They do have experience of mile-high Denver, though.

One comment on the US pilots' report - was that 10k ft AGL or 10k ft ASL?
This is very important because Addis Abba's airport is at about 7.5k ft ASL, and there will be a difference in the way the plane controls at 14k ft ASL compared to 7k ft ASL......

Reading the report, it isn't clear, but if the test was set up specifically for Addis Abba, then I'd expect 10K + Addis Abba ASL. Also not clear is if the pilots in the simulation reduced thrust. Afterwards they recommended that as a recovery aid in addition to the procedure they used.

Also this report seems to indicate another issue, that the manual trim wheel doesn't have enough mechanical leverage to operate in all flight conditions. That would be across ALL 737's, not just MAX's.

Finally this wasn't a test of MCAS, but a runaway trim and recovery.

Pretty damning if true.

Article in NYT titled "Boeing Built Deadly Assumptions Into 737 Max, Blind to a Late Design Change"

SEATTLE — The fatal flaws with Boeing’s 737 Max can be traced to a breakdown late in the plane’s development, when test pilots, engineers and regulators were left in the dark about a fundamental overhaul to an automated system that would ultimately play a role in two crashes.

A year before the plane was finished, Boeing made the system more aggressive and riskier. While the original version relied on data from at least two types of sensors, the ultimate used just one, leaving the system without a critical safeguard. In both doomed flights, pilots struggled as a single damaged sensor sent the planes into irrecoverable nose-dives within minutes, killing 346 people and prompting regulators around the world to ground the Max.

But many people involved in building, testing and approving the system, known as MCAS, said they hadn’t fully understood the changes. Current and former employees at Boeing and the Federal Aviation Administration who spoke with The New York Times said they had assumed the system relied on more sensors and would rarely, if ever, activate. Based on those misguided assumptions, many made critical decisions, affecting design, certification and training.

“It doesn’t make any sense,” said a former test pilot who worked on the Max. “I wish I had the full story.”

There it is laid bare. A software documentation flaw. The software was changed, the documentation wasn't. An IT fault -- and a very common one throughout the IT world -- Who FU'd the version control system? Or did they even have one?

Of course that still doesn't excuse the failed AoA sensor or how the F the maintenance crew didn't repair it when the previous flight it had been called out as failed. (Is a failed AoA sensor a nogo in the minimum equipment list? With MCAS onboard it should be.)

I expect out of this that there will be an AD requiring the software to be locked down before certification flight testing in the future so that any differences between the flight manual and the software will become apparent when the certification flights are flown. I might also expect an AD requiring testing of all AoA sensors of a similar design at a specified flight hours interval and a specific test method, not just a visual looks good.

There it is laid bare. A software documentation flaw. The software was changed, the documentation wasn't. An IT fault -- and a very common one throughout the IT world -- Who FU'd the version control system? Or did they even have one?

Hasn't it sunk it yet? So it may be am issue with the software. So what? THAT wasn't the root cause. This was:

MCAS was introduced by Boeing on the 737 Max 8 because its heavier, more fuel-efficient engines changed the aerodynamic qualities of the workhorse aircraft and can cause the plane's nose to pitch up in certain conditions during manual flight.

The underlying root of MCAS was this:

In March 2010, the estimated cost to re-engine the 737 according to Mike Bair, Boeing Commercial Airplanes' vice president of business strategy & marketing, would be $2–3 billion including the CFM engine development. During Boeing's Q2 2011 earnings call, former CFO James Bell said the development cost for the airframe only would be 10–15% of the cost of a new program estimated at $10–12 billion at the time. Bernstein Research predicted in January 2012 that this cost would be twice that of the Airbus A320neo.

Therefore the ROOT CAUSE was...

...Profits 1st

Fuel consumption is reduced by 14% from the 737NG.

Blame the bean counters!

Sorry Sirius. The root cause is an IT fault. Or why aren't we all still using Z-80's on CP/M? If you want to say profit, then you need to blame THE AIRLINES for wanting a cheaper to run airplane, and that isn't Boeing's bottom line.

OBW https://en.wikipedia.org/wiki/BAC_One-Eleven had its own version of MCAS. https://en.wikipedia.org/wiki/1963_BAC_One-Eleven_test_crash This was 1963. It isn't a new idea. Boeing called it "MCAS" not "Stick Pusher."

It's an IT fault in that sense the MCAS system obviously not was communicated to so many pilots.
So both Boeing and the airlines are to blame.
There is difference between training and learning how to fly a plane.
Explained in this video and also some more.
https://www.youtube.com/watch?v=CD0JabYjF3A&feature=youtu.be&t=88

I take it that you have a considerable investment in Boeing, considering how far you're going to defend them. No one is excluding either the FAA or the airlines on their culpability on this thread (at least I can see).
The problem is that they have been some very good posts so far that have highlighted warning signs that were ignored.
1: The design had reached its sell by date.
2: Bigger & more efficient engines altering the aerodynamics.
3: Company "fudge" to avoid type certification.
4: Software/Flight manual errors.
All down to Boeing.
1: Any successful design can only endure a certain amount of changes/upgrades before it becomes problematic.
2: Fuel efficiency is good. However Forcing re-positioning of engines changes the aerodynamics which creates its own problems.
3: Well, that speaks for itself.
4: Boeing were aware of the software issue in 2017 & their answer was:

the existing functionality was acceptable until the alert and the indicator could be delinked in the next planned display system software update.

In March 2010, the estimated cost to re-engine the 737 according to Mike Bair, Boeing Commercial Airplanes' vice president of business strategy & marketing, would be $2–3 billion including the CFM engine development. During Boeing's Q2 2011 earnings call, former CFO James Bell said the development cost for the airframe only would be 10–15% of the cost of a new program estimated at $10–12 billion at the time.

Hmm, 2nd Q 2011, a new program is estimated at $10-12 billion. Wonder what THAT cost would be in 2030?

In November 2014, Boeing Chief Executive Officer Jim McNerney said the 737 will be replaced by a new airplane by 2030, slightly bigger and with new engines but keeping its general configuration, probably a composite airplane.

At least someone in Boeing realises a new design is required.
Source 1
Source 2

Also, if I read source 1 correctly, Boeing did not create the software:

In 2017, within several months after beginning 737 MAX deliveries, engineers at Boeing identified that the 737 MAX display system software did not correctly meet the AOA Disagree alert requirements. The software delivered to Boeing linked the AOA Disagree alert to the AOA indicator, which is an optional feature on the MAX and the NG. Accordingly, the software activated the AOA Disagree alert only if an airline opted for the AOA indicator.

AND did nothing until November 2018 as it did not constitute a safety issue. THAT is not down to the software company but Boeing!

Sorry this is a SYSTEM failure.
The problem is that systematically information was not channelled forward to the user of the data.
The HARDWARE guys decided to change the sensors.
The SOFTWARE guys (NOT "IT") made a change in the software to accommodate this HARDWARE change.
The RAMS guys didn't assimilate the HARDWARE and SOFTWARE changes into their models.
The MANUAL WRITERS were in the dark, they didn't have all the relevant information about a system they didn't know about.
The APPROVERS didn't fully understand the the implications of the combined HARDWARE and SOFTWARE changes.
The FINANCIAL guys rubbed their hands at the saving the HARDWARE guys had achieved by simplifying the system.
PROJECT MANAGERS shouted with glee as delivery dates were met.
MANAGEMENT just let things roll on.
SHARE HOLDERS were happy was because Boeing now had a plane to face off with the Airbus A320x family.
SALES STAFF were only told the "good stuff", as technically there was no "bad stuff".
AIRLINES were happy because they had a new plane they could put into service without massive training costs (hey, what does an hour of looking at an i-pad cast?)

The along came "real pilots" who did the training using the i-pad application and flights started.
Then there were "random" reports of strange things happening.
Then planes fell out of the sky......

BOEING are totally in the frame form day-zero. It's pointless blaming anyone else:
BOEING hardware engineers changed the sensors;
BOEING software engineers did the software changes;
BOEING RAMS engineers overlooked some key impacts of these changes
- This led to BOING test staff not being aware of the possible adverse impacts of the changes.
The FAA were not aware of the impact as they didn't know about it (ah, we've finally got to someone outside BOEING....)
Meanwhile BOEING financial guys, BOEING project mangers, BOEING share holders, BOEING sales staff were very much in the dark as to the hidden technical "challenges".
The airlines just read the sales blurb, and ordered as they saw the B373MAX as a good fit with their existing, ageing fleets.

Ah - I forgotten about the BAC-111 with its stall prevention system over-reacting and causing a crash back in the 1960s.... That system was intended to be a "Stall Prevention System" - the reason was that the BAC-111 was prone to premature engine and aerodynamic stalls, so a system was required to prevent it. Unlike MCAS which is intended to be a "pilot aid" and assist the pilot from entering the "stall danger zone", not to prevent a stall. (If anyone can explain what the difference between a "pilot aid to prevent a stall" and a "system to prevent a stall" is.....
I would also add that there are many other airliners around with "MCAS-Like" systems - most of the A320 family, most of the "T-Tail" aircraft, and no doubt quite a few more.

It is also worth remembering that the B737 is not "inherently unstable", and can be flown "quite happily" with MCAS disabled, just with a higher pilot wok load at certain flight phases - notably during post-take-off climb out, where air speeds tend to be lower and angle of attack potentally higher.

---

Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

After all that "truth", I would not be at all surprised if Airlines "slack" maintenance got the blame even though it highlighted said truths.
With the way the aircraft industry is going, I personally think it best to return to a 3 person flight crew. Pilot, Co-pilot & Flight Engineer. Never going to happen though as the bean counters would scream bloody murder.
Edit. Again referring to source 1, if MCAS is to be delinked from the AoA, what is the actually point of MCAS?

Again referring to source 1, if MCAS is to be delinked from the AoA, what is the actually point of MCAS?

To prevent some dolt who fire-walls the throttles on climb out from entering aerodynamic stall. It is a stick pusher just like on dozens of other aircraft models going back to 1963.

BTW "IT" is Information Technology, it isn't Internet Technology.

The Information that a change was made to code failed to get propagated. That is an IT failure.
Alternately the Information that the code was locked down and should not be changed didn't get to the coders. That is an IT failure.
You Pick. Either case it is a system failure of Information. You have heard of a CIO? Chief Information Officer.

None of that however addresses why the AoA sensor failed. Or do you want to forget that Boeing doesn't make that part?

Can you point to any report that MCAS does anything wrong as long as it isn't getting garbage input from failed parts?

BTW if the ground crew loads the airplane nose heavy or tail heavy it is far worse than the movement of the engines forward or extra thrust.

Can you tell anyone with a straight face that if the AoA sensor hadn't failed there would have been a crash? Are you going to blame Boeing for a part they don't make?

Oh, unless there is some Boeing in a mutual fund, I don't own any.

I just want everything fixed so it doesn't happen again a year later perhaps not even on a Boeing airplane.

Or do you want to forget that Boeing doesn't make that part?
Are you going to blame Boeing for a part they don't make?

YES they are to blame. Err Gary, who built the aircraft? Fred Flintstone CEO of Dropit & Run?

In the case of the Lion Air crash there where 3 pilots in the cockpit.
He was off duty but apparently he helped the crew to crank the trim wheels trying to manually adjust the horizontal stabilizer.
You need a lot of muscle power to turn those wheels when the plane speed up...
But then you don't need a extra pilot to do that.
https://www.thehindu.com/news/international/third-pilot-was-in-the-cockpit-of-lion-air-that-crashed-in-october/article26598235.ece

Or do you want to forget that Boeing doesn't make that part?
Are you going to blame Boeing for a part they don't make?

YES they are to blame. Err Gary, who built the aircraft? Fred Flintstone CEO of Dropit & Run?

Okay. So when an Airbus with a sensor made by the same company crashes, it will be Boeing's fault. Got it.

https://www.stuff.co.nz/travel/travel-troubles/99660315/photos-air-nzs-damaged-787-engine
Rolls Royce engine, but Boeing's fault. Got it.

Now you're being totally silly. Regardless of who manufactured the part, it is down to the aircraft builder to ensure that every part works as it should, test fly it, get its airworthiness & type certifications before being passed to the customer.
What the customer does then is down to them not the builder.
Has those points sunk in yet?

None of that however addresses why the AoA sensor failed. Or do you want to forget that Boeing doesn't make that part.

Hmm... Why doesn't the 737MAX take input from both of the two sensors installed and not having a system that warn pilots that something is wrong?

Ever heard of Murphy's Law?

And there are many that have addressed why the AoA sensor failed.
Collision with a bird. Airports at a high altitude. Warm air.

Or more importantly, a fatal design flaw. WHY does disabling MCAS also disable another essential flight control - Electrical power to trim controls? Do the manufacturer of those controls get the blame?

From what I can understand the pilot need a motor to adjust the stabilizer in these circumstances.
Why doesn't the MCAS stop when disengaged by the pilot so he/she can take control over the plane?

Regardless of who manufactured the part, it is down to the aircraft builder to ensure that every part works as it should, test fly it, get its airworthiness & type certifications before being passed to the customer.

Actually no. But that is because you don't realize that in the case of many parts on the airplane it is the manufacturer of the part who has to get it certified as airworthy, because he is selling it to many different companies who build planes.
The plane builder has to make sure it integrates to the air-frame. Are you suggesting Boeing did not test the AoA? They would have had to calibrate the AoA to the air-frame so of course they tested it.

Does the plane manufacturer have to test every bolt? No! He specifies a bolt of a particular strength. The maker of the bolt has to certify his bolt meets those specifications. When it doesn't all hell breaks loose.
For instance https://www.cnn.com/2019/06/02/business/boeing-faa-737-slat-track-assemblies/index.html
Just like a Takata air bag.
Paperwork saying it is as specified. But it isn't!

There needs to be a focus on the AoA sensor. Why did it fail? Did the manufacturer of the AoA sensor use sub-standard parts? Is it because the 737-MAX vibrates in some unique way compared to the other aircraft the sensor is on? Is there some fault in the electrical system that is causing the premature aging of the sensor? Did some ground crew bump it and damage it? Is the pre-flight test not catching failed sensors? Why did it fail?

I suspect you want to scream MCAS because we all know it is easy to blame computer software and then you can wash your hands of the matter. MCAS failure was it not recognizing the garbage input, well, tell me again about the AoA sensor? What is its MTBF? Otherwise it did exactly what it was supposed to do, prevent an aerodynamic stall.

The software documentations system, IT, blew up. Understanding that is another cause investigation.