Only thing Icarus it was not the crew that saved that flight (from the reports).

There seems very little info on this previous Lion Air flight and I/we do not know when the incorrect MCAS input was given. We do know on the two crash flights it was soon after take off, and either after flaps 0 selected or the flaps had fully retracted.

From memory a number of pilots have done the Lion Air & Ethiopian events in the MAX simulator (knowing they will have a MCAS simulation) and they did manage to land safely but said it was "very challenging" - so in a surprise event, the numbers of successful outcomes will reduce. I would have very little doubt the pilots used to do these simulator events, post crashes were nothing but extremely capable pilots selected by Boeing. So in reality it should not have been a challenge at all as many have mentioned, but a breeze or a non event - or did Boeing use substandard pilots for this simulation?

MCAS absolutely should unwind the nose down trim once the AOA drops below 10 degrees (as long as no pilot trim input occurs). I don't have the detailed reference, but this was the whole point of MCAS. It would operate silently in the background, provide a simulated yoke force feedback (or longitudinal stability), and then disengage once the maneuver is completed.

Any automated (and previously undocumented) system that left an aircraft out of trim after a "simple" maneuver, could never possibly be certified. Stall escape implementated by the pilots is an entirely different matter, as was the runaway behaviour of MCAS due to a stuck AOA sensor.

This discussion is around a not previously considered human/machine feedback process, driven by a delayed trim unwinding process, and subject to interruption by pilot trim inputs. This point seems not to have been covered in any other forum, other than the brief hint, and useful chart, referenced earlier in this thread.

This may turn out to be a non-issue, if properly implemented and documented. It is definitely the kind of concern to be discussed by the Joint Authorities Technical Review.

AF447 impacted the manufacturer not because of ethnicity issues but BECAUSE THE VICTIMS, PILOTS AND THE AIRLINE WERE SITED IN THE COUNTRY THAT BUILT THE PLANE AND CERTIFIED IT. So basically everyone concerned ended strung up in front of the same investigation system with an angry populace, and investigators could speak to all actors, and in the end everyone got blamed, AF for not swapping out the pitots, the pilots for winning the Darwin award, and the manufacturer for a tech failure and bad ergonomics.

In the case of the Max, the issue of "foreign carriers, foreign pilots" is getting raised as a way for Boeing and the FAA critters to wrangle their way out of a proper accounting for a design and certification process failure, with the dog whistle that the "foreigners" shouldn't be allowed to cash in on the liability payments generously provided by US courts to US victims.

Everyone here is very aware that if 400 US citizens had died in 2 plane crashes, Boeing would be facing serious financial consequences, and there would be a real congressional inquiry re. the FAA's somewhat lax certification practices.

Nobody anywhere in the world believes that the pilots on board the two sadly doomed airframes were anything other than perfectly average trained individuals. In fact Boeing's customers mostly employ pilots of average abilities, because they employ a lot of pilots. There may be some retired fastjet pilots in the trade, but they are now outnumbered by civilians.

Interestingly, on this forum, pilots seem to blame the Max pilots for not flying their planes, while engineers blame the design and the process. Quite possibly both are correct.

Edmund

I'd be very interested to see a reference that says that.

I can't find primary references stating that, other than the text and chart by LEOCh previously mentioned: https://www.pprune.org/rumours-news/618252-boeing-737-max-software-fixes-due-lion-air-crash-delayed.html#post10423226

The best simple description is a single sentence from b737.org.uk: 737 MAX - MCAS
Edit: There is an intriguing extra sentence (mangled meaning?) about the proposed improvements:

Thanks for that. It does sound rather counter-intuitive that as soon as AoA drops below the threshold for MCAS commanding AND trim, it then does the opposite.

I note that the extract from the Max System Differences Training Manual (presumably a Boeing publication) on Chris's site makes no mention of MCAS commanding ANU trim:


https://cimg7.ibsrv.net/gimg/pprune....82503bd83a.jpg
http://www.b737.org.uk/images/mcas-mtm.jpg

Yes, several people (including myself) have pointed out that definition leads to an "unstable" outcome when AOA fluctuates close to the 10 degree threshold. Not an elegant algorithm at all...

The more that comes out - the simple power and pitch pilots will save the day, seems less likely as hidden automation seems to kill those egos.

MCAS version 1 had big problems - version 2 has the same but different problems.

Just recall guys no, or low MCAS input = possible flight outside certification limits within the flight envelope is possible. Thus pitch and power is not relevant as it is not proven and unless you are a Test Pilot commenting on 737 flight outside the certification limits is no more relevant than a pax.

Clearly even today MCAS is not understood and there seem many secrets - that should have never been the case. But it seems to be the future.

Correct, but there are multiple credible sources saying effectively the same thing. It was in point (1) of FCEng84's long clarification post earlier in thread: link

FCEng84 has posted good, readable, and apparently accurate information on MCAS from the start, I haven't had reason to dispute any of the other information so I would tend to trust this part too.

There are a handful of skygods on here who continuously say "they should have" or "all they needed to do was" or "I would have just" and so on.

In my opinion, pilots with these outlooks are less than safe.

They have a high opinion of themselves.
They have not appreciated the HF elements of these accidents.
They have not considered how HF will affect their operation, in the event of a serious problem.
They are therefore not prepared.

If we just blame the pilots for being a bit crap, then nothing in the industry will improve. We need to understand why these pilots, despite all of their efforts, could not keep the aircraft from the ground. Only when we understand, can we make the correct changes to stop it happening again.

Even the finest pilots in the world, when suddenly presented with a simple failure (double engine failure, for example), will sit there and think "no - this can't be happening" followed by "what on earth do I do".

It is inexcusable that Boeing and the FAA allowed a pretty ropy old aircraft with some dodgy characteristics to be released with even poorer characteristics. It is a demonstration of how multiple signals during a critical phase of flight can make it very difficult for pilots to overcome startle, then diagnose, fly and solve a problem.

As an aside - in my airline it was discovered that UAS events were handled badly. So in one sim cycle we were trained. In the next sim cycle we were tested, and still it was handled badly. So in the next sim cycle again we were trained a lot more. It transpires that real UAS is really a HF event of great complexity, and is therefore very difficult to get right. The technical side of it is a doddle.

Can we please focus on how we contribute to make the industry better (safer)?

There have been plenty of other cases of commercial airline instrument failures leading to unexpected system responses and confusion among the crew. You just don’t hear about them because these events had a successful conclusion.

That's a diversionary response. This was not just a case of "unexpected system responses". MCAS commandeered the most powerful control surface on the airplane and, in effect, caused an intermittent runaway, something for which nobody was trained.

I understand that, and cannot find an official Boeing source. But think about this scenario for one minute:
An "undocumented" maneuver augmentation system that leaves the nose trim 2.5 degrees lower than when it started.
Do you think Boeing would ever release that?
Do you think the FAA would ever certify that?
Logic dictates that your version makes no sense, for a feature which everyone agrees is not an anti-stall system.

I would say the MCAS trim must be reset to the original place to comply with the certification requirements. When control force is released the airspeed must return to within a small percentage of the original trim speed and also a push on the column be needed to achieve a speed below that original trim speed.

Most incidents are resolved OK but here are three other crashes where the published cause seems questionable.

https://en.wikipedia.org/wiki/Kenya_...#Investigation

https://en.wikipedia.org/wiki/Ethiop...nes_Flight_409

https://en.wikipedia.org/wiki/EgyptAir_Flight_990

Well said, totally agree

Fly the damn aircraft