There’s a bigger difference between the MAX family and other versions of the 737 than there is between all the different crossovers a car company pumps out.
Boeing 737 MAX 7 is 138,699 lbs vs 737 800 @ 90,710lb vs 737 100 @ 61.994 lbs. Hell the new 737 MAX 10 is ~203,000 lb.
Is the size the biggest difference or the fact that the center of gravity is totally different? So much so, they created an "hidden" software program to counter the CoG difference so the pilots feel like it is in the same place they are used to?
The problem with the Max is aerodynamics: Civil airplanes are designed with negative aerodynamic feedback, so the nose-down torque (“pitching moment”) increases as the AoA increases. But on the Max at very high AoA this feedback torque becomes somewhat smaller due to interaction of airflow around the engines and the wing. That by itself is not a problem because the nose-down torque still exists and airframe is still stable.
There is a regulatory requirement that the amount of pilot’s control force required to maintain a given AoA must be a non-decreasing function of AoA[1]. Due to the Max’s aerodynamics, this requirement is not met.
Boeing’s MCAS was a bandaid to make the plane meet regulations by applying nose-down trim while at high AoA. The trim results in a higher yoke force, so the plane meets the requirement. A better method would have been a “stick pusher” (which have been used as stall prevention devices for over 50 years, though not on the 737) or addition ventral fins (like on the Beech 1900). But either of those would have probably required recertification
[1] The purpose of this is to reduce pilot-induced oscillations: see what happened with AA flight 587, where the lack of a similar requirement for rudder pedals and yaw led to PIO which ultimately resulted in the tail falling off an Airbus.
Regardless of how one characterizes the magnitude of the changes, if the unanticipated difficulties had been handled openly, there would be no question of criminal liability. Furthermore (though it is also beside the point), physics has not ruled out the MAXes.
In addition, the door-plug issue is tied in here on account of the 2021 deferred prosecution agreement, which also followed from Boeing's duplicity over the MAX issue.
> Regardless of how one characterizes the magnitude of the changes, if the unanticipated difficulties had been handled openly, there would be no question of criminal liability
You’re skipping over the first half of my statement. If the unexpected difficulties had been handled openly they would have needed to go through more regulatory hurdles. Physics didn’t put them into some kind of catch 22 situation the aircraft could have been safe, it just couldn’t be safe while playing games with regulators. That’s where criminal liability shows up.
As far as I can tell, I'm just skipping over the issues which may be true, but are beside the point, but then, it is not clear to me which statement's first half you think I am skipping over.
The point I have been making all along is that, regardless of what led Boeing to the point of choosing to hide or misrepresent the situation, it is the choice to do so that turns this into a potentially criminal matter. With the same physical/technical problems but proper and timely disclosure of the issues during development, by far the most likely outcome would have been a delayed program delivering MAXes substantially similar (in both construction and operation) to the ones which are certified and flying today. After that, even in the unlikely event that the crashes had occurred, criminal prosecution would be unlikely, and certainly not on the basis of the facts for which it is currently being considered.
> substantially similar (in both construction and operation)
The physical aircraft would have been similar, but airlines would have spent 10’s of millions more on training which makes a real difference to them and thus sales.
Boeing could have released the aircraft on exactly the same date while complying with the spirit of relevant relations though at higher costs, but the product would have been meaningfully worse from a sales perspective. Even today regulators have allowed Boeing and the airlines to treat the 737 MAX family as much more closely related to earlier 737’s than they actually are.
All of these things are beside the point here because none of them form the basis on which criminal proceedings are being considered by the DOJ. Without the information hiding and misrepresentation, there is no basis, regardless of either the physics or the economics of the issue.
In addition, even if it is true that regulators have now allowed Boeing and the airlines to treat the 737 MAX family as much more closely related to earlier 737’s than they actually are, this is not the basis of the DOJ's investigation, either.
The motives were there regardless of how Boeing chose to act. It's the chosen act that is potentially criminal. The DOJ is not in any doubt as to whether or not Boeing had a motive, and it is not considering at all the question of whether regulators have now allowed Boeing and the airlines to treat the 737 MAX family as much more closely related to earlier 737’s than they actually are, regardless of any parties' motives in that regard.
It is not at all clear what (if anything) A and B are standing in for here, so instead of discussing them, let's go back and see what specific issue prompted our disagreement over whether it was to the point here. It was just this: "There’s a bigger difference between the MAX family and other versions of the 737 than there is between all the different crossovers a car company pumps out..." [1] (specific weight differences elided for brevity.)
I won't dispute the implicit claim that this was an important factor in Boeing running into development difficulties, but running into development difficulties is not a crime. Materially misrepresenting the state of the development process (specifically (IMHO) the magnitude of the high-AofA handling problem, rather than merely weight issues) to the FAA is a crime, and it is this, not the fact that Boeing ran into technical difficulties, that is the point of DOJ's investigation, the article, and the discussion here of it.
It wasn’t developed difficulties at issue here. They inserted a system and hid what it did and where it could fail from pilots and airlines. Quite literally removing it from the manual: “elected to not describe it in the flight manual or in training materials” https://en.wikipedia.org/wiki/Maneuvering_Characteristics_Au...
So when it failed and pilots had no idea what the issue was people died. The crazy thing here is telling pilots about it could have prevented those crashes even with an absolutely identical aircraft being released.
Perhaps the first thing to note about your latest response is that it makes no mention of the increase of weight of the MAXes over their predecessors, and yet it was specifically over the relevance of the weight change where we disagreed [1]. I have followed this story quite closely, and I haven't seen anyone citing the weight gain as being a factor in this tragedy, let alone claiming that the weight gain itself amounted to something criminal (or that Boeing was somehow hiding it, for that matter), and your summary here, by its omission of the weight issue, tacitly acknowledges its lack of relevance.
The second omission from this summary is any mention of Boeing's interaction with the FAA staff having the responsibility for certifying the MAXes as airworthy (together with the adequacy of the flight manuals and training materials), and yet, in all other accounts I have seen, Boeing misrepresented (to put it mildly) the extent to which MCAS was modifying the handling characteristics of the airplane and therefore the consequences of its failure and the need for pilots to know about it. No-one else, as far as I am aware, disputes the fact that the DOJ's investigation is centered on this dissembling (together with similar dissembling relating to the plug door incident, which is being included on account of the MAX issue being in a deferred prosecution status.) Once your account here is augmented with this missing information, it becomes clear that this pattern of dissembling is what the DOJ is investigating as a possible crime, as I have been saying all along.
Now you want to extend this disagreement by disputing my characterization of Boeing's difficulties in developing the MAXes as being, well, development difficulties! It is not clear to me what point you are trying to make by doing so, but to be clear, I am most certainly not dismissing the tragedy as merely a matter of development difficulties. On the contrary, I am saying that this became a criminal matter precisely when Boeing went beyond treating the matter as an above-the-board technical problem, and started misleading the FAA.
Boeing 737 MAX 7 is 138,699 lbs vs 737 800 @ 90,710lb vs 737 100 @ 61.994 lbs. Hell the new 737 MAX 10 is ~203,000 lb.