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RickNRoll
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Re: B737MAX Grounded Worldwide

Sun Mar 24, 2019 11:32 pm

dakota123 wrote:
Amiga500 wrote:
dakota123 wrote:
Not true. Stick force gradient decreases. It doesn’t go negative.


Dunno if that is directed at me - but reduced (or not enough) control authority does not result in an inversion of stick force.

It is not the elevator stalling that is the problem.


Merely a clarification.

Have a look here, OldAeroGuy explains it well in post 28. viewtopic.php?f=5&t=1418159

(Not directed at you; just generally given all the hysteria that “MCAS is a kludge”. )
It is a kludge. The design is poor, the implementation poor, the testing poor and the documentation poor. The explanation of what it is supposed to do is quite clear.
 
ArgentoSystems
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Re: B737MAX Grounded Worldwide

Sun Mar 24, 2019 11:42 pm

In my opinion the only proper fix to the plane is going back to drawing board. Any fixes involving disabling MCAS are complete BS. I would not allow it in any less critical application, let alone airplane. If we can disable MCAS and continue flying normally, when why do we need it to begin with?

It especially worrisome that it can lose it during take off, when airplane is deliberately at higher than normal AoA, and the protection is vital. At the same time the invalid input during take off is extremely dangerous.

Now, regarding the redundancy. 3x redundancy with 2 out of 3 voting is nice when you have extremely reliable input to begin with, say on the order 1 incident in a million of flights. In this case 2 out of 3 makes the MTBF so high that realistically we should never see 2 sensors fail.

But we are dealing with 2 fatal incidents in 18 month x 350 planes. And god knows how many similar incidents that did not end in tragedy. That's a crappy track records. 2 out of 3 can't make this acceptably reliable.
 
chance6
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Re: B737MAX Grounded Worldwide

Sun Mar 24, 2019 11:56 pm

jplatts wrote:
chance6 wrote:
Not only does Boeing suffer but GE/CFM will suffer from it- grounded aircraft means less servicing which is where engine profits are really made. Airlines cancelling orders will mean profit impacts at the engine makers. So get ready, P&W, you're about to get even busier.


There are actually Airbus A319, A320, A320neo, A321, and A321neo planes equipped with CFM engines, and AA, DL, AS, G4, and F9 in the U.S. all operate Airbus A320 family aircraft with CFM engines. AS, DL, and F9 also still have orders for Airbus aircraft equipped with CFM engines that haven't been delivered yet.

While I agree that GE/CFM will suffer from lost sales with the 737 MAX grounding, there will still be demand for GE/CFM engines for Airbus aircraft and non-737 Boeing models as GE/CFM will still be producing engines for Airbus aircraft and non-737 Boeing models.

Do engine design problems exist on GE/CFM engines for Airbus planes or non-737 Boeing planes?


Yeah that's true, there are many aircraft models supported by the GE/CFM, but the 737 MAX (call it MAX AOA now??) is a major operator of the Leap design. I think the Leap is also an option for Airbus A321 (?)...in any case, the MAX AOA aircraft uses Leap, and Leap only. So it will hurt if this next Fix doesn't do the job. It will be 'terminal', so to speak.

As for engine design problems on other aircraft...ha ha no comment.
 
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SheikhDjibouti
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 12:20 am

Chemist wrote:
They didn't "design an unstable aircraft". They modified pyons and added larger engines. Their modeling didn't suggest any adverse effects. Once in flight test, some unexpected pitch behavior was noted ony at high AOAs.
I think Wlederling was particularly taken by your idea that Boeing engineers had not expected a change in pitch behavior. Perhaps they are only qualified to design horse drawn buggies?

Strangely, I seem to have more faith in their design team.
SheikhDjibouti wrote:
I believe their modelling did suggest adverse effects; basically once they had moved the engine forward it was a no-brainer.
Consequently Boeing introduced MCAS with a 0.6deg limit of action.
Then, once in flight test, this was found to be insufficient and they increased it to 2.5deg. (equivalent to maximum deflection in two iterations)

What do you have to support your version?

Chemist wrote:
Well I guess neither of us have those links.
Quelle surprise!

Except... tough luck for you; I found my original link because I actually had one all along and wasn't just inventing facts to suit an agenda.
This Seattle Times article not only supports everything I said above, it also undermines everything you claimed.
https://www.seattletimes.com/business/b ... 0Usl53CXMA

Chemist wrote:
The point being that all the .....accusations don't seem to be founded by any real evidence that I've seen. Lots of accusations without any substance.
You got that bit dead right. :lol:
Unless you can now magic up an article to support your points...... and we all know that isn't going to happen. :scratchchin:
Nothing to see here; move along please.
 
juliuswong
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 1:03 am

Smartwings inducted an Swift Air B737-86J to cover for MAX grounding.

Boeing 737-86J 32917 1210 N917XA Swift Air posn 20mar19 GSO-KEF-PRG on wet-lease to smartwings ex VP-BEN
https://www.skyliner-aviation.de/regdb. ... av4&page=3
- Life is a journey, travel it well -
 
freakyrat
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 1:22 am

jplatts wrote:
Why hasn't WN had any crashes involving the 737 MAX 8 during the 17 months that it operated the MAX 8 planes?

WN 1380 was the only incident at WN during the October 2017 through March 2019 time period that resulted in a fatality, but the WN 1380 incident occurred on a 737-700 plane that was almost 18 years old.

Any safety issues involving both WN's 737 MAX planes and the oldest 737-700's in WN's fleet must be addressed.


WN has the most experience with the MAX conducting 81,000 flying hours of safe operation with the MAX. WN also has AOA sensor redundancy for the MCAS system and also the AOA disagree warning light. They also had the AOA sensor instrumentation added to the PFD.
 
mwmav8r01
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 1:53 am

dakota123 wrote:
WIederling wrote:
dakota123 wrote:
Larger fan blades, gearboxes, hotter cores, 60:1 pressure ratios, LP cores spinning at twice the rpm of previous designs — THOSE are some of the things that we think we understand but maybe don’t fully just yet.


More or less a distraction what you write.
This is about integrating a completely safe engine on an up to now rather save airframe resulting
in a product that has an unpleasant tendency to crash.
superficially about 20..40 times more often than for the predecessors.
Acceptable:
MCAS related crashes would have to have a very small impact on the regular crashrate.


This whole discussion is a distraction. MAX with properly designed MCAS will be as safe as NG. At least, any discussion otherwise is just speculation put out as unassailable fact by a few. And frankly, how do we know the engines are completely safe? Took quite a while for the CF6-80 dovetail slot issue to show.


Logic has no place on airliners.net. I agree. Training (lack thereof), bad software and bad circumstances are what we saw. This is fixable. Fairly easily.
 
AvFanNJ
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 2:37 am

hilram wrote:
STILL
    EASA will do their own independent certification not of MCAS but of THE WHOLE AIRLINER. :airplane:

    The MAX will not fly in Europe (or Asia??) until EASA has certified MAX from bottom up.


The article you linked to says nothing of this sort. We have entirely too much extrapolation in these threads not fully grounded in facts. They have become more like Op-Eds with a lot of folks blowing smoke out of their butts. EASA knows much of this airplane already; it will scrutinize what is new about it vs. the NG but that will not extend to the basic design which differs little from the NG that preceded it. It will properly look at the changes to the engines and aerodynamic tweaks and most importantly, to the new FBW spoilers and most prominently, the suspect MCAS enhancement and its accompanying AOA sensor connections. I'm not minimizing the boatload of dung Boeing is in at this point but we really need to stick to posted truths and not embellish posts with our own interpretations.
 
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hilram
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 7:08 am

AvFanNJ wrote:
hilram wrote:
STILL
    EASA will do their own independent certification not of MCAS but of THE WHOLE AIRLINER. :airplane:

    The MAX will not fly in Europe (or Asia??) until EASA has certified MAX from bottom up.


The article you linked to says nothing of this sort. We have entirely too much extrapolation in these threads not fully grounded in facts. They have become more like Op-Eds with a lot of folks blowing smoke out of their butts. EASA knows much of this airplane already; it will scrutinize what is new about it vs. the NG but that will not extend to the basic design which differs little from the NG that preceded it. It will properly look at the changes to the engines and aerodynamic tweaks and most importantly, to the new FBW spoilers and most prominently, the suspect MCAS enhancement and its accompanying AOA sensor connections. I'm not minimizing the boatload of dung Boeing is in at this point but we really need to stick to posted truths and not embellish posts with our own interpretations.

True, so why do you extrapolate from what I wrote that I claim the EASA knows nothing about the MAX already, and would start to consider whether the NG is safe or not... They will look into every change for MAX and conduct their own assessment since they no longer trust the certification process between Boeing and the FAA. And this was prior to the FBI joining in on the investigation of possible collusion... How many months that independent assessment will take I do not know. I only know Boeing leadership dreams of software quick fixes and rapid restoration of service isn’t going to fly.
Flown on: A319, 320, 321, 332, 333, 343 | B732, 734, 735, 736, 73G, 738, 743, 744, 772, 77W | CRJ9 | BAe-146 | DHC-6, 7, 8 | F50 | E195 | MD DC-9 41, MD-82, MD-87
 
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hongkongflyer
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 7:12 am

https://www.vox.com/the-goods/2019/3/22/18277694/boeing-737-max-ethiopian-airlines-lion-air-safety?fbclid=IwAR3_uIM_teE6trzcGJBL0CbWP7di2CO5TOQ8ELniJpugCLyjJawh1xtwUt0

Hard to believe that the important features of AOA are treated as an optional upgrade.
What a shame to put the profits ahead of safety.
 
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seahawk
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 7:52 am

ArgentoSystems wrote:
In my opinion the only proper fix to the plane is going back to drawing board. Any fixes involving disabling MCAS are complete BS. I would not allow it in any less critical application, let alone airplane. If we can disable MCAS and continue flying normally, when why do we need it to begin with? .


You can safely fly the MAX without MCAS, what you can not do is have exactly the same pilot training for the NG and the MAX. If you disable the MCAS pilots would need extra training for the MAX which would make crew management a little bit more difficult.
 
WIederling
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 7:54 am

osiris30 wrote:
[edit] airspeed isn't needed.. the AoA vanes don't need airspeed.


Min speed to judge AoA input as valid.
Murphy is an optimist
 
WIederling
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 8:00 am

AvFanNJ wrote:
The article you linked to says nothing of this sort. We have entirely too much extrapolation in these threads not fully grounded in facts. They have become more like Op-Eds with a lot of folks blowing smoke out of their butts.


rubs off after longer contact.
What you note has been the bane of US "news" reporting for a couple of decades.
facts and opinion have been mixed for a long time but now it is "facts" ? what "facts" ?
( noteworthy exception in this domain here: Dominic Gates )
Murphy is an optimist
 
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scbriml
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 8:07 am

freakyrat wrote:
WN also has AOA sensor redundancy for the MCAS system


I don't believe there is such a thing. :shakehead:

The pre-grounding MCAS implementation only reads data from one AOA sensor.
Time flies like an arrow. Fruit flies like a banana!
There are 10 types of people in the World - those that understand binary and those that don't.
 
Interested
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 8:07 am

seahawk wrote:
ArgentoSystems wrote:
In my opinion the only proper fix to the plane is going back to drawing board. Any fixes involving disabling MCAS are complete BS. I would not allow it in any less critical application, let alone airplane. If we can disable MCAS and continue flying normally, when why do we need it to begin with? .


You can safely fly the MAX without MCAS, what you can not do is have exactly the same pilot training for the NG and the MAX. If you disable the MCAS pilots would need extra training for the MAX which would make crew management a little bit more difficult.


I feel you are playing with words here

You do accept that the Max plane without MCAS is more likely to stall than a NG plane? That's why MCAS was introduced in the first place.

So although you state it can still be flown safely it's harder and more risky to fly the Max than flying the NG?

And why would we introduce more risk for a new aircraft?

We want to introduce less risk don't we?

Your answer brings the chance of more human error into flying these planes not less. So more crashes over time would be inevitable. We can't remove human error from planes. We can only reduce where it can happen
 
Boof02671
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 8:20 am

ArgentoSystems wrote:
In my opinion the only proper fix to the plane is going back to drawing board. Any fixes involving disabling MCAS are complete BS. I would not allow it in any less critical application, let alone airplane. If we can disable MCAS and continue flying normally, when why do we need it to begin with?

It especially worrisome that it can lose it during take off, when airplane is deliberately at higher than normal AoA, and the protection is vital. At the same time the invalid input during take off is extremely dangerous.

Now, regarding the redundancy. 3x redundancy with 2 out of 3 voting is nice when you have extremely reliable input to begin with, say on the order 1 incident in a million of flights. In this case 2 out of 3 makes the MTBF so high that realistically we should never see 2 sensors fail.

But we are dealing with 2 fatal incidents in 18 month x 350 planes. And god knows how many similar incidents that did not end in tragedy. That's a crappy track records. 2 out of 3 can't make this acceptably reliable.

And where did you get you’re aviation engineering degree?
 
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Jouhou
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 8:23 am

Boof02671 wrote:
ArgentoSystems wrote:
In my opinion the only proper fix to the plane is going back to drawing board. Any fixes involving disabling MCAS are complete BS. I would not allow it in any less critical application, let alone airplane. If we can disable MCAS and continue flying normally, when why do we need it to begin with?

It especially worrisome that it can lose it during take off, when airplane is deliberately at higher than normal AoA, and the protection is vital. At the same time the invalid input during take off is extremely dangerous.

Now, regarding the redundancy. 3x redundancy with 2 out of 3 voting is nice when you have extremely reliable input to begin with, say on the order 1 incident in a million of flights. In this case 2 out of 3 makes the MTBF so high that realistically we should never see 2 sensors fail.

But we are dealing with 2 fatal incidents in 18 month x 350 planes. And god knows how many similar incidents that did not end in tragedy. That's a crappy track records. 2 out of 3 can't make this acceptably reliable.

And where did you get you’re aviation engineering degree?


Demanding redundancy is exactly something a *good* engineer would do.
情報
 
Boof02671
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 8:30 am

Jouhou wrote:
Boof02671 wrote:
ArgentoSystems wrote:
In my opinion the only proper fix to the plane is going back to drawing board. Any fixes involving disabling MCAS are complete BS. I would not allow it in any less critical application, let alone airplane. If we can disable MCAS and continue flying normally, when why do we need it to begin with?

It especially worrisome that it can lose it during take off, when airplane is deliberately at higher than normal AoA, and the protection is vital. At the same time the invalid input during take off is extremely dangerous.

Now, regarding the redundancy. 3x redundancy with 2 out of 3 voting is nice when you have extremely reliable input to begin with, say on the order 1 incident in a million of flights. In this case 2 out of 3 makes the MTBF so high that realistically we should never see 2 sensors fail.

But we are dealing with 2 fatal incidents in 18 month x 350 planes. And god knows how many similar incidents that did not end in tragedy. That's a crappy track records. 2 out of 3 can't make this acceptably reliable.

And where did you get you’re aviation engineering degree?


Demanding redundancy is exactly something a *good* engineer would do.



That’s not what I asked. If you aren’t an Aviation Engineer nor part of the design, evaluation, safety nor an investigator who is privy to all the information then it’s just armchair speculation.
Last edited by Boof02671 on Mon Mar 25, 2019 8:31 am, edited 2 times in total.
 
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seahawk
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 8:30 am

Interested wrote:
seahawk wrote:
ArgentoSystems wrote:
In my opinion the only proper fix to the plane is going back to drawing board. Any fixes involving disabling MCAS are complete BS. I would not allow it in any less critical application, let alone airplane. If we can disable MCAS and continue flying normally, when why do we need it to begin with? .


You can safely fly the MAX without MCAS, what you can not do is have exactly the same pilot training for the NG and the MAX. If you disable the MCAS pilots would need extra training for the MAX which would make crew management a little bit more difficult.


I feel you are playing with words here

You do accept that the Max plane without MCAS is more likely to stall than a NG plane? That's why MCAS was introduced in the first place.


Maybe you want to watch that video: https://www.youtube.com/watch?v=TlinocVHpzk

The MAX is not more likely to stall, it handles differently in a stall though, as it has less elevator authority in a high thrust stall and needs stabilizer support when the NG does not.
 
Interested
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 8:31 am

ArgentoSystems wrote:
In my opinion the only proper fix to the plane is going back to drawing board. Any fixes involving disabling MCAS are complete BS. I would not allow it in any less critical application, let alone airplane. If we can disable MCAS and continue flying normally, when why do we need it to begin with?

It especially worrisome that it can lose it during take off, when airplane is deliberately at higher than normal AoA, and the protection is vital. At the same time the invalid input during take off is extremely dangerous.

Now, regarding the redundancy. 3x redundancy with 2 out of 3 voting is nice when you have extremely reliable input to begin with, say on the order 1 incident in a million of flights. In this case 2 out of 3 makes the MTBF so high that realistically we should never see 2 sensors fail.

But we are dealing with 2 fatal incidents in 18 month x 350 planes. And god knows how many similar incidents that did not end in tragedy. That's a crappy track records. 2 out of 3 can't make this acceptably reliable.


The stats are actually far worse than you describe

There were only 350 planes flying at the end of 18 months

At the start there would be far far less.

The more planes introduced the more potential for systems error and human error combined
 
Boof02671
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 8:33 am

Interested wrote:
ArgentoSystems wrote:
In my opinion the only proper fix to the plane is going back to drawing board. Any fixes involving disabling MCAS are complete BS. I would not allow it in any less critical application, let alone airplane. If we can disable MCAS and continue flying normally, when why do we need it to begin with?

It especially worrisome that it can lose it during take off, when airplane is deliberately at higher than normal AoA, and the protection is vital. At the same time the invalid input during take off is extremely dangerous.

Now, regarding the redundancy. 3x redundancy with 2 out of 3 voting is nice when you have extremely reliable input to begin with, say on the order 1 incident in a million of flights. In this case 2 out of 3 makes the MTBF so high that realistically we should never see 2 sensors fail.

But we are dealing with 2 fatal incidents in 18 month x 350 planes. And god knows how many similar incidents that did not end in tragedy. That's a crappy track records. 2 out of 3 can't make this acceptably reliable.


The stats are actually far worse than you describe

There were only 350 planes flying at the end of 18 months

At the start there would be far far less.

The more planes introduced the more potential for systems error and human error combined

And yet two of the largest airline WN with 34 and AA with 24 and over 100,000 hours had zero incidents.
 
Interested
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 8:38 am

seahawk wrote:
Interested wrote:
seahawk wrote:

You can safely fly the MAX without MCAS, what you can not do is have exactly the same pilot training for the NG and the MAX. If you disable the MCAS pilots would need extra training for the MAX which would make crew management a little bit more difficult.


I feel you are playing with words here

You do accept that the Max plane without MCAS is more likely to stall than a NG plane? That's why MCAS was introduced in the first place.


Maybe you want to watch that video: https://www.youtube.com/watch?v=TlinocVHpzk

The MAX is not more likely to stall, it handles differently in a stall though, as it has less elevator authority in a high thrust stall and needs stabilizer support when the NG does not.


Can we just simplify this by both accepting that the Max is harder and more difficult for pilots to control in a potential stall situation without MCAS?

More training and more risk involved.

however small the extra risk it means these planes are less safe to fly.
 
Interested
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 8:40 am

Boof02671 wrote:
Interested wrote:
ArgentoSystems wrote:
In my opinion the only proper fix to the plane is going back to drawing board. Any fixes involving disabling MCAS are complete BS. I would not allow it in any less critical application, let alone airplane. If we can disable MCAS and continue flying normally, when why do we need it to begin with?

It especially worrisome that it can lose it during take off, when airplane is deliberately at higher than normal AoA, and the protection is vital. At the same time the invalid input during take off is extremely dangerous.

Now, regarding the redundancy. 3x redundancy with 2 out of 3 voting is nice when you have extremely reliable input to begin with, say on the order 1 incident in a million of flights. In this case 2 out of 3 makes the MTBF so high that realistically we should never see 2 sensors fail.

But we are dealing with 2 fatal incidents in 18 month x 350 planes. And god knows how many similar incidents that did not end in tragedy. That's a crappy track records. 2 out of 3 can't make this acceptably reliable.


The stats are actually far worse than you describe

There were only 350 planes flying at the end of 18 months

At the start there would be far far less.

The more planes introduced the more potential for systems error and human error combined

And yet two of the largest airline WN with 34 and AA with 24 and over 100,000 hours had zero incidents.


100,000 hrs without incident is worth nothing in aviation or safety terms

How many actual flights is that?

30,000?

It's barely one day of flights with 5,000 of these planes in operation as is planned?

You are quoting stats that make you seem naive? I'm sure you aren't naive?
 
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scbriml
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 8:44 am

Boof02671 wrote:
And yet two of the largest airline WN with 34 and AA with 24 and over 100,000 hours had zero incidents.


It would be correct to say they've had zero crashes. Zero "incidents" we can be less sure about. It's entirely possible that AA and WN had been lucky and not had any sensor failures (which both Lion and Ethiopian seem to have had).

Accidents rarely happen linearly, so there's that as well.
Time flies like an arrow. Fruit flies like a banana!
There are 10 types of people in the World - those that understand binary and those that don't.
 
Interested
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 8:51 am

The NG has over 100,000 hours of flights every day by my estimates

There you have stats worth discussing

In comparison the Max was upto about 5,000 worldwide hrs a day before grounding I estimate with 2 disasters in 5 months

Those two US airlines less than 800 hrs per day I estimate in max planes?

How many NGs crashed with all crew and passengers perished in last 5 months?
Last edited by Interested on Mon Mar 25, 2019 9:04 am, edited 4 times in total.
 
Amiga500
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 8:57 am

dakota123 wrote:
Amiga500 wrote:
dakota123 wrote:
Bullsh*t. No more a kludge than Mach trim or rudder limiters.


I suggest you go try and understand the FARs (in this case, specifically 25.103 and 25.203 - and might as well look at 25.672 while you are at it) to see why one is a kludge and the others are accepted means of improving control and/or safety.


Many, many times, thank you very much. How do you think they got to be accepted in the first place? In many cases, only after an issue presented itself for the first time.


You've done what many many times? Certainly not read the FARs - if you had - we wouldn't be having this discussion.


What do you mean by "they got to be accepted in the first place"? The basis for how the FARs were constructed? If that is what you mean - yes, indeed it was only after an incident the regulations were modified as per the lessons learned from that incident.

Problem for the MAX is - MCAS is operating contrary to regulations which were constructed - as you yourself say - from lessons learned from past incidents.
 
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seahawk
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 9:05 am

Interested wrote:
seahawk wrote:
Interested wrote:

I feel you are playing with words here

You do accept that the Max plane without MCAS is more likely to stall than a NG plane? That's why MCAS was introduced in the first place.


Maybe you want to watch that video: https://www.youtube.com/watch?v=TlinocVHpzk

The MAX is not more likely to stall, it handles differently in a stall though, as it has less elevator authority in a high thrust stall and needs stabilizer support when the NG does not.


Can we just simplify this by both accepting that the Max is harder and more difficult for pilots to control in a potential stall situation without MCAS?

More training and more risk involved.

however small the extra risk it means these planes are less safe to fly.


Imho it is not. The MAX shows no nasty stall characteristic, the elevator control authority is just different to the NG, which also can need stabilizer support to get the nose down in a high thrust stall - infact this is standard OP for the NG stall training. Elevator down, trim nose down, keep engine thrust low, wait till nose comes down and AoA reduces, then slowly increase thrust. Once AoA and speed are no longer amber trim back and return to level flight.
 
Interested
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 9:24 am

seahawk wrote:
Interested wrote:
seahawk wrote:

Maybe you want to watch that video: https://www.youtube.com/watch?v=TlinocVHpzk

The MAX is not more likely to stall, it handles differently in a stall though, as it has less elevator authority in a high thrust stall and needs stabilizer support when the NG does not.


Can we just simplify this by both accepting that the Max is harder and more difficult for pilots to control in a potential stall situation without MCAS?

More training and more risk involved.

however small the extra risk it means these planes are less safe to fly.


Imho it is not. The MAX shows no nasty stall characteristic, the elevator control authority is just different to the NG, which also can need stabilizer support to get the nose down in a high thrust stall - infact this is standard OP for the NG stall training. Elevator down, trim nose down, keep engine thrust low, wait till nose comes down and AoA reduces, then slowly increase thrust. Once AoA and speed are no longer amber trim back and return to level flight.


So if I hypothetically accept what you say is correct and that we both accept the MCAS system itself is an extra risk that can lead to failures and extra risk - then what you are saying suggests one solution here is no longer use MCAS for these planes to get them certified as safe

Boeing accept they have to now train people for the above but at least we remove the risk of MCAS system failures full stop

It becomes an option once Boeing accepts new pilot training is needed?

If so to me thats the best option for safety PROVIDING what you say is correct above and this isn't a less safe way of flying

Don't introduce new systems that can fail if they aren't needed for safety.
 
Amiga500
Posts: 2645
Joined: Tue Mar 03, 2015 8:22 am

Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 10:38 am

seahawk wrote:
Imho it is not. The MAX shows no nasty stall characteristic, the elevator control authority is just different to the NG, which also can need stabilizer support to get the nose down in a high thrust stall - infact this is standard OP for the NG stall training.


You contradict yourself within a single sentence.


Even I have to put in a good bit of effort to do that!! :D
 
art
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 10:59 am

My understanding is limited but I have to ask this: why use the trim system to avoid entering / getting too close to a stall? Why not just use the standard warnings (which I imagine include activating a stick shaker)?

Subsidiary question here, please: with FBW aircraft using a small side-mounted control, what is their equivalent of a stick shaker warning as a stall is approached?
 
Boof02671
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:01 am

scbriml wrote:
Boof02671 wrote:
And yet two of the largest airline WN with 34 and AA with 24 and over 100,000 hours had zero incidents.


It would be correct to say they've had zero crashes. Zero "incidents" we can be less sure about. It's entirely possible that AA and WN had been lucky and not had any sensor failures (which both Lion and Ethiopian seem to have had).

Accidents rarely happen linearly, so there's that as well.

AA has the extra warning system installed, WN didn’t but they are getting it installed on the planes already in service and added it to their new builds.
 
Boof02671
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:02 am

Interested wrote:
Boof02671 wrote:
Interested wrote:

The stats are actually far worse than you describe

There were only 350 planes flying at the end of 18 months

At the start there would be far far less.

The more planes introduced the more potential for systems error and human error combined

And yet two of the largest airline WN with 34 and AA with 24 and over 100,000 hours had zero incidents.


100,000 hrs without incident is worth nothing in aviation or safety terms

How many actual flights is that?

30,000?

It's barely one day of flights with 5,000 of these planes in operation as is planned?

You are quoting stats that make you seem naive? I'm sure you aren't naive?

You are missing the point, two of the largest operators had no problems as well as UA.
 
VSMUT
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:03 am

art wrote:
My understanding is limited but I have to ask this: why use the trim system to avoid entering / getting too close to a stall? Why not just use the standard warnings (which I imagine include activating a stick shaker)?


Just a guess, but if the MAX already gets into these AoA ssues at angles of attack at angles normally experienced during a take-off, then the stick shaker would run during a standard departure.

And again, it would mean different training between the NG and the MAX.
 
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seahawk
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:10 am

Amiga500 wrote:
seahawk wrote:
Imho it is not. The MAX shows no nasty stall characteristic, the elevator control authority is just different to the NG, which also can need stabilizer support to get the nose down in a high thrust stall - infact this is standard OP for the NG stall training.


You contradict yourself within a single sentence.

Even I have to put in a good bit of effort to do that!! :D


Not a contradiction, as I understand the flyboys you would try to minimize the altitude lost by getting the nose down as quickly as possible, so on the NG you use the stab trim even though the elevator would be enough to bring the nose down. But I have not heard a pilot call this a nasty stall behaviour.
 
StTim
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:12 am

Just because AA and WN had zero incidents doesn't mean that they are miraculously better than those that did. It may mean they were just lucky!
 
Boof02671
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:12 am

StTim wrote:
Just because AA and WN had zero incidents doesn't mean that they are miraculously better than those that did. It may mean they were just lucky!

You can’t make that claim. Total speculation with no data to back it up.
 
Condorman
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:21 am

Could the MCAS system be removed and pilots simply trained up to deal with the handling characteristics of the plane?

Without MCAS would the 737 still be able to be certified by Aviation Authorities?

Is MCAS the proverbial lipstick on a pig?
 
Amiga500
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:25 am

seahawk wrote:
Amiga500 wrote:
seahawk wrote:
Imho it is not. The MAX shows no nasty stall characteristic, the elevator control authority is just different to the NG, which also can need stabilizer support to get the nose down in a high thrust stall - infact this is standard OP for the NG stall training.


You contradict yourself within a single sentence.

Even I have to put in a good bit of effort to do that!! :D


Not a contradiction, as I understand the flyboys you would try to minimize the altitude lost by getting the nose down as quickly as possible, so on the NG you use the stab trim even though the elevator would be enough to bring the nose down. But I have not heard a pilot call this a nasty stall behaviour.


Having to rely on your trim functionality to get out of a stall situation is nasty stall behaviour!

Take too long to realise you need more than elevators to drop the nose and you could end up in a scenario where your forward airspeed is that low (and elevators stalled out so) you've no control authority.
 
Amiga500
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:27 am

Condorman wrote:
Without MCAS would the 737 still be able to be certified by Aviation Authorities?
Is MCAS the proverbial lipstick on a pig?


I'm wondering can it be certified with or without it (given the high level MCAS concept).
 
art
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:28 am

VSMUT wrote:
art wrote:
My understanding is limited but I have to ask this: why use the trim system to avoid entering / getting too close to a stall? Why not just use the standard warnings (which I imagine include activating a stick shaker)?


Just a guess, but if the MAX already gets into these AoA ssues at angles of attack at angles normally experienced during a take-off, then the stick shaker would run during a standard departure.

And again, it would mean different training between the NG and the MAX.


Thanks for the response. It seems a lot of things were geared to avoiding any 'hands on' NG to MAX conversion training.

Any reason why a MAX should not use a shallower climb out of an airport (to lower AoA) than an NG? I don't see that there would be much retraining involved in that.
 
yabeweb
Posts: 88
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:29 am

Boeing is releasing a fix, but a fix to what? I mean if the investigation still have not pointed to the real issue, either Boeing knew all along the system was faulty and was working on the background to solve the issue hoping nothing would happend in between updates, of this is a Fix for something that MIGHT not be the issue.

I am all for Boeing fixing stuff, but how are we to know that the fix they are making is the one that caused the issue if investigation are still ongoing?

It does not make sense to me, Boeing:"here we have a fix", Investigators "A fix to what? we still haven't found the cause...."
 
VSMUT
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:34 am

art wrote:
VSMUT wrote:
art wrote:
My understanding is limited but I have to ask this: why use the trim system to avoid entering / getting too close to a stall? Why not just use the standard warnings (which I imagine include activating a stick shaker)?


Just a guess, but if the MAX already gets into these AoA ssues at angles of attack at angles normally experienced during a take-off, then the stick shaker would run during a standard departure.

And again, it would mean different training between the NG and the MAX.


Thanks for the response. It seems a lot of things were geared to avoiding any 'hands on' NG to MAX conversion training.

Any reason why a MAX should not use a shallower climb out of an airport (to lower AoA) than an NG? I don't see that there would be much retraining involved in that.


Because airports often require minimum climb rates, due to either noise abatement or terrain, and shallow climb rates would severely limit it.
And again, that would require more training...
Last edited by VSMUT on Mon Mar 25, 2019 11:34 am, edited 1 time in total.
 
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scbriml
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:34 am

StTim wrote:
Just because AA and WN had zero incidents doesn't mean that they are miraculously better than those that did. It may mean they were just lucky!


:checkmark:

Boof02671 wrote:
You can’t make that claim. Total speculation with no data to back it up.


Accidents don't happen in a linear fashion and the comparatively low number of in-service frames and total hours doesn't tell the story you seem to think it does.

Has AA or WN suffered AOA and/or IAS failures on take off as Lion and Ethiopian appeared to have? Do you have the data for that?
How often has AA or WN had to use the trim cutoff switches on the MAX? Do you have data for that?
Time flies like an arrow. Fruit flies like a banana!
There are 10 types of people in the World - those that understand binary and those that don't.
 
mjoelnir
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:38 am

Boof02671 wrote:
StTim wrote:
Just because AA and WN had zero incidents doesn't mean that they are miraculously better than those that did. It may mean they were just lucky!

You can’t make that claim. Total speculation with no data to back it up.


Of course he can make that claim. And there is data to back it up. To few flights at AA and WN to make significant that they had no accidents. How often did a AA or WN flight had an AoA sensor or downstream electronic failure and did land safely? Let us guess at none?
Less than 20 % of the delivered 737MAX are used by airlines based in the USA, so the likelihood for an accident there has been lower than an accident outside the USA.
 
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seahawk
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:45 am

Amiga500 wrote:
seahawk wrote:
Amiga500 wrote:

You contradict yourself within a single sentence.

Even I have to put in a good bit of effort to do that!! :D


Not a contradiction, as I understand the flyboys you would try to minimize the altitude lost by getting the nose down as quickly as possible, so on the NG you use the stab trim even though the elevator would be enough to bring the nose down. But I have not heard a pilot call this a nasty stall behaviour.


Having to rely on your trim functionality to get out of a stall situation is nasty stall behaviour!

Take too long to realise you need more than elevators to drop the nose and you could end up in a scenario where your forward airspeed is that low (and elevators stalled out so) you've no control authority.


If that really is the case on the MAX, it would indeed be a big problem for Boeing. I do not know enough about MCAS or the MAX in general to make any comment on it though.
 
Interested
Posts: 887
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:45 am

Boof02671 wrote:
Interested wrote:
Boof02671 wrote:
And yet two of the largest airline WN with 34 and AA with 24 and over 100,000 hours had zero incidents.


100,000 hrs without incident is worth nothing in aviation or safety terms

How many actual flights is that?

30,000?

It's barely one day of flights with 5,000 of these planes in operation as is planned?

You are quoting stats that make you seem naive? I'm sure you aren't naive?

You are missing the point, two of the largest operators had no problems as well as UA.


But they've not flown anywhere enough hours for the sample to be worthwhile or prove anything?
 
Boof02671
Posts: 2127
Joined: Sun Jul 10, 2016 12:15 am

Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:47 am

100,000 hours is not a few flights. WN and AA are two of the largest Max 8 operators, and no he has no data to back up his claim.

Say an average flight is three hours that’s 33,000 flights AA and WN have operated.
 
Interested
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Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 11:50 am

seahawk wrote:
Amiga500 wrote:
seahawk wrote:

Not a contradiction, as I understand the flyboys you would try to minimize the altitude lost by getting the nose down as quickly as possible, so on the NG you use the stab trim even though the elevator would be enough to bring the nose down. But I have not heard a pilot call this a nasty stall behaviour.


Having to rely on your trim functionality to get out of a stall situation is nasty stall behaviour!

Take too long to realise you need more than elevators to drop the nose and you could end up in a scenario where your forward airspeed is that low (and elevators stalled out so) you've no control authority.


If that really is the case on the MAX, it would indeed be a big problem for Boeing. I do not know enough about MCAS or the MAX in general to make any comment on it though.


But earlier in the thread you've twice to told me that the Max is pefectly safe to fly without MCAS?

And no less safe than flying NG without MCAS?
 
VSMUT
Posts: 4567
Joined: Mon Aug 08, 2016 11:40 am

Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 12:13 pm

VSMUT wrote:
art wrote:
VSMUT wrote:

Just a guess, but if the MAX already gets into these AoA ssues at angles of attack at angles normally experienced during a take-off, then the stick shaker would run during a standard departure.

And again, it would mean different training between the NG and the MAX.


Thanks for the response. It seems a lot of things were geared to avoiding any 'hands on' NG to MAX conversion training.

Any reason why a MAX should not use a shallower climb out of an airport (to lower AoA) than an NG? I don't see that there would be much retraining involved in that.


Because airports often require minimum climb rates, due to either noise abatement or terrain, and shallow climb rates would severely limit it.
And again, that would require more training...


And come to think of it, it may also present an issue with single engine performance.
 
marcelh
Posts: 1042
Joined: Wed Jun 19, 2013 12:43 pm

Re: B737MAX Grounded Worldwide

Mon Mar 25, 2019 12:13 pm

StTim wrote:
Just because AA and WN had zero incidents doesn't mean that they are miraculously better than those that did. It may mean they were just lucky!

And there is a reason why they have chosen all the optional bells and whistles...

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