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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 6th May 2019, 00:43
  #4961 (permalink)  
 
Join Date: Apr 2019
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Originally Posted by Bend alot View Post
Sadly that day is today, and not a MCAS event as predicted.
Too soon to say. I would like to think not.
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Old 6th May 2019, 01:13
  #4962 (permalink)  
 
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Another Oops

From today's NYT:

Boeing Believed a 737 Max Warning Light Was Standard. It Wasn’t.

When Boeing began delivering its 737 Max to customers in 2017, the company believed that a key cockpit warning light was a standard feature in all of the new jets.

But months after the planes were flying, company engineers realized that the warning light worked only on planes whose customers had bought a different, optional indicator.

In essence, that meant a safety feature that Boeing thought was standard was actually a premium add-on.

Boeing detailed its initial confusion about the warning light in a statement released on Sunday, adding new details to what was already known about the flawed design and introduction of the 737 Max, its best-selling jetliner.
AOA disagree, of course. Sheesh.
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Old 6th May 2019, 01:17
  #4963 (permalink)  
 
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Originally Posted by A0283 View Post
@ 737driver

A normal (fatalities included) accident safety investigation (the path that I am trying to follow) roughly takes a year. Complex ones can take more years (the 737 rudder reversals took many more years). Your "100%" statement, if true, would make fools of the majority of accident investigators. Including US investigations. That can not be your intention.
That is not my intention. I understand that it takes time to flesh out all the details in a final accident report. However, enough information may be present during the preliminary phase that indicates the need for immediate action. The obvious example in this case is that the certificate authorities did not wait for the final report to order the grounding of the MAX. Similarly, I would argue that there is enough evidence of crew member lapses, particularly when taken together with a trend that spans airlines and airframes, that we should not wait until the ink is dry on the final report before we do something about it.

My impression is that you create (unintentional) confusion on these pages by acknowledging failures of all parties in the system (you have written an excellent short post on this a number of pages back) . But then quickly and repeatedly focussing elaborately on the failure of the pilots. Which can give the general reader the idea that you are only bashing the heads of these four guys. The style of writing (for an international audience including non-native english speakers) could also be perceived by some as a bit (unintentional) arrogant and bullying. Which is something people dont expect from a (CRM) cockpit.
As I have already stated on several occasions, while there was a definite chain of causation, the people who populate this forum only really have the power to address the remedy for one link in that chain - the crew performance. We can bash Boeing all we want, but there is not a thing said on PPRuNe that is going to have a direct effect on Boeing. Personally, I'm not into complaining just to complain. If I'm going to invest my time and energy here, I would like to think that I might just move the needle some and get a reasonable number of the professional aviators who populate this forum thinking about how they can change how they approach their flying so that future accidents may be avoided. That starts with admitting, that yes, there really is a problem with the existing standards and expectations for professional pilots.

As far as my writing style, it is what it is. I am passionate about this subject, and I'm sure it comes through. I suspect I am also a bit irritating because I am uncompromisingly presenting a message that some people just do not want to hear. Boeing did not produce a resilient aircraft in the MAX. Likewise, the current pilot training pipeline is not producing resilient aviators. When the MAX is fixed, which one of those problems are we left with?

The viewpoint that I myself try to take in this accident thread is that of trying to understand facts and doings of all the parties involved. If you take that overall view, then Boeing and FAA actions appear to be (many many facts 'pending') 'unprecedented' and 'incomprehensible' and contra the long established Boeing culture (at least before the 787) ... with the FAA having mixed reviews over the last 60 years. It would also be interesting to get more facts about the impact that airlines have had here (collaborative design is also collective involvement). Therefore it is no surprise to me, and certainly a positive sign, that there are multiple (US) investigations running in parallel. Which is rather unusual by itself though. And only getting the facts in those areas will take at least one year (the DoT IG for example for his investigation said that they normally need 1 year but in this case he expects it to be longer). I would expect the NTSB to go beyond a more 'technical' investigation and include an extensive proper 'certification process and design process' investigation. It is not only a pilot thing or design thing anymore, the credibility of a significant part of US aerospace is at stake. Considering the size of US aerospace the global system has a stake in this as well.
I have no doubt that Boeing, the FAA, and a number of airlines are going to get the colonoscopy from hell in regards to how they all basically conspired to rush this program through at maximum speed and minimum costs. There are currently armies of lawyers besieging Fortress Boeing as we speak. It is an interesting spectacle to watch, and I'm sure we will learn a lot in the process. However, as I have said before, I'm not going to dwell on Boeing because Boeing doesn't really give a crap about anything I have to say. I think my energies are better directed toward people who I might actually be able to influence.

So in your posts it would sincerely help me to better understand them, if you can make clear when you are talking about general or US standards of pilot training/hrs, or training/hrs specific to 'which' accident(s). And also, if the scope of your post covers all the parties involved or that you focus 'mainly' on the piloting aspects.
Let be absolutely clear that I think that training standards and expectations have fallen across the board. I think we get away with it better in North America because we have a deeper pool of pilots to draw from than other areas of the world. It is rare to see a new hire at my airline with less than 4,000 hours, and by that time this pilot has probably seen a lot of interesting flying that did not involve engaging the autopilot at 500' on takeoff and clicking it off at 1000' on approach, if you know what I mean. Even so, I am sometimes dismayed to how much has been removed from our sim training and how much technical information has been removed from our manuals. We supposedly have on of the best airline training and safety programs in North America, yet I continually see cracks in the foundation. I suspect this is being driven by the constant race to the bottom in terms of delivering the product at the lowest possible cost.

Last edited by 737 Driver; 6th May 2019 at 13:43.
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Old 6th May 2019, 01:19
  #4964 (permalink)  
 
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Originally Posted by OldnGrounded View Post
the company believed that a key cockpit warning light was a standard feature in all of the new jets.
Who is this "company" claiming it thought there was a light there, very convenient to use an airy fairy "company name" as an excuse.

Give us the name of the exec responsible who thought this, and what evidence they had to support it, and then tell us if it was the same exec who decided AoA redundancy wasn't required...

"companies" don't make decisions, individuals do, "companies" and they lawyers should be banned from trying to protect individuals making life and death decisions, when things go wrong.
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Old 6th May 2019, 01:31
  #4965 (permalink)  
 
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When Boeing explained to pilots in one meeting how systems on the Max worked, the company said that the disagree alert would function on the ground. In the late November meeting, Boeing told pilots for American Airlines (which had bought the add-on) that their disagree alert would have notified them of problems before takeoff.

“We were told that if the A.O.A. vane, like on Lion Air, was in a massive difference, we would receive an alert on the ground and therefore not even take off,” said Dennis Tajer, a spokesman for the union representing American Airlines pilots. “That gave us additional confidence in continuing to fly that aircraft.”

But in the last several weeks, Boeing has been saying something different. Mr. Tajer said the company recently told American pilots that the system would not alert pilots about any sensor disagreement until the aircraft is 400 feet above the ground.
It just keeps getting worse. The NYT story cited above buried the lede. Even those who paid for and had an AoA disagree that worked had one that didn’t work during takeoff.

As an engineer SLF I feel this is becoming almost unbelievable. I predict Boeing will be making VERY LARGE political campaign contributions over the next few years.

Edmund



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Old 6th May 2019, 01:39
  #4966 (permalink)  
 
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FCTM on unreliable airspeed

Originally Posted by User7861 View Post
Excuse me if this was already mentioned before, but I have to ask:

Nobody seems to be disturbed about the fact that the Unreliable Airspeed memory items include two performance settings only, and none of those are suitable for an initial climb after take off.
80% 10 degress pitch is the one with flaps extended and gear up. Starting actions at 400 AGL would mean that somewhere around 1000' these values would be set if I happened to follow the memory items without thinking.
So then what? What about high terrain and MSA?
Why is there no initial thrust and pitch setting for take off?
My personal game plan would be to keep the take off thrust and an initial pitch somewhere 14-16 degrees up until MSA or in case of VMC to an altitude where I'm absolutely sure that there will be no terrain threat, then set the 80% 10 deg.
Can anybody here show me what am I missing? Is there any of you here, who would consider setting that pitch and power right after take off? Is there even any data about the actual climb rate at MTOW for that setting?
A legitimate question that I have been asking myself as well. Adding to what other posters have said, you can find answers in the 737 flight crew training manual:

“Memory items for target pitch and thrust must be accomplished as soon as it is suspected that airspeed indications are incorrect. The intent of having memorized pitch and thrust settings is to quickly put the airplane in a safe regime until the Airspeed Unreliable checklist can be referenced. The memorized settings are calculated to work for all model/engine combinations, at all weights and at all altitudes. The flaps extended settings will be sufficient such that the actual airspeed remains above stick shaker and below the flap placard limit. The flaps extended pitch and thrust settings will result in a climb."

Accordingly setting 10° pitch and 80% N1 will result in a climb at all weights. If you have a look at the departure chart that ET 302 flew you will see that terrain was not a factor for them for at least 40NM if they continue on runway heading. Also they had good visibility. Therefore setting these values would not have been a problem. However as you said, it is also an option to keep the TO thrust setting a bit longer and the pitch atitude at 15° in order to climb quicker to an altitude where you feel more comfortable. Nonetheless you have no guarantee from Boeing then that you will not reach flap placard speed at some point. If terrain is actually a factor that is a risk I would be willing to take and as 737driver said, the best option then would be to fly your company's engine out procedure.
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Old 6th May 2019, 01:48
  #4967 (permalink)  
 
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Originally Posted by 737mgm View Post
A legitimate question that I have been asking myself as well. Adding to what other posters have said, you can find answers in the 737 flight crew training manual:

“Memory items for target pitch and thrust must be accomplished as soon as it is suspected that airspeed indications are incorrect. The intent of having memorized pitch and thrust settings is to quickly put the airplane in a safe regime until the Airspeed Unreliable checklist can be referenced. The memorized settings are calculated to work for all model/engine combinations, at all weights and at all altitudes. The flaps extended settings will be sufficient such that the actual airspeed remains above stick shaker and below the flap placard limit. The flaps extended pitch and thrust settings will result in a climb."
Unfortunately, our company manuals don't go into that level of detail. It does have this little gem, though: "If the flight crew is aware of the problem, flight without the benefit of valid airspeed information can be safely conducted and should present little difficulty." Just a walk through the park.

I'm hoping this verbiage gets yanked with the next change.
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Old 6th May 2019, 02:53
  #4968 (permalink)  
 
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Boeing left airlines, authorities in dark on alert linked to 737 MAX crashes

https://www.smh.com.au/business/comp...06-p51kcy.html

Boeing knew months before a deadly 737 Max crash that a cockpit alert wasn't working the way the company had told buyers of the single-aisle jetliner.

Questions have been raised about the company's lack of transparency.

But the planemaker didn't share its findings with airlines or the Federal Aviation Administration until after a Lion Air plane went down off the coast of Indonesia in October, according to a Boeing statement Sunday. The accident occurred after erroneous readings by a single angle-of-attack sensor triggered software that pushed the jet's nose down until pilots lost control.

Boeing's latest disclosure raises new questions about the 737 Max's development and testing - and the company's lack of transparency. The alert was supposed to flash when two angle-of-attack vanes sent conflicting data about the relation of the plane's nose to the oncoming air stream. Boeing had told airlines and pilots that the so-called AOA disagree warning was standard across the Max fleet, as on a previous generation of 737 jets.

The software delivered to Boeing linked the signal with a second cockpit gauge - available for a fee -that displayed the readings from the two vanes. As a result, the AOA disagree light, which warned pilots of issues with the sensors, functioned only for customers that purchased the optional indicator.

"The question I have is just like we asked them in Reno, 'Is that all there is?' That's the biggest question," said Jon Weaks, head of the Southwest Airlines Pilots Association, referring to a meeting union leaders had with Boeing after the Lion Air crash. "It's obviously troubling that here is something else Boeing didn't get to us."

FAA criticism

The inactive alert was later deemed to be "low risk" by the FAA's Corrective Action Review Board, the regulator said Sunday. "However, Boeing's timely or earlier communication with the operators would have helped to reduce or eliminate possible confusion," the FAA said.

Boeing engineers discovered the discrepancy "within several months" of the initial Max deliveries in May 2017, the company said as it provided additional details of an issue that first came to light last week. The disclosures followed criticism from airlines and crash victims' relatives that Boeing hasn't been forthcoming about issues with the 737 Max, which has been grounded since a second crash in March, in Ethiopia.

The two disasters killed 346 people.

The manufacturer's own experts reviewed the issue and "determined that the absence of the AOA Disagree alert did not adversely impact airplane safety or operation," according to the Boeing statement. The company's review board decided the setup was acceptable until the two alerts could be unlinked with the next planned software update for the plane's display system.

Airline discussions

Rockwell Collins, which was acquired last year by United Technologies Corp., provides the cockpit displays and flight-control computers for the 737 Max. Another United Technologies division makes the angle-of-attack vanes for the plane.

United Technologies referred questions to Boeing.

The Chicago-based planemaker said its senior leadership wasn't involved in the review and first became aware of the issue after the Lion Air accident. Boeing also broke the news of the glitch to Max operators such as Southwest Airlines Co. in the aftermath of the initial crash.

"Why weren't the manuals changed? Until after Lion Air, our manuals said that worked," Weaks said. "You can't blame Southwest because that's the information they had from Boeing. We don't know what we don't know."

Boeing said it also told the FAA that company engineers had identified the issue in 2017, along with the findings from their internal review process. In December, a safety review board convened by the manufacturer confirmed that the absence of a functional AOA disagree light didn't present a safety issue.

Software update

Boeing briefed the FAA's Seattle aircraft certification office in November, and the information was forwarded to the agency's Corrective Action Review Board for evaluation, an FAA representative said Sunday. The panel determined the issue to be "low risk," and said Boeing would have to fix it as part of an overall package of enhancements to the Max in response to the Lion Air accident.

Before the Max returns to service, Boeing plans to issue a software update that will allow the AOA disagree light to operate as a standalone feature.

Boeing has separately been working to finalise a redesign of the software, known as MCAS, that was mistakenly triggered by the faulty sensor readings. The last major milestone is an FAA certification flight that the company expects to conduct shortly.
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Old 6th May 2019, 03:12
  #4969 (permalink)  
 
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Reference deactivated "AOA Disagree" alert.

Sloppy, sloppy, sloppy.

That being said, I think it is fair to say that prior to the MAX accidents, most of the pilots at my airline had no clue that there was such a thing as an "AOA Disagree" alert. I'm not sure it would have made any difference.
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Old 6th May 2019, 03:18
  #4970 (permalink)  
 
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Importance of the AoA disagree message

As an experienced 737 pilot I am little bemused at the suggestion that an AoA disagree message would decisively help things one way or the other. Faced with a stick shaker on take-off you are either stalled or you are not. It takes about three seconds to assure yourself that you are not, thus the sensed AoA is in disagreement with reality. AoA disagree? Check!

While I agree with the thrust of 737 Driver's argument, I am also aware that human perceptions and reactions are a lot more complex than we wish them to be. Crew performance can vary across a broader spectrum than we assure ourselves is the case.

I have watched pilot experience levels and basic skill sets decline over the years. The industry would be in crisis if demonstration of old fashioned handling skill sets were suddenly required to be paid more than lip service.

With regard to Boeing: I wonder how they will keep their ODE status, and I wonder if the FAA will be required, under this administration, to return to a more hands-on oversight role.

I would expect other regulators, if not the FAA, to require Boeing to address those other system concerns flagged by the whistleblowers prior to the Max flying again.
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Old 6th May 2019, 03:26
  #4971 (permalink)  
fdr
 
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737D;

your posts indicate that the crew of the flights were less than competent in essence, however, you also suggest that the training standards are deficient. One specific on competency is your statement that you would respond in the event that these crews encountered by recognising the problem, identifying the cause and completing the action within "5 seconds".

Okay.

You are currently a participant in an internet multi player demonstration of Schrödinger's cat gedankenexperiment, WRT observer impact on outcomes. You have knowledge that did not exist at the time of the events, and you have time to contemplate navels and determine a course of action, and by those factors alone, you are not able to replicate the conditions existant for the crews concerned. To judge the crews timeliness or lack of understanding is fundamentally flawed scientifically if you have any intent to understand what happened in these cases. Today, possibly the crews will respond effectively to this particular problem, but given the application of sods' law, someone on some dark night is going to brilliantly apply all the prompt response that will be gained from the establishment of the corporate knowledge of MCAS, and they are going to misapply it as a slip in SA will have occurred. That is the insidious nature of the world we live in, where unintended consequences are a real outcome.

On "5 seconds", that is of course 60% longer than the out of trim case that the aircraft is certified for, so presumably your "5 Seconds" is also potentially inadequate, however I assume that you would not consider your "5 Second" response time to be incompetent?

The Boeing OEB raised after the first accident is pretty darn silent on the fact that the aircraft can enter a condition where the airloads on the stab can exceed the crews ability to effect a recovery. For that gem, you have to read the FCTM and comprehend what the weasel words there mean in the real world, that in order to recover in the severe out of trim case, you may have to let the aircraft recover towards it's trim state sufficiently to unload the stab so that the trim can be actuated. That sounds all well and good if you are not confronted with planet earth in the upper windscreen at close proximity to achieve that condition. That is pretty much an existential threat to the crew, and I would hazard that they were indeed under some stress, that you as an observer from the sideline have not had to experience when making your "5 Second" judgement on competency.

I agree that training needs to be lifted around the industry, we dont necessarily need more training, we need training that is not wasteful fo the resources that exist, as they are to day. We are currently governed by the aviation industries own version of political correctness, A.K.A. as SMS, and QA. In order to give a simplified box ticking exercise to regulators and managers, we come up with matrices and checklists that are fantastic for showing compliance, but, that is all. There is no closure of the loop on the fact that the crew may comply with a procedure or policy that in itself increases operational risk, or is impossible to do as it conflicts with the real world. The other sort of failure (think false negatives, false positives) arise when the boxes get ticked, but the impact of implementation is not observed. Our roles, policies and procedures are developed usually as bandaids on top of bandaids to reduce the risks of something, either real risk, or showing compliance (another form of risk - commercial). In all cases, however it is unlikely that the 200 hr pilot sitting in the RHS seat of the plane was the cause of the competency issues, he/she cannot be other than the logical outcome of what the industry has accepted as a good solution to unfettered growth (a cancer in effect, sounds good until the consequences start being felt).

Sully gets mentions in the conversations. The NTSB acknowledged the human in the loop issues in the response time during the public hearings and that was factored into the analysis. I would suggest that the recognition aspects of a loss of all engines event while unpleasant, is simpler than the multiple failure cues that existed on the Lion Air and Ethiopian aircraft. Rather than acknowledge the human in the loop, you have indicated that "5 Seconds" is a competent response time. I would counter that the time you suggest is arbitrary and unreasonable, and does not reflect competency, it merely reflects the opportunity you have had to consider your hypothetical response to the scenario post hoc.

As an aside, long long ago etc... I was evaluating a checker and a trainer in a sim, while they collectively beat up on a student (a B7xx line captain). They were remarkably derisive of the pilots competency. At the end of the session, I asked these aces to hop in the seats and I was going to give them a single failure well within the realms of likelihood. With a modest cross wind, as the wheels left the ground, I failed the worst case engine, from the standpoint of applied rudder at that time, I declined to use crash override to make the point. On leaving the sim session, both checker and trainer apologised to the student for their lack of respect in their comments. Point is this, humans in the loop are a fact, and it is important to recognise and respect that. Sully made a difference to the outcome, as more often than not occurs every single day in countless anomalies that the industry encounters. Humans are the strength of the system while being a point of failure, and that needs to be accepted.

Over the years, I have listened to too many CVR's and looked at too many FDR/QAR outputs to expect that any crew will achieve much in 5 seconds on a normal flight, other than pavlovian responses for failures on a TO. The highly trained response on an RTO etc is however as often as not carried out incorrectly, so I wonder if the 5 Seconds is not just a bit harsh as a standard.

A final thought: The crews encountered an unusual trim case, the checklist is for a runaway trim, yet the problem did not actually present as such, there was a trim error that occurred, but the trim responded normally to the crews trim inputs, and then after a period of time was anomalous again. That is not a simple set of facts to decipher in short order. Given their time over, I expect that the crew would follow your advice and act within 5 seconds and cure the ills of the world.

kind regards,

FDR
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Old 6th May 2019, 03:29
  #4972 (permalink)  
 
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Originally Posted by RickNRoll View Post
Turning off the magic is what activates MCAS when the AoA is faulty.
Do you make a habit of flying of turning on the autopilot when the stick shaker activates after takeoff?
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Old 6th May 2019, 03:38
  #4973 (permalink)  
 
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Originally Posted by wonkazoo View Post
From the Seattle Times Article:

"Four additional concerns specific to the 737 MAX were listed in the 2017 report. All were related to certification of legacy systems inherited from the earliest 737 models that were found by FAA technical staff to be noncompliant with the latest safety regulations.

These involved a lack of redundancy in the rudder cables; a too-high surface temperature allowed in the fuel tank; insufficient fireproofing around the plane’s auxiliary power unit in the tail; and using high-power wiring to connect to a switch inside the fuel tank.

All these issues were flagged by safety engineers working at the FAA as requiring fixes before the MAX could be certified.

The MAX won certification anyway after managers on the Boeing side of certification insisted that these were non-issues and managers on the FAA side agreed to let it move ahead with these shortcomings unaddressed."

I'm sorry, I'm trying to pick my jaw up off the floor. The 737 has no redundancy in it's rudder control system?? I've had a rudder cable failure- trust me when I say it can end very badly!! Can any (ahem) 737 Driver confirm that this is in fact accurate, that there is either no or a lack of redundancy in the 737's rudder??

If that is true that is the most shocking thing I have read about aviation in a very long time- and that the airplane was granted its STC just three years ago makes this even more shocking.

If it is true.

Cheers-
dce
The 737NG and Max have a single set of rudder cables running from the forward quadrants to the aft quadrant.
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Old 6th May 2019, 04:04
  #4974 (permalink)  
568
 
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Originally Posted by edmundronald View Post


It just keeps getting worse. The NYT story cited above buried the lede. Even those who paid for and had an AoA disagree that worked had one that didn’t work during takeoff.

As an engineer SLF I feel this is becoming almost unbelievable. I predict Boeing will be making VERY LARGE political campaign contributions over the next few years.

Edmund



Regarding the "political contributions",depends how much money is left in the pot after litigation.
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Old 6th May 2019, 04:21
  #4975 (permalink)  
 
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Originally Posted by Dave Therhino View Post
The 737NG and Max have a single set of rudder cables running from the forward quadrants to the aft quadrant.
You must be $hiting me...

Single set meaning one set for left seat and one set for right?? (Which is still a bit shaky if you think about it) If there are two sets are they in close proximity at any point??

Any drawings, diagrams or photos??

Thx-
dce
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Old 6th May 2019, 04:38
  #4976 (permalink)  
 
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On the subject of training, what I find quite unbelievable is that every airline seems to have their own training procedures for a specific aircraft... Shouldn't there be just standard training dictated by the manufacturer of the aircraft and that should cover everything required.. there should be no need for carrier specific training other than perhaps some company policies, but nothing related to operating the equipment.
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Old 6th May 2019, 04:57
  #4977 (permalink)  
 
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Originally Posted by OldnGrounded View Post
From today's NYT:
Boeing Believed a 737 Max Warning Light Was Standard. It Wasn’t.

AOA disagree, of course. Sheesh.
Thanks for the link. It gets worse:
When Boeing explained to pilots in one meeting how systems on the Max worked, the company said that the disagree alert would function on the ground. In the late November meeting, Boeing told pilots for American Airlines (which had bought the add-on) that their disagree alert would have notified them of problems before takeoff.

“We were told that if the A.O.A. vane, like on Lion Air, was in a massive difference, we would receive an alert on the ground and therefore not even take off,” said Dennis Tajer, a spokesman for the union representing American Airlines pilots. “That gave us additional confidence in continuing to fly that aircraft.”

But in the last several weeks, Boeing has been saying something different. Mr. Tajer said the company recently told American pilots that the system would not alert pilots about any sensor disagreement until the aircraft is 400 feet above the ground.
My emphasis added. This is a critical point that was touched on previously. It is impossible to get a reliable AOA value until there is significant forward airspeed. Plus it takes time to compare the two values, and trigger the AOA disagree warning. By then the aircraft is airborne. Its a bit too late. If it was fitted and worked, which it didn't.
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Old 6th May 2019, 05:12
  #4978 (permalink)  
 
Join Date: Feb 2019
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Boeing just issued a statement on their website:

Boeing Statement on AOA Disagree Alert

Plus it takes time to compare the two values, and trigger the AOA disagree warning.
Getting confused here. Isnt it reported that MCAS only uses one AoA vane? If there is a disagreement, what does it matter if it relied on one? Add-on alert or not, didnt MCAS only use one?

Last edited by Smythe; 6th May 2019 at 05:31.
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Old 6th May 2019, 05:28
  #4979 (permalink)  
 
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Originally Posted by Smythe View Post
Boeing just issued a statement on their website:

Boeing Statement on AOA Disagree Alert
What a house of cards.

If you read the statement it goes to great lengths to show how they determined over and over again that the AOA disagree alert does not impact flight safety. Which, if there wasn't an autonomous flight control system that has full authority over the horizontal stabilizer based solely on the output of a single AOA vane, might actually be true.

Left unaddressed by the Boeing statement is that their determination is only operative until you have a previously unknown system that utilizes a single AOA input and can trim the horizontal stab down at 2.5 degree intervals all the way to the stops. Until the airplane is in an unrecoverable state should the crew not react quickly and accurately enough.

Oops!! We forgot about that one!!

I've got ten bucks that says Boeing ends up in bankruptcy to protect them from the various and numerous liabilities they are now facing. (Orders that won't be filled, dead people, lost revenues by airlines already in possession of the airframes, future liabilities, etc...)

I've got another tenner to donate if the MAX is flying again before the end of the year, and one more for it never flying again in passenger service.

That's my gambling quotient for this year- I hope it pays well!!

Regards,
dce
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Old 6th May 2019, 05:50
  #4980 (permalink)  
 
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Originally Posted by Smythe View Post
Boeing just issued a statement on their website:

Boeing Statement on AOA Disagree Alert



Getting confused here. Isnt it reported that MCAS only uses one AoA vane? If there is a disagreement, what does it matter if it relied on one? Add-on alert or not, didnt MCAS only use one?
Lion air flight had an AOA disagree of from memory of 40 degrees on the ground and in flight. So with this disagree warning the flight would not have happened - the fact the LH AoA was in error that would have activated MCAS then becomes irrelevant - the flight would not have happened.

NOTE - my understanding is that the LH aoa on Lion Air read 40 degrees different to the RH AoA in every position stationary or moving.
Bend alot is offline  

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