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sgrow787
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 10:01 pm

PixelFlight wrote:
Trin wrote:
I do agree that the AOA sensor issue is starting to look more like something downstream of the actual vane itself. Which would also explain why Lion Air was repeatedly unable to rectify the issue despite replacing it in between flights.


Yes. Nobody have yet come up with a plausible technical scenario that fully fit the JT10 official public data (disagree before and after AOA replacement). Many here have searched, and the possibility that the problem was in the ADIRU or FCC was raised since months, but lack of public information about it makes hard to refine this scenario. The best description I have found yet of the FCC internals is still this one:

https://www.satcom.guru/2018/11/737-fcc ... mmand.html

If someone have spot something better, please post it.


Thanks for posting that. The problems with ADIRU documented on Wikipedia, IIRC, included gyro issues.

FAA Airworthiness directive 2000-07-27
On May 3, 2000, the FAA issued airworthiness directive 2000-07-27, addressing dual critical failures during flight, attributed to power supply issues affecting early Honeywell HG2030 and HG2050 ADIRU ring laser gyros used on several Boeing 737, 757, Airbus A319, A320, A321, A330, and A340 models.[2][12][13]


This explains why the SMYD system diagram on Peter's website shows the ADIRU producing roll rate, roll angle, lateral acceleration. The ADIRU must have a gyro internal or data received from an external gyro. I guess I'll find out how a Yaw Damper system (aka SMYD) affects pitch (lateral axis) after reading Peter's description.

So, assuming the ADIRU contains a gyro for pitch, a gyro for roll, and a gyro for yaw, does this support a root ADIRU issue affecting roll out and takeoff?

Finally, one has to wonder what the outcome would be in all this had (assuming it's ADIRU/power issue) the ADIRU/AOA/airspeed data never failed. Would anyone ever know about MCAS? Would it be touted as this wonderful new system that makes flying the 737 easier (compared to the NG)? Obviously things fail eventually, but it isn't inconceivable to see a situation where an AOA/airspeed/ADIRU failure doesn't happen until 5+ years into a new plane's lifetime.

But let's just state right now, since we're in the middle of an impending software patch from Boeing, the only way the Max gets up into the sky again is:
(1) Either the MCAS is updated to look at 2 or more redundant AOA/airspeed sensors, or a redundancy is inserted in a system feeding the MCAS
(2) The sensing system itself, whether the AOA sensors themselves, or the ADIRUs, or the power bus supporting the ADIRUs, has to be addressed
(3) The current AD for disabling the MCAS in the case of a cyclic runaway trim, remains (for the remote case of now two sensors going bad simultaneously)
(4) The above I would expect to take 6 months to a year, on what is there currently to work with (shorter if it's a software thing, longer if it included wiring sensors and fixing a power issue)
Last edited by sgrow787 on Sun Mar 17, 2019 10:23 pm, edited 4 times in total.
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Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
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dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 10:14 pm

Backseater wrote:
One simple question:
Isn’t a detected approach to stall conditions just a transient event?
If so, does MCAS ever undo what it just did? I.e. stab trim from o to -2.5 and at some later time back to 0?

My guess is that in an actual near stall event it wouldn't move the stab the full 2.5 degrees. It's only going to trim down enough to reduce the AoA below whatever threshold and then it stops.
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Backseater
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 10:22 pm

Fine. But if the condition that triggered MCAS (probably exceeding AoA threshold as a function of Mach nr) disappears due to pilot input but reappears a moment later. Does MCAS starts as if nothing happened before?
 
N6168E
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 10:28 pm

Are the ADIRU's on the MAX the same as the NG or new and "Improved"?
 
lowbank
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 10:30 pm

dragon6172 wrote:
Backseater wrote:
One simple question:
Isn’t a detected approach to stall conditions just a transient event?
If so, does MCAS ever undo what it just did? I.e. stab trim from o to -2.5 and at some later time back to 0?

My guess is that in an actual near stall event it wouldn't move the stab the full 2.5 degrees. It's only going to trim down enough to reduce the AoA below whatever threshold and then it stops.


No what it says is if it trims 1 degree and the pilot resets it will then enact another 2.5 degrees, if reset again it will enact another 2.5 degrees. From what I read the trim can only go to 5 degrees total but MCAS will move to the total 5 degrees.
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flyingturtle
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 10:33 pm

Wow, that piece by Dominic Gates is damning.

Nuke Boeing from orbit. It's the only way to be safe.


David
Last edited by flyingturtle on Sun Mar 17, 2019 10:51 pm, edited 1 time in total.
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spacecadet
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 10:44 pm

lowbank wrote:
dragon6172 wrote:
Backseater wrote:
One simple question:
Isn’t a detected approach to stall conditions just a transient event?
If so, does MCAS ever undo what it just did? I.e. stab trim from o to -2.5 and at some later time back to 0?

My guess is that in an actual near stall event it wouldn't move the stab the full 2.5 degrees. It's only going to trim down enough to reduce the AoA below whatever threshold and then it stops.


No what it says is if it trims 1 degree and the pilot resets it will then enact another 2.5 degrees, if reset again it will enact another 2.5 degrees. From what I read the trim can only go to 5 degrees total but MCAS will move to the total 5 degrees.


That's an extremely dumb system if that's the way it works, in more ways than one. I have a hard time believing it does work that way, because a) you'd have to be an outright idiot to not see how that wouldn't have potentially catastrophic safety implications, and b) simply rechecking the data a few times a second to stop trimming where it needs to instead of the full 2.5 degrees would be a trivial addition to the programming. Essentially this would be like having an auto-pilot that's designed to just pitch up the plane 2.5 degrees every time it's engaged, regardless of the current attitude. Makes no sense.
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PW100
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 10:50 pm

lowbank wrote:
ciaran wrote:

I am stunned that safety reports were not updated and risk reviews not updated and the risk upgraded when the amount of movement was increased from 0.6 to 2.5. In any risk review I have ever been in that would have been the big debate, did that number increase the risk and should the risk category be increased.

We also do DFMEA’s , design failure mode and effect analysis. That should have brought out the fact that the MCAS had no limit to its movement. If I had not updated those documents on any project I worked on I would be expecting a jail sentence based on professional negligence.

One of my sayings and I do say it in meeting as it’s part of our code of conduct. Can I defend myself in a court of law with what I have put in this document.

There are going to be some very scared Engineers if that article is true.


Not to mention the delegated certifying staff (on Boeing's roster) who signed of on FAA behalf . . .
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LDRA
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 11:00 pm

Aerospace engineers are over worked and under conpensated for their responsibilities, something somewhere is got to give
 
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TWA302
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 11:09 pm

ciaran wrote:


If all this reporting is factual, it is very disturbing. Wow, just wow. I have been on 57 MAX8 flights on WN and never had a concern. Now, reading this I just don't know what to say.
 
lowbank
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 11:10 pm

spacecadet wrote:
lowbank wrote:
dragon6172 wrote:
My guess is that in an actual near stall event it wouldn't move the stab the full 2.5 degrees. It's only going to trim down enough to reduce the AoA below whatever threshold and then it stops.


No what it says is if it trims 1 degree and the pilot resets it will then enact another 2.5 degrees, if reset again it will enact another 2.5 degrees. From what I read the trim can only go to 5 degrees total but MCAS will move to the total 5 degrees.


That's an extremely dumb system if that's the way it works, in more ways than one. I have a hard time believing it does work that way, because a) you'd have to be an outright idiot to not see how that wouldn't have potentially catastrophic safety implications, and b) simply rechecking the data a few times a second to stop trimming where it needs to instead of the full 2.5 degrees would be a trivial addition to the programming. Essentially this would be like having an auto-pilot that's designed to just pitch up the plane 2.5 degrees every time it's engaged, regardless of the current attitude. Makes no sense.


Just quoting the article.
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TWA302
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 11:14 pm

LDRA wrote:
Aerospace engineers are over worked and under conpensated for their responsibilities, something somewhere is got to give


Average of $107k is underpaid?
 
LDRA
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 11:14 pm

spacecadet wrote:
lowbank wrote:
dragon6172 wrote:
My guess is that in an actual near stall event it wouldn't move the stab the full 2.5 degrees. It's only going to trim down enough to reduce the AoA below whatever threshold and then it stops.


No what it says is if it trims 1 degree and the pilot resets it will then enact another 2.5 degrees, if reset again it will enact another 2.5 degrees. From what I read the trim can only go to 5 degrees total but MCAS will move to the total 5 degrees.


That's an extremely dumb system if that's the way it works, in more ways than one. I have a hard time believing it does work that way, because a) you'd have to be an outright idiot to not see how that wouldn't have potentially catastrophic safety implications, and b) simply rechecking the data a few times a second to stop trimming where it needs to instead of the full 2.5 degrees would be a trivial addition to the programming. Essentially this would be like having an auto-pilot that's designed to just pitch up the plane 2.5 degrees every time it's engaged, regardless of the current attitude. Makes no sense.


Part of the problem is trim actuator is extremely slow comparing to aircraft pitch response time constant. So MCAS is severely restricted in controller output bandwidth
 
LDRA
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 11:20 pm

TWA302 wrote:
LDRA wrote:
Aerospace engineers are over worked and under conpensated for their responsibilities, something somewhere is got to give


Average of $107k is underpaid?


Absolutely! For the level and breadth of experience required and responsibility that carries.
 
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glideslope
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 11:50 pm

PW100 wrote:
lowbank wrote:
ciaran wrote:

I am stunned that safety reports were not updated and risk reviews not updated and the risk upgraded when the amount of movement was increased from 0.6 to 2.5. In any risk review I have ever been in that would have been the big debate, did that number increase the risk and should the risk category be increased.

We also do DFMEA’s , design failure mode and effect analysis. That should have brought out the fact that the MCAS had no limit to its movement. If I had not updated those documents on any project I worked on I would be expecting a jail sentence based on professional negligence.

One of my sayings and I do say it in meeting as it’s part of our code of conduct. Can I defend myself in a court of law with what I have put in this document.

There are going to be some very scared Engineers if that article is true.


Not to mention the delegated certifying staff (on Boeing's roster) who signed of on FAA behalf . . .


Over 60% was completed by Boeing alone. The FAA should be criminally liable for allowing this.
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GalaxyFlyer
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 12:09 am

glideslope wrote:
PW100 wrote:
lowbank wrote:
I am stunned that safety reports were not updated and risk reviews not updated and the risk upgraded when the amount of movement was increased from 0.6 to 2.5. In any risk review I have ever been in that would have been the big debate, did that number increase the risk and should the risk category be increased.

We also do DFMEA’s , design failure mode and effect analysis. That should have brought out the fact that the MCAS had no limit to its movement. If I had not updated those documents on any project I worked on I would be expecting a jail sentence based on professional negligence.

One of my sayings and I do say it in meeting as it’s part of our code of conduct. Can I defend myself in a court of law with what I have put in this document.

There are going to be some very scared Engineers if that article is true.


Not to mention the delegated certifying staff (on Boeing's roster) who signed of on FAA behalf . . .


Over 60% was completed by Boeing alone. The FAA should be criminally liable for allowing this.


Do you expect the FAA to hire, train and keep current an engineering and testing staff equal to the staffs of Airbus, Boeing, Bombardier, Dassault and Embraer plus the all Part 23 builders to run certification programs? Considering certification programs are not continuous, they’d be hired, the RIF’d only to be rehired for next program. Designated Engineering Representatives are a very tried and true means of certification. BTW, the builders will toss them in second if they screwed up. My experience at an OEM says DERs can be harder to get a sign from because of they aren’t FAA employees and lose their DER letter and can be fired from the builder.

GF
 
ccjohn
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 12:13 am

LDRA wrote:
TWA302 wrote:
LDRA wrote:
Aerospace engineers are over worked and under conpensated for their responsibilities, something somewhere is got to give


Average of $107k is underpaid?


Absolutely! For the level and breadth of experience required and responsibility that carries.


I work in excavation and trucking and my yearly salery is 82k. As far as I’m concerned an aerospace engineer making 107k can hardly afford a morgage payment as well as college debts. If they truly only make 107k I would say that’s severely underpaid
 
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Jouhou
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 12:14 am

TWA302 wrote:
LDRA wrote:
Aerospace engineers are over worked and under conpensated for their responsibilities, something somewhere is got to give


Average of $107k is underpaid?


Compared to business executives hell yes. They actually produce something valuable to society.
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 12:18 am

ccjohn wrote:
LDRA wrote:
TWA302 wrote:

Average of $107k is underpaid?


Absolutely! For the level and breadth of experience required and responsibility that carries.


I work in excavation and trucking and my yearly salery is 82k. As far as I’m concerned an aerospace engineer making 107k can hardly afford a morgage payment as well as college debts. If they truly only make 107k I would say that’s severely underpaid


Remember, it’s a very closed business. In the US, if you’re an aero engineer, you work for Boeing, Lockheed and maybe Cessna unless an international builder offers work. It’s a transient field as major design programs are maybe a twice or three times in a career. There’s a large build up in engineering talent hired prior to first flight, reducing as the test program ends, then potential unemployment. The 747 and 767 program hired lots of ex-Avro Arrow Canadian engineers, as did the Apollo program.

GF
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 1:22 am

Backseater wrote:
Fine. But if the condition that triggered MCAS (probably exceeding AoA threshold as a function of Mach nr) disappears due to pilot input but reappears a moment later. Does MCAS starts as if nothing happened before?

Yes.
lowbank wrote:
No what it says is if it trims 1 degree and the pilot resets it will then enact another 2.5 degrees, if reset again it will enact another 2.5 degrees. From what I read the trim can only go to 5 degrees total but MCAS will move to the total 5 degrees.

Negative. MCAS will stop inputs if the AoA is reduced below threshold.
spacecadet wrote:
That's an extremely dumb system if that's the way it works, in more ways than one. I have a hard time believing it does work that way, because a) you'd have to be an outright idiot to not see how that wouldn't have potentially catastrophic safety implications, and b) simply rechecking the data a few times a second to stop trimming where it needs to instead of the full 2.5 degrees would be a trivial addition to the programming. Essentially this would be like having an auto-pilot that's designed to just pitch up the plane 2.5 degrees every time it's engaged, regardless of the current attitude. Makes no sense.

It doesnt work that way. If it detects the aircraft has gone below whichever threshold, it will stop making inputs. It does not go the full 2.5 degrees each time. See below quote.


"The MCAS function becomes active when the airplane Angle of Attack exceeds a threshold based on airspeed and altitude. Stabilizer incremental commands are limited to 2.5 degrees and are provided at a rate of 0.27 degrees per second. The magnitude of the stabilizer input is lower at high Mach number and greater at low Mach numbers. The function is reset once angle of attack falls below the Angle of Attack threshold or if manual stabilizer commands are provided by the flight crew. If the original elevated AOA condition persists, the MCAS function commands another incremental stabilizer nose down command according to current aircraft Mach number at actuation."
Phrogs Phorever
 
weekendppl
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 1:39 am

flyingturtle wrote:
Nuke Boeing from orbit. It's the only way to be safe.

The hyperbole about this is getting a little much. Tens, more probably hundreds, of billions of passengers have safely completed travel on Boeing aircraft. Hundreds of thousands will do so today alone. No single company has contributed more to the worldwide air transportation system and the safety level that has made it possible. Yes, the fatalities from these two 737 Max 8 accidents are terrible and regrettable. I'm certain everybody in responsible engineering and management positions at Boeing familiar with the particulars of this situation, and how it came to be, knows, in hindsight, they could, should, have done better. (Their PR and Legal mavens won't let it be said out loud; though I would argue they might be better off in the long haul if they made a simply worded statement to this effect.)

But to think that somehow the world would be better off to give Boeing the death penalty over it, or abandon wholesale the present system for regulation and compliance certification over it, is just silly. What exactly would replace Boeing and the FAA? Something like the way Google, Tesla, Facebook develop and deploy product? I'll take Boeing and the FAA any day and 100 times on Saturday if that's the choice. These are all, at root, human systems. Human systems, at their best, will always occasionally fail. And, sadly, sometimes people will end up dead when they do. But the living learn, improve, and move on. When in human history has this not been how we have advanced?

(Full disclosure: I spent seven years of my long career working at a company partially owned by Boeing. I never worked in air transportation. I own investments in mutual funds that have, among other positions, positions in Boeing.)
 
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SuseJ772
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 1:52 am

weekendppl wrote:
flyingturtle wrote:
Nuke Boeing from orbit. It's the only way to be safe.

The hyperbole about this is getting a little much. Tens, more probably hundreds, of billions of passengers have safely completed travel on Boeing aircraft. Hundreds of thousands will do so today alone. No single company has contributed more to the worldwide air transportation system and the safety level that has made it possible. Yes, the fatalities from these two 737 Max 8 accidents are terrible and regrettable. I'm certain everybody in responsible engineering and management positions at Boeing familiar with the particulars of this situation, and how it came to be, knows, in hindsight, they could, should, have done better. (Their PR and Legal mavens won't let it be said out loud; though I would argue they might be better off in the long haul if they made a simply worded statement to this effect.)

But to think that somehow the world would be better off to give Boeing the death penalty over it, or abandon wholesale the present system for regulation and compliance certification over it, is just silly. What exactly would replace Boeing and the FAA? Something like the way Google, Tesla, Facebook develop and deploy product? I'll take Boeing and the FAA any day and 100 times on Saturday if that's the choice. These are all, at root, human systems. Human systems, at their best, will always occasionally fail. And, sadly, sometimes people will end up dead when they do. But the living learn, improve, and move on. When in human history has this not been how we have advanced?

(Full disclosure: I spent seven years of my long career working at a company partially owned by Boeing. I never worked in air transportation. I own investments in mutual funds that have, among other positions, positions in Boeing.)

This was very well said. The Seattle Times article is very bad, but we shouldn’t throw the baby out with the bath water and overreact.
Currently at PIE, requesting FWA >> >>
 
kalvado
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 1:55 am

SuseJ772 wrote:
weekendppl wrote:
flyingturtle wrote:
Nuke Boeing from orbit. It's the only way to be safe.

The hyperbole about this is getting a little much. Tens, more probably hundreds, of billions of passengers have safely completed travel on Boeing aircraft. Hundreds of thousands will do so today alone. No single company has contributed more to the worldwide air transportation system and the safety level that has made it possible. Yes, the fatalities from these two 737 Max 8 accidents are terrible and regrettable. I'm certain everybody in responsible engineering and management positions at Boeing familiar with the particulars of this situation, and how it came to be, knows, in hindsight, they could, should, have done better. (Their PR and Legal mavens won't let it be said out loud; though I would argue they might be better off in the long haul if they made a simply worded statement to this effect.)

But to think that somehow the world would be better off to give Boeing the death penalty over it, or abandon wholesale the present system for regulation and compliance certification over it, is just silly. What exactly would replace Boeing and the FAA? Something like the way Google, Tesla, Facebook develop and deploy product? I'll take Boeing and the FAA any day and 100 times on Saturday if that's the choice. These are all, at root, human systems. Human systems, at their best, will always occasionally fail. And, sadly, sometimes people will end up dead when they do. But the living learn, improve, and move on. When in human history has this not been how we have advanced?

(Full disclosure: I spent seven years of my long career working at a company partially owned by Boeing. I never worked in air transportation. I own investments in mutual funds that have, among other positions, positions in Boeing.)

This was very well said. The Seattle Times article is very bad, but we shouldn’t throw the baby out with the bath water and overreact.

Well, Douglas and McDonnell ceased to exist after some bad decisions. Since US would never allow foreign ownership, there are not too many options. How does "Lockheed 787" sound for you?
 
Backseater
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 1:56 am

The function is reset but not the stab trim. Everytime the stab trim is increased to push the nose down, isn’t the pilot going to have to increase the AoA to achieve his intended climb rate? In which case, MCAS is likely to exceed its current threshold even earlier than before?
I do hope that what I just wrote is erroneous and does not represent what the MCAS algorithm implements in practice!
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 2:05 am

Backseater wrote:
The function is reset but not the stab trim. Everytime the stab trim is increased to push the nose down, isn’t the pilot going to have to increase the AoA to achieve his intended climb rate? In which case, MCAS is likely to exceed its current threshold even earlier than before?
I do hope that what I just wrote is erroneous and does not represent what the MCAS algorithm implements in practice!

Correct. The stab does not go back to its original position without pilot input. Yes, if the pilot trims back to the high AoA position MCAS will make nose down inputs again. I'm not sure why you think this is a problem?
Phrogs Phorever
 
Elementalism
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 2:08 am

ciaran wrote:



What is the point of a dual input system is only one of the inputs is being used for MCAS to make a decision? Some seriously faulty design work imo. Especially on such a critical component of the flight system.
Honest question. Wouldn't it make more sense at this point to just have MCAS disabled until a fix can be verified to work?
 
Trin
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 2:10 am

flyingturtle wrote:
Wow, that piece by Dominic Gates is damning.

Nuke Boeing from orbit. It's the only way to be safe.

David


Yeah but they mostly come out at night.....

......Mostly.
 
weekendppl
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 2:17 am

kalvado wrote:
Well, Douglas and McDonnell ceased to exist after some bad decisions. Since US would never allow foreign ownership, there are not too many options. How does "Lockheed 787" sound for you?

Lockheed got to death's door over the L1011. Guaranteed: LockMart won't do commercial aviation again in our lifetime. The memory of the L1011 is way too fresh. (Not to mention numerous other "commercial" programs that lost boatloads of money. I kinda wonder how long Sikorsky will stay in the commercial helicopter business.
 
Backseater
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 2:28 am

dragon6172 wrote:
Backseater wrote:
The function is reset but not the stab trim. Everytime the stab trim is increased to push the nose down, isn’t the pilot going to have to increase the AoA to achieve his intended climb rate? In which case, MCAS is likely to exceed its current threshold even earlier than before?
I do hope that what I just wrote is erroneous and does not represent what the MCAS algorithm implements in practice!

Correct. The stab does not go back to its original position without pilot input. Yes, if the pilot trims back to the high AoA position MCAS will make nose down inputs again. I'm not sure why you think this is a problem?

I was under the impression (probably wrongfully so) that piloting with the stab trim in max nose down position would neither be easy nor advisable!
 
osiris30
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 2:30 am

Elementalism wrote:
ciaran wrote:



What is the point of a dual input system is only one of the inputs is being used for MCAS to make a decision? Some seriously faulty design work imo. Especially on such a critical component of the flight system.
Honest question. Wouldn't it make more sense at this point to just have MCAS disabled until a fix can be verified to work?


Apparently, the patch does just that. Uses multiple inputs now and has better alerting. (For what I gather in the press articles). The assumption here is the fault is with MCAS and NOT an upstream system like the AIDRU
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
RickNRoll
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 2:45 am

Self regulation is an oxymoron. Fund the FAA.

Sent from my Nokia 6.1 using Tapatalk
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 2:47 am

Backseater wrote:
I was under the impression (probably wrongfully so) that piloting with the stab trim in max nose down position would neither be easy nor advisable!

That is correct. But its not what we are talking about.
Phrogs Phorever
 
Backseater
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 3:01 am

Then I am totally confused. Please explain.
 
bolbibug
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 3:03 am

The most likely cause ET302 is similar to Lion Air is an issue with the AOA sensor. Barring that, the MCAS should not interfere with the flight controls.

If it is an AOA sensor issue, subsequent to the Lion Air incident, I would assume that:
1. 737 Max Pilots are very aware of the "runaway stabiliser" checklist items (STAB TRIM CUTOUT switch), to disable automatic stabiliser trimming, for the remainder of the flight.
2. 737 Max Pilots should be aware of the 737 Max behaviour with the automatic stabiliser trim systems switched off.

Assumption 2 is tricky. Between the Lion Air incident and now, how much time did 737-Max operators train, under the conditions with which ET302 was in, with the STAB TRIM CUTOUT switch in CUTOUT mode (assuming ET302 operators did the "runaway stabiliser" item).

----

I wonder how often sensor issues occur with modern airplanes. AF447 was initiated by a sensor issue, so was Lion Air, and possibly ET302.
Last edited by bolbibug on Mon Mar 18, 2019 3:20 am, edited 4 times in total.
 
RickNRoll
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 3:08 am

Elementalism wrote:
ciaran wrote:



What is the point of a dual input system is only one of the inputs is being used for MCAS to make a decision? Some seriously faulty design work imo. Especially on such a critical component of the flight system.
Honest question. Wouldn't it make more sense at this point to just have MCAS disabled until a fix can be verified to work?
I would love to know what testing was done for this software. Did they just do a " it's all ok if we test specifically for this" type of test?

Boeing is going to see a lot of legal action.

Sent from my Nokia 6.1 using Tapatalk
 
marcelh
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 3:09 am

AirlineCritic wrote:
I agree with others that the Seattle Times article is shocking.

Perhaps more than shocking. To begin with, even if the initial miss in the certification was perhaps a mistake, both FAA and Boeing knew *before* the ET crash that certification had missed a significant change, because Seattle Times told them. It seems to me that ET and the relatives of the passengers have a clear case against Boeing *and* FAA for, basically, wilful hiding of a significant failure in both the aircraft and the certification process. What other outcome should there have been even before the ET crash than to withdraw the certification temporarily and work to fix the system and/or redo the certification? But instead, they chose to sit on this information, and now 170 more people are dead.

I'd say the high standing of FAA in the world is now gone, and quite appropriately so. No sane regulator in the rest of the world should follow their advice.

And after the ET302 crash, both Boeing and the FAA were downplaying the grounding of the 737MAX by other authorities.
 
RickNRoll
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 3:15 am

bolbibug wrote:
The most likely cause ET302 is similar to Lion Air is an issue with the AOA sensor. Barring that, the MCAS should not interfere with the flight controls.

If it is an AOA sensor issue, subsequent to the Lion Air incident, I would assume that:
1. 737 Max Pilots are very aware of the "runaway stabiliser" checklist items (STAB TRIM CUTOUT switch), to disable automatic stabiliser trimming, for the remainder of the flight.
2. 737 Max Pilots should be aware (at least conceptually) of the 737 Max behaviour with the MCAS and other automatic stabiliser trimming systems switched off.

Assumption 2 is tricky. Between the Lion Air incident and now, how much time did 737-Max operators train, under the conditions with which ET302 was in, with the STAB TRIM CUTOUT switch in CUTOUT mode, and with the airplane in the condition ET302 was in.

----

I wonder how often sensor issues occur with modern airplanes. AF447 was initiated by a sensor issue, so was Lion Air, and possibly ET302.
Sensors will always fail and there should built in redundancy or a standard evidence/reaction procedure. AF447 experienced a known situation with a known, safe response. The plane itself was stable until it was made unstable. There was no requirement for instant action.

For MCAS the plane was made dangerously unstable with a evidence that was unclear. There was a requirement for instant action to avoid disaster.

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Aviation737
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 3:26 am

What I don't get is why didn't the other countries aviation authorities spot the problem also? Since it is their duty to certify whether the 737 MAX is safe to fly over their airspace. Did all of the aviation authorities miss out the MCAS issue?
 
hivue
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 3:29 am

dragon6172 wrote:
I'm not sure why you think this is a problem?


Hypothetical example: MCAS gets activated by a faulty AoA sensor. It trims down the max 2.5 deg. The pilot backs that out 2 degrees. Now 0.5 deg nose down trim. MCAS kicks in again with another 2.5. Now 3.0 deg nose down trim. The pilot backs out 1.5 deg. Now 2 deg nose down trim. You probably can see where this is leading.
Last edited by hivue on Mon Mar 18, 2019 3:34 am, edited 1 time in total.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
hivue
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 3:33 am

Elementalism wrote:
Honest question. Wouldn't it make more sense at this point to just have MCAS disabled until a fix can be verified to work?


Honest answer: It is disabled. The grounding has accomplished that.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
Planetalk
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 3:35 am

Numerous posters in this thread have made baseless insults towards pilots outside the US. Their clear insinuation being, we do it better here.

If that Seattle times article is true, and given the level of detail I suspect it is, this is. Goon to get very nasty for boeng, and probably the FAA. If I had stock in Boeing I might consider selling fast.

It's sickening. And they knew before this crash. And even after it gave us. BS about making a safer plane safer.

I grew up in awe of the jumbo, riding the 77W was one of my most exciting experiences. But this company is a disgrace. Don't defend them, it's clear they don't give a damn about any of us or our lives.
 
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Jouhou
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 3:41 am

Planetalk wrote:
Numerous posters in this thread have made baseless insults towards pilots outside the US. Their clear insinuation being, we do it better here.

If that Seattle times article is true, and given the level of detail I suspect it is, this is. Goon to get very nasty for boeng, and probably the FAA. If I had stock in Boeing I might consider selling fast.

It's sickening. And they knew before this crash. And even after it gave us. BS about making a safer plane safer.

I grew up in awe of the jumbo, riding the 77W was one of my most exciting experiences. But this company is a disgrace. Don't defend them, it's clear they don't give a damn about any of us or our lives.


I'll feel better if that douchewad ceo gets the axe and they start giving us clean sheet designs. They have the funds to do it. I'll cheer for Boeing again if they clean up their act. The 787 had a really tough entry and was a financial black hole for a long time but in the end it's turning out to be a really great aircraft that will be in production long enough for Boeing to make its money back. We need more of those.
情報
 
seat64k
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 3:42 am

remcor wrote:
Whoa, I havent heard this before, that Boeing sells the Max with an option package to have 3 AOA sensors and software to recognize disagreement. The two crash airplanes don’t have this option. Smells like mandatory retrofits may be coming

https://twitter.com/trevorsumner/status/1106934415610073091?s=21


Any way to know which airlines have this option, and which ones don't?
 
VS11
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 3:47 am

RickNRoll wrote:

Boeing is going to see a lot of legal action.

Sent from my Nokia 6.1 using Tapatalk


For the Lion Air crash, I don’t think the legal action is going to go far. Probably, it will end in out of court settlement. The rule of thumb is pilots follow manufacturers manuals and procedures, which is if you suspect problems with the trim, you disable it . That’s what the prior-flights pilots did. Boeing’s argument is solid in this case.

We don’t know what happened with the ET flight. It could be a different case or it could be that M.C.A.S. turned itself on during taxi or take-off roll or right after take off.
 
bolbibug
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 3:49 am

Planetalk wrote:
1. Numerous posters in this thread have made baseless insults towards pilots outside the US. Their clear insinuation being, we do it better here.
2. But this company is a disgrace. Don't defend them, it's clear they don't give a damn about any of us or our lives.


1. In some ways I believe countries that was involved in WW2 air-operations (and subsequent conflicts involving air operations) had more pilots with hands-on experience, and this experience trickles down into next generation commercial pilots as many military pilots switch over to commercial ops. Other countries will have to rely on simulators. In many cases, these smaller airlines don't even have simulators, they have to lease simulator time from another country. This doesn't take into account language issues and cultural issues governing Pilot and XO relations in the cockpit.

2. This is a hyperbole. A company will always try to find loopholes in the system to maximize profit. It is the job of government to govern them and limit the power of corporations in influencing policy. The USA does a very bad job at governing and keeping mega corporations and their lobbies in check. Boeing is not the only party to blame.

My kids would be on their ipads all day long if they could. Do they give a damn about what excess exposure could do? No. Are they a disgrace? No. It's my job to lay down the rules and make sure they follow. If I let them certify and control their own ipad schedules, I would be a bad parent, the blame would not be on them.
Last edited by bolbibug on Mon Mar 18, 2019 4:12 am, edited 5 times in total.
 
N47
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 3:51 am

Partly delegating inspections to a private entity and this happened. Imagine what would happen if they fully privatized the FAA.
 
RickNRoll
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 4:11 am

VS11 wrote:
RickNRoll wrote:

Boeing is going to see a lot of legal action.

Sent from my Nokia 6.1 using Tapatalk


For the Lion Air crash, I don’t think the legal action is going to go far. Probably, it will end in out of court settlement. The rule of thumb is pilots follow manufacturers manuals and procedures, which is if you suspect problems with the trim, you disable it . That’s what the prior-flights pilots did. Boeing’s argument is solid in this case.

We don’t know what happened with the ET flight. It could be a different case or it could be that M.C.A.S. turned itself on during taxi or take-off roll or right after take off.
According to that article, the MCAS was not a trained trim problem, which was continuous trimming. That threw the pilots off. MCAS was not documented. MCAS was not tested properly.

Sent from my Nokia 6.1 using Tapatalk
 
rnav2dlrey
Posts: 382
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 4:12 am

WSJ is now reporting that a DOJ criminal investigation is in its initial stages. Subpoena(s) have been issued by a federal grand jury, at the very least in an attempt to preserve documents.

this probably warrants its own thread.

excerpt:

The Justice Department probe involves a prosecutor in the fraud section of the department’s criminal division, a unit that has brought cases against well-known manufacturers over safety issues, including Takata Corp.

In the U.S., it is highly unusual for federal prosecutors to investigate details of regulatory approval of commercial aircraft designs, or to use a criminal probe to delve into dealings between the FAA and the largest aircraft manufacturer the agency oversees. Probes of airliner programs or alleged lapses in federal safety oversight typically are handled as civil cases, often by the DOT inspector general. The inspector general, however, does have authority to make criminal referrals to federal prosecutors and has its own special agents.



(paywall): https://www.wsj.com/articles/faas-737-m ... 1552868400
 
zoom321
Posts: 46
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 4:20 am

RickNRoll wrote:
Elementalism wrote:
ciaran wrote:



What is the point of a dual input system is only one of the inputs is being used for MCAS to make a decision? Some seriously faulty design work imo. Especially on such a critical component of the flight system.
Honest question. Wouldn't it make more sense at this point to just have MCAS disabled until a fix can be verified to work?
I would love to know what testing was done for this software. Did they just do a " it's all ok if we test specifically for this" type of test?

Boeing is going to see a lot of legal action.

Sent from my Nokia 6.1 using Tapatalk

There you go,

https://www.seattletimes.com/business/b ... air-crash/

"..............There is no evidence that Boeing did flight-testing of MCAS with erroneous sensor data, and it is not clear whether the FAA did so. European regulators flight-tested the new version of the plane with normal sensor data feeding into MCAS but not with bad data, the pilot familiar with the European certification process said. ........................"
 
VS11
Posts: 1661
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Mar 18, 2019 4:23 am

RickNRoll wrote:
VS11 wrote:
RickNRoll wrote:

Boeing is going to see a lot of legal action.

Sent from my Nokia 6.1 using Tapatalk


For the Lion Air crash, I don’t think the legal action is going to go far. Probably, it will end in out of court settlement. The rule of thumb is pilots follow manufacturers manuals and procedures, which is if you suspect problems with the trim, you disable it . That’s what the prior-flights pilots did. Boeing’s argument is solid in this case.

We don’t know what happened with the ET flight. It could be a different case or it could be that M.C.A.S. turned itself on during taxi or take-off roll or right after take off.
According to that article, the MCAS was not a trained trim problem, which was continuous trimming. That threw the pilots off. MCAS was not documented. MCAS was not tested properly.

Sent from my Nokia 6.1 using Tapatalk


But if two crews from the same company, presented with the same problem on the same aircraft in sequential flights had different response and outcomes then it is the crew actions at the core of it because everything else was the same. M.C.A.S. could have been perfectly designed and there could still happen an emergency involving trim. You have to apply emergency procedures even if you have perfectly designed systems.

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