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Thread: Breaking news: Ethiopian Airlines flight has crashed on way to Nairobi

  1. #1001
    Senior Member 3WE's Avatar
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    Answer:

    Quote Originally Posted by Gabriel View Post
    Yes
    Thank you. (Additional verbiage is OK too)

    Not_Answer:

    Quote Originally Posted by Gabriel
    "All RJ's now have FBW and autothrottles" + suggestions for Nervocalm.
    Sugerencia para píldoras que mejoran la comprensión & eventual red font.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  2. #1002
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    Quote Originally Posted by Evan View Post
    Blah Blah Blah
    Not sure I totally agree, but will only bet a single beer, recognizing the risk that I might be the one buying.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    I pointed out that the knowledge required to pilot the aircraft of the present and of the future require a more complex array of traditional airmanship and systems admin expertise. There will be more complexity in understanding these systems and how they alter pilot action requirements and automation behaviors in varying degrees of degradation, when one or more components fail or malfunction. The skill set required to be a pilot will have to involve a strong aptitude for systems.

    [...] a complex knowledge is still required here. For one thing, the transition requires a good understanding of what is lost, how it will affect handling and flight control and what pilot actions are now necessary (such as manual pitch trim or thrust-lock on the A320). For another, the goal of reconfiguration laws is not to remain in manual flight with degraded protections, it is to allow the crew to continue flying while working the problem and restoring systems and autoflight. This is especially true of the direct law and purely mechanical backup levels. Thirdly, in degraded states, pilot commands may still be blended with automated ones in different ways then they are used to under normal conditions and things like flight directors may still be functional but not reliable. Crews must understand and anticipate this.

    I was talking about an increasingly complex understanding of the aircraft, not the physical complexity of the aircraft itself (which may become reduced by technology). I was talking about how, as ever-higher efficiency is demanded from protected aircraft, that efficiency and protection may come from systems such as augmented stability and conditional command interventions. It will come from systems that provide exacting flight surface control beyond human capability. It might even come from wing designs that can reconfigure across their surfaces in much more complex ways. As these systems are added, pilots will have to have a greater systems-side mastery to cope with failures. All of which means the standards for recruiting, vetting and training pilots will have to evolve and the job itself might require a much different mindset with different strengths and talents than those of the past.
    Again, I don't think this will be the path that airliners design will take in the future. Think FADEC. FADEC sorts all issues internally, or it doesn't work. There is no way for a pilot to turn switches or pull breakers to "reconfigure" the FADEC, and there is no automatic internal reconfiguration in the FADEC that ends up with the FADEC working identically from the pilot point of view, or not working at all. Pilot's don't need to understand how the different computers, sensors and other inputs (like the thrust levers position) interact for the FADEC to produce the output it does. There is no FCOM that describes how the FADEC work and what will it do in different failure scenarios. For example, nowhere is it explained that if the FADEC senses an uncommanded reduction in fuel flow it will open the fuel metering valve beyond the normal setting for the required thrust, and that that will not be reflected in a movement of the thrust lever position (even in a Boeing). Oh, and the pilots don't complain that this is not explained, as they did complain of the MCAS, and rightfully, because the MCAS is not self-enclosed and self-troubleshooting like the FADEC. The FADEC has no equivalent to the "cutout switches" that will give you manual control. The pilots DON'T NEED TO KNOW how it works, because the FADEC work out its issues internally with no pilot intervention, doesn't change its behavior (from the pilot's point of view) when doing so, and if it does so incorrectly or what it does is not enough, there is nothing that the pilot can do anyway.

    I think that the design philosophy of the whole airplane will be headed in the same direction. Except:
    - Perhaps with 1 intermediate status between "working" and "not working", which would be a friendly Cessna like (or 747-200 like) direct law coupled with raw flight parameters and raw navigation (but you still can have a simple autoflight, like a Cessna does).
    - Critical information regarding system degradation (with NO performance degradation, but with risk of performance degradation if further system degradation occurs) relayed to the pilot so he can calmly make an informed diversion decision.

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  4. #1004
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    Again, I don't think this will be the path that airliners design will take in the future. Think FADEC. FADEC sorts all issues internally, or it doesn't work.
    I don't think FADEC is a perfect metaphor for flight control systems. There are fewer interdependencies and thus fewer failure ramifications. It is also very robust. On the A320, an ENG 1(2) FADEC A (B) FAULT is passive situation, since the B channel simply takes over without ramifications. But an ENG 1(2) FADEC FAULT (where both channels have failed) does have ramifications that pilots need to be aware of.

    On the A320, when you lose FADEC, you lose N1 and N2 limit protections. You lose automated control of engine thrust ratings. You lose automated acceleration and deceleration scheduling. You lose bleed valve scheduling. And then there are system interdependencies. How does an EIU fault affect FADEC? How does an LGCIU fault affect FADEC?

    I get your point about it being all or nothing (if both channels fail). Again, I'm not suggesting that we need to add complexity that allows pilots to start reconfiguring systems in flight beyond what is necessary. I'm just pointing out that, when the systems are designed to reconfigure, the pilots need to know (or have quick reference to) all the ramifications of those reconfigurations.

  5. #1005
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    Quote Originally Posted by Evan View Post

    On the A320, when you lose FADEC, you lose N1 and N2 limit protections. You lose automated control of engine thrust ratings. You lose automated acceleration and deceleration scheduling. You lose bleed valve scheduling. And then there are system interdependencies. How does an EIU fault affect FADEC?
    Easy there, cowboy. Which engines are we talking about? Which mod status? Also, this is the first time I've ever seen the term "scheduling" used as regards bleed valves. For that matter, which bleed valves are we talking about?

  6. #1006
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    I don't think FADEC is a perfect metaphor for flight control systems. There are fewer interdependencies and thus fewer failure ramifications..
    And that's where the added complexity of the systems and their integration and, communication and interaction (which again adds a lot of complexity) comes into play.
    The FADEC has been FA and D since the 70's if I am not mistaken, So we are 40 years ahead of that with the technology. The reliability, speed, capability and memory capacity of the electronics has multiplied many-times-fold since then.

    I have no doubt that the technology and engineering capacity exist TODAY (or 10 years ago) to make it happen.
    I suspect that it did not happen mostly because or regulatory burden and liability issues (if the pilot f-up in a reasonable good design, we will not be liable, if the computer kills everybody on board because of a design or reliability issue we will be liable, even if that happens 1/100th of the times that everybody dies because a pilot f-ups in situations where this technology would have saved the day).
    But there is a point where the steep needs to be taken, An I think that we are reaching this point.

    Again, I'm not suggesting that we need to add complexity that allows pilots to start reconfiguring systems in flight beyond what is necessary. I'm just pointing out that, when the systems are designed to reconfigure, the pilots need to know (or have quick reference to) all the ramifications of those reconfigurations.
    The thing is that we need to add complexity behind the scene to get a simple user interface and a better self-enclosed robust solution. The reconfiguration should have no ramifications other than the added risk because you lost some redundancy. Just like in a multiple-channel FADEC.

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  7. #1007
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    On the A320, when you lose FADEC, you lose N1 and N2 limit protections. You lose automated control of engine thrust ratings. You lose automated acceleration and deceleration scheduling. You lose bleed valve scheduling. And then there are system interdependencies. How does an EIU fault affect FADEC? How does an LGCIU fault affect FADEC?
    If you loose the FADEC (both channels) for a given engine, you've lost control of the engine. Either the engine will self-shut down or it will keep at a constant fuel metering valve setting, constant stator vanes position, constant bleed air doors setting, etc. t that point the only control you have is cut the fuel and shut it down.

    BUT, the plane can be designed to keep working with automatic thrust, automatic acceleration and deceleration schedules, etc. An engine failure can be made almost transparent for the pilot. Of course he will need to consider that his service ceiling and go-around climb gradient are lower, and that if he looses another engine he is in a glider.

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  8. #1008
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    If you loose the FADEC (both channels) for a given engine, you've lost control of the engine. Either the engine will self-shut down or it will keep at a constant fuel metering valve setting, constant stator vanes position, constant bleed air doors setting, etc. t that point the only control you have is cut the fuel and shut it down.
    I recall the situation with Quantas Flt 32, where the data signal from the thrust levers to the FADEC was severed and the engine remained at its current thrust. I thought it was designed to go to flight idle or even shut down, but then again, that wasn't actually a FADEC failure. In any case, not ideal.

    BUT, the plane can be designed to keep working with automatic thrust, automatic acceleration and deceleration schedules, etc. An engine failure can be made almost transparent for the pilot. Of course he will need to consider that his service ceiling and go-around climb gradient are lower, and that if he looses another engine he is in a glider.
    Yes, but it sort of already is, since the thing has dual, redundant channels. I'm not aware of a case of dual channel FADEC failure. Perhaps a single channel is a MEL item and the second channel failed? I don't have any precedent fo that. Maybe you do...

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