6 ms·

Why isn't it enough to retrofit all past and future models with enough hardware redundancy and create a properly written MCAS software? Wasn't the design sound

by devit 7y ago

Why isn't it enough to retrofit all past and future models with enough hardware redundancy and create a properly written MCAS software? Wasn't the design sound, except for the lack of hardware sensor redundancy and naively written software? Why do they need to stop production and so on?

cooljacob204 7y ago
Because 300+ people died.
gpm 7y ago
> Wasn't the design sound, except for the lack of hardware sensor redundancy and naively written software? How would you possibly know that? If they missed two serious issues what makes you think they didn't miss more? Err, make that three serious issues: https://www.cnn.com/2019/06/26/politics/boeing-737-max-flaw/index.html https://www.cnn.com/2019/06/26/politics/boeing-737-max-flaw/... Edit: 4 serious issues if you count "identifying problems and not fixing them": https://www.cnn.com/2019/05/05/us/boeing-737-max-disagree-alert/index.html https://www.cnn.com/2019/05/05/us/boeing-737-max-disagree-al...
pastor_elm 7y ago
>"Wasn't the design sound" What's so sound about a plane that stalls by default?
- gpm 7y ago
  Flip that around, what's unsound with such a design? There are lots of things on planes where "if you don't do this" then "the plane crashes and burns". Having to adjust horizontal stabilizer trim as you gain speed is a minor addition. MCAS was problematic because of how it went about doing so, and how pilots weren't properly trained on the change in how the trim needs to be adjusted. The idea of adjusting the trim doesn't seem fundamentally flawed to me. (Not that I think the design is necessarily sound, see my direct reply to gp for why).
  - stetrain 7y ago
    That's all fine provided the pilots are properly trained. The fundamental sales proposition of the 737 MAX was that your pilots would not need additional training. If the end result is that a new type certification is required for the 737 MAX, it may still be a viable product but not the one customers were originally sold on.
samcheng 7y ago
My understanding is that the design is fundamentally flawed; the engines are too large to fit under the wings with the existing landing gear, so they were moved forward, thereby upsetting the balance between the center of thrust of the engines and the center of lift of the wings, thereby requiring a brittle MCAS system to attempt to compensate. The MCAS system itself is flawed in a number of ways, but the core problem (in my opinion) is the attempt to fit large engines under a too-small airplane, in the name of saving regulatory / training costs.
- armada651 7y ago
  Actually it's important to remember that MCAS was not fitted to make the plane safer. It was fited to make it behave the same way as a 737 so that pilots don't need to be retrained. If you would retrain pilots then the 737 MAX can be safely flown without MCAS. Pilots just need to be familiar with the different aerodynamics.
  - ahakki 7y ago
    A 737 Max without MCAS doesn't have linearly increasing stick forces as AOA increases. This is a FAA requirement, so the 737 MAX can't be approved without the MCAS system, regardless if it could be flown by a trained pilot.
tjpnz 7y ago
Even if they somehow managed to make the MAX safe no person in their right mind's going to want to get onboard it. Muilenburg certainly didn't help the situation either with all his talk of pilot error at the beginning.
CydeWeys 7y ago
Because these changes are going to require a new type certification, which defeats the entire point of just making a better 737 in the first place. It will no longer be nearly as appealing to airlines. They might actually be better off just axing the MAX entirely and continuing to produce the 737 NG, and then work on a clean sheet 737 replacement that doesn't suffer from all the compromises inherent in the MAX.
- mikepurvis 7y ago
  What does that mean for all the Max units currently out there and grounded, though? Obviously there's going to be a huge and drawn-out lawsuit over this, but it seems like at the end of the day, the airlines involved will still end up having to train their pilots on those planes in order to get them back in the air, and at that point, they might as well have a bunch more of them anyway. And if they're doing the new-plane certification and training anyway, the MCAS no longer has any point and could perhaps just be turned off? Edit: Perhaps not— this comment asserts that the handling of the airframe sans MCAS is non-compliant with FAA requirements: https://news.ycombinator.com/item?id=21864584 https://news.ycombinator.com/item?id=21864584
  - tw04 7y ago
    I would assume a buyback as part of the write-down. I'm not sure any airline wants to be one of the handful of "lucky" ones that have the only MAX's in the air. Sounds like a great way to lose customers.
    - mikepurvis 7y ago
      What a nightmare. Will the 387 delivered planes* be retrofitted somehow, or are they really just scrap at this point? Is there precedent for a recall of this magnitude in commercial aerospace? * https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders_and_deliveries https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders_...
      - CydeWeys 7y ago
discretelious 7y ago
The issue is not that this plane kills people— although it is shocking that this plane does kill people. The issue is that a culture of self-interested mismanagement from factory floors up to our highest political offices has led the global economy to depend on the success of this plane which kills people. Even if somehow by chance they manage to make this plane kill fewer people in the future, there will be no reason to think the actual problem has been addressed.
- rightbyte 7y ago
  Does the global economy really need passenger planes? Tourism economies, sure, but I would guess most of the economy is dependent on trains, trucks and ships?
  - Jamwinner 7y ago
    Yes, meetings still happen face to face for business to get done. Giving up air travel, is not a reasonable option for the world at large.
    - temac 7y ago
      Giving up things like modern medicine would not be reasonable. Giving up air travel, or at least reducing it vastly, would be merely an inconvenience. Well yeah, giving up air travel entirely would be somehow a mess, but even there it is completely sure we can make it work. In France the train is ~50 x more carbon efficient. We will not be able to keep emitting like crazy forever (we actually should have stopped completely already :/ ) , especially when reasonable alternatives exist (the train if going not too far, teleconferences, ...). If we believe in the markets, the price of an air ticket should be maybe 50x higher than what it is today, in order to stop the insane emissions. Alternatively there could be an authority who decide if we have a good reason to take the plane.
      - ferzul 7y ago
        If trains are so much better, why is it cheaper to fly?
petilon 7y ago
If that was all that's needed 737 Max's would all be back in the air by now. There is a fundamental problem in the design. The plane tends to pitch up when accelerating. Under certain circumstances this can cause the plane to stall and fall out of the sky. This was fixed using software. Most planes have airframes that are aerodynamically stable in and of itself. The 737 Max requires software assistance to be at the same level of stability. That, to me, is a fundamental flaw. In a multilayer system each layer needs to be safe in and of itself. The purpose of higher layers is to add functionality not to fix flaws in lower layers. Given the fundamental flaws in design it was obvious there was a cultural problem at Boeing and the CEO needed to go. "We can't solve problems by using the same kind of thinking we used when we created them." -- Einstein.
- lujim 7y ago
  I agree with you, but would like one counterpoint. There are plenty of planes that are aerodynamically unstable and require fly by wire/computers for satisfactory flight characteristics. Fighters like relaxed aerodynamic roll stability for roll rate. Now pitch stability issues are troubling. I don't think engineers would purposely relax pitch stability unless they had to. I guess I'm saying you might want an airplane aerodynamically unstable in roll, but pretty much never in pitch so the fly by wire argument might not be valid here.
  - jamiek88 7y ago
    >There are plenty of planes that are aerodynamically unstable and require fly by wire/computers for satisfactory flight characteristics. Not passenger aircraft. Only military.
- na85 7y ago
  >The plane tends to pitch up when accelerating. They all do this. You have giant engines on the underside of the wing; what else would you expect to happen when you throttle up at low airspeed?
  - petilon 7y ago
taneq 7y ago
The problem with Boeing isn’t MCAS. The problem is that the company was capable of shipping such a flawed design and then pretending it was OK even in the face of hundreds of deaths. How could you ever trust the output of such a company, especially with your life? Just firing the CEO isn’t enough, they need to root out everyone complicit in this crime.
_ph_ 7y ago
Yes, fixing the MCAS software should solve the problem of the 737 MAX. But with all what happened, authorities are extra thorough before allowing the 737 MAX to fly again. Probably all what is needed is a few more months of patience. On the grand scale of things, the bigger issues with Boeing are how they do business and all the problems with their facturies that have surfaced recently. Beyond getting the 737 MAX to flight status, they have to resolve all the issues and the management problems which lead to them.
- ben509 7y ago
  > But with all what happened, authorities are extra thorough before allowing the 737 MAX to fly again. I think this is entirely true, but it's an interesting commentary on the structure of regulation: it's some small part technical investigation, and a much larger part public relations. I can't even argue they're wrong to operate that way, since their mission is to build public trust in air travel, but it produces absurd results in other areas, e.g. airport security theater.
- dubliner2077 7y ago
  Unlikely you can fix that when even the processor gets overloaded by patches.
stetrain 7y ago
The fundamental promise made to customers (a more efficient 737 that doesn't require new pilot training) seems impossible to deliver at this point, and probably wasn't possible from the outset. At this point they could probably still turn the 737 Max into a sellable product, but it will be different from the one promised if it requires a new type certification for pilots due to the different flight characteristics (which Boeing was trying to hide/minimize with MCAS).
fossuser 7y ago
I’d guess lack of trust at this point - they lied and denied responsibility for a while when the crashes happened. They seem to have some serious cultural issues, I wouldn’t trust them to do the job correctly. I’d suspect in the end what your suggesting is probably what’ll happen.

by devit 7y ago

cooljacob204 7y ago

Because 300+ people died.

gpm 7y ago

> Wasn't the design sound, except for the lack of hardware sensor redundancy and naively written software? How would you possibly know that? If they missed two serious issues what makes you think they didn't miss more? Err, make that three serious issues: https://www.cnn.com/2019/06/26/politics/boeing-737-max-flaw/index.html https://www.cnn.com/2019/06/26/politics/boeing-737-max-flaw/... Edit: 4 serious issues if you count "identifying problems and not fixing them": https://www.cnn.com/2019/05/05/us/boeing-737-max-disagree-alert/index.html https://www.cnn.com/2019/05/05/us/boeing-737-max-disagree-al...

pastor_elm 7y ago

>"Wasn't the design sound" What's so sound about a plane that stalls by default?

gpm 7y ago
Flip that around, what's unsound with such a design? There are lots of things on planes where "if you don't do this" then "the plane crashes and burns". Having to adjust horizontal stabilizer trim as you gain speed is a minor addition. MCAS was problematic because of how it went about doing so, and how pilots weren't properly trained on the change in how the trim needs to be adjusted. The idea of adjusting the trim doesn't seem fundamentally flawed to me. (Not that I think the design is necessarily sound, see my direct reply to gp for why).
- stetrain 7y ago
  That's all fine provided the pilots are properly trained. The fundamental sales proposition of the 737 MAX was that your pilots would not need additional training. If the end result is that a new type certification is required for the 737 MAX, it may still be a viable product but not the one customers were originally sold on.

samcheng 7y ago

My understanding is that the design is fundamentally flawed; the engines are too large to fit under the wings with the existing landing gear, so they were moved forward, thereby upsetting the balance between the center of thrust of the engines and the center of lift of the wings, thereby requiring a brittle MCAS system to attempt to compensate. The MCAS system itself is flawed in a number of ways, but the core problem (in my opinion) is the attempt to fit large engines under a too-small airplane, in the name of saving regulatory / training costs.

armada651 7y ago
Actually it's important to remember that MCAS was not fitted to make the plane safer. It was fited to make it behave the same way as a 737 so that pilots don't need to be retrained. If you would retrain pilots then the 737 MAX can be safely flown without MCAS. Pilots just need to be familiar with the different aerodynamics.
- ahakki 7y ago
  A 737 Max without MCAS doesn't have linearly increasing stick forces as AOA increases. This is a FAA requirement, so the 737 MAX can't be approved without the MCAS system, regardless if it could be flown by a trained pilot.

tjpnz 7y ago

Even if they somehow managed to make the MAX safe no person in their right mind's going to want to get onboard it. Muilenburg certainly didn't help the situation either with all his talk of pilot error at the beginning.

CydeWeys 7y ago

Because these changes are going to require a new type certification, which defeats the entire point of just making a better 737 in the first place. It will no longer be nearly as appealing to airlines. They might actually be better off just axing the MAX entirely and continuing to produce the 737 NG, and then work on a clean sheet 737 replacement that doesn't suffer from all the compromises inherent in the MAX.

mikepurvis 7y ago
What does that mean for all the Max units currently out there and grounded, though? Obviously there's going to be a huge and drawn-out lawsuit over this, but it seems like at the end of the day, the airlines involved will still end up having to train their pilots on those planes in order to get them back in the air, and at that point, they might as well have a bunch more of them anyway. And if they're doing the new-plane certification and training anyway, the MCAS no longer has any point and could perhaps just be turned off? Edit: Perhaps not— this comment asserts that the handling of the airframe sans MCAS is non-compliant with FAA requirements: https://news.ycombinator.com/item?id=21864584 https://news.ycombinator.com/item?id=21864584
- tw04 7y ago
  I would assume a buyback as part of the write-down. I'm not sure any airline wants to be one of the handful of "lucky" ones that have the only MAX's in the air. Sounds like a great way to lose customers.
  - mikepurvis 7y ago
    What a nightmare. Will the 387 delivered planes* be retrofitted somehow, or are they really just scrap at this point? Is there precedent for a recall of this magnitude in commercial aerospace? * https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders_and_deliveries https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders_...
    - CydeWeys 7y ago

discretelious 7y ago

The issue is not that this plane kills people— although it is shocking that this plane does kill people. The issue is that a culture of self-interested mismanagement from factory floors up to our highest political offices has led the global economy to depend on the success of this plane which kills people. Even if somehow by chance they manage to make this plane kill fewer people in the future, there will be no reason to think the actual problem has been addressed.

rightbyte 7y ago
Does the global economy really need passenger planes? Tourism economies, sure, but I would guess most of the economy is dependent on trains, trucks and ships?
- Jamwinner 7y ago
  Yes, meetings still happen face to face for business to get done. Giving up air travel, is not a reasonable option for the world at large.
  - temac 7y ago
    Giving up things like modern medicine would not be reasonable. Giving up air travel, or at least reducing it vastly, would be merely an inconvenience. Well yeah, giving up air travel entirely would be somehow a mess, but even there it is completely sure we can make it work. In France the train is ~50 x more carbon efficient. We will not be able to keep emitting like crazy forever (we actually should have stopped completely already :/ ) , especially when reasonable alternatives exist (the train if going not too far, teleconferences, ...). If we believe in the markets, the price of an air ticket should be maybe 50x higher than what it is today, in order to stop the insane emissions. Alternatively there could be an authority who decide if we have a good reason to take the plane.
    - ferzul 7y ago
      If trains are so much better, why is it cheaper to fly?

petilon 7y ago

If that was all that's needed 737 Max's would all be back in the air by now. There is a fundamental problem in the design. The plane tends to pitch up when accelerating. Under certain circumstances this can cause the plane to stall and fall out of the sky. This was fixed using software. Most planes have airframes that are aerodynamically stable in and of itself. The 737 Max requires software assistance to be at the same level of stability. That, to me, is a fundamental flaw. In a multilayer system each layer needs to be safe in and of itself. The purpose of higher layers is to add functionality not to fix flaws in lower layers. Given the fundamental flaws in design it was obvious there was a cultural problem at Boeing and the CEO needed to go. "We can't solve problems by using the same kind of thinking we used when we created them." -- Einstein.

lujim 7y ago
I agree with you, but would like one counterpoint. There are plenty of planes that are aerodynamically unstable and require fly by wire/computers for satisfactory flight characteristics. Fighters like relaxed aerodynamic roll stability for roll rate. Now pitch stability issues are troubling. I don't think engineers would purposely relax pitch stability unless they had to. I guess I'm saying you might want an airplane aerodynamically unstable in roll, but pretty much never in pitch so the fly by wire argument might not be valid here.
- jamiek88 7y ago
  >There are plenty of planes that are aerodynamically unstable and require fly by wire/computers for satisfactory flight characteristics. Not passenger aircraft. Only military.
na85 7y ago
>The plane tends to pitch up when accelerating. They all do this. You have giant engines on the underside of the wing; what else would you expect to happen when you throttle up at low airspeed?
- petilon 7y ago

taneq 7y ago

The problem with Boeing isn’t MCAS. The problem is that the company was capable of shipping such a flawed design and then pretending it was OK even in the face of hundreds of deaths. How could you ever trust the output of such a company, especially with your life? Just firing the CEO isn’t enough, they need to root out everyone complicit in this crime.

_ph_ 7y ago

Yes, fixing the MCAS software should solve the problem of the 737 MAX. But with all what happened, authorities are extra thorough before allowing the 737 MAX to fly again. Probably all what is needed is a few more months of patience. On the grand scale of things, the bigger issues with Boeing are how they do business and all the problems with their facturies that have surfaced recently. Beyond getting the 737 MAX to flight status, they have to resolve all the issues and the management problems which lead to them.

ben509 7y ago
> But with all what happened, authorities are extra thorough before allowing the 737 MAX to fly again. I think this is entirely true, but it's an interesting commentary on the structure of regulation: it's some small part technical investigation, and a much larger part public relations. I can't even argue they're wrong to operate that way, since their mission is to build public trust in air travel, but it produces absurd results in other areas, e.g. airport security theater.
dubliner2077 7y ago
Unlikely you can fix that when even the processor gets overloaded by patches.

stetrain 7y ago

The fundamental promise made to customers (a more efficient 737 that doesn't require new pilot training) seems impossible to deliver at this point, and probably wasn't possible from the outset. At this point they could probably still turn the 737 Max into a sellable product, but it will be different from the one promised if it requires a new type certification for pilots due to the different flight characteristics (which Boeing was trying to hide/minimize with MCAS).

fossuser 7y ago

I’d guess lack of trust at this point - they lied and denied responsibility for a while when the crashes happened. They seem to have some serious cultural issues, I wouldn’t trust them to do the job correctly. I’d suspect in the end what your suggesting is probably what’ll happen.