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PW100
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 1:37 pm

morrisond wrote:
Absynth wrote:
The people in this thread laying blame onto the pilots, should take a step back and have a long, hard look at the international safety standards for catastrophical failures. Which is less than one in a billion per flight hour. . . .


Isn't 1 billion divided by 250,000 equal to 4,000?

It doesn't matter how many times the vanes failed - the pilots still failed to follow procedures. It's about as silly as my ET has 50% of the pilot error fatal crashes (2 out of 4) in the last ten years with .5% of the worldwide fleet - a crash rate 100x the industry average.


Which procedure should they have followed?
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 1:40 pm

morrisond wrote:
xmp125a wrote:
sgbroimp wrote:
Now the question is, who is to blame here. My purely personal opinion is, that 90% boeing and 10% the pilots.


I'm not going to disagree with you on the Pilot's part in either crash - however I would add ET training for 40% on ET302 - Lionair 90% Boeing - 10% Pilots, ET302 - Boeing 50%, ET Training 40% - Pilots 10% (For leaving the Autothrotle in TOGA the whole flight). ET training - for their seemingly lack of focus on hand flying skills and quite possibly not even getting the MCAS procedure to there Pilots - or if they did in such an offhand manner it was basically useless.

I can't believe the ET pilots would have missed that much if they had been properly trained on the new MCAS procedure in the FCOM. It should have been top of mind and they should have had a copy in the cockpit.


Blame is 100% Boeing.

Training is a 100% Boeing problem too. There is no MCAS procedure you can train. Boeing assumed that pilots would use the runaway trim procedure, that is a death trap by itself.
The MAX simulators, Ethiopian has one, were sabotaged by Boeing, to be able to keep hiding MCAS, from operators and pilots.

Plain speaking, Boeing produced a death trap. You do not design a frame that puts passengers and crew completely unnecessary into danger.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 1:43 pm

GalaxyFlyer wrote:
mjoelnir wrote:
GalaxyFlyer wrote:
Standard procedure of flying the plane—apply trim to maintain neutral stock force. Yoke gets heavy as the trim inputs are made, counter with manual electric trim with the readily thumbed switches. Not a procedure—it’s called flying. Also, PULL THE POWER BACK. If you have no other means of controlling speed, leaving the power at TOGA is not helping. The problems only get worse with speed.

It wasn’t the pilots that crashed to planes, but they could have saved it.


Gf


Can you guaranty that manual electrical did work 100% in the Ethiopian crash? Do you have an explanation for why manual electrical trim stopped several times at the same angle, while trying to trim back from the MCAS action?

How about, does manual electrical trim really stop the movement commanded by MCAS?

I do not want to exclude the possibility that the pilots may have been able to stop the frame from crashing, but to declare that they were definitely able to refrain from crashing, is not yet supported by the evidence available at this time.


The stab moved every time their was commanded input. Stopped at 2.3 units very well could have been caused by the trim motor being overtorqued trying to overcome the pilot’s elevator input. I’d fault the pilots more for not pulling back the thrust at this point. Speed wasn’t gonna help them.

GF


The main point to controlling speed is pitch. If you can not correct pitch, you can not control speed.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 1:49 pm

Interested wrote:
mjoelnir wrote:
The big question for me is, if a serious safety revue is done, will that impact the NG too?

The standard run away procedure, cutting switches and trimming with the wheels, seems not to work on the MAX if the trim is already substantially away from normal.
It should be the same situation for the NG. Was the recovery procedure for runaway trim never revisited in any safety analysis in the last 30 years? Not at the move from classic to NG and now at the move from NG to MAX?
Does there have to be a review of the manual trim for all 737 still in operation?


But at least we know with NG the amount of times pilots have ever needed to do this is so low and the challenges when they do so manageable that it's not got to that catastrophic risk concern

Even better if those pilots for NG are trained more for coping if it ever did happen

Isn't the challenge for Max making sure the chances of the training being needed are at same level as NG and that when it happens the risks of catastrophe are at same level as NG

It's the new risks Max 737 has brought in that have caused these crashes. Risks we need to eliminate.


Yes, a trim runaway is that rare on the NG, that a not working manual trim as the last line of defense is never needed. But does that make it OK, that manual trim is not working in an seriously out of trim situation?
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 1:52 pm

GalaxyFlyer wrote:
Standard procedure of flying the plane—apply trim to maintain neutral stock force. Yoke gets heavy as the trim inputs are made, counter with manual electric trim with the readily thumbed switches. Not a procedure—it’s called flying. Also, PULL THE POWER BACK. If you have no other means of controlling speed, leaving the power at TOGA is not helping. The problems only get worse with speed.

It wasn’t the pilots that crashed to planes, but they could have saved it.
Gf


Except, that they were applying trim. And the FDR data clearly shows they DID understand how to use the electrical thump trim to balance the control column in pitch. So clearly, they DID KNOW how to fly. I('m at total loss why you feel the need to suggest otherwise . . .

Biggest question is, why did the uptrim repeatedly not go beyond 2.3 units stabalizer angle. If you study the FDR charts and (limited) CVR quotes in the prelim repport, the picture suggests that was not crew intention.

It is by no means clear what the pilots should have done to save the plane.

I agree on the power thing. Why did they not pull the power back? Were they affraid of the pitch down moment caused by reducing power, at a time when they needed most- if not all - of their physical strength to keep the nose abov ethe horizon? I don't know, do you?
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morrisond
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 1:55 pm

mjoelnir wrote:
morrisond wrote:
xmp125a wrote:


I'm not going to disagree with you on the Pilot's part in either crash - however I would add ET training for 40% on ET302 - Lionair 90% Boeing - 10% Pilots, ET302 - Boeing 50%, ET Training 40% - Pilots 10% (For leaving the Autothrotle in TOGA the whole flight). ET training - for their seemingly lack of focus on hand flying skills and quite possibly not even getting the MCAS procedure to there Pilots - or if they did in such an offhand manner it was basically useless.

I can't believe the ET pilots would have missed that much if they had been properly trained on the new MCAS procedure in the FCOM. It should have been top of mind and they should have had a copy in the cockpit.


Blame is 100% Boeing.

Training is a 100% Boeing problem too. There is no MCAS procedure you can train. Boeing assumed that pilots would use the runaway trim procedure, that is a death trap by itself.
The MAX simulators, Ethiopian has one, were sabotaged by Boeing, to be able to keep hiding MCAS, from operators and pilots.

Plain speaking, Boeing produced a death trap. You do not design a frame that puts passengers and crew completely unnecessary into danger.


I guess you never read the Ethiopian FCOM supplement that outlines the procedure that would have saved them from the back of the preliminary crash report. Or did Boeing and the CIA insert that into the report without the knowledge of ET Airlines or the ET Civil Aviation Authority? - Pages 32-33

https://leehamnews.com/wp-content/uploa ... ET-AVJ.pdf
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 1:55 pm

DenverTed wrote:
Taking the hypothetical that JT and ET were US airlines, don't you think they would have been grounded based on flying unairworthy planes and not reporting problems, or, problems with training being exposed by poor flying? So who's putting profit ahead of safety now, or the convenience of having a functioning air system over safety? Obviously there is a balance, but as long as JT and ET are flying, I'm not sure grounding the MAX for the busy summer season makes sense. Especially in the context of the world's agencies trying to create a global consensus on safety.


Flying unairworthy planes? Not reporting problems? Has any of that been confirmed somewhere? Shirley, I must have missed something . . .
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morrisond
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 1:57 pm

mjoelnir wrote:
GalaxyFlyer wrote:
mjoelnir wrote:

Can you guaranty that manual electrical did work 100% in the Ethiopian crash? Do you have an explanation for why manual electrical trim stopped several times at the same angle, while trying to trim back from the MCAS action?

How about, does manual electrical trim really stop the movement commanded by MCAS?

I do not want to exclude the possibility that the pilots may have been able to stop the frame from crashing, but to declare that they were definitely able to refrain from crashing, is not yet supported by the evidence available at this time.


The stab moved every time their was commanded input. Stopped at 2.3 units very well could have been caused by the trim motor being overtorqued trying to overcome the pilot’s elevator input. I’d fault the pilots more for not pulling back the thrust at this point. Speed wasn’t gonna help them.

GF


The main point to controlling speed is pitch. If you can not correct pitch, you can not control speed.


Yes - but it is a lot easier to control pitch if the Thrust isn't set at TOGA and all that thrust is flowing over your control surfaces.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 2:01 pm

morrisond wrote:
On the other hand People shouldn't be allowed to post unless they fully realize what went on.

. . .

I only respond when people keep insisting that Pilots were not a contributing factor. They were.


Great contradiction in one single post.
How can you say they were a contributing factor, if we don't understand their actions? It's really mind boggling.

I just wished the "declining pilot standard worldwide/poorly trained third world pilots camp" on here would take some of you own advice . . . .
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 2:08 pm

OldAeroGuy wrote:
chiad wrote:
I haven' read all the posts here so I don't know if anyone has linked this already about "Could US pilots have saved the 737 MAX8 ?"
https://www.youtube.com/watch?v=ZtHBz2-YpWE


Thanks, but already posted.

Of course, the simulation starts with the horizontal stabilizer electric motor switched off with the airplane out of trim.

It would be interesting to see what would have happened if the simulation started with the airplane trimmed before switching off the stab motor.


why would you try to correct the trim at a point where the trim is not incorrect.

the trim wheel needs to work properly if the trim is wrong
thats the mission
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 2:23 pm

PW100 wrote:
DenverTed wrote:
Taking the hypothetical that JT and ET were US airlines, don't you think they would have been grounded based on flying unairworthy planes and not reporting problems, or, problems with training being exposed by poor flying? So who's putting profit ahead of safety now, or the convenience of having a functioning air system over safety? Obviously there is a balance, but as long as JT and ET are flying, I'm not sure grounding the MAX for the busy summer season makes sense. Especially in the context of the world's agencies trying to create a global consensus on safety.


Flying unairworthy planes? Not reporting problems? Has any of that been confirmed somewhere? Shirley, I must have missed something . . .


See the original maintenance log entries on the JT flight prior to the mishap flight. Pilots didn’t come close to relaying the actual event in the log. Nothing known about ET.

GF
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 2:25 pm

mjoelnir wrote:
GalaxyFlyer wrote:
Standard procedure of flying the plane—apply trim to maintain neutral stock force. Yoke gets heavy as the trim inputs are made, counter with manual electric trim with the readily thumbed switches. Not a procedure—it’s called flying. Also, PULL THE POWER BACK. If you have no other means of controlling speed, leaving the power at TOGA is not helping. The problems only get worse with speed.

It wasn’t the pilots that crashed to planes, but they could have saved it.


Can you guaranty that manual electrical did work 100% in the Ethiopian crash? Do you have an explanation for why manual electrical trim stopped several times at the same angle, while trying to trim back from the MCAS action?

How about, does manual electrical trim really stop the movement commanded by MCAS?

I do not want to exclude the possibility that the pilots may have been able to stop the frame from crashing, but to declare that they were definitely able to refrain from crashing, is not yet supported by the evidence available at this time.


An important difference between MAX and earlier 737 versions is, that on earlier versions automatic trimming (be it STS, Mach Trim, autopilot, whatever), automatic trimming is stopped when an opposite movement is made on the control column. Which makes sense: if the auto systems are commanding nose down, and the crew want to go nose-up by pulling on the yoke, it makes sense to stop the opposite trimming.

However with the introduction of MCAS, as a "safety" "feel-enhancement" system, that is now no longer the case. Some auto trimming is still stopped by control column movement, but some auto trimming is not (MCAS). This introduces a complete new level of complications in auto trimming behaviour, and associated misunderstanding by existing 737 pilots.

Is this clearly explained in the 90 minutes iPad conversion course? Probably not, since MCAS was not part of that course. One would expect that something like this, which goes every natural 737 pilot feeling should be explained (and trained . . . !) thoroughly.
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GalaxyFlyer
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 2:27 pm

PW100 wrote:
GalaxyFlyer wrote:
Standard procedure of flying the plane—apply trim to maintain neutral stock force. Yoke gets heavy as the trim inputs are made, counter with manual electric trim with the readily thumbed switches. Not a procedure—it’s called flying. Also, PULL THE POWER BACK. If you have no other means of controlling speed, leaving the power at TOGA is not helping. The problems only get worse with speed.

It wasn’t the pilots that crashed to planes, but they could have saved it.
Gf


Except, that they were applying trim. And the FDR data clearly shows they DID understand how to use the electrical thump trim to balance the control column in pitch. So clearly, they DID KNOW how to fly. I('m at total loss why you feel the need to suggest otherwise . . .

Biggest question is, why did the uptrim repeatedly not go beyond 2.3 units stabalizer angle. If you study the FDR charts and (limited) CVR quotes in the prelim repport, the picture suggests that was not crew intention.

It is by no means clear what the pilots should have done to save the plane.

I agree on the power thing. Why did they not pull the power back? Were they affraid of the pitch down moment caused by reducing power, at a time when they needed most- if not all - of their physical strength to keep the nose abov ethe horizon? I don't know, do you?


Look at 05:40:00 to 05:40:30. The elevator aft stick inputs rapidly increase at the same time MCAS starts trimming. The pilots counter with two ANU inputs but the increasing back pressure jams the jackscrew which cannot move the stab against the increasing aerodynamic loads. The plane is at Vmo now when it should be at about 220 KIAS. Instead of countering the AND trim with ANU man electric, they hauled back on the yoke loading the jackscrew. Not saying that isn’t a natural instinct, but controlling speed was necessary.

GF
Last edited by GalaxyFlyer on Thu May 30, 2019 2:33 pm, edited 1 time in total.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 2:30 pm

PW100 wrote:
mjoelnir wrote:
GalaxyFlyer wrote:
Standard procedure of flying the plane—apply trim to maintain neutral stock force. Yoke gets heavy as the trim inputs are made, counter with manual electric trim with the readily thumbed switches. Not a procedure—it’s called flying. Also, PULL THE POWER BACK. If you have no other means of controlling speed, leaving the power at TOGA is not helping. The problems only get worse with speed.

It wasn’t the pilots that crashed to planes, but they could have saved it.


Can you guaranty that manual electrical did work 100% in the Ethiopian crash? Do you have an explanation for why manual electrical trim stopped several times at the same angle, while trying to trim back from the MCAS action?

How about, does manual electrical trim really stop the movement commanded by MCAS?

I do not want to exclude the possibility that the pilots may have been able to stop the frame from crashing, but to declare that they were definitely able to refrain from crashing, is not yet supported by the evidence available at this time.


An important difference between MAX and earlier 737 versions is, that on earlier versions automatic trimming (be it STS, Mach Trim, autopilot, whatever), automatic trimming is stopped when an opposite movement is made on the control column. Which makes sense: if the auto systems are commanding nose down, and the crew want to go nose-up by pulling on the yoke, it makes sense to stop the opposite trimming.

However with the introduction of MCAS, as a "safety" "feel-enhancement" system, that is now no longer the case. Some auto trimming is still stopped by control column movement, but some auto trimming is not (MCAS). This introduces a complete new level of complications in auto trimming behaviour, and associated misunderstanding by existing 737 pilots.

Is this clearly explained in the 90 minutes iPad conversion course? Probably not, since MCAS was not part of that course. One would expect that something like this, which goes every natural 737 pilot feeling should be explained (and trained . . . !) thoroughly.


Boeing introduced the trim brake back in the 707 era. The USAF never installed them until they lost a couple of tankers with runaway trim. Geilenkirchen was the last one in the ‘90s.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 2:34 pm

morrisond wrote:
xmp125a wrote:
sgbroimp wrote:
Now the question is, who is to blame here. My purely personal opinion is, that 90% boeing and 10% the pilots.


I'm not going to disagree with you on the Pilot's part in either crash - however I would add ET training for 40% on ET302 - Lionair 90% Boeing - 10% Pilots, ET302 - Boeing 50%, ET Training 40% - Pilots 10% (For leaving the Autothrotle in TOGA the whole flight). ET training - for their seemingly lack of focus on hand flying skills and quite possibly not even getting the MCAS procedure to there Pilots - or if they did in such an offhand manner it was basically useless.
.


Apparently, forgot your own advise . . . :

morrisond wrote:
On the other hand People shouldn't be allowed to post unless they fully realize what went on.
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 2:37 pm

Boeing CEO interview on CBS yesterday is a lesson in body language talk. He is shaking his head while trying to show emotion and doubling down on affirmative statements.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 2:58 pm

PW100 wrote:
mjoelnir wrote:
GalaxyFlyer wrote:
Standard procedure of flying the plane—apply trim to maintain neutral stock force. Yoke gets heavy as the trim inputs are made, counter with manual electric trim with the readily thumbed switches. Not a procedure—it’s called flying. Also, PULL THE POWER BACK. If you have no other means of controlling speed, leaving the power at TOGA is not helping. The problems only get worse with speed.

It wasn’t the pilots that crashed to planes, but they could have saved it.


Can you guaranty that manual electrical did work 100% in the Ethiopian crash? Do you have an explanation for why manual electrical trim stopped several times at the same angle, while trying to trim back from the MCAS action?

How about, does manual electrical trim really stop the movement commanded by MCAS?

I do not want to exclude the possibility that the pilots may have been able to stop the frame from crashing, but to declare that they were definitely able to refrain from crashing, is not yet supported by the evidence available at this time.


An important difference between MAX and earlier 737 versions is, that on earlier versions automatic trimming (be it STS, Mach Trim, autopilot, whatever), automatic trimming is stopped when an opposite movement is made on the control column. Which makes sense: if the auto systems are commanding nose down, and the crew want to go nose-up by pulling on the yoke, it makes sense to stop the opposite trimming.

However with the introduction of MCAS, as a "safety" "feel-enhancement" system, that is now no longer the case. Some auto trimming is still stopped by control column movement, but some auto trimming is not (MCAS). This introduces a complete new level of complications in auto trimming behaviour, and associated misunderstanding by existing 737 pilots.

Is this clearly explained in the 90 minutes iPad conversion course? Probably not, since MCAS was not part of that course. One would expect that something like this, which goes every natural 737 pilot feeling should be explained (and trained . . . !) thoroughly.


The issue is that when MCAS is working properly, it activates while the pilot is pulling back on the control column by design. If MCAS stopped trimming when the pilot made an opposite control column movement, it would never activate.

Your last sentence applies to Lion Air 100%. Even though some pilots were able to recognize a runaway trim on earlier flights, the crew of Lion Air 610 did not know anything about MCAS so I do not fault them for not recognizing the situation. The ET crew seemingly did recognize it but didn't appear to perform the runaway stabilizer NNC as intended.

I know you have a suspician that the electric trim was unable to continue trimming nose up because it stopped at 2.3 units each time. Without knowing exactly what the forces involved were and the power of the motor, we can't (as people on a.net) possibly determine if there was a mechanical limit introduced somehow. However, what is known from the FDR trace is that whenever there was a nose up trim command present the trim moved nose up. The points where it stopped at 2.3 units coincide with the command ceasing (either from releasing the thumb switch or moving the cutoff switches).

After the second MCAS nose down command, the trim was just about full nose down. I don't logically see why there would be MORE force required to trim up from 2.3 units with slightly less control column input being applied than it was from full nose down to 2.3 units. The movement from full nose down to 2.3 units was linear and didn't indicate the motor was struggling to move the trim. Also, I would assume that if the trim kept getting "stuck" at 2.3 units nose down, there would have been a mention by the pilot flying that it wasn't working. No such statement appeared during the time of the first two MCAS activations in the preliminary report. I would think that if such a statement was made, it would be considered pertinent by the investigators and included in the preliminary report.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 3:02 pm

https://www.bbc.co.uk/news/amp/business-48461110

The author of the Boeing 737 technical guide is saying he is confident the Ethiopia plane wouldn't have crashed had the disagree light been working.

He says it would have given an earlier indication to the pilots of what they were dealing with and what they needed to do

Interestingly Boeing CEO seems to be acknowledging this in the same article. I know it's not good for boeing to admit mistakes but PERHAPS a big part of getting the planes ungrounded relies on the indicator light making a difference to pilots understanding of the situation and what to do next

So it's better for Boeing to say this would help pilots save a plane than deny it. As they can make sure it's there in the future and help get the planes ungrounded?

Accept more blame now to allow the planes to fly again and get ungrounded?

Obviously the initial response when the disagree light issue came up was to claim it would have made no difference. Seems that approach is changing now everybody is getting an understanding of what happened and what's needed to get the plane flying again?

Makes me feel a bit cynical but I think that's what may be happening here. Accept some mistakes, take a hit on Ethiopia but get the planes back in the air sooner by saying the disagree light would have made a difference.
 
morrisond
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 3:09 pm

PW100 wrote:
morrisond wrote:
xmp125a wrote:


I'm not going to disagree with you on the Pilot's part in either crash - however I would add ET training for 40% on ET302 - Lionair 90% Boeing - 10% Pilots, ET302 - Boeing 50%, ET Training 40% - Pilots 10% (For leaving the Autothrotle in TOGA the whole flight). ET training - for their seemingly lack of focus on hand flying skills and quite possibly not even getting the MCAS procedure to there Pilots - or if they did in such an offhand manner it was basically useless.
.


Apparently, forgot your own advise . . . :

morrisond wrote:
On the other hand People shouldn't be allowed to post unless they fully realize what went on.


Nice - taking quotes totally out of context and reusing them. That was in response to poster implying that Boeing never gave Customers any information or procedures to deal with MCAS after Lionair. Now it's debatable how effective those procedures were - but they did give them to Airlines - they did not totally bury there heads in the sand and say there are no issues.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 3:10 pm

planecane wrote:
I know you have a suspician that the electric trim was unable to continue trimming nose up because it stopped at 2.3 units each time. Without knowing exactly what the forces involved were and the power of the motor, we can't (as people on a.net) possibly determine if there was a mechanical limit introduced somehow. However, what is known from the FDR trace is that whenever there was a nose up trim command present the trim moved nose up. The points where it stopped at 2.3 units coincide with the command ceasing (either from releasing the thumb switch or moving the cutoff switches).

After the second MCAS nose down command, the trim was just about full nose down. I don't logically see why there would be MORE force required to trim up from 2.3 units with slightly less control column input being applied than it was from full nose down to 2.3 units. The movement from full nose down to 2.3 units was linear and didn't indicate the motor was struggling to move the trim. Also, I would assume that if the trim kept getting "stuck" at 2.3 units nose down, there would have been a mention by the pilot flying that it wasn't working. No such statement appeared during the time of the first two MCAS activations in the preliminary report. I would think that if such a statement was made, it would be considered pertinent by the investigators and included in the preliminary report.

One can envision a few possible failures creating artificial stop.
Pure speculation below:
- at high force point, backup nut separated from the mount and prevented main nut going up the jackscrew acting as a lock nut.
- At high force, one of the nuts damaged jackscrew preventing other nut moving over that spot.

I can come up with a few more scenarios
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 3:22 pm

morrisond wrote:
xmp125a wrote:
sgbroimp wrote:
Now the question is, who is to blame here. My purely personal opinion is, that 90% boeing and 10% the pilots.


I'm not going to disagree with you on the Pilot's part in either crash .


So if you agree with the above isn't that substantial enough to stop worrying about the pilots actions and to focus on what Boeing need to do to stop pilots anywhere in the world facing a similar situation in the future

I think we all accept that huge mistakes in design and implementation and communication have been made by Boeing. The CEO has just apologised for what's happened again and acknowledged they need to regain trust etc. He's said it's going to be a gradual process.

Ive seen the head of the US pilots union saying it's inexcusable to blame the pilots for these crashes and saying shame on Boeing for do so. He's not head of the Ethiopian pilots union.

Ive just seen the guy who wrote the technical guide for Boeing 737s saying the flight would have been saved had the disagree light worked whilst the CEO of Boeing on same day accepts that was a mistake etc

Isn't that enough to just move on now and stop clutching at any kind of real blame for the pilots and just accept Boeing messed up and now lets get this sorted for future pilots and passengers

I said it weeks ago - I never want to be on a plane that ever needs these manual trim procedures using. They scare the life out of me. I can't believe they even exist in this day and age. So let's just get back to having planes that are designed so these trims are never needed. And when they are you can't die whilst pilots struggle to have to use them.

For sure Morrison if you want these guys trained to use the trim etc let's do it as well. But that's not the real issue here. The Max flawed design has led us to spend weeks analysing and dissecting the ins and outs of something we should never even need to be discussing.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 3:44 pm

I think Boeing is so deep in the muck now, some their own doing, some from the politics and negative press, that flight testing will have to be done with a 5 year old test pilot at the controls with the CEO on board for everyone to be convinced the Max is ready to go.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 3:48 pm

kalvado wrote:
planecane wrote:
I know you have a suspician that the electric trim was unable to continue trimming nose up because it stopped at 2.3 units each time. Without knowing exactly what the forces involved were and the power of the motor, we can't (as people on a.net) possibly determine if there was a mechanical limit introduced somehow. However, what is known from the FDR trace is that whenever there was a nose up trim command present the trim moved nose up. The points where it stopped at 2.3 units coincide with the command ceasing (either from releasing the thumb switch or moving the cutoff switches).

After the second MCAS nose down command, the trim was just about full nose down. I don't logically see why there would be MORE force required to trim up from 2.3 units with slightly less control column input being applied than it was from full nose down to 2.3 units. The movement from full nose down to 2.3 units was linear and didn't indicate the motor was struggling to move the trim. Also, I would assume that if the trim kept getting "stuck" at 2.3 units nose down, there would have been a mention by the pilot flying that it wasn't working. No such statement appeared during the time of the first two MCAS activations in the preliminary report. I would think that if such a statement was made, it would be considered pertinent by the investigators and included in the preliminary report.

One can envision a few possible failures creating artificial stop.
Pure speculation below:
- at high force point, backup nut separated from the mount and prevented main nut going up the jackscrew acting as a lock nut.
- At high force, one of the nuts damaged jackscrew preventing other nut moving over that spot.

I can come up with a few more scenarios


Those scenarios are definitely possible. Hopefully they have been able to analyze the jackscrew to determine if a physical failure did happen. I just think it would be a heck of a coincidence that they stopped pressing the switch or moved the cutout switches at the exact moment that the stabilizer was physically prevented from moving. It's not like there is force feedback on the thumb switch.
 
planecane
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 3:58 pm

Interested wrote:
morrisond wrote:
xmp125a wrote:


I'm not going to disagree with you on the Pilot's part in either crash .


So if you agree with the above isn't that substantial enough to stop worrying about the pilots actions and to focus on what Boeing need to do to stop pilots anywhere in the world facing a similar situation in the future

I think we all accept that huge mistakes in design and implementation and communication have been made by Boeing. The CEO has just apologised for what's happened again and acknowledged they need to regain trust etc. He's said it's going to be a gradual process.

Ive seen the head of the US pilots union saying it's inexcusable to blame the pilots for these crashes and saying shame on Boeing for do so. He's not head of the Ethiopian pilots union.

Ive just seen the guy who wrote the technical guide for Boeing 737s saying the flight would have been saved had the disagree light worked whilst the CEO of Boeing on same day accepts that was a mistake etc

Isn't that enough to just move on now and stop clutching at any kind of real blame for the pilots and just accept Boeing messed up and now lets get this sorted for future pilots and passengers

I said it weeks ago - I never want to be on a plane that ever needs these manual trim procedures using. They scare the life out of me. I can't believe they even exist in this day and age. So let's just get back to having planes that are designed so these trims are never needed. And when they are you can't die whilst pilots struggle to have to use them.

For sure Morrison if you want these guys trained to use the trim etc let's do it as well. But that's not the real issue here. The Max flawed design has led us to spend weeks analysing and dissecting the ins and outs of something we should never even need to be discussing.


The problem is that it is highly unlikely for a model that sells even a few hundred units and is in service long enough to never have a non-normal situation occur. While obviously, Boeing needs to fix whatever process led to MCAS being designed the way it was, we can't just brush off the pilot's actions. If I'm on a flight that experiences a 1 in a million or 1 in 10 million flights failure, I want (and expect) the pilots to be trained enough and skilled enough to be able to recover.

Even though it is unlikely (not impossible) to ever be needed, the A320 also has a manual trim wheel as the "last ditch backup" in the event of powered trim system failure.
 
kalvado
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 4:03 pm

planecane wrote:
kalvado wrote:
One can envision a few possible failures creating artificial stop.
Pure speculation below:
- at high force point, backup nut separated from the mount and prevented main nut going up the jackscrew acting as a lock nut.
- At high force, one of the nuts damaged jackscrew preventing other nut moving over that spot.

I can come up with a few more scenarios


Those scenarios are definitely possible. Hopefully they have been able to analyze the jackscrew to determine if a physical failure did happen. I just think it would be a heck of a coincidence that they stopped pressing the switch or moved the cutout switches at the exact moment that the stabilizer was physically prevented from moving. It's not like there is force feedback on the thumb switch.

In general, it would be a good idea to get an old 737 sitting in the desert and see what kind of loads can trim mechanism can take. May be another aspect of the situation...
I said it previously - I would be surprised if entire system is designed to handle loads much higher than manual drive. If manual drive got too heavy, electrical drive could be running at its limit as well, or mechanical parts could be working harder than they should.
 
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PixelFlight
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 4:15 pm

sgrow787 wrote:
I'm still not convinced it was a single-sensor design, mainly because (a) Boeing to date hasn't come out and stated it was a single-sensor design, (b) all the news articles to date have been careful to say "single sensor" in a way that is ambiguous, and (c) all we have to support single-sensor is some anonymous Boeing engineer stating it was a single-sensor design to get around a disagree scenario (ie indicator) to meet the no-new-training requirement.

(a) AD #: 2018-23-51 Unsafe Condition:
This AD was prompted by analysis performed by the manufacturer showing that if an
erroneously high single angle of attack (AOA) sensor input is received by the flight control system,
there is a potential for repeated nose-down trim commands of the horizontal stabilizer.

(b) How single sensor input is ambiguous ?

(c) Boeing PR about fixes: "Flight control system will now compare inputs from both AOA sensors." https://www.boeing.com/commercial/737max/737-max-software-updates.page

From Satcom Guru article :https://www.satcom.guru/2018/11/737-fcc-pitch-axis-augmentation-command.html
Active FCC CPU#1 commands are made based on a single sensor set. Active FCC CPU#2 raises an alert if the output command disagrees with the CPU#1 calculation, but does not stop CPU#1 command.
It appears CPU#2 is using the same sensor data as CPU#1, making it susceptible to a common failure, using the same valid but false data.
 
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PixelFlight
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 4:26 pm

barney captain wrote:
GalaxyFlyer wrote:
It wasn’t the pilots that crashed to planes, but they could have saved it.

As proven by the first two Lior Air crews.

False! :shakehead:
The "two Lior Air crews" did not saved the flight. An off-duty pilot did save JT043:
https://www.airliners.net/forum/viewtopic.php?f=3&t=1417519&hilit=ethiopian&start=3000#p21202709
 
Interested
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 4:32 pm

planecane wrote:
Interested wrote:
morrisond wrote:

I'm not going to disagree with you on the Pilot's part in either crash .


So if you agree with the above isn't that substantial enough to stop worrying about the pilots actions and to focus on what Boeing need to do to stop pilots anywhere in the world facing a similar situation in the future

I think we all accept that huge mistakes in design and implementation and communication have been made by Boeing. The CEO has just apologised for what's happened again and acknowledged they need to regain trust etc. He's said it's going to be a gradual process.

Ive seen the head of the US pilots union saying it's inexcusable to blame the pilots for these crashes and saying shame on Boeing for do so. He's not head of the Ethiopian pilots union.

Ive just seen the guy who wrote the technical guide for Boeing 737s saying the flight would have been saved had the disagree light worked whilst the CEO of Boeing on same day accepts that was a mistake etc

Isn't that enough to just move on now and stop clutching at any kind of real blame for the pilots and just accept Boeing messed up and now lets get this sorted for future pilots and passengers

I said it weeks ago - I never want to be on a plane that ever needs these manual trim procedures using. They scare the life out of me. I can't believe they even exist in this day and age. So let's just get back to having planes that are designed so these trims are never needed. And when they are you can't die whilst pilots struggle to have to use them.

For sure Morrison if you want these guys trained to use the trim etc let's do it as well. But that's not the real issue here. The Max flawed design has led us to spend weeks analysing and dissecting the ins and outs of something we should never even need to be discussing.


The problem is that it is highly unlikely for a model that sells even a few hundred units and is in service long enough to never have a non-normal situation occur. While obviously, Boeing needs to fix whatever process led to MCAS being designed the way it was, we can't just brush off the pilot's actions. If I'm on a flight that experiences a 1 in a million or 1 in 10 million flights failure, I want (and expect) the pilots to be trained enough and skilled enough to be able to recover.

Even though it is unlikely (not impossible) to ever be needed, the A320 also has a manual trim wheel as the "last ditch backup" in the event of powered trim system failure.


Would be really interesting to know how many times manual trim has had to be used on NG 737s. Not only that - how aggressive was the situation they were trying to rectify?

I guess in the past whenever it's had to be used its not been a time when the plane keeps trying to crash itself?

Anyone know?

I would also investigate any future flights that have to use manual trim but don't crash with the same attention to detail they give to planes that do crash. There must be so much tgat can be learnt from those flights.

I will add that there is probably as much to learn if not more to learn from what the pilots on the lion air plane that had issues but didn't crash and what they faced when things started going wrong for them.
 
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PixelFlight
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 4:40 pm

PW100 wrote:
An important difference between MAX and earlier 737 versions is, that on earlier versions automatic trimming (be it STS, Mach Trim, autopilot, whatever), automatic trimming is stopped when an opposite movement is made on the control column. Which makes sense: if the auto systems are commanding nose down, and the crew want to go nose-up by pulling on the yoke, it makes sense to stop the opposite trimming.

From that post about the STS and control column in the opposite direction:
https://www.pprune.org/tech-log/614997-b-737-speed-trim-system.html#post10300036
No, it will happily continue to trim even if you push (you need to) forward on the controls after take off when you accelerate. It will stop when you apply opposite trim. Which I do on every take off since STS trims the aircraft out of trim. It normally takes 2-3 turns of trim, depending on when you start to trim.
Weird system!

The difference between the STS and the MCAS is how there respective code can go wrong. There are some grey area about the STS as it can potentially send dangerous stab trim command too if it goes very erratic. Satcom Guru explained that STS (and MCAS) run on a single CPU on an single side FCC in manual flight mode. Could be an another certification issue for the 737 NG and 737 MAX now that the design is reviewed in detail...
 
planecane
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 4:41 pm

Interested wrote:
planecane wrote:
Interested wrote:

So if you agree with the above isn't that substantial enough to stop worrying about the pilots actions and to focus on what Boeing need to do to stop pilots anywhere in the world facing a similar situation in the future

I think we all accept that huge mistakes in design and implementation and communication have been made by Boeing. The CEO has just apologised for what's happened again and acknowledged they need to regain trust etc. He's said it's going to be a gradual process.

Ive seen the head of the US pilots union saying it's inexcusable to blame the pilots for these crashes and saying shame on Boeing for do so. He's not head of the Ethiopian pilots union.

Ive just seen the guy who wrote the technical guide for Boeing 737s saying the flight would have been saved had the disagree light worked whilst the CEO of Boeing on same day accepts that was a mistake etc

Isn't that enough to just move on now and stop clutching at any kind of real blame for the pilots and just accept Boeing messed up and now lets get this sorted for future pilots and passengers

I said it weeks ago - I never want to be on a plane that ever needs these manual trim procedures using. They scare the life out of me. I can't believe they even exist in this day and age. So let's just get back to having planes that are designed so these trims are never needed. And when they are you can't die whilst pilots struggle to have to use them.

For sure Morrison if you want these guys trained to use the trim etc let's do it as well. But that's not the real issue here. The Max flawed design has led us to spend weeks analysing and dissecting the ins and outs of something we should never even need to be discussing.


The problem is that it is highly unlikely for a model that sells even a few hundred units and is in service long enough to never have a non-normal situation occur. While obviously, Boeing needs to fix whatever process led to MCAS being designed the way it was, we can't just brush off the pilot's actions. If I'm on a flight that experiences a 1 in a million or 1 in 10 million flights failure, I want (and expect) the pilots to be trained enough and skilled enough to be able to recover.

Even though it is unlikely (not impossible) to ever be needed, the A320 also has a manual trim wheel as the "last ditch backup" in the event of powered trim system failure.


Would be really interesting to know how many times manual trim has had to be used on NG 737s. Not only that - how aggressive was the situation they were trying to rectify?

I guess in the past whenever it's had to be used its not been a time when the plane keeps trying to crash itself?

Anyone know?

I would also investigate any future flights that have to use manual trim but don't crash with the same attention to detail they give to planes that do crash. There must be so much tgat can be learnt from those flights.

I will add that there is probably as much to learn if not more to learn from what the pilots on the lion air plane that had issues but didn't crash and what they faced when things started going wrong for them.


It would be interesting to have that information. My guess is that any time the manual trim wheel has been used on the NG, it's been because the trim stopped functioning but they were starting pretty close to being in trim. I would assume that the wheel is not difficult to use when the aircraft is close to being in trim.

I'd also be curious when the last time was that there was a 737 runaway stabilizer pre-MCAS and how many times it has happened per million flights since the introduction of the classic series in 1984. My suspicion is that it is an incredibly rare event.
 
planecane
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 4:47 pm

PixelFlight wrote:
PW100 wrote:
An important difference between MAX and earlier 737 versions is, that on earlier versions automatic trimming (be it STS, Mach Trim, autopilot, whatever), automatic trimming is stopped when an opposite movement is made on the control column. Which makes sense: if the auto systems are commanding nose down, and the crew want to go nose-up by pulling on the yoke, it makes sense to stop the opposite trimming.

From that post about the STS and control column in the opposite direction:
https://www.pprune.org/tech-log/614997-b-737-speed-trim-system.html#post10300036
No, it will happily continue to trim even if you push (you need to) forward on the controls after take off when you accelerate. It will stop when you apply opposite trim. Which I do on every take off since STS trims the aircraft out of trim. It normally takes 2-3 turns of trim, depending on when you start to trim.
Weird system!

The difference between the STS and the MCAS is how there respective code can go wrong. There are some grey area about the STS as it can potentially send dangerous stab trim command too if it goes very erratic. Satcom Guru explained that STS (and MCAS) run on a single CPU on an single side FCC in manual flight mode. Could be an another certification issue for the 737 NG and 737 MAX now that the design is reviewed in detail...


I think that STS has proven itself not to be a problem. With 7000 NGs flying around for what has to be over 50 million flights, the fact that there hasn't been an STS related crash would seem to prove that it is not a safety issue.
 
Interested
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 4:55 pm

Did they use manual trim on the Lion air flight that didn't crash??
 
planecane
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 4:59 pm

Interested wrote:
Did they use manual trim on the Lion air flight that didn't crash??

That's a very good question. Since they cut off electric trim you have to assume they did. I can't imagine they flew 2 hours or whatever it was without trimming.
 
GalaxyFlyer
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 5:03 pm

Interested wrote:
morrisond wrote:
xmp125a wrote:


I'm not going to disagree with you on the Pilot's part in either crash .


So if you agree with the above isn't that substantial enough to stop worrying about the pilots actions and to focus on what Boeing need to do to stop pilots anywhere in the world facing a similar situation in the future

I think we all accept that huge mistakes in design and implementation and communication have been made by Boeing. The CEO has just apologised for what's happened again and acknowledged they need to regain trust etc. He's said it's going to be a gradual process.

Ive seen the head of the US pilots union saying it's inexcusable to blame the pilots for these crashes and saying shame on Boeing for do so. He's not head of the Ethiopian pilots union.

Ive just seen the guy who wrote the technical guide for Boeing 737s saying the flight would have been saved had the disagree light worked whilst the CEO of Boeing on same day accepts that was a mistake etc

Isn't that enough to just move on now and stop clutching at any kind of real blame for the pilots and just accept Boeing messed up and now lets get this sorted for future pilots and passengers

I said it weeks ago - I never want to be on a plane that ever needs these manual trim procedures using. They scare the life out of me. I can't believe they even exist in this day and age. So let's just get back to having planes that are designed so these trims are never needed. And when they are you can't die whilst pilots struggle to have to use them.

For sure Morrison if you want these guys trained to use the trim etc let's do it as well. But that's not the real issue here. The Max flawed design has led us to spend weeks analysing and dissecting the ins and outs of something we should never even need to be discussing.


How did you get on board any plane—they all have trimming systems. Boeing’s since the 707. Airbus uses software which is far more complex than cables and pulleys.

GF
 
ArgentoSystems
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 5:05 pm

Vladex wrote:
Boeing CEO interview on CBS yesterday is a lesson in body language talk. He is shaking his head while trying to show emotion and doubling down on affirmative statements.


Lol.

Norah O'Donnell: You'd put your family on a 737 Max?

Dennis Muilenburg: [shaking head repeatedly] Without any hesitation. Absolutely.
 
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PixelFlight
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 5:11 pm

planecane wrote:
PixelFlight wrote:
PW100 wrote:
An important difference between MAX and earlier 737 versions is, that on earlier versions automatic trimming (be it STS, Mach Trim, autopilot, whatever), automatic trimming is stopped when an opposite movement is made on the control column. Which makes sense: if the auto systems are commanding nose down, and the crew want to go nose-up by pulling on the yoke, it makes sense to stop the opposite trimming.

From that post about the STS and control column in the opposite direction:
https://www.pprune.org/tech-log/614997-b-737-speed-trim-system.html#post10300036
No, it will happily continue to trim even if you push (you need to) forward on the controls after take off when you accelerate. It will stop when you apply opposite trim. Which I do on every take off since STS trims the aircraft out of trim. It normally takes 2-3 turns of trim, depending on when you start to trim.
Weird system!

The difference between the STS and the MCAS is how there respective code can go wrong. There are some grey area about the STS as it can potentially send dangerous stab trim command too if it goes very erratic. Satcom Guru explained that STS (and MCAS) run on a single CPU on an single side FCC in manual flight mode. Could be an another certification issue for the 737 NG and 737 MAX now that the design is reviewed in detail...


I think that STS has proven itself not to be a problem. With 7000 NGs flying around for what has to be over 50 million flights, the fact that there hasn't been an STS related crash would seem to prove that it is not a safety issue.

It's not the STS itself that will make the certification !
The fact is that the STS and the MCAS share exactly the same safety context in there computing implementation. If the new MCAS detailed safety analysis found something risky in that safety context, the STS will automatically be affected too. From the safety assessment and safety certification point of view this could be an issue given the scale of the current crisis. There now have to be so paranoid about safety that it would be very difficult to justify a deviation, even if no accident could yet be linked to that deviation. Imagine that something go wrong in the future and that it was deliberately avoided in the actual detailed safety analysis. Boeing and FAA are under international pressure to deliver an impeccable analysis. Not the best time to avoid a possible safety issue, even if it will require a software update to the 737 NG too.
 
mjoelnir
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 5:13 pm

morrisond wrote:
PW100 wrote:
morrisond wrote:

I'm not going to disagree with you on the Pilot's part in either crash - however I would add ET training for 40% on ET302 - Lionair 90% Boeing - 10% Pilots, ET302 - Boeing 50%, ET Training 40% - Pilots 10% (For leaving the Autothrotle in TOGA the whole flight). ET training - for their seemingly lack of focus on hand flying skills and quite possibly not even getting the MCAS procedure to there Pilots - or if they did in such an offhand manner it was basically useless.
.


Apparently, forgot your own advise . . . :

morrisond wrote:
On the other hand People shouldn't be allowed to post unless they fully realize what went on.


Nice - taking quotes totally out of context and reusing them. That was in response to poster implying that Boeing never gave Customers any information or procedures to deal with MCAS after Lionair. Now it's debatable how effective those procedures were - but they did give them to Airlines - they did not totally bury there heads in the sand and say there are no issues.


Boeing did practical nothing. They did not explain how MCAS functioned. They did not give out how you recognize and train for MCAS failure mode. They did not fix the simulators so they would show how MCAS works and how it behaves with an AoA failure.
Boeing just pointed to the runaway trim procedure.
Boeing even kept quite over the non existence of the light declaring AoA disagree, pointing exactly at the situation that could produce a MCAS going amok situation. Even if this light should have been a standard feature and being described in the manual.

It is astonishing how you want to leave Boeing of the hook and accuse everybody else.
 
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PixelFlight
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 5:18 pm

Interested wrote:
Did they use manual trim on the Lion air flight that didn't crash??

Yes JT043 did use manual trim wheels. You can see the PITCH TRIM POSITION changes of the FDR traces of the JT610 preliminary report while no TRIM MANUAL nor TRIM AUTOMATIC signals exists.
The same document contain this about "PK-LQP Previous Flight" (JT043):
At 14:28:28 UTC, the PIC moved the STAB TRIM switches to CUT OUT. The PIC
re-engaged the STAB TRIM switches to NORMAL, but almost immediately the
problem re-appeared. The PIC then moved the STAB TRIM switches back to CUT
OUT and continued with manual trim without auto-pilot until the end of the flight.
 
Interested
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 5:18 pm

planecane wrote:
Interested wrote:
Did they use manual trim on the Lion air flight that didn't crash??

That's a very good question. Since they cut off electric trim you have to assume they did. I can't imagine they flew 2 hours or whatever it was without trimming.


Well if they did and it's as rare an occurrence as people say it is then I'm staggered that the plane gets to fly the next day with passengers on it?

Surely certain failings on a plane warrant a grounding and because this was so rare it should qualify

Should certainly qualify in the future?

Not much between a disaster and a safe flight other than a jump seat pilot?

Yet look how the two occurrence get treated so differently just because the first plane landed safely in the end?
 
XRAYretired
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 5:27 pm

Interested wrote:
https://www.bbc.co.uk/news/amp/business-48461110

The author of the Boeing 737 technical guide is saying he is confident the Ethiopia plane wouldn't have crashed had the disagree light been working.

He says it would have given an earlier indication to the pilots of what they were dealing with and what they needed to do

Interestingly Boeing CEO seems to be acknowledging this in the same article. I know it's not good for boeing to admit mistakes but PERHAPS a big part of getting the planes ungrounded relies on the indicator light making a difference to pilots understanding of the situation and what to do next

So it's better for Boeing to say this would help pilots save a plane than deny it. As they can make sure it's there in the future and help get the planes ungrounded?

Accept more blame now to allow the planes to fly again and get ungrounded?

Obviously the initial response when the disagree light issue came up was to claim it would have made no difference. Seems that approach is changing now everybody is getting an understanding of what happened and what's needed to get the plane flying again?

Makes me feel a bit cynical but I think that's what may be happening here. Accept some mistakes, take a hit on Ethiopia but get the planes back in the air sooner by saying the disagree light would have made a difference.

Brave chap, Chris Brady. I got abuse for only suggesting that AOA Disagree could have made a difference just on this forum.

At least Boeing CEO seems to have struck the right tone at last.


Ray
 
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7BOEING7
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 6:12 pm

XRAYretired wrote:
Interested wrote:
https://www.bbc.co.uk/news/amp/business-48461110

The author of the Boeing 737 technical guide is saying he is confident the Ethiopia plane wouldn't have crashed had the disagree light been working.

He says it would have given an earlier indication to the pilots of what they were dealing with and what they needed to do

Interestingly Boeing CEO seems to be acknowledging this in the same article. I know it's not good for boeing to admit mistakes but PERHAPS a big part of getting the planes ungrounded relies on the indicator light making a difference to pilots understanding of the situation and what to do next

So it's better for Boeing to say this would help pilots save a plane than deny it. As they can make sure it's there in the future and help get the planes ungrounded?

Accept more blame now to allow the planes to fly again and get ungrounded?

Obviously the initial response when the disagree light issue came up was to claim it would have made no difference. Seems that approach is changing now everybody is getting an understanding of what happened and what's needed to get the plane flying again?

Makes me feel a bit cynical but I think that's what may be happening here. Accept some mistakes, take a hit on Ethiopia but get the planes back in the air sooner by saying the disagree light would have made a difference.

Brave chap, Chris Brady. I got abuse for only suggesting that AOA Disagree could have made a difference just on this forum.

At least Boeing CEO seems to have struck the right tone at last.


Ray


The Boeing CEO admitted the omission of the AOA DISAGREE message was a mistake not that it would have saved the flight -- which it wouldn't have.

With the IAS DISAGREE alert staring the captain in the face (probably more visible to him than the AOA DISAGREE would have been), if the ET crew had been more familiar with the bulletin and managed the thrust properly, that could have saved the flight.
 
planecane
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 6:16 pm

Interested wrote:
planecane wrote:
Interested wrote:
Did they use manual trim on the Lion air flight that didn't crash??

That's a very good question. Since they cut off electric trim you have to assume they did. I can't imagine they flew 2 hours or whatever it was without trimming.


Well if they did and it's as rare an occurrence as people say it is then I'm staggered that the plane gets to fly the next day with passengers on it?

Surely certain failings on a plane warrant a grounding and because this was so rare it should qualify

Should certainly qualify in the future?

Not much between a disaster and a safe flight other than a jump seat pilot?

Yet look how the two occurrence get treated so differently just because the first plane landed safely in the end?


It is absolutely inexplicable that the prior Lion Air flight didn't prompt an investigation. They should have grounded that aircraft and had their maintenance team analyze the FDR to find out what happened. Boeing should have been consulted as well. If they had done this, perhaps the EAD and development of the software fix would have been prompted without a crash. ET might have crashed anyway if the same EAD/crew training had been released. But, you never know.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 6:20 pm

Interested wrote:
morrisond wrote:
xmp125a wrote:


I'm not going to disagree with you on the Pilot's part in either crash .


So if you agree with the above isn't that substantial enough to stop worrying about the pilots actions and to focus on what Boeing need to do to stop pilots anywhere in the world facing a similar situation in the future

I think we all accept that huge mistakes in design and implementation and communication have been made by Boeing. The CEO has just apologised for what's happened again and acknowledged they need to regain trust etc. He's said it's going to be a gradual process.

Ive seen the head of the US pilots union saying it's inexcusable to blame the pilots for these crashes and saying shame on Boeing for do so. He's not head of the Ethiopian pilots union.

Ive just seen the guy who wrote the technical guide for Boeing 737s saying the flight would have been saved had the disagree light worked whilst the CEO of Boeing on same day accepts that was a mistake etc

Isn't that enough to just move on now and stop clutching at any kind of real blame for the pilots and just accept Boeing messed up and now lets get this sorted for future pilots and passengers

I said it weeks ago - I never want to be on a plane that ever needs these manual trim procedures using. They scare the life out of me. I can't believe they even exist in this day and age. So let's just get back to having planes that are designed so these trims are never needed. And when they are you can't die whilst pilots struggle to have to use them.

For sure Morrison if you want these guys trained to use the trim etc let's do it as well. But that's not the real issue here. The Max flawed design has led us to spend weeks analysing and dissecting the ins and outs of something we should never even need to be discussing.


Nice - taking partial quotes again and ignoring my comments about training. I have always said it's a training issue.

You better never fly on an A320 then either as it has a backup trim wheel.

The technical writer said - it might have been saved - there was a lot of hedging in his response. If they had trimmed out the out of trim with Electric before switching it off or never put up the flaps or disengaged TOGA thrust they might have been saved as well.

All the conditions the ET Pilots were were right on the front page of the FCOM update. If they had read that and understood it - there should have been no issue identifying MCAS intervention.
 
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PixelFlight
Posts: 508
Joined: Thu Nov 08, 2018 11:09 pm

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 6:26 pm

GalaxyFlyer wrote:
How did you get on board any plane—they all have trimming systems. Boeing’s since the 707. Airbus uses software which is far more complex than cables and pulleys.

On Airbus this depend of the model, but the complexity is more about the redundancy than from the software.
A318/A319/A320/A321:
ELECTRICAL CONTROL:
- In normal operation, le ELAC2 controls the elevators and the horizontal stabilizer, and the green and yellow hydraulic jacks drive the left and right elevator surfaces respectively. The THS is driven by N°1 of three electric motors.
- If a failure occurs in ELAC2 or the associated hydraulic systems or hydraulic jacks, the system shifts pitch control to ELAC1. ELAC1 then controls the elevators via the blue hydraulic jacks and controls the THS via the N°2 electric motor.
- If neither ELAC1 nor ELAC2 is available, the system shifts pitch control either to SEC1 or to SEC2, depending on the status of associated circuits, and to THS motor N°2 or N°3.

MECHANICAL CONTROL:
Mechanical control of the THS is available from the pitch trim wheel at any time if either the green or the yellow hydraulic system is functioning. Mechanical control from the pitch trim wheel has priority over electrical control.

A350:
No trim wheel anymore. An double electrical manual trim switch command the E1 "Side 1 Electrical Emergency Power" and the E3 "Side 1 Electrical Normal Power" THSA (Trim Horizontal Stabilizer Actuator).

On all models, the software trim for long term actions the horizontal stabilizer to neutralize the elevator used for short-term actions. This is basically a very low pass filter, something relatively easy to do on a FBW system (and certainly more simple and safe than the repetitive discontinuous aggressively fast moving Boeing MCAS design).
 
morrisond
Posts: 1178
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 6:47 pm

mjoelnir wrote:
morrisond wrote:
PW100 wrote:

Apparently, forgot your own advise . . . :



Nice - taking quotes totally out of context and reusing them. That was in response to poster implying that Boeing never gave Customers any information or procedures to deal with MCAS after Lionair. Now it's debatable how effective those procedures were - but they did give them to Airlines - they did not totally bury there heads in the sand and say there are no issues.


Boeing did practical nothing. They did not explain how MCAS functioned. They did not give out how you recognize and train for MCAS failure mode. They did not fix the simulators so they would show how MCAS works and how it behaves with an AoA failure.
Boeing just pointed to the runaway trim procedure.
Boeing even kept quite over the non existence of the light declaring AoA disagree, pointing exactly at the situation that could produce a MCAS going amok situation. Even if this light should have been a standard feature and being described in the manual.

It is astonishing how you want to leave Boeing of the hook and accuse everybody else.


Please read Page 32-33 of the preliminary crash report - how does that not make the condition clear and show a way to deal with it. This is a different procedure than runaway trim.

Please read it before replying again https://leehamnews.com/wp-content/uploa ... ET-AVJ.pdf
 
XRAYretired
Posts: 488
Joined: Fri Mar 15, 2019 11:21 am

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 7:07 pm

morrisond wrote:
Interested wrote:
morrisond wrote:

I'm not going to disagree with you on the Pilot's part in either crash .


So if you agree with the above isn't that substantial enough to stop worrying about the pilots actions and to focus on what Boeing need to do to stop pilots anywhere in the world facing a similar situation in the future

I think we all accept that huge mistakes in design and implementation and communication have been made by Boeing. The CEO has just apologised for what's happened again and acknowledged they need to regain trust etc. He's said it's going to be a gradual process.

Ive seen the head of the US pilots union saying it's inexcusable to blame the pilots for these crashes and saying shame on Boeing for do so. He's not head of the Ethiopian pilots union.

Ive just seen the guy who wrote the technical guide for Boeing 737s saying the flight would have been saved had the disagree light worked whilst the CEO of Boeing on same day accepts that was a mistake etc

Isn't that enough to just move on now and stop clutching at any kind of real blame for the pilots and just accept Boeing messed up and now lets get this sorted for future pilots and passengers

I said it weeks ago - I never want to be on a plane that ever needs these manual trim procedures using. They scare the life out of me. I can't believe they even exist in this day and age. So let's just get back to having planes that are designed so these trims are never needed. And when they are you can't die whilst pilots struggle to have to use them.

For sure Morrison if you want these guys trained to use the trim etc let's do it as well. But that's not the real issue here. The Max flawed design has led us to spend weeks analysing and dissecting the ins and outs of something we should never even need to be discussing.


Nice - taking partial quotes again and ignoring my comments about training. I have always said it's a training issue.

You better never fly on an A320 then either as it has a backup trim wheel.

The technical writer said - it might have been saved - there was a lot of hedging in his response. If they had trimmed out the out of trim with Electric before switching it off or never put up the flaps or disengaged TOGA thrust they might have been saved as well.

All the conditions the ET Pilots were were right on the front page of the FCOM update. If they had read that and understood it - there should have been no issue identifying MCAS intervention.



If you are going to quote, why do it partially?. This is it:

'Chris Brady, a pilot and author of The Boeing 737 Technical Guide said: "I'm fairly confident that the Ethiopian Airlines flight probably would not have crashed if they had had the AOA disagree alert" on the aircraft.
Mr Brady believes that if there had been an alert warning light showing that the AOA sensors were giving different readings, then the pilots might have followed an emergency procedure at an earlier point in the doomed flight. '

https://www.bbc.co.uk/news/amp/business-48461110

Earlier, as in before MCAS was operative in my opinion.

Ray
 
afgeneral
Posts: 86
Joined: Sat Jul 02, 2016 2:43 pm

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 7:14 pm

planecane wrote:
PixelFlight wrote:
PW100 wrote:
An important difference between MAX and earlier 737 versions is, that on earlier versions automatic trimming (be it STS, Mach Trim, autopilot, whatever), automatic trimming is stopped when an opposite movement is made on the control column. Which makes sense: if the auto systems are commanding nose down, and the crew want to go nose-up by pulling on the yoke, it makes sense to stop the opposite trimming.

From that post about the STS and control column in the opposite direction:
https://www.pprune.org/tech-log/614997-b-737-speed-trim-system.html#post10300036
No, it will happily continue to trim even if you push (you need to) forward on the controls after take off when you accelerate. It will stop when you apply opposite trim. Which I do on every take off since STS trims the aircraft out of trim. It normally takes 2-3 turns of trim, depending on when you start to trim.
Weird system!

The difference between the STS and the MCAS is how there respective code can go wrong. There are some grey area about the STS as it can potentially send dangerous stab trim command too if it goes very erratic. Satcom Guru explained that STS (and MCAS) run on a single CPU on an single side FCC in manual flight mode. Could be an another certification issue for the 737 NG and 737 MAX now that the design is reviewed in detail...


I think that STS has proven itself not to be a problem. With 7000 NGs flying around for what has to be over 50 million flights, the fact that there hasn't been an STS related crash would seem to prove that it is not a safety issue.


Do we really know that? Are there some previously unexplained crashes which may now be explained by STS? Did they review any past incidents to make sure?
 
sillystrings
Posts: 28
Joined: Thu May 30, 2019 7:06 pm

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 7:25 pm

morrisond wrote:
Please read Page 32-33 of the preliminary crash report - how does that not make the condition clear and show a way to deal with it. This is a different procedure than runaway trim.


Interestingly enough the FCOM bulletin subject is "Uncommanded Nose Down Stabilizer Trim due to Erroneous Angle of Attack (AOA) During Manual Flight only".

Throughout the bulletin Boeing is emphasizing that this problem caused by erroneous AOA data. Is it possible that since the crew didn't see the AOA DISAGREE message they didn't make the connection? Wouldn't it be reasonable for them to expect to see the AOA DISAGREE message before coming to the conclusion they are facing that problem?
 
morrisond
Posts: 1178
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 7:35 pm

XRAYretired wrote:
morrisond wrote:
Interested wrote:

So if you agree with the above isn't that substantial enough to stop worrying about the pilots actions and to focus on what Boeing need to do to stop pilots anywhere in the world facing a similar situation in the future

I think we all accept that huge mistakes in design and implementation and communication have been made by Boeing. The CEO has just apologised for what's happened again and acknowledged they need to regain trust etc. He's said it's going to be a gradual process.

Ive seen the head of the US pilots union saying it's inexcusable to blame the pilots for these crashes and saying shame on Boeing for do so. He's not head of the Ethiopian pilots union.

Ive just seen the guy who wrote the technical guide for Boeing 737s saying the flight would have been saved had the disagree light worked whilst the CEO of Boeing on same day accepts that was a mistake etc

Isn't that enough to just move on now and stop clutching at any kind of real blame for the pilots and just accept Boeing messed up and now lets get this sorted for future pilots and passengers

I said it weeks ago - I never want to be on a plane that ever needs these manual trim procedures using. They scare the life out of me. I can't believe they even exist in this day and age. So let's just get back to having planes that are designed so these trims are never needed. And when they are you can't die whilst pilots struggle to have to use them.

For sure Morrison if you want these guys trained to use the trim etc let's do it as well. But that's not the real issue here. The Max flawed design has led us to spend weeks analysing and dissecting the ins and outs of something we should never even need to be discussing.


Nice - taking partial quotes again and ignoring my comments about training. I have always said it's a training issue.

You better never fly on an A320 then either as it has a backup trim wheel.

The technical writer said - it might have been saved - there was a lot of hedging in his response. If they had trimmed out the out of trim with Electric before switching it off or never put up the flaps or disengaged TOGA thrust they might have been saved as well.

All the conditions the ET Pilots were were right on the front page of the FCOM update. If they had read that and understood it - there should have been no issue identifying MCAS intervention.



If you are going to quote, why do it partially?. This is it:

'Chris Brady, a pilot and author of The Boeing 737 Technical Guide said: "I'm fairly confident that the Ethiopian Airlines flight probably would not have crashed if they had had the AOA disagree alert" on the aircraft.
Mr Brady believes that if there had been an alert warning light showing that the AOA sensors were giving different readings, then the pilots might have followed an emergency procedure at an earlier point in the doomed flight. '

https://www.bbc.co.uk/news/amp/business-48461110

Earlier, as in before MCAS was operative in my opinion.

Ray


They didn't follow any other procedure 100% - why does he assume they would have done so in this case? He also says "Fairly Confident" and "Might" - that's different than " the guy who wrote the technical guide for Boeing 737s saying the flight would have been saved had the disagree light worked"
 
User avatar
PixelFlight
Posts: 508
Joined: Thu Nov 08, 2018 11:09 pm

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Thu May 30, 2019 7:50 pm

morrisond wrote:
They didn't follow any other procedure 100% - why does he assume they would have done so in this case?

"morrisond", for me, you just passed the red line of unacceptable wording about the pilots that was killed. :talktothehand:

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