Air France 447 Mystery Solved

Discussion in 'General Discussion | Travel' started by MX, Jun 7, 2012.  |  Print Topic

  1. MX

    MX Gold Member

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  2. autolycus

    autolycus Gold Member

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    anabolism and mtlfire like this.
  3. HaveMilesWillTravel
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    HaveMilesWillTravel Gold Member

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    The ABC News headline has a question mark at the end -- has there been an official finding of the cause yet?

    "Air France Plane Crash Mystery Solved?"
     
  4. MX

    MX Gold Member

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    The original Nightline half-hour broadcast indicated that it was based on the concluded investigation. But ABC website divided up the original content into several small clips. The links that I posted may not cover the entire program.
     
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  5. HaveMilesWillTravel
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    Wikipedia says the final report will be released on July 5th 2012.

    http://en.wikipedia.org/wiki/Air_France_Flight_447
     
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  6. anabolism
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    anabolism Gold Member

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    I think it's misleading to say "the pilots are at the controls for only three minutes: 1:30 on takeoff and another 1:30 on landing." "At the controls" is not the same as "hand-flying."

    More to the point, I'm not a pilot, so I'm sure I don't understand things, but it's always seemed to me that Boeing took the right approach to fly-by-wire design: make it look and feel like fly-by-hydraulics. The physical feedback can be important. For example, when one pilot is moving the stick in the opposite direction, the other pilot feels the increased resistance. Airbus took a different approach that changes the UI from a traditional pilot's to a more generic computerized UI (with joystick and keyboard input). If I recall correctly, there have been crashes from UI confusion (e.g., a pilot confusing angle of descent with rate of descent).

    More fundamentally, who could think that if two pilots are providing different control inputs (stick up vs down), that the correct response is to average them? Only a software engineer (and likely a fairly junior one) would think this is the right thing to do. Virtually any other response (e.g., pick one, reject both with an error message and noise) would be preferable.

    There's also the more philosophical debate as to if the flight control software should enforce safe parameters or if the pilots should be allowed to exceed normal ranges. Good arguments have been made for both approaches, so I can't fault Airbus for picking one while Boeing picked the other.
     
  7. HaveMilesWillTravel
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    HaveMilesWillTravel Gold Member

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    I have to believe that Airbus isn't leaving design decisions such as this to junior software engineers... or software engineers at all. I am one, not for Airbus, and we certainly don't make any decisions as to the functional behavior of the product for, say, an accounting system. That's the responsibility of the domain experts (eg product mangers where I work). I am not an accountant and I won't make up any rules when I implement accounting functionality.
     
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  8. anabolism
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    anabolism Gold Member

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    Well, that's my point. I find it inconceivable that a domain expert in aviation would decide that the right thing to do when the two pilot inputs conflict is to average them. Perhaps someone who, unlike me, is a domain expert in aviation would say "sure, that's the right thing to do," but so far, it seems like the sort of choice that only a software engineer would make, perhaps deep in the code in the middle of the night, just one of tens of thousands of choices the software makes, figuring to just code it some way, any way, for now, and it'll get reviewed and fixed later.
     
  9. FlyingBear
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    FlyingBear Silver Member

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    They are supposed to work in tandem, so averaging out makes sense, since inputs cannot be absolutely the same. It can also be easily argued that if you have two opposite actions, you are thus avoiding any one extreme and forcing the pilots to start working in tandem again.
     
  10. viguera
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    viguera Gold Member

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    I can see averaging inputs within a certain range, but there has to be a threshold where you say "wait, something's not right here" when the inputs are wildly dissimilar, or even conflicting.

    But there's no easy answer there... it makes sense that the captain's chair has command authority and if the inputs are within a certain threshold you average, otherwise you ignore anything that's not coming from his controls.

    But what happens then when the captain -- or the person in that seat -- is obviously wrong though? Do you trust the software to make the "right" decision and override the inputs? Like I said, not an easy answer.
     
  11. Gaucho
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    Gaucho Gold Member

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    JBCarioca needs to be on this thread..... a former flight instructor of birds hard to fly, he is..... ;)
     
  12. anabolism
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    anabolism Gold Member

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    Are they supposed to work in tandem? I thought that only one at a time was supposed to be operating the controls.
     

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