737 MAX future

[ATC Watcher]

Notice all 3 threads are closed , a good mod decision to merge the 3 , and indeed some of the discussions became a bit personal but these threads have seen very valuable discussions and were a very valuable source of info from the US newspapers covering the issue ( WSJ, NYT and especially Seattle times) which are not all available in many countries.
With the aircraft still grounded it would be nice to continue to have a constructive discussion both on the still coming proposed fix but basically on the future of the Max.

on that point , heard in a waterhole last night that Norwegian is transferring a large parts of their Max crews for conversion training on the 787s.. not sure what it means for the long term.

[Bend alot]

Notice all 3 thread closed , a good mod decision to merge the 3 , but why close it ? pressure from Boeing ? there threads have had very valuable discussions and a very valuable source of info from the US newspapers covering the issue ( WSJ, NYT and especially Seattle time s, not all available in many countries.
With the aircraft still grounded it would be nice to continue to have a constructive discussion both on the still coming proposed fix and basically on the future of the Max.

Agreed ATC. If the MAX is not aviation news, I do not know what is.

I looked else where today and found some interesting stuff on other web pages, a really good post from a pilot (as well as other accomplishments) regarding the grounding of the 737 MAX aircraft or Grounding the MAX 737 pilots.

Almost daily, new news was being presented in relation to Boeing, Max, FAA and customers not to mention some excellent feed back from 737 and MAX 737 pilots and some people that seemed "in the know" regarding engineering.

[Loose rivets]

I read every post from the first day and became fascinated by the detective work - but there was a need to bring to a halt the many circular arguments.

Since it is such a vital issue for world aviation, and this is a worldwide forum, could we not establish a thread with a set of known items that could sit at the front end? Graphs, function of relays, what would happen when we do so-and-so. Ideally, two such threads, one specifically technical. This part would be there once for perpetual reference and could be updated by the OP by installing posts by others that could then be deleted.

The big problem with the original was that you could not expect the average newcomer to read it, so their bright ideas were just a yawn-inducing noise.

If folk new that rambling on about something repeatedly would just met with RTFSticky, then perhaps a lot could be achieved in a 1000 posts, and not to put too larger emphasis on it, it would be a real service to aviation. I think it probable a lot of 737 pilots have read it even if not contributing. And this would be carried on by word of mouth.

The problem is, one can't edit such a first post unless one is the OP, so again the workload would fall on the mods. A lot of workload. So, I'm not sure how it would be achieved, but something like that.

[Alchad]

Bend Alot

Would you mind sharing the link?

thanks

[Loose rivets]

To a great extent, Bend's post describes a lot of what was happening here. The three major publications providing a lot of Seattle information. Mentor and Peter Lemme's contributions were interesting, but then there'd be a gap and their very content would be being questioned anew.

[Bend alot]

Bend Alot

Would you mind sharing the link?

thanks
I shall find it again and link it here if this thread remains open - it was very good to see him present both sides extremely well, for the same argument.

[Trav a la]

This news article says B knew about the software problem about a year ago.

https://www.foxnews.com/us/boeing-knew-about-safety-alert-problem-for-a-year-before-telling-faa-airlines

[Zeffy]

https://www.nytimes.com/2019/05/08/business/boeing-737-max.html

With 737 Max, Boeing Wants to Win Back Trust. Many Are Skeptical.
By Natalie Kitroeff and David Gelles
May 8, 2019


A charm offensive by Boeing to persuade airlines, crews and passengers to rally behind its 737 Max plane is already running into resistance.

The effort, which includes daily calls with carriers as well as meetings with pilots and flight attendants, is being hampered by a problem of the company’s own making. After a bungled response to two deadly crashes involving the jet, Boeing is facing credibility problems.

When Boeing dispatched one of its top lobbyists, John Moloney, to the headquarters of the influential union representing flight attendants a couple of weeks ago, he arrived determined to win their support. He met a skeptical audience.

“Reading your body language, you look cynical,” Mr. Moloney said, according to three people who were present and took notes during the discussion with the Association of Flight Attendants. “If this explanation doesn’t address your concerns, I’ll come back. I’ll bring a pilot.”

Sara Nelson, the head of the union, told Mr. Moloney that she was rooting for Boeing, but wasn’t ready to tell flight attendants and travelers to fly on the Max.

“I don’t know, sitting here right now, that I can tell you there’s complete confidence that everything’s been fixed at Boeing,” she told Mr. Moloney.

The meeting, punctuated by contentious moments between the two sides, underscores how difficult it will be for Boeing to restore credibility with airlines and passengers.

In recent weeks, the company’s chief executive, Dennis A. Muilenburg, updated the heads of Southwest Airlines, American Airlines and United Airlines — the three carriers in the United States that fly the Max — on progress. On Tuesday, Boeing held a meeting in Amsterdam for European airlines to discuss new training for the Max, plans for a public affairs campaign and how to get idled planes ready to fly again. Similar meetings will happen in Shanghai, Singapore, Moscow, Dubai and Miami in the coming weeks.

Boeing, a juggernaut with deep ties in Washington and one of the country’s largest exporters, is on the defensive. The company is facing multiple federal investigations into design flaws that contributed to the accidents, along with a spate of lawsuits from the families of victims. Company executives and board members are deeply worried about the damage that has been done to Boeing’s once-sterling reputation.

“Certainly there’s concern,” David Calhoun, the lead independent director of Boeing’s board, said in an interview. “There is recognition on all of our parts that we’re going to have to get out with restoring confidence in the Boeing brand broadly for years.”

But there’s a limit to how much Boeing can say. “It’s an impossible situation because we’re not allowed to comment on anything related to these accidents,” Mr. Calhoun said.

“There’s only one thing to do, and that’s to get a safe airplane back up in the sky,” he said. “I can’t message my way into it. Boeing can’t message its way into it.”

Boeing has been working furiously to get the Max flying again since its grounding in March. The company is preparing to submit a software fix in the coming weeks for American regulators to approve.

It hosted hundreds of airline officials and pilots last month at the 737 Max factory in Renton, Wash. And it is in constant dialogue with regulators ahead of a meeting that the Federal Aviation Administration will host with global aviation authorities in Fort Worth on May 23.

“Ultimately, the decision to return the Max to commercial service rests in the hands of global regulators,” Gordon Johndroe, a Boeing spokesman, said in a statement.

Simultaneously, Boeing is shaping a public relations strategy to reach passengers. Although the final media plan is still in the works, Boeing will not be relying solely on its executives to win back the public’s trust — a recognition that its leadership has lost some good will.

The company and airlines agree that the chief executive, Mr. Muilenburg, as the face of a company under intense scrutiny, may not be the most effective messenger. Instead, the initial plan calls for pilots to play a major role in the campaign.

“We think a key voice in all of this will be the pilots for our airlines, and their voice is very important,” Mr. Muilenburg said on Boeing’s earnings call last month. “That bond between the passenger and the pilot is one that’s critical, and so we’re working with our airline customers and those pilot voices to ensure that we can build on that going forward.”

Boeing has enlisted media agencies, including Edelman, to plan the strategy for reintroducing the Max, and is considering buying ads to promote the plane.

Airline executives in the United States are eager for the Max to return to service and for Boeing to succeed. But many are privately frustrated with the company’s handling of the crisis, according to three people briefed on the matter. They believe that Boeing has badly mismanaged the public response to the crashes and are irked that the public relations blitz will fall to their pilots.

Pilots, too, are reluctant to become brand ambassadors for Boeing, which barely interacted with them before the Lion Air crash in Indonesia last October, the first of the two deadly accidents.

“Our response is, yeah, that’s cute, but we aren’t going to hop into bed with you,” said Mike Trevino, the spokesman for the Southwest Airlines Pilots Association. “We are still going to maintain an independent voice and call it as we see it.”

In part, the reluctance stems from Boeing’s mixed messaging. Despite having said, “We own it,” Mr. Muilenburg has not acknowledged that anything was wrong with the design of the 737 Max, saying that the design process followed standard procedures.

“We clearly have areas where we need to improve, including transparency,” Mr. Johndroe, the Boeing spokesman, said in a statement.

During the meeting last month, the flight attendants pushed Mr. Moloney to explain why the company didn’t inform pilots about the software that contributed to both crashes. He acknowledged that Boeing should have told them, but kept reiterating that pilots were expected to be able to handle the conditions on both doomed flights.

Passenger groups have demanded that Boeing take more responsibility for the Max debacle. “If they really wanted to fix the problem, you would think they would admit that it’s their fault,” said Paul Hudson, the president of Flyers Rights, a nonprofit group advocating for passengers. “You can’t say, ‘Oh, we own it, but we didn’t do anything wrong and it’s someone else’s fault.’”

Pilots and airlines say Boeing has also struggled to communicate with them about how basic systems on the Max work. After the crash in Indonesia, pilots criticized Boeing for not informing them about the new software, which automatically pushes down the nose of the plane when the system deems it necessary. They have also been concerned by revelations that Boeing provided incomplete information about features in the cockpit.

This week, Boeing said it believed a key cockpit warning light was standard on all Max jets, but learned several months after beginning deliveries in 2017 that the light worked only if airlines had bought a separate feature, known as the angle of attack indicator. Southwest bought the plane without the indicator, on the assumption that the warning light was activated. It was only after the Lion Air accident that Boeing told regulators and some pilots that the light wasn’t functional.

Boeing told United something else entirely, creating even more confusion over Boeing’s understanding, according to a person who took notes at the meeting. When United Airlines ordered 100 Max jets in 2017, Boeing told United that the alert and the angle of attack indicator came as a package deal. United declined the options at the time.

“Every day it seems like a new set of questions pops up,” said Dennis Tajer, a spokesman for the union representing American Airlines pilots. “I’m not here to be your arm candy. I’m here to know about the airplane.”

Toward the end of the meeting with the flight attendants, Mr. Moloney made a last-ditch effort to win them over.

“We want you to be able to tell your members this plane is safe to fly,” Mr. Moloney said, according to the three people in attendance. “Whatever it takes.”

Ms. Nelson, the union’s leader, rattled off a list of things she needed from Boeing before agreeing. One was a letter from engineers working on the software update, saying they felt confident in the fix. Another was a full-throated apology from Boeing. Mr. Moloney promised to follow up.

“We think that Boeing’s credibility directly relates to the credibility of U.S. aviation,” Ms. Nelson told him. “It’s important to us that the credibility and the leadership of U.S. aviation is maintained around the world.”

A version of this article appears in print on May 9, 2019, on Page B1 of the New York edition with the headline: Boeing’s Tough Sell: Trust Us.

[Bend alot]

https://www.nytimes.com/2019/05/08/business/boeing-737-max.html
Yet more news information on the 737 MAX.

[A0283]

plans for a public affairs campaign

I dont think part of the aerospace professionals community is waiting for such a "campaign". It is far too late for that. These quoted words alone puts off people even further.

As I posted early on in the initial thread ... Boeing would have been wise to let the 'chief engineer with actual signature responsibility' (so not a manager, not even the CEO, and certainly not 'slick or legal talkers') publicly and clearly explain what Boeing had done before the accidents happened. That would not have been in conflict with the running investigations. The lack of timely and trustworthy information at an early stage has eroded confidence in many quarters. Even to this day Boeing information is lagging what is available and discussed in professional circles.

Openness is safety. Boeing has historically been able to be both more open and legally 'correct' at the same time.

What the Boeing approach seems to forget is that after 'the public' hears something that many people check up with professionals to further explain it to them. Questions like where do I sit and who should I fly with, have changed in how do I recognize a MAX, how do I recognize a 737, and are other Boeing aircraft even safe to fly with.

A new question among professionals is - did Boeing v1.0 morph into a Boeing v2.0 and when ... did it start with the 787 or is something else going on ... and what does it mean for the other designs ... for existing aircraft and future aircraft like the 777X...

It appears Boeing has to act much faster and much clearer or this goes out of hand even further.

One step further than this and we are talking about strategic and systemic failure, where both certainly include Boeing and the FAA and are now dragging in airlines too.

[dirk85]

https://www.bloomberg.com/news/features/2019-05-09/former-boeing-engineers-say-relentless-cost-cutting-sacrificed-safety

[krismiler]

heard in a waterhole last night that Norwegian is transferring a large parts of their Max crews for conversion training on the 787s

Norwegian are having engine issues with their B787s and are looking at possible redundancies. Already financially shaky they've been hit with a double whammy of two duff aircraft types in their fleet.

https://simpleflying.com/norwegian-pilot-redundancies/

[Ancient Mariner]

“We think a key voice in all of this will be the pilots for our airlines, and their voice is very important,” Mr. Muilenburg said on Boeing’s earnings call last month. “That bond between the passenger and the pilot is one that’s critical, and so we’re working with our airline customers and those pilot voices to ensure that we can build on that going forward.”
Since the only interaction between pilot and pax these days seems to be a, frequently muffled, PA I'm not so sure about that.
Per

[AviatorDave]

Since the only interaction between pilot and pax these days seems to be a, frequently muffled, PA I'm not so sure about that.
Per

Part of the problem are pax who generally don‘t like to be bothered, and are unappreciative even if important safety-related information is conveyed.
Brings us quickly back to the thread on how pilots are perceived by the flying public.

[Eddie Dean]

Boeing for a lot of reasons, believe that two serviceable aircraft were flown into the ground.

[YYZjim]

An important step in the re-gaining trust process will be for pilots to think through how the Lion and Ethiopian pilots would have coped if they had been using Boeing's MCAS fix (whatever it turns out to be). Two things have to happen first.

1. Boeing (or somebody) will have to disclose a lot more detail about MCAS-as-was and MCAS-fixed. For example, what does Boeing think caused the constant mismatch between left and right AOA sensors?

2. The CVR transcript and DVR dataset will have to be made public. The bits disclosed in the preliminary reports simply aren't detailed enough to figure out what the pilots did, and why.

Boeing's PR-campaign is no substitute for a hard-headed look by some independent engineers and pilots, Like those on this forum.

Unfortunately, the rules governing accident investigations don't permit releasing the data at this time. Somebody (or Boeing) will have to take the bull by the horns
to get the data out. The sooner it's out, the sooner the MAX can fly again.

YYZjim

[racedo]

Boeing is in the tank for probably $5-10 billion because no matter what it does the public believes it frigged the software to sell aircraft.

Reality is irrelevant as public opinion does not rely on reality but perception and their perception is Boeing is lying.

I think Max will eventually fly again but we are a long way off from it and trust is the key issue here, there is none with Boeing and no amount of PR will win it back easily.

[737 Driver]

I think Max will eventually fly again but we are a long way off from it and trust is the key issue here, there is none with Boeing and no amount of PR will win it back easily.

Based on historical experience, the MAX will be certified to fly again, there will be some initial public avoidance, but after a year (maybe less) most passengers will get over their qualms and the MAX will continue to roll of the assembly line for year to come. This assuming, of course, no other ugly issues raise their heads. Hopefully the folks at Boeing will engage in some deep soul searching and finally figure out that doing it right the first time is far cheaper in the long run than doing it quick.

[Ian W]

Boeing for a lot of reasons, believe that two serviceable aircraft were flown into the ground.



Assumptions made on how pilots would behave have proved unsafe -
Or to put it another way there is a huge problem with training - at all levels from ab initio to continuation training both live and simulated.

[GordonR_Cape]

https://www.bloomberg.com/news/features/2019-05-09/former-boeing-engineers-say-relentless-cost-cutting-sacrificed-safety

Another Bloomberg article about damage to the MAX brand, and the potential long term consequences for Boeing: https://www.bloomberg.com/news/articles/2019-05-10/boeing-fights-to-bring-737-max-back-from-ford-pinto-like-taint

[Cows getting bigger]

Boeing for a lot of reasons, believe that two serviceable aircraft were flown into the ground.



There is a mammoth thread on the military side about an RAF CH47 crash some 20 years ago. Suffice to say, there's a big difference between Serviceable and Airworthy.

[Water pilot]

Boeing for a lot of reasons, believe that two serviceable aircraft were flown into the ground.

A serviceable aircraft was flown into the ground -- by the software.

As a pax I do not really care if a particular type of plane is crashing because of a technical flaw or because current pilots are not skilled enough to fly it. It is all a black box to me, with two possible outcomes; I make it home safely and on time or I do not. If there is some other type that is less likely to crash with the pilots that we have (rather than the pilots that we wish we had), I'll take it and let the enthusiasts bemoan how I selfishly ruined the Pinto a perfectly fine plane.

I find a lot of the actions taken by Boeing to be inexplicable. I'm not particularly of the "hate big companies crowd" (I did quite well at big companies and while executives are not particularly useful in my opinion neither are they particularly venial.) News stories that have come out indicate that the culture is pretty sick right now, and it does lead one to question all of their new projects. I mean really, our meetings would have gone much more easily if we had simply reorganized our test group (the test pilots in Boeing's case) away from engineering! Those testers ask so many annoying questions...

My interest is in design, especially bad design and how we can avoid inflicting more of it on humans. I though that this crash would come down to what appeared to be perfectly reasonable decisions that fit prevailing standards but indicate a generic flaw in the prevailing standards. Instead it seems to be a product of FUBAR engineering which is not what I expected from Boeing or any company not based in San Jose run by three 'bros and a bunch of beer.

[jthg]

Assumptions made on how pilots would behave have proved unsafe -


Lion air and Ethiopian being two stark and terrible examples of this fact.

The perception, at least that being portrayed by the media, is that the truth is far from out there yet and that skeletons remain in the Boeing closet around this entire MAX project.

It has to get worse before it gets better. A lot of very good people stand to suffer if that does not happen

[Smythe]

The 'fix' includes using 2 AoA sensors. That is not a fix. The ac needs 3, so Boeing is minimizing the cost and impact of the fix.

They almost always disagree, so a 3rd is needed in the decision process. What happens if, like in the crash, one is damaged on DEP?

If MCAS is inop can the ac be dispatched? How does a pilot know MCAS INOP?
If the system is not active until 400 AGL, how does a pilot know the system is inop?

Since the first Lion Air incident was on final, where are the parameters for that?

[edmundronald]

Let's face it, the fix is in and nobody cares. Pilots with the right suff are going to pretend they are sure can fly this thing when it fights them, airlines are going to pretend their pilots can fly it without additional sim training, and Boeing is going to pretend they fixed it, and the FAA is going to pretend it's fixed, and the Inspector General is going to believe that the FAA certified the type correctly the first time round, and everyone is going to kick Airbus very hard under the table to make sure the Europeans accept the fix.

After reading this forum, I have come to realize that pilots are smart professionals who care bout flying planes, but do not understand that a bad design puts them in a bad place, and every pilot is convinced that *he* would find the right solution to the mechanical issue that killed his colleagues. The first pages of Tom Wolfe's book The Right Stuff come to mind.

Edmund
PS. I say "he" on purpose. I think the female pilots are probably less testosterone-fueled.

Edmund

[krismiler]

We have 3 artificial horizons in order to have a tie breaker if 1 goes wrong, same with the air speed indicators and usually IRSs. I can't see how 2 AoA sensors will meet requirements if 1 starts acting up. Boeing may have to come up with a completely new stall avoidance system, even if it means recertifying the aircraft as a new type and requiring pilots to obtain a new rating.

[edmundronald]

Let's face it, the fix is in and nobody cares. Pilots with the right suff are going to pretend they are sure can fly this thing when it fights them, airlines are going to pretend their pilots can fly it without additional sim training, and Boeing is going to pretend they fixed it, and the FAA is going to pretend it's fixed, and the Inspector General is going to believe that the FAA certified the type correctly the first time round, and everyone is going to kick Airbus very hard under the table to make sure the Europeans accept the fix.

And then it will crash again.

Edmund

[737 Driver]

The 'fix' includes using 2 AoA sensors. That is not a fix. The ac needs 3, so Boeing is minimizing the cost and impact of the fix.

They almost always disagree, so a 3rd is needed in the decision process. What happens if, like in the crash, one is damaged on DEP?

If MCAS is inop can the ac be dispatched? How does a pilot know MCAS INOP?
If the system is not active until 400 AGL, how does a pilot know the system is inop?

Since the first Lion Air incident was on final, where are the parameters for that?

I got a brief on the new software yesterday. First, I would point out that while a third AOA would be nice, it is not necessary. The 737 has a number of double redundant systems. If there is a disagreement, we get a warning and we refer to a procedure to determine the bad system. We don't need a third AOA to figure out the bad one because we can cross check the airspeeds, mach numbers, altitudes, and power settings for reasonableness. The pilots are, in effect, the "third" system that sorts the good from the bad.

MCAS is part of the Speed Trim System (STS). There are two STS channels, and one is always required for dispatch. If one or both STS/MCAS systems became inop, we receive a warning annunciator on the flight deck. If both systems are inop, the annunciator comes on immediately - it doesn't wait until 400'. If both STS channels fail in flight, we have a non-normal procedure to address it - just like we have non-normals to address the failure of engines, hydraulics, electrics and all sorts of other things we would require for dispatch.

The new Flight Control Computer (FCC) software will inhibit any STS/MCAS input if the difference between AOA's is greater than about 5 degrees. This is more stringent that the current "AOA Disagree" trigger of greater than 10 degrees. The new software also has some other tests for reasonableness. and the total nose down input is adjusted for the conditions - it will input more stab trim at low airspeeds and less at high airspeeds.

Not sure what you are asking with your last question, but maybe it would be a helpful reminder that MCAS only activates with the flaps retracted. If the flight crew is operating the aircraft normally, the flaps will always be extended below 1000 feet.

[737 Driver]

After reading this forum, I have come to realize that pilots are smart professionals who care bout flying planes, but do not understand that a bad design puts them in a bad place,
Edmund


Trust me, we understand fully. There is a saying that goes, "The pilot is usually the first one to the scene of the accident." Pilots all want to operate planes that don't malfunction, but we also understand that some days we don't get our wish.

[krismiler]

Any fix is going to have to be belt and braces, bullet proof if confidence is going to be restored in the MAX. It will have to cover the lowest denominator airline flying the type not just major airlines in first world countries. A minimum standard solution might get it back in the air but cause future orders to dry up and heaven help Boeing if another one crashes.

[Loose rivets]

At the end of the day, MCAS will still be able to make inputs to a 47' flying surface. We read that these commands are to be substantially modified, fine, but still that black box has the potential to house HAL. Just how does one construct an impenetrable wall that will stop millions of junction gates from a catastrophic conspiracy - one that no one has filtered out of thousands of lines of code - one that won't show up for months or even years? My feeling is that its connection to the stabilizer should be totally removed and do nothing but warn. But then of course there's STS, MCAS's senior logic layer. That's worked okay for years but it's the sheer power of that flight surface that makes my aged sphincter-system lock up.

Even the basic premise seems bizarre to me: in certain circumstances we want to stop the elevators becoming steadily lighter, so we pitch an entire aircraft nose down? Height, flaps zero, AP off, speed within range and a complex system of relays etc., should all stop that signal going to the tail, but the potential for unwanted activation is hard wired into that aircraft for life.

[Bend alot]

I got a brief on the new software yesterday.

MCAS is part of the Speed Trim System (STS). There are two STS channels, and one is always required for dispatch. If one or both STS/MCAS systems became inop, we receive a warning annunciator on the flight deck. If both systems are inop, the annunciator comes on immediately - it doesn't wait until 400'. If both STS channels fail in flight, we have a non-normal procedure to address it - just like we have non-normals to address the failure of engines, hydraulics, electrics and all sorts of other things we would require for dispatch.

The new Flight Control Computer (FCC) software will inhibit any STS/MCAS input if the difference between AOA's is greater than about 5 degrees. This is more stringent that the current "AOA Disagree" trigger of greater than 10 degrees. The new software also has some other tests for reasonableness. and the total nose down input is adjusted for the conditions - it will input more stab trim at low airspeeds and less at high airspeeds.

Not sure what you are asking with your last question, but maybe it would be a helpful reminder that MCAS only activates with the flaps retracted. If the flight crew is operating the aircraft normally, the flaps will always be extended below 1000 feet.

There was the Boeing spokesman that said the AoA disagree only worked above 400ft after they found it actually was not active all all.

So if that is true, then how can the MCAS part of the STS be tested before flight? Lion Air seems faulty AoA fitted - would the annunciation illuminate in this case?
The current MCAS AoA had no limit of disagree, and there was no problem withe the STS operation previously - MCAS really looks more than just a sub-sytem of STS.
Now the that is worrying - variable amounts of input! So if you are going slow with a high angle of attack - how long do you watch that trim wheel spin for?

From the previous thread Mr Driver your instinct would be to trim have you then disabled MCAS and stopped it from its certification requirement?

Would your current practice still stand? - keep flap out, or Autopilot on to bypass MCAS from being able to activate?

[737 Driver]

At the end of the day, MCAS will still be able to make inputs to a 47' flying surface. We read that these commands are to be substantially modified, fine, but still that black box has the potential to house HAL. Just how does one construct an impenetrable wall that will stop millions of junction gates from a catastrophic conspiracy - one that no one has filtered out of thousands of lines of code - one that won't show up for months or even years? My feeling is that its connection to the stabilizer should be totally removed and do nothing but warn. But then of course there's STS, MCAS's senior logic layer. That's worked okay for years but it's the sheer power of that flight surface that makes my aged sphincter-system lock up.

Even the basic premise seems bizarre to me: in certain circumstances we want to stop the elevators becoming steadily lighter, so we pitch an entire aircraft nose down? Height, flaps zero, AP off, speed within range and a complex system of relays etc., should all stop that signal going to the tail, but the potential for unwanted activation is hard wired into that aircraft for life.

I assume that you understand that there's nothing but software between the flight deck and the rest of the aircraft in more contemporary aircraft designs? At least the 737 has a set of braided steel cables between the flight deck and every primary flight control surface that is needed to get the aircraft back down on the ground.

[Bend alot]

Bend Alot

Would you mind sharing the link?

thanks
But if I were speaking as a non-flying member of the public, and as a politician who must answer to them, I would say: ground the fleet now. As far as the public is concerned, the industry had its chance and blew it. I would have no confidence in the plane nor the industry until an explanation is found and the design changed. Nor would I buy a ticket on such a plane.

https://www.theatlantic.com/notes/2019/03/dont-ground-the-airplanes-ground-the-pilots/584941/?fbclid=IwAR1JbX337lOlKC8bEDUEjSgRLSJ7bLEOn-VXTtJFSyRI3HKWMiGTRbWIC3c

[Loose rivets]

Re 737 Driver's post.

Yes, but it's the initial unwanted command to the H-Stabilizer that I take issue with. Should all the protection fail again, and that jack-screw run its full distance, then those braided steel cables seemingly still won't save the day.

I've thought long and hard about fly by wire since 'flying' a model in a box at Farnborough in the 70's Given the sophistication of the electronics, I concede the probabilities make my worries all but groundless, but then there's a hefty lighting strike into the electrics bay scenario which would indeed put Boeing way ahead.

.

[Smythe]

737, Sorry, but I am not in agreement here. I understand you are a pilot, and so are many of us. The parameters and the if/then scenario have never been properly detailed. We would not have 3 incidents and 2 crashes if it had been.

While MCAS is part of the Speed Trim System (STS), the parameters appear completely different.

I know the Boeing ac, but are not current like I am on Airbus ac..

From what I have seen on the STS system, STS Mach gain is fully enabled between 100 KIAS and Mach 0.60 with a fadeout to zero by Mach 0.68. 10 seconds after takeoff, 5 seconds following release of trim switches, and Autopilot not engaged.

IF STS utilizes AoA , then why was MCAS required?

What are the parameters that engage MCAS?

I really do not agree with 2 AoA sensors, and the pilot is not the 3rd sensor, especially if there is only one left for whatever reason (as in the Ethiopian crash). As I have stated before, the AoA's are always in disagreement in many conditions, such as climbout and short final ,and while you claim the pilot has a decision, well, where or what is that decision based?
Lose 1 out of 2 sensors, and what is your decision based on?

Those AoA vanes always have issues and you know it.

[737 Driver]

There was the Boeing spokesman that said the AoA disagree only worked above 400ft after they found it actually was not active all all.

So if that is true, then how can the MCAS part of the STS be tested before flight? Lion Air seems faulty AoA fitted - would the annunciation illuminate in this case?
The current MCAS AoA had no limit of disagree, and there was no problem withe the STS operation previously - MCAS really looks more than just a sub-sytem of STS.
Now the that is worrying - variable amounts of input! So if you are going slow with a high angle of attack - how long do you watch that trim wheel spin for?

From the previous thread Mr Driver your instinct would be to trim have you then disabled MCAS and stopped it from its certification requirement?

Would your current practice still stand? - keep flap out, or Autopilot on to bypass MCAS from being able to activate?

In this operator's opinion, certainly not shared by all, the "AOA Disagree" alert that has captured so much attention is not that bid of a deal. If the AOA's are really that far apart, there will be sufficient other indications because of how the AOA information is integrated into other aircraft systems. In the case of both Lion Air flights and ET302, an active stick shaker while the aircraft is accelerating and climbing normally is the big, annoying, and very obvious indication that something is amiss with your AOA system - and that becomes active as soon as the aircraft lifts off the ground.

I'm not sure about what you mean about testing STS/MCAS before flight. There are various logic tests going on in the background for many of our onboard systems, and we will get warning annunciators if one of those self-tests fails. Otherwise, most of our systems are assumed to be working until proven otherwise.

I don't see what is worrying about variable amounts of input. If the system is working and you really are approaching a stall, then that is what you want. If the system somehow got past the new software checks, then MCAS would be making an input when there was no stall while the pilot was hand-flying. As discussed in other threads, the pilot should notice such an anomalous input and take corrective action. At some point, you have to assume that someone is minding the store. If not, there are other systems on the plane that you should be far more worried about.

To your question of what I would do with an unwanted MCAS input, it would be the exact same thing I would do with any unwanted stab trim input. By my count, there are six different sources of input into the electrically-driven trim system on the MAX (five on the 737NG). Our runaway stab procedures are completely agnostic to the source of the undesired trim. Step 2 of that procedure is to oppose and counter the unwanted trim with the yoke trim switch. It is not until Step 5 that the cutout switches are used. This was one of the errors the ET302 crew made - they went right to Step 5. Once MCAS is disabled, yes, the aircraft no longer meets its certification dispatch requirement. That statement also applies when we lose engines, hydraulic systems, generators, and so forth. That is why we have non-normal procedures to get the aircraft back on the ground where it can be fixed.

The technique I spoke of before about engaging the autopilot before flap retraction was an interim approach until Boeing rolled out a long term fix. That will no longer be necessary with the new software.

[737 Driver]

Re 737 Driver's post.

Yes, but it's the initial unwanted command to the H-Stabilizer that I take issue with. Should all the protection fail again, and that jack-screw run its full distance, then those braided steel cables seemingly still won't save the day.
.

If the jackscrew reaches the limit, then someone was very seriously not paying attention. The problem in that case is not with MCAS.

[737 Driver]

737, Sorry, but I am not in agreement here. I understand you are a pilot, and so are many of us. The parameters and the if/then scenario have never been properly detailed. We would not have 3 incidents and 2 crashes if it had been.

While MCAS is part of the Speed Trim System (STS), the parameters appear completely different.

I know the Boeing ac, but are not current like I am on Airbus ac..

From what I have seen on the STS system, STS Mach gain is fully enabled between 100 KIAS and Mach 0.60 with a fadeout to zero by Mach 0.68. 10 seconds after takeoff, 5 seconds following release of trim switches, and Autopilot not engaged.

What are the parameters that engage MCAS?

I really do not agree with 2 AoA sensors, and the pilot is not the 3rd sensor, especially if there is only one left for whatever reason (as in the Ethiopian crash). As I have stated before, the AoA's are always in disagreement in many conditions, such as climbout and short final ,and while you claim the pilot has a decision, well, where or what is that decision based?
Lose 1 out of 2 sensors, and what is your decision based on?

Those AoA vanes always have issues and you know it.

I can't quote chapter and verse the MCAS engagement parameters since that information has yet to be published. As a practical matter, however, pilots don't memorize all these numbers and then mentally cross-check what the STS/Mach Trim/MCAS is doing. The trim wheel is making adjustments all the time during a normal flight (probably the same on an Airbus), and the trim is either appropriate for the conditions or it isn't. If the trim isn't appropriate, then it should become apparent fairly quickly - again if someone is paying attention. And if someone is not paying attention, then there are much bigger potential issues than MCAS waiting in the wings.

Yes, it would be great if we had triple-redundancy on everything on the 737. However, I must point out that it has relied on double-redundancy with a pilot as tiebreaker for, well, ever since the plane has been flying. It is pretty much a fact of life on the 737, and it really hasn't been an issue. If I lose one of anything, there is always a way to figure out which one is working and which one isn't.

[Big Pistons Forever]

My sad prediction:

The next Max crash will involve a 3rd world airline without mature Western Airline training and experience with a crew so hyper vigilant about a MCAS runway that they will misdiagnose something else as a MCAS failure go to the stab cut out switches and now have to manually trim an out of trim aircraft, which is basically never done, get behind the airplane and fly it into the ground......

[Bend alot]

Mr Driver, Thanks for answering so many questions it really is appreciated.

I was more trying to see if if there was a self test of the STS system including MCAS (short of moving the vanes).

Obviously it would be preferable to know such things prior to take-off and or 400ft including that pesky stick shaker.

Should an AoA disagree (more than 5 degrees) MCAS can not function, so (and I am aware you stated you would not put them up) is flight with flaps up prohibited?

Did the brief include the conditions of MCAS override by the pilot/s and rest limits?

[Matt48]

https://www.nytimes.com/2019/05/08/business/boeing-737-max.html

A 'body language expert', they clearly sent the wrong person.

[737 Driver]

Should an AoA disagree (more than 5 degrees) MCAS can not function, so (and I am aware you stated you would not put them up) is flight with flaps up prohibited?

Did the brief include the conditions of MCAS override by the pilot/s and rest limits?

If there is an AOA disagreement that is enough to inhibit MCAS, then we would get a warning annunciator and we would follow the non-normal procedure for that annunciation. It is my understanding that the non-normals are being adapted for the new software, but they have not been published so I can't really comment on them. If the MCAS has been inhibited, there really should be no issue with retracting the flaps. Keep in mind that the entire reason MCAS exists is to assist in certain circumstance when the aircraft approaches a stall. Commercial aircraft fly thousands of segments per day for weeks, and months, and (sometimes) years on end without a single one of them approaching a stall. A situation where MCAS is not available for a particular flight has a risk probability that is quite low.

Again, if MCAS were somehow to activate when it was not supposed to with the new software in place, the response would probably still be the runaway stab trim procedure. I say "probably" because until the MAX is certified for flight, there may be new procedures developed.

[Bend alot]

However, retracting the flaps could (regardless of risk level) allow the aircraft to be flown in a condition that is known not to be certifiable.

One would expect that the aircraft could not be certified (?) with flaps retracted.

I think this will be the sticking point, the aircraft NEEDS MCAS, the fix has introduced many ways to limit and deactivate MCAS.

Nothing has changed, only the thing that is required is often not available anymore.

It is not just a case of the aircraft is safe to fly, but it must fly like it's little brother, in every part of the envelope all the time - and it can not do this without an active MCAS.

I think for certification it needs a fail safe system that keeps MCAS alive or very low probability of being shut down.

The fix is to remove MCAS basically! When we can all see by the data that it operated exactly as it was told (designed) to do - MCAS never made an error! 3 inputs would be a clever option.

[737 Driver]

However, retracting the flaps could (regardless of risk level) allow the aircraft to be flown in a condition that is known not to be certifiable.

One would expect that the aircraft could not be certified (?) with flaps retracted.

I think this will be the sticking point, the aircraft NEEDS MCAS, the fix has introduced many ways to limit and deactivate MCAS.

Nothing has changed, only the thing that is required is often not available anymore.

It is not just a case of the aircraft is safe to fly, but it must fly like it's little brother, in every part of the envelope all the time - and it can not do this without an active MCAS.

I think for certification it needs a fail safe system that keeps MCAS alive or very low probability of being shut down.

The fix is to remove MCAS basically! When we can all see by the data that it operated exactly as it was told (designed) to do - MCAS never made an error! 3 inputs would be a clever option.

I hear what you're saying, but let me try this again with a simple example.

To be certifiable (and more to my way of thinking, cleared for dispatch) the 737 needs two functioning Inertial Reference Units (IRU). During the flight, let's say one of the IRU's fail. At this point, the aircraft is no longer "certifiable." However, I'm already in the air, so I pull out the appropriate non-normal checklist (which is quite involved), and let's say I am unable to reset the unit. I will then throw a switch to put both sides on a single IRU and continue to destination under certain additional restrictions. Once the plane is on the ground, it will stay on the ground until the faulty IRU is fixed or replaced. The same logic can be applied to numerous aircraft systems, not just the MCAS.

Every system on the aircraft is subject to failure, and some of those failures will put the aircraft out of its certifiable limit. The manufacturer does not eliminate those systems, but rather they develop non-normal procedures to deal with the failure until the aircraft is on the ground and the system can be repaired. This is the way it has been done in aviation since before I took my first flight.

There are certain components (like the wing) that really do fall in a fail-safe category, and they necessarily meet a much a higher standard. MCAS is not one of those items.

[Smythe]

To be certifiable (and more to my way of thinking, cleared for dispatch) the 737 needs two functioning Inertial Reference Units (IRU).


To be certified to fly, MCAS needs to be operational to be dispatched.

I see they have initialized the optional AoA dial on the flightdeck, and a light when AoA does not agree...(at 400 AGL?)

How does one determine MCAS is operational to dispatch? It must be on the ground, correct ? you cannot dispatch with a non-normal condition.
Have they added a MCAS INOP check prior to DEP?
Have they initialized MCAS on the ground (instead of 400 AGL?)
How can you check the operation of the AoA vanes while on the ground? (they all show 90 degrees?)

As part of the 'fix' there will be an AoA measurement shown on the screen. And this means what? As the saying goes, what would you do with the AoA measurement if you had one? Is is it showing the wing AoA or the fuselage AoA? How many pilots know the AoA of the wing vs the fuselage AoA?
Do pilots know the AoA and/or conditions when the engine nacelles provide the sudden pitch up?

How long have pilots been asking for the AoA ?

MCAS relies on the AoA vane measurements, which in reality, ac dont even report the AoA angle (case in point) nor has anyone paid that much attention to, yet now the automation does, and there begins the disconnect.

We are Boeing.
Resistance is futile
You will be assimilated.

[Bend alot]

I hear what you're saying, but let me try this again with a simple example.

To be certifiable (and more to my way of thinking, cleared for dispatch) the 737 needs two functioning Inertial Reference Units (IRU). During the flight, let's say one of the IRU's fail. At this point, the aircraft is no longer "certifiable." However, I'm already in the air, so I pull out the appropriate non-normal checklist (which is quite involved), and let's say I am unable to reset the unit. I will then throw a switch to put both sides on a single IRU and continue to destination under certain additional restrictions. Once the plane is on the ground, it will stay on the ground until the faulty IRU is fixed or replaced. The same logic can be applied to numerous aircraft systems, not just the MCAS.

Every system on the aircraft is subject to failure, and some of those failures will put the aircraft out of its certifiable limit. The manufacturer does not eliminate those systems, but rather they develop non-normal procedures to deal with the failure until the aircraft is on the ground and the system can be repaired. This is the way it has been done in aviation since before I took my first flight.

There are certain components (like the wing) that really do fall in a fail-safe category, and they necessarily meet a much a higher standard. MCAS is not one of those items.

Yes I hear you, but.
You have two functioning IRU's and with one going U/S, you are left with one IRU - the aircraft will function happily with one and there are no parameters of flight that will change. This is redundancy two "required" only one needed. Same with numerous of items like computers, one goes u/s the aircraft operates the same.

MCAS has no redundancy, and if there is a failure of MCAS the flight characteristics do change in certain areas of the envelope. You just will not know how abruptly or placid this change might be until you find yourself there (that may never happen just like an engine failure after take-off) or even amount of change v/s speed. What is the difference in a turn? will it try roll you also?

It is a bit like the flap selector braking off in your hand, no second handle. But the big difference is you know how the aircraft will fly regardless of the setting the handle broke. Chances are you had to do a flap-less landing during your original training - but I doubt for a broken handle! but you practice it at some stage.

Considering this all happens close to the stall and in manual flying condition. A condition almost prohibited at some airlines these days, the very least we expect is that the pilots have trained and practices for these known change of characteristics. But we all know that is not a consideration to be had.

[hans brinker]

To be certified to fly, MCAS needs to be operational to be dispatched.

I see they have initialized the optional AoA dial on the flightdeck, and a light when AoA does not agree...(at 400 AGL?)

How does one determine MCAS is operational to dispatch? It must be on the ground, correct ? you cannot dispatch with a non-normal condition.
Have they added a MCAS INOP check prior to DEP?
Have they initialized MCAS on the ground (instead of 400 AGL?)
How can you check the operation of the AoA vanes while on the ground? (they all show 90 degrees?)

As part of the 'fix' there will be an AoA measurement shown on the screen. And this means what? As the saying goes, what would you do with the AoA measurement if you had one? Is is it showing the wing AoA or the fuselage AoA? How many pilots know the AoA of the wing vs the fuselage AoA?
Do pilots know the AoA and/or conditions when the engine nacelles provide the sudden pitch up?

How long have pilots been asking for the AoA ?

MCAS relies on the AoA vane measurements, which in reality, ac dont even report the AoA angle (case in point) nor has anyone paid that much attention to, yet now the automation does, and there begins the disconnect.

We are Boeing.
Resistance is futile
You will be assimilated.

Dude, chill....

I fly Airbus, and do not want to fly B737. Having said that, none of my 3 AOA indicators are tested before I am airborne. All my 7 flight computers self test to see if they are ok to fly, just like the FCCs(?) on the 737 will before flight. Does that mean that they will work once I rotate? No, but that is why I am there.

[speedbirdconcorde]

The issues with Boeing run very deep. As with most industries, money (profit) is the only reason they exist. The CEO received more than $24m last year I believe. Just like the medical device industry here in Southern California: FDA or TUV auditors are wined and dined to go easy on the company and turn a blind eye....organizations are allowed to self regulate and report ( hey, how about selling a product, that surgeons use to treat brain aneurysms, to Europe and South America, even though a major shipment of the product contains traces of lead through the ‘fault’ of a third party vendor? Self report ? Hell no!! And the FDA have no idea ). The need (obsession) to meet ever increasing ‘numbers’, to hold off the competition and to keep the stakeholders happy ($$$) ultimately results in complacency that is endemic throughout many industries ( yes...aviation included )....until people die and then the lawyers appear out of the woodwork to begin damage limitation...not out of remorse..but to simply protect the business. The documentary on the 787 below really is a mirror to many other industries. Everyone wants a piece of the pie but without the negative consequences and ownership. Maybe folk will view the 787 video below with even more contempt now we have lost two MAX aircraft...and more importantly...many innocent lives.

Pilots, passengers....all pawns to those playing the big game ( Thank goodness it was a little better during the Concorde years! )

787 broken dreams

[Bend alot]

Dude, chill....

I fly Airbus, and do not want to fly B737. Having said that, none of my 3 AOA indicators are tested before I am airborne. All my 7 flight computers self test to see if they are ok to fly, just like the FCCs(?) on the 737 will before flight. Does that mean that they will work once I rotate? No, but that is why I am there.
That is exactly how your Airbus was certified.

Your Airbus if something fails is still operating within the approved envelope as per certification requirements and required testing/training.

If one of your AoA fail at take off, nothing changes - it fly's the same.

I expect that when two fail, we have a problem? Was that iPad training you took?

The point is not a possible safety issue as most/many pilots have good flying skills and it may well be a non event. The point is when an AoA is U/S the aircraft is known to in certain parts of the envelope to be out of certification limits. Exactly where this is, and it varies it seems the physical effects are not known or experienced by airline pilots.

The basic problem is that the MAX can not meet certification without MCAS - How can shutting down MCAS be a solution?

[BDAttitude]

I got a brief on the new software yesterday. First, I would point out that while a third AOA would be nice, it is not necessary. The 737 has a number of double redundant systems. If there is a disagreement, we get a warning and we refer to a procedure to determine the bad system. We don't need a third AOA to figure out the bad one because we can cross check the airspeeds, mach numbers, altitudes, and power settings for reasonableness. The pilots are, in effect, the "third" system that sorts the good from the bad.

MCAS is part of the Speed Trim System (STS). There are two STS channels, and one is always required for dispatch. If one or both STS/MCAS systems became inop, we receive a warning annunciator on the flight deck. If both systems are inop, the annunciator comes on immediately - it doesn't wait until 400'. If both STS channels fail in flight, we have a non-normal procedure to address it - just like we have non-normals to address the failure of engines, hydraulics, electrics and all sorts of other things we would require for dispatch.

The new Flight Control Computer (FCC) software will inhibit any STS/MCAS input if the difference between AOA's is greater than about 5 degrees. This is more stringent that the current "AOA Disagree" trigger of greater than 10 degrees. The new software also has some other tests for reasonableness. and the total nose down input is adjusted for the conditions - it will input more stab trim at low airspeeds and less at high airspeeds.

Not sure what you are asking with your last question, but maybe it would be a helpful reminder that MCAS only activates with the flaps retracted. If the flight crew is operating the aircraft normally, the flaps will always be extended below 1000 feet.

This is news and this is very important especially the STS MCAS relation thing to be heard by a Boeing representative. Maybe not so much for pilots but for safety engineers and probably lawyers. It has a lot of implications on what has (not) been done and should have been done in the first place and what was state of the art and good practice within Boeing.
A feast.

[Sucram]

We have 3 artificial horizons in order to have a tie breaker if 1 goes wrong, same with the air speed indicators and usually IRSs. I can't see how 2 AoA sensors will meet requirements if 1 starts acting up. Boeing may have to come up with a completely new stall avoidance system, even if it means recertifying the aircraft as a new type and requiring pilots to obtain a new rating.
Exactly, that's why Airbus have three, it's logical......but wait it costs more money!

[wiedehopf]

Your Airbus if something fails is still operating within the approved envelope as per certification requirements and required testing/training.

If one of your AoA fail at take off, nothing changes - it fly's the same.


If it failed on 737 NG or Classic then you might have had continuous stick shaker which means you lose stall warning because it's already going off and no longer reliable.

That's not the "certified" state either and you haven't expressed concerns about it.
Having a third AoA sensor to fail functional with one failure is a feature the regulator could require from all transport aircraft built after date XYZ.
Would that improve safety? Maybe.

Still arguing that it's a non certified state is bogus.
When a system fails, some degradation can be declared acceptable.

[Pinkman]

1. Boeing management needs to develop a culture of accountability and get back its former culture of humility and engineering excellence with engineers at all levels of the organization. The MAX should only be built at Renton for the foreseeable future.

2. Address the issues at Charleston by unionizing and instituting a trust relationship between factory floor and management. Institute a mentoring program between sites to bring workforce skills, behaviours and product excellence up to par with other facilities.

Difficult? Yes. Impossible? No.

[Bend alot]

If it failed on 737 NG or Classic then you might have had continuous stick shaker which means you lose stall warning because it's already going off and no longer reliable.

That's not the "certified" state either and you haven't expressed concerns about it.
Having a third AoA sensor to fail functional with one failure is a feature the regulator could require from all transport aircraft built after date XYZ.
Would that improve safety? Maybe.

Still arguing that it's a non certified state is bogus.
When a system fails, some degradation can be declared acceptable.

The aircraft is certified if an AoA fails the stick shaker goes off, possible a requirement to get certification - the aircraft still operates the same regardless of where you are in the envelope.

The difference is in the MAX you get more than the stick shaker with an AoA failure you get a change of aircraft characteristics in certain areas. That change is "unknown in quantity" close to a stall and that change is known to be outside certifiable limits.

I expect it is very easy to get certification with a MCAS U/S, but I very much doubt it can be done without detailed training best done in the simulator - so there is a reduced startle factor with less experienced pilots.

Keep in mind where MCAS is actually required is in a small window of variable conditions and to NEED to be there, it is probably not a walk in the park day. So best not to have more surprises and start learning along the way when workload is already high.

Example - above 1,000 ft flaps up AP on - Birds! pull up, AP disengages miss birds, Another flock of birds again pull up in MCAS area now and it trims. You then trim to level as birds seem gone (MCAS deactivated) yet another flock of birds - pull back, this time the coulomb just comes right back aft into your crouch just like a cable has broken. Startle factor for more than a fraction of a second and it is in a stall, at best a few thousand feet AGL.

So you have just done two avoidance's in a B737, then third was in a fighter jet. Best to have some fighter jet training if that is what can happen.

[calypso]

An Airbus can be dispatched with one ADIR inop. Why such strong comments from people that know so little about how aircraft are certified or flown? Airbus has had its own significant issues with undesired control imputs due to faulty sensors, it is only a matter of luck that more of them did not crash.

Listen to what 737 is saying and you may learn something about how systems are designed, how we deal with failures before dispatch and how we deal with failures in flight. This is not Boeing specific. There are many many aircraft out there that are trickier to fly and have been flying for decades than a 737MAX.

Does this all mean that Boeing has nothing to learn from this? of course not but there are lesson here for Lion Air, ET, the FAA and pilots on general. Simplifying this into " the MAX is unsafe and is all Boeing´s fault" means missing many important lessons here.

From a statistical point of view a 737 MAX is way safer than your car, your bike, taking the bus, etc,etc,etc a take it that you are not rushing out to buy a a brand new car every six months so ease up on the hysteria chaps.

[cessnapete]

My sad prediction:

The next Max crash will involve a 3rd world airline without mature Western Airline training and experience with a crew so hyper vigilant about a MCAS runway that they will misdiagnose something else as a MCAS failure go to the stab cut out switches and now have to manually trim an out of trim aircraft, which is basically never done, get behind the airplane and fly it into the ground......


I had a Stickshake activate in the cruise at M.84 in a B747. Did we crash? No we evaluated the other flight parameters, disconnected the automatics for awhile, deactivating the false warnings and landed safely where the component was changed. Simples.

[Bend alot]

An Airbus can be dispatched with one ADIR inop. Why such strong comments from people that know so little about how aircraft are certified or flown? Airbus has had its own significant issues with undesired control imputs due to faulty sensors, it is only a matter of luck that more of them did not crash.

Listen to what 737 is saying and you may learn something about how systems are designed, how we deal with failures before dispatch and how we deal with failures in flight. This is not Boeing specific. There are many many aircraft out there that are trickier to fly and have been flying for decades than a 737MAX.

Does this all mean that Boeing has nothing to learn from this? of course not but there are lesson here for Lion Air, ET, the FAA and pilots on general. Simplifying this into " the MAX is unsafe and is all Boeing´s fault" means missing many important lessons here.

From a statistical point of view a 737 MAX is way safer than your car, your bike, taking the bus, etc,etc,etc a take it that you are not rushing out to buy a a brand new car every six months so ease up on the hysteria chaps.
I am not saying the MAX is unsafe even in version one.

Just saying it should have had better training, and now will still need better training.

But certification to be called Big Brother is pretty hard to claim without correct training under version 1 & 2 from what details have been released.

[PEI_3721]

The modified MCAS - https://www.boeing.com/commercial/737max/737-max-software-updates.page (17Apr - any later version) would only require two sensors to disable MCAS.
The acceptability of this depends the ease of flight for ‘abnormal conditions’ and the probability of occurrence. This should not be a problem, MCAS is only used in a small part of the flight envelope, not likely to be encountered often. However, given that previous 737s are sensitive to nose up pitch with high thrust - GA mode, then the acceptability of ‘abnormal’ flight in the 737 Max without MCAS might be more questionable.
Also consider the extent of the differences between the 737 Max and previous models - ‘it will be the same’, except for MCAS, etc. Are the normal flight handling qualities of the MAX sufficiently similar to previous aircraft - margin to certification limit - this is not the same judgement as ‘same type rating’.

The confidence in the modified design might be further questioned by the discovery of inoperative AoA Disagree elements in some aircraft. The effect of this depends on interpretation - either a simple pin program error (customer option), or a software error preventing the option from working, N.B. where - AoA Disagree is now a major aspect of the modification. https://finance.yahoo.com/news/boeing-737-max-8-software-update-205151888.html (In the ‘continued’ section)

The objective of the modification is to prevent large trim changes which could reduce the ability to fly the aircraft. If this is not assured, then MCAS would require much higher integrity - flight with MCAS disabled is judged unacceptable, or the software has insufficient integrity.
Then the system might require three vanes or alternative means of cross checking / use of sensors. Such integration will take time and may involve complex certification assessment given the history of events.

Re preflight vane checks; the validity of electrical connections might be checked, but not the accuracy of the AoA value, which like an aircraft requires the vane to be ‘flying’.

Re stick shake; AoA for Vsw is an alerting function - cross check with triple speed display.
AoA for MCAS is high-order safety action function - system disabling, no alternative.

[Cows getting bigger]

There’s another issue here.

MCAS will be solved and it appears BA are well on the way. However, there is little denying that they were somewhat disingenuous with it’s introduction and consequently their reputation & credibility has taken a hit. So, the question has to be what else slipped through the regulatory net? In other words, are there other things in the Max that customers have yet to discover?

If I had just bought a pile of Maxs at $100M a pop, I would want to get a warm feeling.

[Gertrude the Wombat]

Based on historical experience, the MAX will be certified to fly again, there will be some initial public avoidance, but after a year (maybe less) most passengers will get over their qualms
I'm not flying in one.

And nobody has answered the following question (in any forum I've asked it): Are there any other unstable airliners out there which I may wish to avoid?

[L337]

I'm not flying in one.

And nobody has answered the following question (in any forum I've asked it): Are there any other unstable airliners out there which I may wish to avoid?

The words "unstable airliners" is meaningless. What do you mean by "unstable?"

Trying to guess your intent. In general terms every airliner is unstable at the limit. Push hard enough it will depart. However, at the edge of the envelope, it needs to be predictable. So to answer the question I think you are asking, is... Yes. All airliners are unstable. Avoid all airliners.

[Bend alot]

The modified MCAS - https://www.boeing.com/commercial/737max/737-max-software-updates.page (17Apr - any later version) would only require two sensors to disable MCAS.
The acceptability of this depends the ease of flight for ‘abnormal conditions’ and the probability of occurrence. This should not be a problem, MCAS is only used in a small part of the flight envelope, not likely to be encountered often. However, given that previous 737s are sensitive to nose up pitch with high thrust - GA mode, then the acceptability of ‘abnormal’ flight in the 737 Max without MCAS might be more questionable.
Also consider the extent of the differences between the 737 Max and previous models - ‘it will be the same’, except for MCAS, etc. Are the normal flight handling qualities of the MAX sufficiently similar to previous aircraft - margin to certification limit - this is not the same judgement as ‘same type rating’.

The confidence in the modified design might be further questioned by the discovery of inoperative AoA Disagree elements in some aircraft. The effect of this depends on interpretation - either a simple pin program error (customer option), or a software error preventing the option from working, N.B. where - AoA Disagree is now a major aspect of the modification. https://finance.yahoo.com/news/boeing-737-max-8-software-update-205151888.html (In the ‘continued’ section)

The objective of the modification is to prevent large trim changes which could reduce the ability to fly the aircraft. If this is not assured, then MCAS would require much higher integrity - flight with MCAS disabled is judged unacceptable, or the software has insufficient integrity.
Then the system might require three vanes or alternative means of cross checking / use of sensors. Such integration will take time and may involve complex certification assessment given the history of events.

Re preflight vane checks; the validity of electrical connections might be checked, but not the accuracy of the AoA value, which like an aircraft requires the vane to be ‘flying’.

Re stick shake; AoA for Vsw is an alerting function - cross check with triple speed display.
AoA for MCAS is high-order safety action function - system disabling, no alternative.


Yes but also needs to be noted is a issue known even with the NG and prior, is the ineffectiveness of the trim wheel under some conditions. actually "ineffective" is an understatement.

Does MCAS have or can have an effect on this well known manual trim deficiency?

[EIFFS]

The aircraft is certified if an AoA fails the stick shaker goes off, possible a requirement to get certification - the aircraft still operates the same regardless of where you are in the envelope.

The difference is in the MAX you get more than the stick shaker with an AoA failure you get a change of aircraft characteristics in certain areas. That change is "unknown in quantity" close to a stall and that change is known to be outside certifiable limits.

I expect it is very easy to get certification with a MCAS U/S, but I very much doubt it can be done without detailed training best done in the simulator - so there is a reduced startle factor with less experienced pilots.

Keep in mind where MCAS is actually required is in a small window of variable conditions and to NEED to be there, it is probably not a walk in the park day. So best not to have more surprises and start learning along the way when workload is already high.

Example - above 1,000 ft flaps up AP on - Birds! pull up, AP disengages miss birds, Another flock of birds again pull up in MCAS area now and it trims. You then trim to level as birds seem gone (MCAS deactivated) yet another flock of birds - pull back, this time the coulomb just comes right back aft into your crouch just like a cable has broken. Startle factor for more than a fraction of a second and it is in a stall, at best a few thousand feet AGL.

So you have just done two avoidance's in a B737, then third was in a fighter jet. Best to have some fighter jet training if that is what can happen.

Even if the MCAS was disabled the STS would still be operational and this works to increase column force required in the event of a high pitch up at low speed.

once the MCAS is disabled any erroneous data can be eliminated using memory items followed by check lists for unreliable airspeed, AP off AT off F/D off pitch either 10-80% with flaps extended ( in this instance MCAS is not active anyway) or 4-75% clean, if MCAS has been disabled due to erroneous signals then at 4 degrees NUA and 75% you are going nowhere near the stall environment, moreover you are in control and not some sub system putting in NDA stab inputs, of course the system has to ensure controlled flight in all phases of flight, the only problem is that we know that at full column deflection the airflow load over the stab can exceed the electric or manual trim capability and Boeing recommends reducing these loads by momentarily releasing back or forward pressure and using the electrical or manual trim, not so easy to do this when you are hurtling towards the ground.

what we really need to know is why these aircraft had erroneous data in the first instance, was this a build fault, manufacturing fault, poor system maintainance, bird strike or other?

Ive been flying the Classic, NG & MAX since 2005 through to a week before it’s grounding and have never once needed to use the trim cut out switches, the MAX is a beautiful bit of kit to fly albeit with a now discovered fatal flaw.

Just how we rebuild passenger trust is going to be a real challenge especially if like us we have mixed fleet where we might be rostered an NG and then for operational requirements change to the MAX.

Even now given the publicity surrounding the MAX grounding we have a number of passengers on nearly every flight asking if this is a MAX, not helped by the fact that the briefing card says 737-8/ MAX, I think many people will either avoid airlines flying the 737 MAX or avoid Boeing aircraft, then of course every time there is an incident involving a 737 ( MAX or otherwise) the media spotlight will focus again on MCAS.

If i were Boeing I would be starting design on a clean sheet replacement for the 737 rather than the middle of the market replacement. I have total faith that Boeing will get this right? maybe continue with NG production along side the MAX giving customers an option at a heavily discounted price.

They are probably going to have to discount the MAX unit price in any event.

[safetypee]

Cows,
‘… what else slipped through the regulatory net? ‘

Like the inability to recover the aircraft after a trim runaway - this is not changed by MCAS cutout - problem as per Bend alot #64. Reduced confidence in the procedure after the accidents and sim demo. The drill depending on pilot recognition and timely action, and a complicated ‘yo-yo’ manoeuvre.
This relates to an industry wide question of how much credit can be taken for human involvement in rare or surprising situations. Then the insolvable debate about training; those who can, those who can’t, and those who think they can, but do not perform at the critical time because the situation is not recognised or too difficult (where’s the ‘trim fail’ light).

Another ‘slip’ is the AoA display on EFIS. With AoA failure the gauge displays may not be removed, crews cannot determine which one is accurate - hazardous misleading information.
Also, why have a separate AoA display when the same information is shown overlaying the EFIS speed scale, that scale is associated with more meaningful dual cross-monitoring IAS (ADC) Disagree alert.
Unnecessary display clutter.

[ManaAdaSystem]

I have to say that if I got a stick shaker after takeoff, my first thought would not be «I have a faulty AOA sensor».
I would think stall and configuration. I would lower the nose to increase speed. Then start to find out what was going on.
And if my aircraft did not have the AOA disagree caution installed, AOA sensors may or may not be on my list of causes for the stick shaker. A SMYD failure would be more likely since I have never had a AOA failure on the NG in the 20 years I have been flying it. I don’t understand why it fails when it’s installed on the MAX?
This is a response to 737 Drivers claim that AOA sensor failure would be on the top of the list when a stick shaker goes off after takeoff.

[Deepinsider]

One pilot joins up just last month, and then makes over 200 posts, leaving no doubt
at all that he/she thinks the plane is fine and the pilots are not up to it.
One guess,,, which city this pilot is based! I wonder who his/her employer might be?
Was there talk that Russia used social media to influence an election? Could this be
a home grown equivalent?

[PEI_3721]

EIFFS,
MCAS / STS, interesting points, and other aspects agreed :ok:
The ‘use’ of STS questions why it was not used in the first instance: - speculation, that the particular stability deficiency was AoA / manoeuvre related and thus not manageable with speed. Is STS applicable flaps up.
What more might this indicate about the extent of the aerodynamic problems, albeit in a small part of the flight envelope.

General question; does the Max have the two-stage (double press) TOGA selection, which is related to pitch attitude/rate; is GA /TOGA available with flaps up, and if without MCAS would the pitch-up be excessive (N.B. several incidents in NG).

Bend alot,
… ineffectiveness of the trim wheel under some conditions, actually "ineffective" is an understatement.
As noted by EIFFS, this is a serious problem to add to the recertification discussions.

[marchino61]

One pilot joins up just last month, and then makes over 200 posts, leaving no doubt
at all that he/she thinks the plane is fine and the pilots are not up to it.
One guess,,, which city this pilot is based! I wonder who his/her employer might be?
Was there talk that Russia used social media to influence an election? Could this be
a home grown equivalent?

Well spotted!

[ManaAdaSystem]

One pilot joins up just last month, and then makes over 200 posts, leaving no doubt
at all that he/she thinks the plane is fine and the pilots are not up to it.
One guess,,, which city this pilot is based! I wonder who his/her employer might be?
Was there talk that Russia used social media to influence an election? Could this be
a home grown equivalent?

The tought has crossed my mind. He is also very well informed about all new developments and fixes.

[Cows getting bigger]

Chaps, let’s play the ball not the man.

[737 Driver]

MCAS has no redundancy, and if there is a failure of MCAS the flight characteristics do change in certain areas of the envelope. You just will not know how abruptly or placid this change might be until you find yourself there (that may never happen just like an engine failure after take-off) or even amount of change v/s speed. What is the difference in a turn? will it try roll you also?



MCAS/STS has two independent channels, so it does have redundancy. I think you may be referring to the fact that the loss of AOA will keep MCAS from activating. The loss of MCAS will not cause the aircraft to fall from the sky. Loss of MCAS will only change the handling characteristics approaching a stall. Most aircraft never, ever get near the stall regime in normal operations.

[737 Driver]

This is a response to 737 Drivers claim that AOA sensor failure would be on the top of the list when a stick shaker goes off after takeoff.

Sorry if I gave that impression. This aspect was covered extensively in the other thread. What I said was if the stick shaker was going off and the aircraft was accelerating and climbing normally (i.e. obviously not stalling), then that would be a clear indication of an AOA issue.

[Bend alot]

Well spotted!
A few of us are around 200 posts - again!

Happens more on the rumours section than other areas.

[737 Driver]

General question; does the Max have the two-stage (double press) TOGA selection, which is related to pitch attitude/rate; is GA /TOGA available with flaps up, and if without MCAS would the pitch-up be excessive (N.B. several incidents in NG).


One press of the TOGA buttons will produce a 1000-2000 fpm rate of climb. A second press will advance the engines to full G/A power. MCAS only operates with the flaps retracted, so it would not be a factor during the initial G/A sequence (which is where one would have any issues with the power/pitch coupling).

[groundbum]

except the man is playing all of us, and not the ball! He could declare his interest in all this, and state he has no relationship with big B of any kind..

G

[737 Driver]

The tought has crossed my mind. He is also very well informed about all new developments and fixes.

Well, I do actually fly this aircraft ........ Guilty as charged!

[737 Driver]

except the man is playing all of us, and not the ball! He could declare his interest in all this, and state he has no relationship with big B of any kind..



Okay folks, getting a little paranoid here, but no I do not have any relationship with Boeing except for the facts that I have flown their aircraft for over 30 years. That should take care of any concerns, right? ;)

[Bend alot]

MCAS/STS has two independent channels, so it does have redundancy. I think you may be referring to the fact that the loss of AOA will keep MCAS from activating. The loss of MCAS will not cause the aircraft to fall from the sky. Loss of MCAS will only change the handling characteristics approaching a stall. Most aircraft never, ever get near the stall regime in normal operations.
Yep, all redundancy except till the AoA's then a single point failure. So is there no need for you to know the change in handling even if it is severe?

[PEI_3721]

The preceding thread on 737 Max future has been closed, presumably due to inappropriate posts - play the ball, not the person.
Closure appears to be an excessive reaction to a problem which could be managed by other means; as a result the interesting theme being discussed - 737 Max future, return to service, recertification, has been stifled.
Thus, in continuation: ‘737 Max MCAS recertification and return to service’.

[PEI_3721]

737 Driver,
Thanks for the info on TOGA, previous thread.
You overlooked my speculative ‘if’ - ‘if without MCAS could the pitch-up be excessive’.

The primary reason for two-stage TOGA was to reduce / manage the rate of pitch-up and/or excessive attitude during GA, which could reduce the stall speed margins. First press gives GA, vertical speed demand, second press is an ‘open climb’ demand with speed protection for max vertical rate in terrain limiting situations.
The NG has had problems in this area, the assumption is that the Max is similar or worse, particularly with MCAS unavailable (flaps-up ‘GA’). This in these circumstances it would be very important that the crew were aware of inoperative MCAS.

Previously you cited a recent MCAS briefing, was this on the same information as in the Boeing link https://www.boeing.com/commercial/737max/737-max-software-updates.page, or some new views which might have been resubmitted to the FAA.

Re redundancy; single AoA has been the prime focus, but with additional software there are opportunities for new failure paths.
Dual systems degrade are accepted within limits, e.g. single FGC approach, but not Cat 3, the extent of any failure is bounded.
The potential effect of MCAS computational malfunction might not have similar bounding safety limits - other than pilot recognition and intervention. Which of course has been shown to be ineffective, perhaps more so if with dual AoA into MCAS, the rare ‘never saw this before’ creates even greater surprise and mental demand.

Most of the aspects above relate to the nature of the failure - input, vane, vane unit, wiring, digital conversion, or software computation, all of which are unknown (publicly).
Repeating previous comments - can any modified system be approved, risks assessed, if the initiating problem is unknown or unrepeatable.

[Smythe]

Seattle Times reporting that Boeing changed the function of the stab trim switches on the MAX vs NG. (does not appear to have told anyone)
https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/850x567/vrjcta1_fa21f5d971ca035abd21c1a04d9145fa6683daec.jpg
https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/420x236/pv6gk1u_8c364fef6cd6a0fefacf906351e53f20e255707c.jpg

[Pilot DAR]

Thus, in continuation: ‘737 Max MCAS recertification and return to service’.

Yes, we can have a thread about the 737 Max return to service. We don't need multiple threads on the same theme, people won't know where to read nor post.

So this is it! Discussion on the return to revenue service of the Boeing 737 Max 8/9....

[JanetFlight]

Interesting link here despite all MAX frenzy...

https://www.fool.com/investing/2019/04/13/boeing-crushes-airbus-q1-aircraft-orders-737-max.aspx

[YYZjim]

Dear Mr. 737 Driver:

It looks to me like some posters on this forum have decided that you are employed by [redacted] and are spreading bad thoughts. I don't think that, and I appreciate the information in your posts. One of your posts yesterday sounded a lot like the kind of briefing MAX line pilots are starting to get about the upcoming fix. I would sure like to hear more.

To overcome the grief you're getting from some posters, you might consider sending a private message to a long-time poster (David Reid UK or gums, for example) and inviting them to act as your WikiLeaks.

YYZjim

[BluSdUp]

I appreciate You taking it upon Yourself educating us all from Your unique standpoint as an experienced 737 driver.
What You fail to see is that You and not so few 737 "drivers" are not in the game on this one, as there is a tendency to fully understand a rather ancient and outdated system.
It is up to the young and smart magenta-line N-CAA Inspectors and Regulators to be 110% happy with what FAA and Boeing have done in the Certification process and RE-Certification process.
THEN, if GO is the answer:after how many Sim maneuvers required.
And to be honest , they are doing Boeing and FAA a favor.
For, if there is a MCAS/ STS or Stall incident or accident it is all over.
It is not so much a technical/aerodynamic challenge as it is a Human factors CRM issue.
As You , I love the Old Girl, but she is ugly and she does bite.
Bit of a handfull for the young cadre, me thinks.

Just for the record:
Never in Aviation History have we had such a mess:
1 AOA failing on new aircraft.

2 AOA feeding incredible crude deadly system without redundancy ( NO Pilots are NOT part of System Redundancy, Sir!)

3 FAA total lack of involvement.

No accident has this combination, ever.

(4 A possible lack of will to understand and admit fault by Manufacturer.)

Regards
Cpt B

[737 Driver]

One of your posts yesterday sounded a lot like the kind of briefing MAX line pilots are starting to get about the upcoming fix. I would sure like to hear more.

While there was some more detail in the brief, it was "inside baseball" type material and probably would not mean much unless you were a [redacted] operator.

To overcome the grief you're getting from some posters, you might consider sending a private message to a long-time poster (David Reid UK or gums, for example) and inviting them to act as your WikiLeaks.



Well, beside the lag time problem, I think the idea of using someone else as cover creates its own host of ethical issues. Much of what I do here is simply report how things actually work to correct the misconceptions of how some posters think they work. People can critique [redacted] all they want, but if they have a fundamental misunderstanding of the aircraft, systems or procedures, they shouldn't expect a receptive audience among those who do have a ready grasp of the material.

[edmundronald]

In this operator's opinion, certainly not shared by all, the "AOA Disagree" alert that has captured so much attention is not that bid of a deal. If the AOA's are really that far apart, there will be sufficient other indications because of how the AOA information is integrated into other aircraft systems. In the case of both Lion Air flights and ET302, an active stick shaker while the aircraft is accelerating and climbing normally is the big, annoying, and very obvious indication that something is amiss with your AOA system - and that becomes active as soon as the aircraft lifts off the ground

SLF, PhD, engineer here:

Are 737 Max crews going to learn to respond to that "Special AoA stick shaker" via an iPad briefing? Because it appears simulator training for the Max pilots is excluded ...and I believe pilots are educated to know that stick shaker usually means low speed or stall, so now the stick shake signal is ambiguously getting overloaded with a second semantic.

Also don't you pilots think that having the stick shaker go off quite soon after you clean up and are accelerating (!) is a bit confusing at a moment of fairly high workload, and resolving the semantic ambiguity - AM IS STALLING OR IS THIS JUST AoA DISAGREE? - carries with it a non-negligible chance of startle factor, non-optimal pilot response, and then PIO or even as in the case of two Max airframes uncontrolled flight into terrain and grief issues for a number of families?

Is this fix really a fix without sim training?

Can one really say that with this fix the Max is sufficiently identical in behavior to the NG that neither the pilot training nor the type certificates require updates?

Edmund

On reflection, rather than making an ass of myself talking about stuff I don't know, I think from now on I'll watch this from the sidelines.

[wiedehopf]

AM IS STALLING OR IS THIS JUST AoA DISAGREE? - carries with it a chance of startle factor, non-optimal response, and then PIO or even as in the case of two Max airframes uncontrolled flight into terrain?

Is this fix really a fix without sim training?

Can one really say that with this fix the Max is sufficiently identical in behavior to the NG that neither the pilot training nor the type certificates require updates?


The stick shaker behaves the same way no matter NG or MAX.

[b1lanc]

Well, I do actually fly this aircraft ........ Guilty as charged!

And I do hope you are up front on my next Max flight.

[737 Driver]

SLF, PhD, engineer here:

Are 737 Max crews going to learn to respond to that "Special AoA stick shaker" via an iPad briefing? Because it appears simulator training for the Max pilots is excluded ...and I believe pilots are educated to know that stick shaker usually means low speed or stall, so now the stick shake signal is ambiguously getting overloaded with a second semantic.

Also don't you pilots think that having the stick shaker go off quite soon after you clean up and are accelerating (!) is a bit confusing at a moment of fairly high workload, and resolving the semantic ambiguity - AM IS STALLING OR IS THIS JUST AoA DISAGREE? - carries with it a non-negligible chance of startle factor, non-optimal pilot response, and then PIO or even as in the case of two Max airframes uncontrolled flight into terrain and grief issues for a number of families?



In terms of the thought process that the 737 pilot goes through to determine whether a stick shaker warning is either 1) correct thus requiring stall avoidance procedures, or 2) false thus requiring faulty AOA or airspeed input procedures (i.e. Airspeed Unreliable NNC), the 737NG and MAX are absolutely identical and no difference training is needed. This thought/decision process should occur very quickly, even accounting for the startle effect.

If you can figure this out in the NG, you can figure it out in the MAX. The corollary is, however, if you can't figure it out in an NG, you are not going to figure it out in the MAX either.

[737 Driver]

Question - how much altitude is lost when using manual trim wheel to crank back to the trim value in use when the flaps go up, Hal goes wild, to its max amount and pilot shuts of either or both primary and b/u switches immediately. Can it be done by ONE pilot or does it take two ?

Yes, I knows it is speed dependent as to required force to spin wheel ( nose up ) depending on which way failure is ..

Hopefully, the answer is zero. There will probably be some up and down on the altitude as the aircraft is stabilized, but if the pilots correctly apply the runaway stab procedure then there should be no significant loss of altitude. (From the data released to date, it appears the Lion Air 610 accident pilots did not accomplish this procedure, and the ET302 pilots did not accomplish the procedure correctly).

While the procedure itself can be accomplished by one pilot, every procedure on the 737 (normal and non-normal) is designed to be accomplished as a crew to ensure that it is done correctly. If the stab is significantly out of trim when the electric trim is cutout, it will likely require the efforts of both pilots to use the manual trim to return the aircraft to a neutral trim state.

[737 Driver]

.
Seattle Times reporting that Boeing changed the function of the stab trim switches on the MAX vs NG. (does not appear to have told anyone)
.

.
Yes on the first part (covered extensively in previous threads). No on the second part - the change in labeling and function was disclosed in the FCOM. The changes did not include a detailed wiring diagram, but one was not needed either.

Seattle Times article can be found here: link (https://www.seattletimes.com/business/boeing-aerospace/boeing-altered-key-switches-in-737-max-cockpit-limiting-ability-to-shut-off-mcas/)​​​​​​

Also covered extensively in previous threads, the change in functionality made no difference procedurally. The 737NG and the MAX runaway stab procedure calls for the use of both switches. I had speculated previously that the two switches were retained on the MAX, in part, to provide commonality with the NG. The article above has this statement from a Boeing spokesperson:

. (https://www.seattletimes.com/business/boeing-aerospace/boeing-altered-key-switches-in-737-max-cockpit-limiting-ability-to-shut-off-mcas/)
​​​​​​ (https://www.seattletimes.com/business/boeing-aerospace/boeing-altered-key-switches-in-737-max-cockpit-limiting-ability-to-shut-off-mcas/)Boeing said in a statement that the company had historically called for pilots to flip both switches to shut of a problematic or “runaway” stabilizer, so the change on the MAX ensured that the function of the switches matched that procedure. The company said the two switches “were retained for commonality of the crew interface.”
.


So it appears that speculation was correct.

[BluSdUp]

The Amsterdam seminar for Max customers on Tuesday had limited information and time lines to offer.
EASA is talking late summer.
Was covered on a closed thread.

Regards
Cpt B