StTim
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 4:55 pm

Apparently the pinger was still issuing weak pings. May have helped when they got close.
 
N212R
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 4:57 pm

FlyXLsa wrote:
That they succeeded where the MPV Everest failed with superior technology makes this a good day for the Indonesian Navy.


Given the little we know of the actual recovery, how would you explain the success of the Navy where a "superior" team had previously and for a longer duration failed?

Excellent and informative post Sheik. Great pix gives a whole new meaning to Dump-ster diving!
 
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neutrino
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 5:01 pm

FlyXLsa wrote:
I saw a picture of the CVR on twitter with the Pinger sitting next to it so I'm not sure if the Everest Crew was instrumental in narrowing the search area or not? I didn't mean to downplay their contribution to the search effort. It would be nice if Lion Air got SOMETHING for the $2.5+ Million they paid out!

And I didn't mean to cast any pall on your phrase that I bolded. Just that it struck me as how can the Navy be so plain lucky to correctly zero in on such a small work area and get a fast result without outside input. Maybe they really have their own deep resources. Whichever way it went, kudos to all involved in the CVR recovery.
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FlyXLsa
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 5:11 pm

jetmatt777 wrote:
Exactly! Aviate. Navigate. Communicate. Keep the damn thing in the air before you start turning. I feel terrible for the crew who the cards were stacked against them. It’s easy to say from the ground what should have been done differently. Let’s let the investigation conclude before we all hang the pilots. They’ve died once already, let’s see what the experts have to say.


Unfortunately in a high profile accident with many lives lost, a pilots actions or lack thereof are going to be subject to intense scrutiny by the press, the investigative process and aviation forums like this. That is one of the occupational hazards of the job. Whether it is this accident, MH370, QZ8501, US1549 or one of the many other recent accidents, we learn from this process so hopefully we don't end up in a similar situation. We know the cause of the accident was MCAS pushing the nose down to the point the crew lost control. We have a fairly good idea of the action the crew did not take from the published EAD, Boeing statement (unusual in an ongoing investigation) and the KNKT Preliminary Report - i.e. failure to action the cutout switches for the Stab Trim. The CVR will add to our understanding of why this was not done, but in the meantime we're still going to discuss this accident. Boeing, Lion Air, Maintenance, the applicable Regulatory Bodies and the Pilots are under the microscope of this and other forums. We owe this crew respect as fellow aviators, but not our silence in the matter at hand.
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FlyXLsa
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 5:20 pm

N212R wrote:
Given the little we know of the actual recovery, how would you explain the success of the Navy where a "superior" team had previously and for a longer duration failed?


I was basing my opinion on statements made by the KNKT/Navy that they had a ping detector and some other equipment. The "paid guns" may well have done a good job too - I don't know? I'm just happy for the Indonesian Navy Divers. They lost one of their own in the prior search and this is a bright spot for them in an otherwise dismal situation for the entire country. R.I.P. all.
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FTMCPIUS
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 5:27 pm

Considering the negligible cost of a adding a few extra watts power output (and more bigger battery) when compared to the extended recovery costs these past few months, why don't they do this? I suppose the answer is there aren't enough crashes with these circumstances to justify the extra cost and weight. Unfortunate in that it's possible the CVR search may have soon been called off for good if not found when it was.
 
hivue
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 5:42 pm

FlyXLsa wrote:
We have a fairly good idea of the action the crew did not take from the published EAD, Boeing statement (unusual in an ongoing investigation) and the KNKT Preliminary Report - i.e. failure to action the cutout switches for the Stab Trim.


But Boeing made this statement following the preliminary report --

"Boeing released a statement in response to publication of the NTSC preliminary report in which it makes this observation: 'Unlike as is stated with respect to the prior flight, the report does not state whether the pilots performed the runaway stabilizer procedure or cut out the stabilizer trim switches.'"

Source: https://www.aerosociety.com/news/lion-air-lessons/
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
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FlyXLsa
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 6:01 pm

hivue wrote:
FlyXLsa wrote:
We have a fairly good idea of the action the crew did not take from the published EAD, Boeing statement (unusual in an ongoing investigation) and the KNKT Preliminary Report - i.e. failure to action the cutout switches for the Stab Trim.


But Boeing made this statement following the preliminary report --

"Boeing released a statement in response to publication of the NTSC preliminary report in which it makes this observation: 'Unlike as is stated with respect to the prior flight, the report does not state whether the pilots performed the runaway stabilizer procedure or cut out the stabilizer trim switches.'"

Source: https://www.aerosociety.com/news/lion-air-lessons/


Read "between" the lines. Boeing stopped short of that particular statement, but did say:

"The report states that the flight crew of the Oct. 28 flight turned off the stabilizer trim switches within minutes of experiencing the automatic nose down trim, and continued with manual trim through the end of the flight. The report further notes that the pilot performed three non-normal checklist procedures, including the runaway stabilizer non-normal checklist, which is a memory item prescribed by the 737 MAX Flight Crew Operations Manual, and reaffirmed in Boeing Flight Crew Operations Manual Bulletin TBC-19 and FAA Emergency Airworthiness Directive (AD) Number 2018-23-51, as the appropriate procedure to address unintended horizontal stabilizer movement, regardless of source."

https://boeing.mediaroom.com/news-relea ... tem=130336

Edit:
Why do you think Rusdi Kirana threw a media temper tantrum about cancelling the Boeing order?
HE accused Boeing of throwing Lion Air and it's pilots/mx under the bus.
In addition the FDR chart shows power to the system through the nose dive.
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hivue
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 6:39 pm

FlyXLsa wrote:
Boeing stopped short of that particular statement


No, as a matter of fact that statement is in your link if you read far enough. I just find it interesting that Boeing felt the need to point out the fact.

I take your point that the evidence at hand so far suggests the crew did not run the runaway stab trim procedure. But, actually, did they or didn't they? Did they fail to run it completely? Did they run it but for some weird reason it didn't work? Did they run it but get distracted and not complete it? Did they run it but events overwhelmed them before they could complete it?

I'm in the camp that says don't condemn he crew before all the available facts are in. With the CVR now recovered we hopefully will soon have answers to these questions.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
ikramerica
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 7:00 pm

FlyXLsa wrote:
hivue wrote:
FlyXLsa wrote:
We have a fairly good idea of the action the crew did not take from the published EAD, Boeing statement (unusual in an ongoing investigation) and the KNKT Preliminary Report - i.e. failure to action the cutout switches for the Stab Trim.


But Boeing made this statement following the preliminary report --

"Boeing released a statement in response to publication of the NTSC preliminary report in which it makes this observation: 'Unlike as is stated with respect to the prior flight, the report does not state whether the pilots performed the runaway stabilizer procedure or cut out the stabilizer trim switches.'"

Source: https://www.aerosociety.com/news/lion-air-lessons/


Read "between" the lines. Boeing stopped short of that particular statement, but did say:

"The report states that the flight crew of the Oct. 28 flight turned off the stabilizer trim switches within minutes of experiencing the automatic nose down trim, and continued with manual trim through the end of the flight. The report further notes that the pilot performed three non-normal checklist procedures, including the runaway stabilizer non-normal checklist, which is a memory item prescribed by the 737 MAX Flight Crew Operations Manual, and reaffirmed in Boeing Flight Crew Operations Manual Bulletin TBC-19 and FAA Emergency Airworthiness Directive (AD) Number 2018-23-51, as the appropriate procedure to address unintended horizontal stabilizer movement, regardless of source."

https://boeing.mediaroom.com/news-relea ... tem=130336

Edit:
Why do you think Rusdi Kirana threw a media temper tantrum about cancelling the Boeing order?
HE accused Boeing of throwing Lion Air and it's pilots/mx under the bus.
In addition the FDR chart shows power to the system through the nose dive.

The Boeing statement clearly indicates Boeing’s position. “Regardless of source”. Their main point will be, and rightfully so to at least some degree, that it’s not important for the pilot to know the specific reason for runaway trim when trying to stop it. There is a non-normal checklist that says turn it off. It’s in the MAX training, it’s in the NG training, it’s in the training for many (all?) aircraft.

Boeing is claiming that on the fateful flight, the pilots did not follow the non-normal checklist procedure despite having many minutes to do so. Further, it seams as if they initiated a turn without doing the checklist, which looks to have led to an immediate nosedive and crash. That’s a failure in airmanship.
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LDRA
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 7:05 pm

Does running Boeing 737 Runaway Stab NNC procedure ALWAYS lead to cut out switch? Can someone post the page from QRH
 
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FlyXLsa
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 7:06 pm

hivue wrote:
No, as a matter of fact that statement is in your link if you read far enough. I just find it interesting that Boeing felt the need to point out the fact.

I take your point that the evidence at hand so far suggests the crew did not run the runaway stab trim procedure. But, actually, did they or didn't they? Did they fail to run it completely? Did they run it but for some weird reason it didn't work? Did they run it but get distracted and not complete it? Did they run it but events overwhelmed them before they could complete it?


The last line of the Boeing statement reads as follows:
"Unlike as is stated with respect to the prior flight (JT43), the report does not state whether the pilots (of JT610) performed the runaway stabilizer procedure or cut out the stabilizer trim switches."

The two cutouts worked for the JT43 crew so it is highly unlikely that suddenly they would somehow become inoperable for the JT610 flight/crew? It's not impossible, but highly improbable that a simple breakout circuit switch would fail if that is what you are suggesting.

Edit: Sorry that was in response to a hypothesis by "hivue" a few posts up.

A copy of a 737NG QRH can be viewed here: http://www.737ng.co.uk/737-800%20Quick% ... QRH%29.pdf
Last edited by FlyXLsa on Tue Jan 15, 2019 7:35 pm, edited 1 time in total.
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fadecfault
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 7:29 pm

hivue wrote:
FlyXLsa wrote:
Boeing stopped short of that particular statement


No, as a matter of fact that statement is in your link if you read far enough. I just find it interesting that Boeing felt the need to point out the fact.

I take your point that the evidence at hand so far suggests the crew did not run the runaway stab trim procedure. But, actually, did they or didn't they? Did they fail to run it completely? Did they run it but for some weird reason it didn't work? Did they run it but get distracted and not complete it? Did they run it but events overwhelmed them before they could complete it?

I'm in the camp that says don't condemn he crew before all the available facts are in. With the CVR now recovered we hopefully will soon have answers to these questions.


They did not cut out as manual trim would have never worked. They manually trimmed at least 26 times but failed to keep up with it at the end and allowed the stab to trim by itself all the way to zero.
The previous flight crew did the cut out and used the trim wheel to trim nose up towards the approach.
All of this is shown in the reports. The cvr will make it clear why they stopped trimming at the end.
The views and opinions written here are my own and do not reflect those of my employer.
 
salttee
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 8:11 pm

FlyXLsa wrote:
The two cutouts worked for the JT43 crew so it is highly unlikely that suddenly they would somehow become inoperable for the JT610 flight/crew? It's not impossible, but highly improbable that a simple breakout circuit switch would fail if that is what you are suggesting.

This is where I get lost in these discussions. If I missed something I apologize, but is there indication that the earlier flight also experienced stab trim runaway as did the fatal flight? My understanding was that the earlier flight had experienced a loss of airspeed and altitude information only. Where is the source of information saying that they activated the stab trim cutout switches on the console?
 
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FlyXLsa
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 8:25 pm

salttee wrote:
This is where I get lost in these discussions. If I missed something I apologize, but is there indication that the earlier flight also experienced stab trim runaway as did the fatal flight? My understanding was that the earlier flight had experienced a loss of airspeed and altitude information only. Where is the source of information saying that they activated the stab trim cutout switches on the console?


The ran three NNC's and flipped the switches as per the R/W Stab NNC. It's in the KNKT Report and is summarized in the latter part of the Boeing Statement here:

On Oct. 28, before the flight immediately prior to Flight 610, the pilot in command and the maintenance engineer discussed the maintenance that had been performed on the aircraft. The engineer informed the pilot that the AOA sensor had been replaced and tested. The report does not include records as to the installation or calibration of the new sensor, nor does the report indicate whether the sensor was new or refurbished. Although the report states that the pilot was satisfied by the information relayed by the engineer that the AOA sensor had been replaced and tested, on the subsequent flight the pilots again experienced problems with erroneous airspeed data, and also experienced automatic nose down trim.

The report states that the flight crew of the Oct. 28 flight turned off the stabilizer trim switches within minutes of experiencing the automatic nose down trim, and continued with manual* trim through the end of the flight. The report further notes that the pilot performed three non-normal checklist procedures, including the runaway stabilizer non-normal checklist, which is a memory item prescribed by the 737 MAX Flight Crew Operations Manual, and reaffirmed in Boeing Flight Crew Operations Manual Bulletin TBC-19 and FAA Emergency Airworthiness Directive (AD) Number 2018-23-51, as the appropriate procedure to address unintended horizontal stabilizer movement, regardless of source.


*Manual as in turning the trim wheel by hand
https://boeing.mediaroom.com/news-relea ... tem=130336
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hivue
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 8:26 pm

salttee wrote:
but is there indication that the earlier flight also experienced stab trim runaway as did the fatal flight?


Yes, they did. They did the runaway stab trim procedure and continued to destination trimming with the trim wheel.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
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trpmb6
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 8:28 pm

salttee wrote:
FlyXLsa wrote:
The two cutouts worked for the JT43 crew so it is highly unlikely that suddenly they would somehow become inoperable for the JT610 flight/crew? It's not impossible, but highly improbable that a simple breakout circuit switch would fail if that is what you are suggesting.

This is where I get lost in these discussions. If I missed something I apologize, but is there indication that the earlier flight also experienced stab trim runaway as did the fatal flight? My understanding was that the earlier flight had experienced a loss of airspeed and altitude information only. Where is the source of information saying that they activated the stab trim cutout switches on the console?


From the official report: https://knkt.dephub.go.id/knkt/ntsc_avi ... Report.pdf

Pages 19 and 20 address the previous flight, quite thoroughly. On page 20:

The PIC handed over control to the SIC and announced “memory item airspeed
unreliable”.
After the transfer of control, the PIC cross checked the PFDs with the
standby instrument and determined that the left PFD had the problem. The PIC then
switched on the right flight director (FD) so the SIC would have a normal display.
While handling the problem, the PIC instructed the SIC to continue acceleration and
flap retraction as normal. The PIC commanded the SIC to follow FD command and
re-trim the aircraft as required. The PIC noticed that as soon the SIC stopped trim
input, the aircraft was automatically trimming aircraft nose down (AND).

After three automatic AND trim occurrences, the SIC commented that the control
column was too heavy to hold back. At 14:25:46 UTC, the PIC declared “PAN
PAN” to the Denpasar Approach controller due to instrument failure and requested to
maintain runway heading. The Denpasar Approach controller acknowledged the
message and approved the pilot request. A few second later, the Denpasar Approach
controller asked the LNI043 whether he wanted to return to Denpasar and the pilot
responded “standby”.

At 14:28:28 UTC, the PIC moved the STAB TRIM switches to CUT OUT. The PIC
re-engaged the STAB TRIM switches to NORMAL, but almost immediately the
problem re-appeared. The PIC then moved the STAB TRIM switches back to CUT
OUT and continued with manual trim without auto-pilot until the end of the flight


As I've consistently stated in this thread's last 59 pages, this is 100% a memory item. It does not matter what was causing the unreliable airspeed indication and the nose down runaway trim. All that matters is that this is a memory item and should be addressed with the standard procedures. Speaking from an engineering perspective, I could see why there would be no need to update operating manuals to address the MCAS having the possibility to produce this, when the solution is already addressed.
Last edited by trpmb6 on Tue Jan 15, 2019 8:32 pm, edited 1 time in total.
 
salttee
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 8:37 pm

OMG I had missed that.

Thanks for restating it.
 
StTim
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 9:36 pm

I quote from the linked QRH.

"Uncommanded stabilizer trim movement
occurs continuously"

In this case the stabilizer movement was not continuous but in stepped stages as per the MCAS design. Hence this QRH was not obviously applicable.
 
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trpmb6
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 9:40 pm

StTim wrote:
I quote from the linked QRH.

"Uncommanded stabilizer trim movement
occurs continuously"

In this case the stabilizer movement was not continuous but in stepped stages as per the MCAS design. Hence this QRH was not obviously applicable.


In what way was it stepped? Because they re-engaged flaps?
 
hivue
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 10:06 pm

trpmb6 wrote:
In what way was it stepped? Because they re-engaged flaps?


Every time they manually trimmed, MCAS got out of the way. When they got the airplane in trim and stopped manually trimming, MCAS would jump back in and trim the nose down.

It's kind of hair-splitting, I would think, to say that this behavior means it didn't meet the requirements for the QRH procedure.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
StTim
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 10:09 pm

The description of the way MCAS functions is that it applies trim in steps and NOT continuously.

Here is https://theaircurrent.com/aviation-safe ... cas-jt610/ what I read.
 
fadecfault
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 10:11 pm

trpmb6 wrote:
StTim wrote:
I quote from the linked QRH.

"Uncommanded stabilizer trim movement
occurs continuously"

In this case the stabilizer movement was not continuous but in stepped stages as per the MCAS design. Hence this QRH was not obviously applicable.


In what way was it stepped? Because they re-engaged flaps?


He's trying to argue that because mcas moves in increments rather than a single continual application that it would not be considered a runway trim situation.
He neglects to look at the FDR graphs showing that on take off the aircraft trimmed nose down continuously resulting massive loss of altitude.
This is on takeoff and it was continual. Obviously this is not normal behavior and should have resulted in the pilots hitting the switches.
But he wants to argue that steps ≠ continual.
The views and opinions written here are my own and do not reflect those of my employer.
 
StTim
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 10:18 pm

Ok - I looked up the dictionary meaning of continuously and it was "without interruption or gaps"

Hence a process that is repeatedly applied in steps is not continuously from a pure English perspective. Now it may be that the QRH that was linked above did not mean it in that way - but that would be inaccurate use of the language and open to misinterpretation.
 
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trpmb6
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 10:23 pm

Definitely hair splitting as far as I'm concerned.

An uncommanded trim operation that is happening on a repeat interval is to be considered "continuous" as far as I'm concerned.
 
hivue
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 10:55 pm

trpmb6 wrote:
An uncommanded trim operation


It wasn't "uncommanded." MCAS was doing the commanding. On modern airliners there is a whole lot of commanding being done by the autoflight systems.

But, still, this probably would be hair splitting regarding whether the runaway stab trim procedure was appropriate or not. (But, then, maybe the accident crew were hair splitters. We should find out from the CVR.)
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
LDRA
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 11:03 pm

hivue wrote:
trpmb6 wrote:
In what way was it stepped? Because they re-engaged flaps?


Every time they manually trimmed, MCAS got out of the way. When they got the airplane in trim and stopped manually trimming, MCAS would jump back in and trim the nose down.

It's kind of hair-splitting, I would think, to say that this behavior means it didn't meet the requirements for the QRH procedure.


After manual electrical trim input, MCAS would wait 5 seconds before re-activate.

So after manual electrical trim input, the trim wheel simply does not move for 5 seconds. This pattern is extremely similar to normal STS behavior, where STS would stop trimming for 10 seconds after manual electrical trim input.

The word "Continuously" in NNC is actually critical identification criteria for the NNC. because otherwise, one can easily mistaken STS trim input for erroneous trim system activation. Note that there is no indication to flight crew STS or other automatic trim input(mach trim) activation. So there is no way to reliably identify "Uncommanded Trim". One can only identify "Continuously"
Last edited by LDRA on Tue Jan 15, 2019 11:11 pm, edited 1 time in total.
 
LDRA
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 11:11 pm

If you look at the FAA AD

In the event an uncommanded nose down stabilizer trim is experienced
on the 737-8/-9, in conjunction with one or more of the indications or
effects listed below...


It is the same the reason "in conjunction with one or more of the indications or effects listed below" criterion is needed together with "uncommanded" to IDENTIFY MCAS failure due to AoA.
 
fadecfault
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 11:16 pm

LDRA wrote:
hivue wrote:
trpmb6 wrote:
In what way was it stepped? Because they re-engaged flaps?


Every time they manually trimmed, MCAS got out of the way. When they got the airplane in trim and stopped manually trimming, MCAS would jump back in and trim the nose down.

It's kind of hair-splitting, I would think, to say that this behavior means it didn't meet the requirements for the QRH procedure.


After manual electrical trim input, MCAS would wait 5 seconds before re-activate.

So after manual electrical trim input, the trim wheel simply does not move for 5 seconds. This pattern is extremely similar to normal STS behavior, where STS would stop trimming for 10 seconds after manual electrical trim input.

The word "Continuously" in NNC is actually critical identification criteria for the NNC. because otherwise, one can easily mistaken STS trim input for erroneous trim system activation. Note that there is no indication to flight crew STS or other automatic trim input(mach trim) activation. So there is no way to reliably identify "Uncommanded Trim". One can only identify "Continuously"


So continual ND trim forcing the aircraft to dive on take off at speeds in which speed trim does not operate is normal? Have you bothered to look at the FDR data?
The views and opinions written here are my own and do not reflect those of my employer.
 
asdf
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 11:40 pm

trpmb6 wrote:
Definitely hair splitting as far as I'm concerned.

An uncommanded trim operation that is happening on a repeat interval is to be considered "continuous" as far as I'm concerned.


there are a lot of trimm operations from flightcontrols all the time

they start
and they stop
and then they start again

how would those guys know that the trim opration they experienced are NOT one oft the usual ones?

if they would have been continuose ones ... non reversible and non stoppable ... ok ... this is a runaway
but those stopped by design every five seconds .... and the crew didnt had a clue why bevause noone told them about MCAS
 
LDRA
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Tue Jan 15, 2019 11:52 pm

fadecfault wrote:
LDRA wrote:
hivue wrote:

Every time they manually trimmed, MCAS got out of the way. When they got the airplane in trim and stopped manually trimming, MCAS would jump back in and trim the nose down.

It's kind of hair-splitting, I would think, to say that this behavior means it didn't meet the requirements for the QRH procedure.


After manual electrical trim input, MCAS would wait 5 seconds before re-activate.

So after manual electrical trim input, the trim wheel simply does not move for 5 seconds. This pattern is extremely similar to normal STS behavior, where STS would stop trimming for 10 seconds after manual electrical trim input.

The word "Continuously" in NNC is actually critical identification criteria for the NNC. because otherwise, one can easily mistaken STS trim input for erroneous trim system activation. Note that there is no indication to flight crew STS or other automatic trim input(mach trim) activation. So there is no way to reliably identify "Uncommanded Trim". One can only identify "Continuously"


So continual ND trim forcing the aircraft to dive on take off at speeds in which speed trim does not operate is normal? Have you bothered to look at the FDR data?


Is speed trim operating speed range a memory item?
 
PJ01
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 12:06 am

asdf wrote:
trpmb6 wrote:
Definitely hair splitting as far as I'm concerned.

An uncommanded trim operation that is happening on a repeat interval is to be considered "continuous" as far as I'm concerned.


there are a lot of trimm operations from flightcontrols all the time

they start
and they stop
and then they start again

how would those guys know that the trim opration they experienced are NOT one oft the usual ones?


Because the trim operations that the aircraft was performing meant the aircraft was trying to nosedive maybe?
The fact that the crew kept correcting the incorrect trim would indicate they knew the auto trim inputs were not normal.
 
LDRA
Posts: 197
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 12:15 am

PJ01 wrote:
asdf wrote:
trpmb6 wrote:
Definitely hair splitting as far as I'm concerned.

An uncommanded trim operation that is happening on a repeat interval is to be considered "continuous" as far as I'm concerned.


there are a lot of trimm operations from flightcontrols all the time

they start
and they stop
and then they start again

how would those guys know that the trim opration they experienced are NOT one oft the usual ones?


Because the trim operations that the aircraft was performing meant the aircraft was trying to nosedive maybe?
The fact that the crew kept correcting the incorrect trim would indicate they knew the auto trim inputs were not normal.


Issue with that is STS is not auto-trim, it is not an workload relief feature designed to help keep aircraft trimmed to speed. In fact, the purpose of STS is exactly opposite. STS is designed to put aircraft MORE out of trim as aircraft speed changes. Typically, flight crew just use manual electrical trim to stop STS trim operation, which the Lion air flight crew also did

STS is required due to FAR25.173. 737 natural longitude control characteristics does not meet 1 pound for each 6 knots gradient, so STS is needed to augment control column feeling to meet that
 
RogerMurdock
Posts: 149
Joined: Sat Aug 23, 2014 9:01 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 12:49 am

In our discussion, many times people refer to 'runaway trim'. One issue is that our understanding of what 'runaway trim' includes the knowledge of what happened on this flight. Indeed, the broader aviation community may have a new standard and viewpoint for 'runaway trim' based on this incident.

It may very well be that the pilots on the incident flight saw the intermittent/non-continuous behavior and it did not fit their mental model of what 'runaway trim' truly is. The behavior may have more resembled systems they were familiar with, such as STS, albeit manufacturing in a strange manner in a strange phase of flight.* So they failed to move to that NNC.

*The previous crew diagnosed the problem as "STS operating in reverse". However, to them it conformed to their mental model of runaway trim and they did the cutout.
 
salttee
Posts: 3149
Joined: Wed Jul 13, 2016 3:26 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 1:18 am

Do pilots learn systems from the inside out or the outside in?

The answer should be obvious; first they learn what an elevator does, then they learn about elevator trim, then later they learn about automatic systems that can initiate elevator trim.
 
User avatar
FlyXLsa
Posts: 59
Joined: Thu Dec 27, 2018 5:03 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 1:31 am

salttee wrote:
Do pilots learn systems from the inside out or the outside in?

The answer should be obvious; first they learn what an elevator does, then they learn about elevator trim, then later they learn about automatic systems that can initiate elevator trim.


The Trim system on a 737 is a little different that that of a Cessna 150. You actually trim with Horizontal Stabilizer by moving it.
There really isn't Elevator Trim per se on the 737 like a Cessna. You move Stabilizer up and down to accomplish the same task.
So basically yes to your first question re inside/out... this is a basic flight control system that every big jet pilot is trained on.
Whiskey-Oscar-Oscar-Foxtrot
 
salttee
Posts: 3149
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 2:42 am

FlyXLsa wrote:
The Trim system on a 737 is a little different that that of a Cessna 150...........

Yes, a 150 (or a Citabria like I learned on) has just a trim tab, the same as Cessna twins and the Citations. But functionally these are the same as a 737s' moving horizontal stabilizer. The 737 also has has power assisted trim as airtechy described in post #2566; which brought about the need for the stat trim override switches. All aircraft with any kind of power assisted elevator trim require stat trim override switches. They are not unique to the 737.

A pilot learns about elevator trim in his first trainer and progresses to a plane with powered trim at some point in his training and from there on he has to be aware of stat trim override switches. If a plane he later qualifies on has a flight director or an autopilot, he then learns that automatic trim can also come into play. But the base of his knowledge of elevator trim already exists before he gets to such an advanced aircraft.

That's what I meant when I said a pilot learns from the outside in.
 
Chemist
Posts: 500
Joined: Tue Oct 20, 2015 4:46 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 4:00 am

I am flying and the plane is getting hard to control, it wants to go nose down, the trim wheel keeps clicking intermittently, trimming down until I have trouble controlling, I'm not going to think "Nope, it's not continuous without a break, so even though I can't control this nose down trim I won't hit the trim disconnect switches, because I'd rather lose control as somehow this isn't continuous enough".
 
LDRA
Posts: 197
Joined: Fri Jan 15, 2016 3:01 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 4:19 am

Chemist wrote:
I am flying and the plane is getting hard to control, it wants to go nose down, the trim wheel keeps clicking intermittently, trimming down until I have trouble controlling, I'm not going to think "Nope, it's not continuous without a break, so even though I can't control this nose down trim I won't hit the trim disconnect switches, because I'd rather lose control as somehow this isn't continuous enough".


Will they hear trim wheel clicking while stall warning vibrating the control column loudly?

The same failed AoA signal that causes false stall warning is also causing air speed disagree, altitude disagree among other cockpit warning indications. Are they going to prioritize resolving a "STS work in reverse" problem, or are they going to just trim away the unwanted "STS trim input" like they do normally anyways and work other problems that are more glaring

CVR should tell us
 
Chemist
Posts: 500
Joined: Tue Oct 20, 2015 4:46 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 4:23 am

LDRA wrote:
Chemist wrote:
I am flying and the plane is getting hard to control, it wants to go nose down, the trim wheel keeps clicking intermittently, trimming down until I have trouble controlling, I'm not going to think "Nope, it's not continuous without a break, so even though I can't control this nose down trim I won't hit the trim disconnect switches, because I'd rather lose control as somehow this isn't continuous enough".


Will they hear trim wheel clicking while stall warning vibrating the control column loudly?

The same failed AoA signal that causes false stall warning is also causing air speed disagree, altitude disagree among other cockpit warning indications. Are they going to prioritize resolving a "STS work in reverse" problem, or are they going to just trim away the unwanted "STS trim input" like they do normally anyways and work other problems that are more glaring

CVR should tell us


If I can't hold enough back pressure to control the plane, I'm disconnecting the electric trim. I'm not going to nitpick whether the "runaway trim" is continuous or not.
 
BlackCat
Posts: 7
Joined: Tue Jan 15, 2019 8:18 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 5:47 am

Hi all.. I saw a local tv news in jkt. The reporter ask one of indonesian ?navy diving team about the vcr findings.. They said that they found the vcr just 28 Centimeters bellow the mud.. Not 28 feed ! But still.. It was very difficult task.. Sory for my english..
 
rheinwaldner
Posts: 1674
Joined: Wed Jan 02, 2008 4:58 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 9:33 am

fadecfault wrote:
He's trying to argue that because mcas moves in increments rather than a single continual application that it would not be considered a runway trim situation.

No, the argument is not the incremental activation but the fact, that it stopped immediately by applying manual trim on the yoke.

--> Stopped automatic trim ≠ trim runaway.
Many things are difficult, all things are possible!
 
pugman211
Posts: 461
Joined: Thu Dec 20, 2012 1:55 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 10:02 am

Can you class the incident as a runaway stabiliser though really? I mean, it was a programmed input from MCAS. The fact that MCAS didn't know it was being fed erronus data is irrelevant to the programme, it was carrying out the programmed algorithm, or am I misunderstanding it?

One thing that I do agree on with people, is that the crew should of used the cut outs, but it's clear to see the were either overwhelmed with what was happening or misunderstood the situation.

Hopefully the CVR will explain the thoughts process.
 
blrsea
Posts: 1879
Joined: Fri May 20, 2005 2:22 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 10:10 am

How long do they typically take to analyze the CVR, and release it into public domain? Do they usually release the full cockpit conversations transcript relating to the incident ? Or just brief summary?
 
fadecfault
Posts: 164
Joined: Mon Nov 05, 2007 8:44 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 11:41 am

LDRA wrote:
PJ01 wrote:
asdf wrote:

there are a lot of trimm operations from flightcontrols all the time

they start
and they stop
and then they start again

how would those guys know that the trim opration they experienced are NOT one oft the usual ones?


Because the trim operations that the aircraft was performing meant the aircraft was trying to nosedive maybe?
The fact that the crew kept correcting the incorrect trim would indicate they knew the auto trim inputs were not normal.


Issue with that is STS is not auto-trim, it is not an workload relief feature designed to help keep aircraft trimmed to speed. In fact, the purpose of STS is exactly opposite. STS is designed to put aircraft MORE out of trim as aircraft speed changes. Typically, flight crew just use manual electrical trim to stop STS trim operation, which the Lion air flight crew also did

STS is required due to FAR25.173. 737 natural longitude control characteristics does not meet 1 pound for each 6 knots gradient, so STS is needed to augment control column feeling to meet that


Speed trim is taught during gen fam class and it is known as low speed trim. The purpose of speed trim is to oppose airspeed changes : ie as the airspeed increases the aircraft will trim UP.
What manual says the flight crew will use manual electric trim to stop speed trim?
The views and opinions written here are my own and do not reflect those of my employer.
 
fsabo
Posts: 197
Joined: Fri Dec 04, 2015 8:41 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 11:52 am

BlackCat wrote:
Hi all.. I saw a local tv news in jkt. The reporter ask one of indonesian ?navy diving team about the vcr findings.. They said that they found the vcr just 28 Centimeters bellow the mud.. Not 28 feed ! But still.. It was very difficult task.. Sory for my english..


That post made me remember the Stonehenge scene in spinal tap.
 
fadecfault
Posts: 164
Joined: Mon Nov 05, 2007 8:44 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 12:08 pm

rheinwaldner wrote:
fadecfault wrote:
He's trying to argue that because mcas moves in increments rather than a single continual application that it would not be considered a runway trim situation.

No, the argument is not the incremental activation but the fact, that it stopped immediately by applying manual trim on the yoke.

--> Stopped automatic trim ≠ trim runaway.


1 Control column. . . . . . . . . . . . . . . . . Hold firmly
2 Autopilot (if engaged) . . . . . . . . . . . . .Disengage
Do not re-engage the autopilot.
Control airplane pitch attitude manually with
control column and main electric trim as
needed.
3 If the runaway stops:
-------------
4 If the runaway continues:
STAB TRIM CUTOUT
switches (both) . . . . . . . . . . . . . . . . CUTOUT

That right there says to cut the switches when the manual trim failed to stop the stab from moving again. Just because it took several seconds to be reactivated means nothing.
The views and opinions written here are my own and do not reflect those of my employer.
 
CBRboy
Posts: 177
Joined: Mon Apr 30, 2007 2:03 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 1:15 pm

blrsea wrote:
How long do they typically take to analyze the CVR, and release it into public domain? Do they usually release the full cockpit conversations transcript relating to the incident ? Or just brief summary?

I think if you reflect on who 'they' are, you would realise that the investigating authority in this case is not the same as in any other recent crash, so there isn't a 'typically'. :-)
 
User avatar
trpmb6
Posts: 2478
Joined: Thu Apr 19, 2018 5:45 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 1:36 pm

CBRboy wrote:
blrsea wrote:
How long do they typically take to analyze the CVR, and release it into public domain? Do they usually release the full cockpit conversations transcript relating to the incident ? Or just brief summary?

I think if you reflect on who 'they' are, you would realise that the investigating authority in this case is not the same as in any other recent crash, so there isn't a 'typically'. :-)


In the case of the Air France crash we even got to listen to the recording, including the very last words "10 Degrees pitch?" It's fairly ghoulish listening to the last words of a doomed flight. And the Air France crash was in pitch black, nosed up and they weren't even aware that they were moments from impacting the ocean. In the case of the lion air flight, I'm almost certain they saw the ocean coming towards them. I suspect the CVR in the last seconds to be quite terrifying to listen to. And to be quite honest, I'm not sure I even want to hear it myself.
 
SimpleFlying
Posts: 29
Joined: Thu Nov 08, 2018 8:19 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 3:39 pm

After reading through most of the posts here, I am in the opinion that the pilots should've been able to figure out that to stop the MCAS nose down pitch command is to hit the STAB TRIM CUTOUT; just like the pilots of the previous flight.

However, on the ther hand, Boeing should have also designed the MCAS system to know if there is AOA disagreement and give the pilots the warning and tell the pilots to 1) hit the STAB TRIM CUTOUT, 2) fly pitch/thrust, and 3) land at the nearest airport.

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