4 ms·

This it's how I read it: 1. Boeing is not blameless. 2. Boeing has a point about MCAS issues manifesting exactly like another well-known event in other models

This it's how I read it: 1. Boeing is not blameless. 2. Boeing has a point about MCAS issues manifesting exactly like another well-known event in other models and having the exact same solution. 3. The well-known solution to the well-known event is one that pilots must memorize because they don't have time to look it up. 4. The pilots seem to have demonstrated that they recognized the problem and, in fact, executed the well-known solution in time. They just failed to complete all the steps for some unknown reason. 5. Points 2-4 don't mean that Boeing is perfect. MCAS needs to be fixed. But it isn't completely absurd to argue that MCAS really is so similar in its misbehavior and so identical in the correct response that a reasonable person might expect pilots to do the right thing even if they had never heard of MCAS. Taken together, this paints a picture to me that is different than the completely evil, conniving picture I had. I'm not sure where to draw the line between them, but probably not on the extreme end where I had it. But my point is not so much about Boeing. I was observing the actions of a person who took what I expect to be a very unpopular stand in the face of overwhelming popular opinion. For what? Who cares if somebody else is mischaracterized? There's nothing you can do about it except get yourself muddy. Just let it happen and keep your head down. I don't know why Walter is speaking up now. I'm not sure how much it changes my opinion. But I still tip my hat to a person who will say what they think is right even when they know they will be burned at the stake for it.

lisper 7y ago
Thanks for the response. Two follow-up questions: > MCAS issues manifesting exactly like another well-known event in other models and having the exact same solution By "another well-known event" do you mean a runaway trim? Because if you do, then you're mistaken. MCAS and runaway trim differ in significant ways. And if you don't, what do you mean? > I don't know why Walter is speaking up now. Have you considered the possibility that he's a shill?
- jacobush 7y ago
  It sounds so crude... I prefer “biased”. It’s our Walt...
- WalterBright 7y ago
  > Have you considered the possibility that he's a shill? A fair question. I left Boeing's employ (as a flight controls engineer) in 1982. I am not a spokesman for Boeing, paid or otherwise. The facts I've presented here are all public information (though routinely omitted from sensationalist articles about it). My interpretation of those facts is mine alone. We'll see what the final NTSB report says. They have earned a reputation for going where ever the facts lead them, regardless of political pressure. I sincerely hope they continue with this tradition, as it is the only way to make airline travel safe. This highly political case will surely test the NTSB's commitment to dispassionate examination of the facts. We shall see.
  - lisper 7y ago
    > I am not a spokesman for Boeing, paid or otherwise. Isn't that exactly what an effective shill would say? It could even be true. "Shill" and "spokesman" are not synonyms. FWIW, I went back and re-read some of your comments in other branches of this thread and it's really hard for me to figure out what your position actually is. For example: > It's true that if the MCAS software requirements weren't inadequate, the accidents would not have happened. Apart from being a nearly-impossible-to-parse triple negative, it's just absurd on its face. No requirements can ever prevent an accident. I can write down as a requirement: "MCAS software must never cause the plane to crash." But obviously the planes did not crash because someone failed to write down that requirement. If you're really a flight controls engineer then you obviously meant something else. But have no idea what that something else could possibly be. > But I don't see why the shortcomings in the MCAS software design requirements were the result of cost savings. Again, it is hard for me to wring any plausible interpretation out of this sentence under the assumption that you are well informed. It is well known that the reason MCAS exists at all is because Boeing attempted to make a radical change to an existing airframe design without getting it re-certitifed, and the reason for doing that was cost savings, both for Boeing and its customers. What other underlying reason could there possibly be for MCAS to exist at all? > I did not defend Boeing's MCAS design. OK, but do you see how someone could come away with that impression?
    - WalterBright 7y ago
pdonis 7y ago
> Boeing has a point about MCAS issues manifesting exactly like another well-known event in other models and having the exact same solution. No, they don't, because (a) the MCAS issue does not manifest exactly the same as another well-known event (runaway trim), and (b) the solution to the MCAS issue is not the same as the solution to runaway trim. Re (a), normal runaway trim on a 737 manifests as a continuous automatic adjustment of trim. The trim starts moving and doesn't stop until the pilot disables the automatic trim system entirely. The MCAS issue, however, manifests as an intermittent automatic adjustment of trim, at times that seem completely random to the pilot. It is not at all the same as normal runaway trim. Re (b), the procedure for normal runaway trim on previous 737s is to shut off the automatic trim system. You can then use the manual electric trim system to put the trim back where it belongs. The critical fact here is that shutting off the automatic trim system does not shut off the manual electric trim system. But on the 737 MAX, shutting off the automatic trim system, which is what you need to do to disable MCAS, also shuts off the manual electric trim system. So now the only way to get the trim back where it is supposed to be is to use the mechanical trim wheel; and MCAS has enough control authority to put the trim in a place where it is impossible for the pilot to exert enough mechanical force on the trim wheel to move the trim back to where it belongs. So the normal runaway trim response procedure does not work for an MCAS failure. There is a way to recover from an MCAS failure, which is to wait until you are in between intermittent MCAS adjustments of the trim, use the manual electric trim system to put the trim where it is supposed to be, and then shut off the automatic trim system (which, as noted, also disables the manual electric trim system in the 737 MAX). Then you have MCAS disabled and you have the trim in a place where you can use the mechanical trim wheel if needed. But that procedure is not the standard procedure that 737 pilots are trained to do.
deleted 7y ago
[deleted]

lisper 7y ago

Thanks for the response. Two follow-up questions: > MCAS issues manifesting exactly like another well-known event in other models and having the exact same solution By "another well-known event" do you mean a runaway trim? Because if you do, then you're mistaken. MCAS and runaway trim differ in significant ways. And if you don't, what do you mean? > I don't know why Walter is speaking up now. Have you considered the possibility that he's a shill?

jacobush 7y ago
It sounds so crude... I prefer “biased”. It’s our Walt...
WalterBright 7y ago
> Have you considered the possibility that he's a shill? A fair question. I left Boeing's employ (as a flight controls engineer) in 1982. I am not a spokesman for Boeing, paid or otherwise. The facts I've presented here are all public information (though routinely omitted from sensationalist articles about it). My interpretation of those facts is mine alone. We'll see what the final NTSB report says. They have earned a reputation for going where ever the facts lead them, regardless of political pressure. I sincerely hope they continue with this tradition, as it is the only way to make airline travel safe. This highly political case will surely test the NTSB's commitment to dispassionate examination of the facts. We shall see.
- lisper 7y ago
  > I am not a spokesman for Boeing, paid or otherwise. Isn't that exactly what an effective shill would say? It could even be true. "Shill" and "spokesman" are not synonyms. FWIW, I went back and re-read some of your comments in other branches of this thread and it's really hard for me to figure out what your position actually is. For example: > It's true that if the MCAS software requirements weren't inadequate, the accidents would not have happened. Apart from being a nearly-impossible-to-parse triple negative, it's just absurd on its face. No requirements can ever prevent an accident. I can write down as a requirement: "MCAS software must never cause the plane to crash." But obviously the planes did not crash because someone failed to write down that requirement. If you're really a flight controls engineer then you obviously meant something else. But have no idea what that something else could possibly be. > But I don't see why the shortcomings in the MCAS software design requirements were the result of cost savings. Again, it is hard for me to wring any plausible interpretation out of this sentence under the assumption that you are well informed. It is well known that the reason MCAS exists at all is because Boeing attempted to make a radical change to an existing airframe design without getting it re-certitifed, and the reason for doing that was cost savings, both for Boeing and its customers. What other underlying reason could there possibly be for MCAS to exist at all? > I did not defend Boeing's MCAS design. OK, but do you see how someone could come away with that impression?
  - WalterBright 7y ago

pdonis 7y ago

> Boeing has a point about MCAS issues manifesting exactly like another well-known event in other models and having the exact same solution. No, they don't, because (a) the MCAS issue does not manifest exactly the same as another well-known event (runaway trim), and (b) the solution to the MCAS issue is not the same as the solution to runaway trim. Re (a), normal runaway trim on a 737 manifests as a continuous automatic adjustment of trim. The trim starts moving and doesn't stop until the pilot disables the automatic trim system entirely. The MCAS issue, however, manifests as an intermittent automatic adjustment of trim, at times that seem completely random to the pilot. It is not at all the same as normal runaway trim. Re (b), the procedure for normal runaway trim on previous 737s is to shut off the automatic trim system. You can then use the manual electric trim system to put the trim back where it belongs. The critical fact here is that shutting off the automatic trim system does not shut off the manual electric trim system. But on the 737 MAX, shutting off the automatic trim system, which is what you need to do to disable MCAS, also shuts off the manual electric trim system. So now the only way to get the trim back where it is supposed to be is to use the mechanical trim wheel; and MCAS has enough control authority to put the trim in a place where it is impossible for the pilot to exert enough mechanical force on the trim wheel to move the trim back to where it belongs. So the normal runaway trim response procedure does not work for an MCAS failure. There is a way to recover from an MCAS failure, which is to wait until you are in between intermittent MCAS adjustments of the trim, use the manual electric trim system to put the trim where it is supposed to be, and then shut off the automatic trim system (which, as noted, also disables the manual electric trim system in the 737 MAX). Then you have MCAS disabled and you have the trim in a place where you can use the mechanical trim wheel if needed. But that procedure is not the standard procedure that 737 pilots are trained to do.

deleted 7y ago

[deleted]