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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 29th Apr 2019, 20:45
  #4601 (permalink)  
 
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Originally Posted by wonkazoo View Post

With those two statements on offer- and the acknowledgement that there is plenty of blame to go around, the question I have is why are you not focusing on Boeing, the corporate culture that created this monster, the profit-driven betrayal of everyone here, and the fact that they are clearly working to pull a rabbit out of the hat in lieu of actually starting over again- which is what any rational society would require them to do. Yes, we know who the four crew members are, so that makes them easy targets, but if the professionals on this forum are willing to eat their own while looking the other way as Boeing goes about its PR campaign then what does that really say about all of us??
Why indeed?

Let me answer a question with a question.

Are you more interesting in bitching or saving lives?

Sorry to put it so bluntly, but really that is what it comes down to. I've already answered this query, but let me state it again. There was a chain of causation in these accidents. That chain consisted of the following:

1. Lapses at Boeing
2. Lapses at the FAA and other certificate authorities
3. At least in the case of Lion Air, lapses in the maintenance/logistics area.
4. Lapses within the airlines in terms of education, training, policies, and culture​​​​​​.
5. Lapses in flight crew member actions

Granted, some may have a different list, but this mine for moment. Now let me ask very pointedly, if the goal is to increase the safety of our operations and prevent future accidents, which item on this list do we, as front line operators, have the most power to effect?

I don't care how insightful or detailed of analysis anyone on this forum could come up with on items 1 thru 3, the chance of it making any difference is essentially zero. It might make you feel better in some respects, but it will not change a thing. Maybe, if the right people are paying attention here, we could have an impact on item 4. However, if the motivation is truly to improve safety and save lives, item 5 is where we ought to spend our time.

As I've said several times already, you can't solve a problem until you recognize a problem exists. I'm sorry if in the course of defining the problem it appears that we are "eating our own," but that is not the intent.

BTW, doesn't it really bug you how Boeing, the FAA, and the airlines try to be all mushy-mouth in saying that they really didn't screw things up? Of course they did!

Why don't they just admit it and get on with fixing their problems?!

That is a very good question indeed.
.

Last edited by 737 Driver; 29th Apr 2019 at 22:27.
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Old 29th Apr 2019, 21:03
  #4602 (permalink)  
 
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Groucho Marx words come to mind: "Those are my principles. If you don't like them, I have others".
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Old 29th Apr 2019, 21:07
  #4603 (permalink)  
 
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Originally Posted by weemonkey View Post
Would some one detail these "lapses" at Lion air alongside supporting evidence..
You might want to compare

a) the FDR traces from the penultimate flight

b) what the crew wrote up about it (or, rather, didn't) in the tech log
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Old 29th Apr 2019, 21:21
  #4604 (permalink)  
 
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Originally Posted by weemonkey View Post
oh you mean form an opinion then...
Well yes, I would hope that having compared them, you would form an opinion.

You did ask, after all.
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Old 29th Apr 2019, 21:32
  #4605 (permalink)  
nyt
 
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The thing is, there would be no need to discuss any of this if it wasn't for these poorly-trained pilots flying one of the thousands of planes ordered. And SLFs decided (so far) that the ticket price covers the risk of flying with less reputable airlines (which again, is probably better for them than not flying at all to get where they want).
As was stated before by a safety engineer, you can address the current situation by more training for a lot of people (increasing costs hence tickets price), and only reducing the risk by a small margin (HF being what is is). Or you can fix the design at a lower cost for everyone (but Boeing), considering that the current average level of airmanship is sufficient. One could say that given the actual safety record of the industry, it is.
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Old 29th Apr 2019, 21:43
  #4606 (permalink)  
 
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Originally Posted by 737 Driver View Post
Why indeed?

Let me answer a question with a question.

Are you more interesting in bitching or saving lives?

Sorry to put it so bluntly, but really that is what it comes down to. I've already answered this query, but let me state it again. There was a chain of causation in these accidents. That chain consisted of the following:

1. Lapses at Boeing
2. Lapses at the FAA and other certificate authorities
3. At least in the case of Lion Air, lapses in the maintenance/logistics area.
4. Lapses within the airlines in terms of education, training, policies, and culture​​​​​​.
5. Lapses in flight crew member actions

Granted, some may have a different list, but this mine for moment. Now let me ask very pointedly, if the goal is to increase the safety of our operations and prevent future accidents, which item on this list do we, as front line operators, have the most power to effect?

I don't care how insightful or detailed of analysis anyone on this forum could come up with on items 1 thru 3, the chance of it making any difference is essentially zero. It might make you feel better in some respects, but it will not change a thing. Maybe, if the right people are paying attention here, we could have an impact on item 4. However, if the motivation is truly to improve safety and save lives, item 5 is where we ought to spend our time.

As I've said, you can't solve a problem until you recognize a problem exists. I'm sorry if in the course of defining the problem it appears that we are "eating our own," but that is not the intent.

BTW, doesn't it really bug you how Boeing, the FAA, and the airlines try to be all mushy-mouth in saying that they really didn't screw things up? Of course they did!

Why don't they just admit it and get on with fixing their problems?!

That is a very good question indeed.
.
My answer to the question would be that apportioning blame is a second order to actually determining the cause/reason the planes crashed. Isn't the one inescapable fact that had those planes been earlier models the dead would still be alive? You can argue that the pilots should/ ought to have been capable of handling the problem that they were faced with, but again in aviation as for cars technology trend towards increased safety. To me a lowly PAX maybe, but one who is still capable of analysing facts, nothing about the MCAS introduction says increased safety, rather a crude fix
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Old 29th Apr 2019, 22:01
  #4607 (permalink)  
 
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Originally Posted by nyt View Post
The thing is, there would be no need to discuss any of this if it wasn't for these poorly-trained pilots flying one of the thousands of planes ordered. And SLFs decided (so far) that the ticket price covers the risk of flying with less reputable airlines (which again, is probably better for them than not flying at all to get where they want).
As was stated before by a safety engineer, you can address the current situation by more training for a lot of people (increasing costs hence tickets price), and only reducing the risk by a small margin (HF being what is is). Or you can fix the design at a lower cost for everyone (but Boeing), considering that the current average level of airmanship is sufficient. One could say that given the actual safety record of the industry, it is.
I have an issue with increasing ticket price to cover for more training for a lot of people...the bean counters in few years will come with a way to reduce costs to increase profit, reducing the training costs.
The reputable airlines have "forced" Boeing to come up with the MAX, without SIM training in order to compete with AB. I found very difficult to accept that the issue of SIM training/MAX is driven by ticket prices, reputable airlines are probably enjoying bigger discounts on planes. Delta/American/United have reported multi billion dollars net profit in 2018. Spending 60 million of that profit would allow to purchase 2 SIM (5 million each), and perform 10000 hours of training on them (5000/hour). I do not think will break the companies, unless you are a bean counter, than we got to my first paragraph....
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Old 29th Apr 2019, 22:05
  #4608 (permalink)  
 
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One more try

Originally Posted by wonkazoo View Post
L39 Guy and 737 Driver- I owe you both a reply form last night, but it will have to wait for a bit.

In getting caught up with the thread just now a number of continuations of the theme from teh past week popped up, some in support of your stated observation/opinions and some against. Instead of arguing about them ad infinatum I had a vision of explaining how we aren't necessarily as far apart as it may seem, but also how your view as stated is (IMHO) deeply flawed and unforgiving towards four people who are not here to defend themselves.

My path to enlightenment is actually very easy and short.

Assumption: MCAS is a bastard system (some would say a killer) that was created and installed at the last minute and that provides a stupid feel/feedback control with actual control over the entirety of the horizontal stabilizer's range of movement.

Statement 1: Many professional pilots feel strongly that the primary focus for responsibility (note I said primary, not sole) lies with the airmanship (or lack thereof) of the flight crews who perished. In a narrow window of time they failed to correctly (as in solve the puzzle) answer the challenge they had been presented with, the first time never getting there, the second not getting there until the stab was outside of a previously unknown box that would allow it to be manually rolled back into more usable territory. The follow-on to this statement is that both crashes were the fault of the crews for failing the most basic of tasks- to fly the airplane.

Statement 2: Many of us here feel that there is a deep and very real culpability within Boeing and the FAA for creating such a lethal design. In this case (this is all entirely hypothetical, please work with the suggestion rather than the actuality) an engineer was presented with a problem that needed to be solved. She and her team came up with MCAS. The person responsible for choosing the best course of design knew that MCAS would have a profound impact on the horizontal stab, and they chose to shoehorn it in there anyway. The flight-test crews knew of the system at least and failed to properly review it for (what are now) obvious technical and safety shortcomings. Then, in a further admission that they were pushing the envelope everyone involved at Boeing literally hid the existence of the system from the pilots and operators who would fly the airplane. That person(s) also misled the FAA by informing the feds that the maximum authority that MCAS would have was .6 of a degree, when in reality (and they knew this) it was 2.5 degrees at a whack. In a final insult they said "all you need is an hour with this here tablet-thingy and you will know all you need to know to safely command and fly the MAX series of aircraft!!

With those two statements on offer- and the acknowledgement that there is plenty of blame to go around, the question I have is why are you not focusing on Boeing, the corporate culture that created this monster, the profit-driven betrayal of everyone here, and the fact that they are clearly working to pull a rabbit out of the hat in lieu of actually starting over again- which is what any rational society would require them to do. Yes, we know who the four crew members are, so that makes them easy targets, but if the professionals on this forum are willing to eat their own while looking the other way as Boeing goes about its PR campaign then what does that really say about all of us??

Warm regards-
dce
Almost 5000 posts later it is clear it doesn't matter what professional 737 pilots will say about this issue. You guys have made up your mind and no facts will get in the way of that opinion. Nonetheless I will give it another try even though what I am about to write has probably already been mentioned several times:

The MCAS system obviously should have been designed better but the press makes it seem as if Boeing knew the system created great risks but they went ahead with it anyway in order to make more profit. That thought in itself is so absurd that arguing with anyone who believes it, is basically pointless. If Boeing had thought these accidents were likely to occur they would have designed the system differently.

What does this MCAS monster as you call it actually do? It lowers the nose of the aircraft by changing the position of the horizontal stabilizer. It doesn't make the wings fall off, it doesn't set the plane on fire... it only moves the horizontal stabilizer. There is a switch on the pilots control column which moves the horizontal stabilizer and it overrides MCAS each time. I know you guys do not want to face it, but it really is that simple. Now if someone is reading this, thinking if it was that simple why didn't the pilots just do it? First of all they did. The Lion Air Captain did it at least twenty times. And the Ethiopian Captain did trim out the MCAS induced movement completely the second time it activated. So we could already talk a lot about why they didn't do it the whole time, then lower the flaps for landing (MCAS deactivates) and land. Aside from the fact that they did use the trim switch a little bit at least. please have a look at Asiana flight 214, Emirates 521, or Turkish 1951. These are only a few examples of flights were pilots failed to do the most basic thing: flying the aircraft. There were other causes as well and in the case of Turkish and Asiana the flights were not stabilized at 1000 Feet which means they should have carried out a go around preventing both accidents even before the mistake of not flying the aircraft (speed control) was made.


What these accidents show you is that pilots will crash aircraft even though it would have been very easy not to. In the case of Asiana and Emirates there were not even any system failures. Why these things happen is a completely different issue and the answers are to be found in the human factors involved when people fly aircraft. The Fact is, planes crash because pilots do not carry out the basic steps involved in flying an aircraft.

Now one important point I would like to make to all the posters with their Skygod and hindsight comments: First of all, it isn't about blaming the pilots. It is about stating facts. If I or others state that the crew did not carry out the unreliable airspeed memory items when in fact Boeing requires a crew to so in the situation they were in, then that is stating a fact and has nothing to do with hindsight or blame. Stick shaker only on one side, several caution lights going on, differing airspeed indications create a very confusing situation. For exactly that reason there are memory items in order to deal with that situation and they must be carried out. This procedure is a life saver because in that situation it is nearly impossible to figure out which system is malfunctioning and what is actually going on. For that reason: AP off, AT off, FD both off, flaps extended 10 pitch 80% N1. This will set the airplane on a safe flight path and you will continue to climb away from the ground. Now you have time to figure out the problem. This is what we are trained for. This is our job. Carrying out these procedures in that situation has nothing to do with being a skygod and pointing out that the crew did not do it doesn't make us armchair pilots with hindsight. If there is an engine fire on take off I carry out my memory items, if there is a rapid depressurization I carry out my memory items. Again this is what we are trained for.

If the crew had done this on any of these flights we wouldn't even be talking about MCAS. I am not blaming the crew when I say they did no do this. The crew is always just a product of the training department and the general procedures of the airline they fly for. For example, in the case of the Emirates crash, the crew wanted to fly a go around. They only pushed the take off/go around button but did not actually move the thrust lever forward in order to increase thrust on the engines. These pilots were not idiots. I can completely understand how this could happen. Normally as long as the automatic thrust control is engaged, pushing the TOGA button will increase thrust. However, shortly after touch down the automatic thrust control is automatically disengaged. Emirates is an airline with procedures that will not allow pilots to fly manually with the flight directors off for example. I can understand how a crew that is trained to rely on automation will not think to actually move the thrust levers and will not check if the thrust is increasing, despite procedures to do so. Basic skills are lost if one does not use them regularly.

The 737 MAX is grounded and will continue to be grounded for a long time because people think the airplane is unsafe. Furthermore the press reported the Ethiopian pilots carried out all the required procedures and yet they crashed. Why are people like me writing on this forum? It simply isn't true that the 737 MAX is inherently unsafe even with the "old" MCAS and it isn't true that the crew carried out the required procedures. That is not my opinion. That is a fact (again why they did not do it is another issue). If the established procedures had been carried out the planes would not have crashed. There was not one procedure done wrong but several done wrong. Each one of these procedures would have saved the aircraft. Carrying out the unreliable airspeed memory items is one procedure. If the pilots do not do this they are already entering an area where they are not flying the airplane according to procedure anymore but even in that case, carrying out the stab trim runaway memory items correctly once MCAS engaged (please stop these ridiculous comments that the MCAS activation cannot be recognized as a stab trim runaway) would also have saved the plane. If the pilots decide for whatever reason to not even do that, they still have the option of just trimming out the control forces each time MCAS activates (basic flying skills). Again when I am stating what they should have done according to procedure I am not blaming the pilots but only stating the facts of what Boeing says pilots must do in these situations and what we are trained for in our manuals and in the simulator. These recommended procedures would have saved the plane and please realize that there was a flight that had exactly the same problems and they did land safely (and they did not carry out unreliable airspeed mem items and also did not accurately carry out the stab trim mem items and still they saved the plane proving there are several options and it is not a react quickly or die situation).

Final comment: In my opinion crews that are not trained well and are lacking basic skills of flying the aircraft due to company policies are a far greater threat to aviation safety than any system design. I believe we still have a long way to go until we will design systems that never fail (if ever). So it will continue to be up to the pilots to save the day when systems malfunction. There needs to be a focus on enabling pilots to do so a lot more than focusing on how MCAS can be improved.

Last edited by 737mgm; 30th Apr 2019 at 07:40.
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Old 29th Apr 2019, 22:17
  #4609 (permalink)  
 
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Originally Posted by Alchad View Post

My answer to the question would be that apportioning blame is a second order to actually determining the cause/reason the planes crashed.


And my response would be that some people are having trouble seeing that, quite often, these are really two sides of the same coin.

To put it another way, if the accident investigation team determines that one of the primary causes was the poor design of MCAS, would Boeing be blameless?
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Old 29th Apr 2019, 22:29
  #4610 (permalink)  
 
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Better AOA

Why does the Raytheon uav not have outboard AoA sensors is there a far superior technology already , but maybe more difficult to maintain?
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Old 29th Apr 2019, 23:23
  #4611 (permalink)  
 
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SWA claim they thought they had AOA Disagree

"Southwest Airlines says Boeing didn't disclose it had deactivated safety alert on 737 Max jets"

So says Bloomberg, quoting the WSJ. I shan't copy-paste the article here, and I don't believe I can post a link, but the essence is that SWA are stating that their manuals showed the AOA Disagree alert as being a standard feature, not optional, and that they did not know it was optional until after the Lion Air incident. They're also saying that the AOA Disagree alert was standard fit on the NG.
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Old 29th Apr 2019, 23:58
  #4612 (permalink)  
 
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Trimming out the control forces is an instinctive and unconscious action that 737 Driver has so nicely articulated that is a fundamental skill that pilots with 5 hours of flying time have.
This statement is exactly why I feel that we do not have the complete picture yet. When the trace shows that at least two different pilots did something completely counterintuitive (a few short bursts on the trim rather than holding it down) when they really, really wanted to make the plane go UP instead of DOWN, I think that there is a factor that we do not know about yet. I can't imagine anybody not continuously holding the "UP" switch when they see ground in the windshield, it is just not the way humans operate. You can see Formula 1 drivers adjusting the steering wheel while their car goes airborne, people try to turn on the lights when the power is out, the helmsman will pull on the throttles as the ship with dead engines inexorably heads to crush the wharf, etc. It defies reason that none of the four pilots held the button down to the last.

I don't know what it could be (can you break the switches by pressing too hard on them?)
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Old 30th Apr 2019, 00:00
  #4613 (permalink)  
 
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Originally Posted by 737 Driver View Post
Are you more interesting in bitching or saving lives?
Have you considered that bitching may save lives? Without extensive "bitching" against Boeing and the FAA from the pilot community, even going as far as being considered "hysterical" by some, the responsible parties at Boeing and the FAA may just conclude that pilots will accept whatever shit system they will come up with and respectively certify, and at some point the public will forget and carry on flying on those flawed machines. How is that a good thing for safety?

I would love nothing more than having all the holes in the layers of cheese patched, including any deficiencies in pilot training. That may require bitching too, not just towards Boeing and the FAA, but also towards the airlines that are extremely reluctant to give the pilots more than a few hours of training, and no simulator training if at all possible.

I think sometimes an attitude along the lines of "I'm mad as Hell and I'm not going to take this anymore" is required to make the responsible parties realize this cannot continue, and fundamental changes must be made. In my opinion that should start with the FAA being given the appropriate budget and independence from political influence to be able to properly regulate both the airlines and the aircraft manufactures, forcing them to "produce" both safe aircrafts and safe pilots respectively.

As a passenger, I will try my best to avoid Boeing aircraft until that actually happens.
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Old 30th Apr 2019, 00:15
  #4614 (permalink)  
 
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Originally Posted by MemberBerry View Post
Have you considered that bitching may save lives? Without extensive "bitching" against Boeing and the FAA from the pilot community, even going as far as being considered "hysterical" by some, the responsible parties at Boeing and the FAA may just conclude that pilots will accept whatever shit system they will come up with and respectively certify, and the public at some point will forget and carry on flying on those flawed machines. How is that a good thing for safety?
I would suggest that if you want to bitch to Boeing, then bitch to Boeing. If you want to bitch to the FAA, then bitch to the FAA (perhaps through your Congressman). I'm pretty sure that neither Boeing nor the FAA are reading these posts. Even if they were, armies of lawyers are firing multi-hundred page briefs across the bow of all the agencies I listed in items 1 thru 4. Anything posted here is a mere fart in a windstorm compared to that onslaught.
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Old 30th Apr 2019, 00:19
  #4615 (permalink)  
 
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Originally Posted by Water pilot View Post
This statement is exactly why I feel that we do not have the complete picture yet. When the trace shows that at least two different pilots did something completely counterintuitive (a few short bursts on the trim rather than holding it down) when they really, really wanted to make the plane go UP instead of DOWN, I think that there is a factor that we do not know about yet.
You can find a fairly comprehensive review at the following link which includes some reasonable speculation as to why the pilots did not trim sufficiently during the final moments:

https://www.satcom.guru/2019/04/what...-on-et302.html​​​​​​
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Old 30th Apr 2019, 00:44
  #4616 (permalink)  
 
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Originally Posted by 737 Driver View Post
You can find a fairly comprehensive review at the following link which includes some reasonable speculation as to why the pilots did not trim sufficiently during the final moments:

https://www.satcom.guru/2019/04/what...-on-et302.html​​​​​​
Thanks for the link, but note that they shrug their shoulders as well:
In any case, it is not clear what prevented the crew from continuing to trim airplane nose up to reduce column forces.
This is something that needs to be figured out, and I hope that Boeing's internal practice is different than their public stance that three independent aircrews (the first crew did not respond properly, either) were not skilled enough to fly their plane. They need to test this scenario to failure in the sim, find the worst line pilots imaginable, the ones quite close to being terminated but still qualified, and put them through this scenario and see what they do. If they can't replicate the scenario, something else is wrong.

Boeing's conclusion that pilots are unqualified to fly the MAX -- and that is their conclusion, and the conclusion of many here -- is at odds with their stance that a 15 minute IPAD session will fix everything. Boeing markets the plane as being flyable by pilots that meet industry standards and either the plane is not flyable by pilots who meet those standards (you can't argue with two crashes in six months) or there is something wrong with the plane. The latter is far easier to fix.

Last edited by Water pilot; 30th Apr 2019 at 03:52.
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Old 30th Apr 2019, 00:50
  #4617 (permalink)  
 
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Originally Posted by 737mgm View Post

Stick shaker only on one side, several caution lights going on, differing airspeed indications create a very confusing situation. For exactly that reason there are memory items in order to deal with that situation and they must be carried out.
...
There was not one procedure done wrong but several done wrong. Each one of these procedures would have saved the aircraft. Carrying out the unreliable airspeed memory items is one procedure
.
Things are never as black and white as one might wish. The ET pilots were not at all perfect but they were also misserved by the system.

This is text from a Boeing UAS flow chart someone posted a while back, not I do not have access to current procedures,although what probably matters as much is what was in effect when the Pilot was trained.
Seems totally reasonable to decide it is false AoA related warning.

AoA sensor failure on Takeoff
If AoA sensor is failed high,stick shaker on failed side will activate on rotation accompanied by IAS/ALT disagree warning flags.

If the pitch power and config are consistent with takeoff and the good side ASI agrees with the Standby ASI,then it is a false warning

There is a side arrow to the side that states "If in any doubt execute the UAS NNC"

The pilot with good side data becomes PF

Land immediately
With a 360 hour co-pilot there may be a reason the Captain retained control, especially with relatively small ASI difference.

Originally Posted by 737mgm View Post

And the Ethiopian Captain did trim out the MCAS induced movement completely the second time it activated. So we could already talk a lot about why they didn't do it the whole time, then lower the flaps for landing (MCAS deactivates) and land.
...
...
even in that case, carrying out the stab trim runaway memory items correctly once MCAS engaged (please stop these ridiculous comments that the MCAS activation cannot be recognized as a stab trim runaway) would also have saved the plane.
Note, the times below are from the FDR chart which is hard to read better than a second or so due to ambiguous sloping edges on binary traces.

The first MCAS trim started at 05:40:00 ending about 9 seconds later, this was as the autopilot dropped out after flap retraction.

The pilot only partially unwound the trim at 05:40:15, 5 seconds later the second MCAS input started but was cancelledby sustained pilot trim starting at 05:40:29.
This second trim attempt lasted until the stab trim was cutout.
From the prelim report:
At 05:40:35, the First-Officer called out “stab trim cut-out” two times. Captain agreed and First-Officer confirmed stab trim cut-out.
Given that Boeing changed the cutout switch functions on the MAX so that either one disabled all electric trim whereas on NG the right switch disabled automatic trim only it is possible/likely that the pilot was still trying to trim.
Much later the (very sparse) partial transcript has this:

At 05:41:46, the Captain asked the First-Officer if the trim is functional. The First-Officer has replied that the trim was not working and asked if he could try it manually. The Captain told him to try. At 05:41:54, the First-Officer replied that it is not working.
This supports the idea that they believed they had only disabled automatic trim and manual electric trim should still function.
This difference is not highlighted, or mentioned at all depending on which MAX type conversion powerpoint the crew used.

Bottom line is that runaway trim nnc was executed but they were (apparently) left with an inability to crank the trim wheel.
"Unloading" maneuvers used to be part of runaway stab training but apparently were dropped some time ago.

To anyone contemplating commenting on the emergency AD stating to trim first if MCAS runway:
A: That was buried as a note -after- action items.
B: ET pilots company may have failed to update manuals.

Of course it is tragic that they did not input sustained trim after an apparent last ditch effort where they re-enabled electric trim. I still wonder if some other factor is at work here since almost exactly the same thing is seen at end of Lion Air traces.

There was less than 45 seconds from start of first MCAS trim to loosing all trim capability.

They might have done better had they not followed the runaway trim procedure.

I do totally agree on your points on the state of training and company policy that result in poor confidence in manual skills, this undoubtedly also played a significant role in this accident.

Note I see several other responses on trim failure while I wrote this, the above is one (of several) possible scenarios.

Last edited by MurphyWasRight; 30th Apr 2019 at 00:55. Reason: typo
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Old 30th Apr 2019, 02:28
  #4618 (permalink)  
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Water pilot:
This statement is exactly why I feel that we do not have the complete picture yet. When the trace shows that at least two different pilots did something completely counterintuitive (a few short bursts on the trim rather than holding it down) when they really, really wanted to make the plane go UP instead of DOWN, I think that there is a factor that we do not know about yet. I can't imagine anybody not continuously holding the "UP" switch when they see ground in the windshield, it is just not the way humans operate.
I still don't understand that 'noise' where there should be steady nose-up trim. Shaking stick suggested. Not convinced.


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Old 30th Apr 2019, 03:37
  #4619 (permalink)  
 
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MCAS Working as (poorly) Designed - AoA fails occasionally

I am wondering how much negative g was produced in the cockpit with the final two MCAS excursions past Vmo. I remember being a front seat passenger when our car rear-ended another car. My legs flew up even though I was strapped in and braced. The driver wasn't and fractured a foot. The accident crews were not military pilots experienced with serious g.

Should we not have a careful look at the stick shaker NNC, given that a failed AoA is setting up the crew for the MCAS knock out combo punch?

I like that at least one pilot suggests pulling the stick shaker breaker once a safe flight path is established.

If failed AoA on one side, is there a way to switch SMYDs - and then perhaps see if the other AoA is correct (sure would like to see three)?

And how about an NNC item to keep flaps down unless switched to a good AOA - that or cut out the automatic trim first?

I am well experienced with non air carrier aviation organisations that sometimes set up pilots to kill themselves (all with the best intentions) and have witnessed a fatality, injury, hull losses, serious incidents and narrow escapes.

A certain paranoia is beneficial, including towards your own attitude.

​​​​In the kingdom of SOPs and multiple checklists, we and management (operator and manufacturer) tend to believe the cotton wool it envelopes us in will protect against all ills we have foreseen.

Works pretty good until something unforseen pops up when the crew better have 737driver's mantra in their back pocket - unless you're in a glider.
RatherBeFlying is offline  
Old 30th Apr 2019, 06:23
  #4620 (permalink)  
 
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Originally Posted by Water pilot View Post
This statement is exactly why I feel that we do not have the complete picture yet. When the trace shows that at least two different pilots did something completely counterintuitive (a few short bursts on the trim rather than holding it down) when they really, really wanted to make the plane go UP instead of DOWN, I think that there is a factor that we do not know about yet. I can't imagine anybody not continuously holding the "UP" switch when they see ground in the windshield, it is just not the way humans operate. You can see Formula 1 drivers adjusting the steering wheel while their car goes airborne, people try to turn on the lights when the power is out, the helmsman will pull on the throttles as the ship with dead engines inexorably heads to crush the wharf, etc. It defies reason that none of the four pilots held the button down to the last.

I don't know what it could be (can you break the switches by pressing too hard on them?)
Originally Posted by RatherBeFlying View Post
I am wondering how much negative g was produced in the cockpit with the final two MCAS excursions past Vmo.
I could be wrong but I thought it was clear that it was a full negative 2 Gs, partially due to the crew losing control of the yokes with the last nose down input. Additionally, to Water pilot's point I think that due to the fact that the aircraft was well past Vmo it would appear that the short bursts of nose up trim resulted in very high momentary positive G forces. I firmly believe the crew stopped trimming nose up due to the momentarily high positive Gs on the aircraft...and 5 seconds later the unthinkable happened. Remember, the power is still set at TO, and is accelerating all this time, especially when pointing downward. A high speed nose-down trim input at Vmo+ can't be pretty...
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