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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 3:34 pm
by morrisond
PixelFlight wrote:
morrisond wrote:
As they were flying at full thrust at over Vmo - well above normal operating speed and the speed limit below 10,000' - it's as bad as no thrust and below stall speed - the trim wheel isn't going to help much there either.

You still don't get the fact that Vmo is just an arbitrary safety margin below the much higher design speed. The trim wheels must be usable up to the design speed, not just up to Vmo. And the difficulty to move the wheels was also probably linked to the extreme miss-trim induced by the MCAS. There are still the question why the pilots can't easily fully neutralize the stab trim (i have proposed two responses).


So what is the "Design speed" and please list the Regulation where the trim wheels have to be usable above Vmo.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 3:35 pm
by morrisond
asdf wrote:
morrisond wrote:
They had two working airspeed indicators. A proper crosscheck would have told them the stall warning was false.


näh

they had two different airspeeds indicated
they did NOT knew which one was correct

i do not know if that NNC of the QRH is correct because someone here in the thread mentioned his QRH looks different (but he didnt tell what it looks like)

NNC of the QRH you reference

7 Refer to the Flight With Unreliable Airspeed table in the Performance Inflight chapter and set the pitch attitude and thrust setting for the current airplane configuration and phase of flight.
8 When in trim and stabilized, cross check the captain, first officer and standby airspeed indicators. An airspeed indication that differs by more than 20 knots or 0.03 Mach from the airspeed shown in the table should be considered unreliable.
9 Choose one:
Reliable airspeed indication can be determined:
Use the most reliable airspeed source for the remainder of the flight.
Go to step 10
Reliable airspeed indication can not be determined:
Go to step 12
10 Flight director switch (reliable side) . . . . . . . .ON
11 Autopilot (reliable side) . . . . . . . . . . . . . .Engage
12 Set pitch attitude and thrust from the Flight With Unreliable Airspeed table in the Performance Inflight chapter for the airplane configuration and phase of flight, as needed.

(Performance section)
General General - Flight With Unreliable Airspeed Flight With Unreliable Airspeed/ Turbulent Air Penetration Altitude and/or vertical speed indications may also be unreliable.
Climb (280/.76) Flaps Up, Set Max Climb Thrust


thats what the ET guys did


No they would have had three Airspeeds indicated.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 3:39 pm
by Raiden
oschkosch wrote:
A very indepth report by Seattle Times!

https://www.seattletimes.com/business/b ... -messages/

The bottom line is that the erratic behavior described in the 2016 chat by 737 MAX chief technical pilot Mark Forkner revealed a software bug in the MAX flight simulator he was using, a pilot training machine that he and his colleagues were then fine-tuning to get it ready for the MAX’s entry into service. It was not evidence of the flaws that later showed up on the real airplane’s new flight-control system — known as the Maneuvering Characteristics Augmentation System (MCAS) — that caused the fatal crashes of the jets in Indonesia and Ethiopia.


Boeing last Friday offered no real evidence in its defense. On Sunday, it offered weak evidence: just a general statement by Forkner’s lawyer. Forkner is refusing to talk or to provide information under his Fifth Amendment right against self-incrimination. In addition, the second part of Boeing’s defense on Sunday — its claim that the FAA knew all about the changes it made to MCAS — is questionable.

Multiple reports, initially in the Seattle Times, and most recently in the report by a team of international regulators, show that though some within the FAA may have been aware of some changes to MCAS, the FAA safety engineers tasked with analyzing its safety did not.


It doesn’t change the conclusion that MCAS as originally designed did lead to the accidents and the deaths of 346 people.
Why on earth is the guy (Forkner) invoking 5th amendment and refusing to turn over documents?

This is in my view an ugly turn for 737 MAX. The guy played a key role in the development of the aircraft. He has no business not co-operating. This is bordering on a cover-up now. People are behaving like crime suspects rather than accident material witnesses.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 3:42 pm
by frmrCapCadet
not beyond the realm but statistically improbable.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 3:42 pm
by jetmatt777
seahawk wrote:
Nice to see Boeing on track, hopefully the FAA is fast and the MAX returns to the skies in November.


Why would you hope they are fast just for the sake of being fast?

If you are getting a health screening do you want your doctor to be fast or do you want your doctor to be meticulous and thorough?

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 3:44 pm
by jetmatt777
Raiden wrote:
oschkosch wrote:
A very indepth report by Seattle Times!

https://www.seattletimes.com/business/b ... -messages/

The bottom line is that the erratic behavior described in the 2016 chat by 737 MAX chief technical pilot Mark Forkner revealed a software bug in the MAX flight simulator he was using, a pilot training machine that he and his colleagues were then fine-tuning to get it ready for the MAX’s entry into service. It was not evidence of the flaws that later showed up on the real airplane’s new flight-control system — known as the Maneuvering Characteristics Augmentation System (MCAS) — that caused the fatal crashes of the jets in Indonesia and Ethiopia.


Boeing last Friday offered no real evidence in its defense. On Sunday, it offered weak evidence: just a general statement by Forkner’s lawyer. Forkner is refusing to talk or to provide information under his Fifth Amendment right against self-incrimination. In addition, the second part of Boeing’s defense on Sunday — its claim that the FAA knew all about the changes it made to MCAS — is questionable.

Multiple reports, initially in the Seattle Times, and most recently in the report by a team of international regulators, show that though some within the FAA may have been aware of some changes to MCAS, the FAA safety engineers tasked with analyzing its safety did not.


It doesn’t change the conclusion that MCAS as originally designed did lead to the accidents and the deaths of 346 people.
Why on earth is the guy (Forkner) invoking 5th amendment and refusing to turn over documents?

This is in my view an ugly turn for 737 MAX. The guy played a key role in the development of the aircraft. He has no business not co-operating. This is bordering on a cover-up now. People are behaving like crime suspects rather than accident material witnesses.


It's because they are crime suspects. The Dept of Justice is pursuing a criminal investigation. That is completely independent of the FAA's certification of the airplane.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 4:36 pm
by mrbots
Is it possible that the EASA has the second update (bitflip issue) as a RTS requirement and the FAA will allow it to be rolled out afterwards?

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 4:44 pm
by seahawk
jetmatt777 wrote:
seahawk wrote:
Nice to see Boeing on track, hopefully the FAA is fast and the MAX returns to the skies in November.


Why would you hope they are fast just for the sake of being fast?

If you are getting a health screening do you want your doctor to be fast or do you want your doctor to be meticulous and thorough?


Because shareholders and airlines have an interest to let the plane fly asap.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 4:45 pm
by 9w748capt
seahawk wrote:
jetmatt777 wrote:
seahawk wrote:
Nice to see Boeing on track, hopefully the FAA is fast and the MAX returns to the skies in November.


Why would you hope they are fast just for the sake of being fast?

If you are getting a health screening do you want your doctor to be fast or do you want your doctor to be meticulous and thorough?


Because shareholders and airlines have an interest to let the plane fly asap.


What if the plane is unstable and unsafe to fly? Do they still have an obligation to let it?

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 4:47 pm
by Revelation
Why on earth is the guy (Forkner) invoking 5th amendment and refusing to turn over documents?

This is in my view an ugly turn for 737 MAX. The guy played a key role in the development of the aircraft. He has no business not co-operating. This is bordering on a cover-up now. People are behaving like crime suspects rather than accident material witnesses.

It's because they are crime suspects. The Dept of Justice is pursuing a criminal investigation. That is completely independent of the FAA's certification of the airplane.

Indeed.

The recent ST article walking back the notion that Forkner was seeing MCAS firing quoted two people who would not go on the record since they did not want a visit by the FBI and/or a trip to the grand jury.

I've had occasion to be interviewed by the FBI and will say they are damned good at their jobs.

If you have anything to hide (which I did not) I would suggest doing what Forkner did and engaging a lawyer.

His job involved liaison between Boeing and FAA so he is positioned to be the perfect fall guy.

Bringing the lawyer into the loop and taking the 5th will give him more control over what he says and who he says it to.

That may turn out to be a valuable thing.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 4:50 pm
by jetmatt777
seahawk wrote:
jetmatt777 wrote:
seahawk wrote:
Nice to see Boeing on track, hopefully the FAA is fast and the MAX returns to the skies in November.


Why would you hope they are fast just for the sake of being fast?

If you are getting a health screening do you want your doctor to be fast or do you want your doctor to be meticulous and thorough?


Because shareholders and airlines have an interest to let the plane fly asap.


And the traveling public, and even non traveling public on the ground, have an overwhelming interest in the MAX not creating more craters on the planet.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 4:51 pm
by jetmatt777
seahawk wrote:
jetmatt777 wrote:
seahawk wrote:
Nice to see Boeing on track, hopefully the FAA is fast and the MAX returns to the skies in November.


Why would you hope they are fast just for the sake of being fast?

If you are getting a health screening do you want your doctor to be fast or do you want your doctor to be meticulous and thorough?


Because shareholders and airlines have an interest to let the plane fly asap.


And the traveling public, and even non traveling public on the ground, have an overwhelming interest in the MAX not creating more craters on the planet.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 4:53 pm
by keesje
Revelation wrote:
Why on earth is the guy (Forkner) invoking 5th amendment and refusing to turn over documents?

This is in my view an ugly turn for 737 MAX. The guy played a key role in the development of the aircraft. He has no business not co-operating. This is bordering on a cover-up now. People are behaving like crime suspects rather than accident material witnesses.

It's because they are crime suspects. The Dept of Justice is pursuing a criminal investigation. That is completely independent of the FAA's certification of the airplane.

Indeed.

The recent ST article walking back the notion that Forkner was seeing MCAS firing quoted two people who would not go on the record since they did not want a visit by the FBI and/or a trip to the grand jury.

I've had occasion to be interviewed by the FBI and will say they are damned good at their jobs.

If you have anything to hide (which I did not) I would suggest doing what Forkner did and engaging a lawyer.

His job involved liaison between Boeing and FAA so he is positioned to be the perfect fall guy.

Bringing the lawyer into the loop and taking the 5th will give him more control over what he says and who he says it to.

That may turn out to be a valuable thing.



Agree, big cooperations love to concentrate problems at individuals & remove them (well paid if required).
It's quicker and easier than reviewing soft topics like "culture" and "strategy" and line of command.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 5:23 pm
by lowbank
seahawk wrote:
jetmatt777 wrote:
seahawk wrote:
Nice to see Boeing on track, hopefully the FAA is fast and the MAX returns to the skies in November.


Why would you hope they are fast just for the sake of being fast?

If you are getting a health screening do you want your doctor to be fast or do you want your doctor to be meticulous and thorough?


Because shareholders and airlines have an interest to let the plane fly asap.


That’s the ticket, let’s get it back up without proper scrutiny, who cares if it kills another 300 none entity foreigners.

At least the share holders are happy.

One comment deleted on reflection.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 5:27 pm
by AABusDrvr
FluidFlow wrote:
planecane wrote:
FluidFlow wrote:


In the electric trim regime I see 5 possible failures that lead to run away trim:

1. The manual electric trim inputs have a short or are stuck or any other failure
2. The actuator fails and just trims till the max/min
3. The wiring fails/shortcuts
4. The computer fails
5. The manual non-electric trim fails

Now how does this impact the pilot, or how is it felt:

1. The trim is continuous and can not be stopped if smacking the control column does not release the switches. Nothing can be done except hit the cut out switches
2. Will be a continuous trim that will not stop if you flick the thumb switches
3. same as 2.
4. This is actually the tricky part because the manual electric trim does still work and if activated will kill the signal from the computer because it has priority over the computer
5. This would be a death sentence because no matter what both ways of trimming would be tarnished and there would be no real way to use electric trim if manual is prioritized over electrical

Now for Point 4:

If the computer fails, or in case of MCAS actually does what it supposed to do (trim with unlimited authority no matter what as long as AoA>X) then it does not present itself as a runaway because:

1. Electric trim does still work and
2. After you did trim with electric trim there is no immediate restart of trim caused by the computer, there is a 5 second break. This actually means that the trim action is deliberate by the computer and not a malfunction.

The problem is that it was never stated that a false input from the AoA probe will lead to step-wise nose down trim.
The problem could also be a broken feel computer. At the end it is, with no knowledge of the engineering and function of the software, almost impossible to conclude that a broken AoA sensor leads to the computer deliberately apply step-wise nose down input.
The real problem seems to be that a broken AoA probe leads to a cascade of problems in the 737 without ever telling the pilot that the probe is broken. The trim did not run away or had a failure, all the trim inputs from the computer were legit and working as intended. From the aircraft perspective only a full nose down input was the solution to a problem that actually was not there.


The reason that NNCs exist is so that the pilots do not need to be diagnosing the cause of issues. They shouldn't be going through the troubleshooting steps that you have listed. Upon recognizing a runaway stabilizer (regardless of cause) they are supposed to follow the runaway stabilizer NNC. If that doesn't work, then they can move on to try on the fly troubleshooting.

As I have previously stated, IF the limits placed on the electric trim on the MAX prevented the pilots from getting back into trim using the thumb switches then there was nothing they could do to recover short of the roller coaster procedure if the forces were too great to turn the manual wheel.


The problem is, it is not a run away stabilizer trim, because there is no malfunction in the trim system or the computer. The trim inputs from the computer were deliberate, had a fixed duration, a fixed deflection, a given activation interval and a single purpose: to reduce AoA. It was also possible to stop the trim inputs by the computer, by overriding them with manual electric trim and I guess also by manually turning the trim wheels. Nothing here points to a run away stabilizer. Nothing in the whole system happened unintended except it was the classical crap input = crap output. This should have been addressed by Boeing as catastrophic because the system was and maybe still is not able to vet the input parameters. So crap input will still lead to crap output.


While not a runaway stabilizer, in the traditional sense, it's still the stab trim doing something you don't want it to do. The runaway stabilizer QRH procedure solves any electric stabilizer trim problems, and is the proper procedure to apply. Remove the power to the electric systems, use the manual trim, and drive on. Actually, it works in just about every airplane with electric pitch trim. It's the way I, and pretty much everyone I know was trained from the beginning.

planecane wrote:
Or an engine failure on takeoff. They'd better be responding very quickly.


A simple engine failure on takeoff, in a jet powered airplane is actually a pretty benign event. They only thing you are required to do, is keep the nose pointed the right direction with the rudder, fly the proper airspeed, and retract the gear. A V1 cut shouldn't even get anyone excited. Granted, if you don't get the rudder squared away in a reasonable amount of time, things can get interesting, but thats just "flying the airplane" nothing else happens in an a hurry.


Amiga500 wrote:
morrisond wrote:
As they were flying at full thrust at over Vmo - well above normal operating speed and the speed limit below 10,000' - it's as bad as no thrust and below stall speed - the trim wheel isn't going to help much there either.


You keep on ignoring the stall warning they were receiving.

It is likely they had doubts over their airspeed indicators, so probably were attempting thrust and AoA flight... and failing miserably due to the unwanted intervention of MCAS.


MCAS didn't activate until they retracted the flaps. By that point, they should have had the stall warning squared away, and known it was a false warning. If they hadn't figured that out yet, they never should have retracted the flaps, or tried to engage the autopilot.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 5:27 pm
by 426Shadow
This topic is so polarizing I cannot believe there hasn't been multiple warnings or a lock.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 5:31 pm
by MSPNWA
jetmatt777 wrote:
seahawk wrote:
Nice to see Boeing on track, hopefully the FAA is fast and the MAX returns to the skies in November.


Why would you hope they are fast just for the sake of being fast?

If you are getting a health screening do you want your doctor to be fast or do you want your doctor to be meticulous and thorough?


Hoping the FAA is fast =/= fast for the sake of being fast or not being meticulous and thorough.

When you have tests done for a diagnosis, do you want a unnecessarily slow process that delays the start of treatment? Fast in this case means doing the right job quickly. We all should be hoping for that as people around the world will benefit from a speedy, safe return.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 5:31 pm
by lowbank
I will be clear, I want the MAX back in the air as soon as those given the job of judging it’s safe agree it is.

Not before.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 5:47 pm
by BaconButty
planecane wrote:
Can we at least give this argument a rest? Normal automatic trim does not operate continuously for over 9 seconds.

If the trim wheel is spinning continuously for several seconds and simultaneously the force to maintain level flight is significantly increasing that would indicate a runaway stabilizer.

I am willing to bet that when the final Lion Air report is released, if it has a full CVR transcript, there will be no point where the crew determines there isn't a runaway stabilizer because it is intermittent.


Sorry for the lateness in reply. I think others have challenged you on that anyway, but even if you were right, and a crew could (mis)identify runaway stab and run through the checklist before it mysteriously cuts out, the notion that "both accidents presented as a runaway stabilizer" is patently false. You have to take in to account all the diagnostic information made available (something the JATR report is full of). And in the case of the ET crash, the Stick shaker was (iirc) the first indication they have, followed by various warnings and the autopilot cutting out etc and only at flap retraction does MCAS kick in. The happy path "3 seconds to respond" becomes very silly*. Which is why, in any sensible implementation of MCAS, it would have had redundant sensors and self-disabling when they disagreed - like what is happening.

As I said, the phrase I find offensive is "both accidents presented as a runaway stabilizer" - I've seen the last four words far to often in the last year to be coincidence.PR is up to their old naughty tricks again?

* From the JATR report
Finding F6.7-A: The Boeing analysis of erroneous MCAS activation did not adequately take into account what else might be happening at the same time, such as the possibility of an AOA failure with all its associated flight deck effects potentially distracting the crew from recognizing the trim action.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 5:48 pm
by asdf
lowbank wrote:
seahawk wrote:
Because shareholders and airlines have an interest to let the plane fly asap.


That’s the ticket, let’s get it back up without proper scrutiny, who cares if it kills another 300 none entity foreigners.
At least the share holders are happy.


isnt there someone in the glass palace in chicago who knows how statistics work?
in the last year we heared a lot about certifications, regulations, augmentations, workload, grandfathering, bad maintanance, bad pilots, bad FAA ...

but that is not the point at all

the MAX is - under heavy commercial pressure - equipped with engines that do not fit to the wings
The result was a plane with an unusual pitch- and critical flight behavior within the usual flight maneuvering areas
managers and technician probably thought they could find a way to make it aerodynamical neutral and safe but they failed

such a flight behavior can only be well compensated in a completely electronically controlled aircraft, but not in the MAX

which means that the 737MAX inevitably has a much higher incident and accident risk than, for example, a 737NG.

what did the boeing management think in 2016?
"....It'll take a couple of years to catch everyone's attention, we just take our bonuses in 2019 and go ... "?

If a 737MAX makes as many starts and landings (and evasive maneuvers and bad weather- and shear wind landings ect ect) as a 737NG, then a 737MAX will be measurably more involved in incidents or accidents. No matter what MCAS 2.0 or 3.0 will look like.

That's just statistics.

if that becomes visible to the public within a few months, maybe in a year or two, what is boeing doing then?
und what are the airlines doing with a lot of planes no one will step onto ..?

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 5:53 pm
by seahawk
9w748capt wrote:
seahawk wrote:
jetmatt777 wrote:

Why would you hope they are fast just for the sake of being fast?

If you are getting a health screening do you want your doctor to be fast or do you want your doctor to be meticulous and thorough?


Because shareholders and airlines have an interest to let the plane fly asap.


What if the plane is unstable and unsafe to fly? Do they still have an obligation to let it?


In that case they should be fast in pointing out the problems. Being fast does not mean to not be thorough. If they have any doubts they need to be fast to voice them. If they think they will need longer to check the software, they need to be fast to voice that too. Nothing is gained when we have 10 instead of 6 weeks of silence in the process and the MAX flies after that.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 5:57 pm
by planecane
BaconButty wrote:
planecane wrote:
Can we at least give this argument a rest? Normal automatic trim does not operate continuously for over 9 seconds.

If the trim wheel is spinning continuously for several seconds and simultaneously the force to maintain level flight is significantly increasing that would indicate a runaway stabilizer.

I am willing to bet that when the final Lion Air report is released, if it has a full CVR transcript, there will be no point where the crew determines there isn't a runaway stabilizer because it is intermittent.


Sorry for the lateness in reply. I think others have challenged you on that anyway, but even if you were right, and a crew could (mis)identify runaway stab and run through the checklist before it mysteriously cuts out, the notion that "both accidents presented as a runaway stabilizer" is patently false. You have to take in to account all the diagnostic information made available (something the JATR report is full of). And in the case of the ET crash, the Stick shaker was (iirc) the first indication they have, followed by various warnings and the autopilot cutting out etc and only at flap retraction does MCAS kick in. The happy path "3 seconds to respond" becomes very silly*. Which is why, in any sensible implementation of MCAS, it would have had redundant sensors and self-disabling when they disagreed - like what is happening.

As I said, the phrase I find offensive is "both accidents presented as a runaway stabilizer" - I've seen the last four words far to often in the last year to be coincidence.PR is up to their old naughty tricks again?

* From the JATR report
Finding F6.7-A: The Boeing analysis of erroneous MCAS activation did not adequately take into account what else might be happening at the same time, such as the possibility of an AOA failure with all its associated flight deck effects potentially distracting the crew from recognizing the trim action.


Read the reply from AAbusdriver above. He is a 737 pilot and I believe he flew the MAX. Then put the argument to rest.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 5:57 pm
by morrisond
asdf wrote:

the MAX is - under heavy commercial pressure - equipped with engines that do not fit to the wings
The result was a plane with an unusual pitch- and critical flight behavior within the usual flight maneuvering areas
such flight behavior can only be well compensated in a completely electronically controlled aircraft, but not in the MAX

which means that the 737MAX inevitably has a much higher incident and accident risk than, for example, a 737NG.

what did the boeing management think in 2016?
"....It'll take a couple of years to catch everyone's attention, we just take our bonuses in 2019 and go ... "?

If a 737MAX makes as many starts and landings (and evasive maneuvers and bad weather- and shear wind landings ect ect) as a 737NG, then a 737MAX will be measurably more involved in incidents or accidents. No matter what MCAS 2.0 or 3.0 will look like.

That's just statistics.

if that becomes visible to the public within a few months, maybe in a year or two, what is boeing doing then?
und what are the airlines doing with a lot of planes no one will step onto ..?



When you are talking about the future that is a prediction. It's nothing to do with stats as MAX with MCAS V2.0 will be different than MCAS 1.0 and it hasn't flown yet.

Please explain what mysterious handling issues the MAX might have other than the controls getting a little light near stall when light and near the aft COG limit and assuming MCAS 2.0 doesn't bring it back into line, and then the pilots miss the stick shaker the elevator feel computer doubling the control force, the warning alarms and the frame buffeting.

Getting that close to stall should happen literally (making a prediction) maybe 1 in 100,000 flights and then if the pilots miss all the other stall prevention systems then yes it will crash.

But at the point is it the plane's fault or the pilot's fault?

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 6:01 pm
by lhrnue

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 6:13 pm
by asdf
morrisond wrote:
When you are talking about the future that is a prediction. It's nothing to do with stats as MAX with MCAS V2.0 will be different than MCAS 1.0 and it hasn't flown yet.

Safe flying - like most processes - is the elimination of errors and problems
If plane A has a non critical, usual up-pitch behavior but plane B has a problematic one, then plane B is less secure than plane A. This is largely independent of what is being done in aircraft B on technical measures to disguise this behavior

morrisond wrote:
Please explain what mysterious handling issues the MAX might have other than the controls getting a little light near stall when light and near the aft COG limit and assuming MCAS 2.0 doesn't bring it back into line, and then the pilots miss the stick shaker the elevator feel computer doubling the control force, the warning alarms and the frame buffeting.

Do we really have to go through this passage again and again?
All the known facts (and no, I do not count them again now again, because i think you know them probably better as me) point out that the 737MAX has mounted not only the engines in a fundamentally unsuitable position, but that the resulting problematic flight behavior of the 737MAX in the tests in reality then was even more problematic than originally suspected.
It is certainly not only a "nonlinear stick behavior" but rather a tilting of the stickload into the negative, already quite outside of the linear flight
That is not mysterious, that's just irresponsible

morrisond wrote:
Getting that close to stall should happen literally (making a prediction) maybe 1 in 100,000 flights and then if the pilots miss all the other stall prevention systems then yes it will crash.

you got it!
its statistic!
and usually ist measured in flighthours
how fast do you get 200.000 flight hours (your mentioned 100.000 flights) worldwide with 2000 MAXs flying all day long?
and how many stalls does it need in a unusual reacting, difficult for the not in a SIM training prepaered crews to recover 737MAX till its the next disaster?

i would make a uneducated guess on 14 to 18 months
but i could be wrong
dont have my calculator at hand ...

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 6:38 pm
by asdf
seahawk wrote:
9w748capt wrote:
seahawk wrote:
Because shareholders and airlines have an interest to let the plane fly asap.

What if the plane is unstable and unsafe to fly? Do they still have an obligation to let it?

In that case they should be fast in pointing out the problems. ...


and what if they knew the problem since 2016 and had no plan B and thought they would get away with it and would not get caught...

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 6:48 pm
by MrBretz
Tomorrow will be an interesting day. Boeing will report quarterly earnings. I wonder if it will be before the market opens or after it closes. I guess it could be any time.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 6:49 pm
by morrisond
asdf wrote:
It is certainly not only a "nonlinear stick behavior" but rather a tilting of the stickload into the negative, already quite outside of the linear flight
That is not mysterious, that's just irresponsible

morrisond wrote:
Getting that close to stall should happen literally (making a prediction) maybe 1 in 100,000 flights and then if the pilots miss all the other stall prevention systems then yes it will crash.

you got it!
its statistic!
and usually ist measured in flighthours
how fast do you get 200.000 flight hours (your mentioned 100.000 flights) worldwide with 2000 MAXs flying all day long?
and how many stalls does it need in a unusual reacting, difficult for the not in a SIM training prepaered crews to recover 737MAX till its the next disaster?

i would make a uneducated guess on 14 to 18 months
but i could be wrong
dont have my calculator at hand ...


Why do you think the stick force goes into the negative? I don't think there are any reports anywhere that that happens.

So you are assuming the pilots are so bad or so poorly trained that all the other stall prevention systems don't stop them from crashing the plane? Even if they ignore all the warnings and do stall it (99 out of 100 shouldn't get to this point) - there basic training should take over and 99% of them should be able to recover.

You must think that the worldwide training system is radically even poorer than I do.

So if a stall situation happens 1 in 100,000 flights (and I'm totally guessing here but I suspect it's a lot higher) and the pilots save it 99.99% - that's 1 in 1 Billion Flights. Assuming 10,000 MAX's flying and 50,000 Flights each that's about a 50% of an MAX stall resulting in an fatality in the life of the program.

About the same as the NG - see ET409.

BTW recurrent stall training is now a requirement in the sims in the US.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 7:00 pm
by oschkosch
MrBretz wrote:
Tomorrow will be an interesting day. Boeing will report quarterly earnings. I wonder if it will be before the market opens or after it closes. I guess it could be any time.
3 or more Billion additional provisions causing another lose?

Gesendet von meinem SM-G950F mit Tapatalk

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 7:07 pm
by kalvado
Amiga500 wrote:
morrisond wrote:
They had two working airspeed indicators. A proper crosscheck would have told them the stall warning was false.


Do we know that for sure?

If a bird wiped out the AoA vane, then its not beyond the realms another bird wiped out the pitot tube on that side.

You need a pitot and AoA for speed calculation. That is why AoA out causes so many side effects - airspeed is now off.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 7:14 pm
by rheinwaldner
EA CO AS wrote:
My workgroup had the opportunity to have a presentation on the MAX by three B737 fleet captains, and they did a very deep dive into the FDR data for both the JT and ET accidents.

These kind of overconfident pilots would have created the next MAX crash.

In an other forum I observed a (first world) MAX pilot contributing a lot about the ET crash. You know what? After being in complete denial the longest time (she said things like: "Boeing did not officially admit, that MCAS exists" or "I am sure, that MCAS played no role, it must have been another technical issue"), she must have come to her senses recently and noticed how embarassing her posts were, as she went and deleted every single post in that thread. Having observed that, I think it is good that the MAX is grounded until these guys get a better understanding of their aircraft.

EA CO AS wrote:
They also had no qualms in pointing out that any B737 type-rated pilot shouldn't have lost either airplane, as both accidents presented as a runaway stabilizer, and the standard checklist for the B737 would have involved engaging the trim cutout switches.

So they simply did not understand how this incidents were presented to the crews.

B.t.w. well know and very experienced US pilots publicly have confirmed this, namely Sully and also Juan Browne.

morrisond wrote:
Pilots seem to have a hard time manually flying the NG when the Automation breaks as well - see ET409.

Thats not correct. Aviation safety globally is phenomenal. The NG being no outlier. Looking at single cases does not change that. In the five years before the MAX appeared one out 4.2 million flights crashed globally (for all possible reasons). The MAX crashed with equally proficient crews about once every 0.125 million flights. From this, it looks that fixing the MAX is the only thing needed to make global aviation safe again.

I gave you the failure rates earlier:
- Crashes per flights 2012-2017 globally: 0.00000024 -> one crash every 4.2 million flights
- As failure rates are additive I can take this as the sum and make an educated guess, how much was primarily a pilot failure and how much was primarily a system failure. Lets say 7/8 were pilot failures and 1/8 were because of system failures. So we get this:
- Crashes per flight primarily due to pilot failures: 0.00000021 (= 0.00000024 * 7/8) -> one crash every 4.7 million flights
- Crashes per flight primarily due to system failures: 0.00000003 (= 0.00000024 * 1/8 = 0.00000024 - 0.00000021) -> one crash every 33 million flights

Therefore, as typically proficient crews would be expected to crash a MAX once every 4.7 million flights, the observed crash rate of 0.000008 (about once every 0.125 million flights) clearly shows the one and only issue: the MAX!

The horrible crash rate of 0.000008 is entirely contributed by the flawed MAX systems. Which makes the MAX contributing a crash causing system failure rate 260 times higher than the 0.00000003 we got for all the other planes.

Therefore, the "just as much"-term in the following statement is hogwash:
morrisond wrote:
and it's not the pilots - it's the training system/airlines penny pinching just as much as Boeing is at fault for penny pinching/in pursuit of profit.


Truth is, fixing the MAX has so much more leverage than doing anything else, that it really should be the only topic. Improving the global crash rate of 0.00000024 is something entirely different and has nothing to do with the MAX grounding.

planecane wrote:
Can we at least give this argument a rest? Normal automatic trim does not operate continuously for over 9 seconds.

Neither does MCAS if you give a trim input. No, the MCAS incident did not present itself as a trim runaway. Saying otherwise should be put at rest.

planecane wrote:
They were supposed to run the runaway stabilizer NNC as written which would have them get back in trim before cutting out the switches.

If you would know the NNC, then you would know, that the NNC looks as follows:

....
* Control airplane pitch attitude manually with control column and main electric trim as needed.
* If runaway stops:
-> checklist completed.
* If not: STAB TRIM CUTOUT switches -> CUTOUT
...

See https://issuu.com/sytanic/docs/737_qrh_rev_digisuit, page 135

This means, that the MCAS malfunction can not be handled with this NNC because every time the pilot uses electric trim, the runaway stops and the CUTOUT checklist item is never reached.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 7:18 pm
by asdf
morrisond wrote:
Why do you think the stick force goes into the negative? I don't think there are any reports anywhere that that happens.

there are no reports on the 737MAX flight behavior without augmentation at all
so yes, well, there are no reports about a negativ stick force within the envelope neither

i suspect it because i can not imagine at all, that the responsible test pilotes @ boeing would ever have deside to raise the MCAS trim imput after the test flights above the intended level if they would have seen any other chance to get kinda control over that stick load.

morrisond wrote:
So you are assuming the pilots are so bad or so poorly trained that all the other stall prevention systems don't stop them from crashing the plane?

no
they are pretty good
you can see it in the development of the fatalities statistics of the last decades
actually they are brilliant

but they never had to control a transport category airplane with a flight behavior like a fighter jet if augmentation is switched off

a non functional AoA Sensor on a 737NG is pretty much a non event
it still flies like a eagle because its construction follows basical aerodynamical rules, applied in aviation since nearly a century, and if you have experience in handflying a plane you can bring that bird home without getting sweat

morrisond wrote:
So if a stall situation happens 1 in 100,000 flights (and I'm totally guessing here but I suspect it's a lot higher) and the pilots save it 99.99% - that's 1 in 1 Billion Flights. Assuming 10,000 MAX's flying and 50,000 Flights each that's about a 50% of an MAX stall resulting in an fatality in the life of the program.

i am not hot on finding out numbers
but if you really want to ...
if i think a utilisation of the 737MAX narrowbodies of 14hours a day
and if i think 5000 737MAXs worldwide
i count 70.000 flight hours a day and about 25.000.000 flight hours a year
if you suspect a stall situation every 250.000 hours that would mean 100 stalls a year

i think that a stall should be able to work off for 99,9% of our worldwide crews on a plane with a natural flight behaviour
what would leed to a stall accident once every ten years
bad enough ..

but the 737MAX does not has that "natural"behaviour
The pilot in the 737MAX can not use his previous flight experience in manual flight because the aircraft responds to his inputs differently than he is used to from other aircraft. No matter if he has learned his manual flight experience in a glider, in a GA plane or in many SIm flying hours, this flight feeling is not applicable in an airplane with abnormal flight behavior like the 737MAX.
and that can not be learned in an ipad course ...

so i would suspect a sucess rate (able to recover.. ) rather at 95-99% if no SIM training applied
what would bring us to a few yearly 737MAX crashes what hopefully god forbid ...

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 7:21 pm
by MrBretz
I just read somewhere that Boeing is going to have a quarterly dividend of just over $2/share. I can't wait to read what the pundits say about tomorrow's earning announcement.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 7:23 pm
by rheinwaldner
morrisond wrote:
So you are assuming the pilots are so bad or so poorly trained that all the other stall prevention systems don't stop them from crashing the plane?

Have you forgotten, that MCAS covers one aspect of stall prevention which is a certification requirement and which is not covered by the other stall prevention systems?

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 7:26 pm
by Northpole
I read somewhere in Swedish newspaper that Kevin McAllister has been sacked from Boeing

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 7:29 pm
by asdf
Northpole wrote:
I read somewhere in Swedish newspaper that Kevin McAllister has been sacked from Boeing


seems like ...

https://www.streetinsider.com/Corporate ... 34229.html

Boeing (BA) Announces Stan Deal to Succeed Kevin McAllister as CEO of Boeing Commercial Airplanes

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 7:43 pm
by Revelation
MrBretz wrote:
Tomorrow will be an interesting day. Boeing will report quarterly earnings. I wonder if it will be before the market opens or after it closes. I guess it could be any time.

I hope I can find the resulting discussion amidst all the discussion of stabilizer cutout switches, stick force, etc.

BTW in case no one has noticed, Boeing has released the fix package to FAA today.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 7:46 pm
by B777LRF
seahawk wrote:
Because shareholders and airlines have an interest to let the plane fly asap.


I'll let you in on a secret: There's no mechanism in EASA for considering the well-being of shareholders.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 7:51 pm
by Revelation
asdf wrote:
Northpole wrote:
I read somewhere in Swedish newspaper that Kevin McAllister has been sacked from Boeing


seems like ...

https://www.streetinsider.com/Corporate ... 34229.html

Boeing (BA) Announces Stan Deal to Succeed Kevin McAllister as CEO of Boeing Commercial Airplanes

NYT ( https://www.nytimes.com/2019/10/22/busi ... ister.html ) and WSJ ( https://www.wsj.com/articles/boeing-com ... 1571772010) suggest that his uneven handling of customer relationships got him the sack.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 7:56 pm
by PixelFlight
morrisond wrote:
PixelFlight wrote:
morrisond wrote:
As they were flying at full thrust at over Vmo - well above normal operating speed and the speed limit below 10,000' - it's as bad as no thrust and below stall speed - the trim wheel isn't going to help much there either.

You still don't get the fact that Vmo is just an arbitrary safety margin below the much higher design speed. The trim wheels must be usable up to the design speed, not just up to Vmo. And the difficulty to move the wheels was also probably linked to the extreme miss-trim induced by the MCAS. There are still the question why the pilots can't easily fully neutralize the stab trim (i have proposed two responses).


So what is the "Design speed" and please list the Regulation where the trim wheels have to be usable above Vmo.


Ask Boeing for there design speed. Vmo can be exceeded during flight tests. This is used to define safety margins and assess a Vmo which can be safely exceeded accidentally. The horizontal stabilizer is one of the most safety critical control surface, so it's clear that it have to be usable above Vmo, up to the safety margin, to recover the flight in any non-normal conditions, including failure of the only electrical stab trim actuator. And that mean with the trim wheels on a 737. I am curious to read how the 737 certification handle that point, and I expect the JT610 report to dig on it.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 8:09 pm
by SunsetLimited
Revelation wrote:
MrBretz wrote:
Tomorrow will be an interesting day. Boeing will report quarterly earnings. I wonder if it will be before the market opens or after it closes. I guess it could be any time.

I hope I can find the resulting discussion amidst all the discussion of stabilizer cutout switches, stick force, etc.

BTW in case no one has noticed, Boeing has released the fix package to FAA today.


Just curious, where did you find news about the submitted fix? Great step in the right direction , if true.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 8:19 pm
by Revelation
keesje wrote:
Agree, big cooperations love to concentrate problems at individuals & remove them (well paid if required).
It's quicker and easier than reviewing soft topics like "culture" and "strategy" and line of command.

Perhaps you've missed a few exciting announcements?

Governance and Oversight: A specially-appointed Board Committee conducted a rigorous, five-month independent review of the company’s policies and processes and made a series of recommendations that have been adopted. Earlier this month, the company also announced that its Board of Directors has separated the roles of chairman and chief executive officer to enable Boeing President and CEO Dennis Muilenburg to sharpen his focus full time on running the company, delivering on our customer commitments, and strengthening our focus on product and services safety.
Safety Management & Engineering Focus: On Sept. 30, Boeing announced the formation of a Product and Services Safety organization that will review all aspects of product safety and maintain oversight of our Accident Investigation Team and the company’s safety review boards. The organization’s leader has been named and the team has already begun operating under its new format. Other changes made include realigning the engineering function, establishing a formal Design Requirements Program, enhancing our Continued Operation Safety Program, partnering with our airline customers on flight deck designs that continue to anticipate the needs of future pilot populations, and expanding the reach of our Boeing Safety Promotion Center.
Additional steps taken: Boeing has taken additional measures to increase its focus on operational excellence and strengthen how it manages safety across the company, its supply chain, and the broader aerospace community in an effort to advance global aviation safety. We have broadened the use of a comprehensive safety management system and safety review boards to standardize safety policy and share best practices, led by senior company leadership for enhanced visibility. We are expanding the use of our anonymous reporting system to encourage employees to keep bringing forward potential safety issues. Boeing is also taking additional measures to address the growing need for talent, especially pilots and maintenance technicians, by further investing in STEM education. And we are investing heavily in areas such as product design, future flight decks, infrastructure, regulation and new technologies.

Ref: https://leehamnews.com/2019/10/22/boein ... ings-call/

It seems these are steps in the right direction, especially with regard to the safety teams reporting to the Chief Engineer rather than product line management and having board level supervision.

SunsetLimited wrote:
Revelation wrote:
MrBretz wrote:
Tomorrow will be an interesting day. Boeing will report quarterly earnings. I wonder if it will be before the market opens or after it closes. I guess it could be any time.

I hope I can find the resulting discussion amidst all the discussion of stabilizer cutout switches, stick force, etc.

BTW in case no one has noticed, Boeing has released the fix package to FAA today.


Just curious, where did you find news about the submitted fix? Great step in the right direction , if true.

Just last page:

Revelation wrote:
TropicalSky wrote:
Looks like the FAA has started its review
https://www.reuters.com/article/us-ethi ... X11MM?il=0

Mark October 22nd on your calendars:

Dickson said at a conference of air traffic controllers in Washington that the agency had received the “final software load” and “complete system description” of revisions to the plane, which was grounded in March after two fatal crashes.

Yet:

“It is going to be several more weeks before we go through all of that part of the process,” Dickson said. “We’ve got considerable work to do.”

If all goes well "mid Q4" will be missed by a few weeks, but global ungrounding in early 2020 is a plausible outcome given various recent statements.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 8:23 pm
by ShamrockBoi330
SunsetLimited wrote:
Revelation wrote:
MrBretz wrote:
Tomorrow will be an interesting day. Boeing will report quarterly earnings. I wonder if it will be before the market opens or after it closes. I guess it could be any time.

I hope I can find the resulting discussion amidst all the discussion of stabilizer cutout switches, stick force, etc.

BTW in case no one has noticed, Boeing has released the fix package to FAA today.


Just curious, where did you find news about the submitted fix? Great step in the right direction , if true.


yyp, its true... have read it many places now! After yesterdays announcement by EASA that they will loft Q120 earliest, FAA came out today announcing the final load has been received, along with a 500ish page doc to sift through explauning technical changes and updates.

https://www.reuters.com/article/us-ethi ... SKBN1X11MM

Dickson said at a conference of air traffic controllers in Washington that the agency had received the "final software load" and "complete system description" of revisions to the plane, which was grounded in March.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 8:30 pm
by keesje
Replacing people, no doubt with generous compensations, is ok as a signal.

The fundamentals, shareholder value, option based magement compensation packages, quaterly free cash flow targets, the close allignment with congress, wrecking the safety culture, what is going to change there?

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 8:35 pm
by MrBretz
I am planning a trip next February from CA to Florida, most likely on UA. I was just informed by my "other half" that I will be traveling alone if I book on a MAX. I have to say it would give me pause to fly on one. And I have to add, I trust the FAA will do the right thing. No one can afford another accident caused by the MCAS. If it were a year or so after RTS and there had been no accidents, I wouldn't have a problem. After all, we flew on many DC-10s after the AA crash.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 8:40 pm
by gregpodpl
lowbank wrote:
I will be clear, I want the MAX back in the air as soon as those given the job of judging it’s safe agree it is.
Not before.

"those given the job of judging it’s safe" - are those the same ones who had this job before?

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 8:55 pm
by PW100
morrisond wrote:
Amiga500 wrote:
planecane wrote:
I really hope you aren't a pilot. Use some common sense. If the same thing keeps happening over and over again and the thing that keeps happening is an abnormal amount of nose down trim it should be clear that there is a problem with the trim system.

OK, so now you are saying it should be possible to diagnose after several repeated MCAS interventions?
Right.

So if, say, the pilots on ET302 were to engage the cut-off switches after several MCAS activations - but then found they couldn't reverse the stabliser with the manual trim wheel due to adverse loading - so had to reengage the electric trim in an effort to get some authority on stabilizer...

As they were flying at full thrust at over Vmo - well above normal operating speed and the speed limit below 10,000' - it's as bad as no thrust and below stall speed - the trim wheel isn't going to help much there either.


You keep being economical with the facts . . .

When MCAS became alive, their speed was around 250 kts at 8000 ft pressure alt (05:40:00 in the FDR chart)
Vmo was around 340 kts at those conditions.

THEY WERE WAY BELOW VMO, before MCAS run-away.


If you study the FDR chart further, you will notice that just before MCAS came alive, two nose-up actions were initiated by the crew: short ANU electric trim, and aft column input. This suggests that they had been building speed by keeping a fairly shallow climb profile. As they hit 250 kts, they put in aft column (climb) and ANU trim (climb).

So it very much seems their game plan to handle the problems in hand (Stick Shaker/Stall Warning/Master Caution Ant-Ice/Unreliable Air Speed) was to build speed (250 kts) at the expense of shallower climb, and then increase rate of climb to maintain speed around 250 kts.

Just at that point when they seem to be changing over from “gaining speed” to “gaining altitude” MCAS hit them full in the face. MCAS could not have chosen any worse moment to put the aircraft in an out-of-trim situation. In just 9 seconds they went from having control over a non-standard (but non-event situation), to finding themselves fighting a severly out-of-trim situation, unable to put it back in trim.

It seems from that point on, their biggest/only concern was to try to stop the plane from diving into the ground. One could also add, that normal stable airplane behaviour is to raise the nose with increasing speed. I think they never realized how their speed was preventing them from doing just that.



Cut Out Switches:
While it is believed a crew should act within 4 seconds to a runaway trim, the first MCAS cycle went totally unanswered by the ET crew in terms of electric trim and cut-out switches.
The same thing can also been seen on the JT accident flight, and likely also with the JT pre-accident flight (though this one the FDR data does not provide sufficient resolution to state such as fact).

It seems the 4 second reaction time is not realistic.


If crews were supposed to react within 4 seconds of a stabilizer run-away, then surely they should also react within 4 seconds to an MCAS activation (valid or bogus),as there is no way for them to distinguish between MCAS run-away and “real trim runaway”.
But hitting the cut-out switches within 4 seconds after MCAS activation, destroys a great deal of the intention of MCAS

So, according to Boeing procedures, MCAS should then never ever reach its intended 9 second cycle if crews are following procedures (kill stabilizer trim within 4 seconds at run-away).

This is a catch 22 situation, as MCAS will not be able to perform its intended function, if crews follow the published procedure of hitting cut-out switches within 3 or 4 seconds of a stabilizer trim runaway. But if they allow MCAS to do its thing for full 9 seconds, they will find the plane in a severly out-of-trim situation.

I wonder how MCAS 2.0 deals with this situation.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 9:01 pm
by IADFCO
morrisond wrote:

Why do you think the stick force goes into the negative? I don't think there are any reports anywhere that that happens.

So you are assuming the pilots are so bad or so poorly trained that all the other stall prevention systems don't stop them from crashing the plane? Even if they ignore all the warnings and do stall it (99 out of 100 shouldn't get to this point) - there basic training should take over and 99% of them should be able to recover.

You must think that the worldwide training system is radically even poorer than I do.

So if a stall situation happens 1 in 100,000 flights (and I'm totally guessing here but I suspect it's a lot higher) and the pilots save it 99.99% - that's 1 in 1 Billion Flights. Assuming 10,000 MAX's flying and 50,000 Flights each that's about a 50% of an MAX stall resulting in an fatality in the life of the program.

About the same as the NG - see ET409.

BTW recurrent stall training is now a requirement in the sims in the US.


You don't know what the stall characteristics of the MAX are, whether they are similar to the NG or different.

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 9:39 pm
by sgrow787
frmrCapCadet wrote:
The 'expose' of the two pilots and their messages was an inadvertent but classic 'red herring'. That is, it was a side issue on building the software for the simulator, not the actual MAX. The original exposes did not make this clear, and in factual error said it was a MAX issue. And the inadvertent 'lie' seems to be a timeline issue. Forkner had told the FAA that MCAS had certain characteristic at one point, and some time later learned it had been changed. It is not known whether he corrected himself and so advised the FAA or even if he was required to.

Res pleading the 5th. If I have this correctly, you cannot partially answer a question by giving evidence that supports your position, and then plead the 5th on evidence against you. You need to be ready to 'tell the truth, the whole truth, and nothing but the truth', or just shut up about the whole thing.


Boeing wouldnt be doing simulator design 4 months before certification flight. On the contrary, they already qualified NG simulator would have been heavily borrowed from to create their Max sim. This is nothing but a last ditch effort by Boeing to steer away from impending accountability. T - 7 days and counting...

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Posted: Tue Oct 22, 2019 9:44 pm
by ikramerica
morrisond wrote:
asdf wrote:
Amiga500 wrote:
More to the point -
1. if the trim wheel spins for 3 seconds.
2. then the crew intervene and correct with trim switches.
3. MCAS cuts out for ~5 seconds (IIRC), so stabilizer stops trimming
4. which is then not in any way similar to how runaway stabilizer presents itself.


from my knowledge .... you can not expect an airline crew to react within 4 seconds with the appropiate action
not even to a memory item

if trim spin is normal
trim spin up to 3 seconds

at the 4th second the crew has to
- rethink if its really been three seconds or more
- give it another second (maybe we didnt realized..)
- determine if something else is not OK with the plane
- check back with the other pilot that something is going on with the trim
- deside if there is a somewhat normal explanation to it or if it is a situation to intervene
- grab the collumne and pull back to stop trim
- remember the ipad course a year ago that pulling back the colume does not stop trimming
- try the cut-out switches and find out that they are renamed and regrouped now on another position

...

IF at this stage at least 4 seconds have passed by, then the MCAS trim has stopped in the meantime ...

maybe a lot to think about what has happend
but nothing to do if you follow the procedures and you are not a clairvoyant


Please show in the Lionair or ET flights they only had 4 seconds to save the plane. They had minutes to figure it out.

At the end, where they had already completely lost the plot due ti the aggressive actions of MCAS and failure to disable autotrim per checklist (regardless of reason), they only had seconds.

While wildly different cause, that’s like saying the air france crew only had mere seconds to recover after spending all that time putting the aircraft into a really bad place.

What I find interesting is nobody talks much anymore about how JT and ET crashed after what attempting unstable turn backs when in neither case was it necessary to turn back at that time. Was it completely coincidental that they turned into the ground, data anomaly from final seconds of stall, or a panic move before they had figured out how to stably fly in a straight line.