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    [QUOTE=EmanuelGoldstein;3362079]
    I dunno, but he does have a $500,000 boat that he bought with his airline pilot earnings ...

    Money not equal to brains, or flying skill. I'd be more impressed if he actually was *flying* one of those planes
    right now. Except ooops, they're still grounded. While they work on the 'software update.'

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    Default Boeing 737 Max

    Wouldn’t it have been simpler for Boeing to fit longer landing gear on the 737Max, raising the height from the ground, allowing the new, bigger engines to be mounted in the standard position on the wings?

    As I understand it, Boeing had to mount the larger engines higher on the wing (as the 737 sets low to the runway), creating the unwanted flight characteristics that MCAS is supposed to neutralize.

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    Quote Originally Posted by cnctoolcat View Post
    Wouldn’t it have been simpler for Boeing to fit longer landing gear on the 737Max, raising the height from the ground, allowing the new, bigger engines to be mounted in the standard position on the wings?

    As I understand it, Boeing had to mount the larger engines higher on the wing (as the 737 sets low to the runway), creating the unwanted flight characteristics that MCAS is supposed to neutralize.
    Longer landing gear would have been a huge engineering change. Besides the longer gear themselves, there would have to be larger compartments, which probably means moving a bunch of ancillary machinery around, as the landing gear compartments are usually very busy and crowded places.

    Regards.

    Mike

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    and remember that the contact points change on landing in regards to overall center of mass of the plane, so there would other changes required to overall design, not just bigger landing gear wells, and longer gear - more mass, not just the weight of the added length, but longer leverage will affect everything around it, which will have to handle larger dynamic loads etc.

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    I am pretty sure boeing never intentionally cut corners.

    They cut some corners through corp. culture, like most big corps do, especially in the us.
    In the eu and asia cutting corners on safety/air happens less, as jail and major corporate penalties are (much) more likely.

    The add-on system was meant to be helpful, and also meant to reduce the need to re-train pilots - thus more sales.

    The original intent was good, and large numbers of simulations and thousands of successful uses show that the system mostly works well, as intended.
    In some small number of cases the system caused the crashes.
    Because it was not good enough, in less than 1% of cases, unforeseen.

    Boeing did not build a shoddy, bad, cut-rate system.
    They simply made an engineering error.

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    Maybe they should have started with a clean sheet of paper and designed an entirely new aircraft ?

    Regards Tyrone.

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    I understood the 737 sits low to the ground so it can be used at smaller airports with stairs not the long tunnels at a much greater height.
    Bil lD.

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    Quote Originally Posted by Bill D View Post
    I understood the 737 sits low to the ground so it can be used at smaller airports with stairs not the long tunnels at a much greater height.
    Bil lD.
    I think the main gear length is limited by the fact that the trunion is mounted on the wing inboard of the engine pylon and it can't be any longer or the tires won't clear the structural beam that separates the left and right wheel wells with the gear retracted. They could have designed a complicated folding strut, but that would have its own set of trade-offs.

    The nose wheel strut on the Max is longer than on the NG airplanes to provide more ground clearance for the engine nacelles.


    Sent from my SAMSUNG-SM-G930A using Tapatalk

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    Quote Originally Posted by jim rozen View Post
    Sounds good. What do you suggest when the manufacturer of the machine deliberately hides the
    flight characteristics, like Boeing did?

    Boeing 737 Max Simulators Are in High Demand. They Are Flawed. - The New York Times

    "Oops we made a boo-boo." They learn, the passengers die.
    That's the history of transportation in a nutshell. Or machine work, scuba diving, bridge building....

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    Quote Originally Posted by jim rozen View Post
    Money not equal to brains, or flying skill. I'd be more impressed if he actually was *flying* one of those planes right now.
    Sheesh. Let me spell this out. He made the money first as a pilot then as an instructor pilot flying commercial aircraft. According to him (I have no way to check but have no reason to doubt) at one time he had the highest number of hours in a 737 of anyone in the country.

    He is certainly capable of discussing many aircraft-related subjects in detail. And I'm pretty good at sniffing out bullshit. I'll take that over some guy on the internet ...

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    Quote Originally Posted by EmanuelGoldstein View Post
    Sheesh. at one time he had the highest number of hours in a 737 of anyone in the country.
    When I was a young F/O I worked with a Captain who had the most hours on a DC9 in the world, over 20K IIRC.

    Now they talk about Captains having lots of experience with 3,000 hrs. total. Sheesh, I wasn't hired at a major until I had 5,000.

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    Quote Originally Posted by EmanuelGoldstein View Post
    SAnd I'm pretty good at sniffing out bullshit. et ...
    Yeah, me too. My uncle once knew a guy, who's cousin dated a pilot that said that 737 maxs were deathtraps.

    Your guy = my guy.

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    Quote Originally Posted by n2zon View Post
    That's the history of transportation in a nutshell. Or machine work, scuba diving, bridge building....
    Granted, but most deaths in those endeavors were not directly related to a software error.

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    Quote Originally Posted by jim rozen View Post
    Granted, but most deaths in those endeavors were not directly related to a software error.
    After a long career in software, I am forced to predict that more of them will be in the future. Software is cheap relative to hardware, and we're putting lots and lots of it into automobiles, aircraft, and spacecraft. We're also using it to design and build bridges, run dive computers, and run machine tools. (Was the "glitch" in that mill that caused the tool to disintegrate a software error? The prevailing wisdom seems to be not, but we do not actually know.)

    Today's software can be mind-bogglingly complicated. It's viciously hard, if not impossible, to create such complex systems that are error-free, and you can't test all the errors out in a reasonably finite amount of time. This is especially true of infrequently-trodden code pathways and error edge cases where multiple errors are involved.

    It's taken millenia for mechanical, architectural, electrical, and civil engineering to reach their current states. Lots of stuff fell down or failed while people learned, and lots of people died while they learned. Software is just not very old, and we're still learning a lot about how to construct it.

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    ???

    NEW YORK (AP) -- Just days after a Lion Air Boeing 737 Max nosedived in Indonesia and killed all 189 people aboard, an Ethiopian Airlines pilot began pleading with his bosses for more training on the Max, warning that crews could easily be overwhelmed in a crisis and that one of their planes could be the next to go down.

    "We are asking for trouble," veteran pilot Bernd Kai von Hoesslin wrote in a December email obtained by The Associated Press, adding that if several alarms go off in the cockpit at once, "it will be a crash for sure."


    Ethiopian pilot pleaded for training weeks before Max crash

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    " Software is just not very old, and we're still learning a lot about how to construct it. "

    Excuse me but that's nonsense. The software in the case simply failed to account for the single
    attack angle sensor and repeatedly pushed the nose down from incorrect sensor data. This
    does not require a quantum computer to figure out what went wrong. A high school kid could
    easily have informed the geniuses at boeing about how to prevent this tragedy.

    The software issue in this case is about as old as airplanes.

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    Quote Originally Posted by jim rozen View Post
    " Software is just not very old, and we're still learning a lot about how to construct it. "

    Excuse me but that's nonsense. The software in the case simply failed to account for the single
    attack angle sensor and repeatedly pushed the nose down from incorrect sensor data. This
    does not require a quantum computer to figure out what went wrong. A high school kid could
    easily have informed the geniuses at boeing about how to prevent this tragedy.

    The software issue in this case is about as old as airplanes.
    It is often easy to point at a failure and think it should never have happened. Finding the bug after the fact isn't the problem. Some failures are simple ("Oh, it should have done *this* and not *that*") and some are far less simple ("You mean that when *that* happens *this other sequence of events* happened, we needed to do something different?"). Some are exposed or even inflicted by seemingly-unrelated changes to the overall system, of which the original programmer was never even aware, or by errors in the specifications for the software and not in the actual coding.

    Correctly imagining every single case that can occur, in advance, fully understanding what code is being reused in some new context, and coding all the choices correctly are the elements of the problem. Like it or not, programmers are human, and they can only hold so much in their heads at a time. We're all fallible.

    It would not surprise me to learn that there are millions of lines of code running in a modern airliner. I have seen statistics for operating system software branches, but I no longer recall them. Let's posit, for a moment, that 5% of instructions area branches (choices). That would make 50,000 branches per 1M lines of code. Each branch is a binary event. A particular path through all 50K branches would have 50K conditions associated with it. Some percentage of those 50K conditions are affected by one or more preceding conditions. This is what makes it hard, and we have not yet figured out how to reliably prevent or correct these failures of imagination.

    These problems are not nearly so old as airplanes. The Rhinebeck Aerodrome is not far from here. None of those airplanes have any software at all. The same can be said of a 1980's-era airliner or Cessna. "Software engineering" is in its infancy yet.

    It's not directly related to the 737's woes, but I'll use software security as another example. How many security fixes come out every month for, say, Windows? Every one of those represents a fix to a software error that survived development and testing and got released to the field. (And if you think your life will never depend on Windows software, you haven't looked at hospital equipment lately.)

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    you're confusing software error with a bad design, the software wasn't bad in this case that it acted based on input from one(?) sensor, the overall design of this particular system was just wrong

    bit of OT, but I've had experience with a fault on my car (BMW) where a faulty engine oil level sensor made the car undrivable, I literally stepped out of a perfectly fine working vehicle, and 5 minutes later I couldn't start it, it turned out that the oil level sensor failed in such a way that it disabled a CAN bus that the engine control unit and gearbox were talking to each other (ABS is on the same CAN bus btw), engine didn't know if the gearbox was in park/neutral and wouldn't allow to activate starter motor - this is a perfect example of an absolutely non-critical sensor causing a "catastrophic" problem just because some engineer didn't think to wire this sensor in one of the other 2 or 3 CAN buses, where steering wheel buttons talk to radio to change volume for example

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    Quote Originally Posted by jz79 View Post
    you're confusing software error with a bad design, the software wasn't bad in this case that it acted based on input from one(?) sensor, the overall design of this particular system was just wrong

    bit of OT, but I've had experience with a fault on my car (BMW) where a faulty engine oil level sensor made the car undrivable, I literally stepped out of a perfectly fine working vehicle, and 5 minutes later I couldn't start it, it turned out that the oil level sensor failed in such a way that it disabled a CAN bus that the engine control unit and gearbox were talking to each other (ABS is on the same CAN bus btw), engine didn't know if the gearbox was in park/neutral and wouldn't allow to activate starter motor - this is a perfect example of an absolutely non-critical sensor causing a "catastrophic" problem just because some engineer didn't think to wire this sensor in one of the other 2 or 3 CAN buses, where steering wheel buttons talk to radio to change volume for example
    Having spent the majority of my career in software design and development, I doubt I am confusing the two things, but they are in any case very difficult to separate, and they are iterative. Development discovery often causes design changes, and design re-scoping often changes development direction or causes rework. There are also often multiple levels of design at various levels of detail, which clouds the issue further.

    From what I understand, the original design parameters were found not to work in flight testing. The control authority of the system was increased as a result. At some point, the possible consequences of these changes were missed in review, and a necessary* software change was not implemented.

    All obvious in hindsight, but a good example of missing an error scenario or other edge case in a complex HW/SW system. If someone can figure out how to detect this sort of thing 100% of the time, they stand to make billions of dollars on the patent. Software error correction is expensive, and the consequences of a software error can of course be far more expensive. The latter is why nearly every software contract declines to indemnify users from consequential damages.

    It all looks as though it should be simple enough. It's just not, once you get past little programs that have very limited scope.

    [Edit] * I should have added that this might have also been fixed in hardware. But I presume Boeing did a cost analysis and determined that the software fix was cheaper, which is quite often the case. And, if it is less expensive to fix in software now, it would have been far less expensive to have fixed it in software originally.

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    Quote Originally Posted by n2zon View Post
    [Edit] * I should have added that this might have also been fixed in hardware. But I presume Boeing did a cost analysis and determined that the software fix was cheaper, which is quite often the case. And, if it is less expensive to fix in software now, it would have been far less expensive to have fixed it in software originally.
    Unfortunately that boat sailed a long time ago. Their cost analysis is all shot to heck and gone. Money, reputation, sales, all blown
    up from that chain of errors.

    I've flown out of the Rhinebeck aerodrome - in their new standard. Great trip. While the notion of software was not around when
    many of those planes were built, the core value of 'keep it in the air' was and is pervasive in those planes. Like the car that
    simply becomes an inert rock because one sensor fails off the buss, the 737 max becomes a brick that falls out of the sky because
    one computer says it needs to.

    The planes at Rhinebeck are the opposite. If the mag wire falls off the mag, the spark keeps coming, the plane stays in the air.
    That's not software engineering but the concept is the same. Figure out what goes wrong and how to keep the plane in the air.

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