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Volaris A321 loses both ELACS

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  • #16
    Originally posted by ATLcrew View Post
    3. A deferred ELAC is a lot more common that a deferred Radalt.
    How common? Failure of both ELAC's is a very serious condition. Going with one presents zero redundancy for a lot of key functions (autoflight, envelope protections, ailerons...). I'm surprised to learn it is common at all.

    All I was pointing out there is that there are a lot of other failure conditions that are contingent on both ELAC's functioning for dispatch. Thus, I employed the word 'shipshape' which is a jaunty expression of nautical origin that I assumed everyone would understand. I should stick to aviation terms...

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    • #17
      Originally posted by Evan View Post
      How common? Failure of both ELAC's is a very serious condition...
      Not very common, but it happens, and no, dual ELAC failure is not, in my opinion, all that serious. The airplane is perfectly manageable in that condition, at least by a professional crew. You make it sound like it's the sort of failure that would cause the sky to fall and the sun to extinguish, and that's just not the case. Just like the crew in the original incident, we'll go through the COM, set the silly thing down, write it up, and proceed to the nearest Fourbucks for a latte.

      Didn't realize you were also an expert in nautical matters, my apologies.

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      • #18
        Originally posted by ATLcrew View Post
        Not very common, but it happens, and no, dual ELAC failure is not, in my opinion, all that serious.
        Are you serious?!! Losing autoflight and normal law, not that serious?!! We've seen what can happen to crews inexperienced with manual flight under these reversion modes, not to mention the sudden workload during transition with a cascade of system failures. Yes, it SHOULD be manageable by a well-trained crew with good situational awareness (as it was here) but that's not always the case is it? It's a strong catalyst for a chain of events. I didn't call it catastrophic, I called it serious, and it is to taken very seriously. As in, it should never happen.

        If one ELAC was MEL'd and then the second dropped out, I can understand that as a remote possibility. If they both failed in flight, I'll be damned...

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        • #19
          Originally posted by Evan View Post
          Are you serious?!! Losing autoflight and normal law, not that serious?!!
          It shouldn't be that serious. If it is, then I call it a design issue (not the failure itself, but that it becomes so serious).

          Why? Because loss of autoflight and normal law can happen for a number of reasons, loosing both ELAC being perhaps the least common. How about unreliable airspeed? You loose not only autoflight and normal law but also.. airspeed. And this is a relatively common occurrence. I already forgot how many cases we had just in the A330/340 before AF (and ALL of them were poorly managed).

          If loosing autoflight and normal law (with all the flight instruments and flight controls working) is serious, then I want autonomous pilotless airplanes NOW!

          Or, alternatively, put PILOTS in the cockpit. Not something else. Because if a person cannot hand fly the plane with all things basically working ok, then they don't deserve be called pilots.

          --- 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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          • #20
            Originally posted by Gabriel View Post
            It shouldn't be that serious. If it is, then I call it a design issue (not the failure itself, but that it becomes so serious).

            Why? Because loss of autoflight and normal law can happen for a number of reasons, loosing both ELAC being perhaps the least common. How about unreliable airspeed? You loose not only autoflight and normal law but also.. airspeed. And this is a relatively common occurrence. I already forgot how many cases we had just in the A330/340 before AF (and ALL of them were poorly managed).

            If loosing autoflight and normal law (with all the flight instruments and flight controls working) is serious, then I want autonomous pilotless airplanes NOW!

            Or, alternatively, put PILOTS in the cockpit. Not something else. Because if a person cannot hand fly the plane with all things basically working ok, then they don't deserve be called pilots.
            Gabriel... UAS is serious. Loss of autoflight in RVSM is serious. Loss of any system that alters control law is serious. Did I say catastrophic, dire, fatal? Of course not. I said manageable. But 'manageable' introduces the possibility of catastrophic mismanagement... as we have seen. These things are serious because they can degrade SA and be misinterpreted. They are serious because now you are essentially flying a different aircraft than the one you are used to.

            From the standpoint of aviation safety, loss of both ELAC's is a serious incident and it should never happen. It's a no-go situation. It is serious enough for a return or diversion. It is a serious failure condition that has the potential to become a catastrophic sequence of pilot error.

            Is it a design problem? I don't think so. I think it's a policy problem at best. Since losing one ELAC leaves no redundancy for a fault-passive system, I question the wisdom of having it on the MMEL as a go item. But, what are the odds of losing the other one a short time later. Probably extremely remote. Which is why this incident caught my eye and perplexes me. If the aircraft had been flying for an extended number of cycles with one ELAC out, it would seem more plausible. But the AV Herald entry makes it sound as if both failed inflight. THAT might be a design problem...

            That's what I'd like to know.

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            • #21
              Hmmm...ATL crew is saying some interesting things...(of course, he usually does)

              ...am I hearing that when you turn off all the computers you have something that behaves sort of like an airplane? (God forbid! /sarcasm) And that if you have all that fundamental BS tucked away not too far back in your head (and a few official checklists that you competently execute) that you start flying it like a plane.

              Again...shocking!
              Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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              • #22
                I'm just wondering how this happens on a BRAND NEW airplane...

                Airbus A321 - MSN 6601 - XA-VLJ
                Airline Volaris
                Serial number 6601
                Type 321-231
                First flight date 07/05/2015
                Test registration D-AVXM
                Plane age 0.3 year

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                • #23
                  Monday morning hangover crew.

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                  • #24
                    Originally posted by 3WE View Post
                    ...am I hearing that when you turn off all the computers you have something that behaves sort of like an airplane?
                    Yes, but sort of not like a Title 14 § 25.171 certified transport category airplane. (high and low speed protection are still there as 'reduced protections' but there's no alpha floor and no high AoA protection, two things that allowed Airbus around the above FAR's).

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                    • #25
                      Originally posted by Evan View Post
                      Yes, but sort of not like a Title 14 § 25.171 certified transport category airplane. (high and low speed protection are still there as 'reduced protections' but there's no alpha floor and no high AoA protection, two things that allowed Airbus around the above FAR's).
                      Never flown with computer-assisted alpha protection and have lived to post about it.

                      But, as you should be aware by now, staying around known healthy airspeeds and known healthy attitudes and known healthy power settings, usually provides really damn good alpha protection on most all airplanes, regardless of what the FCOM says for a number of different computer malfunctions...

                      Yeah, it's just cowboy stick and rudder stuff, but hey, sometimes dual ELACSs failures (and other excrement) transpire(s).
                      Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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                      • #26
                        Originally posted by 3WE View Post
                        Never flown with computer-assisted alpha protection and have lived to post about it.
                        Never flown on an Airbus or 777?

                        Originally posted by 3WE View Post
                        But, as you should be aware by now, staying around known healthy airspeeds and known healthy attitudes and known healthy power settings, usually provides really damn good alpha protection on most all airplanes, regardless of what the FCOM says for a number of different computer malfunctions...
                        So we should do away with Title 14 § 25.171?

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                        • #27
                          Originally posted by Evan View Post
                          1. Never flown on an Airbus or 777?



                          2. So we should do away with Title 14 § 25.171?
                          1 Flown on is not what I said. But if we are flying on airplanes (i.e. riding) then I also have quite a few hours riding without computerized alpha protection (where the plane's ATP's used ASI's and AI's and various power gauges...some steam gauges, some flat panel displays), and to the best of my knowledge, I never experienced an overly-precarious alfa...

                          ...it sure FEELS impressive right after takeoff, but then again, somehow the plane is kept at a healthy, known attitude and healthy known airspeed for the very high power setting.

                          2. Sorry, I have not memorized cryptic references such as that.

                          I don't think they are much help when I try to maintain healthy attitudes, airspeeds and power settings...and, to date, my record is better than at least a few people who probably did know what you were talking about.
                          Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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                          • #28
                            I think he's referring to the requirement that aircraft meet various requirements dictating stability and controllability under various circumstances.

                            If you pull back relentlessly in a 172 it will eventually hit the ground hard but you really have to work to make it happen - the aircraft's aerodynamics and other factors like CG make it hard to stall and very "nicely behaved" when it does.

                            If an aircraft for whatever reason flips into a fully developed flat spin 250 milliseconds after pulling back on the yoke too hard, they're either going to have to fundamentally redesign the airplane (and possibly compromise other factors they don't want to compromise) or add some computerized magic to tame the a/c's bad habits. The result can be a fine aircraft... until the computerized magic quits working.

                            In spite of the tone of the above, I'm not necessarily saying that computerized magic is bad... simple mechanical things like reversed elevator cables have caused people to become dead in old-school Cessnas. Different hardware just yields different failure modes which must be dealt with differently.
                            Be alert! America needs more lerts.

                            Eric Law

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                            • #29
                              Originally posted by elaw View Post
                              I think he's referring to the requirement that aircraft meet various requirements dictating stability and controllability under various circumstances...big deletion just for brevity...
                              Thanks for the clarification and Indeed...

                              ...if the computer fails, perhaps the pilots need to be a little more careful at maintaining those healthy known attitudes and healthy known airspeeds at healthy known power settings, because, if they mess those up, the resulting loss of control might be much uglier.

                              ...I might even make a point to run through a memory checklist from the FCOM, as long as it does not interfere with Broadly Applicable Cowboy Fundamental #1, "Aviate".
                              Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                              Comment


                              • #30
                                Originally posted by 3WE View Post
                                ...it sure FEELS impressive right after takeoff, but then again, somehow the plane is kept at a healthy, known attitude and healthy known airspeed for the very high power setting.
                                I don't think you're quite getting it.

                                1) Read the FAR Title 14 § 25.171 and 25.173 and 25.175 for that matter.
                                2) Read the A320 FCOM Chapter 1.27
                                3) Realize, "Hey, according to the FAR's this thing ain't even airworthy!"
                                4) Then read the history of how Airbus certified an aircraft that did not meet the criteria as described in the FAR's by offering alternate criteria.
                                5) Notice that in the scenario where both ELAC's have failed and most of the envelope protections are lost, the aircraft no longer meets the alternate criteria either. Hence, from an airworthiness certification standpoint, it is now unsafe to operate as a transport category aircraft and must be landed ASAP.
                                6) Tell me that is not a serious situation that should really never happen.
                                7) Ask yourself, "so how the hell did this happen?" Then we're on the same page.

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