Alaska Airlines flight forced to make an emergency landing (Part II)... 26

[3DDave]

"Southwest Airlines Pilot Association" " A runaway stabilizer has continuous un-commanded movement of the tail"

Already dealt with. All trim runaway stops when the jack screw hits the stops, therefore there cannot ever be runaway because the movement is not continuous, per this definition.

"MCAS disables the control column response that 737 pilots have grown accustomed to "

That response is intermittent. As soon as force is relieved the trim will run again.

Anyway, it's a legal complaint, not an engineering or other assessment. It's goal is to convince uneducated people on a jury, not present truth.

"The EASA certification document referred to simulations whereby the electric thumb switches were ineffective to properly trim the MAX under certain conditions."

Always good to leave out what problem they are talking about.

"Also reading the wiki I hadn't realised that the screw jack was slipping due to the control force in both accidents."

What "wiki" claims the "screw jack was slipping"?

The wiki on ET-302 notes that, for a plane that had an Emergency AD, they thought a pilot with only 207 hours on type was thought a suitable choice.

 

[3DDave]

"These emergencies did not present as a classic runaway stabilizer problem, but initially as ambiguous unreliable airspeed and altitude situations"

In that case the pilots would set pitch and power. They did not. They also had a stick shaker, which they knew from the Emergency AD was a symptom that, combined with flap retraction, would cause nose-down trim requiring the cutout of the electric trim system.

 

[Alistair_Heaton]

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

i will post it for you again.

 

[3DDave]

"Engineers Sylvain Alarie and Gilles Primeau"

They alone claim this. "In reference to the Ethiopian Airlines flight, Alarie noted that without receiving a command from the MCAS or the pilots, the jackscrew slipped, and then slipped again as the aircraft accelerated and dove" (slipped being a translation of the original French.)

Then that should be clear from the FDR, from which you should be able to point to the time stamps. But there won't be any proof that anything slipped because there isn't a monitor of the turning of the jackscrew motor, unless you are claiming the jackscrew threads sheared off completely.

The wiki took it from this article:

https://ici.radio-canada.ca/nouvell...s-enquete-verin-systeme-anomalie-aeronautique

And what Gilles Primeau wants is the implementation of the usual precautions put on Fly-by-wire aircraft, on which software batteries are active. For example, sensors and monitoring software that would have detected abnormal movements of the cylinder and could potentially have blocked them.

So, there wasn't anything to actually detect this movement.

 

[3DDave]

A bit more detail from that article:

" At the start of the flight, they managed to counter the MCAS. MCAS goes off again, they manage to counter it again, but in the end, it's not enough. There is a very clear change in regime. The horizontal stabilizer suddenly begins to unscrew, unscrew and put the plane into a dive , observes Sylvain Alarie."

It "unscrews" at the end because MCAS is driving the screw and the pilots allowed. It's not being back-driven. Which is why this observation wasn't part of either final report.

 

[Alistair_Heaton]

ok fair enough on that one,

I wasn't going to go through 143 refs.

 

[3DDave]

No need to reaqd 143 refs - almost every statement in a Wikipedia page will have a reference; in this case the reference:

https://en.wikipedia.org/wiki/Maneuvering_Characteristics_Augmentation_System#Slippage_concern

only referred to [97]

One of the complaints made about Wikipedia is that people can just write whatever they want; the counter to that is that unreferenced claims are either questioned or deleted.

 

[Alistair_Heaton]

Well the rest of it looks pretty reasonable in relation to the lack of revision process. And risk analysis.

I am happy now that people that do know what they are talking about are now in charge of the certification. Plus required training.

And it's nothing like the original certification.

 

[Alistair_Heaton]

https://www.cnn.com/2024/03/23/business/united-airlines-faa-oversight/index.html

That's actually quiet a big deal for an airline and a very embarrassing restriction.

Members of Council 150,
We, your elected ALPA Representatives, feel it is our unfortunate responsibility to draw attention to several very concerning items. These issues have, thus far, been inadequately addressed. They pertain to the very core nature of our chosen profession. Simply put, our Safety Culture is under attack and enough is enough. We can not, in good conscience, continue to wait for our Flight Operations Management team to choose safety over anything else. While their words make for great PR, their actions have not matched those words and have directly led to the unfortunate circumstance in which we presently find ourselves. The “United Next” growth plan has seen a staggering 30% growth in just a few short years. However, that growth has come with strings attached. It has come hand in hand with an orchestrated erosion of our Safety Culture and our profession’s input into it. The FAA has similarly witnessed this and recently stepped in to take substantial action against United Airlines. We have lost the ability to approve new Line Check Pilots, issue type ratings, and have regulator-imposed restrictions on our ability to operate and grow our airline. We will also see an increased FAA presence in our daily operation. We are concerned of the damage already done, and this will be long lasting without an immediate and dramatic course reversal.
Who could’ve seen this coming?
Well, for starters, nearly every pilot. We are the ones who have “skin in the game” on every flight. We are the ones with a pulse on the operation. Our concerns have been continuously brushed aside in favor of activities such as Net Promoter Score modules in CQDL, Pilot Professional Development classes with an emphasis on Company feel-good slides, and APU policing. We’ve had these discussions on our flight decks nearly every trip, along with topics like “forced” Captain upgrades, and the continually decreasing flight experience levels of Captains, including instructors and Line Check Pilots.
Unfathomably, in the midst of our latest issues, a VP of a PR related department chastised one of our Captains via United’s “Bravo” recognition app for providing a safe and successful flight. Why? Because our Captain chose to use his time focusing on his crew, preflight duties and preparing for a safe flight, rather than coming out to the aisles to give his departure announcement. This is, in a nutshell, the root of the issues we face.
While Flight Ops Management has allegedly spoken to the individual to assure that doesn’t happen again, it is indicative of a much larger issue. This individual appeared to be less concerned about the safe operation of a flight, than whether the Captain was contributing to that flight’s NPS score, and likely this individual’s bonus.
When we were made aware of this occurrence, the indignation expressed amongst ourselves was loud and clear. Change is needed. It must come with safety as the primary, if not ONLY focus. Exampled by recent actions, Management seems inclined to continue down their path of removing pilot influence from Flight Operations. No longer do we have the SVP of Flight Ops position. Long serving Chief Pilots are leaving their offices and being replaced with Base Directors or whatever they call them now. Make no mistake, this is a prelude to further removing pilots from managing pilots. Human Resources and Labor Relations have never been as far reaching into pilot disciplinary events as they are today, sometimes bordering on harassment of our pilots.
Where does this leave us? Well, for starters, it leaves us as pilots under more scrutiny than ever before. We all need to reinvest in our Safety Culture and do so with vigor. Encourage each other on the flight decks to STOP when rushed, do your best to limit distractions. WHATEVER IT TAKES.
As professionals, we are great at what we do. None better. However, with new risks, comes a need for increased vigilance on each flight. 99.99% success is simply not good enough. Visitors on the flight deck before departure? Maybe ask the FAs to have them stop up afterwards if you’re not completely finished with your preflight duties. Self evaluate and ask if you’re truly ready to be an LCP or a new CA, or are you just chasing a paycheck? A few weeks at TK and OE will not make you ready if you aren’t already. Communicate with each other openly. Don’t skip probationary reports nor merely check the boxes with “great job”. Insist on good debriefings of appropriate items. These are key elements and tools to defend against risk and maintain a safe operation. Refocus on mentoring not just our new pilots, but each other. We are a half step away from the crisis that has been marching steadily towards us. Its now on our doorstep.
The members of your MEC are engaged with Flight Ops Management. We have provided suggestions for restoring our Safety Culture, though it ultimately remains to be seen if they are finally acted upon. The rapid execution of United Next and its promise of financial windfall has been blindly setting us up for this failure, despite our warnings to them which have previously been brushed aside. Hopefully, the FAA action will open some of their eyes and ears to the pitfalls within the changes they steadfastly pursue. Meanwhile, we all need to manage the new risk environment we operate in. The media, the FAA, and our passengers now have their attention focused upon us, the pilots of United Airlines. Every minor issue will be heavily scrutinized. Stay safe and stay out of the headlines.”

 

[LittleInch]

3DDAve,

You are persistent I'll give you that, but some things need comment here IMO.

"Already dealt with. All trim runaway stops when the jack screw hits the stops, therefore there cannot ever be runaway because the movement is not continuous, per this definition."

Come on, "Runaway" just means it keeps going without stopping, not that it continues to the end of the earth. Even a "runaway" train hits the end of the tracks at some point. The key factor is that at the stops, the stabiliser had grown over the different variations to be so much bigger that even full back movement of the elevator could not fight it and the plane simply kept on nose diving. To somehow say this wasn't trim runaway is not accurate IMHO..


"They also had a stick shaker, which they knew from the Emergency AD was a symptom that, combined with flap retraction, would cause nose-down trim requiring the cutout of the electric trim system."

The AD makes NO mention of flap retraction being a start point of MCAS activation. That only came out during the investigations as the details slowly emerged.

Quite why Boeing decided to make the STAB trim switches in series (essentially just duplicating the same function) compared to the previous dual switch where you could turn off the auto trim, but still keep the thumb switches alive I either can't remember or it was never explained. There went one of the Swiss cheese holes...



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[JohnRBaker]

I guess this was inevitable...

Boeing CEO to step down in broad management shake-up as 737 Max crisis weighs on aerospace giant

https://www.cnbc.com/2024/03/25/boeing-ceo-board-chair-commercial-head-out-737-max-crisis.html

An excerpt from the above item:

Boeing CEO Dave Calhoun will step down at the end of 2024 in part of a broad management shake-up for the embattled aerospace giant.

Larry Kellner, chairman of the board, is also resigning and will not stand for reelection at Boeing’s annual meeting in May. He will be succeeded as chair by Steve Mollenkopf, who has been a Boeing director since 2020 and is a former CEO of Qualcomm. Mollenkopf will lead the board in picking a new CEO, Boeing said.

And Stan Deal, president and CEO of Boeing Commercial Airplanes, is leaving the company effective immediately. Moving into his job is Stephanie Pope, who recently became Boeing’s chief operating officer after previously running Boeing Global Services.

The departures come as airlines and regulators have been increasing calls for major changes at the company after a host of quality and manufacturing flaws on Boeing planes. Scrutiny intensified after a Jan. 5 accident, when a door plug blew out of a nearly new Boeing 737 Max 9 minutes into an Alaska Airlines
flight.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[Alistair_Heaton]

So they have another accountant as a replacement....

 

[waross]

So they have another accountant as a replacement....

May we hope that this accountant will look at the ten years (or more) in the past, and the ten years (or more) in the future
rather than focusing on the next quarter share price and dividend.
I know.
I'm a dreamer.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[LittleInch]

Maybe the accountant will ask how come four bolts cost a few billion dollars...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[3DDave]

" "Runaway" just means it keeps going without stopping"

But it does stop. If it now means it keeps going but also stops then either it isn't runaway or there is a time limit. How great a time is defined for "runaway?"

"The AD makes NO mention of flap retraction being a start point of MCAS activation."

Sorry. That was part of the release of the Lion Air preliminary report, 120-150 mornings before they crashed. So it was information they knew, or should have known, or their Chief pilot knew or could have known, or their CAA knew, or could have known, were it not for the sins of greed and sloth.

I wondered in both incidents why a pilot, in a plane that is having what appears to be an aerodynamic problem of stalling that is stable and under control, would they decide to alter the aerodynamic configuration that is lower lift and unknown response.

"Quite why Boeing decided to make the STAB trim switches in series (essentially just duplicating the same function) compared to the previous dual switch where you could turn off the auto trim, but still keep the thumb switches alive I either can't remember or it was never explained. "

The explanation was that they did not want pilots to be diagnosing the failure rather than dealing with the symptoms. Since the trim switches 100% stopped the actions of MCAS during the use of the wheel trim that was not a problem.

What was a problem, aside from the ET-302 pilots never knowing what the word "neutral" meant, was they ignored the part that said "stay in the CUTOUT position for the remainder of the flight."

Recall the CUTOUT wasn't used on the Lion Air crash aircraft, so that meant nothing. On the ET-302 crash aircraft they re-enabled trim but only test that the electric trim worked before then trying to re-enable the autopilot which they were trained to disable when there was a stall warning, which was continuous on that flight.

 

[Alistair_Heaton]

They want to get rid flaps so they don't over speed them.

It can be quite a narrow window between stall and over speed with slats out.

The trim wheel motion on a 737 is pretty constant. It staying still for 3 seconds would be more noticeable than it moving for 5-10 seconds.

 

[3DDave]

"They want to get rid flaps so they don't over speed them."

This is accomplished by - setting pitch and power. Didn't ET-302 over-speed the plane anyway? Like nearly double the normal speed for that altitude?

What is noticeable is when the trim force on the wheel continues to go up and up and up and up and up and the pilots are like, "I have big biceps and no thumb."

 

[Alistair_Heaton]

Apart from the fact that it takes 15 seconds for the power to come off and if your nose is below 5 Deg nose up you will through flap limit in under 5 seconds.

I would be surprised if they didn't.

But can't remember the flow or what configuration they were in.

But the after departure clean up is pretty automatic. So to forget to break that flow is an unsurprisingly human factor mistake.

 

[1503-44]

BOEING CEO, COB AND COMMERCIAL VP LEAVING BY EOYr

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[3DDave]

Yes, yes. With a stick shaker rattling and a stall horn blaring, the ability to just shut those out and act as if nothing is going on is the sign of a well seasoned professional.

Oh, look, what the NTSB mentions about the flaps:

The NTSB acknowledges that information about the flap position required for
MCAS to activate did not appear in Boeing’s FCOM bulletin and the Federal Aviation
Administration’s airworthiness directive in response to the Lion Air flight 610
accident. However, Boeing provided that information in a multi-operator
message (MOM-MOM-18-0664-01B), which was sent to all “737NG/MAX Customers,
Regional Directors, Regional Managers and Boeing Field Service Bases” on
November 10, 2018 (after the Lion Air accident but before the Ethiopian Airlines
accident). Although the EAIB appended Boeing’s multi-operator message to the final
report, the EAIB failed to mention that the flaps information appeared in that
document; thus, this finding is misleading.

https://www.ntsb.gov/investigations/Documents/Response to EAIB final report.pdf

We propose that the probable cause in the final report present the following causal factors to fully reflect the
circumstances of this accident:
• uncommanded airplane-nose-down inputs from the MCAS due to erroneous AOA values and
• the flight crew’s inadequate use of manual electric trim and management of thrust to maintain airplane
control.
In addition, we propose that the following contributing factors be included:
• the operator’s failure to ensure that its flight crews were prepared to properly respond to uncommanded
stabilizer trim movement in the manner outlined in Boeing’s flight crew operating manual (FCOM)
bulletin and the FAA’s emergency airworthiness directive (AD) (both issued 4 months before the
accident) and
• the airplane’s impact with a foreign object, which damaged the AOA sensor and caused the erroneous
AOA values.

https://www.ntsb.gov/investigations/Documents/US comments ET302 Report March 2022.pdf

The EAIB really didn't want any other answers. Example:

Further, the draft report states that, because the EAIB did not participate in the testing in person,
it cannot comment on the observations. However, Collins invited the EAIB multiple times to
participate in the simulation testing and live demonstration of the testing, but the EAIB did not
accept these invitations.

2.3 The EAIB draft report incorrectly states (in several locations) that the MCAS made control of the airplane
“impossible” but neglects to state that, if the crew had manually reduced thrust and appropriately used
the manual electric trim, the airplane would have remained controllable despite uncommanded MCAS
input.