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  • #16
    Originally posted by Evan View Post
    MEMORIZED pitch and power settings. Not IMPROVISED pitch and power settings.
    I don't know if I'd use the word "improvised" for pitch and power settings that the pilot used the 1000 last times.

    --- 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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    • #17
      Originally posted by Evan View Post
      The AF447 pilots WERE NOT TRAINED to do anything, that was and still is the problem. Hopefully this is not true of JetStar.



      MEMORIZED pitch and power settings. Not IMPROVISED pitch and power settings. That is to stabilize. Again, if this crew did that first and then descended using pitch and power settings established by airbus engineers, then I am not nearly as concerned. But I still question of the wisdom of the descent (question, as in, I would llike to know more details about the incident, which hopefully will be released some day soon).

      On the other hand, if they simply reacted by descending without first stabilizing and consulting the QRH (or having the safe pitch setting memorized), I am very concerned.
      I distinctly remember ONE person (maybe more than one) stating CONFIDENTLY if the pilots of AF447 has simply done aviating, there was no reason for the plane to fall. That the automation somehow distracted them from the most fundamental things pilots are taught. Paraphrasing, looking for FANCY solutions and ignoring the simplest ones doomed them. This makes me wish I created a quote library for the eventuality when other crashes make them useful. Then I wouldn't be leaning on memory that doesn't make me so confident. Anybody agree with the idea that there is BASIC aviating that should be a floor when the technology goes wacky? I wonder what Sullenberger fell back on to land his plane.

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      • #18
        Originally posted by Gabriel View Post
        I don't know if I'd use the word "improvised" for pitch and power settings that the pilot used the 1000 last times.
        At what weight? For a target speed of .78M, the QRH calls for a range from -0,5° to -2.5° for descent. Not 0* BTW.

        And are you saying that a descent is safely in the envelope at 0° pitch and idle thrust? Then why should they bother to monitor airspeed the other 1000 times?

        Is it really necessary to monitor airspeed in this attitude/thrust configuration? And if so, why?

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        • #19
          Originally posted by Gabriel View Post
          I don't know if I'd use the word "improvised" for pitch and power settings that the pilot used the 1000 last times.
          No, "we" would not use the word "improvised." Your comment catches the essence well.

          However, what you are missing is that it would require the pilot to think as opposed to mindlessly regurgitating some cryptic, acronym-laden procedure that makes fundamental airmanship (like what Economy refers to) seem like a foreign concept.

          And given that so many pilots are idiot cowboys, "we" don't want that.
          Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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          • #20
            Originally posted by Evan View Post
            ...Then why should they bother to monitor airspeed the other 1000 times?

            Is it really necessary to monitor airspeed in this attitude/thrust configuration? And if so, why?...
            You cannot (nor have you ever been able to) comprehend "why" as your strong tendency to think black and white prevents you from dealing with gray areas and good airmanship and that the "six intstruments" must 'always' be actively monitored and that you be prepared to diagnose which ones are right, which ones are wrong, and then take a course of action to address it.

            Selecting a fat, dumb and happy descent power and attitude works (whether you look it up in the engineer blessed book, or recall your last 1000 descents (some of which were probably heavy and some of which were probably light...God forbid the pilot have a real good idea of what that attitude and power setting is).

            Yeah, it's all important and yeah, the loss of airspeed indication is significant.

            If you don't "always" monitor airspeed, you wind up slowly decaying it and smacking the sea wall instead of the fixed distance markers.

            If you don't "always" monitor airspeed, you wind up stalling your Q-400 after leveling, adding gear and flaps, flattening the props at 2000 ft AGL and wind up in a sudden, unexpected stall after you've been awake 20 hours.

            If you don't "always" monitor airspeed, you may wind up going the wrong speed for ATC.

            Yeah, you should "always" monitor airspeed, and if your ASI (whatever it is) quits...you should, in fact, promptly do something!

            A professional pilot is telling you that a carefully-executed descent to where the buffet margins are wider is a good option of something to do...but please, just sit there and argue against him AND your favorite ass-hat outsiders.

            If the ASI isn't working, I'm thinking you increase our SA for any (of many) backup indications that your airspeed is out of whack...too little air noise and control mushiness (oh crap, it's an airbus, never mind)....to much noise and some funny behavior...AOA Stick shaker...maybe even look at ground speed for momentary bench marks.

            But never mind- to use any sort of intelligent thought is verboten...one must only, blindly regurgitate the FCOM...

            To hell with Airbuscrew who is a master of regurgitation, type-rated, and has a degree in aeronautical engineering, even though he's not ass smart as Gabriel...
            Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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            • #21
              Originally posted by 3WE View Post
              To hell with Airbuscrew who is a master of regurgitation, type-rated, and has a degree in aeronautical engineering, even though he's not ass smart as Gabriel...
              If that's in reference to me, my degree is in business (albeit with an aviation emphasis). I'm nowhere near smart enough for engineering, aeronautical or otherwise.

              Comment


              • #22
                Originally posted by Evan View Post
                At what weight? For a target speed of .78M, the QRH calls for a range from -0,5° to -2.5° for descent. Not 0* BTW.
                Sounds like you're looking at a 321 chart, or maybe an old 320 chart. Either way, my QRH for A320 gives a target of .76/275kias transition of between, you guessed it, 0 and -1.5 (not -2.5) AND. So, yeah, Airbus (not me) says that descent is safely within the envelope at 0 pitch and idle. At least that's a great place to start while the PM is looking up the chart.

                Comment


                • #23
                  Originally posted by ATLcrew View Post
                  Sounds like you're looking at a 321 chart, or maybe an old 320 chart. Either way, my QRH for A320 gives a target of .76/275kias transition of between, you guessed it, 0 and -1.5 (not -2.5) AND. So, yeah, Airbus (not me) says that descent is safely within the envelope at 0 pitch and idle. At least that's a great place to start while the PM is looking up the chart.
                  These upper-level UAS things almost always (perhaps always) occur in close proximity to unstable convective weather systems. What happens when you hit unstable air while descending, have extreme difficulty maintaining a given pitch, or maybe even reading the PFD?

                  One thing highlighted by AF447 was the relatively unknown phenomena of cruise-level ice ingestion—essentially the presence of ice where ice is not supposed to form. It was becoming known that convective weather systems could elevate warm air and ice crystals into altitudes where ice typically doesn't exist. Prior to the incidents studied by the investigation, unreliable airspeed was considered a lower altitude phenomena, present where temperatures were warm enough for moisture to exist and ice to form. While UAS at cruise was unheard of, UAS at lower altitudes, often in ascent and descent, was a known issue.

                  So here we have a crew who has experienced UAS at cruise and opted to descend into warmer air where ice is more likely to form and UAS is more common. In doing so they risk losing their speed reference as they transistion altitude, TAT, air density and potential turbulence or wind shear. Why? Why not simply follow the memory items and QRH values for steady, stable flight at your present flight level, at least for several minutes?

                  That's what I'm asking. I'm not looking for a list of reasons why you might descend, I'm looking for one good reason why you wouldn't rather stay at flight level and ride it out. Almost all pilot error crashes involving upset occur in transitional phases of flight, particularly under manual control. Almost none occur in steady, stable ones (both AF447 and Colgan resulted from pilot-induced departure from stable flight).

                  In any event, the correct thing to do is the safest course of action. When is remaining in stable cruise-level flight with UAS not the safest course of action?

                  My guess: the crew wasn't well-trained on UAS phenomena and procedure.

                  Comment


                  • #24
                    Originally posted by Evan View Post
                    These upper-level UAS things almost always (perhaps always) occur in close proximity to unstable convective weather systems. What happens when you hit unstable air while descending, have extreme difficulty maintaining a given pitch, or maybe even reading the PFD?
                    If there was enough precip at FL370 to ice up the tubes (again, if that's what actually happened), I'd be fairly confident that they were in plenty of chop as well. In other words, they were already in "unstable air". I'd rather be in unstable air on my way down to where performance is plentiful rather than stay where it's marginal. Especially, if, as you yourself suggested, I'm having difficulty maintaining pitch or even reading the instruments. I don't want to hang out at 370 where tiger tail to barber pole is all of 20kts without protections or a good IAS in that circumstance. I'd much prefer to get down to where even if I can't maintain a given pitch rate, it won't kill me. So, there's your one good reason. And again, for all "we" know, they did stay level for several minutes before heading down.

                    Remaining in stable cruise level flight with UAS is not the safest course of action when you're not sure you can maintain it without either overspeeding or underspeeding, as I've already explained to you.

                    If you want to throw this crew under the bus just cause you feel like it, that's your business, but I really think you're barking up the wrong tree here.

                    Comment


                    • #25
                      ATL, I disagree. While I don't see anything dangerous about descending in a known and controlled pitch/thrust setting, unless you are getting yourself into the anvil of a Charlie Bravo, I don't see any of the dangers you imply about staying up there and applying the memory item pitch and thrust.

                      The distance between the tiger tail and the barber pole is not 20 knots. It may be 20 knot INDICATED (or equivalent, or calibrated, or computed, which are all more or less the same). You may be doing 230 kts CAS. But, at FL370, the actual speed, the TAS, the one that counts for dynamics not aerodynamics, is nearly twice as much, so your 20 knots gap is more a 35 kts gap.

                      But most important, if you follow the 5deg CLB, you will not be enforcing a trajectory or a performance. You will be doing P+P=P. You will set the pitch and the power and let the performance accommodate itself. Because you were likely not flying at 5 deg, the result of setting 5 deg will be a climb (a 2 to 4 degree climb if your pitch was initially 1 to 3 degrees). There will be initially no change in AoA (which was 1 to 3 degrees), except a brief and small increase when you pitch up until the plane establishes itself in the climb (a couple of degrees and seconds max). Now, chances are the excess power between whatever you had set and CLB will not be enough to sustain the climb, so the plane will climb a bit, slow down and settle at level flight with a 5 degrees pitch, which is a 5 degrees deck AoA, which is more than typical (and hence slower than typical and slower than you were originally doing) so you will never overspeed. At the same time, 5 degrees AoA may be more than typical but it is still far from stall. Again, don't worry about the coffin corner. The A320 (as any modern airliner) run out of engine before running out of wing. By flying P+P and leave the =P open to what ever P+P provide, and keeping sound and proven values of P+P, you are guaranteed remaining within the envelope, at the expense of not enforcing the altitude or the climb/descent rate. Now, sound P+P can be 5+CLB, 0+IDL, or keep you hand off the controls and let HAL 9000 handle it.

                      Actually, that might be a first initial choice. Don't touch anything, breath deeply, count to 3, asses the situation, scan the instruments to check which ones agree across the board. If it is UAS, you will be in alternate law which is still G-on-stick, so leave the power as it was (it will be locked after the UAS, until you take the levers out of CLB), and the stick neutral will keep 1 G and hence a level flight, if that is what you had below. Super minimal stick input is acceptable to keep the VSI at zero (average, let it ride on the turbulence, do not overcompensate). Do take a mental note of what the pitch was. If for any reason the AT increased or decreased the thrust in the last moments before the UAS (to compensate for a speed deviation from target), the thrust may be too low or too high and the speed may be decreasing or increasing so, unlike a Boeing that is speed stable, HAL will increase or decrease pitch (and AoA) to keep 1G and level flight. If this happens you might want to adjust the thrust. Or better, you might decide at that moment that it is good to go 5+CLB until your buddy pulls that charts, something that he should be already doing anyway.

                      Level flight helps a lot with the awareness of AoA (given that you guys typically don't have an AoA indicator even when this data is getting collected and used in the internal HAL calculations), because pitch = AoA. So holding a slightly higher than usual pitch / AoA but well away from stall AiA ensures a slower than usual flight (hence no overspeed) and no stall. If anything, a shallow climb (that may result from the 5+CLB) will mean an AoA below 5 deg. On the other hand, whenever the VSI is negative will mean an AoA higher than the pitch by the descent slope. And that's hard to tell. I will be quite worried for a couple of thousand feet per minutes or more. It is somehow tough to mentally calculate the slope, but from ILS landings you remember the rule of thumb that a VSI = speed/2*10 = 3 degrees (for example, 140 kts/700fpm) you can get an idea, just an idea because you lost the speeds, remember? Just remember to take the TAS, not the CAS/IAS. If you were in the 450 / 500 KTAS range, then a VSI of 2200/2500 fpm will give you a 3 degrees slope. 3000ish will be 4ish degree slope, so you need to add that to the pitch to get an estimate of the AoA (that will be 4 degrees if you keep the pitch at zero).

                      In short, if I had no UAS procedure, what I would do from airmanship alone is to keep the cruise pitch that I was holding bfore the incident and leave the thrust as it was, and do only very minor adjustments in pitch (to keep the pitch against HAL desires to keep the altitude instead of the pitch) and in power (to keep 0 FPM average). And that may even be the legal procedure if there is no immediate concern (i.e. the 5+CLB memory P+P is not mandatory), while we give a minute to the UAS to clear itself while the pilot monitoring pulls the manuals and the pitch/thrust tables. I agree with Evan that I would try not make any transitions. The plane was flying well with the weight, OAT, altitude, pitch and power that it had just before the event and will keep it doing so during the event. Mr Newton, Bernoulli, Navier, Stokes and Match don't know if the ASIs are working and agreeing or not, so for the same conditions they will keep the same forces and moments.

                      Finally, in these ITCZ events, these small ice crystals were found in clear air thousands of feet above the clouds and miles away laterally, taken there by the convective air currents (together with the warm air from below). It is not ice forming and accreting in the pitots (for which you need visible humidity), for that you need super-cooled water, but ice already formed in the air accumulating in the pitots. AF encountered light to moderate turbulence at most (at least before and during the initial phase of the incident, before the stall), nothing out of the ordinary. A descent into the core of the convective weather can be more problematic. And this was a large descent of 12000ft, but maybe they were monitoring the radar to avoid yellows and reds.

                      --- 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


                      • #26
                        Originally posted by Gabriel
                        In short, if I had no UAS procedure, what I would do from airmanship alone is to keep the cruise pitch that I was holding bfore the incident and leave the thrust as it was
                        AF447 was apparently in enough chop to prompt the PF to set a reduced speed on the FCU. Not severe, but significant. I think it is fair to presume that this will often be the case with UAS incidents at cruise and thus we can expect other crews to do the same (you might have done this in your example). That means if you leave the thrust where it is, you will be decellerating and locked at an inadequate power setting. If I remember correctly, AF447 was locked around 75% N1 where it needed about 98%. I agree with everything you are saying except for this. You need to move the thrust levers before they are forgotten (although the message will remain at the top of ECAM).

                        Comment


                        • #27
                          Originally posted by Evan View Post
                          Originally posted by Gabriel
                          In short, if I had no UAS procedure, what I would do from airmanship alone is to keep the cruise pitch that I was holding bfore the incident and leave the thrust as it was
                          AF447 was apparently in enough chop to prompt the PF to set a reduced speed on the FCU. Not severe, but significant. I think it is fair to presume that this will often be the case with UAS incidents at cruise and thus we can expect other crews to do the same (you might have done this in your example). That means if you leave the thrust where it is, you will be decellerating and locked at an inadequate power setting. If I remember correctly, AF447 was locked around 75% N1 where it needed about 98%. I agree with everything you are saying except for this. You need to move the thrust levers before they are forgotten (although the message will remain at the top of ECAM).
                          That is why the part that you cut and quoted was immediately followed by...

                          and do only very minor adjustments in pitch (to keep the pitch against HAL desires to keep the altitude instead of the pitch) and in power (to keep 0 FPM average)

                          --- 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


                          • #28
                            Originally posted by Gabriel View Post
                            That is why the part that you cut and quoted was immediately followed by...
                            I know but remember it's a stealth thing on the Airbus, an awareness issue. With no backdrive, those levers will remain fully in the CL detent and the only way you are going to notice the actual reduced power setting is the donuts on the ECAM gauges. Easily overlooked in that situation. That is probably why the ECAM message to move those levers is a blue actionable item that remains at the top until it is cleared. HAL wants it done. And I won't even bother with the FD issue...

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                            • #29
                              I am holding the pitch and watching the altitude/VSI, ok? If the altitude starts to go down while holding the pitch constant in its initial value, I will add thrust. At that point I will need to move the thrust levers, no matter if it is a Boeing or an Airbus or if the thrust was locked or not.

                              --- 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


                              • #30
                                I can't speak to the Airbus numbers that are being thrown around, but I can tell you that the Power and Pitch numbers for my fleet and airline were chosen to provide a gentle descent at high flight levels and a gentle climb at low altitudes......and they're the same numbers regardless of altitude (75%N1/2.5 Nup clean or 75%N1/6.0 Nup with flaps). Were you somehow under the impression that a given power/pitch setting was going to provide a perfect level flight under all conditions?

                                Either way, this can be summed up thusly. Crew encountered serious malfunction. Crew stabilizes situation and handles malfunction. Crew lands safely and pax go on to fruitful lives. Seat 22B know-it-alls explain how they would have provided an even better outcome.
                                Parlour Talker Extraordinaire

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