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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 20th Mar 2019, 20:47
  #2181 (permalink)  
 
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Originally Posted by derjodel View Post


Doesn’t Boeing basically admit negligence and responsibility for the crash with the original design?

The whole “it was safe but now it’s safer” spin is like mcdonalds lowering the temperature of coffee “just to make it even safer and more full bodied now”. Remember, mcdonalds had to pay 2.7M just for burns - to a single person.
CNBC is reporting...The FBI is reportedly aiding criminal investigation into Boeing 737 Max certification


Last edited by Piper J3; 21st Mar 2019 at 01:13.
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Old 20th Mar 2019, 20:48
  #2182 (permalink)  
 
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Originally Posted by yellowtriumph View Post
Boeing's mission is the same as any other publicly listed company - to maximise profits for the shareholders and to act in their best interests. To do otherwise would probably be a dereliction of the directors legal responsibilities. It does this by designing and manufacturing equipment to the highest standards but that is not its mission, it's the means to the end. I do not mean to denigrate Boeing's equipment and staff and all their efforts which I personally admire hugely. But it's the truth.
The statutory duties of directors are not what you state as a 'mission' and maximise profits.
The board of any public company, is in the statute, required to act in good faith and the best interest of the company.
Pursuit of profit is not necessarily in the long term interests of the company owners.
For management may pursue all sorts of profit maximising activity which could include simply sell off all the assets. This may maximise 'profit' in the short term, but may damage the company and the interests of the owners, both current and future.
The role of the board is governance. That is how it is framed in the statute in the United states, the UK and the antipodes.
Directors have at their disposal both internal and external resources and are as demonstrated by case law, required to satisfy themselves by conducting any investigation into a matter they deem appropriate.

Eye pleasing stock prices satisfy management, and you can bet the CEO of Boeing's statement have careful consideration of share market impact. After all personal remuneration is at stake.
Weasel word statements carefully vetted by in-house legal and PR contain nothing admissible, no admission of fault, wrong doing or responsibility.
They are as lightweight as the paper on which they are written.

The directors of Boeing will be looking closely at any personal exposure.

Were one to look at the statute in Germany, directors are far more accountable for impact on among other things customers.
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Old 20th Mar 2019, 20:52
  #2183 (permalink)  
 
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GPS is irrelevant to this thread.

GPS position is irrelevant to this thread. Even if the speed of the aircraft relative to the Earth was relevant, the 737 does not use GPS to display ground speed. It uses the calculated FMC position, which is derived from the IRS position, the triangulated DME position, and the GPS position via a complex formula. At times, the GPS input to the FMC may be ignored altogether. And in fact, GPS is not even required for non-EDTO (Extended over water) 737 operations.
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Old 20th Mar 2019, 21:07
  #2184 (permalink)  
 
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Originally Posted by StuntPilot View Post
My thoughts about MCAS as a hardware designer:

1. Aircraft are nonlinear/unstable systems that can only be stabilized by control laws in a small (linear perturbations) part of the parameter space. A deep stall is an example of non-linearity.

2. Complexity explodes exponentially with state (autopilot mode, AOA vane failure detected etc.), an important design goal is to reduce state. State includes any if... then... in software.
When software initiates a state change on its own (autopilot switches off, systems disabled because of a broken sensor, stall recovery deployed) this should be announced to the pilot by aural warning. A pilot should always know exactly what the control state of the aircraft is, 'what is it doing now?' is not a good thing to wonder about up in the air.

3. There is unavoidable state that relates to the physics of flying: flaps, trim, gear = configuration. If automation is allowed to mess with configuration there must be cutouts and self-checks (cross checks against other sensors, stick position, whether data is consistent) to prevent instability.

4. MCAS has a very specific control function in a specific part of the flight envelope. It is easy to cross check with other sensors whether this part of the flight envelope is entered and how large a control input is required.

It puzzles me that, at complete odds with this, MCAS was given an integrating control function without bounds on a crucial flight control surface. Without data validity check. Without aural deployment warning. Without aural and visual AoA disagree warning. Without control input cross check. Without ADIRU cross check.

With safety critical subsystems there should always be at least 2 barriers before handing things over to a human as the last line of defense to prevent an incident.
The above quoted post got no reaction, as it unfortunately appeared in between a series of tit for tat posts. Succinctly written, it describes the background to this problem in what appears to be a completely valid manner.

Therein lies the problem, as Boeing have hung MCAS on the tail of the STS, which has for many years operated quietly in the background to effectively neutralize long period elevator demand, and thereby providing the full range of elevator control when required on demand. Its the extra lift generated by the engine nacelles, now further forward and higher than those on the NG, that needed to be neutralized to maintain the correct feedback forces on the control column in high AoA situations.

As described by StuntPilot, MCAS is a reconfiguration sub-system relying on non validated air data, and steps across the safety critical barrier in an insidious way.
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Old 20th Mar 2019, 21:12
  #2185 (permalink)  
 
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Amazing the stabilizer could be driven to end stop with no audible warning or cross check
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Old 20th Mar 2019, 21:14
  #2186 (permalink)  

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Maybe. Maybe he was one of the Yeager, Doolittle or Lindbergh clones we have here or like Luke?
You don’t have to be Chuch Yeager or the ace of the base to operate the Stab Trim Cutout switches if the stab is starting to run away in increments or continuously.
Been doing it in various Boeing simulators for 30 years and once in real life, pretty basic stuff, really..
We still don’t know what happened in Etiophia, it has been quiet after they got the FDR and CVR readouts. Could have been a bunch of things other than faulty AoA or MCAS.
If it was a runaway stab however, you don’t have to be Chuck Yeager to stop it cold.
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Old 20th Mar 2019, 21:38
  #2187 (permalink)  
 
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Originally Posted by Rated De View Post
The statutory duties of directors are not what you state as a 'mission' and maximise profits.
The board of any public company, is in the statute, required to act in good faith and the best interest of the company.
Pursuit of profit is not necessarily in the long term interests of the company owners.
For management may pursue all sorts of profit maximising activity which could include simply sell off all the assets. This may maximise 'profit' in the short term, but may damage the company and the interests of the owners, both current and future.
The role of the board is governance. That is how it is framed in the statute in the United states, the UK and the antipodes.
Directors have at their disposal both internal and external resources and are as demonstrated by case law, required to satisfy themselves by conducting any investigation into a matter they deem appropriate.

Eye pleasing stock prices satisfy management, and you can bet the CEO of Boeing's statement have careful consideration of share market impact. After all personal remuneration is at stake.
Weasel word statements carefully vetted by in-house legal and PR contain nothing admissible, no admission of fault, wrong doing or responsibility.
They are as lightweight as the paper on which they are written.

The directors of Boeing will be looking closely at any personal exposure.

Were one to look at the statute in Germany, directors are far more accountable for impact on among other things customers.
Olezcek & Rated De. Yes, perhaps I should have said ‘maximise shareholder value’ rather the shareholder profits. I quote from this site - which relates to the UK only.

https://www.franciswilksandjones.co....uciary_duties/

“Directors of any company in the UK are separate from the business owners, who are the Shareholders, and have a duty to manage the company (or companies), over which they are appointed, solely in the interest of Shareholders.”

I don’t think we are too much at odds with one another on this.



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Old 20th Mar 2019, 21:44
  #2188 (permalink)  
 
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The bigger picture here is the (lack of) training. Training is perceived as expensive by operators, to be minimised by the accountants and finance types. The reason we have the MAX and not the 7x7 narrowbody is because of (non)-training. Training has progressively been hacked back to the absolute bare minimum to pass the course. There are less and less descriptions in the manual of systems operations, limitations have been reduced to the colour coding on the instruments. In short, commercial pressures (perceived or real) have reduced pilots to mere SOP system operators. From the accountants perspective, all problems have been solved by the aircraft manufactures, and grudging concede we just need the absolute lowest level carbon based AI automons to read the checklist and follow SOP, to the letter if something goes wrong.

To accountants, flying aeroplanes is a "settled science", and therefore training and employment conditions are the subject to round after round of continuous cuts and we still have a "NEW" 1967 aircraft rolling off the production line with all the human factor issues baked in from another era extending well into the future. They have failed to accept the QRH introduction that states the assumption behind the checklist is that only one thing will go wrong at a time, and do not consider multiple failures.

AF447, Air Asia 8501 TransAsia Airways Flight 235 as well as a string of Adam Air incidents & accidents all have their genesis in the minimum training philosophy. Unfortunately, the trend is likely to continue until the industry wakes up to the fact that cutting training to the bone is NOT a competitive advantage.
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Old 20th Mar 2019, 21:52
  #2189 (permalink)  
 
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Martin.
Gordon speaks a lot of sense and has it right and well balanced.
Yanrair
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Old 20th Mar 2019, 21:58
  #2190 (permalink)  
 
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Originally Posted by Kerosene View Post
Suppose MCAS becomes unavailable during flight e.g. due to Stab trim deactivation. The MAX’s flight characteristics in approach to stall scenarios proved not certifiable without MCAS as a fix. I’d like to ask the ones in the know (FcEng and others) how critical the loss of MCAS in flight would be in real life. For example, encountering a flight upset with approach to stall, how easily can this be recovered without MCAS? How was the risk of such an event assessed? Was it demonstrated in test flights? Why was it determined there would be no need to train flight crews on the simulator for the changed handling outside the certification parameters?

In a previous post I assumed such a scenario to be critcal, but perhaps it isn’t? Thanking you in advance for shedding light on this issue.
Good question. I fear there will be no answer until there is another crash due to this configuration (stab trim switched off)

Not only MCAS would be missing, also STS and electric trim, everything would have to be done manually by the trim wheel and a good amount of sweat...

Last edited by deltafox44; 20th Mar 2019 at 22:52. Reason: clarity
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Old 20th Mar 2019, 22:26
  #2191 (permalink)  
 
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Originally Posted by jagema View Post
Likewise, when I read their statement, "to make a safe airplane safer" I also raised the eyebrow.
Evidently FAA and Boeing both agreed these were required changes to MCAS logic from what they could learn from LionAir. Why the type was not grounded then and instead they let the fleet fly while developing the fix which is now being required to have them airworthy again is very questionable...
+1
"to make a safe airplane safer" is just a Coué-method equivalent of "to make a dangerous airplane a little less dangerous"
Or an aeronautical equivalent of washing powder advertisement "to wash whiter than white". If it's whiter now, it was not white before, it was grey
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Old 20th Mar 2019, 22:29
  #2192 (permalink)  
 
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Originally Posted by FCeng84 View Post
VicMel - I really appreciate your thoughtful response. I sense that overall you and I are on the same page. Please allow me to provide a few inputs on your points:

A i) The update in work by Boeing is in response to the Lion Air accident, not the Ethiopian accident. Hopefully we will know more about the Ethiopian accident soon and only then will it be possible to determine if this same update would have helped lead to a better outcome in Ethiopia.
A ii) It seems that the proposed update will disable MCAS if the two AOA vanes do not track each other sufficiently. The severity of the degradation in handling qualities without MCAS must be minor enough to allow for this reduction in MCAS availability. Boeing must be assuming some probability for an AOA sensor failure and then showing that it is acceptable to turn MCAS off twice as often as a failure of either AOA sensor would lead to MCAS shut down.
A iii) No MCAS when AOA vanes do not track. See A ii above.
A iv) I doubt that we will find that the MCAS update reduces the size of a single increment of MCAS stabilizer motion. I can't imagine that Boeing would have given this function any more authority than absolutely needed to meet FARs and thus there is probably no room to reduce its single increment authority.
C) MCAS is implemented within the FCC within the same software that controls other automatic stabilizer control functions such as offload when A/P is engaged and STS. This code already required to be designed to high standards.
Conclusion a) We may need to rely less on critical crew action, but there must be some base level that can be counted upon. I suggest at least:
- RTO for engine out below V1
- Pull for takeoff somewhere near Vr
- Gear and flap management and coordination with associated speeds throughout flight
- Comply with ATC guidance
- Ability to navigate to destination
- Ability to capture and follow glideslope and localizer to runway and command landing flare
- Recognize unstable approach and execute go-around
- Sorry for the length of this list. My point is that there are many pilot actions we count on to maintain safe operation
Conclusion b) I fully agree and suggest adding that if the inputs are garbage the system should be robust enough to maintain safety.
I just want to thank you for your valuable contribution to this topic. You are the person here who have given by far the most amount of factual information regarding the exact functionality of the MCAS system and how this system was developed.
Thanks!
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Old 20th Mar 2019, 22:30
  #2193 (permalink)  
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https://www.reuters.com/article/us-e...-idUSKCN1R11AK

March 20, 2019 / 4:39 AM / Updated 7 minutes ago

Boeing, FAA officials called to testify in U.S. Senate on 737 MAX plane crashes

Maggie Fick, Cindy Silviana, David Shepardson
ADDIS ABABA/JAKARTA/WASHINGTON (Reuters)

Boeing Co faced growing pressure in Washington on Wednesday with U.S. lawmakers calling for executives to testify about two crashed 737 MAX jets even as the world’s biggest planemaker works to overcome obstacles to returning the grounded fleet to the skies.
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Old 20th Mar 2019, 22:32
  #2194 (permalink)  
 
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deltafox44, #2203
The 737 Max testing would have encountered and evaluated the deficient condition - how else would the shortfall be recorded. Perhaps not so for the abnormal drills.

An inflight failure of MCAS, in addition to being detected and managed, should not create any significant hazard as the critical flight region is at or beyond the limit of a normal flight envelope. Although I would be concerned about a GA, depending on the level of the initial, reduced thrust setting.
The safety case for using manual trim has been made in considering current failure conditions; thus MCAS unavailability should not be more frequent than those, but a ‘fix’ might not even result in the loss off trim for a system failure.

Curtain Twitcher # 2201,
Your concerns over training should be revised by reconsidering the situation if the existing system were to have been described, with the use of the ’post hoc’ abnormal drill.

MCAS training might have been a cursory acknowledgement of the system and that its operation will not intrude on normal flight conditions. The abnormal procedure ticked off by the existing runaway trim drill and continued flight without trim. Discussion of inadequacy might only arise after ‘the first incident’.

In this my concern, even with a ‘fix’, would be more about the assumptions for runaway trim, pilot identification, the crews’ ability to manage the stick forces, and to physically move the trim wheel.





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Old 20th Mar 2019, 22:40
  #2195 (permalink)  
 
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Originally Posted by yanrair View Post
Martin.
Gordon speaks a lot of sense and has it right and well balanced.
Yanrair
Yes, but Mr Bethune was very much part of a different Boeing.
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Old 20th Mar 2019, 22:51
  #2196 (permalink)  
 
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Originally Posted by yanrair View Post
Gums says 'cutting accident crew some slack". So does everyone I think. If they made an error and we have no idea if they did, it would not be their fault but poor training. I have never met or heard of a pilot who sets out to do a bad job or kill himself. Other than the Pyrenees incident of co
course.
There seems to be a bit of a muddle about AoA sensors and Airpspeed disagree. They are not necessarily connected in any way.

AoA detects a stall by measuring the angle of attack with two sensors, one each side. Measuring the angle of airflow.
Speed is measured by sensing air pressure in a tube facing forwards (pitot)and converting that into Indicated Airpspeed. Not the same as real speed.
GPS measures real speed and is almost never wrong.
Say you have blocked pitot tubes as per aF 447, the AoA still works and stall warning still works.
Say you have frozen AoA vanes so that they are not able to detect stall, or incorrectly detect a stall (as is suggested in these Max incidents) then the Airspeed should still work.
Another scenario is that one airspeed is faulty, but the other two work - there are three airspeed indicators. That one is easy since you go for the two that agree. Backed up with GPS.
And in all these cases GPS will still work.
So the changes of losing AoA information AND Airspeed information at the same time are pretty remote.
This is just for information since there seems to be a misunderstanding about the functions of the various systems here.
There is one last way of determining speed. Pitch and power. 6 degrees of pitch and 60% N1 power will fly straight and level and at a safe speed NO MATTER WHAT ANY OF THESE OTHER SYSTEMS ARE SAYING. [True for lower levels]
The point is I suppose that this is a very complicated area but we can also overcomplicate it.
Yanrair
Actually, before you go any further, Lion Air [and Ethiopian Air, and indeed Southwest as late as last November 2019], do not have AOA disagree indicator installed in their planes. So, they can absolutely see something was wrong but NOT TO EXTENT OF AOA DISAGREEMENT/MALFUNCTION. However, they can absolutely see the indirect/direct effect of AOA disagreement: false stall warning and, unfortunately at the time, the still mysterious, ghostly, undocumented and deadly MCAS which thought to be the trim done by "STS going the wrong direction due to speed difference", as the pilot had written it on their report about the incident in the previous sector, started their discrete 2.5-degree-every-10-second and absolutely unlimited trimming due to a faulty logic loop.

The main reason why the previous pilot failed to write the stick shaker and cutting off the stab trim, probably because:
1. They thought the nose down trim was simply STS malfunctioning and trimming the other way due to air speed difference [i.e. IAS disagreement].
2. They are convinced that all the plane's problems came from whatever causing the IAS disagreement and unreliable ALT.

Little that they know had the stick shaker and stab trim cut-off incident/action were also being written, we'd end up having a different conversation right now [AND perhaps the MCAS thingy would've been remained hidden...].

In other words, we can just throw off all the discussion about malfunctioned AOA vanes or AOA disagreement stuff when we are trying to imagine about the "why and the what" of the Lion Air's pilot action, because they didn't have any means to consider that possibility.

Last edited by patplan; 20th Mar 2019 at 23:02. Reason: clarity...
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Old 20th Mar 2019, 22:53
  #2197 (permalink)  
 
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Originally Posted by yanrair View Post
........737 had a secret weapon- airstairs! ..............
So secret that they never let anyone see them.
In many years of getting on and off 737s I have never, to my recollection, done so by way of said air-stairs.

It's like saying Tupolevs have an advantage cause their undercarriage allows them to land in a cow paddock.
Might be useful in time of war but seldom see 'em out grazing with the herd.
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Old 20th Mar 2019, 23:02
  #2198 (permalink)  
 
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Originally Posted by WingNut60 View Post
So secret that they never let anyone see them.
In many years of getting on and off 737s I have never, to my recollection, done so by way of said air-stairs.
Let me help you out:


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Old 20th Mar 2019, 23:05
  #2199 (permalink)  
 
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Stumbling back in to deal with days of posts saying "well just look at other sensors!"

Sensor fusion is hard enough to do when you assume all your sensors are working correctly. When you add in "oh, and, toss out any sensors that you think are wrong" you end up in an unverifiable mess.

A rule of thumb is that any variable you add into the decision process introduces at least one (and usually far more than one) potential defect.

This is a poor candidate for Machine Leaning AI, because there are not enough good AND bad scenarios to train on.. so you have to fall back on algorithmic methods, and you pretty much can't short-cut that.. which means a lot of development work and validation work. TANSTAAFL..

OK, I'll shuffle back to the gate now.

...tom
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Old 20th Mar 2019, 23:15
  #2200 (permalink)  
 
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Originally Posted by DaveReidUK View Post
Let me help you out:
I wasn't doubting their existence, Dave.
Just pointing out that for most operator's in these parts, if they can't get an air-bridge, are happy to make do with the push-up stairs with a little bit of protection against the sun and / or rain before you leap on the bus.

Not a concern for Ryanair, I guess.
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