More complicated than this, The FAA required the MCAS for certification. W/o MCAS, it was deemed to unstable to be airworthy.

So why could Boeing not design it right in the first place? It is easy for people to just assume they made stupid mistakes, but that is very unlikely to me. I presume they made engineering decisions and tradeoffs based on issues we do not know. And if so, can they implement a system that does not push the risk elsewhere?

Do agree that the true next gen mid-size (whatever it is) is needed ASAP. Even if they fix this issue, the 737 kind of sucks.

It actually is fairly straightforward.

The single-input is a huge engineering mistake - that needs to be corrected. The fix is basically done; just has to be qualified. That'll reduce the rate of occurrence to more acceptable levels.

It's not a matter of "moving the risk elsewhere" - it's a matter of the pilots knowing the proper procedure for responding to a runaway stabilizer. This is a situation that is trained for -- and has been trained for -- for decades. But, because of MCAS, it can occur at a different phase of flight than is usually trained for. But the response is exactly the same -- slap the stab trim cutout switches, and everything is back to normal.

Fast forward to 2:45 to see the proper procedure:
But that's all that has to happen ... and at this point, I'd guaran-freakin-tee that ANY 737 pilot would respond by hitting the stab trim cutouts right away. I'd argue that the 737MAX is plenty safe to fly as it sits; since any pilot will know what to do now.

Thanks for your clear description of techniques and issues in this and other posts.

As a layperson, I'm wondering if there was a typo (in red): would MCAS only be operating when autopilot is on rather than off? The former makes intuitive sense to me, but if it's the latter — I am curious why would MCAS only operate when autopilot is off? From what I have understood so far, the MCAS was added to give the MAX a manoeuvring feel consistent with the non-MAX, but if it's primarily intended as a manual pilot aid, I don't understand why disconnecting the autopilot is part of the corrective action.

I think this question is complementary to zdog2x's post just above; it seems like an odd pattern that both of the problem flights crashed soon after takeoff.

———

Also, NPR's All Things Considered did a pretty nice summary of the market pressures (fuel) and design constraints (frame dimensions vs. engine size) that led to the conception of MCAS.

Link to summary:
https://www.npr.org/2019/03/22/70597...s-737-max-jets

Link to audio:
https://ondemand.npr.org/anon.npr-mp...7_max_jets.mp3

(This isn't UA specific, but I'm posting here for continuity of discussion.)

Garuda had deferred almost their entire order well before the first crash. They are in a extreme financial pinch.

I read somewhere (I don't recall where and I am sure someone will correct me if I am wrong) that this could be one of the phases of flight where MCAS is most important.

Because of the higher / farther forward mounting of the MAX's engines and their location relative to the center of gravity compared to non-MAX 737s, a nose-high attitude like that experienced during initial climb makes the engines themselves in effect lift devices (as the oncoming air pushes up at the bottoms of the engines), leading to an even more nose-high attitude and a more critical AoA that may not be responded to adequately enough by the pilots. Boeing determined during flight testing that the MCAS solution was necessary to counteract that effect.

It says airline employees asked victims' families to waive suing the airline.

I don't see where it says Boeing employees asked that they waive the right to go after Boeing.

you are 110% right, my bad. The paragraph talks about Boeing's liability and I just read it wrong... will remove from my post so as not to confuse anyone. Gott'a admit when you got it wrong. ;)

Ya, pretty good.

And it is radio, but hopefully NPR would not show picture of front of 737 from two generations ago that still shows the "eyebrow" windows (that were used to navigate by stars IIRC) like ABC news showed for the SECOND night in a row in their video :rolleyes:

Pretty sure no one ever navigated 737 Classics by the stars.

That's because the moonroof option is too expensive for the airlines.

Your facts don't counter my facts. And my facts deal with human beings.

Too many people around here in love with machines and companies, finding all sorts of ways to apologize for them. Not so much with actual people.

Even more complicated, Boeing in their filings w/ the FAA reported that MCAS would be able to make a maximum adjustment of 0.6 degrees. However when they realized that would not be enough to compensate for the stall-risk, they adjusted MCAS to be able to make 2.5 degrees of adjustment. Except they neglected to mention that change to the FAA, so the final FAA analysis/approval was done using incorrect numbers.

The only place where we disagree is that I do think Boeing and/or the regulators have an interest in operating an aircraft even with faults, as long as they can rationalize the faults to minor or not dangerous or hazardous to people's lives. "What can possibly go wrong?" We've seen, twice in five months, what can possibly go wrong.

I want my manufacturers and regulators to be absolutely ruthless about safety, and in this case, I think the foot went ever so slightly off the gas.

Absolutely, the MAXes will be safer when they return to service. They damn well ought to be. And it shouldn't have taken stalling on the part of Boeing to ground 'em on the second crash, let alone the first. Abundance. of. caution. Not abundance of profits.