kalvado wrote:

XRAYretired wrote:

kalvado wrote:

Should we believe Boeing that they started working on MCAS update back then? As it was pointed out, they have financial reasons to paint things beautiful. Then, does it take that long to do one procedure? How many decades does it take to design new plane with such pace?
Last, but not the least... What was supposed to be a quick fix is not submitted to FAA yet.
My bet whatever (and IF anything) was done after lion crash was inadequate and real work started some time in April..

Six months is prety quick for a modification to safety critical flight control software. Dont forget, as well as validating the change to the procedures intended, you must also verify that everything else continues to function as intended when the change is integrated into the whole. If anything, I would suggest the quick change is actually indicative of a concern that the gamble taken to keep the max in service and get the change in before another event might be lost. It was. A further delay was acrued due to a problem found with the flap system. It may have been identified as a result of verification of the MCAS change or a separate review convened due to the events.

Reason for the current delay? anybodies guess, but it may be related to the review of NNCs/Training with Boeing wanting to submit a whole change pack in one go and not have manual changes outstanding.

Ray

Which is basically saying that there was no system in software development, there were no proper component tests, no modularity. Which seems pretty accurate given what happened to MCAS - and way more scary than anything said so far about MAX.
Again, we had Toyota fiasco - which was exactly that situation.

@kalvado" Agreed. If you haven't read it you may find this article interesting https://spectrum.ieee.org/aerospace/avi ... -developer

planecane wrote:

smartplane wrote:

planecane wrote:

The point I was trying to make is that the situation of use of the manual trim wheel under extreme loads is in the NG training manual. The media articles and some posters on here have made it seem like the pilots had absolutely no idea what to do when the manual wheel is difficult to turn. Well, it appears to be in the TRAINING MANUAL. Therefore, pilots of the 737 should have been TRAINED to deal with the situation.

I know the next response is going to be how even the NG simulators didn't properly simulate the required force. However, mentour pilot's video shows that it takes plenty of effort under those conditions. Does it make a big difference that in the simulator it is really hard to turn but in reality it is really really hard?

If it's impossible to turn, unless both pilots use both hands, then it is a big difference.

But if the training manual says "In extreme cases it may be necessary to aerodynamically relieve the airloads to allow manual trimming. Accelerate or decelerate towards the in-trim speed while attempting to trim manually," shouldn't a crew figure out that when they can't turn the wheel, it is time to perform this action from their training? Of course, this assumes they were actually trained per the manual. I mean the manual for the NG pretty much says that there can be situations where manual trim is impossible without taking action to relieve the loads on the stabilizer.

This is part of runaway stabilizer training and I would expect ALL 737 type rated pilots to have been trained on it and know what to do. The ET crew probably would have crashed anyway at that point because it was so far out of trim, they were going so fast and they were so low. However, the fact that they didn't attempt it either indicates that they didn't try the manual wheel or they were not properly trained for this situation.

Perhaps your training expectation might be a little wishful-

avherald.com/h?article=4c534c4a/0045&opt=0
'the first 737-8 MAX simulator was put into service mid January 2019. Only in March 2019 a trim runaway lesson was included in the NG and MAX training syllabus. Flight crew are scheduled to go through a simulator session every 6 months (as per industry standards), the accident flight crew may thus not yet have received training on a stabilizer trim runaway (in the NG or MAX Simulator).'

As regards manual trim wheel attempt-
There are only two options available: MANUAL electric TRIM and MANUAL TRIM wheel.

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 the First-Officer replied that it is not working.

I think it is unlikely that the F/O would use two different terms for the same function in the same sentence and would not asking the Capt. to confirm trying the same function is checked for a second time using two terms. But two terms are used. The only satisfactory conclusion is that the F/O is referring to both functions. The question is which term refers to which function.

My suggestion is that, remembering that it was FO that offered STAB TRIM CUT-OUT ~1 min. before hand and the Capt. seemed unsure in his response, that the Capt. was asking for confirmation that manual electric TRIM was not available, that the FO confirmed not working, because it was in cut-out, and then suggested to try MANUAL trim wheel - also not working.

Ray

kalvado wrote:

XRAYretired wrote:

kalvado wrote:

Should we believe Boeing that they started working on MCAS update back then? As it was pointed out, they have financial reasons to paint things beautiful. Then, does it take that long to do one procedure? How many decades does it take to design new plane with such pace?
Last, but not the least... What was supposed to be a quick fix is not submitted to FAA yet.
My bet whatever (and IF anything) was done after lion crash was inadequate and real work started some time in April..

Six months is prety quick for a modification to safety critical flight control software. Dont forget, as well as validating the change to the procedures intended, you must also verify that everything else continues to function as intended when the change is integrated into the whole. If anything, I would suggest the quick change is actually indicative of a concern that the gamble taken to keep the max in service and get the change in before another event might be lost. It was. A further delay was acrued due to a problem found with the flap system. It may have been identified as a result of verification of the MCAS change or a separate review convened due to the events.

Reason for the current delay? anybodies guess, but it may be related to the review of NNCs/Training with Boeing wanting to submit a whole change pack in one go and not have manual changes outstanding.

Ray

Which is basically saying that there was no system in software development, there were no proper component tests, no modularity. Which seems pretty accurate given what happened to MCAS - and way more scary than anything said so far about MAX.
Again, we had Toyota fiasco - which was exactly that situation.

That was not what I was saying. If we ever get that level of detail, and I doubt it, I think we will find that the software design and implementation was validated as compliant with the requirements that were set. And it is the system design that was incompetent and driven by commercial imperatives.

Ray

XRAYretired wrote:

kalvado wrote:

XRAYretired wrote:

Six months is prety quick for a modification to safety critical flight control software. Dont forget, as well as validating the change to the procedures intended, you must also verify that everything else continues to function as intended when the change is integrated into the whole. If anything, I would suggest the quick change is actually indicative of a concern that the gamble taken to keep the max in service and get the change in before another event might be lost. It was. A further delay was acrued due to a problem found with the flap system. It may have been identified as a result of verification of the MCAS change or a separate review convened due to the events.

Reason for the current delay? anybodies guess, but it may be related to the review of NNCs/Training with Boeing wanting to submit a whole change pack in one go and not have manual changes outstanding.

Ray

Which is basically saying that there was no system in software development, there were no proper component tests, no modularity. Which seems pretty accurate given what happened to MCAS - and way more scary than anything said so far about MAX.
Again, we had Toyota fiasco - which was exactly that situation.

That was not what I was saying. If we ever get that level of detail, and I doubt it, I think we will find that the software design and implementation was validated as compliant with the requirements that were set. And it is the system design that was incompetent and driven by commercial imperatives.

Ray

You're basically saying that complex system needs serious verification. which is true. I am just questioning if it is feasible to have relatively minor change tested for half a year, given that the entire system had to be developed within mere few years. Proper software design should drastically reduce required times as a good portion of work - tests, interfaces etc - is already done.
As for requirements - apparently, whatever requirements were there, they were not followed. Again, see Toyota for a precedent. Boeing didn't say anything about their software development system and standards - which is a red flag in itself in present situation.

XRAYretired wrote:

planecane wrote:

smartplane wrote:

If it's impossible to turn, unless both pilots use both hands, then it is a big difference.

But if the training manual says "In extreme cases it may be necessary to aerodynamically relieve the airloads to allow manual trimming. Accelerate or decelerate towards the in-trim speed while attempting to trim manually," shouldn't a crew figure out that when they can't turn the wheel, it is time to perform this action from their training? Of course, this assumes they were actually trained per the manual. I mean the manual for the NG pretty much says that there can be situations where manual trim is impossible without taking action to relieve the loads on the stabilizer.

This is part of runaway stabilizer training and I would expect ALL 737 type rated pilots to have been trained on it and know what to do. The ET crew probably would have crashed anyway at that point because it was so far out of trim, they were going so fast and they were so low. However, the fact that they didn't attempt it either indicates that they didn't try the manual wheel or they were not properly trained for this situation.

Perhaps your training expectation might be a little wishful-

avherald.com/h?article=4c534c4a/0045&opt=0
'the first 737-8 MAX simulator was put into service mid January 2019. Only in March 2019 a trim runaway lesson was included in the NG and MAX training syllabus. Flight crew are scheduled to go through a simulator session every 6 months (as per industry standards), the accident flight crew may thus not yet have received training on a stabilizer trim runaway (in the NG or MAX Simulator).'

As regards manual trim wheel attempt-
There are only two options available: MANUAL electric TRIM and MANUAL TRIM wheel.

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 the First-Officer replied that it is not working.

I think it is unlikely that the F/O would use two different terms for the same function in the same sentence and would not asking the Capt. to confirm trying the same function is checked for a second time using two terms. But two terms are used. The only satisfactory conclusion is that the F/O is referring to both functions. The question is which term refers to which function.

My suggestion is that, remembering that it was FO that offered STAB TRIM CUT-OUT ~1 min. before hand and the Capt. seemed unsure in his response, that the Capt. was asking for confirmation that manual electric TRIM was not available, that the FO confirmed not working, because it was in cut-out, and then suggested to try MANUAL trim wheel - also not working.

Ray

I agree that the FO most likely tried the trim wheel.

With respect to training, why is my expectation wishful? If there is a section on runaway stabilizer in the training manual, shouldn't that be something that is trained for? The fact that it wasn't added by ET until March 2019 proves to me that there are training issues at least at ET and most likely at more airlines. What is the point of a training manual if the situations in it aren't included in the syllabus? If there is poor training on the 737 there is likely poor training on other aircraft.

The fact that Boeing royally screwed up MCAS should not make this training issue be glossed over. If the crew had been properly trained, they would have been much more likely to save the aircraft.

kalvado wrote:

XRAYretired wrote:

kalvado wrote:

Which is basically saying that there was no system in software development, there were no proper component tests, no modularity. Which seems pretty accurate given what happened to MCAS - and way more scary than anything said so far about MAX.
Again, we had Toyota fiasco - which was exactly that situation.

That was not what I was saying. If we ever get that level of detail, and I doubt it, I think we will find that the software design and implementation was validated as compliant with the requirements that were set. And it is the system design that was incompetent and driven by commercial imperatives.

Ray

You're basically saying that complex system needs serious verification. which is true. I am just questioning if it is feasible to have relatively minor change tested for half a year, given that the entire system had to be developed within mere few years. Proper software design should drastically reduce required times as a good portion of work - tests, interfaces etc - is already done.
As for requirements - apparently, whatever requirements were there, they were not followed. Again, see Toyota for a precedent. Boeing didn't say anything about their software development system and standards - which is a red flag in itself in present situation.

Toyota is not a precedent except for how not to develop safety related systems maybe. They would not have got anywhere near Aerospace. I don't criticise Boeing for not saying anything about software development processes, there are few folks around who have the knowledge to understand it.

Proportionally, I would say that a modified line of safety critical code takes more time than one newly written (design, implementation, verification and validation). I believe the design and implementation of the MCAS or change to MCASV2.0 would not have commenced before the requirements were set by the system design. Suggest have a look at RTCA/DO-178, the Boeing (and/or sub-contractor?) systems would be required to comply with it.

Again, 6 months seems OK to me, especially that maybe two months of that is flight testing.

Ray

XRAYretired wrote:

kalvado wrote:

XRAYretired wrote:

That was not what I was saying. If we ever get that level of detail, and I doubt it, I think we will find that the software design and implementation was validated as compliant with the requirements that were set. And it is the system design that was incompetent and driven by commercial imperatives.

Ray

You're basically saying that complex system needs serious verification. which is true. I am just questioning if it is feasible to have relatively minor change tested for half a year, given that the entire system had to be developed within mere few years. Proper software design should drastically reduce required times as a good portion of work - tests, interfaces etc - is already done.
As for requirements - apparently, whatever requirements were there, they were not followed. Again, see Toyota for a precedent. Boeing didn't say anything about their software development system and standards - which is a red flag in itself in present situation.

Toyota is not a precedent except for how not to develop safety related systems maybe. They would not have got anywhere near Aerospace. I don't criticise Boeing for not saying anything about software development processes, there are few folks around who have the knowledge to understand it.

Proportionally, I would say that a modified line of safety critical code takes more time than one newly written (design, implementation, verification and validation). I believe the design and implementation of the MCAS or change to MCASV2.0 would not have commenced before the requirements were set by the system design. Suggest have a look at RTCA/DO-178, the Boeing (and/or sub-contractor?) systems would be required to comply with it.

Again, 6 months seems OK to me, especially that maybe two months of that is flight testing.

Ray

And again, Toyota claimed to follow standards, until it turned out they didn't. I don't buy airspace argument as such - Boeing engineers are still human beings, and you wouldn't really tell Ford engineer from Boeing engineer without seeing a badge. (Toyota vs Boeig may be a bit easier, though).

planecane wrote:

XRAYretired wrote:

planecane wrote:

But if the training manual says "In extreme cases it may be necessary to aerodynamically relieve the airloads to allow manual trimming. Accelerate or decelerate towards the in-trim speed while attempting to trim manually," shouldn't a crew figure out that when they can't turn the wheel, it is time to perform this action from their training? Of course, this assumes they were actually trained per the manual. I mean the manual for the NG pretty much says that there can be situations where manual trim is impossible without taking action to relieve the loads on the stabilizer.

This is part of runaway stabilizer training and I would expect ALL 737 type rated pilots to have been trained on it and know what to do. The ET crew probably would have crashed anyway at that point because it was so far out of trim, they were going so fast and they were so low. However, the fact that they didn't attempt it either indicates that they didn't try the manual wheel or they were not properly trained for this situation.

Perhaps your training expectation might be a little wishful-

avherald.com/h?article=4c534c4a/0045&opt=0
'the first 737-8 MAX simulator was put into service mid January 2019. Only in March 2019 a trim runaway lesson was included in the NG and MAX training syllabus. Flight crew are scheduled to go through a simulator session every 6 months (as per industry standards), the accident flight crew may thus not yet have received training on a stabilizer trim runaway (in the NG or MAX Simulator).'

As regards manual trim wheel attempt-
There are only two options available: MANUAL electric TRIM and MANUAL TRIM wheel.

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 the First-Officer replied that it is not working.

I think it is unlikely that the F/O would use two different terms for the same function in the same sentence and would not asking the Capt. to confirm trying the same function is checked for a second time using two terms. But two terms are used. The only satisfactory conclusion is that the F/O is referring to both functions. The question is which term refers to which function.

My suggestion is that, remembering that it was FO that offered STAB TRIM CUT-OUT ~1 min. before hand and the Capt. seemed unsure in his response, that the Capt. was asking for confirmation that manual electric TRIM was not available, that the FO confirmed not working, because it was in cut-out, and then suggested to try MANUAL trim wheel - also not working.

Ray

I agree that the FO most likely tried the trim wheel.

With respect to training, why is my expectation wishful? If there is a section on runaway stabilizer in the training manual, shouldn't that be something that is trained for? The fact that it wasn't added by ET until March 2019 proves to me that there are training issues at least at ET and most likely at more airlines. What is the point of a training manual if the situations in it aren't included in the syllabus? If there is poor training on the 737 there is likely poor training on other aircraft.

The fact that Boeing royally screwed up MCAS should not make this training issue be glossed over. If the crew had been properly trained, they would have been much more likely to save the aircraft.

Why are you shooting the messenger? Wasnt me who decided what is or is not trained, nor me who would justify not training stabiliser runaway. Nor is providing available information on training glossing over it, the opposite I would suggest. Anyway, the syllabus referred to, I would expect, likely applies generally for all operators not just ET.

Ray

XRAYretired wrote:

planecane wrote:

XRAYretired wrote:

Perhaps your training expectation might be a little wishful-

avherald.com/h?article=4c534c4a/0045&opt=0
'the first 737-8 MAX simulator was put into service mid January 2019. Only in March 2019 a trim runaway lesson was included in the NG and MAX training syllabus. Flight crew are scheduled to go through a simulator session every 6 months (as per industry standards), the accident flight crew may thus not yet have received training on a stabilizer trim runaway (in the NG or MAX Simulator).'

As regards manual trim wheel attempt-
There are only two options available: MANUAL electric TRIM and MANUAL TRIM wheel.

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 the First-Officer replied that it is not working.

I think it is unlikely that the F/O would use two different terms for the same function in the same sentence and would not asking the Capt. to confirm trying the same function is checked for a second time using two terms. But two terms are used. The only satisfactory conclusion is that the F/O is referring to both functions. The question is which term refers to which function.

My suggestion is that, remembering that it was FO that offered STAB TRIM CUT-OUT ~1 min. before hand and the Capt. seemed unsure in his response, that the Capt. was asking for confirmation that manual electric TRIM was not available, that the FO confirmed not working, because it was in cut-out, and then suggested to try MANUAL trim wheel - also not working.

Ray

I agree that the FO most likely tried the trim wheel.

With respect to training, why is my expectation wishful? If there is a section on runaway stabilizer in the training manual, shouldn't that be something that is trained for? The fact that it wasn't added by ET until March 2019 proves to me that there are training issues at least at ET and most likely at more airlines. What is the point of a training manual if the situations in it aren't included in the syllabus? If there is poor training on the 737 there is likely poor training on other aircraft.

The fact that Boeing royally screwed up MCAS should not make this training issue be glossed over. If the crew had been properly trained, they would have been much more likely to save the aircraft.

Why are you shooting the messenger? Wasnt me who decided what is or is not trained, nor me who would justify not training stabiliser runaway. Nor is providing available information on training glossing over it, the opposite I would suggest. Anyway, the syllabus referred to, I would expect, likely applies generally for all operators not just ET.

Ray

Sorry if it came off that way, I wasn't directing my response at you. Since your post pointed out the syllabus issue I just used it as a base to put the training issue out there.

planecane wrote:

XRAYretired wrote:

planecane wrote:

I agree that the FO most likely tried the trim wheel.

With respect to training, why is my expectation wishful? If there is a section on runaway stabilizer in the training manual, shouldn't that be something that is trained for? The fact that it wasn't added by ET until March 2019 proves to me that there are training issues at least at ET and most likely at more airlines. What is the point of a training manual if the situations in it aren't included in the syllabus? If there is poor training on the 737 there is likely poor training on other aircraft.

The fact that Boeing royally screwed up MCAS should not make this training issue be glossed over. If the crew had been properly trained, they would have been much more likely to save the aircraft.

Why are you shooting the messenger? Wasnt me who decided what is or is not trained, nor me who would justify not training stabiliser runaway. Nor is providing available information on training glossing over it, the opposite I would suggest. Anyway, the syllabus referred to, I would expect, likely applies generally for all operators not just ET.

Ray

Sorry if it came off that way, I wasn't directing my response at you. Since your post pointed out the syllabus issue I just used it as a base to put the training issue out there.

OK, sorry for my miss-interpretation, I get used to ducking on these threads.

Ray

Here is a new article about the 737 MAX and MCAS.

https://www.nytimes.com/2019/06/01/busi ... crash.html

The point that was new to me was that Boeing discovered they could have low speed stalls as well as the high speed stalls that have been talked about. So they could not use a g force sensor and AoA to determine when MCAS kicked in. And, as everyone knows, they only used one AoA sensor assuming pilots could get them out of situations.

MrBretz wrote:

Here is a new article about the 737 MAX and MCAS.

https://www.nytimes.com/2019/06/01/busi ... crash.html

The point that was new to me was that Boeing discovered they could have low speed stalls as well as the high speed stalls that have been talked about. So they could not use a g force sensor and AoA to determine when MCAS kicked in. And, as everyone knows, they only used one AoA sensor assuming pilots could get them out of situations.

This is a very logical article and explains the MAX timeline and how and who made the decisions regarding MCAS and the resulting overlook of critical design data. The rush to get the plane to market without asking the what ifs and O'h shits.

From the NYT article, this tidbit from one of the Test Pilots: "...Mr. Craig, who had been with Boeing since 1988, didn’t like it, according to one person involved in the testing. An old-school pilot, he eschewed systems that take control from pilots and would have preferred an aerodynamic fix such as vortex generators, thin fins on the wings. But engineers who tested the Max design in a wind tunnel weren’t convinced they would work, the person said...."

I'm by no needs an engineer, but I wonder what would happen if "Whitcomb bumps", like the ones that were installed on the Convair 990 might help to redirect airflow behind the raised engine nacelle? Those were originally designed to reduce shockwaves, but could it help to reduce effects of the larger nacelles, and the nose up problem??

Throwing it out there....

MrBretz wrote:

Here is a new article about the 737 MAX and MCAS.

https://www.nytimes.com/2019/06/01/busi ... crash.html

The point that was new to me was that Boeing discovered they could have low speed stalls as well as the high speed stalls that have been talked about. So they could not use a g force sensor and AoA to determine when MCAS kicked in. And, as everyone knows, they only used one AoA sensor assuming pilots could get them out of situations.

Safety analysis was done by people who don't know how the procedure is initiated.
High-speed system tweaked to work at low speeds with the same response across the range.
Safety actions are done based on a single e-mail.
Fix barely address variability within envelope...

I hope someone at EASA takes notes....

kalvado wrote:

MrBretz wrote:

Here is a new article about the 737 MAX and MCAS.

https://www.nytimes.com/2019/06/01/busi ... crash.html

The point that was new to me was that Boeing discovered they could have low speed stalls as well as the high speed stalls that have been talked about. So they could not use a g force sensor and AoA to determine when MCAS kicked in. And, as everyone knows, they only used one AoA sensor assuming pilots could get them out of situations.

Safety analysis was done by people who don't know how the procedure is initiated.
High-speed system tweaked to work at low speeds with the same response across the range.
Safety actions are done based on a single e-mail.
Fix barely address variability within envelope...

I hope someone at EASA takes notes....

I wish they would have asked why they couldn't keep the g force sensor in the loop at high speed and go to AoA sensor only at low speed. At least then if MCAS failed due to only an AoA sensor maybe it would have been slow enough to allow manual trim use and not need as much force on the column to counteract. I don't know what they are considering low speed in the article.

MrBretz wrote:

Here is a new article about the 737 MAX and MCAS.

https://www.nytimes.com/2019/06/01/busi ... crash.html

The point that was new to me was that Boeing discovered they could have low speed stalls as well as the high speed stalls that have been talked about. So they could not use a g force sensor and AoA to determine when MCAS kicked in. And, as everyone knows, they only used one AoA sensor assuming pilots could get them out of situations.

Great article by The New York Times. But it also fails to explain why MCAS wasn't reliant on both AoA sensors.

Only explanation I've seen on why the second sensor was not connected to MCAS comes from 60 minutes Australia. They claim that a Boeing whistleblower said that had the second sensor been used by MCAS, then the system would have been considered a "two sensor-system" which by definition would have required more thourough review by the FAA. Please let us hope that this is not the reason behind the single sensor "solution". If true, it would be disastrous for Boeing.

planecane wrote:

kalvado wrote:

MrBretz wrote:

Here is a new article about the 737 MAX and MCAS.

https://www.nytimes.com/2019/06/01/busi ... crash.html

The point that was new to me was that Boeing discovered they could have low speed stalls as well as the high speed stalls that have been talked about. So they could not use a g force sensor and AoA to determine when MCAS kicked in. And, as everyone knows, they only used one AoA sensor assuming pilots could get them out of situations.

Safety analysis was done by people who don't know how the procedure is initiated.
High-speed system tweaked to work at low speeds with the same response across the range.
Safety actions are done based on a single e-mail.
Fix barely address variability within envelope...

I hope someone at EASA takes notes....

I wish they would have asked why they couldn't keep the g force sensor in the loop at high speed and go to AoA sensor only at low speed. At least then if MCAS failed due to only an AoA sensor maybe it would have been slow enough to allow manual trim use and not need as much force on the column to counteract. I don't know what they are considering low speed in the article.

The way I read it is that MCAS was designed for one flight regime, then modified to fit another flight regime; now it is relaxed to fit no flight conditions, and MAX will fail both high and low speed handling tests. I hope MCAS 3.0 is underway...

14ccKemiskt wrote:

MrBretz wrote:

Here is a new article about the 737 MAX and MCAS.

https://www.nytimes.com/2019/06/01/busi ... crash.html

The point that was new to me was that Boeing discovered they could have low speed stalls as well as the high speed stalls that have been talked about. So they could not use a g force sensor and AoA to determine when MCAS kicked in. And, as everyone knows, they only used one AoA sensor assuming pilots could get them out of situations.

Great article by The New York Times. But it also fails to explain why MCAS wasn't reliant on both AoA sensors.

Only explanation I've seen on why the second sensor was not connected to MCAS comes from 60 minutes Australia. They claim that a Boeing whistleblower said that had the second sensor been used by MCAS, then the system would have been considered a "two sensor-system" which by definition would have required more thourough review by the FAA. Please let us hope that this is not the reason behind the single sensor "solution". If true, it would be disastrous for Boeing.

That makes no sense. Why would a more redundant system cause them to fear a more thorough review and why would the FAA review single sensor systems less thoroughly?

What is more likely is STS only used one AoA sensor so MCAS only used one sensor.

freakyrat wrote:

MrBretz wrote:

Here is a new article about the 737 MAX and MCAS.

https://www.nytimes.com/2019/06/01/busi ... crash.html

The point that was new to me was that Boeing discovered they could have low speed stalls as well as the high speed stalls that have been talked about. So they could not use a g force sensor and AoA to determine when MCAS kicked in. And, as everyone knows, they only used one AoA sensor assuming pilots could get them out of situations.

This is a very logical article and explains the MAX timeline and how and who made the decisions regarding MCAS and the resulting overlook of critical design data. The rush to get the plane to market without asking the what ifs and O'h shits.

There was no need for a rush. Boeing is a large corporation with all the resources available that are required for considered strategic planning.

7BOEING7 wrote:

smartplane wrote:

planecane wrote:

The point I was trying to make is that the situation of use of the manual trim wheel under extreme loads is in the NG training manual. The media articles and some posters on here have made it seem like the pilots had absolutely no idea what to do when the manual wheel is difficult to turn. Well, it appears to be in the TRAINING MANUAL. Therefore, pilots of the 737 should have been TRAINED to deal with the situation.

I know the next response is going to be how even the NG simulators didn't properly simulate the required force. However, mentour pilot's video shows that it takes plenty of effort under those conditions. Does it make a big difference that in the simulator it is really hard to turn but in reality it is really really hard?

If it's impossible to turn, unless both pilots use both hands, then it is a big difference.

There's a reason the handles are "out of phase" -- so you can apply maximum force with two pilots.

It becomes complicated to apply maximum force with two pilots, when (at least) one of them needs to be pulling on the control column pretty hard . . .

PW100 wrote:

7BOEING7 wrote:

smartplane wrote:

If it's impossible to turn, unless both pilots use both hands, then it is a big difference.

There's a reason the handles are "out of phase" -- so you can apply maximum force with two pilots.

It becomes complicated to apply maximum force with two pilots, when (at least) one of them needs to be pulling on the control column pretty hard . . .

When maximum force is needed, they also need to relax the column to reduce loads so it works out well. I'm being only slightly sarcastic.

planecane wrote:

14ccKemiskt wrote:

MrBretz wrote:

Here is a new article about the 737 MAX and MCAS.

https://www.nytimes.com/2019/06/01/busi ... crash.html

The point that was new to me was that Boeing discovered they could have low speed stalls as well as the high speed stalls that have been talked about. So they could not use a g force sensor and AoA to determine when MCAS kicked in. And, as everyone knows, they only used one AoA sensor assuming pilots could get them out of situations.

Great article by The New York Times. But it also fails to explain why MCAS wasn't reliant on both AoA sensors.

Only explanation I've seen on why the second sensor was not connected to MCAS comes from 60 minutes Australia. They claim that a Boeing whistleblower said that had the second sensor been used by MCAS, then the system would have been considered a "two sensor-system" which by definition would have required more thourough review by the FAA. Please let us hope that this is not the reason behind the single sensor "solution". If true, it would be disastrous for Boeing.

That makes no sense. Why would a more redundant system cause them to fear a more thorough review and why would the FAA review single sensor systems less thoroughly?

What is more likely is STS only used one AoA sensor so MCAS only used one sensor.

Or will discovery reveal the FAA had already told Boeing it was uncomfortable with the NG iteration, and the MAX was a 'bridge too far', approved on the basis of minimum / no flight characteristic changes (compared to the NG), and absolutely no future derivative? Then testing revealed changes were needed, and.................

Sounds complicated. No wonder the CEO was only promising the planes would be back in the air before the end of the year. Even that may be optimistic. Boeing have gone from trying to hide things from people to everything coming out in to the open. That's going to make finding a satisfactory solution for all the issues very tough for them now.

The mistakes made in design may have given Boeing a short term gain but they've created huge long term pain

I also agree with the post above - is there any real point trying to put blame onto the pilots any more? Can we move on from that now?

Emirates Tim Clark predicts that the B737MAX won't fly until after the Christmas

Link: https://www.arabianbusiness.com/transpo ... -christmas

xwb777 wrote:

Emirates Tim Clark predicts that the B737MAX won't fly until after the Christmas

Link: https://www.arabianbusiness.com/transpo ... -christmas

The longer it takes, the better it will be.

The worst thing Boeing could do is rush and make the same mistake twice.

In this day and age, the quarterly report will always take priority...So I'd hardly be surprised if it's the latter.

KFLLCFII wrote:

xwb777 wrote:

Emirates Tim Clark predicts that the B737MAX won't fly until after the Christmas

Link: https://www.arabianbusiness.com/transpo ... -christmas

The longer it takes, the better it will be.

The worst thing Boeing could do is rush and make the same mistake twice.

In this day and age, the quarterly report will always take priority...So I'd hardly be surprised if it's the latter.

Does extended time mean a more robust fix? Or just red tape and skepticism in getting it re-certified?

smokeybandit wrote:

KFLLCFII wrote:

xwb777 wrote:

Emirates Tim Clark predicts that the B737MAX won't fly until after the Christmas

Link: https://www.arabianbusiness.com/transpo ... -christmas

The longer it takes, the better it will be.

The worst thing Boeing could do is rush and make the same mistake twice.

In this day and age, the quarterly report will always take priority...So I'd hardly be surprised if it's the latter.

Does extended time mean a more robust fix? Or just red tape and skepticism in getting it re-certified?

Ironically, Boeing is facing almost the same problem as pilots of crashed flights. There is something crazy going on, they lost control of events, and there is no understanding of where to go, as too many things are going on. A lot of deer in headlights looks both in c-suit and engineering offices I presume.
Hopefully an outcome will be a bit better, though.

kalvado wrote:

smokeybandit wrote:

KFLLCFII wrote:

The longer it takes, the better it will be.

The worst thing Boeing could do is rush and make the same mistake twice.

In this day and age, the quarterly report will always take priority...So I'd hardly be surprised if it's the latter.

Does extended time mean a more robust fix? Or just red tape and skepticism in getting it re-certified?

Ironically, Boeing is facing almost the same problem as pilots of crashed flights. There is something crazy going on, they lost control of events, and there is no understanding of where to go, as too many things are going on. A lot of deer in headlights looks both in c-suit and engineering offices I presume.
Hopefully an outcome will be a bit better, though.

i think the Industry's big problem is how complex these machine are getting or how little one person knows about the whole design.

There needs to be CZAR's who are in charge of the design - who have flight and engineering experience - Not an MBA - who have the ability to say - wait a second - this isn't right. The buck stops with them - not in some committee or email chain.

Where are the Kelly Johnson's of today? He wasn't a Pilot but was a flight test engineer so he had a pretty good idea of how things worked.

morrisond wrote:

kalvado wrote:

smokeybandit wrote:

Does extended time mean a more robust fix? Or just red tape and skepticism in getting it re-certified?

Ironically, Boeing is facing almost the same problem as pilots of crashed flights. There is something crazy going on, they lost control of events, and there is no understanding of where to go, as too many things are going on. A lot of deer in headlights looks both in c-suit and engineering offices I presume.
Hopefully an outcome will be a bit better, though.

i think the Industry's big problem is how complex these machine are getting or how little one person knows about the whole design.

There needs to be CZAR's who are in charge of the design - who have flight and engineering experience - Not an MBA - who have the ability to say - wait a second - this isn't right. The buck stops with them - not in some committee or email chain.

Where are the Kelly Johnson's of today? He wasn't a Pilot but was a flight test engineer so he had a pretty good idea of how things worked.

Big part of a problem that Boeing seemingly had too much isolation between different teams. It doesn't take project csar to have more communication between teams, just a layer of people with wider scope and responsibility on things matching up within their area. A simple concept which should be understandable to an average MBA.
Now the scary part everyone says 777X is not affected by those issues. Will we get another lemon in the sky?

A late change, and fatal flaws, in a Boeing jet design

https://www.seattletimes.com/nation-wor ... et-design/

So originally MCAS was designed to use two sensors, two different sensors. AoA and g-force.

Reading this article, assuming that it is a true representation of what happened around MCAS, one could believe that rank amateurs are working at Boeing on safety critical issues. I hope this mess at Boeing gets cleared up, because how can on trust system ever again with safety relevant decisions?

And according to the information in this article, one has to call MCAS a stall avoidance system.

XRAYretired wrote:

Again, 6 months seems OK to me, especially that maybe two months of that is flight testing.

So how come Boeing on March 11th said that it was ready to be installed in the coming weeks and the FAA AD would be "no later than April" - https://boeing.mediaroom.com/news-relea ... tem=130402 Clearly at the time Boeing thought 4 months was completely reasonable and doable, indeed previous to march media was reporting that it had been delayed by the US Government shutdown, so if true, we're now at double what Boeing was expecting.

Six months might be reasonable, but if it was, then Boeing should have been telling people that up front, not 3 months, 4, 5, 6 etc. depending on the whim.

JibberJim wrote:

XRAYretired wrote:

Again, 6 months seems OK to me, especially that maybe two months of that is flight testing.

So how come Boeing on March 11th said that it was ready to be installed in the coming weeks and the FAA AD would be "no later than April" - https://boeing.mediaroom.com/news-relea ... tem=130402 Clearly at the time Boeing thought 4 months was completely reasonable and doable, indeed previous to march media was reporting that it had been delayed by the US Government shutdown, so if true, we're now at double what Boeing was expecting.

Six months might be reasonable, but if it was, then Boeing should have been telling people that up front, not 3 months, 4, 5, 6 etc. depending on the whim.

A further delay was acrued due to a problem found with the flap system. It may have been identified as a result of verification of the MCAS change or a separate review convened due to the events. There may have been other problems found that we are not aware of.

Reason for the current delay? anybodies guess, but it may be related to the review of NNCs/Training with Boeing wanting to submit a whole change pack in one go and not have manual changes outstanding.

Boeing have no obligation to tell the public anything, as you have seen throughout. That they did is at their whim and they got it wrong so it is likely to make them clam up even more so. Reguators have no obligation to comply with Boeing time estimates nor pre-approve a change not yet submitted. Indignation will not change it.

Ray

JibberJim wrote:

XRAYretired wrote:

Again, 6 months seems OK to me, especially that maybe two months of that is flight testing.

So how come Boeing on March 11th said that it was ready to be installed in the coming weeks and the FAA AD would be "no later than April" - https://boeing.mediaroom.com/news-relea ... tem=130402 Clearly at the time Boeing thought 4 months was completely reasonable and doable, indeed previous to march media was reporting that it had been delayed by the US Government shutdown, so if true, we're now at double what Boeing was expecting.

Six months might be reasonable, but if it was, then Boeing should have been telling people that up front, not 3 months, 4, 5, 6 etc. depending on the whim.

I would suggest the deeper everything gets looked at (by Boeing and external parties) the worse what they are looking at becomes.

The quick software patch fix they were hoping to apply just isnt going to pass scrutiny

But Boeing have got so used to doing what suits them best they assumed they would be able to keep doing things their way rather than the safe and correct way

smokeybandit wrote:

KFLLCFII wrote:

xwb777 wrote:

Emirates Tim Clark predicts that the B737MAX won't fly until after the Christmas

Link: https://www.arabianbusiness.com/transpo ... -christmas

The longer it takes, the better it will be.

The worst thing Boeing could do is rush and make the same mistake twice.

In this day and age, the quarterly report will always take priority...So I'd hardly be surprised if it's the latter.

Does extended time mean a more robust fix? Or just red tape and skepticism in getting it re-certified?

As major of a screw-up as it was, would either be a bad thing toward getting it right?

JibberJim wrote:

So how come Boeing on March 11th said that it was ready to be installed in the coming weeks and the FAA AD would be "no later than April" - https://boeing.mediaroom.com/news-relea ... tem=130402 Clearly at the time Boeing thought 4 months was completely reasonable and doable, indeed previous to march media was reporting that it had been delayed by the US Government shutdown, so if true, we're now at double what Boeing was expecting.

Because in march, Boeing had not yet understood that the world has changed and that taming the FAA will not be enough. They tarnished FAA reputation so badly that it may need several years before regaining that reputation, and the other regulators will be very carefull.

Olddog wrote:

JibberJim wrote:

So how come Boeing on March 11th said that it was ready to be installed in the coming weeks and the FAA AD would be "no later than April" - https://boeing.mediaroom.com/news-relea ... tem=130402 Clearly at the time Boeing thought 4 months was completely reasonable and doable, indeed previous to march media was reporting that it had been delayed by the US Government shutdown, so if true, we're now at double what Boeing was expecting.

Because in march, Boeing had not yet understood that the world has changed and that taming the FAA will not be enough. They tarnished FAA reputation so badly that it may need several years before regaining that reputation, and the other regulators will be very carefull.

Yes not only have Boeing messed up in advance of these crashes - their PR and communication since the crashes has appeared very haphazard and poor

I feel they've made this situation worse rather than better the way they have handled it. The CEO has been particularly unimpressive

Interested wrote:

Olddog wrote:

JibberJim wrote:

So how come Boeing on March 11th said that it was ready to be installed in the coming weeks and the FAA AD would be "no later than April" - https://boeing.mediaroom.com/news-relea ... tem=130402 Clearly at the time Boeing thought 4 months was completely reasonable and doable, indeed previous to march media was reporting that it had been delayed by the US Government shutdown, so if true, we're now at double what Boeing was expecting.

Because in march, Boeing had not yet understood that the world has changed and that taming the FAA will not be enough. They tarnished FAA reputation so badly that it may need several years before regaining that reputation, and the other regulators will be very carefull.

Yes not only have Boeing messed up in advance of these crashes - their PR and communication since the crashes has appeared very haphazard and poor

I feel they've made this situation worse rather than better the way they have handled it. The CEO has been particularly unimpressive

I have to fess up: I like Boeing. However, I was very disappointed when I heard the words “make a safe plane safer.” I believe with everyone watching now, the plane will be safer eventually. I just wished Boeing had “manned up”. Excuse me ladies.

MrBretz wrote:

Interested wrote:

Olddog wrote:

Because in march, Boeing had not yet understood that the world has changed and that taming the FAA will not be enough. They tarnished FAA reputation so badly that it may need several years before regaining that reputation, and the other regulators will be very carefull.

Yes not only have Boeing messed up in advance of these crashes - their PR and communication since the crashes has appeared very haphazard and poor

I feel they've made this situation worse rather than better the way they have handled it. The CEO has been particularly unimpressive

I have to fess up: I like Boeing. However, I was very disappointed when I heard the words “make a safe plane safer.” I believe with everyone watching now, the plane will be safer eventually. I just wished Boeing had “manned up”. Excuse me ladies.

At one stage they got some respect for me

The CEO said something like "we own this" but then they backtracked almost immediately

Just hold your hands up Boeing. Take it on the chin. No ifs or buts. You seriously messed up on lots of things here. Put it right. It's going to be the most expensive mistake in Boeing's history to put right. But do it well and do it with some class.

And earn the trust back

(Ps before these two crashes (especially before the second crash) I only had respect for the Boeing brand. I felt perfectly safe in their planes. Never doubted them for a second). Almost everything I've read on here and in the new since the second crash has just led me to not trust them and doubt them. I've been shocked to be honest

morrisond wrote:

i think the Industry's big problem is how complex these machine are getting or how little one person knows about the whole design.

No. The complexity is not the problem. The A320 use a far more complex horizontal stabilizer design and enjoy a far bigger reliability than the B737 horizontal stabilizer design. Do some search on Aviation Herald about "trim" and read the associated texts. I have do this since a week, and the difference is very clear. I did no identified a single incident involving an horizontal stabilizer runaway on a A320. The redundant control and monitor loop design make this event almost impossible. The very few cases where the electrical horizontal stabilizer failed, the pilots simply timed it with the hydraulic system operated from the trim wheels. No need for cutout switches, no need for high force on the wheels at some speed. I would prefer Boeing going in that direction instead of more pilot training for a failure mode specific to an obsolete design.

kalvado wrote:

Which makes some sense based on data; however assuming that basic skills would make MCAS outcomes different is a very far-reaching conclusion.

It's the opposite of far-fetched to assume that knowing how an airplane flies, knowing how your airplane operates, and knowing proper procedures to fly your airplane would have made a difference in safely flying a controllable airplane. Those are all basic skills that would have changed the outcome of these crashes.

MSPNWA wrote:

kalvado wrote:

Which makes some sense based on data; however assuming that basic skills would make MCAS outcomes different is a very far-reaching conclusion.

It's the opposite of far-fetched to assume that knowing how an airplane flies, knowing how your airplane operates, and knowing proper procedures to fly your airplane would have made a difference in safely flying a controllable airplane. Those are all basic skills that would have changed the outcome of these crashes.

Too bad unskilled design made those planes uncontrollable..

morrisond wrote:

Even if you want to pin it all on Boeing - and they are 100% the root cause of the crashes - do you seriously believe there was nothing the ET pilot's could have done better or should have done better with the proper training?

Mmm... I take the view that the designer is not the root cause but the entire cause of a crash where an aircraft tries to fly itself into the ground due to the failure of a single component (AoA indicator feeding false data to the MCAS system). How well the pilots concerned coped with a design fault that resulted in MCAS trying to kill all on board is of no importance to me.

IMO the MAX was badly designed and should not have been certified as safe to fly. IMO FAA has a lot to answer for.

Interested wrote:

MrBretz wrote:

Interested wrote:

Yes not only have Boeing messed up in advance of these crashes - their PR and communication since the crashes has appeared very haphazard and poor

I feel they've made this situation worse rather than better the way they have handled it. The CEO has been particularly unimpressive

I have to fess up: I like Boeing. However, I was very disappointed when I heard the words “make a safe plane safer.” I believe with everyone watching now, the plane will be safer eventually. I just wished Boeing had “manned up”. Excuse me ladies.

At one stage they got some respect for me

The CEO said something like "we own this" but then they backtracked almost immediately

Just hold your hands up Boeing. Take it on the chin. No ifs or buts. You seriously messed up on lots of things here. Put it right. It's going to be the most expensive mistake in Boeing's history to put right. But do it well and do it with some class.

And earn the trust back

(Ps before these two crashes (especially before the second crash) I only had respect for the Boeing brand. I felt perfectly safe in their planes. Never doubted them for a second). Almost everything I've read on here and in the new since the second crash has just led me to not trust them and doubt them. I've been shocked to be honest

I relate 100%. I felt incredibly safe in Boeing airplanes and went out of my way to book flights operated by Boeing aircraft. Not anymore.
Every day, a new article or revelation comes out regarding this MAX saga that completely erodes my trust in Boeing.

MSPNWA wrote:

kalvado wrote:

Which makes some sense based on data; however assuming that basic skills would make MCAS outcomes different is a very far-reaching conclusion.

It's the opposite of far-fetched to assume that knowing how an airplane flies, knowing how your airplane operates, and knowing proper procedures to fly your airplane would have made a difference in safely flying a controllable airplane. Those are all basic skills that would have changed the outcome of these crashes.

Extremely minor in the bigger picture of where we are all at now though

Aviation safety demands way higher standards of design and communication and safety BEFORE we even put pilots in charge of a plane

You know that

And all anyone does by trying to shift attention to pilots is cause others not to trust your motives or the motives of Boeing

It's making people feel worse about Boeing rather than better?

mjoelnir wrote:

A late change, and fatal flaws, in a Boeing jet design

https://www.seattletimes.com/nation-wor ... et-design/

So originally MCAS was designed to use two sensors, two different sensors. AoA and g-force.

Reading this article, assuming that it is a true representation of what happened around MCAS, one could believe that rank amateurs are working at Boeing on safety critical issues. I hope this mess at Boeing gets cleared up, because how can on trust system ever again with safety relevant decisions?

And according to the information in this article, one has to call MCAS a stall avoidance system.

Even though the original MCAS did rely on G-force sensors, along with an AoA sensor, why did they not incorporate both AoA sensors to MCAS even in the first iteration? I don't get it, there is no reasonable explanation to why you would not use two sensors when they were immediately available for use without extra cost. The fact that no-one considered the effects of the (single) sensor malfunctioning and tested what would happen if it did, is just a side effect of the single sensor implementation decision.

If I could influence the investigation of this affair, I would dig as deeply as possible into the underlying cause and decision process behind why the other AoA sensor was not connected to MCAS 1.0.

kalvado wrote:

Too bad unskilled design made those planes uncontrollable..

Stating a blatant, possibly intentional, inaccuracy about the facts of the crashes won't help your argument.

PixelFlight wrote:

morrisond wrote:

i think the Industry's big problem is how complex these machine are getting or how little one person knows about the whole design.

No. The complexity is not the problem. The A320 use a far more complex horizontal stabilizer design and enjoy a far bigger reliability than the B737 horizontal stabilizer design. Do some search on Aviation Herald about "trim" and read the associated texts. I have do this since a week, and the difference is very clear. I did no identified a single incident involving an horizontal stabilizer runaway on a A320. The redundant control and monitor loop design make this event almost impossible. The very few cases where the electrical horizontal stabilizer failed, the pilots simply timed it with the hydraulic system operated from the trim wheels. No need for cutout switches, no need for high force on the wheels at some speed. I would prefer Boeing going in that direction instead of more pilot training for a failure mode specific to an obsolete design.

You missed this one https://avherald.com/h?article=47d74074

If this had been ET302 at the same altitude when MCAS cut in - they would have ended up in the ground sooner than ET302. Note that the Trim didn't work on this either - although they had enough Elevator Authority to just keep it level - but it took them 4,000' to recover.

The pilots did a good job to recover. The knew where the Thrust levers were or it would have taken a lot longer to recover.

MSPNWA wrote:

kalvado wrote:

Too bad unskilled design made those planes uncontrollable..

Stating a blatant, possibly intentional, inaccuracy about the facts of the crashes won't help your argument.

You actually still think there is an argument going on?

Cant you just accept that this is all about the design and safety of these planes now. The pilots and passengers were just victims of a plane not safe enough to be flying?

Of course pilots will get some kind of updated and new training but BEFORE that happens there are going to be SIGNIFICANT improvements to the safety of these planes

Does it really matter to you to keep putting the focus on what the pilots attempted to do when faced with a system out of control ?

What are you trying to achieve?

morrisond wrote:

PixelFlight wrote:

morrisond wrote:

i think the Industry's big problem is how complex these machine are getting or how little one person knows about the whole design.

No. The complexity is not the problem. The A320 use a far more complex horizontal stabilizer design and enjoy a far bigger reliability than the B737 horizontal stabilizer design. Do some search on Aviation Herald about "trim" and read the associated texts. I have do this since a week, and the difference is very clear. I did no identified a single incident involving an horizontal stabilizer runaway on a A320. The redundant control and monitor loop design make this event almost impossible. The very few cases where the electrical horizontal stabilizer failed, the pilots simply timed it with the hydraulic system operated from the trim wheels. No need for cutout switches, no need for high force on the wheels at some speed. I would prefer Boeing going in that direction instead of more pilot training for a failure mode specific to an obsolete design.

You missed this one https://avherald.com/h?article=47d74074

If this had been ET302 at the same altitude when MCAS cut in - they would have ended up in the ground sooner than ET302. Note that the Trim didn't work on this either - although they had enough Elevator Authority to just keep it level - but it took them 4,000' to recover.

The pilots did a good job to recover. The knew where the Thrust levers were or it would have taken a lot longer to recover.

Same question - what's the point? What are you trying to achieve by talking about pilots all the time?

morrisond wrote:

PixelFlight wrote:

morrisond wrote:

i think the Industry's big problem is how complex these machine are getting or how little one person knows about the whole design.

No. The complexity is not the problem. The A320 use a far more complex horizontal stabilizer design and enjoy a far bigger reliability than the B737 horizontal stabilizer design. Do some search on Aviation Herald about "trim" and read the associated texts. I have do this since a week, and the difference is very clear. I did no identified a single incident involving an horizontal stabilizer runaway on a A320. The redundant control and monitor loop design make this event almost impossible. The very few cases where the electrical horizontal stabilizer failed, the pilots simply timed it with the hydraulic system operated from the trim wheels. No need for cutout switches, no need for high force on the wheels at some speed. I would prefer Boeing going in that direction instead of more pilot training for a failure mode specific to an obsolete design.

You missed this one https://avherald.com/h?article=47d74074

If this had been ET302 at the same altitude when MCAS cut in - they would have ended up in the ground sooner than ET302. Note that the Trim didn't work on this either - although they had enough Elevator Authority to just keep it level - but it took them 4,000' to recover.

The pilots did a good job to recover. The knew where the Thrust levers were or it would have taken a lot longer to recover.

I did not miss that one with _2_ frozen AoA sensors giving almost the same but wrong values. The loss of altitude was mainly caused by the 45 seconds delay before the pilots decided to apply a side stick correction. At lower altitude there would certainly have reacted more quickly. This unique event was 27 years after the introduction of the A320 aircraft family and did not harm anyone.