoke" and a brain wired to firewall the coal stoker levers and manage AoA just right.

              Of course, this probably varies widely between 172's Q-400s and A-300s so no knowledge can be transferred from one to the other.
              Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

              Comment


              • Originally posted by Gabriel View Post
                n RVSM, it is my understanding (and I can be wrong) that you can hand-fly climbs and descents
                True? False? RVSM was the result of autoflight height-keeping technology. It seems to me that things like overshooting a manual level-off might bust that requirement. From that article:

                For a maneuver at identical load factor, the radius of curvature of an altitude capture is multiplied by four [at higher altitudes] and therefore, starting from a given slope, anticipation for this maneuver must be multiplied by four in order not to exceed the target altitude.
                Originally posted by Gabriel
                - It will be close.
                But is that a good thing or a bad thing? From the article:

                As I have done several thousands of hours of tests of all sorts on simulators before doing them in flight, I can confidently say that the models supplied by the simulators are very close to reality. However, two important limits exist and must be known, which are the very high angles of attack and the representativeness of the cabin movements... Whenever significant dynamic movements are done, the feelings become very false and can clearly have counterproductive training effects as the pilots then perceive sensations contrary to what they would experience in reality... For this reason, during the flight tests, cockpit movements are never used to fine tune the flight controls knowing that the sensations experienced are, essentially false, and can therefore seriously alter test pilots assessment of these.

                Comment


                • Do you have a link to that article?

                  For a maneuver at identical load factor, the radius of curvature of an altitude capture is multiplied by four [at higher altitudes]
                  Ok, if you are going faster (and I mean true airspeed not IAS), a given acceleration perpendicular to the speed vector will cause less curvature (i.e. bigger radius of curvature) given by circular motion cinematic equation a = v^2/r, which translates to r=v^2/a. At a high cruise altitude, same IAS, you can be almost at twice the TAS than at low level. Double the speed - 4 times the radius, do to the speed being squared.

                  and therefore, starting from a given slope, anticipation for this maneuver must be multiplied by four in order not to exceed the target altitude.
                  Define anticipation.

                  First, of all, if the slope is the same and speed is twice as much (so curvature will be 4 times as much), the vertical speed will also be twice as much.

                  To go from a given vertical speed to zero, you have:

                  V=a*t

                  You can clearly see that if V is the vertical speed and it is twice as much, and the acceleration is the same (because the load factor is the same), then the time will also be twice as much.

                  Anticipation in distance?

                  Z = 1/2 * a * t^2 (Z is the altitude you are going to gain or lose in the maneuver)

                  So yes, double slope means double the speed, double the speed means double the time, double the time means 4 times the distance.

                  Now, and here is where it is misleading... Same slope???????? Come on!!!!

                  So you are climbing at low level at 250 knots indicated (250 knots real) and say 3000 fpm, and you will reach 35000 ft at 250 knots indicated (500 knots real) and 6000 fpm??? What are you, Air France???

                  Climb speeds at high altitude are LESS, not more, than at low levels, because the engines produce quite less thrust. A descent requiring leveling off at a lower altitude? Ok, you can descend from FL350 at 3000 fpm, but 6000? I don't think so. And the pilot doesn't even know or care about the slope (mostly). Climbs and descent are managed with vertical speed, not slope (mostly). Or show me the "hold slope" knob in the AP.

                  Using "same slope" is misleading. It's not what happens. Worst case you have "same vertical speed".

                  What it takes to level off a 250 kts IAS 3000 fpm climb at low level vs cruise altitude using identical load factors?

                  And know what?
                  Put same vertical speed and same acceleration in the above equations.
                  You get same time and same vertical distance to level off.
                  AND THE RADIUS OF CURVATURE IS STILL 4 TIMES LARGER.

                  Whenever significant dynamic movements are done, the feelings become very false and can clearly have counterproductive training effects as the pilots then perceive sensations contrary to what they would experience in reality... For this reason, during the flight tests, cockpit movements are never used to fine tune the flight controls knowing that the sensations experienced are, essentially false, and can therefore seriously alter test pilots assessment of these.
                  I am not sure I understand this. But what of this doesn't apply to, I don't know, steep turns at low level?

                  --- 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
                    Now, and here is where it is misleading... Same slope???????? Come on!!!!
                    I'm just tellin ya what the man in the orange jumpsuit said...

                    https://www.airbus.com/content/dam/c...agazine_20.pdf

                    Page 37 I think.

                    Comment

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