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zeke
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 6:06 pm

L1049L1011 wrote:
Thanks for the great explanation! I've wondered why MCAS might be required during steep turns:


A stall can occur at any airspeed and in any aircraft attitude. When in a turn the load factor increases, the load factor in a level turn is equal to [1/cos(angle of bank)], the stall speed in the level turn will
Increase by the square root of the load factor. A 60 degree angle of bank level turn, the load factor would be 2 (2g) the stall speed would be around 40% higher (sqrt(2)) that when wings level. The interesting part is the stall will occur essentially at the same angle of attack.
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xmp125a
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 6:07 pm

uta999 wrote:
Could MCAS not have AGL and terrain added to its criteria? so it does not kick in at all, if so near the ground that pointing the nose down defeats any form of stall protection.

There’s little point in MCAS ‘saving’ a plane from a stall, when it’s heading into the ground or terrain.


Stall is extremely dangerous condition - it essentially means, that the plane is not flying at all and you are dead at 1000ft AGL. So, at 1000ft AGL the system which PREVENTS stall from happening is still very reasonable - if you pitch nose too far up at 1000ft AGL a system that merely trims the plane (goes from pitch up to level flight) may rescue the plane as well!

The core issue with MCAS is its dependence on fallible sensor AND the absence of "MCAS off" switch (besides trim motor off switch). Neither Ethiopian nor LionAir were not close in stall conditions and yet MCAS activated; activating when not close to stall even at 20000ft AGL is something that should not happen.

So no, AGL condition would merely add another patch to the whole patchwork that is MCAS itself.
 
OB1504
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 6:11 pm

spinotter wrote:
MSPNWA wrote:
RossW wrote:
A good video for the average Joe

https://youtu.be/H2tuKiiznsY


If the Average Joe wishes to be misinformed, yes, it's a good video.


I did not watch the video, but I do know that someone who states: "If the AverageJoe wishes to be misinformed" - that person has an agenda.


Another poster commented that the video is bad because it didn’t say the crashes were all the pilots’ fault and that Boeing did nothing wrong.

It amazes me that people would rather let a potentially unsafe aircraft fly than admit that Boeing made a mistake.
 
MSPNWA
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 7:01 pm

spinotter wrote:
I did not watch the video, but I do know that someone who states: "If the AverageJoe wishes to be misinformed" - that person has an agenda.


I do have an "agenda"--point people towards facts and flag misinformation. If you have a problem with that "agenda", it reveals one of your own.
 
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bgm
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 7:09 pm

MSPNWA wrote:
spinotter wrote:
I did not watch the video, but I do know that someone who states: "If the AverageJoe wishes to be misinformed" - that person has an agenda.


I do have an "agenda"--point people towards facts and flag misinformation. If you have a problem with that "agenda", it reveals one of your own.


So tell us then, what parts of that video were factually incorrect?

And please, don’t lecture us about agendas. Just look at any of your Delta related posts to see the agenda you’re peddling. :sarcastic:
Really? Four more years of this?
 
Jamie514
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 7:19 pm

MSPNWA wrote:
spinotter wrote:
I did not watch the video, but I do know that someone who states: "If the AverageJoe wishes to be misinformed" - that person has an agenda.


I do have an "agenda"--point people towards facts and flag misinformation. If you have a problem with that "agenda", it reveals one of your own.


Please then, without bias, do provide any available evidence of the misinformation you have several times now alleged takes place in the video. it is a typical requirement of the forum at this point in either advancing ones argument or else retracting it.

Mods, please do not delete this post, it is compliant with all forum rules.
 
hivue
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 8:02 pm

xmp125a wrote:
Neither Ethiopian nor LionAir were not close in stall conditions and yet MCAS activated;


This is getting a little weird -- like two ships passing in thick fog. Some posters keep insisting that MCAS is an anti-stall system. Others simultaneously are waving their arms wondering where in the "average Joe" video -- the one that strongly implies that MCAS is an anti-stall system -- the misinformation is. The resolution to all this confusion is understanding that MCAS is not an anti-stall system.
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kalvado
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 8:11 pm

hivue wrote:
xmp125a wrote:
Neither Ethiopian nor LionAir were not close in stall conditions and yet MCAS activated;


This is getting a little weird -- like two ships passing in thick fog. Some posters keep insisting that MCAS is an anti-stall system. Others simultaneously are waving their arms wondering where in the "average Joe" video -- the one that strongly implies that MCAS is an anti-stall system -- the misinformation is. The resolution to all this confusion is understanding that MCAS is not an anti-stall system.

It is not an anti-stall, but it is designed to reduce possibility of entering the stall and is needed as part of stall related regulations. It looks like a duck, swims like a duck, and quacks like a duck, but is actually a goose...
 
morrisond
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 8:20 pm

It seems like the Video Pilot got his information from this article https://aviationweek.com/commercial-avi ... lator-demo

Lots of good info - the part about the US pilots never being trained on AOA failures a little scary but not surprising given the current low state of training.

"Pilots for three U.S. air carriers tell Aviation Week that during their sim training they had never been exposed to extreme and continuous AOA indication errors, they’ve not experienced AOA induced airspeed and altitude deviations on PFDs and have not had to deal with continuous stall-warning stickshaker distractions. They also note that they have never been required to fly the aircraft from the point at which a runaway stab trim incident occurred all the way to landing using only the manual trim wheels. “We’re just checking boxes for the FAA,” says one Seattle-based pilot."
 
oschkosch
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 8:30 pm

https://www.reuters.com/article/us-ethi ... SKCN1RS1ZR


A Federal Aviation Administration review board said on Tuesday a software update to the grounded Boeing 737 MAX aircraft was found to be “operationally suitable,” suggesting the lengthy regulatory process to get the planes back in the air was well underway


https://www.bnnbloomberg.ca/faa-board-s ... -1.1245438


A board of pilot experts appointed by U.S. aviation regulators has reviewed Boeing Co.’s proposed software fix for the grounded 737 Max aircraft and concluded that pilots won’t need additional simulator training once the plane is returned to service.
The report by a Federal Aviation Administration Flight Standardization Board is an important first step in reviewing the still-unfinished upgrade to the 737 Max family of aircraft. It was posted on the FAA’s website and the public has until April 30 to make comments.
The proposal calls for stepped up training on the anti-stall system called MCAS that is linked to two fatal crashes, but stops short of requiring costly simulator training that could complicate the plane’s return to service.




My view: Business seems more vital than safety.....I hope the Chinese and EU have a closer look than the FAA....

https://www.caixinglobal.com/2019-04-17 ... 05015.html






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oschkosch
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 8:36 pm

FAA draft available here:

https://www.faa.gov/aircraft/draft_docs ... _draft.pdf



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:stirthepot: :airplane: "This airplane is designed by clowns, who in turn are supervised by monkeys" :airplane: :stirthepot:
 
MSPNWA
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 8:53 pm

Jamie514 wrote:
Please then, without bias, do provide any available evidence of the misinformation you have several times now alleged takes place in the video. it is a typical requirement of the forum at this point in either advancing ones argument or else retracting it.

Mods, please do not delete this post, it is compliant with all forum rules.


Not to pick on you, but I always find it amusing that a person can post a video, and automatically it is credible - the audience has to refute it. And not only that, but the audience has an "agenda", and not the video itself. But I digress.

Since you asked, here's the claims starting at the 3 minute mark that immediately told me it was not a video to watch:

1) When the Max is at full thrust, like at takeoff, the nose tends to pitch too far upward --- this is highly misleading at best, a lie at worst. It's a wild statement that is not corroborated any source. In fact, if it is true, it implies the MAX is an airplane that is not controlled by the control surfaces but by the engines, as it pitches up on its own under high power. So we know this is a wrong statement. The known issue (larger nacelles forward of CoG) isn't dependent on engine thrust either. The angle of attack is the key factor.

2) The planes are supposed to fly exactly like the NG --- again highly misleading at best. The MCAS requirement is best explained by the source of it - it is to comply with the requirement that the stick forces are linear (no "lightening" at high AOA). Common type ratings - which is probably the "problem" the video is trying to get at - don't require they fly "exactly the same".

3) Boeing created a "workaround" instead re-engineering the plane --- sensationalist language that isn't the cause of a poor MCAS design and implementation. Boeing didn't need to re-engineer the airplane to do this right.

4) The video states that several pilots said their Max nosed down suddenly --- they've been talked before in these threads. They're undocumented, anonymous reports stated as factual, documented events. This is not mentioned and will easily mislead viewers.

There's more I could pick it, but in just one minute I've been fed a host of misleading or inaccurate information. You bet there's an agenda out there.
Last edited by MSPNWA on Tue Apr 16, 2019 8:59 pm, edited 1 time in total.
 
kalvado
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 8:54 pm

oschkosch wrote:
FAA draft available here:

https://www.faa.gov/aircraft/draft_docs ... _draft.pdf



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would be interesting to see if FAA review just the small piece, or there is also a review of what led to mistakes in failure tree analysis and a criticallook back?
 
AvFanNJ
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 9:03 pm

MSPNWA wrote:
Jamie514 wrote:
Please then, without bias, do provide any available evidence of the misinformation you have several times now alleged takes place in the video. it is a typical requirement of the forum at this point in either advancing ones argument or else retracting it.

Mods, please do not delete this post, it is compliant with all forum rules.


Not to pick on you, but I always find it amusing that a person can post a video, and automatically it is credible - the audience has to refute it. And not only that, but the audience has an "agenda", and not the video itself. But I digress.

Since you asked, here's the claims starting at the 3 minute mark that immediately told me it was not a video to watch:

1) When the Max is at full thrust, like at takeoff, the nose tends to pitch too far upward --- this is highly misleading at best, a lie at worst. It's a wild statement that is not corroborated any source. In fact, if it is true, it implies the MAX is an airplane that is not controlled by the control surfaces but by the engines, as it pitches up on its own under high power. So we know this is a wrong statement. The known issue (larger nacelles forward of CoG) isn't dependent on engine thrust either. The angle of attack is the key factor.

2) The planes are supposed to fly exactly like the NG --- again highly misleading at best. The MCAS requirement is best explained by the source of it - it is to comply with the requirement that the stick forces are linear (no "lightening" at high AOA). Common type ratings - which is probably the "problem" the video is trying to get at - don't require they fly "exactly the same".

3) Boeing created a "workaround" instead re-engineering the plane --- sensationalist language that isn't the cause of a poor MCAS design and implementation. Boeing didn't need to re-engineer the airplane to do this right.

4) The video states that several pilots said their Max nosed down suddenly --- they've been talked before in these threads. They're undocumented, anonymous reports stated as factual, documented events. This is not mentioned and will easily mislead viewers.

There's more I could pick it, but in just one minute I've been fed a host of misleading or inaccurate information. You bet there's an agenda out there.

I agree with your critique of that video and found it also to be too simplistic. I found this one to be more informative and explanatory: https://www.youtube.com/watch?v=zGM0V7zEKEQ
 
morrisond
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 9:40 pm

AvFanNJ wrote:
MSPNWA wrote:
Jamie514 wrote:
Please then, without bias, do provide any available evidence of the misinformation you have several times now alleged takes place in the video. it is a typical requirement of the forum at this point in either advancing ones argument or else retracting it.

Mods, please do not delete this post, it is compliant with all forum rules.


Not to pick on you, but I always find it amusing that a person can post a video, and automatically it is credible - the audience has to refute it. And not only that, but the audience has an "agenda", and not the video itself. But I digress.

Since you asked, here's the claims starting at the 3 minute mark that immediately told me it was not a video to watch:

1) When the Max is at full thrust, like at takeoff, the nose tends to pitch too far upward --- this is highly misleading at best, a lie at worst. It's a wild statement that is not corroborated any source. In fact, if it is true, it implies the MAX is an airplane that is not controlled by the control surfaces but by the engines, as it pitches up on its own under high power. So we know this is a wrong statement. The known issue (larger nacelles forward of CoG) isn't dependent on engine thrust either. The angle of attack is the key factor.

2) The planes are supposed to fly exactly like the NG --- again highly misleading at best. The MCAS requirement is best explained by the source of it - it is to comply with the requirement that the stick forces are linear (no "lightening" at high AOA). Common type ratings - which is probably the "problem" the video is trying to get at - don't require they fly "exactly the same".

3) Boeing created a "workaround" instead re-engineering the plane --- sensationalist language that isn't the cause of a poor MCAS design and implementation. Boeing didn't need to re-engineer the airplane to do this right.

4) The video states that several pilots said their Max nosed down suddenly --- they've been talked before in these threads. They're undocumented, anonymous reports stated as factual, documented events. This is not mentioned and will easily mislead viewers.

There's more I could pick it, but in just one minute I've been fed a host of misleading or inaccurate information. You bet there's an agenda out there.

I agree with your critique of that video and found it also to be too simplistic. I found this one to be more informative and explanatory: https://www.youtube.com/watch?v=zGM0V7zEKEQ


That's the Video I was referring too that seems to get its info from the Avweek article. Sorry I didn't click on the link and made a bad assumption.
 
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Revelation
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 10:54 pm

oschkosch wrote:
https://www.bnnbloomberg.ca/faa-board-s ... -1.1245438

A board of pilot experts appointed by U.S. aviation regulators has reviewed Boeing Co.’s proposed software fix for the grounded 737 Max aircraft and concluded that pilots won’t need additional simulator training once the plane is returned to service.

I think I hear the sound of a.net reader's heads exploding.

The obvious next question is: will other "board of pilot experts" NOT "appointed by U.S. aviation regulators" reach the same conclusion?

And if they do, will even more a.net reader's heads explode?

And if they don't, will ugly political squabbles erupt?
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Vladex
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Re: B737MAX Grounded Worldwide

Tue Apr 16, 2019 10:58 pm

If I try to understand the essence of this, the intention is to have more MCAS sensors to initiate more MCAS activations but then to have MCAS be quickly shut off as it pitches the nose down. . Or if the intentions is that different sensors check and cancel each other out , then when sensors activate MCAS , it should be cancelled out anyway as it pitches the nose down again.

That seems like pushing the design in two directions, either MCAS is the last resort or it's a standard routine feature, either it's balancing the airplane or it's pushing it down, either it's making it have the feel of other 737's or it doesn't , either it can be turned off or it can't . Just what is the thinking here in layman terms? Software fix is how they got here
 
kalvado
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 1:23 am

Revelation wrote:
oschkosch wrote:
https://www.bnnbloomberg.ca/faa-board-s ... -1.1245438

A board of pilot experts appointed by U.S. aviation regulators has reviewed Boeing Co.’s proposed software fix for the grounded 737 Max aircraft and concluded that pilots won’t need additional simulator training once the plane is returned to service.

I think I hear the sound of a.net reader's heads exploding.

The obvious next question is: will other "board of pilot experts" NOT "appointed by U.S. aviation regulators" reach the same conclusion?

And if they do, will even more a.net reader's heads explode?

And if they don't, will ugly political squabbles erupt?

I wouldn't be surprized if non-US panel will come to the same conclusion. Some extra training beyond 30 min presentation may be added; but still there are only that much differences.
Having somewhat different pilot ratings in different regulatory domains is nothing new, I believe A330/340/350 have some of that. As long as WN gets their wish..

Two real questions, though:
AoA disagree indicator - some believed it will require sim training (honestly speaking I don't quite understand that). How does that work after all?
How far did FAA go in patch review? My impression is that Boeing did everything to prevent MCAS activation, including situations when it is required. If that is the case, next MAX to fall out of the sky may do so due to stall...
 
Elementalism
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 2:03 am

Vladex wrote:
If I try to understand the essence of this, the intention is to have more MCAS sensors to initiate more MCAS activations but then to have MCAS be quickly shut off as it pitches the nose down. . Or if the intentions is that different sensors check and cancel each other out , then when sensors activate MCAS , it should be cancelled out anyway as it pitches the nose down again.

That seems like pushing the design in two directions, either MCAS is the last resort or it's a standard routine feature, either it's balancing the airplane or it's pushing it down, either it's making it have the feel of other 737's or it doesn't , either it can be turned off or it can't . Just what is the thinking here in layman terms? Software fix is how they got here


You are overthinking this. They are changing MCAS to include dual input from AOA sensors. They are also limiting its ability to push the trim to full deflection. At most the pilots will always have the ability to pull back on the yoke to overcome the system. If AOA sensors deviate by more than 5.5 degrees MCAS is turned off.
 
frmrCapCadet
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 2:07 am

And the world asks, "If it was so comparatively simple why didn't they do it the first time right?".
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BirdBrain
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 2:37 am

Looks like China has formed a task force to review the fix. Looks like a quick un-grounding is becoming a difficult target. EASA probably has their own team specifically looking into it.

https://ca.reuters.com/article/business ... S0ZY-OCABS
 
planecane
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 2:53 am

BirdBrain wrote:
Looks like China has formed a task force to review the fix. Looks like a quick un-grounding is becoming a difficult target. EASA probably has their own team specifically looking into it.

https://ca.reuters.com/article/business ... S0ZY-OCABS

It seems everything is pointing to the grounding lasting another 90 days. I don't think over 4 months best case is a quick ungrounding.
 
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DocLightning
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 2:57 am

jagraham wrote:
A mechanical system can do what FBW does, but it's usually heavier.
Besides the 737 MAX is partially FBW (ailerons, not tailplane)
https://www.intelligent-aerospace.com/a ... ments.html


MAX ailerons are mechanical. The spoilers are FBW.

Elementalism wrote:
You are overthinking this. They are changing MCAS to include dual input from AOA sensors. They are also limiting its ability to push the trim to full deflection.


That raises the question: why was it necessary to allow the MCAS to push the trim to full deflection in the first place? Are we going to find that 737NG pilots are inadequately trained to recover from a potential stall at high AOA because the new MCAS doesn't have enough authority? Boeing had better be very certain that won't happen, because if that happens and a 737 flies tail-first into the ground, the 737MAX will be decertified permanently.
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planecane
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 3:09 am

DocLightning wrote:


Elementalism wrote:
You are overthinking this. They are changing MCAS to include dual input from AOA sensors. They are also limiting its ability to push the trim to full deflection.


That raises the question: why was it necessary to allow the MCAS to push the trim to full deflection in the first place? Are we going to find that 737NG pilots are inadequately trained to recover from a potential stall at high AOA because the new MCAS doesn't have enough authority? Boeing had better be very certain that won't happen, because if that happens and a 737 flies tail-first into the ground, the 737MAX will be decertified permanently.

It wasn't necessary or intended for MCAS to push the trim to full deflection. The original design was for it to push nose down 0.6 degrees. Flight testing determined that, in some situations, 2.5 degrees was necessary. Part of the poorly thought out algorithm was that it didn't stop at the maximum necessary trim.

There is no situation where the aircraft can still have a too high AoA after the 2.5 degree AND trim. The algorithm was "dumb" and would see the AoA sensor still reading high and activate again. It didn't "know" that the aircraft couldn't possibly still be in that pitch attitude.
 
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seahawk
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 4:51 am

Revelation wrote:
oschkosch wrote:
https://www.bnnbloomberg.ca/faa-board-s ... -1.1245438

A board of pilot experts appointed by U.S. aviation regulators has reviewed Boeing Co.’s proposed software fix for the grounded 737 Max aircraft and concluded that pilots won’t need additional simulator training once the plane is returned to service.

I think I hear the sound of a.net reader's heads exploding.

The obvious next question is: will other "board of pilot experts" NOT "appointed by U.S. aviation regulators" reach the same conclusion?

And if they do, will even more a.net reader's heads explode?

And if they don't, will ugly political squabbles erupt?


Why should heads explode?

A software fix that adds AoA disagree warnings, might consider the airspeed and uses both sensors in addition to the changed activation logic always seemed enough. The rest was hysteria. If MCAS auto deactivates in case of an AoA disagree situation, you do not even need an extra switch to turn it off.
 
RickNRoll
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 6:05 am

MD80Ttail wrote:
xmp125a wrote:
seahawk wrote:

We will see if this changes anything, because it would need a complete reversal of the FAA´s company culture, that sees EASA or CAA as lesser entities that are only trying to help the manufacturers in their countries. And Boeing will be adding fuel to the fire already.


It really is simple. If FAA goes solo with un-grounding the planes, against opinions of other panel members, then 737MAX won't be able to enter any airspace other than US. This would be a death knell for 737MAX, and perhaps Boeing as well (which would, no doubt, be kept afloat by government loans or takeover).

But it would really make the situation so much worse for Boeing that we can safely assume this will not happen.


Zero chance of this happening. The Max will fly again and be totally safe. The rest of the world won’t dare block the Max if the FAA reinstates it’s AW cert withdrawing the grounding. There will be plenty of hyperbole, chest pumping and positioning but at the end of the day will amount to nothing more than fodder for the news media.

On the face of it the MCAS issue will be solved and the plane will be safe. Period. On the backside politics if needed will come into play. Even China will pipe down if they want to keep sending their junk to the US without huge tariffs and if they want to avoid issues in the South China Sea.

Boeing is integral to our economy and national defense and rightly so.
That's not the right message to be sending to the rest of the world.
 
L1049L1011
Posts: 18
Joined: Tue Sep 06, 2016 6:54 pm

Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 6:34 am

oschkosch wrote:
FAA draft available here:

https://www.faa.gov/aircraft/draft_docs ... _draft.pdf



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Thanks. Seems to be word-by-word identical to the previous draft report dated March 26, 2019.
 
L1049L1011
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 6:53 am

zeke wrote:
L1049L1011 wrote:
Thanks for the great explanation! I've wondered why MCAS might be required during steep turns:


A stall can occur at any airspeed and in any aircraft attitude. When in a turn the load factor increases, the load factor in a level turn is equal to [1/cos(angle of bank)], the stall speed in the level turn will
Increase by the square root of the load factor. A 60 degree angle of bank level turn, the load factor would be 2 (2g) the stall speed would be around 40% higher (sqrt(2)) that when wings level. The interesting part is the stall will occur essentially at the same angle of attack.

Thanks! It's always nice and helpful to read some physics and hard facts amid all the speculations and half-informed guess work!
 
xmp125a
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 7:02 am

hivue wrote:
xmp125a wrote:
Neither Ethiopian nor LionAir were not close in stall conditions and yet MCAS activated;


This is getting a little weird -- like two ships passing in thick fog. Some posters keep insisting that MCAS is an anti-stall system. Others simultaneously are waving their arms wondering where in the "average Joe" video -- the one that strongly implies that MCAS is an anti-stall system -- the misinformation is. The resolution to all this confusion is understanding that MCAS is not an anti-stall system.


I meant that it activated in conditions where there was no possibility of the stall, and it activated because of the sensor failure. It does not matter whether it is anti stall system or not if it tends to activate in level flight with engines almost to the maximum :)

The problem is not that the system is not doing what is supposed to do, the problem is it was doing what it wasn't supposed to do.
 
mjoelnir
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 7:10 am

seahawk wrote:
Revelation wrote:
oschkosch wrote:
https://www.bnnbloomberg.ca/faa-board-s ... -1.1245438

A board of pilot experts appointed by U.S. aviation regulators has reviewed Boeing Co.’s proposed software fix for the grounded 737 Max aircraft and concluded that pilots won’t need additional simulator training once the plane is returned to service.

I think I hear the sound of a.net reader's heads exploding.

The obvious next question is: will other "board of pilot experts" NOT "appointed by U.S. aviation regulators" reach the same conclusion?

And if they do, will even more a.net reader's heads explode?

And if they don't, will ugly political squabbles erupt?


Why should heads explode?

A software fix that adds AoA disagree warnings, might consider the airspeed and uses both sensors in addition to the changed activation logic always seemed enough. The rest was hysteria. If MCAS auto deactivates in case of an AoA disagree situation, you do not even need an extra switch to turn it off.


Because the emphasis is still on minimizing training cost, instead of maximizing safety.
 
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seahawk
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 7:28 am

mjoelnir wrote:
seahawk wrote:
Revelation wrote:
I think I hear the sound of a.net reader's heads exploding.

The obvious next question is: will other "board of pilot experts" NOT "appointed by U.S. aviation regulators" reach the same conclusion?

And if they do, will even more a.net reader's heads explode?

And if they don't, will ugly political squabbles erupt?


Why should heads explode?

A software fix that adds AoA disagree warnings, might consider the airspeed and uses both sensors in addition to the changed activation logic always seemed enough. The rest was hysteria. If MCAS auto deactivates in case of an AoA disagree situation, you do not even need an extra switch to turn it off.


Because the emphasis is still on minimizing training cost, instead of maximizing safety.


So you have seen the details of the fix?
 
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InsideMan
Posts: 353
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 7:55 am

OB1504 wrote:
spinotter wrote:
MSPNWA wrote:

If the Average Joe wishes to be misinformed, yes, it's a good video.


I did not watch the video, but I do know that someone who states: "If the AverageJoe wishes to be misinformed" - that person has an agenda.


Another poster commented that the video is bad because it didn’t say the crashes were all the pilots’ fault and that Boeing did nothing wrong.

It amazes me that people would rather let a potentially unsafe aircraft fly than admit that Boeing made a mistake.


What's wrong with the video is, that it says on the Ethiopian flight they disabled MCAS too late to regain control. This is not what happened.
Read the description by Bjoern Fehrm. Long story short, blowback prevented them from manual trimming the plane....
https://leehamnews.com/2019/03/22/bjorn ... sh-part-2/

Other than that it is quite good, considering
 
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sassiciai
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 8:11 am

I recently retired after a 40 year career in the "software industry". We ourselves called ourselves business change engineers, rather than
software developers.
It irritates me quite a lot to hear that the B737 MAX solution is just a software uodate. That sounds like it is delegated to a couple of fresh 22 year old coders, to come up with improved code. What's more, how do regulators check "software updates"? Code reviews? Oh yes!

MCAS is a system, and it must be defined in a set of detailed documents. Requirements Spec, Functional Spec, Design Spec, Test Specs for each of the preceding documents, a Quality Plan defining exactly to what standards the software will be designed, written, reviewed, and tested, including the process for fault resolution. A waterfall staging of these documents (how much software is already developed before the Requirements are revised, agreed, and put under configuration control). In my experience, a solution that is based on software devotes about 10% of its effort to making the "software update".

It could be that under commercial pressure, Boeing dropped the above methodology, wrote a requirements spec during a meeting on a white board, and then the 2 coders went to work, without the normal constraints of tight and layered documents defying what to achieve, and the second set of documents specifying the testing required to verify up from the code successively to the Requirements Spec. Somewhere on there, real flight tests would be called for

A software fix that might take 15 minutes of some hot programming guru with his own unique understanding of what's wanted must be resisted at all cost. In safety critcal situations, changes should follow the life cycle and avoid the tempting short cuts, these life cycles are based on experience, mostly from lessons learnt.

The regulators around the world should not focus on a "software update" as a changed module of code, rather on the full life cycle products, as developed, reviewed, and signed off by Boeing, including a particularly arduous set of flight tests to explore all corners as identified in the Risk Analysis carried out as part of the design phase.

Boeing's original plan to have a fix in 3 weeks is unfortunately so revealing as to which development path it had chosen. That would most likely have delivered source code as the document to review!
 
afgeneral
Posts: 136
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 8:16 am

maybe the MAX should keep flying exclusively in the US for a few years and only let it fly in EU / China after it has a proven safety record
 
AirwayBill
Posts: 181
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 8:35 am

afgeneral wrote:
maybe the MAX should keep flying exclusively in the US for a few years and only let it fly in EU / China after it has a proven safety record


Unfortunately it is unlikely to happen due to political pressure. But I agree, worldwide authorities shouln't take FAA/Boeing statements as gospel, and should ask for full transparency before committing to the solution or any possible ungrounding. It is not worth taking anymore risks with another bandaid fix, quite certainly developed to appease shareholders and customers worried for their short term profit, rather than provide a durable fix to a sick design.
 
asdf
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 8:36 am

MSPNWA wrote:
1) When the Max is at full thrust, like at takeoff, the nose tends to pitch too far upward --- this is highly misleading at best, a lie at worst. It's a wild statement that is not corroborated any source. In fact, if it is true, it implies the MAX is an airplane that is not controlled by the control surfaces but by the engines, as it pitches up on its own under high power. So we know this is a wrong statement.


well
this is simply said in the open public as long as no one can proof the opposite at this point


The test pilots who flew the aircraft before the approval recommended after the tests a much stronger intervention of MCAS than originally planned.
if we assume that the test pilots were professionals ... what can we conclude from this?

exactly

that the MAX's flow characteristics were far worse than expected due to the fact that the engines were mounted far ahead

as many details of the two crashes are still missing I would not exclude at this point that the MCAS has in reality only little to do with the crash
but the crews flew actually because of the - in comparison to a NG - unexpected and deficient flow characteristic of their ship in the steep turn into a simple stall
 
flybucky
Posts: 376
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 9:18 am

rideforever wrote:
flybucky wrote:
For both sensors failing at the same time, yes it is 0.2 * 0.2 = 0.04. But that it not relevant to MCAS failure.

This is not correct.
As the sensors are of identical manufacture and frequently fail due to climatic conditions ... then the probability is closer to 0.2

True. I was just giving the theoretical/simplistic independent probability calculation. But in reality, you are correct, it would be higher since they could fail simultaneously due to the same environmental conditions.
 
flybucky
Posts: 376
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 9:23 am

RobertS975 wrote:
Does a twin engine aircraft have a greater chance of an engine failure than a single engine aircraft? Yes, it does. But would you rather be aboard a twin engine aircraft that has an engine failure or would you rather be on a single engine aircraft with an engine failure?

That's a good analogy. Here's my preferences:

1. Twin engine aircraft that uses both engines.
2. Single engine aircraft.
3. Twin engine aircraft that can only use one engine per flight. (And cycles between engines each flight.)

Unfortunately, MCAS was #3.
Last edited by flybucky on Wed Apr 17, 2019 9:30 am, edited 1 time in total.
 
Amiga500
Posts: 2645
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 9:26 am

Revelation wrote:
oschkosch wrote:
https://www.bnnbloomberg.ca/faa-board-s ... -1.1245438

A board of pilot experts appointed by U.S. aviation regulators has reviewed Boeing Co.’s proposed software fix for the grounded 737 Max aircraft and concluded that pilots won’t need additional simulator training once the plane is returned to service.

I think I hear the sound of a.net reader's heads exploding.

The obvious next question is: will other "board of pilot experts" NOT "appointed by U.S. aviation regulators" reach the same conclusion?

And if they do, will even more a.net reader's heads explode?

And if they don't, will ugly political squabbles erupt?


Since when did pilots develop the capability to verify software, develop fault trees and evaluate failure cascades?

The media conception of the sky-gods having much understanding beyond the names on the switches and what they are supposed to make happen is a bit misleading.

Thankfully, the standardization board is made up of more than just pilots.


Given EASA wanted more training for the original MCAS - I would expect some degree of squabbling in the background before a final conclusion to this saga.

I also want to know whether there has been investigations on the effect of the manual trim being "effectively ineffective" and how this affects failure scenarios of the electronic trim. FAA might not ask that question, I would expect EASA or CAAC will.
 
flybucky
Posts: 376
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 9:29 am

XRAYretired wrote:
Yes, it was mea culpa.
http://www.b737.org.uk/mcas.htm
2.5 degrees in 9.26sec cycle = 0.27deg/sec. is the current design.
0.6 degrees in 9.26 sec cycle = 0.065deg/sec was the original design from reports.

I'm not sure if "0.6 degrees in 9.26 sec cycle = 0.065deg/sec was the original design" is true. I know that 0.6º per cycle was the original MCAS design, but are you assuming it was still over a 9.26s period? Or was it at the same 0.27º/s rate (which would be over a period of 2.22 seconds)?
 
mjoelnir
Posts: 9386
Joined: Sun Feb 03, 2013 11:06 pm

Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 9:38 am

seahawk wrote:
mjoelnir wrote:
seahawk wrote:

Why should heads explode?

A software fix that adds AoA disagree warnings, might consider the airspeed and uses both sensors in addition to the changed activation logic always seemed enough. The rest was hysteria. If MCAS auto deactivates in case of an AoA disagree situation, you do not even need an extra switch to turn it off.


Because the emphasis is still on minimizing training cost, instead of maximizing safety.


So you have seen the details of the fix?


https://www.bnnbloomberg.ca/faa-board-s ... -1.1245438

Perhaps you start reading that article, that was presented in the post you answered to and asked why heads should explode.

The news was about no mandatory simulator time on a 737MAX simulator. Still an I-pad only difference training.

Emphasis on the cost off training over safety. As the situation is now, neither Boeing nor the FAA should even try shortcuts

I assume one of the reasons for this shortcut could be, that no USA airline had invested into 737MAX simulators. They have very few simulators on order and are still waiting for them. Mandatory simulator training included in the difference training, would mean that no USA airline would have pilots ready in the near future.
So if the 737MAX should get her recertification soon, there would be no certified pilots to fly them in the USA.
Last edited by mjoelnir on Wed Apr 17, 2019 9:44 am, edited 1 time in total.
 
User avatar
seahawk
Posts: 9645
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 9:41 am

mjoelnir wrote:
seahawk wrote:
mjoelnir wrote:

Because the emphasis is still on minimizing training cost, instead of maximizing safety.


So you have seen the details of the fix?


The news was about no mandatory simulator time on a 737MAX simulator. Still an I-pad only difference training.

I assume one of the reasons could be, that no USA airline had invested into 737MAX simulators. They have very few simulators on order and are still waiting for them. Mandatory simulator training included in the difference training, would mean that no USA airline would have pilots ready in the near future.
So if the 737MAX should get her recertification soon, there would be no certified pilots to fly them.


So you already know that simulator training would be needed even after the fix was installed?
 
art
Posts: 3453
Joined: Tue Feb 08, 2005 11:46 am

Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 9:47 am

AirwayBill wrote:
...worldwide authorities shouln't take FAA/Boeing statements as gospel, and should ask for full transparency before committing to the solution or any possible ungrounding. It is not worth taking anymore risks with another bandaid fix, quite certainly developed to appease shareholders and customers worried for their short term profit, rather than provide a durable fix to a sick design.


:checkmark:
 
mjoelnir
Posts: 9386
Joined: Sun Feb 03, 2013 11:06 pm

Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 9:49 am

seahawk wrote:
mjoelnir wrote:
seahawk wrote:

So you have seen the details of the fix?


The news was about no mandatory simulator time on a 737MAX simulator. Still an I-pad only difference training.

I assume one of the reasons could be, that no USA airline had invested into 737MAX simulators. They have very few simulators on order and are still waiting for them. Mandatory simulator training included in the difference training, would mean that no USA airline would have pilots ready in the near future.
So if the 737MAX should get her recertification soon, there would be no certified pilots to fly them.


So you already know that simulator training would be needed even after the fix was installed?


Yes, if you do not want unnecessary risks. The emphasis on no simulator training and sabotaging that useful simulators, that could show MCAS failure conditions, could be bought, is part of the reason that 350 people got killed.
 
flybucky
Posts: 376
Joined: Tue Apr 17, 2018 7:44 pm

Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 9:54 am

InsideMan wrote:
Read the description by Bjoern Fehrm. Long story short, blowback prevented them from manual trimming the plane....
https://leehamnews.com/2019/03/22/bjorn ... sh-part-2/

No, Bjorn is saying blowback prevented the yoke/elevators from overcoming the full nose down of the stabilizers during the final dive.

"The cause of the final dive has bugged me since the Flight Data Recorder (FDR) traces from JT601 were released. I couldn’t find a plausible answer. I tried different theories but none was convincing... Blowback means the elevator is gradually blown back to lower and lower elevation angles by the pressure of the air as the speed increases. "

What probably prevented the manual wheel trim was the nose down load on the stabilizer: https://www.satcom.guru/2019/04/stabili ... range.html
 
XRAYretired
Posts: 870
Joined: Fri Mar 15, 2019 11:21 am

Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 10:06 am

flybucky wrote:
XRAYretired wrote:
Yes, it was mea culpa.
http://www.b737.org.uk/mcas.htm
2.5 degrees in 9.26sec cycle = 0.27deg/sec. is the current design.
0.6 degrees in 9.26 sec cycle = 0.065deg/sec was the original design from reports.

I'm not sure if "0.6 degrees in 9.26 sec cycle = 0.065deg/sec was the original design" is true. I know that 0.6º per cycle was the original MCAS design, but are you assuming it was still over a 9.26s period? Or was it at the same 0.27º/s rate (which would be over a period of 2.22 seconds)?


I suppose that's possible, but my understanding is the change was required to increase the rate of change and that keeps it the same. I've not seen anything that suggests the cycle period was changed.


Ray
 
mjoelnir
Posts: 9386
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 10:14 am

Is the rate of change on the electrical trim, be it by automatic or switches on the yoke, adjustable? Is it more than on off and direction? Is there are variable speed electronic?

If no to everything above, than the rate of change would not be adjustable, only the length of puls could influence the amount of degrees.
 
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seahawk
Posts: 9645
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Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 10:33 am

mjoelnir wrote:
seahawk wrote:
mjoelnir wrote:

The news was about no mandatory simulator time on a 737MAX simulator. Still an I-pad only difference training.

I assume one of the reasons could be, that no USA airline had invested into 737MAX simulators. They have very few simulators on order and are still waiting for them. Mandatory simulator training included in the difference training, would mean that no USA airline would have pilots ready in the near future.
So if the 737MAX should get her recertification soon, there would be no certified pilots to fly them.


So you already know that simulator training would be needed even after the fix was installed?


Yes, if you do not want unnecessary risks. The emphasis on no simulator training and sabotaging that useful simulators, that could show MCAS failure conditions, could be bought, is part of the reason that 350 people got killed.


So you already know the future failure conditions of MCAS?
 
mjoelnir
Posts: 9386
Joined: Sun Feb 03, 2013 11:06 pm

Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 10:44 am

seahawk wrote:
mjoelnir wrote:
seahawk wrote:

So you already know that simulator training would be needed even after the fix was installed?


Yes, if you do not want unnecessary risks. The emphasis on no simulator training and sabotaging that useful simulators, that could show MCAS failure conditions, could be bought, is part of the reason that 350 people got killed.


So you already know the future failure conditions of MCAS?


No, but It seems that it is again no interest at FAA or Boeing to train for them. They seem still fighting for being able to state: less cost of training between NG and MAX, than between ceo and neo.

If you do not get it, you do not get it.
 
ArgentoSystems
Posts: 315
Joined: Sun Mar 24, 2019 12:05 am

Re: B737MAX Grounded Worldwide

Wed Apr 17, 2019 10:48 am

sassiciai wrote:
I recently retired after a 40 year career in the "software industry".


All the right questions. The screwup on this relatively simple system is so monumental, I view the whole plane as tainted. I mean, we only know about these problems because of the crashes. But how can we assume the rest of the plane and it's s/w systems was properly engineered in light of this?

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