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  • #31
    Originally posted by Evan View Post
    ................................
    As I said, absolute envelope limits on an aircraft like this can be established in the wind tunnel. There's no need to risk lives nor aircraft to verify this. Finding the limits of controlled fiight without exceeding them is another story. From the incident description, my best parlour-guess is that this was a steady sideslip test to determine the following:
    Not all envelope limits can be established in a wind tunnel. I have worked on several aircraft post wind tunnel and all have required flight test to confirm analytical and wind tunnel predictions and also determine an adequate safety margin. My area is designing escape systems and spin/stall parachute systems. One aircraft required extensive flight testing to develop its ventral fin configuration.

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    • #32
      Originally posted by Evan View Post
      Interesting, but this goes against the aerodynamic behavior of rudder control systems that are prone to reversal. As I said back there, the C-130 has a relatively primitive reversible control system (designed in the early 50's!). Most modern transport aircraft have fully powered irreversible rudder controls. Perhaps this FAR was written after the C-130 was designed. And perhaps we need to use bold type on part that says "appropriate for the airplane". Sideslip angles where reversal can occur are prohibited in the C-130 flight manual.
      These rules apply also for crankbell-cable-pulley systems. It doesn't great more reversible or "floaty" than that.

      And there are rules that apply to "angle of sideslip that is appropriate for the type of airplane", but there are others that apply to "larger angles of sideslip up to that at which full rudder is used".

      And since the C-130 in civilian operation would be part 25, not part 23, let's better focus in part 25, especially in 25.177 (d) (2):
      At larger slip angles, up to the angle at which the full rudder or aileron control is used or a control force limit contained in § 23.143 is reached, the aileron and rudder control movements and forces may not reverse as the angle of sideslip is increased.

      --- 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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      • #33
        Originally posted by Gabriel View Post
        These rules apply also for crankbell-cable-pulley systems. It doesn't great more reversible or "floaty" than that.

        And there are rules that apply to "angle of sideslip that is appropriate for the type of airplane", but there are others that apply to "larger angles of sideslip up to that at which full rudder is used".

        And since the C-130 in civilian operation would be part 25, not part 23, let's better focus in part 25, especially in 25.177 (d) (2):
        At larger slip angles, up to the angle at which the full rudder or aileron control is used or a control force limit contained in § 23.143 is reached, the aileron and rudder control movements and forces may not reverse as the angle of sideslip is increased.
        Remember, we are talking specifically about the C-130. Two things to consider:

        1) The C-130 was certified in the 1950's under Part 4b of the US Civil Air Regulations. The FAR's didn't come into force until 1965. What does CAR 4b say about rudder float / rudder force reversal?

        2) The C-130 was designed for short-field performance with gobs of power and thus needed a very large rudder to overcome asymmetrical engine forces at low speeds. The aerodynamic loads that are floating the rudder are considerably larger than any GA aircraft. Is the power / rudder dimension a key factor in how it reaches the point of force reversal (remember, it has never been reached in a power-off situation on the C-130)?

        And remember also, the point I am making is that any test pilot on the AC-130 must be acutely aware of the particular behaviors of the aircraft in unusual attitudes, and this is a prime example of that.

        Comment


        • #34
          Originally posted by Gabriel View Post
          Short version: Rudder force reversal in not acceptable. (the little point is a period)
          ...I'm still not sure that this is quite as bad as the regulations you cite.

          So the rudder kind of goes neutral and or sticks a bit in a hard-over...I guess I don't like that, but I'm totally ass-hat-parlour speculating that the plane doesn't go into a uncontrollable corkscrew snap-roll when it happens...

          ...extrapolating from what Evan (the expert in Airbus FBW AND the 'ancient' C-130) says, when you are done doing your side-slip and dutch roll maneuvers for your PP MEL check ride, you just neutralize the rudder.

          Yeah, sure, it's nicer to just "let off the pressure", but no big deal.
          Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

          Comment


          • #35
            Originally posted by 3WE View Post
            ...I'm still not sure that this is quite as bad as the regulations you cite.

            So the rudder kind of goes neutral and or sticks a bit in a hard-over...I guess I don't like that, but I'm totally ass-hat-parlour speculating that the plane doesn't go into a uncontrollable corkscrew snap-roll when it happens...
            Basically what happens is that as you increase the yaw angle, the float increases and so does the yaw rate, and a competent test pilot can definitely feel that float and should start moderating pedal force. As the yaw angle approaches 'rudder lock', the pilot will also feel a distinct, very obvious buffet on the vertical stabilizer (this is not 'fin stall' however). At the moment of 'rudder lock' the test pilot must start adding opposite pedal pressure to compensate for and arrest the yaw before it becomes critical, which will happen very soon thereafter because if he doesn't arrest it, the yaw rate becomes quite large and a nose-up pitching tendency will become pronounced at around 40°-45° of sideslip, elevating the AoA, and you know what happens next to a particular wing. And, yes, it happens very quickly then that you are looking at the ground spinning beneath you or even above you.

            So, indeed a big deal and one that a test pilot not accustomed to the AC-130 or extreme sideslip with large, powerful reversible rudder control aircraft might not quite grasp in a moment of confused situational awareness. Especially if that pilot thinks that his "universal stick and rudder skills" learned in a 172 apply to this manuever.

            Type-specific procedure 3WE, is a big deal.

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            • #36
              Originally posted by Evan View Post
              Type-specific procedure 3WE, is a big deal.
              Never said it wasn't. Cessna 172A,B,C,D...S...Big differences in carb heat, flap operation, starting procedure, and how to go around at gross weight.

              What I said that you have a very strong disdain for broad, underlying fundamental principles, like exercising caution at extreme attitudes and pulling up carefully as opposed to relentlessly.
              Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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              • #37
                Originally posted by 3WE View Post
                What I said that you have a very strong disdain for broad, underlying fundamental principles, like exercising caution at extreme attitudes and pulling up carefully as opposed to relentlessly.
                What?!!

                Comment


                • #38
                  "What?!!"

                  When you saw a pilot crash a 737-236A, in a 60 kt windshear, you felt that it was because he was more familiar with the FMS of a -200, wheras most of us felt that he failed to firewall the throttles, watch the instruments and go around (using well honed stick and rudder skills to critically deal with the wind shear and attitudes and airspeed as you might do in almost all aircraft.)

                  That's one of many examples. Air France and pitch + power = performance is another.
                  Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                  Comment


                  • #39
                    Originally posted by 3WE View Post
                    "What?!!"

                    When you saw a pilot crash a 737-236A, in a 60 kt windshear, you felt that it was because he was more familiar with the FMS of a -200, wheras most of us felt that he failed to firewall the throttles, watch the instruments and go around (using well honed stick and rudder skills to critically deal with the wind shear and attitudes and airspeed as you might do in almost all aircraft.)
                    I have NEVER expressed a "strong disdain for broad, underlying fundamental principles". That would be insane.

                    In that 737-2ADV incident, the pilot had no training or experience with a modern digital autopilot (major difference between the -200 and the -200adv) and reacted by trying to use it anyway, not understanding the limits of its capabilities. That is an example of an absence of on-type training INTERFERING with core flying skills. Training on procedure would have prevented that.

                    AIr France was a HARD LESSON in the need for procedural training, as the pilots, bereft of procedural proficiency (especially CRM) were left to IMPROVISE while their SA was knocked sideways by the cascade of failures and ramifications of the flight control system degradations. This INTERFERED with their core flying skills. Procedure, designed to split tasks and keep the PF CONCENTRATED on core flying skills while the PNF prioritizes actions vis ECAM and guides him on type-specific system failure actions, would have prevented that.

                    Air France PROVED to us, those of us who were paying attention, that if procedure is skipped over and only core skills are used, SOONER OR LATER, with the right pilots thrown into the right situation, this method will fail. Core skills will fail. As they did. This is called LATENT DANGER due to HUMAN FACTORS, and it is a very common cause of plane crashes. The only defense is CRM and procedural training.

                    Again, for the one millionth time, procedure is there to preserve situational awareness in complex situations on complex aircraft... in EVERY instance, not just the ones where ITS is the pilot and he has had a good night's sleep. With SA preserved and any particular type-specific actions taken, core flying skills will rarely fail you.

                    There ARE numerous situations where a certain aircraft will have certain requirements that are not common to other aircraft. The use of rudder, for example. The use of autopilot. The use of pitch trim. We've been over a lot of these very SALIENT examples.

                    Can't you understand how a pilot with most hours on an irreversible powered rudder, never having done a steady sideslip test manuever on a C-130, could get into real trouble here by not understanding the phenomena of rudder force reversal and relying only on his core flying skills? Cuz its pretty damned obvious to me. If you still don't get the point 3WE, you just never will.

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                    • #40
                      Originally posted by Evan View Post
                      AIr France was a HARD LESSON in the need for procedural training, as the pilots, bereft of procedural proficiency (especially CRM) were left to IMPROVISE while their SA was knocked sideways by the cascade of failures and ramifications of the flight control system degradations. This INTERFERED with their core flying skills. Procedure, designed to split tasks and keep the PF CONCENTRATED on core flying skills while the PNF prioritizes actions vis ECAM and guides him on type-specific system failure actions, would have prevented that.

                      Air France PROVED to us, those of us who were paying attention, that if procedure is skipped over and only core skills are used, SOONER OR LATER, with the right pilots thrown into the right situation, this method will fail. Core skills will fail. As they did. This is called LATENT DANGER due to HUMAN FACTORS, and it is a very common cause of plane crashes. The only defense is CRM and procedural training.
                      Actually, AF447 proved to me (and I was paying a lot of attention) that with poor core skills, procedure won't save you. Reason being, as you yourself pointed out, you will end up misapplying the procedure, even if you know it well. This is exactly what happened. Core skills did fail, yes, but they failed because they weren't used. Task-splitting is not type specific. Any multi-crew flight deck is designed for people to share the load.

                      There is a psychological element to this, too. It seems to me that the statement that is supposed to get the task sharing started doesn't always get proper appreciation or recognition. On Airbus products that statement is (by the PF) "I HAVE THE AIRCRAFT AND THE RADIOS, ECAM ACTIONS, PLEASE" (other types have something similar). This statement must be made slowly, clearly, and loudly. This accomplishes several things. Firstly, it forces the PM to pit down his USAToday (or L'Humanite or Le Figaro in this case). Secondly, it establishes ground rules. The PF is basically saying "I'm busy with the airplane, you see all those messages? They're YOUR problem. Don't bother me unless you have to (like with items that need cross-cockpit verification" Thirdly, it establishes that the PF and PM have basically parted ways. The PF at that point has one job and one job only, and that is to keep the dumb thing right side up (talk to ATC, time permitting). EVERYTHING ELSE is on the PM. They will stay on these separate ways until the PM states "ECAM ACTIONS COMPLETE" (also slowly, clearly, and loudly). That statement basically means "I'm back with you, we're together again". Again, none of this is type-specific, this is just good airmanship.

                      My point is that had the PF focused on his "core skills" and just flown the airplane and had the PM deal with all those "cascading failures", they'd all be alive today. Core skills were poor, hence the procedure got all dorked up as well.

                      Comment


                      • #41
                        Originally posted by ATLcrew View Post
                        Actually, AF447 proved to me (and I was paying a lot of attention) that with poor core skills, procedure won't save you. Reason being, as you yourself pointed out, you will end up misapplying the procedure, even if you know it well. This is exactly what happened. Core skills did fail, yes, but they failed because they weren't used. Task-splitting is not type specific. Any multi-crew flight deck is designed for people to share the load.

                        There is a psychological element to this, too. It seems to me that the statement that is supposed to get the task sharing started doesn't always get proper appreciation or recognition. On Airbus products that statement is (by the PF) "I HAVE THE AIRCRAFT AND THE RADIOS, ECAM ACTIONS, PLEASE" (other types have something similar). This statement must be made slowly, clearly, and loudly. This accomplishes several things. Firstly, it forces the PM to pit down his USAToday (or L'Humanite or Le Figaro in this case). Secondly, it establishes ground rules. The PF is basically saying "I'm busy with the airplane, you see all those messages? They're YOUR problem. Don't bother me unless you have to (like with items that need cross-cockpit verification" Thirdly, it establishes that the PF and PM have basically parted ways. The PF at that point has one job and one job only, and that is to keep the dumb thing right side up (talk to ATC, time permitting). EVERYTHING ELSE is on the PM. They will stay on these separate ways until the PM states "ECAM ACTIONS COMPLETE" (also slowly, clearly, and loudly). That statement basically means "I'm back with you, we're together again". Again, none of this is type-specific, this is just good airmanship.

                        My point is that had the PF focused on his "core skills" and just flown the airplane and had the PM deal with all those "cascading failures", they'd all be alive today. Core skills were poor, hence the procedure got all dorked up as well.
                        I agree with everything you said except for this:

                        Actually, AF447 proved to me (and I was paying a lot of attention) that with poor core skills, procedure won't save you. Reason being, as you yourself pointed out, you will end up misapplying the procedure, even if you know it well. This is exactly what happened.
                        I disagree with this because everything else you've pointed out IS PROCEDURE, that is, CRM procedure is task division, order under chaos and the opposite of IMPROVISATION. The memory items are quite simple: 5° pitch / CLB power (move levers to defeat thrust lock). It does not require much core skill. Once this is accomplished, everything that follows, ECAM actions, QRH, etc, is done is stabilized flight. In most cases by the time these lists are run, the event is over anyway. What I believe happened was severe mental confusion and distraction from basic flight skills due to a lack of CRM training and proficiency (that is procedure) by a crew completely unaccustomed to concentrating on flying the plane at altitude. In other words, it was a concentration issue, not a skills issue.

                        This is why I especially agree with this:

                        Again, none of this is type-specific, this is just good airmanship.
                        Procedural discipline and proficiency is a part of good airmanship.

                        Beyond that there WERE type-specific factors that contributed to the chain of events.

                        Comment


                        • #42
                          Guys, you are so naive.

                          A pilot that, upon the onset of the issue, immediately freezes and completely stops thinking or reacting rationally will not do the simple 5 dec / CLB, will not call "I have the plane and the radios, you have the ECAM", and will not use his skills to keep the blue side up.

                          The pilot pulled up strong enough that he triggered the stall warning a second after the AP disconnected, established a 1.5G, 15 deg nose-up, 7000 fpm climb and when the plane finally stalled, he pulled up again and kept "pulling up all the time". Not following the UAS procedure and lack of CRM cannot explain this (except in the trivial and useless way that, yes, they didn't follow the procedure or the CRM). The pilot was out of the game since t=0.

                          It's like if, in a IMC approach, at 500ft the AP disengages and the pilot reacts immediately yanking the yoke all the way to the left and rolling inverted, and you blame CRM and not following the missed-approach procedure.
                          It's not so simplsssimplsimplsssimmmplsssimplsssllsipmsssisplsssmisslle (<=== sorry, I mispelled "simple", or would you call that a spelling error?)

                          --- 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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                          • #43
                            Originally posted by Gabriel View Post
                            Guys, you are so naive.

                            I read these posts and just have to laugh!

                            I am sure it was the center wing fuel tank that was the problem.

                            Comment


                            • #44
                              Originally posted by Gabriel View Post
                              A pilot that, upon the onset of the issue, immediately freezes and completely stops thinking or reacting rationally...
                              Come'on Gabriel, who's being naive here? Do you really think it's as simple as that?

                              First of all, unfortunately he didn't freeze, he acted, wrongly. "Why?" is the million-dollar question, we agree on that.

                              I don't think he "stopped thinking". I think he had his hand on the stick and his eyes—and full attention—on everything but the primary instruments. As I posted a good while ago on the AF447 thread (where this discussion belongs), there are comments on the CVR just prior to the event that indicate his attention and concern were on the engines, not the flight path, and his eyes were probably volleying between the ECAM and the SD at that point whereas the PFD probably wasn't getting any attention.This is textbook breakdown of CRM, where both pilots are playing the role of PNF. He might have also wanted to climb at a safe attitude to get above the weather but was adding more pitch command than he realized (try doing this without looking at the PFD).

                              So what about the repeated stall warnings? I think he considered them false due to the loss of airspeeds and plethora of other system failures. If he perceived that he was only in a moderate climb at full climb power, and he didn't understand how the stall warning system works—because he didn't know his aircraft very well—that makes perfect sense.

                              Of course he was in a dangerous climb attitude, his thrust was locked down around 70% N1 and the stall warnings in alternate law are driven by the AoA vanes, independent of the airspeed sensors, and are therefore valid (hence the procedure clearly states: RESPECT STALL WARNINGS). I don't think he was aware of any of this.

                              When things that you think should behave in a certain manner start behaving in a very different one, for whatever reason, the mind loses situational awareness and starts rationalizing its own reality. At that point, the actual reality becomes increasingly remote to the rational mind.

                              If CRM had prevailed, his hand would have been on the stick and his eyes would have been mainly on the PFD. His task, instilled in memory and also called out by the PNF, is incredibly simple; it does not require great skill. It does require a steady hand, a cool head and undivided concentration. That is exactly what CRM is there for. That is why we have written procedures. To prevent a situation where improvisation goes wrong. And that is why it should be well-practiced in the SIM.

                              Yes, with a focused crew, a dozen or more incidents can go by uneventfully with no application of procedure but this is still bound to happen. CRM procedure is the only defence against the one that is bound to happen.

                              Comment


                              • #45
                                I think I'd put it slightly differently, and much more succinctly, as "the pilots panicked".

                                I bet either one of them, in a low-pressure classroom situation, could have recited the proper procedure for handling unreliable airspeed indications, and could have told you that in alternate law the stall warnings are still valid and why. The problem is, this was not a low-pressure classroom situation!

                                Or in other words the failure was not that procedures were not in place, and not that the pilots were not well trained on the appropriate procedure and the aircraft's systems, but that when the s**t hit the fan, their brains did not access and use that information correctly.

                                I'm not necessarily trying to say "people f**k up and there's nothing you can do about it"... while I think sometimes that's the case, other times it's not.

                                But if you've instructed your people 100 times on how to do something and they're still not doing it right, I don't think instructing them 25 more times is likely to help. You need to find a different approach... somehow.
                                Be alert! America needs more lerts.

                                Eric Law

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