MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures Mk II

[fgrieu]

It is not clear (to me at least) how exactly the modified FC software (including tamed MCAS) can allow re-certification.

1) The original certification was heavily based on "grandfather rights" (an arrangement under which an aircraft can be approved per a variation of the original Type Certificate, simplifying certification and allowing to ignore some new requirements that the original did not have to meet). It is not sure to what degree the FAA will now allows that, much less all other certification authorities. Loss of all grandfather right would immensely complicate return to service, and the following.

2) MCAS is there to mitigate at least an unsatisfactory stick feel, which would be un-certifiable (without MCAS) under the current type certificate. Some speculate MCAS may even be required to mitigate a deeper nose-up tendency in some corners of the flight envelope. Thus MCAS should be highly reliable. But the current hardware is not meant for that: only two FC and AOA vanes, and some scenarios disable MCAS leaving the plane without its protection.

3) The elevator can't be actuated manually (using trim wheel) in some (abnormal) conditions of the flight envelope (heavy mistrim at high speed), because the muscular force of the pilots is just not high enough. This always has been a serious issue with the 737, worsened with design changes (smaller trim wheel) of the NG also applying to the MAX. There is evidence that this issue was involved in the ET302 crash. Partial mitigation (yoyo maneuver) is not longer taught to pilots, many simulators do not attempt to simulate trim wheel force, and it surfaced that those that do had not been properly simulating that.

4) It surfaced that in the opinion of a panel of FAA engineers, the MAX did not meet standards of protection against shrapnel that could be thrown by engine malfunction and could severe essential cables, leading to loss of control: the larger engines increase the risk, and the standards became more stringent. This judgment was apparently overruled, but the facts remains, and 1 seems to make it worse from a re-certification standpoint.

What's Boeing plan on these items ? I vaguely see a tenable position that with extra pilot qualification, the plane is flyable with MCAS disabled, and pilots have time enough to react so that the plane does not enter the abnormal conditions making the trim wheel inop. Can that can take care of 2/3, facing 1? And what about 4 facing 1?

[OldnGrounded]

Financial Times, today:

Boeing’s 737 Max suspension hits global supply chain (https://www.ft.com/content/86f58aea-20a7-11ea-92da-f0c92e957a96)

Sarah Provan and Archie Hall in London

Boeing’s decision to suspend production temporarily of its 737 Max airliner has hit the shares of UK and European suppliers to the US group, as concern deepens over when the aircraft will return to the skies.

Shares in France’s Safran, the world’s third-largest aerospace supplier, were one of the steepest fallers on the Stoxx 600 aerospace and defence index on Tuesday, declining about 3 per cent.

The Paris-based company warned in September that the grounding of the 737 Max would hit its cash flow by about €300m a quarter, up from the €200m that it estimated in the first quarter of the year.

Its forecasts were based on the Max being back in the air by the end of this year. The timetable for when regulators will allow the 737 Max, which was grounded after two fatal crashes, to return to service remains unclear.

Safran produces engines for Boeing through a joint venture with General Electric called CFM International.

In the UK, Senior, an engineering company that counts Boeing as one of its top customers, was the biggest decliner among suppliers, falling 9 per cent. The FTSE 250 group warned in August that margins at its aerospace business were going to be squeezed by the prolonged grounding of the Max.

The Hertfordshire-based company, which makes sensors and other high-tech components for equipment manufacturers in the aerospace, defence and power sectors, said on Tuesday that it will provide a further update on “the potential implications to its 2020 performance once it has clarification from its customers”. It added that its expectations for its performance in 2019 are unchanged.

Shares in a rival UK supplier Meggitt fell almost 2 per cent. The company said in November that margins would be “constrained” by the Max grounding, and would be towards the lower end of the 17.7 per cent to 18.2 per cent it had forecast.

Sheila Kahyaoglu, an analyst at Jefferies, said the decision would likely result in lay-offs across the supply chain. “The supply chain is unlikely to carry workers for 2-3 months in furloughs . . . that’s why this decision was so difficult and that’s why [Boeing] waited to December to do it.”

Boeing’s 737 Max supply chain also runs through a range of smaller suppliers in the UK. Relative minnows like Aeromet International, a Worcester-based supplier of advanced aluminium cast parts, and Maher, a Sheffield steel machinist, have also done work on the 737 Max.

Airlines have already been forced to delay their plans to return the Max to their fleets until March, a year after the second of two fatal crashes that killed 346 and forced the grounding of the fleet. Boeing’s plans to suspend production of the 737 Max (https://www.ft.com/content/0f4cbec6-2045-11ea-b8a1-584213ee7b2b) from next month comes as the company grapples with a lengthy regulatory review. The US group is to provide information regarding the production halt when it releases quarterly earnings next month.

Europe’s Airbus, Boeing’s major rival, was one of the index’s few risers, with a gain of 0.5 per cent.

[PEI_3721]

The reported of poor performance in checklist action during simulator tests might identify further problems.
Assuming that MCAS 2.0 is sufficiently protected from AoA input failure - MCAS trim is inhibited, then why should checklist items be of great concern.

Considering the MAX as an extension of the NG, the baseline alerts with AoA failure are the Air Data disagree alerts (speed, altitude), Feel Diff Pressure - higher stick force, together with AP disengagement and continuous Stick Shake. Also, there will be changes in the EFIS display of speed and altitude and the low speed awareness symbology, and AoA display if shown.
The addition of AoA (mis compare) alert might not be a significant burden; it is available for the NG.

We might confidently assume that there will be an MCAS ‘OFF’ (fail /inhibit) alert, but the consequences of this on flight restriction is not known.
Why should there be discussion about additional checks; would this involve further layer of trim inhibit - manual switching.
If so why; MCAS inhibit should be sufficiently robust so that pilots do not have to disable electric trim (assume no AP/FD due to Air Data Issues).

Why was there reference to a reset procedure; why should MCAS be reset. It might be expected that the aircraft can be flown safely - away from the edges of the flight envelope, and thus for landing similar to any other system malfunction. If not … what is the nature of the residual problem - stability, manual handling, stick force (higher forces due to Feel Diff).

If the problem has its roots in the combination of many alerts, then the after takeoff situation might be most limiting, irrespective of the accident crews performance. There is no need to inhibit MCAS (trim system) immediately if the flap inhibit works, but if it is inhibited, then it may be overly difficult to manage the flight and several drills without electric trim. The NG would be similar except for inhibiting the trim; which could strengthen any argument that pilot trimming is a high workload task in combination checklist actions.

Also see discussion on trim issues in https://www.pprune.org/rumours-news/627546-flydubai-crash-rvi-final-report-out-6.html#post10642086
Would the trim characteristics add problems with manual trim wheel operation and stick centering/feel, particularly when resolving stick shake and unreliable airspeed issues with higher stick forces ?
Would higher stick force (feel diff) change the feel - the ease of operating the trim wheel ?

[medod]

It is not clear (to me at least) how exactly the modified FC software (including tamed MCAS) can allow re-certification.

1) The original certification was heavily based on "grandfather rights" (an arrangement under which an aircraft can be approved per a variation of the original Type Certificate, simplifying certification and allowing to ignore some new requirements that the original did not have to meet). It is not sure to what degree the FAA will now allows that, much less all other certification authorities. Loss of all grandfather right would immensely complicate return to service, and the following.

2) MCAS is there to mitigate at least an unsatisfactory stick feel, which would be un-certifiable (without MCAS) under the current type certificate. Some speculate MCAS may even be required to mitigate a deeper nose-up tendency in some corners of the flight envelope. Thus MCAS should be highly reliable. But the current hardware is not meant for that: only two FC and AOA vanes, and some scenarios disable MCAS leaving the plane without its protection.

<snip>

This is my basic understanding too. However I think it might be the case that without MCAS, the MAX could not be certified today because of its pitch instability at high AoA. The MAX can’t be certified, anywhere, so long as it is dependent on AoA sensors for pitch stability in parts of the envelope, and only has two. To be certified, it has to have three. Yes I’m sure you could code laws to figure out which sensor is lying and which isn’t by comparison with the AHRS or whatever but no-one will certify that.

So the MAX will never fly again in commercial operation until it gets a third AoA sensor, the necessary flight control system to use three, and recertification. That’s a couple of years, at least. Heck, it might even be that it just can’t be certified. An Airbus in Direct Law is still certified...

[jimtx]

This is my basic understanding too. However I think it might be the case that without MCAS, the MAX could not be certified today because of its pitch instability at high AoA. The MAX can’t be certified, anywhere, so long as it is dependent on AoA sensors for pitch stability in parts of the envelope, and only has two. To be certified, it has to have three. Yes I’m sure you could code laws to figure out which sensor is lying and which isn’t by comparison with the AHRS or whatever but no-one will certify that.

So the MAX will never fly again in commercial operation until it gets a third AoA sensor, the necessary flight control system to use three, and recertification. That’s a couple of years, at least. Heck, it might even be that it just can’t be certified. An Airbus in Direct Law is still certified...

What pitch instability? It's just a nonlinear control response which might or might not affect the pilot. It apparently does not affect the autopilot although maybe MCAS is not needed for the autopilot because the autopilot is not capable of entering the flight regime which Boeing is keeping to itself.

[OldnGrounded]

What pitch instability?

That seems to be a question that has not yet been adequately answered -- at least not clearly and publicly. From the JATR report:

Recommendation R3.4: The FAA should review the natural (bare airframe) stalling characteristics of the B737 MAX to determine if unsafe characteristics exist. If unsafe characteristics exist, the design of the speed trim system (STS)/MCAS/elevator feel shift (EFS) should be reviewed for acceptability.

Observation O3.4-A: The original implementation of MCAS was driven primarily by its ability to provide the B737 MAX with FAA-compliant flight characteristics at high speed. An unaugmented design would have been at risk of not meeting 14 CFR part 25 maneuvering characteristics requirements due to aerodynamics.

Observation O3.4-B: Extension of MCAS to the low-speed and 1g environment during the flight program was due to unacceptable stall characteristics with STS only. The possibility of a pitch-up tendency during approach to stall was identified for the flaps-up configuration prior to the implementation of MCAS.

Finding F3.4-A: The acceptability of the natural stalling characteristics of the aircraft should form the basis for the design and certification of augmentation functions such as EFS and STS (including MCAS) that are used in support of meeting 14 CFR part 25, subpart B requirements.

Recommendation R3.5: The FAA should review 14 CFR 25.201 (Stall Demonstration) compliance for the B737 MAX and determine if the flight control augmentation functions provided by STS/MCAS/EFS constitute a stall identification system.

Finding F3.5-A: The nose-down pitch identified during Boeing flight tests for stall appears to the JATR team to be the product of system augmentation with flaps and gear up, and is likely due to stabilizer motion from the MCAS function.

Finding F3.5-B: The FAA-accepted Boeing flight test technique of freezing column deflection at the onset of EFS was perceived by the JATR team as possibly not meeting the requirements of § 25.201 for natural stall identification from nose-down pitch, not readily arrested. Column/elevator deflection data indicates that there may be an insufficient column input to attempt to arrest the nose-down pitch created by system augmentation.

Finding F3.5-C: The JATR team considers that the STS/MCAS and EFS functions could be considered as stall identification systems or stall protection systems, depending on the natural (unaugmented) stall characteristics of the aircraft. From its data review, the JATR team was unable to completely rule out the possibility that these augmentation systems function as a stall protection system

[Icarus2001]

So the MAX will never fly again in commercial operation until it gets a third AoA sensor, the necessary flight control system to use three, and recertification. That’s a couple of years, at least. Heck, it might even be that it just can’t be certified. An Airbus in Direct Law is still certified.
That is a very big call. I cannot say I agree with you Medod but who knows. The sharemarket is stil positive.

[AviatorDave]

That is a very big call. I cannot say I agree with you Medod but who knows. The sharemarket is stil positive.

You think it’s a big call? Boeing and the certifying authorities are well advised to not cock this up again by taking any shortcuts. If they do, and there is yet another accident which can be traced back to MCAS and/or basic problems with the aerodynamic stability of the airframe, Boeing is going to be toast, at least in the short/med haul sector.
Sure, the stock market may still hope that there is a quick short term solution for the MAX problem. But that very same stock market is not very loyal and will drop Boeing like a hot piece of charcoal on any new mishap.

[EDML]

What pitch instability? It's just a nonlinear control response which might or might not affect the pilot. It apparently does not affect the autopilot although maybe MCAS is not needed for the autopilot because the autopilot is not capable of entering the flight regime which Boeing is keeping to itself.

It doesn't matter for the AP because the AP doesn't care about stick force gradient.

[PEI_3721]

fgrieu, #1, medod, #4,
The basic aircraft was certificated on the basis of MCAS. The theory and inservice experience confirmed that this option is satisfactory, excepting for AoA malfunction.
Thus the approval to fly again depends on the robustness of the changes to protect the system from AoA malfunction; evaluated as required against existing requirements and recommendations from accident investigations.
Technically the second iteration of modification appears to be satisfactory. However, there appears to be issues with pilot interaction, using checklists, presumably after the system has failed safe, #3 considers these.

The aircraft is not inherently unstable; there is a reduction in stability margin in small areas of the flight envelope, which MCAS alleviates.
There should not be any significant concerns about abnormal flight without MCAS - after an inhibit - an assumption. The aircraft has ‘normal’ stability characteristic in most areas of the flight envelope - as demonstrated with lengthy time in service - but how often did MCAS work. Crews can be alerted to the need for care in the less stable ‘corner points’ when flying without MCAS.

The remaining oddity is trim. Historically the 737 trim has been ‘different’, which has changed (for the worse) with series development - extensive tech log discussion.
In the NG, a trim runaway appears to be acceptable, but depends on quick pilot reaction - trim inhibit, and as a last resort a yo-yo recovery manoeuvre (not in all situations - certification probability argument for acceptability).

The Max might have crossed the boundary of acceptability for timely pilot intervention and/or an increased need for, or impractical yo-yo.
How far does the trim run before MCAS shuts down, is this offset acceptable in every possible part of the flight envelope; with consideration of the variability and physical range of human ability to operate the trim wheel, (5sec ?)
How does a non MCAS Max differ from the NG; do aerodynamic differences effect the ability to trim with the wheel ?

The certification requirements involve judgement of how much piloting contribution can be assumed towards mitigating failures - with all alerted conditions coincident with, and consequential to an AoA failure. Whatever ‘piloting’ arguments have been used for NG have been negated by the two accidents in the Max; thus assessments are now clean sheet reappraisals by an authority under national and international pressure to demonstrate the highest quality processes.

[lomapaseo]

fgrieu, #1, medod, #4,
The basic aircraft was certificated on the basis of MCAS. The theory and inservice experience confirmed that this option is satisfactory, excepting for AoA malfunction.
Thus the approval to fly again depends on the robustness of the changes to protect the system from AoA malfunction; evaluated as required against existing requirements and recommendations from accident investigations.
Technically the second iteration of modification appears to be satisfactory. However, there appears to be issues with pilot interaction, using checklists, presumably after the system has failed safe, #3 considers these.

The aircraft is not inherently unstable; there is a reduction in stability margin in small areas of the flight envelope, which MCAS alleviates.
There should not be any significant concerns about abnormal flight without MCAS - after an inhibit - an assumption. The aircraft has ‘normal’ stability characteristic in most areas of the flight envelope - as demonstrated with lengthy time in service - but how often did MCAS work. Crews can be alerted to the need for care in the less stable ‘corner points’ when flying without MCAS.

The remaining oddity is trim. Historically the 737 trim has been ‘different’, which has changed (for the worse) with series development - extensive tech log discussion.
In the NG, a trim runaway appears to be acceptable, but depends on quick pilot reaction - trim inhibit, and as a last resort a yo-yo recovery manoeuvre (not in all situations - certification probability argument for acceptability).

The Max might have crossed the boundary of acceptability for timely pilot intervention and/or an increased need for, or impracticable, yo-yo.
How far does the trim run before MCAS shuts down, is this offset acceptable in every possible part of the flight envelope; with consideration of the variability and physical range of human ability to operate the trim wheel, (5sec ?)
How does a non MCAS Max differ from the NG; do aerodynamic differences effect the ability to trim with the wheel ?

The certification requirements involve judgement of how much piloting contribution can be assumed towards mitigating failures - with all alerted conditions coincident with, and consequential to an AoA failure. Whatever ‘piloting’ arguments have been used for NG have been negated by the two accidents in the Max; thus assessments are now clean sheet reappraisals by an authority under national and international pressure to demonstrate the highest quality processes.

Overall, excellent summary

But what to do about the bolded section above?

The masses of reader opinion are calling for a massive crackdown on the FAA-Boeing interaction process regarding product certification. But where is the update to the assumption about pilot responses to unreliable instruments and their aircraft response?

How can we expect a manufacturer to make a product that is airworthy yet confuses a crew? Is that in the certification review of the FARs or just a trust by the regulator that they can ultimately find blame outside their own processes?

Methinks this is not a Boeing problem to be buried in a grounding until the questions stop and enough pain endured

[Water pilot]

The aircraft is not inherently unstable; there is a reduction in stability margin in small areas of the flight envelope, which MCAS alleviates.
Could you expand on this statement? This sounds like the sort of thing that the shipyard's lawyer says after the boat tips over...

[Less Hair]

If it can't be fixed within a year can it ever be fixed?

[OldnGrounded]

fgrieu, #1, medod, #4,
The basic aircraft was certificated on the basis of MCAS. The theory and inservice experience confirmed that this option is satisfactory, excepting for AoA malfunction.

I don't think that's accurate. First, by definition, theory can't confirm anything. And it is doubtful that MAX with MCAS 1.0 saw enough inservice time to confirm that it was satisfactory except for AoA failure.

Technically the second iteration of modification appears to be satisfactory.

We have nothing but weakly-sourced reports about MCAS 2.0

The aircraft is not inherently unstable; there is a reduction in stability margin in small areas of the flight envelope, which MCAS alleviates.

Again, none of us have seen data on the aerodynamics of the bare airframe. And many, including JATR, think it would be wise to find out just how it behaves in those corners without MCAS.

There should not be any significant concerns about abnormal flight without MCAS - after an inhibit - an assumption.

Yes, so far, just an assumption.

The aircraft has ‘normal’ stability characteristic in most areas of the flight envelope - as demonstrated with lengthy time in service

The MAX has not had "lengthy time in service."

- but how often did MCAS work.

If anyone has any clue as to the answer to that question, it certainly hasn't been made public.

Crews can be alerted to the need for care in the less stable ‘corner points’ when flying without MCAS.

Assuming that the airplane can be certified to fly without MCAS.

How does a non MCAS Max differ from the NG; do aerodynamic differences effect the ability to trim with the wheel ?

Unless the regulations change, one way it differs is that it can't be certified.

[PEI_3721]

lomapasseo,
:ok:
Much of the judgement about human-system interaction is in the application of AMC 25.1302 ‘Installed Systems and Equipment for Use by the Flight Crew’ (I assume that you are familiar).
The application and processes for the 737 Max failed.

The requirement is ‘relatively’ new such that early versions of the 737 may not have had a full evaluation. The industry has struggled (continues to do so) with the human aspects. The dependence on judgement vs hard regulation requirers that both manufacturers and regulators understand and agree critical assumptions and justifications. This process was weakened with self certification and poor regulatory oversight, and thus the appropriate application of the requirement is central to the 737 Max re-evaluation.
The task involves both aircraft modification and reviewing / repairing the regulatory process, the latter requiring more regulators, trained and conversant with the 737, in regulation interpretation, and processes for evaluation, approval; … time.

The ‘massive crackdown on the FAA-Boeing interaction process regarding product certification‘ is required, but it’s not directly part of the current regulatory process; who oversees the regulators. Max flights don’t depend on this as it appears that the manufacturer is largely excluded from current ‘judgements’.

Water pilot, certification stability requirements depend on increasing stick force with speed reduction (fixed trim). This is particularly important at low speed where increasing pull helps identify approach to the stall. If the force required reverses - decreases, or the aircraft exhibits tendency to pitch-up into the stall, these identify unacceptable stability characteristics without being ‘unstable’. The details are within the lengthy and complex requirements of CS / FAR part 25.
The Max appears to differ in the nature of the low speed characteristics and also when manoeuvring at high speed - use of AoA / Mach vs speed; there are few precise details.

P.S. You or others might wish to see the free course https://www.futurelearn.com/courses/flight-mechanics stability is in week 4

[OldnGrounded]

From Bloomberg:

An Irish company that buys and leases airplanes sued Boeing Co. (https://www.bloomberg.com/quote/BA:US) in the U.S. to void contracts for almost two dozen 737 Max aircraft and to demand at least $185 million in damages, citing design flaws that led to two deadly crashes.

More (https://www.bloomberg.com/news/articles/2019-12-18/boeing-sued-by-irish-plane-lessor-to-void-deal-for-22-max-jets)

[PEI_3721]

OldnGrounded,
Certification approval is a mixture of theory, design, engineering, documentation, proof of concept, assessment, and testing. It does not depend on being inservice for some time.

There are some significant assumptions; reading between the lines, and extrapolation of what is known publicly …, … joining up the dots; but first what is a ‘dot’.

Normal stability throughout the flight envelope had to be demonstrated in certification. No abnormalities were identified (excluding the MCAS flight envelope). Indeed the Max ‘had to be the same’ as previous series.

The task is not to provide type certification without MCAS; the ‘naked’ 737 Max does not meet requirements. Within the certification process it is necessary to asses an aircraft for abnormal operation after a required system fails, e.g. 737 single engine flight is within certification, being ‘acceptable’ for emergency operation, safety recovery and landing.

The extent of 737 Max approval for abnormal operation with MCAS inhibited is not known; we assume that it would not involve significant flight restrictions - slow down, select flaps - trim. However, within that assumption, the extent and use of checklists appears to be a problem; human machine interaction.

The abnormal piloting task has to consider the overall operation with AoA disagree, other failed systems; simultaneously no MCAS - offset trim, recover attitude, continuous Stick Shake, Air Data disagree - use st by instruments, incorrect low speed awareness, increased stick force (feel diff), manual operated wheel trim.
The approval of this operation requires judgement, of piloting capability, in context, at any time, to public satisfaction via the FAA, with or without published reasoning.
First the FAA has to reacquire public trust, not change regulations.

[phylosocopter]

Is it possible for Boeing to somehow support its own stock price?

[golfyankeesierra]

And I as a hand flying pilot might not worry about a change in gradient. I use the column to put the attitude where I want it. But I can envision conditions where I might overcontrol in a dynamic state. I would want to see a clean windshear escape for one.

You are a cool dude not worrying about stick gradients, but when I handfly it is usually at minimum maneuvering speeds, that is high(er) AOA and I also make turns and look out the window as well so I do worry about stick gradients.
I also don’t follow your reasoning for windshear, that is instrument flying, overcontrolling is a known threat in any aircraft. It requires tunneling on pitch/ flightdirector guidance and stickforces are different from day to day operation already..

[Stribeck]

Certification approval is a mixture of theory, design, engineering, documentation, proof of concept, assessment, and testing self-imposed as a result of successful lobbying to the FAA.

Sorry, I couldn't resist! Seriously though, the trust aspect is a major factor now, especially outside the US.

FAA and Boeing has a bit of work to do in rebuilding this trust, and so far I don't know if there's been much progress. Considering how a "released cargo door" can turn out to be a split fuselage (777x wing loading), I'm not sure how to interpret light stick load in relation to pitch up tendencies of the Max. I would prefer to see results of the bare airframe stall characteristics (as asked for by JATR in recommendation R3.4) before taking Boeings word for what is the purpose of MCAS.

[turbidus]

For the -800 AP engage was min 400', but most SOP was higher. Is this the same for the MAX?

[OldnGrounded]

OldnGrounded,
Certification approval is a mixture of theory, design, engineering, documentation, proof of concept, assessment, and testing. It does not depend on being inservice for some time.

Of course. I was responding to an assertion that theory and long service had "confirmed" satisfactory operation excep in the case of AoA failure. That, rather obviously, is not accurate.

Normal stability throughout the flight envelope had to be demonstrated in certification. No abnormalities were identified (excluding the MCAS flight envelope). Indeed the Max ‘had to be the same’ as previous series.

Yes, and concern about possible, not-previously-identified issues are rather widespread, which is what I said.

Anyway, I think you may be responding to an interpretation of what I wrote rather than to the plain language. I'll take a close look and stand corrected if I "spoke" in error.

[OldnGrounded]

Is it possible for Boeing to somehow support its own stock price?

Sure, Boeing is a master at that. Dividends and buybacks have been key parts of the effort for quite some time, and the list of other possible tactics is long.

[krismiler]

Many old aircraft wouldn't meet today's certification requirements and that's is what the B737 basically is, an old generation jet tarted up. Imagine trying to get the B707 certified against modern regulations concerning handling, performance and safety. It would be a nightmare, easier to make a clean start with a new aircraft designed with today's regs in mind, incorporating modern systems in the design process, rather than trying to bolt them on afterwards.

Boeing have some of the best brains in the industry working for them, state of the art production facilities and are capable of making a class leading narrowbody replacement for the B737. Everything was going well until the B787 came along at which point it was apparent that the things were going off the rails. The "old" Boeing Company produced some excellent aircraft such as the current generation B777 which dominates its section of the market and has an enviable safety record.

Hard decisions need to be made in the next few weeks:

1. Bite the bullet and pull the plug on the MAX, scrap 400+ airframes, nearly 100 fuselages and pay everyone compensation. Back to the drawing board for a new type designed by engineers, not accountants and properly certified by the FAA. Whilst this would be the best solution, the amount of money involved would be colossal given the 5 - 10 year lead time, expense of developing a new type and greatly reduced income during this time. Government support along the lines of that given to the auto industry would be necessary on the "too big to fail basis". Also all the rhetoric about EU support for Airbus would seem rather hypocritical.

2. Persevere with getting the MAX flying again at whatever cost whilst hoping the band aid solution is acceptable to aviation authorities in the rest of the world, particularly the Chinese. Develop a replacement as quickly as possible alongside changing the company culture back to quality and safety instead of cost cutting and share price.

If the MAX solution isn't unanimously accepted by the world's aviation authorities, which is quite possible, and the type is only approved to fly in certain regions, then Boeing will be practically giving them away in order to maintain market share and customers. Complaints about dumping would undoubtedly be forthcoming to the WTO, sound familiar ? Airlines will be offering seats for free to those willing to fly on an aircraft which is banned on safety grounds in other countries.

After years of accusations of state support for Airbus, it will be interesting to hear the American explanation if they are forced to step in and prop up Boeing, which is becoming a real possibility given the contribution it makes to the US economy and knock on effects of a failure.

At one time Britain dominated the aircraft industry and was a major car producer, that all changed. Unless Boeing get their act together quickly, we could be watching a "sea change" in the world aerospace industry with Airbus dominating, the Chinese taking second place and Boeing coming third.

[Takwis]

2. Persevere with getting the MAX flying again at whatever cost whilst hoping the band aid solution is acceptable to aviation authorities in the rest of the world, particularly the Chinese. Develop a replacement as quickly as possible alongside changing the company culture back to quality and safety instead of cost cutting and share price.


These two solutions appear to me to be mutually exclusive.

[krismiler]

Any fix to the MAX in its present form would be a band aid solution to a fundamentally flawed design, this may or may not be acceptable depending on the quality and strength of the bandage. If not, see solution #1.

Whatever happens, cost cutting and share price need to take a backseat to the ethos of safety and quality.

[Loose rivets]

Develop a replacement as quickly as possible alongside changing the company culture back to quality and safety instead of cost cutting and share price.

As I'm sure I've mentioned, I don't think customers world-wide would be very happy about the value of their MAX acquisitions.

A middle road? Possibly an agreed loss making price based on ten years use of the aircraft. Airlines win and there's some revenue to buffer the losses. However, my heart sank when I saw the lawsuit filed by the Dublin firm. Could it be that's why Dennis ordered the suspension of production?

[tdracer]

If Boeing were to give up on the MAX - not getting the grounding lifted, buying back and scrapping the previously delivered MAX aircraft plus over 400 more built but undelivered MAX - the resultant total loss would be well in excess of $100 billion (USD). Even if Boeing survived such a hit (not to mention the impacted suppliers), coming with a clean sheet replacement and putting it into production would take a decade. Just financing such a new aircraft program is going to be a challenge after taking a $100+ billion hit. Boeing might even decide to concede the narrow body market and focus on wide bodies.
I doubt even the biggest Airbus fans would see granting them a virtual monopoly on the narrow body market for at least the next decade as desirable for the long term health of commercial aviation.

[Icarus2001]

Any fix to the MAX in its present form would be a band aid solution to a fundamentally flawed design I think that this is a massive overstatement of the situation. Fundamentally flawed? Really?

The reality is the aircraft flew for nearly two years before the first incident. Both crashes related to the AoA vane and crew responses to an "unknown" system, at least the first crash.

The defect is reliance on a single input to a system with a great deal of authority to put the aircraft out of trim. This is significant in an industry where many pilots are apprehensive about hand flying and may have lost the trim response reaction that may have once had, or never did.

The MCAS is fixable. What remains in question is whether regulatory agencies will approve the fix and whether politics will play a large part in the answer to that.

[Water pilot]

At one time Britain dominated the aircraft industry and was a major car producer, that all changed. Unless Boeing get their act together quickly, we could be watching a "sea change" in the world aerospace industry with Airbus dominating, the Chinese taking second place and Boeing coming third.
With the investments that they are doing into aerospace, China is not going to be second place unless we in the west get our act together pronto...

[krismiler]

This is significant in an industry where many pilots are apprehensive about hand flying and may have lost the trim response reaction that may have once had, or never did.

The skills available and the skills required must match, a state of the art supersonic fighter requires a thoroughly trained and highly skilled pilot which the operating airforce supplies through careful selection and lengthy instruction. Boeing must have known about the deterioration in flying skills and training levels and should have accounted for this by making the aircraft easier to fly, and building in safety systems like Airbus did with its ECAM and flight envelope protections. Basically, Airbus dumbed down it's entry level product to suit the new generation of pilots who would be flying it whereas Boeing didn't.

The MAX is fundamentally flawed because it took the basic B737 design way past the point where it was supposed to go. It was never meant to have a fuselage of that length or engines of that size. It should have been put to bed with the last 200 series in the 1980s and a clean sheet design produced. Even the 300 series wasn't meant for high bypass engines and had to have the bottom of the cowlings flattened out, the 700 series was an improvement but by that stage the systems should have been brought up to modern standards rather than trying to ride along on the original type certificate. The MAX shouldn't have been produced if it lacked modern safety systems and required MCAS to alleviate an aerodynamic problem.

[derjodel]

Is it possible for Boeing to somehow support its own stock price?

yes, through buyback

https://www.google.com/amp/s/amp.ft.com/content/4549b164-f589-11e9-a79c-bc9acae3b654

[esa-aardvark]

The reality is the aircraft flew for nearly two years

How long did the Space Shuttle fly before the first disaster ?

[jimjim1]

Is it possible for Boeing to somehow support its own stock price?

Yes. They have a Public Relations smoke and mirrors department.

[Sallyann1234]

The reality is the aircraft flew for nearly two years

How long did the Space Shuttle fly before the first disaster ?

Has any other passenger transport aircraft achieved a death rate of 137 per annum ?

[rog747]

MCAS seems so deeply rooted in the 737 MAX's flight control systems it seems pretty obvious to most of us here that Boeing still cannot fathom out, nor procure a safe fixable software rewrite/redesign/patch solution, (whatever you want to name it) to gain back the aircraft's stability thus to get it back in line with it's 1967 737-100/200 type approval Grandfather rights certificate,

Thus the current 737 MAX air frame is unstable (as is) in certain flight envelopes, thus un-certifiable on that old type ticket approval.(and likely should never have been approved)
Which is we we are at right now with all new production halted after months of soothing noises, and lots of hand wringing, but NO fix.

To now start a re-design of the air frame, or part of it (Thus to remove the need for MCAS) will surely mean a new type approval needed and 737NG crews will not be able to fly such a
reincarnation on the same licence. (which was not part of the MAX deal to airlines as we know)

[Callsign Kilo]

To now start a re-design of the air frame, or part of it (Thus to remove the need for MCAS) will surely mean a new type approval needed and 737NG crews will not be able to fly such a
reincarnation on the same licence. (which was not part of the MAX deal to airlines as we know)

Doesn’t matter, that ship has sailed; a long time ago. Boeing no longer has the luxury to bow to commercial forces that originally demanded a ‘same type’ certificate. This has been a long story that can be traced as far back to the development of the NG and the demands Southwest Airlines, for one, maybe even further and possibly with others? Was the 800/900 NG not considered longitudinally unstable hence the requirement for the huge tail surface/rudder? Someone already mentioned that the fuselage of the 737 was never intended to be the length that it eventually became.

[Loose rivets]

Has any other passenger transport aircraft achieved a death rate of 137 per annum ?

This is utterly meaningless. Statistics based on two incidents . . . well, just isn't.

The following is based on years of strong feelings about ETOPS and indeed, very inexperienced P2's.

I coined the phrase years ago, randomness comes in lumps. Also, given the two AoA sensor failures were of a disparate nature, having two failures so close together was bizarre bad luck. Yes, I know the fact that one item failing and causing such chaos is the prime issue, but that core failure in each case was because of a third-party manufacturer's design (or refurb company's quality control) in the first accident, and perhaps an 'Act of God' in the second. However, I'm not so sure about that. The unit is mechanically complex and at first glance, robust. But as we've seen, it has frailties; certain vulnerabilities that make the continued use of it very questionable. Use the output of two? Still open to a statistical lump, but so is flying over water with one engine out.

And that would bring me to having one experienced pilot and a kid out of school as the total means of controlling all this wondrous technology. What is incredible is the historic wellbeing of the only really competent soul on board - specifically where the P2 is very inexperienced. I suppose having the captain out of the loop leaves a situation much like the worst ETOPS scenario. The numbers favour success but really don't make much allowance for the lumpiness of statistics.

[Sallyann1234]

This is utterly meaningless. Statistics based on two incidents . . . well, just isn't.

The following is based on years of strong feelings about ETOPS and indeed, very inexperienced P2's.

I coined the phrase years ago, randomness comes in lumps. Also, given the two AoA sensor failures were of a disparate nature, having two failures so close together was bizarre bad luck. Yes, I know the fact that one item failing and causing such chaos is the prime issue, but that core failure in each case was because of a third-party manufacturer's design (or refurb company's quality control) in the first accident, and perhaps an 'Act of God' in the second. However, I'm not so sure about that. The unit is mechanically complex and at first glance, robust. But as we've seen, it has frailties; certain vulnerabilities that make the continued use of it very questionable. Use the output of two? Still open to a statistical lump, but so is flying over water with one engine out.

And that would bring me to having one experienced pilot and a kid out of school as the total means of controlling all this wondrous technology. What is incredible is the historic wellbeing of the only really competent soul on board - specifically where the P2 is very inexperienced. I suppose having the captain out of the loop leaves a situation much like the worst ETOPS scenario. The numbers favour success but really don't make much allowance for the lumpiness of statistics.
Yes of course it was meaningless. It was a response to the equally meaningless point that the MAX hadn't crashed for nearly two years.

[OldnGrounded]

The MCAS is fixable. What remains in question is whether regulatory agencies will approve the fix . . .

If we're talking about whether the MAX returns to service with MCAS or not, it's only fixable if regulators approve the fix. Absent approval, a "fix" is just a proposal.

. . . and whether politics will play a large part in the answer to that.

Politics is the way people govern themselves and each other. It plays a large part in every collective process and decision.

[MurphyWasRight]

.....
However, my heart sank when I saw the lawsuit filed by the Dublin firm. Could it be that's why Dennis ordered the suspension of production?

I doubt that was the trigger, BA have telegraphed for a while that they would have to suspend production if the grounding extended past the end of 2019.
I suspect it is due to "simple" (that is if you have an advanced accounting degree which I don't ) math balancing the cost of continued production against the cost of a shutdown/restart.
At some point the cost of cash to cover production/storage would start to go up significantly.

Other factor could be advanced payments that were due X months before scheduled delivery, I would guess (understatement here) that those have pretty much dried up.

[Dave Therhino]

The reality is the aircraft flew for nearly two years

How long did the Space Shuttle fly before the first disaster ?

The 737 Max fleet flew for a bit under 400,000 flight hours before the first accident, and the second occurred with the fleet at just under 800,000 hours. The demonstrated catastrophic accident rate at that point was about 1/400,000 per flight hour, or about 3x10E-6. This is roughly 100 times worse than the overall average transport airplane rate of catastrophic accidents due to all causes in the developed nations of Europe, North America, and Asia. This is about what you'd expect with non-fail-safe system design in just one truly critical system with dependence on typical electro-mechanical devices.

The rate of AOA sensor failure on the max was not unusual. If you monitor AOA sensor failures across a broader fleet, their average failure rate is consistent with the max experience. They occur for various reasons, and bird strikes are not the most common reason, but the average rate of failure is comparable. I've seen several reports on the NG over the past year for example.

The space shuttle's operating environment was very different and its mission was inherently high risk. Its average rate of a catastrophic event during launch and re-entry was about 1/100 per flight hour even with excellent systems designs due to the need for minimum weight and the operating conditions of orbital speeds and transition from and to flight in the atmosphere. Its relevance to the max issues is limited other than to show what first-class critical flight control systems design looks like.

[esa-aardvark]

Dave Therhino (https://www.pprune.org/members/404945-dave-therhino)

Shuttle - I think you mean per flight. Back when I worked the figure was 1/100 per flight.
I think the real concern is that Boeing programmed their flight software - MCAS
to rely on a potentially unreliable sensor. MCAS was not able (programmed) to detect
the failing sensor. Perhaps MCAS should have had a sanity check on reported AOA.
How one validates such an apparently Ad-hoc piece of software is beyond me.

My previous comment should have indicated that the expectation of an event is in the numbers
that you (NASA or Boeing or FAA) should be calculating with.

[Less Hair]

How about leaving MCAS the way it was and just change the AoA-sensors to some failsafe (including wrong installation and birdstrike) system? Like LIDAR or similar?

[jbcarioca]

Has any other passenger transport aircraft achieved a death rate of 137 per annum ?
Maybe not since 1952 and we all know what happened to:
de Havilland DH 106 Comet

[Dave Therhino]

Dave Therhino (https://www.pprune.org/members/404945-dave-therhino)

Shuttle - I think you mean per flight. Back when I worked the figure was 1/100 per flight.
I think the real concern is that Boeing programmed their flight software - MCAS
to rely on a potentially unreliable sensor. MCAS was not able (programmed) to detect
the failing sensor. Perhaps MCAS should have had a sanity check on reported AOA.

My previous comment should have indicated that the expectation of an event is in the numbers
that you (NASA or Boeing or FAA) should be calculating with.

I agree the number is also a good approximation of the per cycle risk because launch and re-entry were by far the most risky phases of flight. There were something like 150 missions (it's been a while since I added them up for a study), and two accidents, one on launch and one on re-entry. I specifically gave a ballpark per hour rate for launch and re-entry, for which I guessed 1 hour of exposure per cycle to those phases of flight. The risk in orbit is much lower, but still quite high theoretically compared to a commercial flight, though the record was good for those 150 or so flights.

I'm not sure I'm grasping everything you were trying to say with the rest of your comment, but my point was the AOA sensor behavior in the max fleet was not a huge outlier failure-rate wise, and it was the system architecture that caused the problem. I think we are probably saying the same thing.

[Water pilot]

The sensors can always fail, even multiple sensors will fail in the same way sometimes (icing.) You have to make sure that when they fail, the plane degrades gracefully and predictably rather than pointing its nose at the ground. I seem to remember that some European guys were working on such a concept, whatever happened to it?

It occurs to me that all of the solutions that Boeing is now proposing (to a problem that they still have trouble admitting exists) were solutions that had to have been considered and discarded during the initial design of the MAX. They have proposed nothing that would have incurred any significant cost to the program, so why is this new way better? We are now trading out false activation of MCAS for false deactivation, and if MCAS was so important that it was worth the 346 lives lost why are we so casually disabling it? Remember that Boeing told the American President that the plane was perfectly safe after the second accident.

[Sallyann1234]

Maybe not since 1952 and we all know what happened to:
de Havilland DH 106 Comet

Actually no.
The Comet 1 was in airline service for just under two years before grounding, the same as the MAX.

In that time it killed 110 souls, compared with the MAX's 346.

Much smaller aircraft, of course.

[slacktide]

yes, through buyback

https://www.google.com/amp/s/amp.ft.com/content/4549b164-f589-11e9-a79c-bc9acae3b654

The article you linked to states that Boeing expects to not pursue stock buybacks for the next several years.

In fact, Boeing previously announced that they had stopped buybacks in mid-March, during the Q1 2019 earnings call on 24 April 2019. Transcript: https://s2.q4cdn.com/661678649/files/doc_financials/quarterly/2019/q1/1Q19-Earnings-Call-Transcript-(1).pdf (https://s2.q4cdn.com/661678649/files/doc_financials/quarterly/2019/q1/1Q19-Earnings-Call-Transcript-(1).pdf)

Reviewing the 1Q, 2Q, and 3Q quarterly reports confirms this. $2341M worth of common shares were repurchased in Q1, $310M repurchased Q2 (with a note in the quarterly report that these were contractually obligated) and $zero repurchased Q3. Want to wager on what Q4 will say?

https://investors.boeing.com/investors/financial-reports/default.aspx

[turbidus]

Wonder if they kept the -800 and -900 jigs? Just start building those again.

[slacktide]

I have now realised that I may have been wrong about the decline in Boeing dating back to the cancellation of the B757 program. It may have started three years earlier.

Quote
On September 4, 2001, the Boeing Company moves its world headquarters from Seattle to Chicago. The decision to leave Seattle, announced on March 21, 2001, affects about 1,000 jobs.

Could this be relevant to the current problems ?

The 757 was cancelled because it received zero orders in 2002, 7 orders in 2003, zero orders in 2004, and zero orders in 2005. It's not a conspiracy, it costs a fortune to maintain capital equipment and real estate to support a product that is not generating revenue.

Many would point to the merger with McDonnell-Douglas in 1997 as the point where Boeing's culture and direction shifted. The relocation of the headquarters to Chicago directly traceable to that event. Boeing's troubles could be traced to McDonnell Douglas purchase - LA Biz Observed (http://www.laobserved.com/biz/2013/01/boeings_troubles_cou.php)

[MPN11]

Of course, the failure of today's Boeing 'Starliner' launch just increases confidence.

I heard there was something wrong in the programming of rocket burn ....

[MechEngr]

I agree the number is also a good approximation of the per cycle risk because launch and re-entry were by far the most risky phases of flight. There were something like 150 missions (it's been a while since I added them up for a study), and two accidents, one on launch and one on re-entry. I specifically gave a ballpark per hour rate for launch and re-entry, for which I guessed 1 hour of exposure per cycle to those phases of flight. The risk in orbit is much lower, but still quite high theoretically compared to a commercial flight, though the record was good for those 150 or so flights.

I'm not sure I'm grasping everything you were trying to say with the rest of your comment, but my point was the AOA sensor behavior in the max fleet was not a huge outlier failure-rate wise, and it was the system architecture that caused the problem. I think we are probably saying the same thing.

Both accidents were on launch. The final destruction of the second shuttle was delayed until re-entry, but Shuttle Columbia was fatally damaged during its launch for very similar reasons to the fatal damage of Shuttle Challenger; an acceptance of repeated damage due to previously noted defects in the design and a willingness to continue with them unresolved.

I think the launch event, from engine ignition to orbit is about 8-1/2 minutes, with the boosters running slightly more than 2 minutes. https://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts121/launch/qa-leinbach.html

[MechEngr]

Wonder if they kept the -800 and -900 jigs? Just start building those again.

They aren't fuel efficient enough.

[Fly Aiprt]

Of course, the failure of today's Boeing 'Starliner' launch just increases confidence.

I heard there was something wrong in the programming of rocket burn ....

Rocket ignition timing relying on a single clock. Which failed...

[MurphyWasRight]

Rocket ignition timing relying on a single clock. Which failed...
Not enough info released yet to say for sure, could also have been a mistake in a timing driven script that had an incorrect value, in hotel layover terms : clock correct, wrong alarm time set.
Either way not a good day for Boeing.

I almost missed a flight once due to the classic AM/PM mistake, always use 2 alarms for anything critical since then.

Now back to our regularly scheduled "not rocket science" 737/MAX programming.

[Grebe]

Rocket ignition timing relying on a single clock. Which failed...

The cause of the issue, according to NASA, was with a timing system.

Bridenstine said the mission elapsed timing system had an annonmally, so the vehicle thought it was a different time when it was supposed to fire the engines.

NASA officials said they were eventually able to get the engines burning and the spacecraft is in orbit and doing well.



The $ 20 Timex took a multi G licking- but didn't keep ticking.

But look at the $$ saved and schedule met

[sooty655]

The cause of the issue, according to NASA, was with a timing system.

Bridenstine said the mission elapsed timing system had an anomaly, so the vehicle thought it was a different time when it was supposed to fire the engines.

NASA officials said they were eventually able to get the engines burning and the spacecraft is in orbit and doing well.
Doing so well that it won't rendezvous with the ISS and will be returning early. Sounds like NASA officials are taking over the role of the Boeing smoke and mirrors department.

[Lake1952]

Has any other passenger transport aircraft achieved a death rate of 137 per annum ?

Actually yes... if you go back and research DC6 or Lockheed Constellation or even DC3s, there were many accidents each year that added up to that number of fatalities and much more! Many of the accidents were no due to the aircraft itself. Even the B707 and DC8 had more annual fatalities.

[maxter]

This is utterly meaningless. Statistics based on two incidents . . . well, just isn't.

The following is based on years of strong feelings about ETOPS and indeed, very inexperienced P2's.

I coined the phrase years ago, randomness comes in lumps. Also, given the two AoA sensor failures were of a disparate nature, having two failures so close together was bizarre bad luck. ………….
.
Certainly bad luck for those who died due to poor design at best or an apparent careless concern for real safety over profit more than likely

[Bend alot]

How about leaving MCAS the way it was and just change the AoA-sensors to some failsafe (including wrong installation and birdstrike) system? Like LIDAR or similar?
Repeated activation is an issue.
What is required when MCAS has failed safe, and how will the crew know?
The original version used one sensor - this was because of an incorrect classification made during design.
Such a change would possibly require extra training as a minimum but also exclude the grandfather rights.
It is not a software fix.

As for the return to service of the MAX - I think the March date will not be correct.
I can not see the FAA making such a important decision without the second report being released, that is due in March and while the FAA will get an early preview. I think they will want the public reaction if such things like manual trim wheel get a detailed mention.

[OldnGrounded]

Press release from yesterday:

FlyersRights Sues FAA For Refusal To Release Boeing 737 MAX Records

Supported by a Team of Aviation Professionals Arguing for Transparency and Independent Analysis Before Any Decision to Unground the MAX is Made

News provided by

FlyersRights.org (https://www.prnewswire.com/news/flyersrights.org) Dec 19, 2019, 17:04 ET




WASHINGTON, Dec. 19, 2019 /PRNewswire/ -- FlyersRights.org, the largest airline passenger organization, has filed a lawsuit in U.S. District Court in Washington, D.C. (1:19-cv-03749-CKK) seeking release of the Boeing Corporation's proposed changes to the 737 MAX submitted to the Federal Aviation Administration (FAA).

FlyersRights.org previously submitted a Freedom of Information Act (FOIA) request for the records on November 1st seeking expedited treatment, but the FAA failed to respond.

Supporting the lawsuit are seven aviation experts who declared that they need the FAA to release technical details to them and other independent experts in order to be able to evaluate whether the 737 MAX is safe to fly.

Paul Hudson, President of FlyersRights.org and member of the FAA's Aviation Rulemaking Advisory Committee since 1993, explained, "Trust in the FAA and Boeing has been shattered due to astounding revelations of misfeasance and incompetence in originally certifying the 737 MAX aircraft as safe. Accordingly, to regain public confidence, the flying public needs and deserves independent expert evaluations of the changes that Boeing and FAA may deem sufficient to unground the aircraft."

The seven aviation experts who have submitted declarations in favor of transparency and independent evaluation are:

Chesley "Sully" Sullenberger- Retired airline captain, famous for the "Miracle on the Hudson" landing and aviation safety expert for over four decades

Association of Flight Attendants-CWA- The largest flight attendants union, with nearly 50,000 members at 20 airlines

Michael Neely- Thirty-three years of experience in commercial and military aircraft development programs since 1983, working for Boeing from 1995-2016 serving in Multi-Discipline Engineering and Program Office roles

Javier de Luis- PhD Aeronautical engineer and scientist for 30 years and former lecturer at MIT

Michael Goldfarb- Aviation safety management consultant and former Chief of Staff and Senior Policy Adviser to the FAA Administrator

Gregory Travis- Computer software engineer with over 40 years of experience and pilot with over 30 years of experience

Paul Hudson- President of FlyersRights.org and long-time airline passenger safety advocate

The FOIA request can be found here: (https://c212.net/c/link/?t=0&l=en&o=2677312-1&h=3864858747&u=https%3A%2F%2Fflyersrights.org%2Fwp-content%2Fuploads%2F2019%2F12%2FFlyersRights-10.31.19-FAA-FOIA-Expedited-Request.pdf&a=%C2%A0)
https://flyersrights.org/wp-content/uploads/2019/12/FlyersRights-10.31.19-FAA-FOIA-Expedited-Request.pdf (https://c212.net/c/link/?t=0&l=en&o=2677312-1&h=2825592199&u=https%3A%2F%2Fflyersrights.org%2Fwp-content%2Fuploads%2F2019%2F12%2FFlyersRights-10.31.19-FAA-FOIA-Expedited-Request.pdf&a=https%3A%2F%2Fflyersrights.org%2Fwp-content%2Fuploads%2F2019%2F12%2FFlyersRights-10.31.19-FAA-FOIA-Expedited-Request.pdf)

The complaint can be found here: (https://c212.net/c/link/?t=0&l=en&o=2677312-1&h=2066438859&u=https%3A%2F%2Fflyersrights.org%2Fwp-content%2Fuploads%2F2019%2F12%2FFlyersRights-v-FAA-Boeing-MAX-FOIA-Complaint.pdf&a=%C2%A0)
https://flyersrights.org/wp-content/uploads/2019/12/FlyersRights-v-FAA-Boeing-MAX-FOIA-Complaint.pdf (https://c212.net/c/link/?t=0&l=en&o=2677312-1&h=2784841011&u=https%3A%2F%2Fflyersrights.org%2Fwp-content%2Fuploads%2F2019%2F12%2FFlyersRights-v-FAA-Boeing-MAX-FOIA-Complaint.pdf&a=https%3A%2F%2Fflyersrights.org%2Fwp-content%2Fuploads%2F2019%2F12%2FFlyersRights-v-FAA-Boeing-MAX-FOIA-Complaint.pdf)

FlyersRights.org is represented in court by Joseph E. Sandler of Sandler, Reiff, Lamb, Rosenstein & Birkenstock P.C., Washington, D.C. FlyersRights.org (https://c212.net/c/link/?t=0&l=en&o=2677312-1&h=302611613&u=http%3A%2F%2Fflyersrights.org%2F&a=FlyersRights.org), established in 2007, is the largest airline passenger organization. It publishes a bi-weekly newsletter, operates a free hotline for airline passengers 877- FLYERS6, advocates for passenger rights and interests, represents passengers on the FAA Aviation Rulemaking Advisory Committee dealing with air safety, and maintains a staffed office in Washington, D.C.

See: FlyersRights.org or https://twitter.com/FlyersRights (https://c212.net/c/link/?t=0&l=en&o=2677312-1&h=3846817089&u=https%3A%2F%2Ftwitter.com%2FFlyersRights&a=https%3A%2F%2Ftwitter.com%2FFlyersRights). Media line 800- 662-1859. FlyersRights.org, 4411 Bee Ridge Road, 274, Sarasota, FL 34233

SOURCE FlyersRights.org

[Bend alot]

Press release from yesterday:
This just got another layer of messy!

[OldnGrounded]

This just got another layer of messy!

Yeah, no kidding.

I just did a quick read of the complaint. The argument is strong and the FAA clearly screwed up by not responding to the FOIA request with the prescribed time limits, which should make the case ripe for judicial review. Plaintiff's lawyers, Sandler Reiff, are fairly heavy-hitting DC political and regulatory practitioners.

We need our real aviation lawyer, Willow Run, to weigh in on this, but a good guess would be that, although courts give deference to regulators on matters like this, this one probably won't go away quickly or easily, even if the district court isn't eager to deal with it.

[MechEngr]

Repeated activation is an issue.
What is required when MCAS has failed safe, and how will the crew know?

This is several questions. The first is whether the software that runs the MCAS algorithm is working correctly and how would the crew know it wasn't. This is the same unsolvable problem that software has always had. The usual approach is to hand an algorithm to a bunch of different software developers to run on different architecture computers and then depend on some other algorithm to decide if the answers are all close enough to select the "truth." This is seen in 2-of-3 voting systems, which are more, but not always, reliable.

The second is how will the crew know that MCAS software is operating correctly, but based on false inputs. This is similar to the first case because the crew isn't ever given raw data; it's all processed through some algorithm so it's back to some voting scheme. The way around algorithms would be to make a selsyn system that moved a mechanical AoA needle on the instrument panel, but it would not help if the needle or the AoA sensor was misaligned.

Did MCAS fundamentally fail? Not on the accident aircraft - the algorithm and resulting software did exactly what it was supposed to do with the information it was given. Which leads to the third question - can humans fail safe when it comes to creating algorithms and then creating the software to carry them out? I'd say the answer is mostly yes, but no guarantee.

What I think would work is a force sensor and monitor on the controls that would shout "PULL TOO HARD - RETRIM NOSE UP RETRIM NOSE UP RETRIM NOSE UP" and loop. This could operate outside all other software loops; it could have it's own box independent except for power. Add a 5 second delay against nuisance alerts and it should be good to go. The operation of MCAS wasn't the problem, the problem was allowing the buildup of excessive control forces that prevented the crews from holding the nose up because the plane was out of trim. .This covers all possible reasons for the trim to fail and tells the pilots what the solution is.

[jdawg]

Folks,
this is utter nonsense. A pilot should not have to deliberate trim runaways from activations of MCAS let alone MCAS in error. The complexity is astounding. And for what I ask rhetorically? Money. That's all. Profits.

Ask yourselves, what is the absolute safest course of action to get this bird flying again? Answer, remove MCAS as our friend up in Canada mentioned months ago and segregate the NG from the Max for a period of 5 years or so. Training and crew scheduling both. Five years. After that we can consider the possibility of same type again. But it's really not.

Will the regulators take this route ? It is the safest. I doubt it not only because it makes the Max so distant to the NEO cost wise to operate. Also, I feel Boeing may want to reserve this course of action for the next time a Max kills 200 people. This will be their last resort to give it one more shot. Someone needs to save Boeing from Boeing for Christmas this year.

Happy Holidays All!!!

[568]

This is several questions. The first is whether the software that runs the MCAS algorithm is working correctly and how would the crew know it wasn't. This is the same unsolvable problem that software has always had. The usual approach is to hand an algorithm to a bunch of different software developers to run on different architecture computers and then depend on some other algorithm to decide if the answers are all close enough to select the "truth." This is seen in 2-of-3 voting systems, which are more, but not always, reliable.

The second is how will the crew know that MCAS software is operating correctly, but based on false inputs. This is similar to the first case because the crew isn't ever given raw data; it's all processed through some algorithm so it's back to some voting scheme. The way around algorithms would be to make a selsyn system that moved a mechanical AoA needle on the instrument panel, but it would not help if the needle or the AoA sensor was misaligned.

Did MCAS fundamentally fail? Not on the accident aircraft - the algorithm and resulting software did exactly what it was supposed to do with the information it was given. Which leads to the third question - can humans fail safe when it comes to creating algorithms and then creating the software to carry them out? I'd say the answer is mostly yes, but no guarantee.

What I think would work is a force sensor and monitor on the controls that would shout "PULL TOO HARD - RETRIM NOSE UP RETRIM NOSE UP RETRIM NOSE UP" and loop. This could operate outside all other software loops; it could have it's own box independent except for power. Add a 5 second delay against nuisance alerts and it should be good to go. The operation of MCAS wasn't the problem, the problem was allowing the buildup of excessive control forces that prevented the crews from holding the nose up because the plane was out of trim. .This covers all possible reasons for the trim to fail and tells the pilots what the solution is.Did the NG have a "force sensor" as you described?The MAX cannot be engineered much more differently than the previous models or else "new type rating" will be the only option.

[Loose rivets]

The way around algorithms would be to make a selsyn system that moved a mechanical AoA needle on the instrument panel, but it would not help if the needle or the AoA sensor was misaligned.

Nor would it help the pilot flying hadn't got the basic gut instincts of handling an aircraft that had slipped outside the envelope. Concorde had a huge AoA scale. IIRC, not far left of the flight system. The skippers of that aircraft would I'm sure have put its indications to good use.

I can well see that Concorde pilots needed that information, but I'm not too sure it's needed on ordinary jet transport. Nice to have, but not needed per se. Also, that squitty little indicator on the $80,000 upgrade really doesn't seem adequate.

More 'Shouting' on the flightdeck? Hmmm, not sure about that. 'PULLING TOO HARD.' etc. is needed. I think just a big red placard saying, 'DON'T PULL TOO FAR WHEN THE CONTROLS ARE SQUISHY.' would do it. After all, NO SMOKING worked in the DC3. Oh, wait, perhaps not. I still remember the smell of petrol and the piles of dog-ends in the screen's condensation trough.

Just how much basic flying must be bellowed at the Magenta Line children? From Tiger to my first jet transport, the aircraft let me know by the seat of my pants that the wings were working. The feel of a slow aircraft was chalk and cheese . . . and sphincter-clamping. I just don't understand how anyone could be sitting on mushy air and not know. And yet it's happened, for a horribly long time on the 447. Do modern pilots never take the aircraft to the shake/nudge/push? Is it conceivable they really need that indication, all because a simulator is not capable of generating anything more than a vague illusion of g force?

Later editions of Davis' HtBJ had an impassioned plea for pilots to be able to lay hands on a smaller training aircraft, not least of all because of the above. More costs? The need for this say, once every five years for something so important seems a small price, now this need is emerging from several major losses.

[krismiler]

This clip states at 3min:40secs that an analysis was done which determined that in its present form the MAX could expect a crash every 2-3 years due to MCAS, so no wonder it's been grounded.

https://youtu.be/fetgdmgPQ3M

[568]

Nor would it help the pilot flying hadn't got the basic gut instincts of handling an aircraft that had slipped outside the envelope. Concorde had a huge AoA scale. IIRC, not far left of the flight system. The skippers of that aircraft would I'm sure have put its indications to good use.

I can well see that Concorde pilots needed that information, but I'm not too sure it's needed on ordinary jet transport. Nice to have, but not needed per se. Also, that squitty little indicator on the $80,000 upgrade really doesn't seem adequate.

More 'Shouting' on the flightdeck? Hmmm, not sure about that. 'PULLING TOO HARD.' etc. is needed. I think just a big red placard saying, 'DON'T PULL TOO FAR WHEN THE CONTROLS ARE SQUISHY.' would do it. After all, NO SMOKING worked in the DC3. Oh, wait, perhaps not. I still remember the smell of petrol and the piles of dog-ends in the screen's condensation trough.

Just how much basic flying must be bellowed at the Magenta Line children? From Tiger to my first jet transport, the aircraft let me know by the seat of my pants that the wings were working. The feel of a slow aircraft was chalk and cheese . . . and sphincter-clamping. I just don't understand how anyone could be sitting on mushy air and not know. And yet it's happened, for a horribly long time on the 447. Do modern pilots never take the aircraft to the shake/nudge/push? Is it conceivable they really need that indication, all because a simulator is not capable of generating anything more than a vague illusion of g force?

Later editions of Davis' HtBJ had an impassioned plea for pilots to be able to lay hands on a smaller training aircraft, not least of all because of the above. More costs? The need for this say, once every five years for something so important seems a small price, now this need is emerging from several major losses.Great comments and right "on point".States exactly what I feel about current aircraft handling, training and the sad state of affairs that aviation has become today, as we don't adequately cover fundamental flight principles relating to most type ratings on modern transport aircraft because of time constraints and shorter transition courses.On the many types I flew, we were taught/warned about individual handling characteristics such as Dutch roll, speed brake use, stall tendencies and where the airframe may put you in a precarious situation unless you looked after airspeed, configuration etc.Having read many books about aerodynamics and also the book DP Davies wrote, made me more "aerodynamically aware" and provided me with the knowledge I needed and more!Time for the industry to take a step back and increase training foot prints.

[OldnGrounded]

This clip states at 3min:40secs that an analysis was done which determined that in its present form the MAX could expect a crash every 2-3 years due to MCAS, so no wonder it's been grounded.

https://youtu.be/fetgdmgPQ3M

Well, except that, after doing that analysis, the FAA didn't ground the MAX.

[Water pilot]

I think it is probable that pilot skills are deteriorating (along with pay) but I still fail to see what it has to do with this particular accident. If the plane flew into the ground and the pilots didn't notice because they were too enthralled with their cell phones that would be one thing, but all pilots involved in the three incidents understood what was wrong, the just didn't know what was causing it. Hindsight is 20/20; like viewers of a horror movie we know which door the monster is hiding behind, but the protagonists don't. The surving pilots identified the problem incorrectly but were lucky in that the actions taken to solve the nonexistant problem actually happened to solve the real one.

The poor pilots were at the root of a huge decision tree, and like they are trained to, attempted to find a solution in their procedures and manual. In this case it would have been better had there been no procedures or manual because they wasted time looking for information that was not there. A button that would have easily solved their problem (had they known about MCAS) had been disabled, leaving them having to figure out on the fly a "goldilocks" solution, turn off the electric trim immediately but not before using it to get back enough in trim to use the manual wheels, but not for too long or MCAS will reactivate (as it did.)

This was not a bad play on a football field that we are arguing about, 346 people lost their lives due to an entirely predictable engineering fault.

[jimtx]

This is several questions. The first is whether the software that runs the MCAS algorithm is working correctly and how would the crew know it wasn't. This is the same unsolvable problem that software has always had. The usual approach is to hand an algorithm to a bunch of different software developers to run on different architecture computers and then depend on some other algorithm to decide if the answers are all close enough to select the "truth." This is seen in 2-of-3 voting systems, which are more, but not always, reliable.

The second is how will the crew know that MCAS software is operating correctly, but based on false inputs. This is similar to the first case because the crew isn't ever given raw data; it's all processed through some algorithm so it's back to some voting scheme. The way around algorithms would be to make a selsyn system that moved a mechanical AoA needle on the instrument panel, but it would not help if the needle or the AoA sensor was misaligned.

Did MCAS fundamentally fail? Not on the accident aircraft - the algorithm and resulting software did exactly what it was supposed to do with the information it was given. Which leads to the third question - can humans fail safe when it comes to creating algorithms and then creating the software to carry them out? I'd say the answer is mostly yes, but no guarantee.

What I think would work is a force sensor and monitor on the controls that would shout "PULL TOO HARD - RETRIM NOSE UP RETRIM NOSE UP RETRIM NOSE UP" and loop. This could operate outside all other software loops; it could have it's own box independent except for power. Add a 5 second delay against nuisance alerts and it should be good to go. The operation of MCAS wasn't the problem, the problem was allowing the buildup of excessive control forces that prevented the crews from holding the nose up because the plane was out of trim. .This covers all possible reasons for the trim to fail and tells the pilots what the solution is.

Why don't we just turn MCAS off and when the autopilot is off and the airplane is in the envelope put a force sensor that says "don't pull too hard"? Rhetorical question of course as I can't envision anybody buying that the airframe is safe as is under human pilot control although it seems the autopilot would not be affected. But the above posts regarding freedom of information make me wonder what really is going on with the airframe as even the first AD did not caution about any regime once you successfully applied the runaway trim procedure. I can not make sense of the last BOE 1 flight aware track so I wonder WTF is going on.

[FrequentSLF]

This is several questions. The first is whether the software that runs the MCAS algorithm is working correctly and how would the crew know it wasn't. This is the same unsolvable problem that software has always had. The usual approach is to hand an algorithm to a bunch of different software developers to run on different architecture computers and then depend on some other algorithm to decide if the answers are all close enough to select the "truth." This is seen in 2-of-3 voting systems, which are more, but not always, reliable.

The second is how will the crew know that MCAS software is operating correctly, but based on false inputs. This is similar to the first case because the crew isn't ever given raw data; it's all processed through some algorithm so it's back to some voting scheme. The way around algorithms would be to make a selsyn system that moved a mechanical AoA needle on the instrument panel, but it would not help if the needle or the AoA sensor was misaligned.

Did MCAS fundamentally fail? Not on the accident aircraft - the algorithm and resulting software did exactly what it was supposed to do with the information it was given. Which leads to the third question - can humans fail safe when it comes to creating algorithms and then creating the software to carry them out? I'd say the answer is mostly yes, but no guarantee.

What I think would work is a force sensor and monitor on the controls that would shout "PULL TOO HARD - RETRIM NOSE UP RETRIM NOSE UP RETRIM NOSE UP" and loop. This could operate outside all other software loops; it could have it's own box independent except for power. Add a 5 second delay against nuisance alerts and it should be good to go. The operation of MCAS wasn't the problem, the problem was allowing the buildup of excessive control forces that prevented the crews from holding the nose up because the plane was out of trim. .This covers all possible reasons for the trim to fail and tells the pilots what the solution is.

How would you explain that FAA risk assesment after the Lion crash stated that 15 MAX will crash over the next 45 years?

[Icarus2001]

Waterpilot, can I assume from your handle that you are in fact a pilot?

but all pilots involved in the three incidents understood what was wrong, the just didn't know what was causing it.

If you are you would know that if the aircraft is out of trim a pilot instinctively trims towards a more in trim pressure. The cause is not relevant in maintaining control initially, simply trim as you were taught from lesson one of flying. When it starts to go "out of trim" again the pilot again would trim the other way. This is how they stayed in the air as long as they did. Given they had cautions from rotation they knew they were having a bad day in the office. Call for the trim runaway QRH or unreliable airspeed and keep the nose up and either fly level or climb.

A button that would have easily solved their problem (had they known about MCAS) had been disabled, leaving them having to figure out on the fly a "goldilocks" solution, turn off the electric trim immediately but not before using it to get back enough in trim to use the manual wheels, but not for too long or MCAS will reactivate (as it did.)

The manual electric trim switch would have "easily solved" their initial control problem.

I am not trying to jump on the crew again here, they were faced with all the cacophony of alerts etc but trimming is so fundamental to hand flying that it needs restating that perhaps they do not hand fly enough to gain trim "feel".

[MechEngr]

Why don't we just turn MCAS off and when the autopilot is off and the airplane is in the envelope put a force sensor that says "don't pull too hard"? Rhetorical question of course as I can't envision anybody buying that the airframe is safe as is under human pilot control although it seems the autopilot would not be affected. But the above posts regarding freedom of information make me wonder what really is going on with the airframe as even the first AD did not caution about any regime once you successfully applied the runaway trim procedure. I can not make sense of the last BOE 1 flight aware track so I wonder WTF is going on.

Because one day a maint crew or a hungry rodent will screw something up that has nothing to do with MCAS and Boeing will be blamed for allowing the crash that happens because pilots forget how to trim the plane in their concern for the memory items they did not memorize Having the plane tell them what to do is the only avenue left.

To be fair, the ET302 crew failed to perform the AD or follow the FCOM information or read the Lion Air preliminary crash report. None of that seems to have been learned, if they even bothered reading it. I guess the AD should have said - pedal to the metal and ignore being out of trim is bad. Is that something pilots need to have written for them? The only way out is a plane that tells them to do their job.

[jimtx]

Waterpilot, can I assume from your handle that you are in fact a pilot?



If you are you would know that if the aircraft is out of trim a pilot instinctively trims towards a more in trim pressure. The cause is not relevant in maintaining control initially, simply trim as you were taught from lesson one of flying. When it starts to go "out of trim" again the pilot again would trim the other way. This is how they stayed in the air as long as they did. Given they had cautions from rotation they knew they were having a bad day in the office. Call for the trim runaway QRH or unreliable airspeed and keep the nose up and either fly level or climb.



The manual electric trim switch would have "easily solved" their initial control problem.

I am not trying to jump on the crew again here, they were faced with all the cacophony of alerts etc but trimming is so fundamental to hand flying that it needs restating that perhaps they do not hand fly enough to gain trim "feel".

trim, trim, trim, a mantra to for T-38 pilots a long time ago. Still possibly a mantra in current T-38 training but maybe not necessary in current advanced military jets. But Boeing did not realize who they were selling airplanes to.

[Bend alot]

Because one day a maint crew or a hungry rodent will screw something up that has nothing to do with MCAS and Boeing will be blamed for allowing the crash that happens because pilots forget how to trim the plane in their concern for the memory items they did not memorize Having the plane tell them what to do is the only avenue left.

To be fair, the ET302 crew failed to perform the AD or follow the FCOM information or read the Lion Air preliminary crash report. None of that seems to have been learned, if they even bothered reading it. I guess the AD should have said - pedal to the metal and ignore being out of trim is bad. Is that something pilots need to have written for them? The only way out is a plane that tells them to do their job.
The FAA AD format is a disgrace and needs changing.

The first part is just useless waffle and by the time I actually get to the important stuff, my mind is far away.

Put the relevant stuff first,then the unhelpful bureaucratic rubbish last, including the cost per US aircraft and to US industry - that is not safety it is distracting.

[Three Lions]

Clearly not the place for yet another A v B debate, however please indulge me for one minute. No criticism intended, however an observation.

Taking a much wider view, if a comparison between the 737 Max and the Airbus NEO, then the situation clearly illustrates a clear gulf of concurrent outcome created by the US version of Capitalism and Europe’s more multi nation more socialist based systems. I’m sure everyone agrees that It is generally valuable that the world has very different places and there are positives and negatives worldwide, however the Max story starting with the “Jurassic 737” to present day give a very damning illustration to the capitalist model that many see as the only way.

Simplistically speaking the Airbus NEO, compared to the 737 max indicates the depth of difference both in combined gregarious multi nation effort versus a single nation capitalist creep. On every level from the decisions to continue production of the 737 for decades longer than they should, to the financially decided ongoing design upgrades, the implementation, the regulatory relationship and the following actions since the two fatal accidents there’s a catalogue of missed opportunities to make the right decisions.

The world is watching the next moves at Boeing, the regulator and govt interventions very closely.

The dilemma now for Boeing is that they are down a corridor an just about every door has a sign that says “do not follow this path”. The fact the NEO is doing what it says on the tin and generally quite successful, is actually forcing more pressure across the pond. Not to mention the advancements in the Chinese aviation sector.

It is possible that the problem here isn’t Boeing per se, the specific problem is largely theirs, but under a very prescriptive and financially driven set of circumstances what has been revealed is a weakness in the Capitalist system. Akin to the exhaust port on the Death Star.

It is interesting to see what happens next.

I don’t personally think we will see the Max in the skies for a long time yet. The problem in the current economic model in the US is that the obvious correct path - starting afresh, will possibly lose far too much ground in the manufacture of narrow body medium range jet marketplace

[krismiler]

Had Boeing started work on a B737 replacement in the 1980s, it would have had a modern airframe comparable to the A320 which would have been able to accept upgrades as technology progressed. The A320 after 30 years is still a sound design which could easily go on for another 20 years with a few tweeks here and there. By then it will be 50 years old and the advancements made over this time period will make it worthwhile to a design a completely new type to replace it. Airbus will certainly have had their moneys worth by then.

The idea of Boeing exiting the narrow body market was previously mentioned, the B787 has been very successful for the company and whilst there are a few problems with the aircraft, it might be better to concentrate its resources in this area and address the problems within the company before looking at bringing another type into production, especially with what's going on with the B777X. The Comac C919 would be a worthwhile option for airlines in the meantime as even with the delays the program has had and inevitable issues which will be experienced with a brand new type, it's still way ahead of a B737 replacement being offered.

If Boeing started work on a new narrowbody, in ten years time it could have a state of the art design which would surpass the by then 40 year old A320. Regaining market share from the Chinese would be their main concern as the C919 would be well established and likely substantially improved by then.

Financing all of this would be a major factor as the loss of income from its cash cow together with the compensation payments due and cost of developing a new type could send the company to the wall, unless state support was provided and we know how anti the Americans are about that.

It's the old question of how long you go on throwing good money after bad.

[rog747]

Wonder if they kept the -800 and -900 jigs? Just start building those again.

A moot point - Airline accountants and all the airlines today (and in the future) just want fuel economy and $$savings, hence the fitting of the big new CFM LEAP engines to basically a 737-800, of which they are now the root cause of the unstable MAX air frame, necessitating the MCAS software requirement.

[Vendee]

Did MCAS fundamentally fail? Not on the accident aircraft - the algorithm and resulting software did exactly what it was supposed to do with the information it was given.

Let me remind you that the "S" in MCAS stands for System.

MCAS did fail. The code may have done what it was designed for but the system (which includes the AoA vane) failed.

[martinhogbin]

This is my first post here so I apologise for any errors in the way that I have done so. Advice welcome.

As I understand it the 737 Max cannot be certified to fly at all without MCAS because it does not meet the requirements of FAR 25.203(a) which says "No abnormal nose-up pitching may occur. The longitudinal control force must be positive up to and throughout the stall"

Is there any definitive confirmation of this fact?

If it is NOT true, it would seem to me that Boeing's best way by far to get the planes flying again would be to remove or completely disable MCAS and admit that it is a different aicraft from older 737s and agree to pay for all training required to fly it.

[Lake1952]

Re the Canadian plan, it is exactly what I had proposed sometime in some thread on this board. Kick MCAS out of the aircraft and train for the issues of stick force linearity or pitch up tendencies due to engine location or whatever the aerodynamic aberrations are. If that training requires a new type rating, then so be it.

My LA4-200 Lake Amphibian would pitch down with power and up when you decreased the throttle due to the rear facing engine located more or less at the CG. Exactly the opposite of every other aircraft that I had flown. That aerodynamic tendency was covered on day #1 of training.

[Bend alot]

Martin & Lake how do you propose to comply with the Grandfather rights?

[KCode]

"Seeking Alpha" provides an opinion on the cash flow of the Max program, and supports your comments on the balance of advanced payments versus production costs. Their analysis shows that the advanced payment revenue falls below the production costs (42/M) in Jan.

[clearedtocross]

The fact that B keeps the non-MCAS (raw) pitch-up characteristics a secret leads to the conclusion that those characteristics are much worse than just a mild non-linearity. That is probably also the reason why they multiplied the MCAS action by 4 without telling the FAA (and anybody else).
Drastical pitch up cannot be certified (thank God) as it is bl..dy dangerous even when pilots get told/trained. A commercial jet is not a Lake Amphibian and it is operated on instruments , not on seat of pants VFR operation where a pitch deviation up or down is easily identified and corrected.

[OldnGrounded]

The fact that B keeps the non-MCAS (raw) pitch-up characteristics a secret leads to the conclusion that those characteristics are much worse than just a mild non-linearity.

It certainly leads, at least, to serious skepticism. For some reason, despite lots of people repeatedly asking about this, the data has not been provided.

The Flyers' Rights lawsuit may pry some of it loose.

[Lake1952]

Here are two important parts of the story that we do not know as yet so far as I am aware.
1.) What are the aerodynamic characteristics or aberrations that led to MCAS?
2.) How many times (if any) has the MCAS been activated besides the two Lion and one ET flights? Has MCAS ever been activated when there was no malfunction in the AoA?

Bend a Lot, while I am aware of grandfather rights, I have no idea how much content on the MAX would be verboten or obsolete if a separate type rating was required. Or invent a "sub-type rating". And I have no idea what the type rating has to do with the type certification of the aircraft! Just because an aircraft requires a type rating, why would that affect the type certification of the aircraft?

[PEI_3721]

jimtx, #74 ‘just use the AP’.
This is similar to the calls for FBW; unfortunately the AP argument is flawed.

The Air Data Computers use AoA for corrections. The output of the two ADCs is used by the AP (Flight Guidance Computer) which compares values. If the values of speed / alt disagree ‘by xx’, AoA input error, then the AP will disengage - ‘invalid data’, and the relevant Disagree alerts given.
For Speed and Alt the crew can crosscheck the StBy systems: a checklist item. There is no third AoA, thus the consequential and distracting alerting remains on; no AP available: abnormal conditions #17 (https://www.pprune.org/showthread.php?p=10643705).

The ‘don’t pull too hard’ quip might represent residual problems relating to the design of the trim system and subsequent use without MCAS - see below.

[PHXPhlyer]

MCAS Annunciator

Has anyone proposed an annunciator to show when MCAS is active instead of trying to determine if it is a case of runaway trim or not?
Just a thought.

PP

[PEI_3721]

Icarus2001, #76, following on Water pilot, #72,
The description of trim operation is based on normal operation; relating it to basic flying training. However, the 737 trim system differs from basic training aircraft . The 737 design can inadvertently create bad habits tending to fly the aircraft with trim (Boeing cautions against this).
In normal operation the pilot-aircraft-trim interaction is similar to any other system, the effects of the different design are not readily apparent. However, with large changes in stick position / force, or if the trim malfunctions then the pilot-trim interaction changes (https://www.skybrary.aero/bookshelf/books/2627.pdf).
…
The 737 Max pitch stability is like slice of stale bread, curled up at the edges. MCAS logic applies trim to flatten out the edge bits; small trim changes have a large ‘restorative’ effect, which works.
If large, unwarranted MCAS trim changes occur anywhere in the flight envelope then both aircraft control and restorative trim application is difficult - accidents.
After modification, comparison of sensor input, errors inhibit further MCAS trim movement after one small application; this value will place the aircraft ‘out of trim’. If this occurs in the ‘flat’, centre area of the bread slice, applying trim to flatten a non existent curl might dent or hole the bread causing further problems.
…
Before the Max can return to service the latter case must be assessed as satisfactory - within an agreed range of piloting competence. However, if the small amount of trim from MCAS ‘failure’ creates a false impression of pilot-aircraft-trim, via residual stick force, then the piloting task is increased. How this might apply to manual trim wheel operation is not clear, but evidence suggest its not beneficial.
Similarly application of corrective electric trim to reduce any offset could be masked by the higher stick forces. This situation could be further complicated if the aircraft is flown with trim, small trim blips inadvertently amalgamate to a longer application, applied instinctively in surprising situations - several alerts and distracting stick vibration (see trim system design link above, NB accidents - and recent FlyDubai).

Previous posts https://www.pprune.org/showthread.php?p=10642164 and https://www.pprune.org/showthread.php?p=10643566 assume that all electrical trim operations are inhibited with MCAS inhibit. The rationale is that if the dual FGC is used as the monitor for MCAS, and electric trim and AP trim are within the same box, then the most effective safeguard is to switch everything off. If so, could subsequent pilot evaluation via checklists determine which part of the system has failed and then some parts reinstated; particularly advantageous if electric trim is effective in restoring and continuing safe flight.

The above is influenced by not understanding why the Max trim-inhibit switches differ from the NG, separating elect trim and AP trim (extensive Tech Log discussion); did Boeing expect some aspects to be restorable - is the Max more dependent on electric trim than the NG, thus it is desirable to restore it to reduce workload in abnormal conditions; particularly where trim runaway still has to be considered.
It is in these areas which checklist drills and actions could be generating more certification discussion.
.

[GlobalNav]

Martin & Lake how do you propose to comply with the Grandfather rights?

If by "grandfather rights" you are referring to the Changed Product Rule, I think service history, 2 catastrophic accidents, provides the necessary justification to impose the most current safety standards.

[OldnGrounded]

From Investor's Business Daily, yesterday:

Boeing 737 Max Suppliers, Customers Make Big Moves As Crisis Drags On (https://www.investors.com/news/boeing-737-max-production-halt-moodys-debt-downgraded/)GILLIAN RICH 04:11 PM ET 12/20/2019 (https://www.investors.com/author/richg/)

Boeing 737 Max suppliers Spirit AeroSystems (SPR (https://research.investors.com/quote.aspx?symbol=SPR)) and General Electric (GE (https://research.investors.com/quote.aspx?symbol=GE)) are adjusting their production, and United Airlines (UAL (https://research.investors.com/quote.aspx?symbol=UAL)) canceled 737 Max flights to the start of summer as the grounding drags on longer. Boeing (BA (https://research.investors.com/quote.aspx?symbol=BA)) stock fell.

"This suspension will have an adverse impact on Spirit's business, financial condition, results of operations, and cash flows," said Spirit AeroSystems, which gets about 50% of its revenue from the Boeing 737 Max.

Meanwhile, engine supplier General Electric will boost production of its Leap 1A (https://www.wsj.com/articles/ge-agrees-on-deal-to-build-more-airbus-engines-to-help-offset-max-shutdown-11576860015?mod=hp_lead_pos3) for Airbus (EADSY (https://research.investors.com/quote.aspx?symbol=EADSY)) to help offset lost sales to Boeing during the 737 Max production halt, according to the Wall Street Journal.

Also Friday, United Airlines extended 737 Max cancellations to June, meaning the plane may risk missing another summer travel season. American Airlines (AAL (https://research.investors.com/quote.aspx?symbol=AAL)) and Southwest Airlines (LUV (https://research.investors.com/quote.aspx?symbol=LUV)) have canceled flights through April.

Late Thursday, S&P Global Ratings cut its score by one notch to A- with a "developing" outlook, citing uncertainty over the Boeing 737 Max's return to service, the production halt's supply-chain risks, and the potential long-term damage to the plane's competitiveness.

S&P also downgraded its assessment of Boeing's management to fair from satisfactory.

Late Wednesday, Moody's cut Boeing's debt one notch to A3 while giving it a stable outlook, saying the recently announced production halt will mean Boeing will have to provide additional financial support to many suppliers, increase risk in the production system, and boost customers' claims for compensation, which will lower 737 margins and cash generation "for years to come."

"Moreover, Moody's considers that Boeing's reputation can be adversely affected as the grounding extends and from its governance missteps with broadening social considerations related therefrom, which could have a more lasting impact on the company's business," Moody's added.

Shares fell 1.65% to finish at 328.00 on the stock market today (https://www.investors.com/market-trend/stock-market-today/stock-market-today-market-trends-best-stocks-buy-watch/). Boeing stock remains below its 50- and 200-day lines, according to MarketSmith analysis (https://marketsmith.investors.com/mstool). Spirit AeroSystems lost 1%, while GE ended flat.

[MechEngr]

The fact that B keeps the non-MCAS (raw) pitch-up characteristics a secret leads to the conclusion that those characteristics are much worse than just a mild non-linearity. That is probably also the reason why they multiplied the MCAS action by 4 without telling the FAA (and anybody else).
Drastical pitch up cannot be certified (thank God) as it is bl..dy dangerous even when pilots get told/trained. A commercial jet is not a Lake Amphibian and it is operated on instruments , not on seat of pants VFR operation where a pitch deviation up or down is easily identified and corrected.

There's no drastic pitch-up. How does this get started and why is it repeated? Comparing the plan form to the NG and the differences are difficult to make out.Slight changes in configuration tend not to make drastic changes in performance. More than that, the Max has a thrust line closer to the CG than any other 737, so the pitch coupling should be less or about the same. The larger engine can produce more thrust, but unless the plane is a lot heavier than previous planes the only way to use that thrust is in uncomfortable sea level take-offs or in normal rate departures from high-hot-humid airports. The size increases the coupling of fuel burn to air movement for an increase in thrust specific fuel consumption, aka, fuel efficiency. So, they keep the thrust the same and burn less fuel.

I'm sure the change in factor was not yelled from the roof tops because no one had a fault-tree analysis linking the AoA system to the MCAS output to a definitive emergency outcome. Had they passed along the change in rate without anyone having done the analysis, it would have not raised any questions, just like it did not in the first place. The more aggressive change should have acted to draw the attention of the flight crew to the more rapid pitch trim change and then to the cause of it, rather than being a slower and less obvious one; it appears in the first and second MCAS events that this is exactly what happened. In the third event, the pilots seemed unaware of the change in trim for a relatively long time and did not notice they were left with a large increment.

So far no one has volunteered just how the control forces for pitch mis-trim can be so low so the pitch trim error is unrecognized and so high they cannot be overcome.

[jdawg]

There's no drastic pitch-up. How does this get started and why is it repeated? Comparing the plan form to the NG and the differences are difficult to make out.Slight changes in configuration tend not to make drastic changes in performance. More than that, the Max has a thrust line closer to the CG than any other 737, so the pitch coupling should be less or about the same. The larger engine can produce more thrust, but unless the plane is a lot heavier than previous planes the only way to use that thrust is in uncomfortable sea level take-offs or in normal rate departures from high-hot-humid airports. The size increases the coupling of fuel burn to air movement for an increase in thrust specific fuel consumption, aka, fuel efficiency. So, they keep the thrust the same and burn less fuel.

I'm sure the change in factor was not yelled from the roof tops because no one had a fault-tree analysis linking the AoA system to the MCAS output to a definitive emergency outcome. Had they passed along the change in rate without anyone having done the analysis, it would have not raised any questions, just like it did not in the first place. The more aggressive change should have acted to draw the attention of the flight crew to the more rapid pitch trim change and then to the cause of it, rather than being a slower and less obvious one; it appears in the first and second MCAS events that this is exactly what happened. In the third event, the pilots seemed unaware of the change in trim for a relatively long time and did not notice they were left with a large increment.

So far no one has volunteered just how the control forces for pitch mis-trim can be so low so the pitch trim error is unrecognized and so high they cannot be overcome.
Don't think of it as an issue of "thrust line" nor "thrust to weight" but rather nacelle lift farther forward and higher than the NG. This in fact causes a pitch up moment force behind the curve.

[Fly Aiprt]

There's no drastic pitch-up. How does this get started and why is it repeated? Comparing the plan form to the NG and the differences are difficult to make out.Slight changes in configuration tend not to make drastic changes in performance. More than that, the Max has a thrust line closer to the CG than any other 737, so the pitch coupling should be less or about the same. The larger engine can produce more thrust, but unless the plane is a lot heavier than previous planes the only way to use that thrust is in uncomfortable sea level take-offs or in normal rate departures from high-hot-humid airports.

I'm not sure I'll fully agree with the above.
Small changes in configuration *can* lead to drastic change in flight qualities. Heavy tail buffet in a transport plane has been known to be due to windshield/windshield wipers perturbations, and had to be cured with VG's on top of the cockpit.
Some very little variations in airfoil, washout, dihedral, sweep or mechanical details can trip unwanted flow behaviour.
Boeing said the stability issue was due to the airflow over nacelles and adjacent wing portion rather than thrust line.
Not sure there is a way to foresee mach tuck etc. just by comparing 3-view drawings so I'd say there is more to the 737 stability issue than is officially published.

[OldnGrounded]

There's no drastic pitch-up.

We don't know how pronounced the pitch-up tendency may be. We haven't seen data from testing of the bare airframe.

How does this get started and why is it repeated?

It got started because both Boeing and the FAA have indicated that the size/shape/positioning of the LEAP engines creates additional lift at some attitudes/corners of the envelope and that as a result of that, MCAS is required to provide linear stick force to discourage pilot input bringing the aircraft dangerously close to stall. There is a fair amount of skepticism about the assertion that a system with full authority over the horizontal stabilizer was truly developed and implement merely to control stick force.

Comparing the plan form to the NG and the differences are difficult to make out.Slight changes in configuration tend not to make drastic changes in performance. More than that, the Max has a thrust line closer to the CG than any other 737, so the pitch coupling should be less or about the same. The larger engine can produce more thrust, but unless the plane is a lot heavier than previous planes the only way to use that thrust is in uncomfortable sea level take-offs or in normal rate departures from high-hot-humid airports.

I don't think anyone has suggested (at least in many months) that thrust is the issue here. The issue, as far as we can tell, is increased lift due to the engine nacelles and their position.

[Drc40]

It certainly leads, at least, to serious skepticism. For some reason, despite lots of people repeatedly asking about this, the data has not been provided.

The Flyers' Rights lawsuit may pry some of it loose.


You’re right in it might provide insight but when? Considering how long it takes lawsuits to get moving I can’t see it happening before the FAA makes a decision on the MAX. My guess is most of the speculation here is 100% dead on about the aerodynamic issues with the MAX sans the exact specifics/numbers. I think the best hope we have for answers is the FAA. I would hope they publish a detailed analysis of MCAS and why it’s needed, how it engages, etc when the commentary period opens.

Maybe I’m overly optimistic about the FAA but at this point they have to think 100% transparency is paramount to regaining the lost trust.

On another note, the announcements of shutdowns is now directly impacting many more thousands of workers. Their livelihoods are being compromised, families will have to endure cuts and the number will only increase. This will result in enormous political pressure. Might even become an election issue if this drags on and the out of work numbers continue to rise. The economic impact of Boeing and its ancillary businesses is far and wide. Time is now becoming a factor and I hope it doesn’t cloud the eyes of regulators.

[Phugoidinator]

OldnGrounded, could it also be that higher and more forward position of the nacelles can cause turbulence over the wing at higher angles of attack? Difficult to model or predict what turbulence/loss of laminar flow can do to lift generated by wing.

[fizz57]

So far no one has volunteered just how the control forces for pitch mis-trim can be so low so the pitch trim error is unrecognized and so high they cannot be overcome.

Just to clear up another of your misconceptions (I see that the first has already been addressed), no-one is suggesting that the trim forces are too low and too high under the same flight conditions.

[MechEngr]

Let me remind you that the "S" in MCAS stands for System.

MCAS did fail. The code may have done what it was designed for but the system (which includes the AoA vane) failed.

MCAS met it's system specification and worked according to what the developers expected of it. The expectations were incomplete. I believe I covered the need for the specification to be managed and that humans are involved in that. So, no, the MCAS system did not fail. The development system for MCAS did. Now that a new factor has been added, the new system will likely handle the new factor.

[MechEngr]

Just to clear up another of your misconceptions (I see that the first has already been addressed), no-one is suggesting that the trim forces are too low and too high under the same flight conditions.

It's not a misconception. There have been people suggesting that the pilots could not detect the need to trim; since that need is primarily sensed by control forces, the trim must have been too light to notice. The accident reports suggest the pilots were pulling hard, suggesting the the control forces were high to resist.

So how is it that the pilots did not realize from the control forces in nearly level flight that they needed to trim, particularly on ET302 where the control forces continued to increase with increasing speed. What are those forces?

[MechEngr]

I don't think anyone has suggested (at least in many months) that thrust is the issue here. The issue, as far as we can tell, is increased lift due to the engine nacelles and their position.
No one?

"My LA4-200 Lake Amphibian would pitch down with power and up when you decreased the throttle due to the rear facing engine located more or less at the CG. Exactly the opposite of every other aircraft that I had flown. That aerodynamic tendency was covered on day #1 of training."

Seems like a suggestion that thrust was a factor, so it's not been months.

[Fly Aiprt]

MCAS met it's system specification and worked according to what the developers expected of it. The expectations were incomplete. I believe I covered the need for the specification to be managed and that humans are involved in that. So, no, the MCAS system did not fail. The development system for MCAS did. Now that a new factor has been added, the new system will likely handle the new factor.

Of course we are playing on words here.
Considering that the MCAS was - among other rather vague purposes - meant to provide the same aircraft behavior as the 737NG, one could object that the end result wasn't especially "NG-like", hence the idea that the MCAS failed and has to be changed.
And the change doesn't look like trifle, does it ?

[MechEngr]

Don't think of it as an issue of "thrust line" nor "thrust to weight" but rather nacelle lift farther forward and higher than the NG. This in fact causes a pitch up moment force behind the curve.

I think of increased lift as due to the huge increase in diameter and not the small change to a more forward or higher location.

[Stribeck]

There's no drastic pitch-up. How does this get started and why is it repeated? Comparing the plan form to the NG and the differences are difficult to make out.Slight changes in configuration tend not to make drastic changes in performance.

The fact that engine drag can induce a pitching moment is well known. Below is a quote from the book An Introduction to the Longitudinal Static Stability of Low-Speed Aircraft by F.G. Irving, written in 1966:

"... effects induced by the power plant. If the resultant drag force does not act through the c.g., it produces a pitching moment."
(www: sciencedirect.com/book/9781483200194/an-introduction-to-the-longitudinal-static-stability-of-low-speed-aircraft, from chapter 11 abstract)

Regarding plan form comparison of the 737 NG to the MAX:
The engine drag (NG vs MAX) can be estimated by calculating the drag for a cylinder inclined at 15 degrees AoA with the dimensions of the CFM 56-7b (737 NG) compared to the LEAP-1B (737 MAX). It will indicate a 40 % increase in drag at 200 m/s and 15 degrees AoA for the MAX. The magnitude is in the order of 10's of kN per engine, and unlike the thrust pitch coupling effect mentioned, the drag has the potential to be much more severe as it does not act along the axis of the engine. Consider that drag increases with AoA, as more surface area is exposed, but interestingly due to the high position of the MAX engines, it is likely that the moment arm of the drag will also increase with AoA! I haven't really seen this second point being discussed, but personally I think this is a key that could explain why MCAS was so aggressive.

To summarize: It is clear that the Max engines produce a significantly increased drag compared to the NG, and it is clear that this causes a pitching moment that can increase non-linearly with AoA. How bad is it? It will depend on the exact relation between the aircraft CG and the nature of the engine drag. Only Boeing can answer this question, and the fact that they have declined to do so for about 1 year tells me that it is probably pretty bad...

[Longtimer]

Not enough info released yet to say for sure, could also have been a mistake in a timing driven script that had an incorrect value, in hotel layover terms : clock correct, wrong alarm time set.
Either way not a good day for Boeing.

I almost missed a flight once due to the classic AM/PM mistake, always use 2 alarms for anything critical since then.

Now back to our regularly scheduled "not rocket science" 737/MAX programming.
simple fix, program all of your time devices in 24hr clock.

[Fly Aiprt]

I think of increased lift as due to the huge increase in diameter and not the small change to a more forward or higher location.

According to Boeing, it is due to the change for an higher and more forward position.
Of course this is caused byt the engine larger diameter and short landing gear.
Worthy of note, the 320 Neo has no issues, though its engine have a larger diameter yet.

[EvaDestruction]

And so we have here an excellent discussion by very knowledgeable individuals as to how best to solve aerodynamic and design issues that should have been discussed by boards of engineers at Boeing many years ago. If Boeing had played by the rules and certified it as a new type, if Boeing had been honest and professional. Which it wasn't.

[KelvinD]

Declaration: I am not a pilot! (Have flown gliders only)
Having got that out of the way, I have to ask a question that has been bothering me since this issue first arose: From what I read here, the MCAS problems arise from erroneous AoA indications (plus the obvious follow ons such as the correct action to take etc). Why does the only indication of AoA have to be from a fallible instrument stuck outside on the airflow? Outside of aviation, there are many devices that can perform the same function, such as inclinometers etc, either working from a bubble indication or an object floating in a liquid. Why can a pilot not have an instrument, mounted inside the cockpit, that will give him an indication of AoA, regardless of what the airflow over an outside instrument tells him., At least, he would then have the opportunity to think about whether or not something is wrong.

[MechEngr]

Declaration: I am not a pilot! (Have flown gliders only)
Having got that out of the way, I have to ask a question that has been bothering me since this issue first arose: From what I read here, the MCAS problems arise from erroneous AoA indications (plus the obvious follow ons such as the correct action to take etc). Why does the only indication of AoA have to be from a fallible instrument stuck outside on the airflow? Outside of aviation, there are many devices that can perform the same function, such as inclinometers etc, either working from a bubble indication or an object floating in a liquid. Why can a pilot not have an instrument, mounted inside the cockpit, that will give him an indication of AoA, regardless of what the airflow over an outside instrument tells him., At least, he would then have the opportunity to think about whether or not something is wrong.

Angle of attack is independent of pitch and acceleration. Inclinometers and bubbles indicate the direction of local acceleration. This is only reliable if the vehicle they are in cannot accelerate and add or subtract from the acceleration due to gravity. The closest one can get is to differentiate (mathematical process) to determine the path and compare that to the apparent pitch alignment to that path. Even then it's not a certainty as that depends on the air being stationary and uniform, which it usually isn't.

Essentially the only way to account for the local relative wind's likely effect on the aerodynamics of the plane is to use an instrument that is directly affected by the local relative wind. Some less-direct aerodynamic sensors do exist, such as laser Doppler meters that measure the effect of the local wind on dust particles in the air, and I think there are hot-wire probes that detect the thermal convective characteristics, but those are more prone to getting broken and are much more expensive their fragility.

[MechEngr]

According to Boeing, it is due to the change for an higher and more forward position.
Of course this is caused byt the engine larger diameter and short landing gear.
Worthy of note, the 320 Neo has no issues, though its engine have a larger diameter yet.

The 302 Neo constantly adjusts the stabilizer trim because it operates in MCAS 100% of the time, they just don't call it MCAS. It hasn't had any problems because it is not being sold to airlines which need to directly transfer 737 NG pilots to new seats. As a result they don't have the 737 cockpit automation, for good or bad, and don't fit into the ground-handling system the 737 does.

[kontrolor]

Guardian article, (https://www.theguardian.com/business/2019/dec/21/pressure-on-faa-to-approve-737-max-jets-backfires-for-boeing) doesn't look good. I think Boeing must change its corporate culture. It went south after merging with McDonnell Douglas. Toxic culture spilled all over. And Boeing should feel the consequences of their greed. Because it was pure corporate greed that drove to this situation. I hope EASA will be even tougher on MAX. This is just insane - Boeing makes an airplane with fatal flaw, the consequences of which could even be mathematicaly proven (crash every 2-3 years) and that even didn't bother them. I hope the managment will be sued big time and fired sans golden parachutes this time. It is high time that strictier regulation is put over whole industry. This time everything went too far.

[OldnGrounded]

You’re right [that the Flyers' Rights lawsuit] might provide insight but when? Considering how long it takes lawsuits to get moving I can’t see it happening before the FAA makes a decision on the MAX.

That might be true, but this isn't the sort of litigation that *usually* runs on forever, at least not at the district court stage. The Flyers' Rights folks are arguing that the prompt release of the information is critical, precisely because of the (presumably) impending FAA action. They're just seeking an order from the court requiring the agency to release the information as required by FOIA. It might not take too long.

And the FAA will be in a really gigantic mess if they approve return to service while withholding the data from independent experts and something bad happens. At least some people there probably understand that.

[OldnGrounded]

No one?

"My LA4-200 Lake Amphibian would pitch down with power and up when you decreased the throttle due to the rear facing engine located more or less at the CG. Exactly the opposite of every other aircraft that I had flown. That aerodynamic tendency was covered on day #1 of training."

Seems like a suggestion that thrust was a factor, so it's not been months.

Well, perhaps I was insufficiently careful with my wording, but, seriously, if you read the very long record of these threads, it will be clear to you that what I wrote is a reasonable description of the development of the prevailing understanding around here.

[OldnGrounded]

OldnGrounded, could it also be that higher and more forward position of the nacelles can cause turbulence over the wing at higher angles of attack? Difficult to model or predict what turbulence/loss of laminar flow can do to lift generated by wing.

I'm sure it's generally possible, but determining whether that could apply to the MAX is way beyond my aerodynamic knowledge.

[Grebe]

The length of this thread and its previous makes it difficult to refer to specifics and what the past and current semi- technical discussions have been- since most of the current questions have long since been addressed- discussed- ad naseasum

So I'm going to post a few links to different blogs- which if 0ne takes the time to read and figure out how to go to previous and following on the site(s) listed will at least provide mostly rational discussion.




https://www.satcom.guru/2019/10/flawed-assumptions-pave-path-to-disaster.html

https://leehamnews.com/2019/11/29/bjorns-corner-analysing-the-lion-air-jt610-crash-part-5/


https://www.moonofalabama.org/2019/05/boeing-737-max-crash-reveals-a-severe-problem-with-older-boeing-737-ngs.html



https://www.pprune.org/tech-log/621490-b737-max-threads.html


And from a long ago post somewhere in prune news and rumours one can find the below



[QUOTE]



From ??? in pprune rumours

Regarding the trim wheels: When the NG was being introduced, I happened to be the Lead Engineer in charge of them and a whole lot of other stuff. There were some issues. The new display system created a pinch point between the dash and the wheel. We had to make the wheel smaller. And the new trim motor resulted in the wheel, which is directly connected to the stabilizer by a long cable, springing back when electric trim was used. It was an undamped mass on the end of a spring. We had to add a damper.

Result: Depending on the flight conditions, the force to manually trim can be extremely high. We set up a test rig and a very fit female pilot could barely move it.

As I said, I'm glad I'm no longer there."





And re stick force found

https://www.satcom.guru/2019/03/taking-next-steps-while-awaiting-on.html

........ This aspect is essential in ensuring the pilot does not have to push the yoke to stop the plane from pitching up, which violates positive stick force per g as required in 25.255....

... stick force per g must be positive . ..

[jdawg]

I think of increased lift as due to the huge increase in diameter and not the small change to a more forward or higher location.
Understood. But the more forward nacelle during high angles of attack is a longer lever arm. Additionally the higher up on the pylon the nacelle is mounted also contributes a longer lever arm pitch up moment at high aoa. Again it's the the lift from air impinging on the nacelle as well as the lift from the nacelle.

[medod]

Ahhh so it’s Title 14 Part 25.255 the MAX airframe falls foul of. Spent ages looking through Part 25 yesterday but didn’t read that section (Out-of-trim characteristics).

Whatever the exact reasons, the MAX’s big ass engines mean it fails 25.255 without MCAS. That is why I believe the MAX will never fly again in commercial service with less than three AoA vanes.

[OldnGrounded]

Whatever the exact reasons, the MAX’s big ass engines mean it fails 25.255 without MCAS.

Yup. That's it.

That is why I believe the MAX will never fly again in commercial service with less than three AoA vanes.

There is, at least, a serious argument that it shouldn't (or without some synthetic third AoA input).

[jimtx]

The length of this thread and its previous makes it difficult to refer to specifics and what the past and current semi- technical discussions have been- since most of the current questions have long since been addressed- discussed- ad naseasum

So I'm going to post a few links to different blogs- which if 0ne takes the time to read and figure out how to go to previous and following on the site(s) listed will at least provide mostly rational discussion.


[QUOTE]

https://www.satcom.guru/2019/10/flawed-assumptions-pave-path-to-disaster.html

https://leehamnews.com/2019/11/29/bjorns-corner-analysing-the-lion-air-jt610-crash-part-5/


https://www.moonofalabama.org/2019/05/boeing-737-max-crash-reveals-a-severe-problem-with-older-boeing-737-ngs.html



https://www.pprune.org/tech-log/621490-b737-max-threads.html


And from a long ago post somewhere in prune news and rumours one can find the below






And re stick force found

https://www.satcom.guru/2019/03/taking-next-steps-while-awaiting-on.html

........ This aspect is essential in ensuring the pilot does not have to push the yoke to stop the plane from pitching up, which violates positive stick force per g as required in 25.255....

... stick force per g must be positive . ..

I think the slope of the stick force per G is positive. It's just not linear in the regime they are concerned with.

[Loose rivets]

Fitting a third vane?

You can see how hard it would be to add another AoA vane. It must not disturb the other sensors and they must not disturb it. When a good place is found in airflow analysis, there's probably a complex object behind the metal. When a final decision is made, the wiring to the black box will be a major undertaking when multiplied by the hundreds of existing MAX's.

When the wiring is in, the black box will not have the slightest idea what to do with the information. It has no plughole labelled 'Additional Sensors'. I have a bad feeling it would not even have the capability of being modified to take a new input. You can see where this is going: not a chance of Boeing accepting this mod without one hell of a fight. AoA synthesis would be easier, and then, that information has to go somewhere.

Picture pulled off a Seattle Times post from October. It says MAX, but not sure. However it allows my point to be made.



https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/1340x2000/sensors_b682b4cdc65f6bf7d08a5f853567c4c8c1cfa5f5.jpg

[OldnGrounded]

[QUOTE=Grebe;10645167]

I think the slope of the stick force per G is positive. It's just not linear in the regime they are concerned with.

Here it is:

§ 25.255 Out-of-trim characteristics.

[. . .]

(b) In the out-of-trim condition specified in paragraph (a) (https://www.law.cornell.edu/cfr/text/14/25.255#a) of this section, when the normal acceleration is varied from + 1 g to the positive and negative values specified in paragraph (c) (https://www.law.cornell.edu/cfr/text/14/25.255#c) of this section -

(1) The stick force vs. g curve must have a positive slope at any speed up to and including VFC/MFC; and

(2) At speeds between VFC/MFC and VDF/MDF the direction of the primary longitudinal control force may not reverse.

[DieselOx]

I think the slope of the stick force per G is positive. It's just not linear in the regime they are concerned with.

Why do you think that? I hear a lot of people speculating that's the case, but no one has has definitively proven that one way or the other, directly from any data so far publicly available.

Boeing's statement is basically MCAS is an augmentation to maintain proper stick force, but as far as I remember, reading everything here and everywhere else, they very carefully never say where they start from.

Someone fly the plane w/o MCAS and report back. Then I'll believe it.

[Pilot DAR]

I was right, and then left seat, for Transport Canada Aircraft Certification flight testing yesterday. The test pilot and flight test engineer, were extremely thorough. The FTE explained to me after the day's test flying that because of the concern that some compliance was not truly demonstrated for the MAX certification, Transport Canada was not going to allow themselves to be caught out not having thoroughly flying tested one of their programs, if another authority later inquired.

At least, with Transport Canada, the pendulum has swung back (and I suspect with EASA too). Where, in the past, they might have accepted my word as an aircraft certification delegate, now they want to see for themselves, 'cause they're on the hook for documenting the finding of compliance. Considering the MAX certification concerns, I can certainly see their point!

[averow]

You are correct Murphy. I use three alarms in different devices for critical events (like getting to work on time.) I haven't been late for twenty years now, and yes my colleagues notice.

[jimtx]

Why do you think that? I hear a lot of people speculating that's the case, but no one has has definitively proven that one way or the other, directly from any data so far publicly available.

Boeing's statement is basically MCAS is an augmentation to maintain proper stick force, but as far as I remember, reading everything here and everywhere else, they very carefully never say where they start from.

Someone fly the plane w/o MCAS and report back. Then I'll believe it.

I would agree that Sully should fly the plane without MCAS and report back. I'm sure the Boeing test pilots have been fitted with a chastity belt and you won't hear anything from them about their opinion about whether the airplane should not be flown without MCAS. I'm assuming that the "§25.175 Demonstration of static longitudinal stability." requirements of a "stable" (what most of us were calling linear) stick force curve were not met in flight test in rarely visited flight regimes and they thought they had to pencil whip that. I would have argued about what was a stable stick force curve if I thought the bare airframe would not give a normal pilot any trouble. They decided to pencil whip it rather than bite the bullet and are continuing to let the tail wag the dog. But I'm with you, we are babes in the woods until Boeing and FAA clear up some stuff.

[Nomad2]

You know, Boeing clearly have the expertise and experience to build the best passenger jet in this sector of the market, so why have they persisted all this time with ever more modified 737s?

Plainly, the original design was good, and it could stand some enlargement, but with any design there comes a point where the possibilities for modification and improvement are exhausted. Looking at some of the larger NGs or the P-8 shows how far they came- and safely.

But adding the LEAP engines was clearly a step too far. The 737 really needed a redesign into what would effectively be a new aircraft to accommodate the new engines, so why wasn't it done?

If this jet is to return to the skies, it should get what it needs- new undercarriage, probably the wing repositioned on the fuselage, the engines where they should be, and many other changes. It will be too much of a change for the existing jets, but the MAXes could probably be modified into useful 737 variants using normal engines.

Boeing need to get a grip. There's more to a company than just money and profit- there's also product.

They should do what they know, better than anyone, needs done.

Accept the sunk losses, repurpose the MAXs' into something else.

Start on their A320, GTF engined competitor from scratch, restore their reputation, and make a damn good job of it.

Go on to sell thousands of them, and make a fortune.

edit. The MAX has LEAP engines, not GTF. Although both are much bigger and powerful than previously fitted power plants.

[Grebe]

You know, Boeing clearly have the expertise and experience to build the best passenger jet in this sector of the market, so why have they persisted all this time with ever more modified 737s?

Plainly, the original design was good, and it could stand some enlargement, but with any design there comes a point where the possibilities for modification and improvement are exhausted. Looking at some of the larger NGs or the P-8 shows how far they came- and safely.

But adding the GTF engines was clearly a step too far. The 737 really needed a redesign into what would effectively be a new aircraft to accommodate the new engines, so why wasn't it done?

If this jet is to return to the skies, it should get what it needs- new undercarriage, probably the wing repositioned on the fuselage, the engines where they should be, and many other changes. It will be too much of a change for the existing jets, but the MAXes could probably be modified into useful 737 variants using normal engines.

Boeing need to get a grip. There's more to a company than just money and profit- there's also product.

They should do what they know, better than anyone, needs done.

Accept the sunk losses, repurpose the MAXs' into something else.

Start on their A320, GTF engined competitor from scratch, restore their reputation, and make a damn good job of it.

Go on to sell thousands of them, and make a fortune.


If this jet is to return to the skies, it should get what it needs- new undercarriage, probably the wing repositioned on the fuselage, the engines where they should be, and many other changes. It will be too much of a change for the existing jets, but the MAXes could probably be modified into useful 737 variants using normal engines

Sorry Charlie - doesn't work that way in real airplanes.....

[Superpilot]

When the wiring is in, the black box will not have the slightest idea what to do with the information. It has no plughole labelled 'Additional Sensors'. I have a bad feeling it would not even have the capability of being modified to take a new input.

It is possible to daisy chain data. There does not need to be a one to one relationship between sensor and input. You simply offset the values from one sensor by a known constant so it can be decoded later (in software) as coming from a separate source. This would be a major weight saving too. Acceptable to the FAA? Who knows...

[fizz57]

Why do you think that? I hear a lot of people speculating that's the case, but no one has has definitively proven that one way or the other, directly from any data so far publicly available.

Boeing's statement is basically MCAS is an augmentation to maintain proper stick force, but as far as I remember, reading everything here and everywhere else, they very carefully never say where they start from.

Someone fly the plane w/o MCAS and report back. Then I'll believe it.

The non-linearity issue was brought up by FCEng84 way back when the whole thing started in one of the now-closed threads. It is the stick force reversal and instability that are speculations, and came later.

That poster was usually a very reliable and well-informed source. Unfortunately he hasn't posted for a very long time (probably the price for being too well-informed).

[MechEngr]

You know, Boeing clearly have the expertise and experience to build the best passenger jet in this sector of the market, so why have they persisted all this time with ever more modified 737s?

Plainly, the original design was good, and it could stand some enlargement, but with any design there comes a point where the possibilities for modification and improvement are exhausted. Looking at some of the larger NGs or the P-8 shows how far they came- and safely.

But adding the GTF engines was clearly a step too far. The 737 really needed a redesign into what would effectively be a new aircraft to accommodate the new engines, so why wasn't it done?
...

Because that's not what their customers wanted. They wanted a 737 that their pilots could easily move to, that their gate equipment would work with, that their mechanics were qualified to work on and had experience working with. A ground-up new airplane would have none of that, particularly if the landing gear got longer. If that's not what they wanted the purchasing airlines could go with Airbus and start some segments of their business from scratch.

It's not clear the new version is a step too far. A lack of imagination seems to have prevented anyone from noticing the potential for disaster, even after the first crash when all the variables were laid out, plain to see. This is the first foray into a semi-aided system for a generally manually controlled plane. Unlike FBW, it doesn't require scrutiny of every detail of its function merely to fly. The autopilot was essentially unaffected by the engine change and defers to the pilots when a problem happens. MCAS sits in a similar position to the driving systems being used on cars that keep lanes and try to avoid collisions; they work but, since they depend on the operator, when there's an overlap of authority there's a much more complex potential interaction.

[Bend alot]

even after the first crash when all the variables were laid out, plain to see.

Cummon - plain to see!

There are still many secrets - after the first crash very little was disclosed and what was was in tongues in the FAA AD that lacked much information that could have been included.

Something like we expect more than 10 aircraft to crash over the next thirty years due to the MCAS system, based on known information relating to the first crash.

[MechEngr]

It is possible to daisy chain data. There does not need to be a one to one relationship between sensor and input. You simply offset the values from one sensor by a known constant so it can be decoded later (in software) as coming from a separate source. This would be a major weight saving too. Acceptable to the FAA? Who knows...

The sensor is a resolver which itself is has multiple transformers. They have a precision circuit to drive them and a complicated circuit to read them. They aren't capable of being daisy chained as the processing is done in the ADIRU, which has one input for that resolver. Look up how a position resolver is operated; they are a nearly ideal sensor with no wear components required and no friction from making measurements, unlike potentiometers, and continuous readings, unlike encoders. They make up for it in the support electronics, though they can be used in a selsyn configuration, which can be useful for remote analog sensing, though synchros are more likely to be used as selsyns..

[Nomad2]

Grebe.
It may not be how things happen at Boeing, North America- but it's exactly how things DO happen at Boeing Brazil.
The GTF engined 190 E2 has a new undercarriage, with a repositioned wing, the engines where they should be, and many other changes- so maybe it's about time things changed in the US, Charlie?

MechEngr.
The Embraer 190 E2 carries a common type rating with the original E190, despite being effectively a completely different aeroplane and properly redesigned to accommodate the fuel efficient (and jolly powerful) GTF motors.
I agree, that's what the customers want....
What they probably didn't want is a re-engined 737 that they are not permitted to operate.

[MechEngr]

Cummon - plain to see!

There are still many secrets - after the first crash very little was disclosed and what was was in tongues in the FAA AD that lacked much information that could have been included.

Something like we expect more than 10 aircraft to crash over the next thirty years due to the MCAS system, based on known information relating to the first crash.

That report came out while Boeing was working on new software to describe what would happen if the full fleet, about 10X more planes, with unchanged software, were to fly. Same thing happens when a car recall is made; but the predicted result never happens because most cars get the recall done and the rest get taken out of service for some other reason. Since 100% of the planes were intended to get the 'recall' done to update the software the report was a gross, though necessary, exaggeration.

What information available now was not in the preliminary Lion Air report that made a difference? The Emergency Airworthiness Directive and associated AD does not leave much to the imagination, and anyone flying a Max should have read that preliminary accident report as if their life depended on it. In addition Boeing issued their own guidance directly to Max operators, with further details, such as that it operates only in flaps-up flight. They also issued a separate bulletin, number TBC 19, that described the 10 second run and then retrigger on any trim change with a 5 second delay.

The only secret that is left is that if the maximum velocity is exceeded with the plane far out of trim that the trim wheels are too hard to turn. But if the initial guidance is used, the plane is never out of trim and never outside the velocity envelope, so planning for that is unexpected.

I'd say it was up to every operator to carefully examine all the data about a crash involving their same type equipment and understand whether their training and other preparations were sufficient to deal with the situation. Had that happened the difficulty in using the trim wheels might have been exposed; certainly Mentour Pilot did his part and CP Bernd Kai von Hoesslin seems to have fought hard to do so as well, but it didn't seem to occur to Max operators to push back and go public with any flaws in the published documentation.

[Bend alot]

MAX operators just like the shinny brochure parts.

The FAA AD on the matter was and is absolute rubbish, of the same level of the original certification of the MAX - just how Boeing told them it will say.

The FAA does not have a massive credibility issue for non genuine reason/s. They blew it during the start, after the first accident, after the second and now the non reply to the Freedom Of Information request - that request was excluding the FAA and its discussions and decisions documents. It was a genuine request that if nothing to hide would have gone along way to regaining public trust.

I went to the local mint the other day and said I am a customer I buy your gold bars but they are too small. I will remain a customer if you make them bigger, but you must not be more expensive than the local bank. That's what customers want.

P.S. given half the pilots did "unexpected" things in the MAX test sims the other day with all the 20/20 of the last year - The prelim report and the AD were based on incorrect assumptions for many/most crews.

[MechEngr]

Grebe.
It may not be how things happen at Boeing, North America- but it's exactly how things DO happen at Boeing Brazil.
The GTF engined 190 E2 has a new undercarriage, with a repositioned wing, the engines where they should be, and many other changes- so maybe it's about time things changed in the US, Charlie?

MechEngr.
The Embraer 190 E2 carries a common type rating with the original E190, despite being effectively a completely different aeroplane and properly redesigned to accommodate the fuel efficient (and jolly powerful) GTF motors.
I agree, that's what the customers want....
What they probably didn't want is a re-engined 737 that they are not permitted to operate.

Not sure where you are going with this. The E190 customers aren't 737 customers. Looks like there are under 600 190s in the world and orders for less than 40 E2s so far.
There are about 7000 NGs and were orders for about 5000 Max's. That's one to two orders of magnitude greater investment in 737 operations.

I see it's a FBW which covers a multitude of sins, so the comparison to the 737 is weak. " The E2 have 75% new parts" which would cripple logistics for an airline that had thousands of the old ones to maintain and were looking to expand with new ones; not a problem for the E190 series. (quote per the Wikipedia E2 page)

It would have been an impossible sell for Boeing to make a plane that did not fit existing operations. I guess we'll see if Embraer can sell in quantity.

[MechEngr]

MAX operators just like the shinny brochure parts.

The FAA AD on the matter was and is absolute rubbish, of the same level of the original certification of the MAX - just how Boeing told them it will say.

The FAA does not have a massive credibility issue for non genuine reason/s. They blew it during the start, after the first accident, after the second and now the non reply to the Freedom Of Information request - that request was excluding the FAA and its discussions and decisions documents. It was a genuine request that if nothing to hide would have gone along way to regaining public trust.

I went to the local mint the other day and said I am a customer I buy your gold bars but they are too small. I will remain a customer if you make them bigger, but you must not be more expensive than the local bank. That's what customers want.

P.S. given half the pilots did "unexpected" things in the MAX test sims the other day with all the 20/20 of the last year - The prelim report and the AD were based on incorrect assumptions for many/most crews.

Since there's no indication of what the current list is like or how they scored the performance of the pilots, however since every simulation was handled successfully, then it's possible the instructions are now so detailed they required more time to memorize than was given.

The gold bar analogy is terrible, but it is right - if the mint can do that they will undersell the competition; that's how the market generally works.

The AD is not issued in a vacuum. It does not include a complete how-to training course in learning to trim a plane. That was assumed to be trained into pilots, but it is clear the Ethiopian pilots did not do this and it is unclear why they did not do this. They did, however, ignore the clear admonition to never turn the trim enable switches back to enable if they had been disabled. The AD covered that and that allowed the last trim application the pilots did not counter.

[SLF3]

If MCAS was ‘just’ to get a common type certificate Boeing would have bit that bullet by now and the Max would be flying. No one goes $9 billion in the hole to avoid a training bill.

The only plausible explanation for the time it has taken to fix this is that the aerodynamics without MCAS are fundamentally flawed, likely because the engines are to far forward and to high on the wing.

The JATR and EASA both want to see the unaugmented aerodynamics. If after a year they have not seen them, or have seen them and won’t accept them, the Max is likely not certifiable. The Canadians have pretty much publically called Boeing bluff (‘if it’s OK without MCAS, certify it without MCAS’).

The political pressure to certify the Max is immense. The technical case not to must be compelling.

[clearedtocross]

If MCAS was ‘just’ to get a common type certificate Boeing would have bit that bullet by now and the Max would be flying. No one goes $9 billion in the hole to avoid a training bill.

The only plausible explanation for the time it has taken to fix this is that the aerodynamics without MCAS are fundamentally flawed, likely because the engines are to far forward and to high on the wing.

The JATR and EASA both want to see the unaugmented aerodynamics. If after a year they have not seen them, or have seen them and won’t accept them, the Max is likely not certifiable. The Canadians have pretty much publically called Boeing bluff (‘if it’s OK without MCAS, certify it without MCAS’).

The political pressure to certify the Max is immense. The technical case not to must be compelling.

Fully agree, SLF3. And I guess thats also why FAA did not comply with the request to forward the re-certification documents: because they have nothing that comes even close to it.

[pilotmike]

Declaration: I am not a pilot! I have to ask a question that has been bothering me since this issue first arose: Why does the only indication of AoA have to be from a fallible instrument stuck outside on the airflow?
Because that is how to measure AoA.

Declaration: I am not a pilot! Outside of aviation, there are many devices that can perform the same function, such as inclinometers etc, either working from a bubble indication or an object floating in a liquid.
Because that would measure acceleration, whether gravity or acceleration of the aircraft, not AoA as required.

Declaration: I am not a pilot! Why can a pilot not have an instrument, mounted inside the cockpit, that will give him an indication of AoA, regardless of what the airflow over an outside instrument tells him.,.
You appear to be confusing the instrument (display) inside the fight deck, and the sensor from which the indication is derived. These are usually located outside of the flightdeck for most instruments.

[Fly Aiprt]

You know, Boeing clearly have the expertise and experience to build the best passenger jet in this sector of the market, so why have they persisted all this time with ever more modified 737s?

The MCAS debacle and other issues with quality clearly show a lack of expertise, as is the way B management handles the crisis.
Understandably it may be hard to envisage it, but there is a possibility that Boeing no longer has the expertise and experience to build acceptable passenger jets.
Those who designed the last successful Boeing jets are now retired, and there have been reports that Boeing clearly laid off senior engineers years ago.
If that is true, where would the new engineers get their experience and expertise from ?

[turbidus]

You can see how hard it would be to add another AoA vane.

They could add a common pitot/AoA vane where the current pitot is?
https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/600x420/142381_800_ded056607a41f210fda685b84a65c1f598c2ef5f.jpg

I was right, and then left seat, for Transport Canada Aircraft Certification flight testing yesterday. The test pilot and flight test engineer, were extremely thorough. The FTE explained to me after the day's test flying that because of the concern that some compliance was not truly demonstrated for the MAX certification, Transport Canada was not going to allow themselves to be caught out not having thoroughly flying tested one of their programs, if another authority later inquired.

​​​​​​​Nice! Are you testing the 'rollercoaster" technique? The previous BOE1 appeared to be...

[Peter H]

Declaration: I am not a pilot! (Have flown gliders only)
... Why does the only indication of AoA have to be from a fallible instrument stuck outside on the airflow? ...

A recurrent question, not least because of the ready availability of both GPS and high-quality inertial-frame-of-reference devices.

But the AoA is defined as the angle between the wing and the mass of air in which the plane is flying. Here are pictures of 4 planes
just about to stall (from https://www.apstraining.com/resource/whats-the-big-deal-about-angle-of-attack/) (https://www.apstraining.com/resource/whats-the-big-deal-about-angle-of-attack/)

https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/337x283/image01311_1012cf0ea758b3c5fcf1183e27f89af56f792506.gif
... and the velocity shown here is relative to the local air-mass, not something you could measure with GPS.

Smoke-tails at acrobatic displays confirm that AoA and attitude may have startlingly little relationship to each other, as in this eye-candy AOA versus pitch (https://www.pprune.org/tech-log/616969-aoa-versus-pitch.html#post10353314)

PS In clear air it might be possible to measure the the relative velocity of the air to the plane by some laser-based optical device. However
in cloud, fog, heavy rain, icing-conditions, ... no way. (After AF447 they considered this avenue for airspeed measurement.)

[krismiler]

The MAX has a modern wing and the latest fuel efficient engines, it's a pity Boeing didn't bolt them onto a new fuselage instead of a relic from the 1950s first generation of jet transports.

If the MAX can't be recertified then the supply chain may have a hope with the C919 which has a large amount of US sourced content. If the Chinese ramp up production to fill the void then there will be considerable demand for engines, APUs, FMS etc to be filled, keeping American workers in jobs. Limiting the contagion from spreading much beyond Boeing itself and the factory towns which produce the MAX would be preferable to the ripple through effect where shops are forced to close because workers lose their jobs at factories which supply components to larger manufacturers in different states which in turn supply Boeing.

Even if some authorities accept a fix, the Chinese may demand substantial trade concessions in other areas in exchange for approving the aircraft. If these aren't forthcoming they could make any acceptance conditional on impossible terms such as a completely new flight control system or ban the aircraft all together.

[Lake1952]

Pilots, Not the Plane, Keep the Boeing MAX GroundedAfter the tragedies, pilots will be expected to know less and religiously follow checklists more.https://s.wsj.net/public/resources/images/B3-BI571_jenkin_AM_20180807123815.jpg (https://www.wsj.com/news/author/5469)ByHolman W. Jenkins, Jr.Dec. 20, 2019 5:18 pm ET

https://images.wsj.net/im-138558?width=620&size=1.5

A Boeing 737 MAX in Renton, Wash., April 13, 2017. Photo: Ted S. Warren/Associated Press
Ghosts and goblins are keeping the troubled new Boeing (https://quotes.wsj.com/BA) 737 MAX out of the air now. So much so that the company this week announced it will stop an assembly line that was producing dozens of planes a month to be stored in parking lots.

After the first MAX crash took place in Indonesia in late 2018, the U.S. Federal Aviation Administration decided to keep the plane flying. Consternation followed a Journal report (https://www.wsj.com/articles/internal-faa-review-saw-high-risk-of-737-max-crashes-11576069202?mod=article_inline) last week showing that at the time the agency anticipated a MAX crash rate three times that of comparable airplanes. In the FAA’s defense, it also presumed that Boeing would fix the MAX’s faulty flight-control software well before another crash occurred. In the meantime, impressed upon pilots would be that any glitch could be quickly neutralized by throwing a couple of prominent switches.Which makes all the more urgent understanding why the next crash, involving Ethiopian Airlines Flight 302, happened just months later. For the last three minutes of what was a six-minute flight, the offending software system, as per Boeing’s instructions after the Indonesia crash, was disabled. Yet the pilots never cut takeoff thrust despite a loud clacker warning that their airspeed was exceeding the plane’s design limit. With so much force acting on the plane’s control surfaces, they were unable, as Boeing’s new checklist also specified, to move the trim wheel manually to correct the nose-down trim imposed by the faulty software.

They didn’t use the three minutes to heed the clacker and reduce their speed or briefly to relax pressure on the control yoke, which also would have helped free up the trim wheel. Instead, against all advice, they turned the software back on, which promptly put the plane into an unrecoverable dive. How much the Ethiopian crash even belongs in the same category as the Indonesia crash is debatable when all the facts are considered, albeit depending on whether you are more interested in focusing on aircraft design or on crew training.

To pilots who came up with lots of hand-flying through the military or even the way hobbyist pilots do, it seems possible that understanding the impact of excessive aerodynamic forces on the trim wheel would have been second nature. Perhaps not so with the tens of thousands of classroom- and simulator-trained pilots who staff today’s fast-growing airlines in the developing world.A misplaced sensitivity has been working overtime to suppress discussion of this issue. The goal is not to excuse Boeing’s appalling original software implementation (https://www.wsj.com/articles/boeing-vs-technological-chaos-11572998029?mod=article_inline) or rush the 737 MAX back into service.

The discussion is unwelcome in aviation circles partly because the corollaries are unwelcome. If airplanes today must be designed so mass-produced, classroom-trained pilots can’t crash them, planes tomorrow will be designed to eliminate the pilot completely. In the meantime, better crew training could always be required, but the benefit might not be worth the cost given today’s already low accident rate thanks to the advance of automation.

All this explains the bitterness that has crept into the debate, with a U.S. pilot union accusing Boeing of “blaming dead pilots for its mistakes” and Ethiopian Airlines threatening never to fly the 737 MAX again.

For its part, the FAA knows it can’t guarantee against another Boeing crash any more than it can guarantee against another Airbus (https://quotes.wsj.com/EADSY) crash like the 2009 Air France (https://quotes.wsj.com/AFLYY) disaster in the South Atlantic or 2013’s Asiana Airlines (https://quotes.wsj.com/KR/XKRX/020560) mishap at San Francisco’s airport. In all three cases, and in almost all crashes nowadays, flyable planes are flown into the ground by pilots either accidentally or intentionally (as with the 2015 Germanwings pilot-suicide crash).

Boeing decided this week to curtail production of the grounded MAX for cash-flow reasons. The company knows the plane will fly again (as it should) partly because the global economy’s demand for air travel can’t be met without the MAX.

Meanwhile, regulators have been throwing requirements at Boeing less related specifically to the MAX and very definitely related to new doubts about pilot readiness to deal with unexpected situations. Afoot in global regulatory circles already was a tendency, now accelerated, to reduce expectations about what pilots must know and do from memory. The goal will increasingly be to give them detailed checklists for every occasion. This will likely include, in any failure related to the automatic trim system, an explicit reminder not to overspeed.Whether or not this has much to do with the MAX anymore, it certainly has to do with the future of flying until robots finally push the pilot out of the cockpit altogether.

Edited to improve paragraph formatting

[Less Hair]

Is this another blame the pilots propaganda run? IIRC FAA and EASA and others have grounded the airplane for a reason or two.

[OldnGrounded]

Pilots, Not the Plane, Keep the Boeing MAX GroundedAfter the tragedies, pilots will be expected to know less and religiously follow checklists more.

Basically, another pilot-blaming opinion piece, this one by a WSJ columnist who knows even less about the relevant issues than the average of others who weighed in before him.

(Difficult to read, too. The forum software often collapses paragraph and other formatting, but, if you check the preview before posting, you can manually insert the appropriate breaks,)

[Grebe]

Because that is how to measure AoA.


Because that would measure acceleration, whether gravity or acceleration of the aircraft, not AoA as required.


You appear to be confusing the instrument (display) inside the fight deck, and the sensor from which the indication is derived. These are usually located outside of the flightdeck for most instruments.


787 does use inertial system for synthetic airspeed, etc

https://www.isasi.org/Documents/library/technical-papers/2011/Introducing-787.pdf

Introducing the 787 - Effect on Major Investigations - And Interesting Tidbits

Tom Dodt Chief Engineer – Air Safety Investigation ISASI September, 2011

see pages 39 thru 42

And possibly on 777-??

And boeing has a detailed document on ' Operational use of Angle of Attack

[glofish]

Perhaps not so with the tens of thousands of classroom- and simulator-trained pilots who staff today’s fast-growing airlines in the developing world.A misplaced sensitivity has been working overtime to suppress discussion of this issue. The goal is not to excuse Boeing’s appalling original software implementation (https://www.wsj.com/articles/boeing-vs-technological-chaos-11572998029?mod=article_inline) or rush the 737 MAX back into service.The discussion is unwelcome in aviation circles partly because the corollaries are unwelcome. If airplanes today must be designed so mass-produced, classroom-trained pilots can’t crash them, planes tomorrow will be designed to eliminate the pilot completely. In the meantime, better crew training could always be required, but the benefit might not be worth the cost given today’s already low accident rate thanks to the advance of automation.

What a sick article!
1. It is not "misplaced sensitivity to discuss today's appalling pilot skills"! It's pure and simple greedy, cynical economics who wants to silence the messengers. Name and shame it or shut up if you don't want to be outed as collaborateur.
2. The preposterous assumption that today's low accident is "given" thanks to the advance of automation is outrageous. Automation has its part in improvement, just as it has in many contributions of accidents. Nothing in safety is given.

[OldnGrounded]

The hits just keep on coming. The full text may be behind the paywall for some readers. If folks get blocked, those of us with access can pull it out.

At Boeing, CEO's Stumbles Deepen a Crisis (https://www.nytimes.com/2019/12/22/business/boeing-dennis-muilenburg-737-max.html)
In a tense, private meeting last week in Washington, the head of the Federal Aviation Administration (https://www.nytimes.com/2019/12/11/business/boeing-faa-737-max.html?searchResultPosition=5) reprimanded Boeing’s chief executive for putting pressure on the agency to move faster in approving the return of the company’s 737 Max jet.
This was the first face-to-face encounter between the F.A.A. chief, Stephen Dickson, and the executive, Dennis A. Muilenburg, and Mr. Dickson told him not to ask for any favors during the discussion. He said Boeing should focus on providing all the documents needed to fully describe the plane’s software changes according to two people briefed on the meeting.

It was a rare dressing-down for the leader of one of the world’s biggest companies, and a sign of the deteriorating relationship between Mr. Muilenburg and the regulator that will determine when Boeing’s most important plane will fly again.

The global grounding of the 737 Max (https://www.nytimes.com/2019/11/27/business/boeing-737-max-return-to-service.html?searchResultPosition=4) has entered its 10th month, after two crashes that killed 346 people (https://www.nytimes.com/2019/10/02/business/boeing-737-max-crashes.html), and the most significant crisis in Boeing’s history has no end in sight. Mr. Muilenburg is under immense pressure to achieve two distinct goals. He wants to return the Max to service as soon as possible, relieving the pressure on Boeing, airlines and suppliers. Yet the company and regulators must fix an automated system known as MCAS found to have played a role in both crashes, ensuring the Max is certified safely and transparently. Caught in the middle, Mr. Muilenburg has found himself promising more than he can deliver.

More (https://www.nytimes.com/2019/12/22/business/boeing-dennis-muilenburg-737-max.html)

[Takwis]

Sounds like a trailer for a made-for-TV movie!

I am paywalled, but no real need to read more....

[OldnGrounded]

Sounds like a trailer for a made-for-TV movie!

I am paywalled, but no real need to read more....

Well, here's a bit more, from near the end of the article:

The challenges facing Mr. Muilenburg extend beyond returning the Max to service and the botched space capsule launch on Friday. The F.A.A. is aware of more potentially damaging messages from Boeing employees that the company has not turned over to the agency.

[Takwis]

Thank You, that was worth reading. I'd sure like to hear what some employees are saying.

[slacktide]

The hits just keep on coming. The full text may be behind the paywall for some readers. If folks get blocked, those of us with access can pull it out.

There's nothing new in this article. The Dickson-Muilenberg meeting happened on 12 December, and it was extensively discussed in the media at that time. Must be a slow news day at the Times.

https://www.chicagobusiness.com/manufacturing/faa-scolds-boeing-ceo

[OldnGrounded]

There's nothing new in this article. The Dickson-Muilenberg meeting happened on 12 December, and it was extensively discussed in the media at that time. Must be a slow news day at the Times.

https://www.chicagobusiness.com/manufacturing/faa-scolds-boeing-ceo

I don't think you understand, slacktide.

Yes, most of us read the earlier coverage and are aware of many of the details related in the Times story. It is not true, however, that "[t]here's nothing new" in the Times coverage and, more importantly, it's a long-form summary and analysis in the Sunday edition of the widely-acknowledged US "newspaper of record." Coverage like this has real impacts on the public and the markets.

[BDAttitude]

It's a good wrap up, but there are also some new puzzle pieces in there - at least new to me:
“If it was my call to make, Muilenburg would’ve been fired long ago,” Rep. Peter DeFazio, Democrat of Oregon and the chairman of the House Transportation Committee investigating Boeing, said in an email. “Boeing could send a strong signal that it is truly serious about safety by holding its top decision-maker accountable.”
With delays mounting, Mr. Muilenburg missed a chance to smooth things over with key customers. In September, he attended a gathering of a club of aviation executives called Conquistadores del Cielo at a ranch in Wyoming, according to two people familiar with the trip. As the group bonded while throwing knives and drinking beers, Mr. Muilenburg took long bike rides by himself. It was typical behavior for Mr. Muilenburg, an introverted engineer who prefers Diet Mountain Dew to alcohol, but it left other executives baffled.
Nice anecdote without further insight.

Re Forkner messages:
Mr. Muilenburg said Boeing hadn’t told the F.A.A. about the messages out of concern that doing so would interfere with a criminal investigation being conducted by the Justice Department, according to two people briefed on the call.Mr. Dickson said the lack of transparency would only increase the regulator’s scrutiny of the company.
Mr. Muilenburg continued to press the F.A.A. In early November, he called Mr. Dickson to ask whether he would consider allowing the company to begin delivering airplanes before they were cleared to fly. The administrator said he would look into it but made no commitments, according to an F.A.A. spokesman.In an apparent misunderstanding, Mr. Muilenburg took the call as a green light. The next Monday, the company put out a statement saying it could have the plane to customers by the end of the year.Mr. Dickson told colleagues that he had not agreed to that timeline and felt as though he was being manipulated, according to a person familiar with the matter.
That must have been in the time frame when FAA revoked the authority to issue the Certificate of airworthyness on their behalf.

Preceeding M's walk to Cannossa:
In calls with F.A.A. officials, Boeing engineers began to float an idea for speeding the process: Perhaps the company should ask the agency to break with its foreign counterparts and approve the Max alone?The suggestion alarmed some F.A.A. officials, who worried that approving the Max without agreement from other regulators would be untenable, according to two people familiar with the matter. When they called Mr. Dickson to tell him of Boeing’s plans, he balked at the suggestion and eventually the company backed down.
It seems it's not only some us who are pxxxed
​​​​

[Drc40]

I think he biggest piece of new information in the article is about more messages between Boeing staff about faults with the plane. That’s very new.

I think the FAA should come out with a public statement of immunity and job security for any Boeing employee who was aware and/or participated in company communications regarding concerns about the MAX no matter how insignificant. There might have to be cooperation with law enforcement but that would help flush out the real story of who knew what and when they knew it.

PLEASE QUIT THE PILOT BLAMING. I’m still seeing posts that are clearly veiled with insinuations. I’m also glad nobody took the bait on that post a few pages back claiming not to be a B vs A post.

BTW..I’m not clear if my Canadian brother was actually talking about the MAX in his test flight post. If he was there was no mention of his findings. He might have been testing another plane.

Carry on... :)

[Grebe]

I think he biggest piece of new information in the article is about more messages between Boeing staff about faults with the plane. That’s very new.

I think the FAA should come out with a public statement of immunity and job security for any Boeing employee who was aware and/or participated in company communications regarding concerns about the MAX no matter how insignificant. There might have to be cooperation with law enforcement but that would help flush out the real story of who knew what and when they knew it.

PLEASE QUIT THE PILOT BLAMING. I’m still seeing posts that are clearly veiled with insinuations. I’m also glad nobody took the bait on that post a few pages back claiming not to be a B vs A post.

BTW..I’m not clear if my Canadian brother was actually talking about the MAX in his test flight post. If he was there was no mention of his findings. He might have been testing another plane.

Carry on... :)


RE the continuing bit about pilot training and expertise- such training and even mention in the manuals for the last several decades re trim wheel and use has been deleted- and sims apparantly did NOT duplicate the real forces involved

https://theaircurrent.com/aviation-safety/vestigal-design-issue-clouds-737-max-crash-investigations/

for specifics.

And in this SLF defense of the pilots and the continuing bit re reduce speed and fly and yada yada yada - Consider if you were less than 5k above ground, cows getting bigger no matter what, and knowing that pulling power give you more NOSE DOWN when you already have the secret HAL overriding you every 5 seconds when trim switch is released, and pulling back on yoke expecting the NG response which stops the Stab trim- NOT knowing that that doesn't work either, and never mentioned in any AD--- what other result would one expect?? :mad:

[SteinarN]

Some more, actually the complete nytimes piece, sorry for the formatting;

"The global grounding of the 737 Max (https://www.nytimes.com/2019/11/27/business/boeing-737-max-return-to-service.html?searchResultPosition=4) has entered its 10th month, after two crashes that killed 346 people (https://www.nytimes.com/2019/10/02/business/boeing-737-max-crashes.html), and the most significant crisis in Boeing’s history has no end in sight. Mr. Muilenburg is under immense pressure to achieve two distinct goals. He wants to return the Max to service as soon as possible, relieving the pressure on Boeing, airlines and suppliers. Yet the company and regulators must fix an automated system known as MCAS found to have played a role in both crashes, ensuring the Max is certified safely and transparently. Caught in the middle, Mr. Muilenburg has found himself promising more than he can deliver."

"After the crashes, but before the plane was grounded, Mr. Muilenburg called President Trump (https://www.nytimes.com/2019/03/12/business/boeing-flights-grounded.html?searchResultPosition=9) and expressed confidence in the safety of the Max. He has repeatedly made overly optimistic projections about how quickly the plane would return to service, pushing for speedy approval from regulators. The constantly shifting timeline has created chaos for airlines, which have had to cancel thousands of flights and sacrifice billions of dollars in sales.In his few public appearances, Mr. Muilenburg’s attempts to offer a sincere apology for the accidents have been clumsy, prolonging Boeing’s reputational pain. His performance has left lawmakers irate. The families of crash victims, convinced the company does not care about their loss, have repeatedly confronted him with posters of the dead."

"The missteps led Boeing to one of the most consequential decisions in its 103-year history, when it announced on Monday that it was temporarily shutting down (https://www.nytimes.com/2019/12/16/business/boeing-737-max.html) the 737 factory, a move that has already begun rippling through the national economy.The Max is Boeing’s best seller, with tens of billions of dollars in future sales at stake. Boeing stock has fallen by 22 percent in this crisis, costing the company more than $8 billion and spreading pain throughout a supply chain that extends to 8,000 companies (https://www.nytimes.com/2019/12/18/business/boeing-737-max-suppliers.html?searchResultPosition=5). On Friday, Spirit AeroSystems, which makes the Max fuselage, said it would stop production of the part (https://www.reuters.com/article/us-boeing-737-max-spirit-aerosystm/boeing-supplier-spirit-aerosystems-to-suspend-production-of-737-max-parts-idUSKBN1YO1GB) next month."“Throughout this process our No. 1 priority has been safety,” Gordon Johndroe, a Boeing spokesman, said in a statement. “We have learned a lot this year and our company is changing.”

Last week, when Mr. Trump called (https://www.nytimes.com/2019/12/18/business/trump-boeing-dennis-muilenburg.html?searchResultPosition=1) Mr. Muilenburg to discuss Boeing’s problems, the chief executive assured the president that a production shutdown would only be temporary. But Boeing still faces serious hurdles. The company has not delivered a complete software package to the F.A.A. for approval. In recent simulator tests, pilots did not use the correct emergency procedures, raising new questions about whether regulators will require more extensive training for pilots to fly the plane or whether the procedures needed to be changed, according to two people briefed on the matter."



"And on Friday, a new space capsule Boeing designed for NASA failed to reach (https://www.nytimes.com/2019/12/20/science/boeing-starliner-launch.html) the correct orbit, another blow to company morale and a setback for the United States space program."“If it was my call to make, Muilenburg would’ve been fired long ago,” Rep. Peter DeFazio, Democrat of Oregon and the chairman of the House Transportation Committee investigating Boeing, said in an email.

“Boeing could send a strong signal that it is truly serious about safety by holding its top decision-maker accountable. ”From the earliest days of the grounding in March, shortly after the crash of Ethiopian Airlines Flight 302 and months after the first Max crash (https://www.nytimes.com/2019/10/25/world/asia/lion-air-crash-report.html), off Indonesia, Mr. Muilenburg tried to put the episode behind him as swiftly as possible, telling airlines it would last just weeks."


“By the time April rolled around, Boeing was telling us next week, next month,” Gary Kelly, the chief executive of Southwest Airlines, said in an interview. “We were a week away, weeks away, three weeks away.”That misplaced optimism made it impossible for airlines including Southwest, which is Boeing’s biggest 737 customer, to reliably plan their routes. “It was really creating havoc,” Mr. Kelly said.

In August, regulators from Europe, Canada and Brazil flew to Seattle and joined F.A.A. officials for a meeting with Boeing. They were expecting to review reams of documentation describing the software update for the Max. Instead, the Boeing representatives offered a brief PowerPoint presentation, in line with what they had done in the past. The regulators left the meeting early.“We were looking for a lot more rigor in the presentation of the materials,” said Earl Lawrence, the head of the F.A.A.’s aircraft certification office. “They were not ready.”

"With delays mounting, Mr. Muilenburg missed a chance to smooth things over with key customers. In September, he attended a gathering of a club of aviation executives called Conquistadores del Cielo at a ranch in Wyoming, according to two people familiar with the trip. As the group bonded while throwing knives and drinking beers, Mr. Muilenburg took long bike rides by himself. It was typical behavior for Mr. Muilenburg, an introverted engineer who prefers Diet Mountain Dew to alcohol, but it left other executives baffled.

October brought a string of bad news for Mr. Muilenburg. The board stripped him of his title as chairman, a stinging rebuke (https://www.nytimes.com/2019/10/13/business/boeing-board-dennis-muilenburg.html) of his leadership. The decision, the board said, would allow him to focus on the single most important job at the company: bringing the Max back to service.""About two weeks before Mr. Muilenburg testified in front of Congress for the first time, the company disclosed to lawmakers (https://www.nytimes.com/2019/10/18/business/boeing-flight-simulator-text-message.html) instant messages from 2016 in which a Boeing pilot complained that the system known as MCAS, which was new to the plane, was acting unpredictably in a flight simulator. Boeing discovered the instant messages in January, but Mr. Muilenburg did not read them at the time, instead telling the company’s legal team to handle them. The messages included the pilot saying he “basically lied to the regulators (unknowingly).” When Mr. Dickson learned of the messages in October, he sent a one-paragraph letter to Mr. Muilenburg demanding an explanation for “Boeing’s delay in disclosing the document to its safety regulator.”

Mr. Muilenburg and Mr. Dickson, who took over the F.A.A. (https://www.nytimes.com/2019/07/24/us/politics/federal-aviation-administration-stephen-dickson.html?searchResultPosition=6) this summer, spoke for the first time later that day. Mr. Muilenburg said Boeing hadn’t told the F.A.A. about the messages out of concern that doing so would interfere with a criminal investigation being conducted by the Justice Department, according to two people briefed on the call.Mr. Dickson said the lack of transparency would only increase the regulator’s scrutiny of the company."

"Still, Mr. Muilenburg continued to project confidence, telling investors on an earnings call in October that he expected regulators to begin approving the Max by the end of the year. The company had just fired Kevin McAllister (https://www.nytimes.com/2019/10/22/business/boeing-kevin-mcallister.html), the chief executive of Boeing’s commercial division who had been overseeing work on the Max. Despite Mr. Muilenburg’s assurances, airline discontent was growing. The next day, American Airlines joined a chorus of Boeing customers complaining about the growing costs of the Max crisis. Doug Parker, American’s chief executive, said on a call with investors that he was working to “ensure that American is compensated for the lost revenue that the Max grounding has caused, the missed deadlines and extended grounding.”
“We’re working to ensure that Boeing shareholders bear the cost of Boeing’s failures,” Mr. Parker added. “Not American Airlines’ shareholders.”

In two days of congressional hearings at the end of October, Mr. Muilenburg faced withering criticism (https://www.nytimes.com/2019/10/30/business/boeing-muilenburg-testimony-congress.html) from lawmakers, who told him to resign or take a pay cut. Mr. Muilenburg said it was up to the board to make decisions about his multimillion-dollar compensation. He invoked his upbringing on an Iowa farm so many times that he elicited jeers from family members of crash victims who were present. In an interview on CNBC after the hearings, the chairman of Boeing’s board, David Calhoun, said the board was confident in its chief executive. “From the vantage point of our board, Dennis has done everything right,” Mr. Calhoun said. “If we successfully get from where he started to where we need to end up, I would view that as a very significant milestone and something that speaks to his leadership and his courage and his ability to execute and get us through this.

”Mr. Muilenburg continued to press the F.A.A. In early November, he called Mr. Dickson to ask whether he would consider allowing the company to begin delivering airplanes before they were cleared to fly. The administrator said he would look into it but made no commitments, according to an F.A.A. spokesman. In an apparent misunderstanding, Mr. Muilenburg took the call as a green light. The next Monday, the company put out a statement saying it could have the plane to customers by the end of the year. Mr. Dickson told colleagues that he had not agreed to that timeline and felt as though he was being manipulated, according to a person familiar with the matter. That week, he put out a memo (https://www.nytimes.com/2019/11/15/business/boeing-faa-737-max.html) and a video urging employees to resist pressure to move quickly on the Max approval."

"This month, anxiety levels rose at Boeing’s factory in Renton, Wash. Several key tests had not yet been completed, and European regulators would soon leave work for the holidays and not return until the beginning of January. In calls with F.A.A. officials, Boeing engineers began to float an idea for speeding the process: Perhaps the company should ask the agency to break with its foreign counterparts and approve the Max alone? The suggestion alarmed some F.A.A. officials, who worried that approving the Max without agreement from other regulators would be untenable, according to two people familiar with the matter. When they called Mr. Dickson to tell him of Boeing’s plans, he balked at the suggestion and eventually the company backed down.A week later, Mr. Dickson brought Mr. Muilenburg into the agency’s Washington headquarters for their first in-person meeting.

There, Mr. Dickson said he had done the math, and there was no way the Max could fly by the end of the year. When Mr. Muilenburg brought up the logistics of delivering Max jets to customers, Mr. Dickson would not discuss the issue, two people familiar with the matter said. Boeing’s representatives said they might need to consider temporarily shutting down production. Mr. Dickson told them to do what they needed to do, saying the agency was focused on conducting a thorough review. Four days later, Boeing announced it would bring the 737 factory to a halt. There was no discussion of removing Mr. Muilenburg as chief executive at last week’s board meeting in Chicago where the shutdown was debated, according to three people briefed on the meeting.

The challenges facing Mr. Muilenburg extend beyond returning the Max to service and the botched space capsule launch on Friday. The F.A.A. is aware of more potentially damaging messages from Boeing employees that the company has not turned over to the agency. Other important planes are behind schedule. New defects have been found on older models of the 737. Boeing lost two major pieces of business to Airbus, its European rival, this month. “This hasn’t been their best and finest hour,” said Mr. Kelly, the Southwest Airlines chief executive. “There’s mistakes made and they need to address those.

”With the first anniversary of the Ethiopian accident approaching in March, Boeing recently asked a representative for the families of crash victims if it would be appropriate for Mr. Muilenburg to attend the memorial. They said no. “He is not welcome there,” said Zipporah Kuria, whose father, Joseph Waithaka, was killed in the second crash. “Whenever his name is said, people’s eyes are flooded with tears.”

[GemDeveloper]

The NYT piece, for which thanks, SteinarN, includes:

”Mr. Muilenburg continued to press the F.A.A. In early November, he called Mr. Dickson to ask whether he would consider allowing the company to begin delivering airplanes before they were cleared to fly. The administrator said he would look into it but made no commitments, according to an F.A.A. spokesman. In an apparent misunderstanding, Mr. Muilenburg took the call as a green light. The next Monday, the company put out a statement saying it could have the plane to customers by the end of the year. Mr. Dickson told colleagues that he had not agreed to that timeline and felt as though he was being manipulated, according to a person familiar with the matter. That week, he put out a memo (https://www.nytimes.com/2019/11/15/business/boeing-faa-737-max.html) and a video urging employees to resist pressure to move quickly on the Max approval."

This all sounds remarkably similar to the 787 wing conducting strips issue. I paraphrase but it was something like: "These strips cost us time and money to include on the build, is it all right if we leave them out?" "We'll have a think about it". Well, whilst the FAA still was having a think about it, Boeing built 40 aircraft without the strips.

I'm still unclear where this landed. Did the FAA actually say it was all right... or not? And if not, where are those 40 aircraft now? Are they more prone to lightning damage and, heaven forbid, fire? Who's operating them? Do they know about the potentially increased risk? Do their insurers know?

Arrogance or ineptitude?

[JPJP]

It’s been reported that Boeing is fighting back against ‘the unfair media reporting’ that is sullying their reputation. They don’t seem to understand that merely presenting the facts, is enough.

Attached below is The Wall Street Journals editorial. Written by a business reporter with zero apparent background in aviation or flying. He’s obviously being fed a pilot blaming narrative, and seems to be leading Boeing’s newest PR defence. His conclusions are certainly bizarre - two crashes where a lack of information was a factor. Lead to less education ?

As Manuel would say - ‘Que ?’

Ghosts and goblins are keeping the troubled newBoeing (https://quotes.wsj.com/BA) 737 MAX out of the air now. So much so that the company this week announced it will stop an assembly line that was producing dozens of planes a month to be stored in parking lots.

After the first MAX crash took place in Indonesia in late 2018, the U.S. Federal Aviation Administration decided to keep the plane flying. Consternation followed a Journal report (https://www.wsj.com/articles/internal-faa-review-saw-high-risk-of-737-max-crashes-11576069202?mod=article_inline) last week showing that at the time the agency anticipated a MAX crash rate three times that of comparable airplanes. In the FAA’s defense, it also presumed that Boeing would fix the MAX’s faulty flight-control software well before another crash occurred. In the meantime, impressed upon pilots would be that any glitch could be quickly neutralized by throwing a couple of prominent switches.

Which makes all the more urgent understanding why the next crash, involving Ethiopian Airlines Flight 302, happened just months later. For the last three minutes of what was a six-minute flight, the offending software system, as per Boeing’s instructions after the Indonesia crash, was disabled. Yet the pilots never cut takeoff thrust despite a loud clacker warning that their airspeed was exceeding the plane’s design limit. With so much force acting on the plane’s control surfaces, they were unable, as Boeing’s new checklist also specified, to move the trim wheel manually to correct the nose-down trim imposed by the faulty software.

They didn’t use the three minutes to heed the clacker and reduce their speed or briefly to relax pressure on the control yoke, which also would have helped free up the trim wheel. Instead, against all advice, they turned the software back on, which promptly put the plane into an unrecoverable dive. How much the Ethiopian crash even belongs in the same category as the Indonesia crash is debatable when all the facts are considered, albeit depending on whether you are more interested in focusing on aircraft design or on crew training.

To pilots who came up with lots of hand-flying through the military or even the way hobbyist pilots do, it seems possible that understanding the impact of excessive aerodynamic forces on the trim wheel would have been second nature. Perhaps not so with the tens of thousands of classroom- and simulator-trained pilots who staff today’s fast-growing airlines in the developing world.

A misplaced sensitivity has been working overtime to suppress discussion of this issue. The goal is not to excuse Boeing’s appalling original software implementation (https://www.wsj.com/articles/boeing-vs-technological-chaos-11572998029?mod=article_inline) or rush the 737 MAX back into service.

The discussion is unwelcome in aviation circles partly because the corollaries are unwelcome. If airplanes today must be designed so mass-produced, classroom-trained pilots can’t crash them, planes tomorrow will be designed to eliminate the pilot completely. In the meantime, better crew training could always be required, but the benefit might not be worth the cost given today’s already low accident rate thanks to the advance of automation.

All this explains the bitterness that has crept into the debate, with a U.S. pilot union accusing Boeing of “blaming dead pilots for its mistakes” and Ethiopian Airlines threatening never to fly the 737 MAX again.

For its part, the FAA knows it can’t guarantee against another Boeing crash any more than it can guarantee against another Airbus (https://quotes.wsj.com/EADSY) crash like the 2009 Air France (https://quotes.wsj.com/AFLYY) disaster in the South Atlantic or 2013’s Asiana Airlines (https://quotes.wsj.com/KR/XKRX/020560) mishap at San Francisco’s airport. In all three cases, and in almost all crashes nowadays, flyable planes are flown into the ground by pilots either accidentally or intentionally (as with the 2015 Germanwings pilot-suicide crash).

Boeing decided this week to curtail production of the grounded MAX for cash-flow reasons. The company knows the plane will fly again (as it should) partly because the global economy’s demand for air travel can’t be met without the MAX.

Meanwhile, regulators have been throwing requirements at Boeing less related specifically to the MAX and very definitely related to new doubts about pilot readiness to deal with unexpected situations. Afoot in global regulatory circles already was a tendency, now accelerated, to reduce expectations about what pilots must know and do from memory. The goal will increasingly be to give them detailed checklists for every occasion. This will likely include, in any failure related to the automatic trim system, an explicit reminder not to overspeed.

Whether or not this has much to do with the MAX anymore, it certainly has to do with the future of flying until robots finally push the pilot out of the cockpit altogether. - Holman W Jenkins Jr.



https://www.wsj.com/news/author/5469

[Marly Lite]

Can a Boeing driver educate me about the low altitude level off auto-throttle issue? I have just seen a yootoobe video describing in a little detail that this is a problem on many Boeings, and may have been a contributary factor in the Air Ethiopia crash as the rapid acceleration caused by a continued high N1 at level off would lead to a wildly out of trim situation.

The main point of the video was that IF this was a factor, then the problem is MUCH MUCH bigger for boeing than just MCAS.

Thoughts?

Cheers, Marly.

[gums]

Salute!

Gotta add once again the fact that if the Lion crew(s) knew about MCAS and then the AD that came out which did not specifically address MCAS and how it worked and did not simply state that if the trim system seemed weird, then turn the thing off and revert to the stoopid little wheel before getting too fast and oh yeah, the wheel trim switch works until you turn off those doofers on the center pedestal, and the old cut-out switch on the yoke doesn't work like it did on the thousands of 737 planes before, and... and...

BEAM ME UP!

And some dweeb blames the pilots for not being Chuck Yeager clones and reacting to a new characteristic of the plane within a few seconds?
I will bet that 99 outta 100 of 737 drivers across the globe would have handled both accidents if they knew about MCAS and how it worked and had a procedure that simply stated to turn off the trim after using the basic system to trim nose up. Leave the test pilot crapola to test pilots, and write up the entire sequence of events ( unlike the Lion crew that assumed the STS was working backwards).

Gums sends...

P.S. Show us the plots of the pitch moments versus AoA without MCAS. Hmmmmm.....

[OldnGrounded]

P.S. Show us the plots of the pitch moments versus AoA without MCAS. Hmmmmm.....

Indeed. Inquiring minds want to know.

[568]

Can a Boeing driver educate me about the low altitude level off auto-throttle issue? I have just seen a yootoobe video describing in a little detail that this is a problem on many Boeings, and may have been a contributary factor in the Air Ethiopia crash as the rapid acceleration caused by a continued high N1 at level off would lead to a wildly out of trim situation.

The main point of the video was that IF this was a factor, then the problem is MUCH MUCH bigger for boeing than just MCAS.

Thoughts?

Cheers, Marly.After take off, if the AFDS has "captured the lower MCP attitude" you may still be in "take off thrust" so the aircraft will not transition to "climb thrust". Selecting a pitch mode (VNAV/FLCH as Boeing recommends FLCH) will bring the aircraft into "climb thrust". Unless the crew check's the A/T and pitch FMA's to ensure climb thrust is set, then the aircraft starts to increase speed to approximately 240 knots below 10,000 feet. VNAV will honor flap placard speeds minus 5 knots.

[Loose rivets]

“If it was my call to make, Muilenburg would’ve been fired long ago,” Rep. Peter DeFazio, Democrat of Oregon and the chairman of the House Transportation Committee investigating Boeing, said in an email. “Boeing could send a strong signal that it is truly serious about safety by holding its top decision-maker accountable.”

Sounds like deterrent sentencing, a subject that makes my blood boil. From that baying, I get the feeling DeFazio is a direct descendant of witch burners.


Mr. Muilenburg continued to press the F.A.A. In early November, he called Mr. Dickson to ask whether he would consider allowing the company to begin delivering airplanes before they were cleared to fly. The administrator said he would look into it but made no commitments, according to an F.A.A. spokesman.

Huh, my suggestion a few days ago wasn't so off-the-wall after all.

Back on the technical/operating aspects. How do pilots on this forum react to being 'ordered' to not turn the stabilizer power cut-off toggles back on? I've always been pretty certain that I would have powered up the system for another try of the electric trim as soon as I found I physically could not turn the trim wheels. Again the concept of reaching for a checklist in the midst of that chaos is anathema to me, but having said that, even the ET captain probably only had the sketchiest idea about the system, even post the advisory. I can't imagine being so hazy about the most powerful aerodynamic surface on the aircraft, even given that I wouldn't have known about MCAS.

I recall clearly how deeply we were questioned on the ARB type ratings. I also remember the first pilots and engineers coming back from the DC10 course. They had been worried about their ability to learn the systems, but utterly relieved to find that so much was simply check-list derived. An indication of what was to come.

[Grebe]

Good description of just how badly Boeing fouled up- which continues to this day ...:ugh:

By Andrew Tangel,
Alison Sider and
Andy Pasztor
Dec. 22, 2019 7:52 pm ET

After the grounding of Boeing Co. BA -1.65% ’s 737 MAX jet dragged on through the summer, Dennis Muilenburg, the Boeing CEO, decided to seek some advice.

In 2017, Oscar Munoz, the chief of United Airlines Holdings Inc., had faced his own public backlash after police dragged a bloodied passenger off a flight. Boeing was under fire from industry officials and victims’ families who thought its response to two crashes of its newest plane was similarly tone-deaf.

Show more warmth, Mr. Munoz told the 55-year-old CEO during a visit in the airline chief’s office inside Chicago’s Willis Tower, according to United officials. After all, Mr. Munoz told him, 346 people perished on Boeing’s planes.

Since the dual crashes, Boeing has fumbled its response, treating the disasters more like typical accidents, repeatedly minimizing its own technical and design mistakes and underestimating the backlash from regulators, customers and the flying public.

At the center is Mr. Muilenburg who appeared to rely too heavily on data and legal advice to make decisions as he sought to find what went wrong, communicate and get Boeing’s plane flying again. His choices failed to resolve—and sometimes exacerbated—friction with regulators and airlines, indicating that until recently he may not have fully grasped the severity of the challenges confronting him.

Turbulent Tenure
Boeing shares surged during CEO Dennis Muilenburg's tenure, with its market value peaking above $250 billion just days before the second crash of a 737 MAX.


He has prioritized getting the MAX back aloft while struggling with the complexities of politics and public relations, technical hurdles and restoring passenger confidence. He finally conceded mistakes after declining to acknowledge flaws in a flight-control system implicated in both accidents.

With the grounding set to last at least a year, Mr. Muilenburg and his supporters now say his approach is evolving. He went from ardently defending Boeing to belatedly acknowledging mistakes, seeking input from customers, apologizing and meeting with grieving families. He has begun talking publicly about Boeing’s newfound humility. “We’ve been humbled by these two accidents,” Mr. Muilenburg said in an interview last week. “We’re making changes to our company, and I’m changing as a leader as well.”

Mr. Muilenburg is still left with a deepening crisis. His repeated assurances of the plane’s safety have failed to win regulators’ approval. A string of Boeing’s optimistic predictions for when regulators would certify the aircraft for flying haven’t panned out and have indeed antagonized air-safety regulators world-wide.


Boeing, the largest U.S. manufacturing exporter, is suspending MAX production starting January. The production suspension, which prompted President Trump to call Mr. Muilenburg, has big implications for Boeing’s vast network of suppliers and their employees—and the American economy. U.S. industry officials don’t expect the Federal Aviation Administration to lift its flight ban until at least February.

Making matters worse, Boeing this month botched a space capsule’s long-awaited test flight—it went into the wrong orbit—raising fresh questions about management’s ability to pull off big feats.

Boeing’s string of missteps is fueling speculation among airline, government and other industry officials about how long Mr. Muilenburg can keep his job. Boeing’s board stripped him of his dual role as chairman earlier this year.

After the failed space mission, Boeing’s new chairman, Dave Calhoun, on Friday stood by earlier televised comments backing Mr. Muilenburg. A Boeing spokesman said Sunday Mr. Calhoun stands by his endorsement.

Mr. Muilenburg, an engineer by training, came to lead Boeing after a long stint in the aerospace giant’s defense business that deals with governments rather than consumer-facing airlines.

People who have worked with him describe him as a linear thinker better suited at delivering bullet points than connecting with people.

The first 737 MAX crashed in Indonesia in October 2018. In March, Mr. Muilenburg was at his Chicago-area home when a Boeing operations center called overnight to alert him of the second crash, in Ethiopia, said a senior Boeing official.

Mr. Muilenburg and his team discussed whether to let the MAX keep flying or recommend grounding it, said people familiar with the discussions.

A flood of concern was cresting world-wide, and some in the FAA urged a more drastic response. Mr. Muilenburg and senior FAA officials opted to wait. Despite early reports showing possible similarities in some aspects of the two crashes, other data suggested sharp differences. That information proved wrong.


Boeing sought to allay concerns by saying the FAA planned to approve a “software enhancement” to a flight-control system known as MCAS no later than April that would make “already safe aircraft even safer.” Mr. Muilenburg expressed confidence in the MAX’s safety during a phone call with Mr. Trump, said a person familiar with the conversation.

“It’s important that we take action based on data and information,” Mr. Muilenburg said in the interview, of those discussions, defending his decision not to call for grounding immediately. Emergence of new data showing similarities with the first MAX crash “ultimately led to the right decision, and one that we fully supported.”

New satellite data suggesting a possible MCAS misfire similar to the first accident cinched the argument. The FAA become the last of the regulators to ban flights.

Mr. Muilenburg said little publicly in the following weeks. In late April, he assured Wall Street analysts there was “no technical slip” in the system’s certification, speaking narrowly about how Boeing won initial FAA approval. “It was done the right way,” Mr. Muilenburg said in the interview.

“It was done to the process.”
United CEO Oscar Munoz told the Boeing CEO to show more warmth. Photo: Anna Moneymaker/Bloomberg News

But he acknowledged no Boeing flaws at the time. He later noted, at a press conference that month, that pilots in the accidents didn’t follow all emergency procedures

He began to learn more about the MAX’s design problems as he made more frequent trips to the Seattle area, where the company manufactures the plane. He discovered Boeing engineers had based their MCAS designs with a fatal flaw and a longstanding assumption that pilots would respond to a malfunction as they would to a similar cockpit emergency. They didn’t take into account how confusing such an emergency could prove, making it difficult for pilots to respond quickly.

“That’s where we made the mistake,” Mr. Muilenburg said in the interview. “These design assumptions are no longer correct.”

Mr. Muilenburg also learned of a related error, one his Seattle colleagues had known since 2017: Certain cockpit alerts on the MAX weren’t working as intended—or expected by the FAA and airlines—on all of the aircraft.

Due to a software error, they were activated only as part of an optional package. After the 2018 crash, Boeing told the FAA and Southwest Airlines Co. , its largest MAX buyer, about the mistake, but Mr. Muilenburg didn’t learn about the mixup until after the March crash, according to the senior Boeing official and people briefed on the timeline.

Boeing released public statements correcting the record and Mr. Muilenburg later conceded communications lapses. He later launched a restructuring of the company’s Seattle-based engineering and safety departments to give him more direct oversight.


Growing impatience

By June, the MAX crisis cast a pall over the Paris Air Show, where Boeing traditionally showcases airliner deals. This time, scores of its best-selling plane were piling up in storage and Boeing officials instead touted how they were adding safeguards to the MAX.

Mr. Muilenburg made few public appearances but had a private meeting with his counterpart at the FAA, acting administrator Dan Elwell, people familiar with the meeting said. The two met inside the back of a parked military plane, not at Boeing’s base at the show, these people said.

Mr. Elwell asked Muilenburg that Boeing slow down its talk of progress, giving the FAA space to exercise scrutiny, these people said. The agency needed to be seen as independent.

FAA officials had grown impatient with Boeing’s optimism about putting the MAX back in service. The regulator was taking a reputation hit after delegating its authority to Boeing for years, and the crisis was fueling questions on Capitol Hill about its coziness with the company. The FAA was working with foreign regulators to lift their MAX grounding together.

“You’re right,” Mr. Muilenburg said, according to the people familiar with the meeting. “We’re not going to push.”

Yet Boeing continued to provide public estimates of the MAX’s return to flight, further irritating the FAA.

Mr. Muilenburg said in the interview Boeing considered it necessary to telegraph such information to suppliers. “We haven’t always been accurate on that,” Mr. Muilenburg said. “But ultimately no matter what I say, in terms of the baseline calendar, the regulators will determine the timeline.”


As months ticked by, Mr. Muilenburg hadn’t had contact with families of victims from either crash. Bob Clifford, a Chicago lawyer suing the plane maker in the Ethiopian case, suggested to Boeing officials that they meet with relatives to discuss how to spend $50 million it planned to donate—to no avail, Mr. Clifford said.

Mr. Muilenburg said he had wanted to meet them earlier but didn’t want to make them uncomfortable. “I tried to put myself in their position,” he said in the interview. “What would it be like? I’d want to have some time to grieve.”

By fall, Boeing faced a new problem: European regulators wanted their own check of the FAA’s MAX safety approvals, which would inevitably lead to more delays.

Boeing executives were bracing for U.S. lawmakers to call Mr. Muilenburg to testify and ask about whom he had held accountable, said a person familiar with their thinking. No one at Boeing had been singled out.


Boeing officials had also been debating what to do with potentially damning information found during the company’s document-gathering for the Justice Department’s criminal investigation into whether Boeing misled the FAA or airlines, said a person familiar with the discussions.

In instant messages between two Boeing pilots in late 2016, Mark Forkner, who was in charge of winning FAA approval for aircraft manuals and training, suggested he “basically lied to the regulators (unknowingly)” after encountering problems with the MCAS system in a simulator.

Mr. Forkner’s lawyer declined to comment Sunday but has said his client was referring to problems with the simulator, not the MAX.

Boeing passed the messages to prosecutors in February but decided against telling its own regulator, people familiar with the matter said.
Disclosing them to the FAA wouldn’t be appropriate, because the agency was subject to the same probe, Boeing lawyers reasoned, and Mr. Forkner’s government counterpart was a likely witness, one of these people said.

As congressional hearings drew near, Boeing lawyers decided the company had to turn over the documents to the House Transportation Committee, and notified the Department of Transportation, the FAA’s parent agency. The belated disclosure inflamed Boeing’s relationship with the FAA, angering Steve Dickson, the FAA’s newly installed boss, people close to the agency said.
‘Forcing my hand’

In a call with Mr. Muilenburg after the House panel released the chats, Mr. Dickson told the CEO that Boeing’s withholding the documents would effectively invite stricter regulation, people familiar with the conversation said.

“You’re forcing my hand,” Mr. Dickson told Mr. Muilenburg, according to one of these people.

Mr. Muilenburg later told a Senate committee he relied on his legal counsel to provide it to the appropriate authorities and didn’t recall a specific conversation about which authorities to give it to. He told the committee he later apologized to Mr. Dickson over how Boeing disclosed it to the FAA.

To prepare for his October congressional testimony, Mr. Muilenburg held mock sessions including with Boeing’s general counsel Brett Gerry, who played a committee chairman, said a person familiar with the preparation. Government-affairs chief Tim Keating and spokesman Gordon Johndroe joined the sessions.

They asked Mr. Muilenburg tough questions, including whether he had focused on profit at the expense of safety. Mr. Muilenburg expressed surprised at the tone, another person familiar with the sessions. Questions also addressed Boeing’s mistakes.

Ahead of the hearings, Mr. Muilenburg requested to meet with Bayihe Demissie, who lives in Ethiopia and was in Chicago—his wife was a flight attendant on the Ethiopian flight. It was the CEO’s first meeting with a victim’s relative.

Mr. Demissie said he told Mr. Muilenburg he didn’t know how to be a single father to his young son. “I never pictured this life,” he recalled telling the CEO. He questioned why Mr. Muilenburg had taken so long to reach out. The CEO told him “We cannot let your wife be forgotten,” said a person familiar with the meeting.

Days later in Washington, D.C., Mr. Muilenburg met with a group of crash victims’ relatives and tried explaining Boeing’s decisions. “Every time you turn around Boeing seems to be shooting themselves in the foot,” said Mr. Clifford. “I think they’re trying to correct that.”

Mr. Muilenburg said meeting the families was a “stark and difficult reminder of the importance” of Boeing’s work. “It’s changed me forever.”

During hearings, Mr. Muilenburg struggled to defend his credibility and, at times, to respond to direct questions. He said he apologized for not turning over Mr. Forkner’s messages to the FAA earlier.

Lawmakers demanded to know about Boeing’s decisions in creating the flight-control system. Some asked why he hadn’t resigned.

U.S. Rep. Dina Titus (D-Nev.), alluding to Mr. Forkner’s emails, asked: “You’re not trying to Jedi mind-trick us here today on this committee?”

“Congresswoman,” he said, “I’m telling you the truth.”
Boeing further upset its relationship with the FAA soon after, saying in November it expected the MAX ban to lift a month later and training approval to come in January.

The FAA’s Mr. Dickson wrote an internal Nov. 14 memo, which the Journal reviewed, saying the FAA wouldn’t work by any schedule and separately signaled the FAA wouldn’t allow the MAX to fly again until 2020.

He called Mr. Muilenburg to a meeting in Washington, D.C., and chided him for the perceived pressure.

Write to Andrew Tangel at l333333, Alison Sider at 333333

END Chopped out images and captions

[Grebe]

Making matters worse, Boeing this month botched a space capsule’s long-awaited test flight—it went into the wrong orbit—raising fresh questions about management’s ability to pull off big feats.


Yep an 11 hour error --- AM vs PM ??

repeat after me ...When mickeys LITTLE hand is at . . .

[edmundronald]

Salute!

And some dweeb blames the pilots for not being Chuck Yeager clones and reacting to a new characteristic of the plane within a few seconds?

Gums sends...

P.S. Show us the plots of the pitch moments versus AoA without MCAS. Hmmmmm.....

Gums,

Why don’t you whisper that question in the ear of your elected congresscritter?

My belief is that it’s not a simple curve, but depends on some additional factors eg. thrust vs. airspeed, and extant stab setting, and has some really nasty hidden non-linearities FOR SOME PARAMETER VALUES.
In fact the pitchdown on nose down might be even more lethal than the pitch up on nose up.

Edmund

[MechEngr]

Knowing what we know about the system at this point, I can envision a situation where I would consider turning the switches back on, quickly correcting the trim, and turning them back off. I was once in a similar situation with an electrical fire. I would much rather not fly an airplane that would put me in that position...especially with 180 or so lives in my hands.

It's known that the ET302 crew did restore the trim cutouts and did try to trim, but only long enough to try to force the autopilot back on under conditions that training should have told them that the autopilot cannot function. And then they left the trim motors enabled and here we are.

You say you would rather not fly a plane like that. Would you do it anyway if you knew you would be fired otherwise? I know at least one pilot who resigned from Ethiopian Airlines after the first crash on the grounds the airline management didn't do enough.

Apparently Ethiopian Airlines is working closely with the investigation and withholding the CVR from the international investigation community, providing only snippets that support a particular narrative. It's the flagship of technology and modernity for Ethiopia and a source of national pride. The stakes are high for Boeing; they are higher for the government of Ethiopia.

[568]

Yep an 11 hour error --- AM vs PM ??

repeat after me ...When mickeys LITTLE hand is at . . .Don't think younger folks know how to read clocks anymore let alone set them properly. The current state of our world today, ho hum!https://www.usatoday.com/story/news/nation-now/2018/05/04/analog-clocks-students-cant-read-schools-still-use/580935002/

[FlightlessParrot]

I'm still unclear where this landed. Did the FAA actually say it was all right... or not?

No, they said they'd consider it. Then Boeing went ahead, knowing that they could say "We discussed this with the FAA, and they didn't tell us not to." I've been the victim of that manoeuvre, on a vastly smaller scale. SOP for dodgy people.

[Water pilot]

The stakes are high for Boeing; they are higher for the government of Ethiopia.I really doubt that, it is just more spin from Boeing's creative marketing division. Unlike Boeing, this incident does not have the possibility (however remote) of forcing Ethiopia into bankruptcy. The issues facing the government of Ethiopia are far more significant than who gets the blame for a jet crash, and if it were in fact the fault of a pilot panicking and doing the wrong thing than that would actually be a fairly simple thing for the government to shrug off, especially in a country were so many have already died in war. Mechanical failure could be either the fault of Boeing or the airline; it would be much harder for them if for example the tail had fallen off and there was a report that the plane had been involved in a ramp incident.Nobody in the United States is worried about losing an election because of the Atlas Air crash.

[fdr]

Salute!

Gotta add once again the fact that if the Lion crew(s) knew about MCAS and then the AD that came out which did not specifically address MCAS and how it worked and did not simply state that if the trim system seemed weird, then turn the thing off and revert to the stoopid little wheel before getting too fast and oh yeah, the wheel trim switch works until you turn off those doofers on the center pedestal, and the old cut-out switch on the yoke doesn't work like it did on the thousands of 737 planes before, and... and...

BEAM ME UP!

And some dweeb blames the pilots for not being Chuck Yeager clones and reacting to a new characteristic of the plane within a few seconds?
I will bet that 99 outta 100 of 737 drivers across the globe would have handled both accidents if they knew about MCAS and how it worked and had a procedure that simply stated to turn off the trim after using the basic system to trim nose up. Leave the test pilot crapola to test pilots, and write up the entire sequence of events ( unlike the Lion crew that assumed the STS was working backwards).

Gums sends...

P.S. Show us the plots of the pitch moments versus AoA without MCAS. Hmmmmm.....


To the point, on target.

Don't hold your breath for the static stability information to be produced, it is proprietary. It's release is a lose/lose for the maker, if it shows a considerable non linearity, then we won't hear the end of the matter. If it shows negligible issues, then the whole reason for the MCAS 2.0 debacle will be seen in a poor light.

Gums assessment counterbalances Greg F & Co.s recent lambasting of the flight crews competency in the Lionair aircraft, and by default ET's. Suggest those that don't consider the impact of the situation that presented itself in the performance of the crew should try similar and see how their performance goes.

[Stribeck]

My belief is that it’s not a simple curve, but depends on some additional factors eg. thrust vs. airspeed, and extant stab setting, and has some really nasty hidden non-linearities FOR SOME PARAMETER VALUES.
In fact the pitchdown on nose down might be even more lethal than the pitch up on nose up.
Edmund

I fully agree. As I said in a previous post, I would be very interested to see the relation between the engine nacelle drag/lift forces and the CG of the aircraft.

Normally the moment arm from engine nacelle forces around the CG would be small, and the force would be expected to act BELOW the CG, thus counteracting pitch up.
Looking at the Max profile on the other hand, I would be tempted to say that the higher/forward position of the engines could cause these forces to act ABOVE the aircraft CG at high AoA, which would give a nasty non-linear feedback with AoA.

Imagine if there's a part of the envelope where the nacelle force moment arm transitions around the CG.. Maybe this happens for a combination of aft CG and high AoA. Instead of designing away the problem, B decided to block pilots from entering that part of the envelope --> MCAS.

Disclaimer* I'm a researcher in aerospace engineering mechanics (fluid/solid interaction), not a pilot.

[Grebe]

I fully agree. As I said in a previous post, I would be very interested to see the relation between the engine nacelle drag/lift forces and the CG of the aircraft.

Normally the moment arm from engine nacelle forces around the CG would be small, and the force would be expected to act BELOW the CG, thus counteracting pitch up.
Looking at the Max profile on the other hand, I would be tempted to say that the higher/forward position of the engines could cause these forces to act ABOVE the aircraft CG at high AoA, which would give a nasty non-linear feedback with AoA.

Imagine if there's a part of the envelope where the nacelle force moment arm transitions around the CG.. Maybe this happens for a combination of aft CG and high AoA. Instead of designing away the problem, B decided to block pilots from entering that part of the envelope --> MCAS.

Disclaimer* I'm a researcher in aerospace engineering mechanics (fluid/solid interaction), not a pilot.


Might I suggest a close look at

https://www.satcom.guru/2019/10/flawed-assumptions-pave-path-to-disaster.html

peter L has a half dozen links on his site relating to the whole MAX issue. Had a lot to do with his earlier background many months ago. And he was subpoened by the feds as reported in the Seattle Times around April.

AS I recall, in one of his links, he had some relative plots for yoke force etc re AOA and speed etc probably from the NG

[MechEngr]

I really doubt that, it is just more spin from Boeing's creative marketing division. Unlike Boeing, this incident does not have the possibility (however remote) of forcing Ethiopia into bankruptcy. The issues facing the government of Ethiopia are far more significant than who gets the blame for a jet crash, and if it were in fact the fault of a pilot panicking and doing the wrong thing than that would actually be a fairly simple thing for the government to shrug off, especially in a country were so many have already died in war. Mechanical failure could be either the fault of Boeing or the airline; it would be much harder for them if for example the tail had fallen off and there was a report that the plane had been involved in a ramp incident.Nobody in the United States is worried about losing an election because of the Atlas Air crash.

You are thinking in terms of money. There is a lot more at stake. No politician in the US is worried about jail for the Atlas Air crash, but then Atlas Air isn't owned by the US Government and does not represent the US to countries across the globe. It is their national pride and joy, perhaps the only institution in the country that has been a continued success. Not to mention that those evil Westerners can be a great villain.

[DaveReidUK]

Apparently Ethiopian Airlines is working closely with the investigation and withholding the CVR from the international investigation community, providing only snippets that support a particular narrative.

I'm not sure what the relevance of the "international investigation community" is.

ICAO Annex 13 is clear - only the party leading an investigation (here, the Ethiopian AIB) is authorised to release information, and it decides what will be released when, not the operator, manufacturer or any of the other parties affiliated to the investigation.

[Bend alot]

With one week left of the year Boeing has not submitted it's final fix for the MAX to the FAA for final certification.

It is now known, that Boeing have only been giving the FAA "selections" of what is required for the FAA to evaluate the aircraft for certification.

Boeing still have no idea of what is now required to get the aircraft flying - The Full Monty is required and with zero concessions, exceptions or exclusions.

Denis on your pay surly you can understand this? You and the FAA got caught with your pants down, why are you shy now?

Only one party seems embarrassed and Denis's Board is not that party.

[PEI_3721]

gums, … > fdr, # 180. :ok:
… even if flight test data was available publicly, it would be open to misinterpretation or adaptation to support whatever view was chosen.

At best we should limit ourselves to principles, which with well-argued supposition might provide greater insight to the current problems plaguing return to service, and perhaps learn from this some of the outstanding lessons relating to human performance; manage, design, manufacture, regulate, use.

Technically, stability can be viewed from many perspectives - ‘a slice of stale bread, the edges curled up’ - (https://www.pprune.org/rumours-news/628134-max-s-return-delayed-faa-reevaluation-737-safety-procedures-mk-ii-5.html#post10644955 ).
Understanding humans is more difficult; we have yet to learn that curled up bread is difficult to push into the toaster, and that the principle of starting with stale bread does not give good toast.
But then again what is ‘good’ toast; good stability, a good aircraft, pilot, manager, CEO. We might start by stating our assumptions, add (understand) supportive regulatory materials, and heed advice to defer judgements to expertise. … But what is expertise, who is an expert, … … :{ … anyone for burnt toast.

[Fly Aiprt]

With one week left of the year Boeing has not submitted it's final fix for the MAX to the FAA for final certification.

It is now known, that Boeing have only been giving the FAA "selections" of what is required for the FAA to evaluate the aircraft for certification.



What is striking, is that at an important meeting with worldwide regulators, Boeing only offered a sweeping ppt presentation.
In my limited GA certification experience, even at a preliminary meeting, we had to delve deep into the technical and reglementary aspects of our project and had to defend each point with the corresponding expert.
Makes you think as if Boeing had no idea what certification was about...

[esscee]

That is the heart of Boeing problems, nobody really knows how to correctly present information to FAA for certification any more!Be interesting to see when the 737 NOT Max flies again, fingers crossed for the paying customers of whatever airlines.

[Fly Aiprt]

That is the heart of Boeing problems, nobody really knows how to correctly present information to FAA for certification any more!

That is, provided the required information exists. What if they failed to properly document changes in design, test flight data etc. ?
Lots of "young" engineers around me, most are incapable of correctly index versions of their documents, let alone put a date in a memo....

[Avionista]

It seems to me that if EASA, or one of the other international regulators, allow the MAX to be un-grounded/certified for flight within their airspace and a MAX subsequently crashes due to a MCAS related problem, the heads of the international regulators will be 'on the block' as well as those of the FAA regulators. In these circumstances, if I was an EASA regulator I would want to see for myself how the MAX performs at high AoA, without MCAS, before clearing the aircraft for flight within my jurisdiction. I would not be prepared to accept at face value any assurances given by the FAA or Boeing, if my job or reputation was on the line.

There are currently a number of 737-8 MAX aircraft located within EASA territory (TUI have 6). Could EASA regulators get their hands on one of these, take it to a test facility (e.g. Boscombe Down) and conduct their own 'bare airframe' tests to ensure there are no nasty surprises as far as MAX pitch stability is concerned? With a bit of temporary re-wiring of flap position input, it should be possible to fool the MAX computer into thinking the flap is down (when in fact the wings are 'clean') thereby disabling MCAS. This would allow the test pilots to explore the MAX flight envelope at high AoA in a 'bare airframe' configuration.

Surely, such due diligence is not too much to ask for from EASA to ensure the lives of European passengers are not exposed to undue risk. I'm not suggesting that EASA should conduct comprehensive re-certification flight tests, only an exploration of those aspects of the MAX flight characteristics which led to the introduction of MCAS.

[Fly Aiprt]

Could EASA regulators get their hands on one of these, take it to a test facility (e.g. Boscombe Down) and conduct their own 'bare airframe' tests to ensure there are no nasty surprises as far as MAX pitch stability is concerned? With a bit of temporary re-wiring of flap position input, it should be possible to fool the MAX computer into thinking the flap is down (when in fact the wings are 'clean') thereby disabling MCAS. This would allow the test pilots to explore the MAX flight envelope at high AoA in a 'bare airframe' configuration.

Clever rewiring idea. Could be used as a band-aid to allow the airplane to permanently fly sans MCAS.
Not sure using a revenue airplane for flight testing might be authorized, though. Better leave Boeing do the rewiring and first test flights and foot the bill ;-)
Also a test flight facility on the continent might prove more adequate, since Boscombe Down will no longer be in the EU in 38 days from now...

[KCode]

PPT is no substitute for hard technical facts. My aging memory tells me that the NASA seniors relied extensively on ppt when trying to decide of the foam strike on the Columbia was of any concern. =left"A Washington Post article (August 30, 2005) on PowerPoint’s influence on Space Shuttle disasters stated;
“Exhibit A in Tufte’s analysis is a PowerPoint slide presented to NASA senior managers in January 2003, while the space shuttle Columbia was in the air and the agency was weighing the risk posed by tile damage on the shuttle wings. Key information was so buried and condensed in the rigid PowerPoint format as to be useless.”“It is easy to understand how a senior manager might read this PowerPoint slide and not realize that it addresses a life-threatening situation,” the Columbia Accident Investigation Board concluded, citing Tufte’s work.

[gums]

Salute!

Thanks for the input, PEI
OTOH, we see many raw data flight data recorder traces and have had super analysis amongst us, especially on the Tech Log. So seeing the data is not without precedent here, although the masses that read the New York Slime would not have a clue ( as they do not about many things)

My point and maybe Stri and FDR and Edmund , et al be that the plane may be just fine at idle thrust versus high thrust or even cruise settings. How bad is the linearity? And I do not believe "Peter" has the actual plots from flight test data, Finally, the change to the amount of stab movement, etc after the initial implementation is, or should be, of interest to all of us.

And "all of us" includes old farts like me that are now only SLF. As a SLF I once got a free bottle of champaign from the Western airline crew ( back a long time ago before being absorbed) for commenting to nearby SLF that the crack maintenance folks were repairing a hydraulic leak on the left main gear brakes. We had to delay about a half hour, and the nearby SLF were getting restless, heh heh. Crew told me that my commentary helped calm down the SLF and made things easier for all.

I may only be a knowledeable piece of SLF nowadays, and it scares me more than the average piece sitting next to me when I see what this MCAS debacle has wrot.

Gums sends, and Merry Christmas to all!!!!

[Takwis]

Merry Christmas indeed, Gums. I'd love to have you on my plane, explaining everything to the Pax.

[PEI_3721]

Yo gums, whilst your alternative approach would be feasible, Pprune analysis is irrelevant in judging and approving the Max to fly again - just satisfying our need to understand or learn, each of us differently.
‘We’ don’t certificate aircraft; we trust someone else to do that, which in this instance that trust has been strained. It is doubtful that self-Pprune assessment would improve that trust because trust depends on more than data, it involves process, time, and unquantifiable human attributes of ability, reliability, integrity, etc.

FDR accident analysis is an evaluation of what occurred, judged against what was expected for an aircraft with known, ‘certificated’ characteristics.
Flight test analysis requires detailed and a larger range of data, it involves judgement of something new against requirements.

The certification arguments for MCAS were flawed, but the principles were proven in flight test, certification, and subsequently commercial operations. MCAS worked as designed; however history shows that the supporting design was not fail safe, nor in that sense, were the interpretations, judgements, and approvals in the regulatory process; both systemic failures.

The basic unaided Max does not meet requirements, but arguably the aircraft can be flown without MCAS as an abnormal operation - not for commercial use excepting continued safe flight and landing. If this was not so then the ‘bent tin and rivets’ would be visible by now.

What appears to be of continuing concern is the transition from normal MCAS aided flight to abnormal unaided flight. Again, arguably, this is does not involve inhibiting MCAS - automatic fail safe, but the issues associated with the cause of the shutdown and crew interaction - managing consequences, distractions, ambiguities. These are uniquely certification judgements, and not quantifiable with data.

There may also be other issues not considered in the original certification - ‘because it’s the same as the NG’, which the Max is not - the realisation and acceptance of this by the ‘trusting’ authorities - let’s look again.
The aerodynamic differences could challenge the assumptions made for managing trim runaway, or adverse MCAS influence or manual trim use during upset conditions - speculation, but consider issues arising from recent NG accidents.
Then there is training, required experience, same type rating, etc, just as significant as aerodynamic design and system reliability.

Happy Christmas; but don’t expect any Max test data in your stocking.

[OldnGrounded]

Happy Christmas; but don’t expect any Max test data in your stocking.

Whether or not test data on, e.g., stability can be withheld from the public as proprietary is not a settled question. I very much doubt that, in the long run, the answer will be that it can. The public interest in that data will very likely be seen by the courts as outweighing any proprietary interest.

And Boeing and the FAA should probably consider that, whatever the data may demonstrate, waiting to divulge it until forced to do so can only magnify the damage to the company and regulator.

[turbidus]

Clever rewiring idea. Could be used as a band-aid to allow the airplane to permanently fly sans MCAS.
Not sure using a revenue airplane for flight testing might be authorized, though. Better leave Boeing do the rewiring and first test flights and foot the bill ;-)

pretty sure there is only one test aircraft, BOE1. It likely has quite o bit of testing hardware installed.

Once the 'fix" has been installed, there will be flight testing of each revenue aircraft, especially by the Airline Chief...details unknown at this time.

Whether or not test data on, e.g., stability can be withheld from the public as proprietary is not a settled question. I very much doubt that, in the long run, the answer will be that it can.

I am sure it will be withheld, just like FOQA/FDM/FDA data...

[Takwis]

Once the 'fix" has been installed, there will be flight testing of each revenue aircraft...

The FAA has promised they would "certify" every aircraft. I haven't seen anything written about them actually flying each airplane. I envision something more mundane...checking for the latest software update, and signing the airworthiness certificate.

The FAA will retain authority to issue airworthiness certificates and export certificates of airworthiness for all new 737 MAX airplanes manufactured since the grounding.
Stephen M. Dickson, Before the Committee on Transportation and Infrastructure, United States House of Representatives
December 11, 2019

[OldnGrounded]

I am sure it will be withheld, just like FOQA/FDM/FDA data...

Information on aerodynamic stability of the aircraft is very different in kind from those. Think about it this way:

An automobile manufacturer could properly treat information about the details of its traction control or antilock braking systems as proprietary, but there's no way it could get away with refusing to release test track data on stopping distance or rollover characteristics -- certainly not in the context of lawsuits in the wake of crashes raising questions about those characteristics.

Edit: And nothing could prevent interested third parties from conducting independent testing and releasing the results, so attempting to keep them secret in the midst of controversy could only further damage corporate credibility and public image.

[The AvgasDinosaur]

Merry Christmas indeed, Gums. I'd love to have you on my plane, explaining everything to the Pax.
I’d be even happier to have him in seat 0A on my flight👍
David

[Grebe]

Golly NOW Boeing will supply some long delayed documents ??



More ‘troubling’ internal Boeing documents on 737 MAX set for release
Dec. 23, 2019 at 2:18 pm Updated Dec. 23, 2019 at 2:24 pm
By Dominic Gates
and Steve Miletich

Boeing has informed the Federal Aviation Administration (FAA) that its internal investigation into development of the 737 MAX has turned up more “troubling communications” that the company’s lawyers say it needs to disclose, according to a person familiar with the details.

Though the implication is that the documents contain damaging information, Boeing has not yet sent them to the FAA or to the Congressional committees that are investigating the MAX crashes.

“The FAA is aware of the documents and is waiting for Boeing to turn them over,” said the person.

Boeing is expected to release the documents as early as today. The timing of such a move, so close to the holidays and on the same day as the sacking of CEO Dennis Muilenburg, might be intended to get the bad news out there all at once with less press coverage.

Several sources suggest the documents include further messages from Mark Forkner, the 737 Chief Technical Pilot during the development of the MAX. Forkner’s job was to test the MAX flight control systems in a simulator and to determine the information and training that pilots would need to fly the airplane.

It was Forkner who sent an email to an FAA official in March, 2016, asking that information about the MAX’s new flight control software—known as the Maneuvering Characteristics Augmentation System (MCAS)—be omitted from the pilot manuals and not mentioned in pilot training.

In October, a 2016 instant message exchange between Forkner and another Boeing pilot was released in which Forkner stated that he had “basically lied to the regulators (unknowingly).”

In that loose conversation, during which Forkner was drinking vodka, he said MCAS had “run rampant” during simulator testing in 2016. Boeing said later he was referring to the simulator software being defective rather than MCAS itself.

And in a separate 2016 email to an FAA official, Forkner joked that he was “doing a bunch of traveling … jedi-mind tricking (foreign) regulators into accepting the training that I got accepted by FAA.”

These revelations produced outrage and were the subject of intense questioning of Muilenburg when he appeared before Congress in late October.

[OldnGrounded]

Golly NOW Boeing will supply some long delayed documents ??

Latest update on the Seattle Times site (https://www.seattletimes.com/business/boeing-aerospace/more-troubling-internal-boeing-documents-on-737-max-set-for-release/) says they have been sent to FAA today:

Boeing has sent the Federal Aviation Administration (FAA) documents that were discovered by its internal investigation into development of the 737 MAX and that include “troubling communications” that the company’s lawyers say it needs to disclose, according to a person familiar with the details.

The documents include further messages from Mark Forkner, the Boeing pilot whose 2016 instant message exchange with a colleague caused outrage when it was released in October.Boeing will also send the documents, which are understood to contain damaging information, to the Congressional committees that are investigating the MAX crashes.

The timing of the disclosure, so close to the holidays and on the same day as the sacking of CEO Dennis Muilenburg, might be intended to get the bad news out there all at once with less press coverage.

[turbidus]

AFTER all this time, they "FIND" documents that show troubling and further communications with Forkner?????

You can do a word search for "Forkner" and find them all????

what sort of software do the run there??? (oh...never mind)

Isnt lying to Congress an offense?

[Grebe]

" Isnt lying to Congress an offense?"

Depends on who gets tagged with " lack of candor"

Boeing is now searching for the Janitor who misplaced the ' documents' or forgot to keep the shredder turned on

[edmundronald]

Salute!

Thanks for the input, PEI
OTOH, we see many raw data flight data recorder traces and have had super analysis amongst us, especially on the Tech Log. So seeing the data is not without precedent here, although the masses that read the New York Slime would not have a clue ( as they do not about many things)

My point and maybe Stri and FDR and Edmund , et al be that the plane may be just fine at idle thrust versus high thrust or even cruise settings. How bad is the linearity? And I do not believe "Peter" has the actual plots from flight test data, Finally, the change to the amount of stab movement, etc after the initial implementation is, or should be, of interest to all of us.

And "all of us" includes old farts like me that are now only SLF. As a SLF I once got a free bottle of champaign from the Western airline crew ( back a long time ago before being absorbed) for commenting to nearby SLF that the crack maintenance folks were repairing a hydraulic leak on the left main gear brakes. We had to delay about a half hour, and the nearby SLF were getting restless, heh heh. Crew told me that my commentary helped calm down the SLF and made things easier for all.

I may only be a knowledeable piece of SLF nowadays, and it scares me more than the average piece sitting next to me when I see what this MCAS debacle has wrot.

Gums sends, and Merry Christmas to all!!!!

Gums,
Math jargon Sri’s , “may exhibit non-linear feedback” is the engineer’s equivalent of saying may become EXTREMELY unpredictable.

- one wants a system to be controllable - ie can be brought/forced to a desired eg. nice stable state starting from any state inside the envelope.
- if the system is “linear” then a branch of engineering maths called LINEAR control theory applies, the domain where it is controllable is known, and eveything is “copacetic”, automation can be easily used, and the system may be approved on the virtues of its design.
- if the system is “non-linear” and even worse if it exhibits non-linear feedback, then can as they say in the US it can “go postal”, and standard school maths can’t describe it nor control it. An auditor won’t certify such a system unless it is extensively tested -if the auditor be honest. And automation can be very unhappy about the surprises baked into such a unpredictable system.

The suspicion is that MCAS is there to keep the MAX centered in an envelope where it appears linear, but that without MCAS it might get into states where it would be really hard to control (except for Chuck Yeager and you). The unfortunate joke is that the extant MCAS took several airframes into states where they were hard to control. Of course one could argue one can always deviate into a non-linear behaviour eg. stall, but the suspicion here is that the volume of linearity is more limited than it should be, and that really ugly things happen in places where certified airframes should still be acting nice.

I’m sorry if the above is erroneous or unclear, my opinions are usually worth exactly what people are paying for them.

Merry Xmas

[ktcanuck]

Gums,
Math jargon Sri’s , “may exhibit non-linear feedback” is the engineer’s equivalent of saying may become EXTREMELY unpredictable.

- one wants a system to be controllable - ie can be brought/forced to a desired eg. nice stable state starting from any state inside the envelope.
- if the system is “linear” then a branch of engineering maths called LINEAR control theory applies, the domain where it is controllable is known, and eveything is “copacetic”, automation can be easily used, and the system may be approved on the virtues of its design.
- if the system is “non-linear” and even worse if it exhibits non-linear feedback, then can as they say in the US it can “go postal”, and standard school maths can’t describe it nor control it. An auditor won’t certify such a system unless it is extensively tested -if the auditor be honest. And automation can be very unhappy about the surprises baked into such a unpredictable system.

The suspicion is that MCAS is there to keep the MAX centered in an envelope where it appears linear, but that without MCAS it might get into states where it would be really hard to control (except for Chuck Yeager and you). The unfortunate joke is that the extant MCAS took several airframes into states where they were hard to control. Of course one could argue one can always deviate into a non-linear behaviour eg. stall, but the suspicion here is that the volume of linearity is more limited than it should be, and that really ugly things happen in places where certified airframes should still be acting nice.

I’m sorry if the above is erroneous or unclear, my opinions are usually worth exactly what people are paying for them.

Merry Xmas
If you are saying that MCAS was a brute force way of stopping the Max getting into a [secret] corner of the envelope that was nasty but ended up, through some failure, putting the poor souls into a different nasty situation, I agree entirely.

[edmundronald]

If you are saying that MCAS was a brute force way of stopping the Max getting into a [secret] corner of the envelope that was nasty but ended up, through some failure, putting the poor souls into a different nasty situation, I agree entirely.

Yes. And we’re saying we believe that the envelope where the MAX is natively nice is too small to allow it to be certified, and this is what Boeing is hiding with passive collusion from the FAA. If -when - international certification authorities do tests without MCAS, the deficiencies will become apparent, and goodbye certification. My guess - I’m just a random SLF- is that civilian airliners that are flown by standard pilots are supposed to have very forgiving aerodynamics, and large time constants, and that as soon as AoA climbs strongly or goes negative and the nacelle effects come into play there is nothing forgiving about this airframe any more.

The answer to this question would be provided by flight test data without MCAS. I think that at this point certification without this data being published is not feasible, at least outside the US.

Also, I would think that any pilot who gets into a MAX at this point should demand to know the real intended function of MCAS. It’s possible that at high AoA, elevator authority effects are very substantially different from the NG, which is why MCAS was redesigned to react fairly strongly. Please take this with a large grain of salt, I am not a pilot.


Edmund

[MechEngr]

I'm not sure what the relevance of the "international investigation community" is.

ICAO Annex 13 is clear - only the party leading an investigation (here, the Ethiopian AIB) is authorised to release information, and it decides what will be released when, not the operator, manufacturer or any of the other parties affiliated to the investigation.

That would be public releases, not to withhold information from other investigative agencies in the ICAO.

[George Glass]

Curious that the initial report on the Ethiopian accident has been removed from the ecaa.gov.et website. Anyone know where its gone ?

[MechEngr]

Yes. And we’re saying we believe that the envelope where the MAX is natively nice is too small ...

Also, I would think that any pilot who gets into a MAX at this point should demand to know the real intended function of MCAS. It’s possible that at high AoA, elevator authority effects are very substantially different from the NG, which is why MCAS was redesigned to react fairly strongly. Please take this with a large grain of salt, I am not a pilot.

Edmund

An airplane in flight is essentially a teeter-totter balanced on the Center of Pressure (CP) for the entire airplane and is considered to be the point where the lift acts. One element of this is that lift from positive AoA produces a nose-down pitch torque. To counter that, the horizontal stabilizer produces a nose up pitch torque by pushing down on the aft end of the fuselage. When these are balanced everyone is happy, or at least the AoA isn't changing. Of note is that the stabilizer functions as a wing that produces lift opposite to the lift of the wing and has its own local AoA.

If one looks at all possible stable AoAs one would like to see a linear relation between the AoA of the wing and the stabilizer trim position required to balance it. But the Max seems to have another player on the teeter-totter and that is the nacelle of the engine which starts producing noticeable nose up pitch torque at high AoA. So the stab trim position is no longer quite as linear as it was. Since the elevator also affects the pitch torque, that's where the effect could be noticed by the pilot as they move the controls without adjusting the trim. The function of MCAS is to make it so the pilot doesn't experience this new player.

Because it's just to offset the new player and depends on AoA and airspeed (because the amount of lift the stabilizer produces depends on those things to generate nose-up torque) it really isn't moving much or fast; it just has to be fast enough to keep up with AoA changes to the aircraft and to speed changes, neither of which ought to be particularly high. It gets more pronounced at low speeds because not only does the requisite high AoA needed to provide lift at low speeds increase the effect from the engine nacelles, the lower speed also means the stabilizer has less dynamic pressure to work with. This is no different than, say, rudder authority at low speed; the rudder has to move a lot farther to get the same effect at low speed than high speed.

AFAIK that's the intended MCAS function. To meet a linearity requirement for pilot controls by rebalancing a larger input from the engine nacelles than was existent, but could be ignored, on earlier models. It's not fast enough for a negative stability situation, so that's not it.

[MechEngr]

Curious that the initial report on the Ethiopian accident has been removed from the ecaa.gov.et website. Anyone know where its gone ?

Maybe the link is gone; where did you look that you did not find it? Not sure if I get to post links:
http://www.ecaa.gov.et/Home/wp-content/uploads/2019/07/Preliminary-Report-B737-800MAX-ET-AVJ.pdf

[edmundronald]

An airplane in flight is essentially a teeter-totter balanced on the Center of Pressure (CP) for the entire airplane and is considered to be the point where the lift acts. One element of this is that lift from positive AoA produces a nose-down pitch torque. To counter that, the horizontal stabilizer produces a nose up pitch torque by pushing down on the aft end of the fuselage. When these are balanced everyone is happy, or at least the AoA isn't changing. Of note is that the stabilizer functions as a wing that produces lift opposite to the lift of the wing and has its own local AoA.

If one looks at all possible stable AoAs one would like to see a linear relation between the AoA of the wing and the stabilizer trim position required to balance it. But the Max seems to have another player on the teeter-totter and that is the nacelle of the engine which starts producing noticeable nose up pitch torque at high AoA. So the stab trim position is no longer quite as linear as it was. Since the elevator also affects the pitch torque, that's where the effect could be noticed by the pilot as they move the controls without adjusting the trim. The function of MCAS is to make it so the pilot doesn't experience this new player.

Because it's just to offset the new player and depends on AoA and airspeed (because the amount of lift the stabilizer produces depends on those things to generate nose-up torque) it really isn't moving much or fast; it just has to be fast enough to keep up with AoA changes to the aircraft and to speed changes, neither of which ought to be particularly high. It gets more pronounced at low speeds because not only does the requisite high AoA needed to provide lift at low speeds increase the effect from the engine nacelles, the lower speed also means the stabilizer has less dynamic pressure to work with. This is no different than, say, rudder authority at low speed; the rudder has to move a lot farther to get the same effect at low speed than high speed.

AFAIK that's the intended MCAS function. To meet a linearity requirement for pilot controls by rebalancing a larger input from the engine nacelles than was existent, but could be ignored, on earlier models. It's not fast enough for a negative stability situation, so that's not it.

MechEngr,

You have very cogently made the case -by reasoning- for the need for something like MCAS; of course if a new force is introduced it would be desirable to offset it if one wishes to use an extant control model.
However you haven't really explored the issues which lead to this need, in other words what piloting a MAX without MCAS would look like.

Also it is not at all obvious -in fact extremely improbable- that a given control model can be perfectly grafted on a different airframe by means of a simple mechanical accessory. Of course one could make the case that the mechanical aid creates a similar linearised behavior around equilibrium, bu it would still be required to demonstrate that the relinearised zones share the same volumes of state space, and that these volumes are the only regimes which are of practical importance during flight. Hence it would be very difficult to demonstrate by maths alone, without extensive testing that the MAX shares a control model with the NG and thus can share its certification. There is no evidence to date of the results of such testing.

My understanding that under current regulatory règimes for civilian aircraft, acceptance of the airframe design WITH MCAS is conditioned on the behavior WITHOUT MCAS. Namely if without MCAS the airframe cannot be flown easily ie. can tend to stall or dive or do other wierd things, then the design would be classed as necessitating active control (MCAS) and couldn't be certified. Which is why Boeing so prudently talks of "linearizing" stick feel.

I continue to believe that in a rush to acquire a grandfathered certification, Boeing was overly economical with the truth in its descriptions of the 737 dynamics, which explains Boeing's reluctance to reveal the exact design goals of MCAS.


Most of the pilot readers here would appear to have no issue with MCAS certification if it were "just" a stick-pusher, but if it is a more complex entity as now seems likely, then a more careful certification process seems necessary.

Edmund

[MechEngr]

MechEngr,

You have very cogently made the case -by reasoning- for the need for something like MCAS; of course if a new force is introduced it would be desirable to offset it if one wishes to use an extant control model.
However you haven't really explored the issues which lead to this need, in other words what piloting a MAX without MCAS would look like.

Also it is not at all obvious -in fact extremely improbable- that a given control model can be perfectly grafted on a different airframe by means of a simple mechanical accessory. Of course one could make the case that the mechanical aid creates a similar linearised behavior around equilibrium, bu it would still be required to demonstrate that the relinearised zones share the same volumes of state space, and that these volumes are the only regimes which are of practical importance during flight. Hence it would be very difficult to demonstrate by maths alone, without extensive testing that the MAX shares a control model with the NG and thus can share its certification. There is no evidence to date of the results of such testing.

My understanding that under current regulatory règimes for civilian aircraft, acceptance of the airframe design WITH MCAS is conditioned on the behavior WITHOUT MCAS. Namely if without MCAS the airframe cannot be flown easily ie. can tend to stall or dive or do other wierd things, then the design would be classed as necessitating active control (MCAS) and couldn't be certified. Which is why Boeing so prudently talks of "linearizing" stick feel.

I continue to believe that in a rush to acquire a grandfathered certification, Boeing was overly economical with the truth in its descriptions of the 737 dynamics, which explains Boeing's reluctance to reveal the exact design goals of MCAS.


Most of the pilot readers here would appear to have no issue with MCAS certification if it were "just" a stick-pusher, but if it is a more complex entity as now seems likely, then a more careful certification process seems necessary.

Edmund

The question is about what it would feel like. I think it would feel as much like an NG at a similar load as anything because pilots spend so little time at high AoA and also little time hand flying that they have no good basis for comparison. We already have record of a flight without MCAS in the first Lion Air situation non-crash flight. The pilots made no comment on any difficulty of hand flying besides the obvious loss of electric trim.

You cannot use a stick pusher to change the balance of aerodynamic forces on the the plane, which MCAS does and a stick pusher does not. And if that stick pusher had the same authority to apply full-down elevator with as much force on the column as MCAS produced because, for the same AoA system malfunction, the controls felt the plane was in a deep stall, there would still be the same crashes.

[Capn Bloggs]

The question is about what it would feel like. I think it would feel as much like an NG at a similar load as anything because pilots spend so little time at high AoA and also little time hand flying that they have no good basis for comparison. We already have record of a flight without MCAS in the first Lion Air situation non-crash flight. The pilots made no comment on any difficulty of hand flying besides the obvious loss of electric trim.
They were nowhere near the corner of the flight envelope where MCAS (normally) operates.

[edmundronald]

The question is about what it would feel like. I think it would feel as much like an NG at a similar load as anything because pilots spend so little time at high AoA and also little time hand flying that they have no good basis for comparison. We already have record of a flight without MCAS in the first Lion Air situation non-crash flight. The pilots made no comment on any difficulty of hand flying besides the obvious loss of electric trim.

You cannot use a stick pusher to change the balance of aerodynamic forces on the the plane, which MCAS does and a stick pusher does not. And if that stick pusher had the same authority to apply full-down elevator with as much force on the column as MCAS produced because, for the same AoA system malfunction, the controls felt the plane was in a deep stall, there would still be the same crashes.

The question is what it flies like, not what it feels like. MCAS may re-linearise MAX to resemble NG in normal flight, but we don't know when and whether the behavior of Max can depart from that of the NG.

A good example of this might be stall onset and deep stall recovery. Are they the same?

Another nastier example is recovery from a strong accidental pitchdown.


We can continue to argue this forever; it'll only be put to rest when either Boeing publishes the data, a non-us regulator rebels and does a test flight, or someone constructs a detailed aerodynamical simulation of the Max.

Edmund

[fdr]

...The suspicion is that MCAS is there to keep the MAX centered in an envelope where it appears linear, but that without MCAS it might get into states where it would be really hard to control (except for Chuck Yeager and you). The unfortunate joke is that the extant MCAS took several airframes into states where they were hard to control.

I’m sorry if the above is erroneous or unclear, my opinions are usually worth exactly what people are paying for them...

Merry Xmas

I suspect that in the fullness of time, when modelling of the flow is conducted by some august body with unsteady modelling code, that the effect of the cowling will end up being noticeable but not significant in itself, that MCAS the cure is worse than the risk that it protects against. My estimate is that it will not have ever resulted in an unstable condition, that the underlying effect was notchiness of the nacelle acting as a lifting body with vortex structures over the wing, and that the vortex interaction on the wing is a more significant component of the pitching moment; the combined effects of planform increase forward of the cg, vortex structures over the wing increasing lift inboard (forward shift of Cp and reducing Cm on a swept wing) and increased downwash at the tail from the inner section of the wing arising from the nacelle vortex interaction with the wing at high AOA. With all of those effects, still suspect that the total effect was modest and never resulted in a pitch up. I'll wager USD100 on that to the first DNS/LES modelling that shows differently.

All that really means, the cure may well have been far worse than the symptom.

[xetroV]

The certification arguments for MCAS were flawed, but the principles were proven in flight test, certification, and subsequently commercial operations. MCAS worked as designed; however history shows that the supporting design was not fail safe, nor in that sense, were the interpretations, judgements, and approvals in the regulatory process; both systemic failures.
Are there any records of MCAS firing up as designed during actual commercial operations? I wonder how an aircrew that somehow finds itself in the part of the flight envelope where MCAS would be activated would react to the sudden (presumably unexpected) automatic nose-down trim correction. MCAS may work as designed in that case, but what about the startled human element?

[infrequentflyer789]

AFTER all this time, they "FIND" documents that show troubling and further communications with Forkner?????

You can do a word search for "Forkner" and find them all????

what sort of software do the run there??? (oh...never mind)


Careful, the wording used was "additional documents that were discovered by its internal investigation ... that the company’s lawyers say it needs to disclose".

The finding may have been done long ago, the "need to disclose" may be the recent change. Finding (electronic) documents is relatively easy, can be done with software. Deciding which documents you "need to disclose" or which documents are protected from disclosure or even may not be disclosed, is a lot harder, cannot be done (in most cases) with software, and requires wetware. Expensive, legal, wetware.

There is also a high stakes poker game going on between Boeing, Forkner and Justice Dept. / investigators. Forkner plead the fifth, clearly implying he has something to hide, something to sell, and something to gain from immunity - but no one knows what, maybe it's all a bluff. Boeing has to guess, because Forkner apparently isn't using Boeing legal counsel (no **** sherlock...) - which means they can't be sure if he is going to helpfully fall on his sword or come round behind them and stab them with it.

[fdr]

Are there any records of MCAS firing up as designed during actual commercial operations?

Doubt it. Had there been, it would have been extenuating to the implementation of MCAS, so would have come to light to mitigate the decisions that were made.

[petit plateau]

The non-linearity issue was brought up by FCEng84 way back when the whole thing started in one of the now-closed threads. It is the stick force reversal and instability that are speculations, and came later.

That poster was usually a very reliable and well-informed source. Unfortunately he hasn't posted for a very long time (probably the price for being too well-informed).

A few of us commented on the issue regarding trimming non-monotonic curves at the time. The wise old pilots ignored. So we shut up.

[DaveReidUK]

Are there any records of MCAS firing up <em>as designed</em> during actual commercial operations? I wonder how an aircrew that somehow finds itself in the part of the flight envelope where MCAS would be activated would react to the sudden (presumably unexpected) automatic nose-down trim correction. MCAS may work as designed in that case, but what about the startled human element?I'd guess that deployment of MCAS for real would result in at least an ASR.

Last time I did a search of NASA's ASRS, there weren't any reports of such.

[JPcont]

Gums,
Math jargon Sri’s , “may exhibit non-linear feedback” is the engineer’s equivalent of saying may become EXTREMELY unpredictable.

- one wants a system to be controllable - ie can be brought/forced to a desired eg. nice stable state starting from any state inside the envelope.
- if the system is “linear” then a branch of engineering maths called LINEAR control theory applies, the domain where it is controllable is known, and eveything is “copacetic”, automation can be easily used, and the system may be approved on the virtues of its design.
- if the system is “non-linear” and even worse if it exhibits non-linear feedback, then can as they say in the US it can “go postal”, and standard school maths can’t describe it nor control it. An auditor won’t certify such a system unless it is extensively tested -if the auditor be honest. And automation can be very unhappy about the surprises baked into such a unpredictable system.

The suspicion is that MCAS is there to keep the MAX centered in an envelope where it appears linear, but that without MCAS it might get into states where it would be really hard to control (except for Chuck Yeager and you). The unfortunate joke is that the extant MCAS took several airframes into states where they were hard to control. Of course one could argue one can always deviate into a non-linear behaviour eg. stall, but the suspicion here is that the volume of linearity is more limited than it should be, and that really ugly things happen in places where certified airframes should still be acting nice.

I’m sorry if the above is erroneous or unclear, my opinions are usually worth exactly what people are paying for them.

Merry Xmas
I consider this a bit too simplified approach. Basically every real world control loop is more or less non-linear. Yet, typically the control design is based on the linear analysis. However, the design rules includes stability margin. This stability margin is related to the Lyapunov stability analysis.

On the other hand, even the linear system might have uncontrollable and unobservable states. In a closed loop system, there tends to be observability problems that restricts the the usability of the closed loop data.

If we consider MAX case, there are two independent feedback controllers: the pilot and the MACS. So both of them have to operate with restricted information. I see this as the root cause of the problems. When the system starts to work in an unpredictable way the failure analysis might become unreliable.

I don’t understand why the MAX is still grounded. The control problems should be relatively easy to solve (with additional actuators) when the understanding of the underlying problem is present.

My guess is that MACS was used to fix something else that stick force problem (in the control engineering referenced as open loop gain). My guess is that the system was there to prevent to enter to a envelope where the the real problems begins. For the political reasons it was named and defined to system that makes the “feeling” like NG.

My guess is that the problem were solved if the politics, the "salesman's lies” and the lawyer advices were were forgotten and the raw engineering job from clean table were started. Some kind of spoiler in the wing root or somewhere near the pylon might be needed. There should be courage to think out of the box and forget the short term costs.

[hec7or]

I'd guess that deployment of MCAS for real would result in at least an ASR. L

time I did a search of NASA's ASRS, there weren't any reports.

A real activation of MCAS as designed, would be almost imperceptible to crew, (I've seen it demonstrated in the MAX simulator) - eg; during flapless maneuvering at low IAS/High AoA where MCAS will activate momentarily and cease activation as soon as AoA reduces to design limits- much like a speed trim correction. It may well have activated many times without any crew being aware of its operation.
I think what is meant here is a runaway MCAS activation following AoA sensor failure, - an erroneous activation which will not stop trimming as the perceived AoA would not reduce even when trim reaches the forward limit, because the sensor has failed, which Boeing mistakenly assumed would be recognised as a trim runaway.

[clearedtocross]

An airplane in flight is essentially a teeter-totter balanced on the Center of Pressure (CP) for the entire airplane and is considered to be the point where the lift acts. One element of this is that lift from positive AoA produces a nose-down pitch torque. To counter that, the horizontal stabilizer produces a nose up pitch torque by pushing down on the aft end of the fuselage. When these are balanced everyone is happy, or at least the AoA isn't changing. Of note is that the stabilizer functions as a wing that produces lift opposite to the lift of the wing and has its own local AoA.

If one looks at all possible stable AoAs one would like to see a linear relation between the AoA of the wing and the stabilizer trim position required to balance it. But the Max seems to have another player on the teeter-totter and that is the nacelle of the engine which starts producing noticeable nose up pitch torque at high AoA. So the stab trim position is no longer quite as linear as it was. Since the elevator also affects the pitch torque, that's where the effect could be noticed by the pilot as they move the controls without adjusting the trim. The function of MCAS is to make it so the pilot doesn't experience this new player.

Because it's just to offset the new player and depends on AoA and airspeed (because the amount of lift the stabilizer produces depends on those things to generate nose-up torque) it really isn't moving much or fast; it just has to be fast enough to keep up with AoA changes to the aircraft and to speed changes, neither of which ought to be particularly high. It gets more pronounced at low speeds because not only does the requisite high AoA needed to provide lift at low speeds increase the effect from the engine nacelles, the lower speed also means the stabilizer has less dynamic pressure to work with. This is no different than, say, rudder authority at low speed; the rudder has to move a lot farther to get the same effect at low speed than high speed.

AFAIK that's the intended MCAS function. To meet a linearity requirement for pilot controls by rebalancing a larger input from the engine nacelles than was existent, but could be ignored, on earlier models. It's not fast enough for a negative stability situation, so that's not it.

Nicely explained, MechEngr, but that's the trim stability of a glider... Now add two large bonks with thrust/drag not vectored through cg and in line of flight, and you get another big factor influencing pitch moments. As we do not know in what flight regime(s) the unacceptable pitch up tendency occurs, the power (or idle drag) of the engines add to influencing factors you mentionned. What I cannot figure out - maybe some of you can - is the fact that the unwanted non-linearity does not occur with flaps/slats slightly extended.

[EDML]

I also think that MCAS was never triggered in normal airline use. Day to day flying only uses a small, benign part of the flight envelope.

However, there might be situations (e.g. escaping extreme wind shears), where the relevant part of the flight envelope is entered. Having an unpredictable handling of the aircraft in such a situation might be the trigger for the next catastrophic accident.

I think there is more to it than just unusual handling characteristics w/o MCAS.

[safetypee]

You should not expect to find any records of MCAS activation; they are not hazardous, exceptional, nor of interest unless the aircraft approaches an already identified safety boundary.
The design was intended to be a background operation, not seen or felt by the crew other than by close observation of trim activity.
MCAS activation is no more unusual than STS operation.

[LowObservable]

MCAS can be shown to be very logical.

But regardless of the parameters that activate it, and the absence of any intuitive means to inhibit a false activation, it still seems strange to invoke the most powerful effector on the airplane as a means to adjust stick force. What happened to springs and variable linkages?

Also, let's not forget that MCAS became lethal when its authority was increased to deal with a second, lower-speed-range issue of non-linear force-to-alpha relationship. That's where someone needs to look at the "naked" characteristics - because MCAS 2.0 is more easily inhibited, increasing the chance that a MAX will enter that corner of the envelope unprotected.

[OldnGrounded]

I don’t understand why the MAX is still grounded. The control problems should be relatively easy to solve (with additional actuators) when the understanding of the underlying problem is present.

It seems likely that a solution involving additional actuators would threaten certification under the existing type certificate.

My guess is that MACS was used to fix something else that stick force problem (in the control engineering referenced as open loop gain). My guess is that the system was there to prevent to enter to a envelope where the the real problems begins.

That makes sense to lots of people who have been paying close attention to this issue.

For the political reasons it was named and defined to system that makes the “feeling” like NG.

I think the reasons are probably related to regulatory and sales and marketing issues rather than "political" ones.

My guess is that the problem were solved if the politics, the "salesman's lies” and the lawyer advices were were forgotten and the raw engineering job from clean table were started. Some kind of spoiler in the wing root or somewhere near the pylon might be needed. There should be courage to think out of the box and forget the short term costs.

I don't think there's much question about that: you're almost certainly correct. However, that approach would effectively kill the MAX and be disastrous for Boeing's standing in the narrowbody market. So it almost certainly won't happen unless forces outside the company make it happen.

[Takwis]

MCAS activation is no more unusual than STS operation.

Except that it moves the trim farther, and faster, and usually in the opposite direction.

[MurphyWasRight]

Originally Posted by safetypee https://www.pprune.org/images/buttons/viewpost.gif (https://www.pprune.org/rumours-news/628134-max-s-return-delayed-faa-reevaluation-737-safety-procedures-mk-ii-12.html#post10646896)
MCAS activation is no more unusual than STS operation.
Except that it moves the trim farther, and faster, and usually in the opposite direction.

Although MCAS 1.0 was given a huge authority range in "normal" activation it would likely use much less, just enough to get AoA back where it wanted it.

Thus a normal activation might not be all that noticeable, especially given that STS is also tweaking trim although in opposite direction.

Question for 737 pilots:
Unless one was looking at the trim wheel would you even notice that a particular (short, not pathological) trim tweak was opposite the expected STS direction in a dynamic situation where MCAS would trigger?

[MechEngr]

Nicely explained, MechEngr, but that's the trim stability of a glider... Now add two large bonks with thrust/drag not vectored through cg and in line of flight, and you get another big factor influencing pitch moments. As we do not know in what flight regime(s) the unacceptable pitch up tendency occurs, the power (or idle drag) of the engines add to influencing factors you mentionned. What I cannot figure out - maybe some of you can - is the fact that the unwanted non-linearity does not occur with flaps/slats slightly extended.

MCAS does not respond to any of those things, which all commercial jets have and for which pilots already have to compensate, and aren't fundamental to understanding MCAS. Landing gear, the rudder/vertical stabilizer, flow around the fuselage, wing downwash affect on the horizontal stabilizer, cargo/passenger loads, compressability effects, et al, are complicated interactions when a simple explanation was wanted.

I expect that with flaps/slats that the pitch-down increases so much that the non-linearity contribution from the engine nacelles is back to being too small a relative contributor to notice.

[OldnGrounded]

More on the "recently-acknowledged" messages:

Boeing Discloses More ‘Very Disturbing’ Messages on 737 Max (https://finance.yahoo.com/news/boeing-discloses-set-737-max-011254203.html)(Bloomberg) -- A new batch of messages between Boeing Co. employees on the development of the 737 Max paints a “very disturbing picture” of concerns about the plane, according to an aide to a House committee.

The documents were turned over to the Federal Aviation Administration on Monday, the agency said in a statement. The disclosure came the same day that Boeing ousted its chief executive officer.

At least some of them were written by the same Boeing pilot whose 2016 messages were released in October and were the subject of sharp questioning by lawmakers, according to a person familiar with their contents who wasn’t authorized to discuss them.

The communications haven’t been released publicly. The staff of the Transportation and Infrastructure Committee are still reviewing the messages and didn’t provide specific details about what they contain.

“But similar to other records previously disclosed by Boeing, the records appear to point to a very disturbing picture of both concerns expressed by Boeing employees about the company’s commitment to safety and efforts by some employees to ensure Boeing’s production plans were not diverted by regulators or others,” a committee aide said in a statement.“

The committee will continue to review these and other records provided by Boeing as part of the committee’s ongoing investigation,” the aide said.

Boeing didn’t immediately respond to an emailed request for comment.

This was the second time that the Chicago-based company has delayed turning over to the FAA sensitive messages related to the development of the 737 Max jetliner, which was grounded in March after a design flaw was linked to two fatal crashes, in Indonesia and Ethiopia. The earlier episode prompted a rebuke by the agency and helped lead to growing tensions between the regulator and the planemaker.

The FAA didn’t comment in its statement on the content of the emails, saying only that they were under review. The company’s decision to turn the emails over to the FAA was reported earlier by the Seattle Times.

The way Boeing handled the second set of records rankled the agency, according to a person familiar with the issue who wasn’t authorized to speak about it. Boeing told the FAA the messages existed in recent days, but didn’t initially provide them or disclose their contents, said the person.

Boeing Chief Executive Officer Dennis Muilenburg stepped down on Monday, at least partly as a result of deteriorating relations with the FAA, according to a statement from the company’s board.

In October, Boeing disclosed to the FAA instant messages and emails by a high-ranking company pilot who in 2016 expressed misgivings about the software implicated in two fatal crashes on the Max.

Boeing had known about those messages since early in the year and turned them over to the Justice Department in February. It didn’t give them to the FAA immediately because of the criminal investigation into how the plane was approved, Bloomberg News reported at the time.

The delay angered the FAA, which is charged with overseeing Boeing. One of the agency’s key tenets is that entities it oversees must disclose safety issues or possible breaches of regulations. In some circumstances, failing to tell the agency about such an issue may be considered a legal violation.

“The FAA finds the substance of the document concerning,” the agency said in a statement on Oct. 18. “The FAA is also disappointed that Boeing did not bring this document to our attention immediately upon its discovery.”

The November 2016 instant messages disclosed in October, which were reviewed by Bloomberg News, were between between Mark Forkner, then Boeing’s chief technical pilot for the 737, and another 737 technical pilot, Patrik Gustavsson.

Forkner expressed concern that the flight-control feature later implicated in the crashes was “running rampant” and said he might have unknowingly misled the FAA about it. In separate emails he sent to an unnamed FAA official, he said he was “jedi-mind tricking” regulators outside the U.S. into accepting Boeing’s suggested training for the Max.

A lawyer for Forkner, David Gerger, said issues raised in the messages were the result of balky simulator software and not a result of problems with the plane itself. Forkner believed the plane was safe and didn’t mislead the FAA, Gerger said.

Gerger didn’t respond to requests to comment on the latest messages and whether they involved his client.


Emphasis added.

[Water pilot]

Boeing plans to hand out "safety" cards to convince pax that Max is safe. (https://www.nytimes.com/2019/12/24/business/boeing-737-max-survey.html)

For instance, if a traveler doesn’t want to fly after buying a ticket, getting to the airport gate or even after boarding the plane, Boeing says that the airline could offer to rebook a flight, have flight attendants or pilots talk to the concerned passenger or hand out 3-by-5 inch information cards detailing why the Max is safe... In the most extreme cases, Boeing suggests using “techniques related to an inflight medical emergency to de-escalate.

At times, the material is startlingly self-critical. In a draft memo Boeing prepared for airlines to share with employees such as flight attendants, the company suggests that airlines say: “Boeing understands that it fell short and let us down, as well as the flying public, and it has committed to continuous improvement and learning....

In a section of the presentation focused on social media and marketing, the company said it planned to “amplify any positive stories reported,” and that it intended to buy ads to promote the plane’s return to service. It said a company website dedicated to updates on the Max was being designed with “improved usability” and “stickiness” to “encourage more time on site and repeat visits,” phrases commonly used in the communications business.

The presentation said Boeing’s “digital and media team” would be “monitoring social conversations around the clock. "


If you can you should look at the "Customer Journey and Scenario map" presented in the article. Aside from the explicit sexism (the concerned passenger is a "she" in all scenarios) it is rather fascinating. For instance, "if anxious passenger is posting, then airline social care team provides information on the safety of the MAX and informs the airlines network operations center of anxious passenger, which informs flight crew, as needed."

[OldnGrounded]

Boeing plans to hand out "safety" cards to convince pax that Max is safe. (https://www.nytimes.com/2019/12/24/business/boeing-737-max-survey.html)

If you can you should look at the "Customer Journey and Scenario map" presented in the article. Aside from the explicit sexism (the concerned passenger is a "she" in all scenarios) it is rather fascinating. For instance, "if anxious passenger is posting, then airline social care team provides information on the safety of the MAX and informs the airlines network operations center of anxious passenger, which informs flight crew, as needed."

Well, that's . . . seriously creepy. Thanks for the pointer.

It looks like Boeing's not going to be comforted by the initial response to coverage of this scheme. Here's the most-recommended comment on the Times story:

I'm pretty sure we all know this is baloney. Boeing slapped a software fix on a physics problem. Nope. No way am I getting on one of these. Boeing has demonstrated more concern for short term profits than for passengers. It gutted its own technical expertise. No 3x5 card is going to make up for that. What a joke.

All the other top comments are in the same vein.

[Water pilot]

Suggestions for the 3x5 card:

The Boeing 737 Max was a perfectly safe aircraft before the first crash, which was the pilot's fault.
The Boeing 737 Max was a perfectly safe aircraft before the first second crash, which was the pilot's fault.
The Boeing 737 Max was is a completely fixed and is now a perfectly safe aircraft before the first second and the next crash which was will be the pilot's fault.

[568]

Suggestions for the 3x5 card:

The Boeing 737 Max was a perfectly safe aircraft before the first crash, which was the pilot's fault.
The Boeing 737 Max was a perfectly safe aircraft before the first second crash, which was the pilot's fault.
The Boeing 737 Max was is a completely fixed and is now a perfectly safe aircraft before the first second and the next crash which was will be the pilot's fault.

You should be their PR guru....funny but true.Merry Christmas to you and all of the readers/posters on the forum.

[LowObservable]

Suggestions for the 3x5 card:

The Boeing 737 Max was a perfectly safe aircraft before the first crash, which was the pilot's fault.
The Boeing 737 Max was a perfectly safe aircraft before the first second crash, which was the pilot's fault.
The Boeing 737 Max was is a completely fixed and is now a perfectly safe aircraft before the first second and the next crash which was will be the pilot's fault.



Merry Christmas to you!

[Fat Dog]

Boeing plans to hand out "safety" cards to convince pax that Max is safe. (https://www.nytimes.com/2019/12/24/business/boeing-737-max-survey.html)

That is quite incredible. Now I really believe the MAX is doomed.

Merry Christmas to all!

[GlobalNav]

Boeing plans to hand out "safety" cards to convince pax that Max is safe. (https://www.nytimes.com/2019/12/24/business/boeing-737-max-survey.html)



If you can you should look at the "Customer Journey and Scenario map" presented in the article. Aside from the explicit sexism (the concerned passenger is a "she" in all scenarios) it is rather fascinating. For instance, "if anxious passenger is posting, then airline social care team provides information on the safety of the MAX and informs the airlines network operations center of anxious passenger, which informs flight crew, as needed."


What will they do for the "anxious pilot?"

[GlobalNav]

Suggestions for the 3x5 card:

The Boeing 737 Max was a perfectly safe aircraft before the first crash, which was the pilot's fault.
The Boeing 737 Max was a perfectly safe aircraft before the first second crash, which was the pilot's fault.
The Boeing 737 Max was is a completely fixed and is now a perfectly safe aircraft before the first second and the next crash which was will be the pilot's fault.



Wonder what they will put on the 3x5 cards for the FAA and EASA.

[Grebe]

From piece titled Boeing 737 Pilots Focus on Modified procedures



Critically, Boeing believed an uncommanded MCAS activation would be diagnosed quickly as runaway stabilizer and
be managed by following the appropriate checklist. When the Lion Air crew did not respond in this way, Boeing and
the FAA decided a reminder of the runaway stabilizer procedure would suffice while Boeing was taking a few months
to update the MCAS software.

But the March 10, 2019, crash of Ethiopian Airlines Flight 302 was linked quickly to the MCAS as well, leading to the grounding of the MAX -aircraft MAX fleet and a deeper examination of where Boeing and the FAA had gone wrong.

Among the many findings:

The complexity of the manual trim-wheel procedure, which applies to all 737s, was not well understood.

The new 737 training modules emphasize that pilots may need to use two hands to crank the wheel during a runaway trim scenario.
*** That means it takes BOTH PILOTS ***

It also says "unloading" the stabilizer—attempting to reduce airspeed and take the counterintuitive step of not pulling bark on the yoke even though the aircraft is trimmed nose down—may be necessary to move the trim wheel.

**** JEEEZZZZZZZ ****

Which also means you are in great position to Kiss your a** goodbye !!

[Icarus2001]

The new 737 training modules emphasize that pilots may need to use two hands to crank the wheel during a runaway trim scenario.
*** That means it takes BOTH PILOTS *** I am pretty sure both pilots will have TWO hands so my calculator says ONE pilot can wind the trim wheel.

[jimtx]

From piece titled Boeing 737 Pilots Focus on Modified procedures

I believe a similar issue existed/exists with the B727. But I think the only way to get there was a concocted situation in the simulator. But it is nice to know about. I never feared, wrenching or flying that bird.

[Takwis]

I am pretty sure both pilots will have TWO hands so my calculator says ONE pilot can wind the trim wheel.

The TWO trim wheels have ONE handle, each, big enough for ONE hand.

[Bend alot]

One small snag. The handles on the trim wheels are not long enough to accommodate two hands. Only one hand will fit. The two wheels are on opposite sides of the throttle quadrant. A pilot reaching over or around the throttle quadrant will get no leverage on the handle, especially as the the handle moves through 6 o'clock. It would be a very awkward and ineffective exercise.
Two hands one pilot.
https://www.youtube.com/watch?v=aoNOVlxJmow
Two hands two pilots (19:10m)
https://www.youtube.com/watch?v=xixM_cwSLcQ

[Plumb Bob]

The pilots may in a developed case have their hands full with pulling on both control columns.

Even with MCAS itself solved, with the existing mechanical trim hardware (also for the NG), a cabin crew member might apparently need to be trained to come to the rescue and kneel over the center stand (pedestal) to help cranking the mechanical trim wheels.

Logically, another assistant will already be required to be in the vacant pilot’s seat during any absence of one pilot from the cockpit to assist with pulling on the control column just in case a serious trim problem suddenly occurs.

How much chance for the adoption and how much time for the certified training of all this?

[porkflyer]

I flew thev737 long enough to remember when it used to fall from the sky due to the rudder problem. I believe two major crashes and a few more averted by skilled pilots. It was a similar design flaw but at time there was no social media. I would say Boeing has made a terrible mistake not starting on a clean sheet with a new narrowbody aircraft instead to keep alive something designed 60 years ago. I predicted this the day I read the first time of this projectThe plane remains old, challenging to fly especially in the light of degrading piloting skills resulting from absurd rules in certain
​​​regulatory environment ( EASA) allowing pilot with as low as 200 hours type rate ( and often in pay to fly environment with poor training) de facto making of it a single pilot aircraft. I remain convinced that should the crew on both cases have been more experienced and skilled in manual flying nothing would have happened. As a passenger I would be concerned about that more than MCAS.

[George Glass]

”I remain convinced that should the crew on both cases have been more experienced and skilled in manual flying nothing would have happened. As a passenger I would be concerned about that more than MCAS.”

Agree porkflyer.

Still cant quite understand why there hasn’t been more discussion about the attempted use of the autopilot and mishandling of the autothrottle. I think it is now time to concede that expecting a crew with the experience levels of both accident crews to simultaneously complete both the Airspeed Unreliable and Runaway Stabilizer Non Normal Checklists was a bridge too far.
Hate to say it , but Airbus is right.

[Flocks]

I am pretty sure both pilots will have TWO hands so my calculator says ONE pilot can wind the trim wheel.

In a sim, not that long ago, in a trim runway scenario who went quit far, because it was really difficult for me to turn the wheel with one hand as Pilot monitoring, I told the PF (Who was pulling the yoke, plane was trimed nose down), that we should both have one hand on the yoke to pull and the other empty to trim, the 2 handle are always quit in "opposite" location on the 2 wheel, so I always understood it was designed like this, in some case to be used by the 2 pilots ... And guess what ! All worked really well and we were able to have the trim back in easy movable position ...

[Diavel]

What will they do for the "anxious pilot?"
hand him or her the exact same card😁
A very merry Christmas to all on pprune

[LowObservable]

Discussion of control forces makes me think about the second level of MCAS, where the authority was increased. Theory follows:

The stabilizer can overpower the elevators, as we know. It can also move into a position where the pilots physically cannot pull hard enough to get the required elevator deflection, or wind back the nose-down trim.

So while MCAS was originally designed to smooth out a bump or dip in the stick-force-to-alpha gradient, it evolved into a system that can block the controls and prevent the aircraft from entering a certain corner of the envelope. In short, a full-authority envelope-protection system.

And that's why a single-channel system was a disaster, and why a dual or pseudo-triplex system can't be certificated.

[BDAttitude]

Discussion of control forces makes me think about the second level of MCAS, where the authority was increased. Theory follows:

The stabilizer can overpower the elevators, as we know. It can also move into a position where the pilots physically cannot pull hard enough to get the required elevator deflection, or wind back the nose-down trim.

So while MCAS was originally designed to smooth out a bump or dip in the stick-force-to-alpha gradient, it evolved into a system that can block the controls and prevent the aircraft from entering a certain corner of the envelope. In short, a full-authority envelope-protection system.
Excellent deduction.
And that's why a single-channel system was a disaster, and why a dual or pseudo-triplex system can't be certificated.
Can't it? Even not with enough lipstick and citing "alternate means of compliance" ?
I'm still guessing it all has been agreed on and they are just fighting about documention, training and other "formalities" . Everyone needs that plane back in the air - even the Chinese.

[568]

Discussion of control forces makes me think about the second level of MCAS, where the authority was increased. Theory follows:

The stabilizer can overpower the elevators, as we know. It can also move into a position where the pilots physically cannot pull hard enough to get the required elevator deflection, or wind back the nose-down trim.

So while MCAS was originally designed to smooth out a bump or dip in the stick-force-to-alpha gradient, it evolved into a system that can block the controls and prevent the aircraft from entering a certain corner of the envelope. In short, a full-authority envelope-protection system.

And that's why a single-channel system was a disaster, and why a dual or pseudo-triplex system can't be certificated.Excellent narrative."In short, a full-authority envelope-protection system".Which could also be meant to mean "anti-stall system", which is why Boeing went out of their way to dispense with the anti-stall verbiage.