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par13del
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 1:25 pm

kalvado wrote:
So far, certification review is the words I heard - but I wonder if there is anything specific they're looking at.

So they are just going to do certification review in the hope that they will find something to review?
Should be easy, there will always be something that was overlooked or not stated clearly, the issue of whether they are fundamental to anything can be discussed after the fact.
 
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Revelation
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 1:37 pm

AVGeekNY wrote:
My confidence and trust is forever shaken in Boeing. After watching the 60 minutes Australia, reading commentary from pilots and this article https://medium.com/@gregoryreedtravis/t ... b1869839b6 I don't know how the Max could ever be trusted.

A question for 737 pilots, if the need for MCAS was driven by quirky aerodynamics then why should we even trust the aircraft design?

Seems the media has done its job in getting you agitated.

Didn't you take away from all of that viewing that those "quirky aerodynamics" only happened when the airplane was approaching the stall condition?

Didn't you wonder why in both crashes the pilots didn't respond to the stick shaker telling them they were heading towards a stall in a timely fashion?
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AVGeekNY
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 1:42 pm

Revelation wrote:
AVGeekNY wrote:
My confidence and trust is forever shaken in Boeing. After watching the 60 minutes Australia, reading commentary from pilots and this article https://medium.com/@gregoryreedtravis/t ... b1869839b6 I don't know how the Max could ever be trusted.

A question for 737 pilots, if the need for MCAS was driven by quirky aerodynamics then why should we even trust the aircraft design?

Seems the media has done its job in getting you agitated.

Didn't you take away from all of that viewing that those "quirky aerodynamics" only happened when the airplane was approaching the stall condition?

Didn't you wonder why in both crashes the pilots didn't respond to the stick shaker telling them they were heading towards a stall in a timely fashion?


I listened to what the pilots from American Airlines pilots said and what the pilot said in the sim on 60 minutes. I read the articles from engineers, pilots and software developers. I think it's pretty clear that any airplane that pitches up so significantly when power is applied that it needs a computer to avoid a stall because it doesn't fly like other 737s sounds like a serious issue.

Are you a 737 pilot?
 
morrisond
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 1:50 pm

AVGeekNY wrote:
Revelation wrote:
AVGeekNY wrote:
My confidence and trust is forever shaken in Boeing. After watching the 60 minutes Australia, reading commentary from pilots and this article https://medium.com/@gregoryreedtravis/t ... b1869839b6 I don't know how the Max could ever be trusted.

A question for 737 pilots, if the need for MCAS was driven by quirky aerodynamics then why should we even trust the aircraft design?

Seems the media has done its job in getting you agitated.

Didn't you take away from all of that viewing that those "quirky aerodynamics" only happened when the airplane was approaching the stall condition?

Didn't you wonder why in both crashes the pilots didn't respond to the stick shaker telling them they were heading towards a stall in a timely fashion?


I listened to what the pilots from American Airlines pilots said and what the pilot said in the sim on 60 minutes. I read the articles from engineers, pilots and software developers. I think it's pretty clear that any airplane that pitches up so significantly when power is applied that it needs a computer to avoid a stall because it doesn't fly like other 737s sounds like a serious issue.

Are you a 737 pilot?


All underwing planes pitch up when power is applied. That is not the issue. When you are approaching stall - because of the extra nacelle lift the controls get slightly light - not really causing any safety issues but not allowed by the FAR's.

Because of the higher mounting of the MAX engines the Pitch up effect due to power should be less than the NG.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 1:59 pm

AVGeekNY wrote:
I think it's pretty clear that any airplane that pitches up so significantly when power is applied that it needs a computer to avoid a stall because it doesn't fly like other 737s sounds like a serious issue.

The situation that triggers MCAS is not typically triggered by the application of power.

AVGeekNY wrote:
Are you a 737 pilot?

No, but I have a PPL and understand the conditions under which a plane can stall, have performed a dozen or more stalls myself, and this thread and others have informed me about the issues that MCAS tries to address, which is a reduction in yoke pressure as the plane approaches a stall due to the lift generated by the nacelles on the MAX.

Sure, you can get pilots to put the simulator into some pretty challenging situations and then use TV production techniques to generate all kinds of responses, but good airmanship means you don't let things get to the point that MCAS's actions become a challenging situation.
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kalvado
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 2:00 pm

par13del wrote:
kalvado wrote:
So far, certification review is the words I heard - but I wonder if there is anything specific they're looking at.

So they are just going to do certification review in the hope that they will find something to review?
Should be easy, there will always be something that was overlooked or not stated clearly, the issue of whether they are fundamental to anything can be discussed after the fact.

What is the probability that something serious is overlooked? I don't know. Possibly higher than for other designs - there was at least one big problem.
I would say it is wise to look at things closely; and from my perspective such effort should be spearheaded by Boeing at this point. They seem totally relaxed and self-confident though, more concerned about dates than anything else. Which may be a good sign - or quite a troubling sign, as they were in the same mode before ET crash.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 2:04 pm

Revelation wrote:
AVGeekNY wrote:
I think it's pretty clear that any airplane that pitches up so significantly when power is applied that it needs a computer to avoid a stall because it doesn't fly like other 737s sounds like a serious issue.

The situation that triggers MCAS is not typically triggered by the application of power.

One of the things I haven't heard yet - when MCAS is actually expected to act? Not "at high AoA", but situation wise? Turbulence, overly aggressive go-around or collision avoidance, something else? Is there any statistics on that - other than it is "very infrequent"?
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 2:15 pm

At “high AOA” in a clean wing configuration is all that’s needed to define it. Could be an AF 447 event or FlyDubai. It just doesn’t happen randomly, it happens when pilots mishandle the plane without realizing what they’re doing. High AOA is pretty rare in normal operations.

GF
 
AVGeekNY
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 2:20 pm

Revelation wrote:
AVGeekNY wrote:
I think it's pretty clear that any airplane that pitches up so significantly when power is applied that it needs a computer to avoid a stall because it doesn't fly like other 737s sounds like a serious issue.

The situation that triggers MCAS is not typically triggered by the application of power.

AVGeekNY wrote:
Are you a 737 pilot?

No, but I have a PPL and understand the conditions under which a plane can stall, have performed a dozen or more stalls myself, and this thread and others have informed me about the issues that MCAS tries to address, which is a reduction in yoke pressure as the plane approaches a stall due to the lift generated by the nacelles on the MAX.

Sure, you can get pilots to put the simulator into some pretty challenging situations and then use TV production techniques to generate all kinds of responses, but good airmanship means you don't let things get to the point that MCAS's actions become a challenging situation.


Thank you for answering. Our credentials are perhaps somewhat similar. I'm PPL, engineering and software. Did you actually watch the 60 minutes Australia? Also suggest that you read the article I linked by Greg Travis. You may find them informative and interesting.

Obviously what Boeing did was an epic fail. I'm not trusting of what was rolled out. Sounds borderline criminal to me. The AA pilots don't sound like they are in any hurry to trust anything from Boeing. If a plane needs MCAS to be safe then the plane may not be so good, at least not as a 737. My prediction is that this thing continues to get uglier by the day and it's just getting started. I bet we're 6 months if ever before it flys again.
Last edited by AVGeekNY on Wed May 15, 2019 2:48 pm, edited 1 time in total.
 
StTim
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 2:38 pm

The continual publicity that this issue is having means that Boeing are under a microscope in a way I have not seen before.

https://www.bbc.co.uk/news/business-48281282
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 2:58 pm

GalaxyFlyer wrote:
At “high AOA” in a clean wing configuration is all that’s needed to define it. Could be an AF 447 event or FlyDubai. It just doesn’t happen randomly, it happens when pilots mishandle the plane without realizing what they’re doing. High AOA is pretty rare in normal operations.

GF


Add to that an aft cg and loaded wing (steep turn - high angle of bank) and it becomes even more rare.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 3:04 pm

That Boeing is going to pay out $Bs to survivors and airlines is probably history at this point. Boeing's hope needs to be moving forward at this point. I trust that the FAA and international agencies are looking at all of the possible issues of the MAX, demanding emails and interviews with appropriate Boeing engineers and others. While criminal investigations could cloud this, lawyers urging silence, Boeing is not going to deliver frames around the world until the questions are answered and re-certification takes place. At this point every question has to be answered with the truth, the whole truth, and nothing but the truth.

If there are criminal convictions (and I suspect they would be of the misdemeanor and not felony level), Boeing is going to have to acknowledgment some responsibility for them. More usefully, the older system of oversight needs to be reinstated. The safety officer must report to the FAA and not to Boeing management. How did that ever get approved?

Nothing above demands huge delays in the re certification. The MAX is likely a superb plane, just a little different than the NG. To be fair stricter certification on all re-dos is in order. Boeing likely has already stepped up on this for the 777X.
Last edited by frmrCapCadet on Wed May 15, 2019 3:07 pm, edited 1 time in total.
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 3:04 pm

RickNRoll wrote:
AABusDrvr wrote:
vrbarreto wrote:

If by deficiencies you mean 'clairvoyance' especially in terms of the lion Air pilots then many would be in complete agreement with you.


I will reserve judgement until the final reports are out, but it appears he isn't wrong. Why the Lion air crew didn't jump on the "RUNAWAY STABILIZER' NNC is an issue. On the 737, it's the only proper checklist to address any uncommanded and/or inappropriate movement of the stabilizer. If they didn't know that, it's a clear deficiency in their training.

The wildcard with ET in my mind is the normal stab trim system. Boeing states it will stop, and reverse the MCAS trim commands. If it was working as advertised, then the crew wasn't flying the airplane, it was flying them. Thats another training or experience issue.

But again, the full CVR transcripts, and final reports should clear a bunch of this up for everyone.


They were dealing with issues from the moment they took off. With multiple issues to deal with runaway stabiliser was down on the list. Pilot overload.


The issues they were dealing with prior to MCAS activation are ones any crew would be expected to handle -- they didn't.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 3:12 pm

morrisond wrote:
AVGeekNY wrote:
I listened to what the pilots from American Airlines pilots said and what the pilot said in the sim on 60 minutes. I read the articles from engineers, pilots and software developers. I think it's pretty clear that any airplane that pitches up so significantly when power is applied that it needs a computer to avoid a stall because it doesn't fly like other 737s sounds like a serious issue.

Are you a 737 pilot?


All underwing planes pitch up when power is applied. That is not the issue. When you are approaching stall - because of the extra nacelle lift the controls get slightly light - not really causing any safety issues but not allowed by the FAR's.

Because of the higher mounting of the MAX engines the Pitch up effect due to power should be less than the NG.


. . . not really causing any safety issues but not allowed by the FAR's. Contradictio in terminis.

The FAR's are there to guarantee a standard of safety?

Having insufficient pitch stability margin (in some part of the flight envelope) seems to be pretty much safety related.
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 3:20 pm

Revelation wrote:
Sure, you can get pilots to put the simulator into some pretty challenging situations and then use TV production techniques to generate all kinds of responses, but good airmanship means you don't let things get to the point that MCAS's actions become a challenging situation.


There are *a lot of* systems, control logics etc, in any modern airliner that need not be there if all pilots would practice good airmanship 100% of the time.

Luckily, these days we understand and accept that that is (unfortnunately) not always the case, and we need those systems (inlcuding stick shakers/pushers, stall warnings, EGPWS, proper MCAS, and associated FAR's like for control column force vs speed curve) because of just that.

Unfortunately, it was poor MCAS design that let things get to the point that put several crews in a challenging situation.
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morrisond
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 3:23 pm

PW100 wrote:
morrisond wrote:
AVGeekNY wrote:
I listened to what the pilots from American Airlines pilots said and what the pilot said in the sim on 60 minutes. I read the articles from engineers, pilots and software developers. I think it's pretty clear that any airplane that pitches up so significantly when power is applied that it needs a computer to avoid a stall because it doesn't fly like other 737s sounds like a serious issue.

Are you a 737 pilot?


All underwing planes pitch up when power is applied. That is not the issue. When you are approaching stall - because of the extra nacelle lift the controls get slightly light - not really causing any safety issues but not allowed by the FAR's.

Because of the higher mounting of the MAX engines the Pitch up effect due to power should be less than the NG.


. . . not really causing any safety issues but not allowed by the FAR's. Contradictio in terminis.

The FAR's are there to guarantee a standard of safety?

Having insufficient pitch stability margin (in some part of the flight envelope) seems to be pretty much safety related.


So how many MAX's do you think would actually get into a stall and crash if they didn't have MCAS? They would have to pull through this slightly light area of control force, ignore the stick shaker, the warning alarms and the frame buffeting for probably 10-20 seconds before entering an actual stall and then not be able to recover it - which should be achievable by any commercial pilot.

Basically if a pilot actually crashed a MAX after doing all the above and not performing the recovery no one in Aviation would consider them competent enough to fly a Cessna. It would be gross incompetence.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 3:26 pm

7BOEING7 wrote:
RickNRoll wrote:
AABusDrvr wrote:

I will reserve judgement until the final reports are out, but it appears he isn't wrong. Why the Lion air crew didn't jump on the "RUNAWAY STABILIZER' NNC is an issue. On the 737, it's the only proper checklist to address any uncommanded and/or inappropriate movement of the stabilizer. If they didn't know that, it's a clear deficiency in their training.

The wildcard with ET in my mind is the normal stab trim system. Boeing states it will stop, and reverse the MCAS trim commands. If it was working as advertised, then the crew wasn't flying the airplane, it was flying them. Thats another training or experience issue.

But again, the full CVR transcripts, and final reports should clear a bunch of this up for everyone.


They were dealing with issues from the moment they took off. With multiple issues to deal with runaway stabiliser was down on the list. Pilot overload.


The issues they were dealing with prior to MCAS activation are ones any crew would be expected to handle -- they didn't.


Previous in this thread, a list was given of other 737 (mostly NG) incidents of AoA issues. And those crews (including US operators) pretty much did the same thing as the ET crew, right up to the point of MCAS kicking in.
Now I'm not claiming the ET crew did not do any thing wrong (way to early for such claims - as well as the opposite of course), but it does not seem to be a unique way of handling such situation, if I understand things correctly.
Upto the point of MCAS activation, things seems to be pretty much under control for the ET crew.
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 3:34 pm

morrisond wrote:
PW100 wrote:
morrisond wrote:

All underwing planes pitch up when power is applied. That is not the issue. When you are approaching stall - because of the extra nacelle lift the controls get slightly light - not really causing any safety issues but not allowed by the FAR's.

Because of the higher mounting of the MAX engines the Pitch up effect due to power should be less than the NG.


. . . not really causing any safety issues but not allowed by the FAR's. Contradictio in terminis.

The FAR's are there to guarantee a standard of safety?

Having insufficient pitch stability margin (in some part of the flight envelope) seems to be pretty much safety related.


So how many MAX's do you think would actually get into a stall and crash if they didn't have MCAS? They would have to pull through this slightly light area of control force, ignore the stick shaker, the warning alarms and the frame buffeting for probably 10-20 seconds before entering an actual stall and then not be able to recover it - which should be achievable by any commercial pilot.


I have no idea. Do you?

What is the certification standard for such event? 1 E-10 or something like that?

How would you go about convincing FAA (and EASA, TCCA etc) that such event is so extremely rare, that it doesn not need to be taken into account in the design?

Again, I don't know. Do you?

But the FACT that 1) a FAR was devised for such condition, and 2) Boeing did not request a waiver on said FAR, but instead went through the trouble of designing and implementing MCAS, tells me it is not an acceptable situation against today's standards. Perhaps 25 years ago it was acceptable, today it is not.
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 3:39 pm

7BOEING7 wrote:
RickNRoll wrote:
AABusDrvr wrote:

I will reserve judgement until the final reports are out, but it appears he isn't wrong. Why the Lion air crew didn't jump on the "RUNAWAY STABILIZER' NNC is an issue. On the 737, it's the only proper checklist to address any uncommanded and/or inappropriate movement of the stabilizer. If they didn't know that, it's a clear deficiency in their training.

The wildcard with ET in my mind is the normal stab trim system. Boeing states it will stop, and reverse the MCAS trim commands. If it was working as advertised, then the crew wasn't flying the airplane, it was flying them. Thats another training or experience issue.

But again, the full CVR transcripts, and final reports should clear a bunch of this up for everyone.


They were dealing with issues from the moment they took off. With multiple issues to deal with runaway stabiliser was down on the list. Pilot overload.


The issues they were dealing with prior to MCAS activation are ones any crew would be expected to handle -- they didn't.

4 crews 'handled' it' (as you say) in the same way i.e. they did handle it. 3 crews got into difficulty only when MCAS activated. 1 only was saved.

Ray
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 3:44 pm

Seems we are forgetting that the MCAS in both crashes was preceded by some failure in the AOA sensors, other than talk about single sensor, one can get the impression from all the comments that MCAS version any kicks in without any trigger event.
One can assume that since there is very little talk about sensor failure, that the fix to that is simple and folks have moved on?
 
kalvado
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 3:45 pm

7BOEING7 wrote:
RickNRoll wrote:
AABusDrvr wrote:

I will reserve judgement until the final reports are out, but it appears he isn't wrong. Why the Lion air crew didn't jump on the "RUNAWAY STABILIZER' NNC is an issue. On the 737, it's the only proper checklist to address any uncommanded and/or inappropriate movement of the stabilizer. If they didn't know that, it's a clear deficiency in their training.

The wildcard with ET in my mind is the normal stab trim system. Boeing states it will stop, and reverse the MCAS trim commands. If it was working as advertised, then the crew wasn't flying the airplane, it was flying them. Thats another training or experience issue.

But again, the full CVR transcripts, and final reports should clear a bunch of this up for everyone.


They were dealing with issues from the moment they took off. With multiple issues to deal with runaway stabiliser was down on the list. Pilot overload.


The issues they were dealing with prior to MCAS activation are ones any crew would be expected to handle -- they didn't.

They may not handle those to the letter of the book, but I don't believe there was a potential o crash from those. Moreover, what ET did may possibly be describe as being to the spirit of SOP rather than the letter. And I didn't see any assumption that there was a crash potential from those deviations - moreover, people speculate that they would be able to complete the flight.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 3:45 pm

par13del wrote:
kalvado wrote:
So far, certification review is the words I heard - but I wonder if there is anything specific they're looking at.

So they are just going to do certification review in the hope that they will find something to review?


I don't think certification review looks like this. There has to be very long paper or electronic trail of all decisions regarding the 737MAX. Given the highly suspicious decision to certify MCAS 1.0, the revision would need to check:

1) What is the paper trail regarding MCAS, are there any anomalies (missing documents, missing data, approval-shopping, etc). If any of this is found then
2) examination of the WHOLE 737MAX certification process for signs of the same anomalies is probably highly needed, to find any other potential MCAS-like gremlins.

If MCAS certification was all good then the procedure for certification would really need to be changed, since it resulted in 350 dead (but this could be done after MAX is in the air again).
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 3:51 pm

par13del wrote:
Seems we are forgetting that the MCAS in both crashes was preceded by some failure in the AOA sensors, other than talk about single sensor, one can get the impression from all the comments that MCAS version any kicks in without any trigger event.
One can assume that since there is very little talk about sensor failure, that the fix to that is simple and folks have moved on?


Failure in AoA sensors is expected (sooner or later), but it should not lead to 2 crashes. At most, Boeing would be on the hook for poor quality of the sensor/airplane ($$$, warranty, compensation for downtime), but single AoA sensor failure should not be critical fault, ever. Pitot tubes can freeze, wasps can make nests in them, bird strike can disable them, and are actually a critical instrument. But again single pitot tube failure is not critical, because aircraft design should be robust to that.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 3:54 pm

par13del wrote:
Seems we are forgetting that the MCAS in both crashes was preceded by some failure in the AOA sensors, other than talk about single sensor, one can get the impression from all the comments that MCAS version any kicks in without any trigger event.
One can assume that since there is very little talk about sensor failure, that the fix to that is simple and folks have moved on?

AoA sensors are fragile, exposed to airflow, and they WILL fail once in a while. So design should be such that the failure doesn't cause any seriuos consequencies. Ideally, redundancy should kick in and the only extra thing crew should do is write a "please fix" note to maintenance. Same goes for numerous other systems.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 4:01 pm

kalvado wrote:
par13del wrote:
Seems we are forgetting that the MCAS in both crashes was preceded by some failure in the AOA sensors, other than talk about single sensor, one can get the impression from all the comments that MCAS version any kicks in without any trigger event.
One can assume that since there is very little talk about sensor failure, that the fix to that is simple and folks have moved on?

AoA sensors are fragile, exposed to airflow, and they WILL fail once in a while. So design should be such that the failure doesn't cause any seriuos consequencies. Ideally, redundancy should kick in and the only extra thing crew should do is write a "please fix" note to maintenance. Same goes for numerous other systems.


This^^^^ x1000
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 4:02 pm

Except most of what is being talked about is just MCAS, so has fixes been put in place or recommended that no one is concerned about sensor failure anymore and its effect on the 737?
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 4:25 pm

morrisond wrote:
Because of the higher mounting of the MAX engines the Pitch up effect due to power should be less than the NG.

Can you quote a source that agree with your claim ? Because any document Is have read so far are pointing to an INCREASE of the pitch up moment on the 737-8/9 MAX.

My understanding is that the main cause is the more forward location of the engines respective to the lift vector origin of the wings.When that distance increase the pitch up moment increase as well, especially on a 737-8/9 MAX at high angle of attack according to many sources.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 4:35 pm

PixelFlight wrote:
morrisond wrote:
Because of the higher mounting of the MAX engines the Pitch up effect due to power should be less than the NG.

Can you quote a source that agree with your claim ? Because any document Is have read so far are pointing to an INCREASE of the pitch up moment on the 737-8/9 MAX.

My understanding is that the main cause is the more forward location of the engines respective to the lift vector origin of the wings.When that distance increase the pitch up moment increase as well, especially on a 737-8/9 MAX at high angle of attack according to many sources.

My understanding that this is NOT because engines are mounted higher.
But engines ar mounted further forward, and I believe at some angle to aircraft axis. Forward placement of engines, and nacelle generated lift at higher AoA, are the most quoted reasons for pitch up momentum.
If (I am not positive here) engines are indeed tilted (1.5 degree, I believe) with intake higher off the ground, that by itself creates a pitch-up component of thrust.
THen a flow of exhaust air from the fan around the wing - and POSSIBLY (I am not positive) there is part of flow going above the wing, although that would be strange - may be yet another contributing factor.

Shows how complicated aerodynamics can be even before any numbers get crunched...
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 5:04 pm

morrisond wrote:
marcelh wrote:
morrisond wrote:

Well then you would have to redesign most of the control surfaces on all Commercial Aircraft - not many of them are going to be that effective beyond Vmo. There is a reason there is a Vmo limit.

Still blaming the pilots?


Nope 60-80% Boeing as I have said multiple times. I'm just getting sick of typing - "It's mainly Boeing's fault - however the accidents have also exposed some real deficiencies in Pilot training that need to be addressed as well"

Although I understand the deficiencies in pilot training, I’m still surprised that those deficiencies only popped up by crashing the MAX.
 
OldAeroGuy
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 5:09 pm

XRAYretired wrote:
4 crews 'handled' it' (as you say) in the same way i.e. they did handle it. 3 crews got into difficulty only when MCAS activated. 1 only was saved.

Ray


If you're including the Sunwings crew as 1 of the 4, they were not in the same situation Flaps down. The MAX crews had continuous stick shaker. Sunwings had two stick shaker events, one of 6 seconds (not recorded by FDR) and one of 3 seconds. Sunwings crew had no stick shaker when they retracted Flaps.

Another major difference is that Sunwings performed the "Unreliable Airspeed" NNC.

There is no evidence to date that JT610 or ET302 did so with Flaps down. Once MCAS kicked in Flaps up, they were too busy to do so.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
morrisond
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 5:12 pm

PixelFlight wrote:
morrisond wrote:
Because of the higher mounting of the MAX engines the Pitch up effect due to power should be less than the NG.

Can you quote a source that agree with your claim ? Because any document Is have read so far are pointing to an INCREASE of the pitch up moment on the 737-8/9 MAX.

My understanding is that the main cause is the more forward location of the engines respective to the lift vector origin of the wings.When that distance increase the pitch up moment increase as well, especially on a 737-8/9 MAX at high angle of attack according to many sources.


The effect due to power should be less but that does not mean that the Aerodynamic Lift of the larger Nacelle would be less.

The poster said it was because of power.
 
XRAYretired
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 5:23 pm

OldAeroGuy wrote:
XRAYretired wrote:
4 crews 'handled' it' (as you say) in the same way i.e. they did handle it. 3 crews got into difficulty only when MCAS activated. 1 only was saved.

Ray


If you're including the Sunwings crew as 1 of the 4, they were not in the same situation Flaps down. The MAX crews had continuous stick shaker. Sunwings had two stick shaker events, one of 6 seconds (not recorded by FDR) and one of 3 seconds. Sunwings crew had no stick shaker when they retracted Flaps.

Another major difference is that Sunwings performed the "Unreliable Airspeed" NNC.

There is no evidence to date that JT610 or ET302 did so with Flaps down. Once MCAS kicked in Flaps up, they were too busy to do so.



They reacted in the same way. You have no evidence to suggest they did not apply Unreliable Airspeed. The evidence we have would suggest they did.

You offer no alternative. Just say they were wrong.

Ray
 
morrisond
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 5:25 pm

PW100 wrote:
morrisond wrote:
PW100 wrote:

. . . not really causing any safety issues but not allowed by the FAR's. Contradictio in terminis.

The FAR's are there to guarantee a standard of safety?

Having insufficient pitch stability margin (in some part of the flight envelope) seems to be pretty much safety related.


So how many MAX's do you think would actually get into a stall and crash if they didn't have MCAS? They would have to pull through this slightly light area of control force, ignore the stick shaker, the warning alarms and the frame buffeting for probably 10-20 seconds before entering an actual stall and then not be able to recover it - which should be achievable by any commercial pilot.


I have no idea. Do you?

What is the certification standard for such event? 1 E-10 or something like that?

How would you go about convincing FAA (and EASA, TCCA etc) that such event is so extremely rare, that it doesn not need to be taken into account in the design?

Again, I don't know. Do you?

But the FACT that 1) a FAR was devised for such condition, and 2) Boeing did not request a waiver on said FAR, but instead went through the trouble of designing and implementing MCAS, tells me it is not an acceptable situation against today's standards. Perhaps 25 years ago it was acceptable, today it is not.



I would say the odds of a crash of a MAX without MCAS due to a stall would be about Zero. A non-pilot could learn in about 5 minutes how to avoid the stall - it is the most basic and easily achieved maneuver - easier than keeping the plane straight and level.

If the controls went negative pressure then that would be a safety issue - but they barely get below the acceptable limit.

I believe they didn't go for the FAR exception route (even if Possible) as that would have led to the circular loop of requiring simulator training which there customers said was a big no-no.

It should have been an easy software fix and unfortunately it appears that Boeing put about as much effort into it as the safety increase it would provide vs having no MCAS.
 
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Revelation
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 5:52 pm

AVGeekNY wrote:
Thank you for answering. Our credentials are perhaps somewhat similar. I'm PPL, engineering and software. Did you actually watch the 60 minutes Australia? Also suggest that you read the article I linked by Greg Travis. You may find them informative and interesting.

Obviously what Boeing did was an epic fail. I'm not trusting of what was rolled out. Sounds borderline criminal to me. The AA pilots don't sound like they are in any hurry to trust anything from Boeing. If a plane needs MCAS to be safe then the plane may not be so good, at least not as a 737.

I'm having a hard time putting what you said together. If you have a PPL you should have a pretty good idea of what it takes to get an airplane to stall. You really have to go far out to the edges of the flight envelope to make that happen in a trainer never mind a commercial airliner. It's only in that regime where the nacelle lift comes in to play, and it's only that part of the regime that MCAS is needed to meet regulations on linearity of the control column movement.

If you have a PPL you have a pretty good idea how to cross check instruments and how to rule out which ones are giving you unrealistic info and how to fall back on basics of pitch and power especially on CAVOK days like both of these crashes were.

I have a hard time understanding how two pilots with ATPLs can lose situational awareness to the point of finding themselves in that part of the flight envelope and needing to then figure out how to do the runaway stab checklist when they really should not have been there in the first place.

I do understand the goal is to make things as easy as they can for the pilots and that Boeing did a poor job on implementing MCAS but to say MAX needs MCAS to be safe over states the situation, IMHO. I doubt these two crew's abilities to handle many other failure modes that they should be able to handle.

AVGeekNY wrote:
My prediction is that this thing continues to get uglier by the day and it's just getting started. I bet we're 6 months if ever before it flys again.

Both the NYT and the BBC reports provide AA's comments:

American Airlines said it was "confident that the impending software updates, along with the new training elements Boeing is developing for the Max, will lead to recertification of the aircraft soon."

So those pilots will really have to put it on the line to avoid flying MAX in the relatively near future.

Chances are most pilots will be fine with flying the MAX once it's recertified and this will fade away just like every other past air disaster has.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
OldAeroGuy
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 5:57 pm

XRAYretired wrote:
You have no evidence to suggest they did not apply Unreliable Airspeed. The evidence we have would suggest they did.

Ray


Please provide evidence the ET302 crew performed the "Airspeed Unreliable" NNC.

I don't see it in the FDR data.

Thanks, OAG
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
XRAYretired
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 6:09 pm

morrisond wrote:
PW100 wrote:
morrisond wrote:

So how many MAX's do you think would actually get into a stall and crash if they didn't have MCAS? They would have to pull through this slightly light area of control force, ignore the stick shaker, the warning alarms and the frame buffeting for probably 10-20 seconds before entering an actual stall and then not be able to recover it - which should be achievable by any commercial pilot.


I have no idea. Do you?

What is the certification standard for such event? 1 E-10 or something like that?

How would you go about convincing FAA (and EASA, TCCA etc) that such event is so extremely rare, that it doesn not need to be taken into account in the design?

Again, I don't know. Do you?

But the FACT that 1) a FAR was devised for such condition, and 2) Boeing did not request a waiver on said FAR, but instead went through the trouble of designing and implementing MCAS, tells me it is not an acceptable situation against today's standards. Perhaps 25 years ago it was acceptable, today it is not.



I would say the odds of a crash of a MAX without MCAS due to a stall would be about Zero. A non-pilot could learn in about 5 minutes how to avoid the stall - it is the most basic and easily achieved maneuver - easier than keeping the plane straight and level.

If the controls went negative pressure then that would be a safety issue - but they barely get below the acceptable limit.

I believe they didn't go for the FAR exception route (even if Possible) as that would have led to the circular loop of requiring simulator training which there customers said was a big no-no.

It should have been an easy software fix and unfortunately it appears that Boeing put about as much effort into it as the safety increase it would provide vs having no MCAS.


Can I suggest a slightly different line to follow. Many have been corralled by the idea that the potential for Sim training was the prime driver in MCAS design/hidden function aspect of our problem. Perhaps it is the requirement for 'no type change' that we ought to be looking at and in particular how much change would require a type change.

Is it possible that a two sensor MCAS -effectively a new system- was perceived to maybe require a type change? So single sensor was chosen so it could be passed off as a minor update to STS? The need for MCAS was not perhaps recognised until after a tacit agreement had been reached on the amount of change that would be allowable to introduce MAX without a type change had been made with FAA? Waiver to the FAR requirement not being allowable without a type change maybe?

Type change would likely have required Sim training anyway (as well as type cert, pilot and MX rating).

Ray
 
XRAYretired
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 6:22 pm

OldAeroGuy wrote:
XRAYretired wrote:
You have no evidence to suggest they did not apply Unreliable Airspeed. The evidence we have would suggest they did.

Ray


Please provide evidence the ET302 crew performed the "Airspeed Unreliable" NNC.

I don't see it in the FDR data.

Thanks, OAG

Please provide evidence that ET302 were not.
Please speculate what it was they were doing if not Airspeed Unreliable (cup of coffee, waiting for a bloke in a cloak to turn up?)

Ray
 
morrisond
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 6:24 pm

XRAYretired wrote:
OldAeroGuy wrote:
XRAYretired wrote:
You have no evidence to suggest they did not apply Unreliable Airspeed. The evidence we have would suggest they did.

Ray


Please provide evidence the ET302 crew performed the "Airspeed Unreliable" NNC.

I don't see it in the FDR data.

Thanks, OAG

Please provide evidence that ET302 were not.
Please speculate what it was they were doing if not Airspeed Unreliable (cup of coffee, waiting for a bloke in a cloak to turn up?)

Ray


Trying to get the Auto-Pilot to fly it for them as they didn't seem to have much clue how to fly the plane manually?

Yes - I'm being snarky but it's not out of the realm of possibility.
 
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keesje
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 6:25 pm

Weeks after the first fatal crash of the 737 MAX, pilots from American Airlines pressed Boeing executives to work urgently on a fix. In a closed-door meeting, they even argued that Boeing should push authorities to take an emergency measure that would likely result in the grounding of the MAX.

The Boeing executives resisted.

Mike Sinnett, a vice president at Boeing, acknowledged that the manufacturer was assessing potential design flaws with the plane, including new anti-stall software. But he balked at taking a more aggressive approach, saying it was not yet clear that the new system was to blame for the Lion Air crash, which killed 189 people.

“No one has yet to conclude that the sole cause of this was this function on the airplane,” Sinnett said, according to a recording of the Nov. 27 meeting reviewed by The New York Times.


https://www.seattletimes.com/business/b ... n-737-max/

It seems the ones telling us to stop speculation, wait for the official investigation report, while pointing out Lionair's operational track record and repeating Boeing's observation on the aircraft airworthiness, need to pause and re-think. How loyalty & selectively following the rules can cause you being used, ending up on the wrong side of history.
Last edited by keesje on Wed May 15, 2019 6:28 pm, edited 2 times in total.
"Never mistake motion for action." Ernest Hemingway
 
morrisond
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 6:25 pm

XRAYretired wrote:
morrisond wrote:
PW100 wrote:

I have no idea. Do you?

What is the certification standard for such event? 1 E-10 or something like that?

How would you go about convincing FAA (and EASA, TCCA etc) that such event is so extremely rare, that it doesn not need to be taken into account in the design?

Again, I don't know. Do you?

But the FACT that 1) a FAR was devised for such condition, and 2) Boeing did not request a waiver on said FAR, but instead went through the trouble of designing and implementing MCAS, tells me it is not an acceptable situation against today's standards. Perhaps 25 years ago it was acceptable, today it is not.



I would say the odds of a crash of a MAX without MCAS due to a stall would be about Zero. A non-pilot could learn in about 5 minutes how to avoid the stall - it is the most basic and easily achieved maneuver - easier than keeping the plane straight and level.

If the controls went negative pressure then that would be a safety issue - but they barely get below the acceptable limit.

I believe they didn't go for the FAR exception route (even if Possible) as that would have led to the circular loop of requiring simulator training which there customers said was a big no-no.

It should have been an easy software fix and unfortunately it appears that Boeing put about as much effort into it as the safety increase it would provide vs having no MCAS.


Can I suggest a slightly different line to follow. Many have been corralled by the idea that the potential for Sim training was the prime driver in MCAS design/hidden function aspect of our problem. Perhaps it is the requirement for 'no type change' that we ought to be looking at and in particular how much change would require a type change.

Is it possible that a two sensor MCAS -effectively a new system- was perceived to maybe require a type change? So single sensor was chosen so it could be passed off as a minor update to STS? The need for MCAS was not perhaps recognised until after a tacit agreement had been reached on the amount of change that would be allowable to introduce MAX without a type change had been made with FAA? Waiver to the FAR requirement not being allowable without a type change maybe?

Type change would likely have required Sim training anyway (as well as type cert, pilot and MX rating).

Ray


Totally possible.
 
OldAeroGuy
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 6:59 pm

XRAYretired wrote:
OldAeroGuy wrote:
XRAYretired wrote:
You have no evidence to suggest they did not apply Unreliable Airspeed. The evidence we have would suggest they did.

Ray


Please provide evidence the ET302 crew performed the "Airspeed Unreliable" NNC.

I don't see it in the FDR data.

Thanks, OAG

Please provide evidence that ET302 were not.
Please speculate what it was they were doing if not Airspeed Unreliable (cup of coffee, waiting for a bloke in a cloak to turn up?)

Ray


The Flaps down "Airspeed Unreliable" NNC starts with:
- N1 @ 80%
- 10 deg pitch attitude

Neither of these actions was taken.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
AABusDrvr
Posts: 24
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 7:28 pm

SEU wrote:
morrisond wrote:
XRAYretired wrote:
Please provide evidence that ET302 were not.
Please speculate what it was they were doing if not Airspeed Unreliable (cup of coffee, waiting for a bloke in a cloak to turn up?)

Ray


Trying to get the Auto-Pilot to fly it for them as they didn't seem to have much clue how to fly the plane manually?

Yes - I'm being snarky but it's not out of the realm of possibility.


Who the hell are you to say what those pilots did and did not know. The plane was out of control. It was a horrible situation to be in.


The airplane wasn’t anywhere near “out of control” until the very end.

I’m looking at my 737 QRH “Airspeed Unreliable” check list right now. The first two actions are:

1. Autopilot (If engaged)...Disengage.
2. Autothrottle (If engaged)....Disengage.

The fact they tried, repeatedly, to engage the autopilot, and probably never disengaged the autothrottle, is a pretty clear indication they never did the checklist.
 
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PixelFlight
Posts: 348
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 8:26 pm

morrisond wrote:
PixelFlight wrote:
morrisond wrote:
Because of the higher mounting of the MAX engines the Pitch up effect due to power should be less than the NG.

Can you quote a source that agree with your claim ? Because any document Is have read so far are pointing to an INCREASE of the pitch up moment on the 737-8/9 MAX.

My understanding is that the main cause is the more forward location of the engines respective to the lift vector origin of the wings.When that distance increase the pitch up moment increase as well, especially on a 737-8/9 MAX at high angle of attack according to many sources.


The effect due to power should be less but that does not mean that the Aerodynamic Lift of the larger Nacelle would be less.

The poster said it was because of power.

Again can you quote a source that agree with your claim ? A moment need a position vector (wings lift) and a force vector (engines power). As the 737-8/9 MAX wings are not significantly different than the 737-800/900 NG wings, only the engines location can explain the pitch up moment increase.
 
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InsideMan
Posts: 286
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 8:31 pm

Revelation wrote:
AVGeekNY wrote:
I think it's pretty clear that any airplane that pitches up so significantly when power is applied that it needs a computer to avoid a stall because it doesn't fly like other 737s sounds like a serious issue.

The situation that triggers MCAS is not typically triggered by the application of power.

AVGeekNY wrote:
Are you a 737 pilot?

No, [...].


Everything past that is irrelevant.
Why is it that all the armchair pilots on here believe they know better than trained 737 pilots with years of experience?
 
morrisond
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 8:37 pm

Ignoring the Aerodynamic effects - a higher mounted engine will have less of a pitch up effect as it is closer to in-line with the COG.

If they were mounted 1 M lower that would have a bigger effect as the engines would effectively want to pivot around the COG.
 
morrisond
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 8:57 pm

InsideMan wrote:
Revelation wrote:
AVGeekNY wrote:
I think it's pretty clear that any airplane that pitches up so significantly when power is applied that it needs a computer to avoid a stall because it doesn't fly like other 737s sounds like a serious issue.

The situation that triggers MCAS is not typically triggered by the application of power.

AVGeekNY wrote:
Are you a 737 pilot?

No, [...].


Everything past that is irrelevant.
Why is it that all the armchair pilots on here believe they know better than trained 737 pilots with years of experience?


You obviously haven't looked at the Flight Experience of the ET302 crew - both let into the cockpit of a 737 with only a few hundred hours. The pilot has a bunch of hours but the co-pilot was very low hour and seemed to know more than the pilot. He had less than two months in the 737.
 
MartijnNL
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 9:25 pm

AVGeekNY wrote:
My confidence and trust is forever shaken in Boeing. After watching the 60 minutes Australia, reading commentary from pilots and this article https://medium.com/@gregoryreedtravis/t ... b1869839b6 I don't know how the Max could ever be trusted.

I feel exactly the same. And I think many people do. After visiting the Boeing factory in Everett I used to wear my Boeing cap with pride. Nowadays I leave it at home to avoid remarks from friends, co-workers and the man in the street.

AVgeekNY wrote:
A question for 737 pilots, if the need for MCAS was driven by quirky aerodynamics then why should we even trust the aircraft design?

Revelation wrote:
Seems the media has done its job in getting you agitated.

That's not the job of the media. It's their job to inform us by reporting facts and opinions.

Revelation wrote:
Didn't you take away from all of that viewing that those "quirky aerodynamics" only happened when the airplane was approaching the stall condition?

That's not the point. Boeing installed a new system in the latest 737 version and didn't tell anybody about it.

Revelation wrote:
Didn't you wonder why in both crashes the pilots didn't respond to the stick shaker telling them they were heading towards a stall in a timely fashion?

I think the pilot in the simulator on 60 minutes gave an excellent explanation of what happened in the cockpits of the two flights that crashed.
 
Amexair
Posts: 52
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 9:29 pm

morrisond wrote:
Trying to get the Auto-Pilot to fly it for them as they didn't seem to have much clue how to fly the plane manually?

Yes - I'm being snarky but it's not out of the realm of possibility.


That's a really uneducated comment. Clearly, the reason why we need to wait for the full report before making a conclusion.

But I can make one logical conclusion - Activating the Autopilot frees up capacity so the pilots can concentrate on assessing, navigation and planning. A Standard procedure even during a major failure such as an engine flame-out.
 
smartplane
Posts: 767
Joined: Fri Aug 03, 2018 9:23 pm

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 9:29 pm

AVGeekNY wrote:
My confidence and trust is forever shaken in Boeing. After watching the 60 minutes Australia, reading commentary from pilots and this article https://medium.com/@gregoryreedtravis/t ... b1869839b6 I don't know how the Max could ever be trusted.

A question for 737 pilots, if the need for MCAS was driven by quirky aerodynamics then why should we even trust the aircraft design?

The article is a good, clear summary.

Given the MAX is the latest incarnation of the 100/200, would be great if an experienced 100/200 and MAX pilot could share the real life magnitude of the differences in flying characteristics. Won't happen, presumably because Boeing has reminded customers of implied and explicit confidentiality (including interfering with a federal investigation), and in turn airlines have advised their staff.

One defect with 4 aircraft generations of 737, is the latest iteration uses the previous iteration as the baseline (plus scaling), not the 100/200 for which the original type certificate is held. STC's should be capped at two or maybe three generations.
 
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PixelFlight
Posts: 348
Joined: Thu Nov 08, 2018 11:09 pm

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Wed May 15, 2019 9:50 pm

morrisond wrote:
Ignoring the Aerodynamic effects - a higher mounted engine will have less of a pitch up effect as it is closer to in-line with the COG.
If they were mounted 1 M lower that would have a bigger effect as the engines would effectively want to pivot around the COG.

Irrational, you simply can't ignore the aerodynamic wings lift to create a pitch up moment with engines mounted under the wings. This thread is about the 737-8/9 MAX, not about a hypothetical case. And your original claim was specifically about the 737-8/9 MAX, even if you deleted that reference in your response. I pretend that your claim was false because you missed to take in account the forward location of the engines that generate most of the pitch up moment on the 737-8/9 MAX.

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