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smaragdz
Posts: 41
Joined: Fri Aug 03, 2007 9:48 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 6:52 pm

fadecfault wrote:
Obviously this is not normal behavior and should have resulted in the pilots hitting the switches.
But he wants to argue that steps ≠ continual.


Exactly, it was not even normal behaviour for a runaway stab trim scenario, adding to the confusion. Without the great deal of hindsight available to us it is very difficult to blame a crew for not understanding the situation.
 
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7BOEING7
Posts: 3039
Joined: Fri Oct 12, 2012 5:28 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 6:58 pm

smaragdz wrote:
fadecfault wrote:
Obviously this is not normal behavior and should have resulted in the pilots hitting the switches.
But he wants to argue that steps ≠ continual.


Exactly, it was not even normal behaviour for a runaway stab trim scenario, adding to the confusion. Without the great deal of hindsight available to us it is very difficult to blame a crew for not understanding the situation.


You don’t need to understand everything, you need to fly the airplane not let it fly you.
 
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PixelFlight
Posts: 1033
Joined: Thu Nov 08, 2018 11:09 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 8:12 pm

FlyXLsa wrote:
On Boeing; It doesn't seem hard to me to revise the code to "AoA = Disagree then MCAS = Off"

Easy to say, but as the 737 avionic is split in two, left side and right side, without communication between the two, it will be difficult to generate a AoA disagree on each FCC. The displays have the information from the two ADIRUs and can generate a AoA disagree message, but I doubt that a display can be certified to forward a input signal to the FCCs. Still, I am certain that Boeing will have a solution, but I suspect that it will require more than a easy condition added to the software code.
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:
 
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FlyXLsa
Posts: 59
Joined: Thu Dec 27, 2018 5:03 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 9:00 pm

PixelFlight wrote:
FlyXLsa wrote:
On Boeing; It doesn't seem hard to me to revise the code to "AoA = Disagree then MCAS = Off"

Easy to say, but as the 737 avionic is split in two, left side and right side, without communication between the two, it will be difficult to generate a AoA disagree on each FCC. The displays have the information from the two ADIRUs and can generate a AoA disagree message, but I doubt that a display can be certified to forward a input signal to the FCCs. Still, I am certain that Boeing will have a solution, but I suspect that it will require more than a easy condition added to the software code.


I kept it simple on all levels so we don't go down the SMYD1/2/ADIRU rabbit hole and all that entails hoping to avoid those previously discussed topics. I read Boeing is working on a software patch and that was what I was alluding towards.
Whiskey-Oscar-Oscar-Foxtrot
 
PlanesNTrains
Posts: 9524
Joined: Tue Feb 01, 2005 4:19 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 9:45 pm

7BOEING7 wrote:
smaragdz wrote:
fadecfault wrote:
Obviously this is not normal behavior and should have resulted in the pilots hitting the switches.
But he wants to argue that steps ≠ continual.


Exactly, it was not even normal behaviour for a runaway stab trim scenario, adding to the confusion. Without the great deal of hindsight available to us it is very difficult to blame a crew for not understanding the situation.


You don’t need to understand everything, you need to fly the airplane not let it fly you.


Of course. However, pilots shouldn’t be setup for failure, and from the outside it would appear that the new MCAS system, with its lack of redundancy, did exactly that.

That doesn’t mean that the pilots aren’t primarily responsible.
-Dave


MAX’d out on MAX threads. If you are starting a thread, and it’s about the MAX - stop. There’s already a thread that covers it.
 
CO953
Posts: 523
Joined: Tue Jan 08, 2013 4:05 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 10:16 pm

Well I've purposely been reading and not commenting for awhile now, but have read every page of the thread.

The one thing I'd like to contribute today, as sort of a "centering," big-picture comment, is that:

Yes, I have read the back-and-forth for 54 pages now. For quite awhile now, awaiting recovery of the CVR, much of it has centered on supposition of the pilots' reactions, vis a vis how the previous crew handled the trim anomalies.

I have also read a lot of arguing about MCAS, and whether it was at fault, or whether the pilots should have recognized the situation earlier.

Way back earlier in the first few pages of the thread, I said that - to me - a critical part of the chain of events was the altitude. They were on take-off and didn't have much to play with. This is why I will be very hesitant to start pinning things on the crew. What bothers me a lot about the MCAS setup is the fact that it was designed to avoid pilot error pertaining to stall situations, but it isn't clear to me that there was sufficient risk analysis that went into its design to decide which was more dangerous: a crew losing control in an pitch-up scenario due to drag from the engine placement, or having a computerized system start second-guessing the pilots at a low altitude, considering that a sensor failure could queer the algorithm and induce improper control-surface movements. Fighting/diagnosing the computer in real time, at a low altitude, seems like it's just asking for a very bad end.

Blame the pilots all you want, but the AF447 crew had a heck of a lot more altitude to figure things out, and sadly they didn't until it was too late. But with Lion Air, imagine all of these envelope-altering actions taking place at low altitude after take-off. Maybe MCAS should be given a minimum altitude, below which it cannot engage, no matter the sensor inputs, so as to give the crew a chance to fly the airplane old-school method, and possibly recover it.

The CVR, if it is readable, should tell the tale.

RIP to all aboard.
 
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litz
Posts: 2383
Joined: Wed Dec 24, 2003 6:01 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Wed Jan 16, 2019 11:31 pm

FlyXLsa wrote:
PixelFlight wrote:
FlyXLsa wrote:
On Boeing; It doesn't seem hard to me to revise the code to "AoA = Disagree then MCAS = Off"

Easy to say, but as the 737 avionic is split in two, left side and right side, without communication between the two, it will be difficult to generate a AoA disagree on each FCC. The displays have the information from the two ADIRUs and can generate a AoA disagree message, but I doubt that a display can be certified to forward a input signal to the FCCs. Still, I am certain that Boeing will have a solution, but I suspect that it will require more than a easy condition added to the software code.


I kept it simple on all levels so we don't go down the SMYD1/2/ADIRU rabbit hole and all that entails hoping to avoid those previously discussed topics. I read Boeing is working on a software patch and that was what I was alluding towards.


Southwest has already changed their MAX specification to include exactly what you are describing, including a DISAGREE warning on the AoA indicators.

The problem in this incident is, you have to have ordered line items on the MAX spec that LionAir did not order.

In Southwest's case, that's the HUD. LionAir's MAX spec does not include the HUD.

The airplane in this incident literally did not have the instrumentation to either show, or display, a disagree warning.

Dunno exactly how to solve that ... maybe we'll see a change to the minimum allowed spec on the airplane?

I'm sure the eventual final report on this crash will contain several recommendations, just have to wait and see what they are.
 
sgrow787
Posts: 450
Joined: Fri May 16, 2014 8:12 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 1:16 am

trpmb6 wrote:
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.


I said the same thing myself. Then my coworker said this: "You know, if it was mandatory listening for people who worked on that plane, and you worked on that plane, then maybe listening to it will make you work harder to make things safer the next time." That certainly seems logical to me. And if that's the case, should we all in aerospace, who design and operate these planes, make it mandatory listening??
Just one sensor,
Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
Oo-oo-ooh.
 
SimpleFlying
Posts: 29
Joined: Thu Nov 08, 2018 8:19 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 1:38 am

litz wrote:
Southwest has already changed their MAX specification to include exactly what you are describing, including a DISAGREE warning on the AoA indicators.

The problem in this incident is, you have to have ordered line items on the MAX spec that LionAir did not order.

In Southwest's case, that's the HUD. LionAir's MAX spec does not include the HUD.

The airplane in this incident literally did not have the instrumentation to either show, or display, a disagree warning.

Dunno exactly how to solve that ... maybe we'll see a change to the minimum allowed spec on the airplane?

I'm sure the eventual final report on this crash will contain several recommendations, just have to wait and see what they are.


I believe AoA disagreement warning should be standard regardless whether the airline order the AoA value display or not.

AoA sensors data is ultimately used to determine stall condition which is a flight safety matter. So it makes sense for the flight system to give warning to the pilots and direct the pilots to appropriate NNC check list in the event of AoA disagreement.
 
mzlin
Posts: 140
Joined: Sat Mar 31, 2012 6:32 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 3:05 am

CO953 wrote:
Well I've purposely been reading and not commenting for awhile now, but have read every page of the thread.

The one thing I'd like to contribute today, as sort of a "centering," big-picture comment, is that:

Yes, I have read the back-and-forth for 54 pages now. For quite awhile now, awaiting recovery of the CVR, much of it has centered on supposition of the pilots' reactions, vis a vis how the previous crew handled the trim anomalies.

I have also read a lot of arguing about MCAS, and whether it was at fault, or whether the pilots should have recognized the situation earlier.

Way back earlier in the first few pages of the thread, I said that - to me - a critical part of the chain of events was the altitude. They were on take-off and didn't have much to play with. This is why I will be very hesitant to start pinning things on the crew. What bothers me a lot about the MCAS setup is the fact that it was designed to avoid pilot error pertaining to stall situations, but it isn't clear to me that there was sufficient risk analysis that went into its design to decide which was more dangerous: a crew losing control in an pitch-up scenario due to drag from the engine placement, or having a computerized system start second-guessing the pilots at a low altitude, considering that a sensor failure could queer the algorithm and induce improper control-surface movements. Fighting/diagnosing the computer in real time, at a low altitude, seems like it's just asking for a very bad end.

Blame the pilots all you want, but the AF447 crew had a heck of a lot more altitude to figure things out, and sadly they didn't until it was too late. But with Lion Air, imagine all of these envelope-altering actions taking place at low altitude after take-off. Maybe MCAS should be given a minimum altitude, below which it cannot engage, no matter the sensor inputs, so as to give the crew a chance to fly the airplane old-school method, and possibly recover it.

The CVR, if it is readable, should tell the tale.

RIP to all aboard.


It has been pointed out by others that the MCAS system was required for certification under FAR requirements for longitudinal stability; that is increasing thrust shouldn't make the plane pitch up on its own, and MCAS was to prevent that. So to Boeing it wasn't subject to an analysis or relative risk; it was required to meet a mandatory certification requirement. If it were not for that requirement, then no MCAS would be fine; you'd just get a stall warning when the pitch up causes an approach to stall.
 
salttee
Posts: 3149
Joined: Wed Jul 13, 2016 3:26 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 3:23 am

Too much meddling by the FAA?
 
PlanesNTrains
Posts: 9524
Joined: Tue Feb 01, 2005 4:19 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 3:44 am

Is it the FAA’s job to design the system though? Or is the suggestion that they told Boeing “no need to build in redundancy or warnings”?

It’s interesting that the FAA may both over-meddle and under-meddle. It should all come out in the investigation.
-Dave


MAX’d out on MAX threads. If you are starting a thread, and it’s about the MAX - stop. There’s already a thread that covers it.
 
PlanesNTrains
Posts: 9524
Joined: Tue Feb 01, 2005 4:19 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 3:47 am

litz wrote:
FlyXLsa wrote:
PixelFlight wrote:
Easy to say, but as the 737 avionic is split in two, left side and right side, without communication between the two, it will be difficult to generate a AoA disagree on each FCC. The displays have the information from the two ADIRUs and can generate a AoA disagree message, but I doubt that a display can be certified to forward a input signal to the FCCs. Still, I am certain that Boeing will have a solution, but I suspect that it will require more than a easy condition added to the software code.


I kept it simple on all levels so we don't go down the SMYD1/2/ADIRU rabbit hole and all that entails hoping to avoid those previously discussed topics. I read Boeing is working on a software patch and that was what I was alluding towards.


Southwest has already changed their MAX specification to include exactly what you are describing, including a DISAGREE warning on the AoA indicators.

The problem in this incident is, you have to have ordered line items on the MAX spec that LionAir did not order.

In Southwest's case, that's the HUD. LionAir's MAX spec does not include the HUD.

The airplane in this incident literally did not have the instrumentation to either show, or display, a disagree warning.

Dunno exactly how to solve that ... maybe we'll see a change to the minimum allowed spec on the airplane?

I'm sure the eventual final report on this crash will contain several recommendations, just have to wait and see what they are.


I’m curious how those line item decisions are made? For example, does LionAir go through and line item veto things to save money, or do they tell Boeing to sharpen their pencil and Boeing says “Well...you don’t really NEED this here subsystem”?
-Dave


MAX’d out on MAX threads. If you are starting a thread, and it’s about the MAX - stop. There’s already a thread that covers it.
 
ikramerica
Posts: 15174
Joined: Mon May 23, 2005 9:33 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 5:19 am

PlanesNTrains wrote:
Is it the FAA’s job to design the system though? Or is the suggestion that they told Boeing “no need to build in redundancy or warnings”?

It’s interesting that the FAA may both over-meddle and under-meddle. It should all come out in the investigation.

Air bags save more lives than they take, but no mistake, they do kill people. And not just because they are defective.

Seat belts save a lot of lives. But they also trap you. People have drown due to them. Been burned alive. I personally witnessed someone who was thrown from his car and lived when he turned in front of a light rail and it smashed into his Volvo. The driver side was compressed completely to the transmission tunnel. Had he been in a seatbelt I would have witnessed a death.

The point is that safety measures are required because they are net positive.
Of all the things to worry about... the Wookie has no pants.
 
rheinwaldner
Posts: 1875
Joined: Wed Jan 02, 2008 4:58 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 7:34 am

fadecfault wrote:
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:
CHECKLIST COMPLETED
-------------
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.

I have added the "Checklist completed" line item after point 3, that you conveniently left away. It means that in the large majority of the MCAS trim cycles, the pilots did follow this memory item checklist and did 100% comply with it:
1. The trim started moving
2. The autopilot was disengaged, and they controlled the airplane manually with the control column and the main electric trim as needed
3. The runaway stopped -> "checklist completed".

On the following picture the relevant events are extracted:
Image

(1) These are the manual main electric trim inputs (mainly nose up)

(2) These are the MCAS induced nose down trim inputs

(3) Totally 23 times (21 in a row) the runaway stabilizer checklist was done with line item 3 after the runaway stopped -> "checklist completed"

(4) This was the first full MCAS cycle, that went without manual interruption. At that point they stood with one foot in the grave. But during the next MCAS cycle the manual input that stopped the MCAS input was there already, so even during that final time going through the above checklist has ended at line item 3 -> "checklist completed". Then another MCAS cycle was triggered, that was unopposed, so the stabilizer finally stopped at the full nose down position and the aircraft was unrecoverable.

So statements like "they were not flying" or "they did not follow known procedures" at max could made about the two unopposed MCAS cycles at the end. The rest was flying to the textbook, fully compliying with the NNC. In fact, if you run the NNC stubbornly to the end, you will never reach line item 4. The runaway always stops, when trimming manually. So every time, sticking strictly to the NNC would mean -> "checklist completed" at line item 3. In a sense, the pilots of the flight before did not follow the NNC as accurate, because they missed, that using manual electric trim the MCAS would stop.
You also have to remember, how humans work. If you do something 21 times and each time you find the trim to stop immediately after you give manual opposite trim, your mind must have come to the conclusion, that trim runaway is not your problem.

(5) And there is this one: during the time, when the first full uninterrupted MCAS passed by, the plane seems to have started a turn (see heading change). And during turns it is bad practice to trim. Applying pitch trim during a turn means, that after the turn you end up in an unpredictable trim state. So my theory is, that as during the turns trim input is not done at all or only sparsely, the MCAS was able to do its two full, deadly cycles.
Many things are difficult, all things are possible!
 
fadecfault
Posts: 164
Joined: Mon Nov 05, 2007 8:44 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 8:41 am

rheinwaldner wrote:
fadecfault wrote:
rheinwaldner wrote:
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:
CHECKLIST COMPLETED
-------------
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.

I have added the "Checklist completed" line item after point 3, that you conveniently left away. It means that in the large majority of the MCAS trim cycles, the pilots did follow this memory item checklist and did 100% comply with it:
1. The trim started moving
2. The autopilot was disengaged, and they controlled the airplane manually with the control column and the main electric trim as needed
3. The runaway stopped -> "checklist completed".

On the following picture the relevant events are extracted:
Image

(1) These are the manual main electric trim inputs (mainly nose up)

(2) These are the MCAS induced nose down trim inputs

(3) Totally 23 times (21 in a row) the runaway stabilizer checklist was done with line item 3 after the runaway stopped -> "checklist completed"

(4) This was the first full MCAS cycle, that went without manual interruption. At that point they stood with one foot in the grave. But during the next MCAS cycle the manual input that stopped the MCAS input was there already, so even during that final time going through the above checklist has ended at line item 3 -> "checklist completed". Then another MCAS cycle was triggered, that was unopposed, so the stabilizer finally stopped at the full nose down position and the aircraft was unrecoverable.

So statements like "they were not flying" or "they did not follow known procedures" at max could made about the two unopposed MCAS cycles at the end. The rest was flying to the textbook, fully compliying with the NNC. In fact, if you run the NNC stubbornly to the end, you will never reach line item 4. The runaway always stops, when trimming manually. So every time, sticking strictly to the NNC would mean -> "checklist completed" at line item 3. In a sense, the pilots of the flight before did not follow the NNC as accurate, because they missed, that using manual electric trim the MCAS would stop.
You also have to remember, how humans work. If you do something 21 times and each time you find the trim to stop immediately after you give manual opposite trim, your mind must have come to the conclusion, that trim runaway is not your problem.

(5) And there is this one: during the time, when the first full uninterrupted MCAS passed by, the plane seems to have started a turn (see heading change). And during turns it is bad practice to trim. Applying pitch trim during a turn means, that after the turn you end up in an unpredictable trim state. So my theory is, that as during the turns trim input is not done at all or only sparsely, the MCAS was able to do its two full, deadly cycles.

Nice graph leaving out the runway trim on takeoff causing a nose dive. Of course that would not fit your narrative.
If you can not understand that the stab trim continued after using manual trim then there's no point arguing any further.
The views and opinions written here are my own and do not reflect those of my employer.
 
fadecfault
Posts: 164
Joined: Mon Nov 05, 2007 8:44 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 9:13 am

rheinwaldner wrote:
fadecfault wrote:
rheinwaldner wrote:
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:
CHECKLIST COMPLETED
-------------
4 If the runaway continues:
STAB TRIM CUTOUT
switches (both) . . . . . . . . . . . . . . . . CUTOUT

.

You just decided on your own to add "check list completed"
between steps 3 and 4?
Do you even have access to an actual qrh or fcom?
Here's a copy. Your welcome.
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
If the runaway continues:
Stabilizer
trim wheel . . . . . . . . . . Grasp and hold
- - - - - - - - - - - - - - - - - - - - - - -
5 Stabilizer . . . . . . . . . . . . . . . . . . . Trim manually
6 Anticipate trim requirements.
7 Checklist Complete Except Deferred Items
The views and opinions written here are my own and do not reflect those of my employer.
 
User avatar
PixelFlight
Posts: 1033
Joined: Thu Nov 08, 2018 11:09 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 9:34 am

rheinwaldner wrote:
fadecfault wrote:
3 If the runaway stops:
CHECKLIST COMPLETED

If you can not understand that the stab trim continued after using manual trim then there's no point arguing any further.

I respect you all. I think we now all understand exactly where the confusion is for the crew as we observe the same confusion on this thread:
1) repetitive discontinuous == continuous ? The checklist must be implemented at a larger time scale than the independent items, in the spirit of fixing a general issue.
2) repetitive discontinuous != continuous ? The checklist must be implemented very exactly step by step as written. focusing on exactitude.
Before the EAD was issued, this could be matter of interpretation, as we observe in this forum.

CVR will hopefully give a clue about how the crew react, the finding in the preliminary report already draw a situation where there was many confusing messages, stick shaker and control problems. Francly speaking, my point of view is that the aircraft itself was in a confusing state not exterminated while designed, increasing the stress and workload on the crew to the point that it might confuse some of them. All safety aspects involved in this accident must be improved, from design to training.
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:
 
fadecfault
Posts: 164
Joined: Mon Nov 05, 2007 8:44 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 9:57 am

fadecfault wrote:
rheinwaldner wrote:
fadecfault wrote:

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:
CHECKLIST COMPLETED
-------------
4 If the runaway continues:
STAB TRIM CUTOUT
switches (both) . . . . . . . . . . . . . . . . CUTOUT

.

You just decided on your own to add "check list completed"
between steps 3 and 4?
Do you even have access to an actual qrh or fcom?
Here's a copy. Your welcome.
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
If the runaway continues:
Stabilizer
trim wheel . . . . . . . . . . Grasp and hold
- - - - - - - - - - - - - - - - - - - - - - -
5 Stabilizer . . . . . . . . . . . . . . . . . . . Trim manually
6 Anticipate trim requirements.
7 Checklist Complete Except Deferred Items



I stand corrected the □□□□ means checklist completed. However from the QRH :
"The flight crew must be aware that checklists cannot be created for all conceivable
situations and are not intended to replace good judgment. In some situations, at the
captain’s discretion, deviation from a checklist may be needed."
The views and opinions written here are my own and do not reflect those of my employer.
 
smartplane
Posts: 1720
Joined: Fri Aug 03, 2018 9:23 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 11:22 am

Given the confusion of contributors, most of whom are not flying a misbehaving aircraft at low altitude, with different behaviour and readings left and right, at the same time as posting, cockpit confusion seems inevitable.
 
User avatar
trpmb6
Posts: 3018
Joined: Thu Apr 19, 2018 5:45 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 1:43 pm

rheinwaldner wrote:
Image


As an engineer, I see the repetitive automatic Trim inputs and say that that is a runaway trim situation. Maybe after two times happening I wouldn't have thought so. But on the third time, I would have said to my self: What I'm doing is not correcting the overall situation. To go on and tell me that someone would do the same thing 20+ times and not think to hit the cutoff switches just seems absurd. Furthermore, you know it's happening on repeat intervals, so why would you then try to make a maneuver?

In regards to the MCAS system working at low altitude. This is why the MCAS system is tied into the position of the flaps. It is only active if Flaps are stowed. That's why we see when the flaps were re-extended during their initial take off climb the automatic trim operations stopped. This is another key thing the pilots seemed to miss, even though they originally correctly identified that when they stowed flaps they immediately saw a trim operation nudging those nose back down - so they did the logical thing, return the plane back to the last known safe state and they continued climb.

I get that there can be confusion and anxiety in the heat of the moment - just listen to the Air France 447 CVR. But I just don't see how anyone can interpret 20 instances of automatic trim as anything but runaway trim.
 
SimpleFlying
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 2:19 pm

trpmb6 wrote:
As an engineer, I see the repetitive automatic Trim inputs and say that that is a runaway trim situation. Maybe after two times happening I wouldn't have thought so. But on the third time, I would have said to my self: What I'm doing is not correcting the overall situation. To go on and tell me that someone would do the same thing 20+ times and not think to hit the cutoff switches just seems absurd. Furthermore, you know it's happening on repeat intervals, so why would you then try to make a maneuver?

In regards to the MCAS system working at low altitude. This is why the MCAS system is tied into the position of the flaps. It is only active if Flaps are stowed. That's why we see when the flaps were re-extended during their initial take off climb the automatic trim operations stopped. This is another key thing the pilots seemed to miss, even though they originally correctly identified that when they stowed flaps they immediately saw a trim operation nudging those nose back down - so they did the logical thing, return the plane back to the last known safe state and they continued climb.

I get that there can be confusion and anxiety in the heat of the moment - just listen to the Air France 447 CVR. But I just don't see how anyone can interpret 20 instances of automatic trim as anything but runaway trim.


In general I agree with you. How come the pilot didn't get it? They should've realized that whatever they were doing did not solve the issue.

However, I also believe thay confusion and anxiety affected their trouble shooting and decision making capability. I don't know if I would've done better than them in the same situation.

Therefore, the system should've given the pilots warning of AoA disagree and directed them to a fail safe procedure like 1) STAB TRIM CUTOUT, 2) FLY PITCH/THRUST, 3) LAND NEAREST AIRPORT.

My reasoning for this is that AoA sensors' data is ultimately used to determine stall condition which is a flight safety matter. So if sensors/data related to flight safety becomes erroneous the aircraft becomes unsafe to fly and must land immediately.
 
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 2:31 pm

SimpleFlying wrote:
In general I agree with you. How come the pilot didn't get it? They should've realized that whatever they were doing did not solve the issue.

However, I also believe thay confusion and anxiety affected their trouble shooting and decision making capability. I don't know if I would've done better than them in the same situation.

Therefore, the system should've given the pilots warning of AoA disagree and directed them to a fail safe procedure like 1) STAB TRIM CUTOUT, 2) FLY PITCH/THRUST, 3) LAND NEAREST AIRPORT.

My reasoning for this is that AoA sensors' data is ultimately used to determine stall condition which is a flight safety matter. So if sensors/data related to flight safety becomes erroneous the aircraft becomes unsafe to fly and must land immediately.



Ultimately, that's why we need the CVR to understand their interpretation of the issue.

In regards to AOA. They were flying straight and level. So I suspect they were already flying pitch/thrust as they had communicated to ATC they were having control issues and requested to maintain their heading. We have the hindsight of knowing the AOA disagreed which was impacting the MCAS system. I don't know if the pilots, having known they had an AOA disagree, without knowledge of the MCAS system, would have interpreted their situation differently. I say that in the context that they were flying straight and level, and were maintaining that. So they were likely ignoring any AOA data they were getting anyways.
 
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 2:47 pm

trpmb6 wrote:
Ultimately, that's why we need the CVR to understand their interpretation of the issue.

In regards to AOA. They were flying straight and level. So I suspect they were already flying pitch/thrust as they had communicated to ATC they were having control issues and requested to maintain their heading. We have the hindsight of knowing the AOA disagreed which was impacting the MCAS system. I don't know if the pilots, having known they had an AOA disagree, without knowledge of the MCAS system, would have interpreted their situation differently. I say that in the context that they were flying straight and level, and were maintaining that. So they were likely ignoring any AOA data they were getting anyways.


I agree that the pilots didn't know that their AoA sensors/data disagreed, that's why the system should've been designed to give AoA disagreement warning as mandatory feature not an option (as some said that AoA indication is optional).

And with AoA disagreement, as I said before, that system should give the pilots a fail safe procedures which in essence isolating all automatic functions that depend on AoA sensors/data. In this case a procedure in the line of 1) STAB TRIM CUTOUT, 2) FLY PITCH/THRUST, 3) LAND IMMEDIATELY.

This way the pilots just follow one simple procedure and take out the guess / trial & error work.
 
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PixelFlight
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 3:23 pm

SimpleFlying wrote:
trpmb6 wrote:
Ultimately, that's why we need the CVR to understand their interpretation of the issue.

In regards to AOA. They were flying straight and level. So I suspect they were already flying pitch/thrust as they had communicated to ATC they were having control issues and requested to maintain their heading. We have the hindsight of knowing the AOA disagreed which was impacting the MCAS system. I don't know if the pilots, having known they had an AOA disagree, without knowledge of the MCAS system, would have interpreted their situation differently. I say that in the context that they were flying straight and level, and were maintaining that. So they were likely ignoring any AOA data they were getting anyways.


I agree that the pilots didn't know that their AoA sensors/data disagreed, that's why the system should've been designed to give AoA disagreement warning as mandatory feature not an option (as some said that AoA indication is optional).

And with AoA disagreement, as I said before, that system should give the pilots a fail safe procedures which in essence isolating all automatic functions that depend on AoA sensors/data. In this case a procedure in the line of 1) STAB TRIM CUTOUT, 2) FLY PITCH/THRUST, 3) LAND IMMEDIATELY.

This way the pilots just follow one simple procedure and take out the guess / trial & error work.

A redundant AoA sensor will be even more appropriate, as it will properly notice the pilot (and maintenance) without increasing stress or workload, and without others disagree messages, autopilot disconnect, or stick shaker, and most critically without inducing erratic MCAS actions. I challenge to find a safer fix for that problem.
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:
 
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SomebodyInTLS
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 3:31 pm

trpmb6 wrote:
rheinwaldner wrote:
Image


As an engineer, I see the repetitive automatic Trim inputs and say that that is a runaway trim situation. Maybe after two times happening I wouldn't have thought so. But on the third time, I would have said to my self: What I'm doing is not correcting the overall situation. To go on and tell me that someone would do the same thing 20+ times and not think to hit the cutoff switches just seems absurd.


I think we can all agree that the uncommanded trim was repeatedly causing issues and that using the cut out switches would have (helped) solve their situation, however:

1) it was not, by definition, "runaway trim" since that has both a different cause and different effects

2) a crew is trained to use procedures to solve problems and not randomly throw switches on a hunch

3) the trim was not the only thing causing them issues at the time. We know now that it was probably what ultimately led to the crash, but that's in hindsight - people need to realise that it was just one of a number of unusual messages and behaviours of the aircraft, easy to think the trim reacting is just a response to something else going wrong (which of course it was) and that cutting it out might just add to your problems...
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ikramerica
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 3:37 pm

SimpleFlying wrote:
trpmb6 wrote:
Ultimately, that's why we need the CVR to understand their interpretation of the issue.

In regards to AOA. They were flying straight and level. So I suspect they were already flying pitch/thrust as they had communicated to ATC they were having control issues and requested to maintain their heading. We have the hindsight of knowing the AOA disagreed which was impacting the MCAS system. I don't know if the pilots, having known they had an AOA disagree, without knowledge of the MCAS system, would have interpreted their situation differently. I say that in the context that they were flying straight and level, and were maintaining that. So they were likely ignoring any AOA data they were getting anyways.


I agree that the pilots didn't know that their AoA sensors/data disagreed, that's why the system should've been designed to give AoA disagreement warning as mandatory feature not an option (as some said that AoA indication is optional).

And with AoA disagreement, as I said before, that system should give the pilots a fail safe procedures which in essence isolating all automatic functions that depend on AoA sensors/data. In this case a procedure in the line of 1) STAB TRIM CUTOUT, 2) FLY PITCH/THRUST, 3) LAND IMMEDIATELY.

This way the pilots just follow one simple procedure and take out the guess / trial & error work.

And that’s why it’s a Lion Air failure.

1. Things break
2. Things don’t behave right when they break
3. When something break you fix it
4. After you fix something, you inform the next user of what happened

Lion Air attempted 3. After many tries they didn’t get it right.
Lion didn’t tell the next pilots about what happened and what the previous crew did to stop it. So they failed 4.

Is there a design flaw? Probably. Was it unrecoverable? No.

Hindsight is easy when we aren’t in the pilot seat. But this wasn’t an isolated event. The same f-ing thing just happened the night before. Many people died because the plane was dispatched without a confirmed fixed and the pilots the next day were not even informed of what the previous pilots did to correct the problem.

Has anyone ever borrowed a car that had and issue or lent your car to someone when your car had an issue? I have both ways. And I inform the borrower that there’s something to be aware of. And I’ve been informed. And that’s just a car that you can pull off the road if you need to.

As for this inane concepts of 20 repeated malfunctions in a short time is not “continuous”, that’s ludicrous. We live in a digital age. Digital means on/off. Continuous in the digital age often means repeated continually. If something keeps happening over and over that you don’t want, and you have a means to permanently stop it until you can figure out why, you do so. Period. Failure to do is your fault. There were two pilots and a mechanic in the cockpit. Despite the low altitude there was enough time for one of them to do this considering the mechanic should have know the previous crew did exactly that. If the mechanic didn’t know what the previous crew did either, how is that not squarely on Lion and their crappy chain of command?
Of all the things to worry about... the Wookie has no pants.
 
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 3:49 pm

ikramerica wrote:
There were two pilots and a mechanic in the cockpit. Despite the low altitude there was enough time for one of them to do this considering the mechanic should have know the previous crew did exactly that. If the mechanic didn’t know what the previous crew did either, how is that not squarely on Lion and their crappy chain of command?


Just to clarify, the mechanic was not in the jump seat. He was in the main cabin.
 
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 4:21 pm

ikramerica wrote:
And that’s why it’s a Lion Air failure.

1. Things break
2. Things don’t behave right when they break
3. When something break you fix it
4. After you fix something, you inform the next user of what happened

Lion Air attempted 3. After many tries they didn’t get it right.
Lion didn’t tell the next pilots about what happened and what the previous crew did to stop it. So they failed 4.

Is there a design flaw? Probably. Was it unrecoverable? No.

Hindsight is easy when we aren’t in the pilot seat. But this wasn’t an isolated event. The same f-ing thing just happened the night before. Many people died because the plane was dispatched without a confirmed fixed and the pilots the next day were not even informed of what the previous pilots did to correct the problem.

Has anyone ever borrowed a car that had and issue or lent your car to someone when your car had an issue? I have both ways. And I inform the borrower that there’s something to be aware of. And I’ve been informed. And that’s just a car that you can pull off the road if you need to.

As for this inane concepts of 20 repeated malfunctions in a short time is not “continuous”, that’s ludicrous. We live in a digital age. Digital means on/off. Continuous in the digital age often means repeated continually. If something keeps happening over and over that you don’t want, and you have a means to permanently stop it until you can figure out why, you do so. Period. Failure to do is your fault. There were two pilots and a mechanic in the cockpit. Despite the low altitude there was enough time for one of them to do this considering the mechanic should have know the previous crew did exactly that. If the mechanic didn’t know what the previous crew did either, how is that not squarely on Lion and their crappy chain of command?


Lion Air is definitely also at fault. It could be repair lapses. It could be human behavior development issue - safety is not developed as culture at Lion Air (they got IOSA certificate nevertheless). Could be pilot training issues. Etc. At the end of the day those are human errors.

Human errors had caused accidents even in airlines that are viewed as world class. So it can happen to any airlines - frequency may be different; statistically less in more established airlines in more developed country.

With the advancement of technology, it should be relatively easy to develop a system to inform human of system errors and direct the human to follow a simple fail safe procedure. This will ensure safety and take out human error factors significantly.

My example is, as I have mentuoned before, if AoA disagree detected, give warning to the pilots, direct the pilots to a simple fail safe procedure in line with 1) STAB TRIM CUTOUT (this will ensure any automatic command that depend on the AoA data to stop giving command), 2) FLY PITCH/THRUST, 3) LAND IMMEDIATELY.

At the very least that kind of system takes out human confusion, startle effect, etc. which also ensure positive outcome. This also eliminate human analytic capability difference - given the same situation two persons may make different decisions
 
blrsea
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 4:36 pm

Do pilots check the logs to see if there was any issue reported and what was done to fix it before flying? Maybe the pilot didn't see the previous pilot's comments, just saw the mechanic's note it was fixed and left it at that? A costly mistake if true!
 
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 4:58 pm

blrsea wrote:
Do pilots check the logs to see if there was any issue reported and what was done to fix it before flying? Maybe the pilot didn't see the previous pilot's comments, just saw the mechanic's note it was fixed and left it at that? A costly mistake if true!


IIRC, there were no comments about the prior flight failure except a reference to "AoA disagree" and "problem fixed", nor any communication between the sequential crews as to what took place and how the problem was resolved. That, in isolation, is absolutely terrifying to me as a passenger. Like IK says below, I have always alerted anyone borrowing something mechanical from me as to any inherent dangers from something not working as expected. Whatever the rules and procedures at Lion or Boeing or the FAA, if I'm a captain and need to take action to save a plane and then hand fly to my destination I would make damn sure that is a red flag displayed prominently on my paperwork. Boeing and Lion have plenty of other crap to address, but that surely is something on the culture, the MX or the prior Captain himself. I have to believe that hand flying a commercial airliner all the way through to a destination is an exceedingly rare event, it should have been noted in BOLD.
 
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 5:19 pm

SimpleFlying wrote:
direct the pilots to a simple fail safe procedure in line with 1) STAB TRIM CUTOUT (this will ensure any automatic command that depend on the AoA data to stop giving command),

A problem with this is that automatic trim inputs are essential part of the design. At least part of certifiable design. Cutting off trim reduces flight envelope - and as pitch is now an uncertainty, getting into stall is more probable
It should be more like:
-slow down and descend to flaps speed and altitude
-flaps 5
(this allows for nice envelope edges as far as I understand)
-trim off.

At the very least, this sends ETOPS down the drain as flight times are now at flaps down speed - all due to a single failure, and mainland-hawaii requires more than ETOPS 240 as flaps limits are FL200, 170 KIAS, and fuel consumption would go way up.
 
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 5:32 pm

ikramerica wrote:
1. Things break
2. Things don’t behave right when they break
3. When something break you fix it
4. After you fix something, you inform the next user of what happened

Lion Air attempted 3. After many tries they didn’t get it right.
Lion didn’t tell the next pilots about what happened and what the previous crew did to stop it. So they failed 4.

Is there a design flaw? Probably. Was it unrecoverable? No.

Hindsight is easy when we aren’t in the pilot seat. But this wasn’t an isolated event. The same f-ing thing just happened the night before. Many people died because the plane was dispatched without a confirmed fixed and the pilots the next day were not even informed of what the previous pilots did to correct the problem.

More than a design flaw. A systemic OEM failure too.

If only Boeing hadn't grandfathered the latest iteration of the 737 family, they would have been fully aware of the ongoing issues with this aircraft, through 787-style automatic status / condition reporting. Like the unusual need to replace normally reliable hardware in a near new aircraft. That two previous attempts failed. Lion technical staff would been have been contacted by Boeing support.

Did Lion tech staff initiate contact with Boeing? Hopefully the FAA will access logs from both parties.
 
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SomebodyInTLS
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 5:42 pm

ikramerica wrote:
3. When something break you fix it

Lion Air attempted 3. After many tries they didn’t get it right.


Woah! Hold it right there...

That is a massive (and AFAIK false) assumption you're making!

I believe we have yet to find any evidence that the AOA sensor was not fixed correctly... mandala499 and others have suggested the very plausible scenario that the problem lies not with the sensor itself but further into the avionics - in which case maintenance are not really at fault since it was not an abvious failure mode.
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StTim
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 6:41 pm

A question.

The previous flight popped the circuit breakers stopping automatic trim changes. At what point and on what basis were these reset.

A secondary question is why was the following flight not informed of that action?
 
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FlyXLsa
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 6:49 pm

SomebodyInTLS wrote:
[quote="trpmb6"
2) a crew is trained to use procedures to solve problems and not randomly throw switches on a hunch


Read the NTSB documents on SW1380. The Captain there only loosely followed the 737 Checklist(s), and skipped a few, deviating several times from the prescribed procedures and settings for items such as "nearest airport", flaps and airspeed. I'll fly with HER any day, every day.

Same with US1549 on the way to the Hudson. They missed a few Checklist items including the "Ditch" setting for a water landing. Again... MY kind of AVIATORS. Fly first and follow the checklist later.

What both the above crews did right was AVIATE a/k/a FLY THE FREAKIN' PLANE!

The JT610 crew failed to AVIATE. Even the JT43 crew managed to do that. Checklists should be an aid to assist a crew and NOT an end unto themselves.

If you need me to sit with you in a SIM, while holding the Nose Down Trim Tab for just under 10 seconds moving the STAB 2.7° while you PRACTICE FLIPPING TWO SWITCHES, YOU ARE NO AVIATOR. You are a checklist ticker that has no business flying a single engine Cessna yet alone a BIG JET with passengers in revenue service.

Maybe my expectations for PROFESSIONAL PILOTS are too high?

Boeing's MCAS, the failure to disclose and document the system and creating a single point failure system (what happened to FAIL SAFE?) that lead to this accident are all part of this picture too. Boeing will be held to account in court and/or by the regulators who should have never approved this design IMO. AoA displays should NOT be optional equipment and would have helped diagnose and fix this plane's issues. The checklists (AoA Disagree and Runaway Stabilizer) should probably be revised to remove any potential discrepancies. I find the argument regarding continuous vs. intermittent regarding Runaway Stabilizer bordering on the absurd, but the "Bash Boeing" crowd likes to cling to it ad nauseam.

Lion Air and Lion Air Mx and reporting system(s) (or lack thereof) do not escape critique in the KNKT preliminary report starting with "Safety Items" on page 33 and ending in the final appendixes on page 78. Just maybe after three flights with significant problem issues it would be a good idea to perform a test flight before putting the plane back into revenue service. I see from the report what appears to be a number of errors that were cleared and that the systems checked out as 'ok" but this is no substitute for a spin around the block to be certain the plane is airworthy.

Finally Rusdi Kirana and the rest of Lion Air's Management need to learn how to run an airline. I'd LOVE to see some financials on this operation given Kirana's reported personal wealth and the fact they fly brand new aircraft with a low cost model. Something doesn't add up and Kirana probably gets exactly what he pays for in terms on talent.
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FlyXLsa
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 7:05 pm

StTim wrote:
A question.
The previous flight popped the circuit breakers stopping automatic trim changes. At what point and on what basis were these reset.
A secondary question is why was the following flight not informed of that action?


According the the KNKT Preliminary report, the JT43 Crew ran three NNC's. Alt Disagree, Airspeed Disagree and Runaway Stabilizer. Flipping the Cutout Switches are part of the Runaway Stabilizer NNC as is Grab and Hold the Wheel.

The KNKT report is critical of the "poor reporting" by the JT43 crew. Apparently the only mention close to the issue they faced was entering STS Trimming the worn way in the company A-SHOR (?) system. IIRC they didn't even mention the active stick shaker or ANY NNC that were ran.

There was a conversation between the JT43 Pilot and an engineer.

After parking in Jakarta, the PIC informed the engineer about the aircraft problem and entered IAS (Indicated Air Speed) and ALT (altitude) Disagree and FEEL DIFF PRESS (Feel Differential Pressure) light problem on the Aircraft Flight Maintenance Log (AFML).

The PIC also reported the flight condition through the electronic reporting system of the company A-SHOR.
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StTim
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 7:11 pm

So who reset the switches? The engineer, who let’s remember lost his life, or the previous crew? I am assuming it wasn’t the incoming crew or they would/should have realised that was a good option.
 
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FlyXLsa
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 7:23 pm

StTim wrote:
So who reset the switches? The engineer, who let’s remember lost his life, or the previous crew? I am assuming it wasn’t the incoming crew or they would/should have realized that was a good option.


The JT43 Pilot actioned the switches very early in the flight per the report - cycling them twice only to have the problem return.
Presumably the JT610 crew did not. Also, from the power shown to the Stab Trim in the FDR Chart it appears they did not. The report makes no comment nor does Boeing.

From the KNKT Report:

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.

The pilot performed three Non-Normal Checklists (NNCs) consisting of Airspeed Unreliable, ALT DISAGREE, and Runaway Stabilizer..."
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Okie
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 7:54 pm

FlyXLsa wrote:
According the the KNKT Preliminary report, the JT43 Crew ran three NNC's. Alt Disagree, Airspeed Disagree and Runaway Stabilizer. Flipping the Cutout Switches are part of the Runaway Stabilizer NNC as is Grab and Hold the Wheel.The KNKT report is critical of the "poor reporting" by the JT43 crew. Apparently the only mention close to the issue they faced was entering STS Trimming the worn way in the company A-SHOR (?) system. IIRC they didn't even mention the active stick shaker or ANY NNC that were ran. There was a conversation between the JT43 Pilot and an engineer.After parking in Jakarta, the PIC informed the engineer about the aircraft problem and entered IAS (Indicated Air Speed) and ALT (altitude) Disagree and FEEL DIFF PRESS (Feel Differential Pressure) light problem on the Aircraft Flight Maintenance Log (AFML).The PIC also reported the flight condition through the electronic reporting system of the company A-SHOR.


My question would be what Mx was performed before the problem arose on the JT43 flight. Is there something there that could have caused this issue from a repair before the JT43 flight?

We are quite aware the AOA sensor was replaced which accomplished nothing after the JT43 flight and the sensor that was removed has gone for examination will probably indicate that the replaced sensor was operable. (that is just a guess)

I am just having a hard time believing that a AOA sensor failed and was replaced with a "new" unit that was bad.

Okie
 
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FlyXLsa
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 7:54 pm

I also assume the JT610 Crew ran the Airspeed Unreliable NNC (see below). This would explain their climb to hold at 5,000 feet (see QRH Performance Inflight Holding below) while they worked the problem with MCAS.

I'm not sure why they added flaps 5 prior to the climb to 5,000 ft, but doing so stopped MCAS. When they retracted flaps at altitude, the MCAS inputs began again just like they did upon the first flap retraction.

Flaps, the Manual Trim Tab on the wheel (they used it for a while), the Cutout Switches or simply Holding the Rotating Wheel would have stopped MCAS Nose Down Inputs.

If you "KNOW YOUR PLANE" you don't really need a checklist for any of those steps. The R/W Stab NNC is also a memory item.
Airmanship 101.

QRH Airspeed Unreliable Checklist:

https://photos.app.goo.gl/X7LUX6sVf2rDPoJc8

QRH Performance Inflight Holding:

https://photos.app.goo.gl/duYEQQmzgqRNVMW36

AND... since it's the source of A LOT of discussion here's the actual Runaway Stabilizer NNC:

https://photos.app.goo.gl/6Av9GrLGTXHMTra67

Image

Note: I'm new here and trying to figure out how to post an image in this forum?
Whiskey-Oscar-Oscar-Foxtrot
 
chicawgo
Posts: 456
Joined: Tue Nov 29, 2011 5:09 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 7:56 pm

FlyXLsa wrote:
SomebodyInTLS wrote:
[quote="trpmb6"
2) a crew is trained to use procedures to solve problems and not randomly throw switches on a hunch


Read the NTSB documents on SW1380. The Captain there only loosely followed the 737 Checklist(s), and skipped a few, deviating several times from the prescribed procedures and settings for items such as "nearest airport", flaps and airspeed. I'll fly with HER any day, every day.

Same with US1549 on the way to the Hudson. They missed a few Checklist items including the "Ditch" setting for a water landing. Again... MY kind of AVIATORS. Fly first and follow the checklist later.

What both the above crews did right was AVIATE a/k/a FLY THE FREAKIN' PLANE!

The JT610 crew failed to AVIATE. Even the JT43 crew managed to do that. Checklists should be an aid to assist a crew and NOT an end unto themselves.

If you need me to sit with you in a SIM, while holding the Nose Down Trim Tab for just under 10 seconds moving the STAB 2.7° while you PRACTICE FLIPPING TWO SWITCHES, YOU ARE NO AVIATOR. You are a checklist ticker that has no business flying a single engine Cessna yet alone a BIG JET with passengers in revenue service.

Maybe my expectations for PROFESSIONAL PILOTS are too high?

Boeing's MCAS, the failure to disclose and document the system and creating a single point failure system (what happened to FAIL SAFE?) that lead to this accident are all part of this picture too. Boeing will be held to account in court and/or by the regulators who should have never approved this design IMO. AoA displays should NOT be optional equipment and would have helped diagnose and fix this plane's issues. The checklists (AoA Disagree and Runaway Stabilizer) should probably be revised to remove any potential discrepancies. I find the argument regarding continuous vs. intermittent regarding Runaway Stabilizer bordering on the absurd, but the "Bash Boeing" crowd likes to cling to it ad nauseam.

Lion Air and Lion Air Mx and reporting system(s) (or lack thereof) do not escape critique in the KNKT preliminary report starting with "Safety Items" on page 33 and ending in the final appendixes on page 78. Just maybe after three flights with significant problem issues it would be a good idea to perform a test flight before putting the plane back into revenue service. I see from the report what appears to be a number of errors that were cleared and that the systems checked out as 'ok" but this is no substitute for a spin around the block to be certain the plane is airworthy.

Finally Rusdi Kirana and the rest of Lion Air's Management need to learn how to run an airline. I'd LOVE to see some financials on this operation given Kirana's reported personal wealth and the fact they fly brand new aircraft with a low cost model. Something doesn't add up and Kirana probably gets exactly what he pays for in terms on talent.


This is the best and most clear post I've seen describing what I believe to be the reality of the situation. I don't understand why so many people here are diminishing the expectations of pilots to mere robots that are only able to follow checklists.

Look at UA232 at Sioux City. There was no "checklist" for loss of 3rd engine and loss of all flight controls. The pilots figured out as best they could what had happened and flew the plane solely with two engines, using differential power for pitch, turn, etc. That's not something I imagine they practiced in the flightsim either. And they saved a lot of the people on board actually bringing the plane to the runway.

How can anyone possibly think that pilots' only job is to follow checklists?? Almost every airline accident occurs due to one or more unusual circumstances - the exact details of which often have never been experienced before. Whether it's lack of CRM, random freak accidents like an engine failure piercing a hole in the fuselage, landing in a river, etc. You're not giving good pilots enough credit!

And for those arguing semantics of the word "continuous," I ask... Would you say that your heard beats continuously? Even though it's technically a beat on a fairly constant interval, does it beat continuously?
 
KingOrGod
Posts: 192
Joined: Mon Jan 16, 2017 3:19 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 8:25 pm

ikramerica wrote:
SimpleFlying wrote:
trpmb6 wrote:
Ultimately, that's why we need the CVR to understand their interpretation of the issue.

In regards to AOA. They were flying straight and level. So I suspect they were already flying pitch/thrust as they had communicated to ATC they were having control issues and requested to maintain their heading. We have the hindsight of knowing the AOA disagreed which was impacting the MCAS system. I don't know if the pilots, having known they had an AOA disagree, without knowledge of the MCAS system, would have interpreted their situation differently. I say that in the context that they were flying straight and level, and were maintaining that. So they were likely ignoring any AOA data they were getting anyways.


I agree that the pilots didn't know that their AoA sensors/data disagreed, that's why the system should've been designed to give AoA disagreement warning as mandatory feature not an option (as some said that AoA indication is optional).

And with AoA disagreement, as I said before, that system should give the pilots a fail safe procedures which in essence isolating all automatic functions that depend on AoA sensors/data. In this case a procedure in the line of 1) STAB TRIM CUTOUT, 2) FLY PITCH/THRUST, 3) LAND IMMEDIATELY.

This way the pilots just follow one simple procedure and take out the guess / trial & error work.

And that’s why it’s a Lion Air failure.

1. Things break
2. Things don’t behave right when they break
3. When something break you fix it
4. After you fix something, you inform the next user of what happened

Lion Air attempted 3. After many tries they didn’t get it right.
Lion didn’t tell the next pilots about what happened and what the previous crew did to stop it. So they failed 4.

Is there a design flaw? Probably. Was it unrecoverable? No.

Hindsight is easy when we aren’t in the pilot seat. But this wasn’t an isolated event. The same f-ing thing just happened the night before. Many people died because the plane was dispatched without a confirmed fixed and the pilots the next day were not even informed of what the previous pilots did to correct the problem.

Has anyone ever borrowed a car that had and issue or lent your car to someone when your car had an issue? I have both ways. And I inform the borrower that there’s something to be aware of. And I’ve been informed. And that’s just a car that you can pull off the road if you need to.

As for this inane concepts of 20 repeated malfunctions in a short time is not “continuous”, that’s ludicrous. We live in a digital age. Digital means on/off. Continuous in the digital age often means repeated continually. If something keeps happening over and over that you don’t want, and you have a means to permanently stop it until you can figure out why, you do so. Period. Failure to do is your fault. There were two pilots and a mechanic in the cockpit. Despite the low altitude there was enough time for one of them to do this considering the mechanic should have know the previous crew did exactly that. If the mechanic didn’t know what the previous crew did either, how is that not squarely on Lion and their crappy chain of command?


Judgmental much? and maybe get your facts straight too before burning people at the stake with such greatness of hindsight...
 
hivue
Posts: 2149
Joined: Tue Feb 26, 2013 2:26 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 8:29 pm

FlyXLsa wrote:
Read the NTSB documents on SW1380. The Captain there only loosely followed the 737 Checklist(s), and skipped a few, deviating several times from the prescribed procedures and settings for items such as "nearest airport", flaps and airspeed. I'll fly with HER any day, every day.

Same with US1549 on the way to the Hudson. They missed a few Checklist items including the "Ditch" setting for a water landing. Again... MY kind of AVIATORS. Fly first and follow the checklist later.

What both the above crews did right was AVIATE a/k/a FLY THE FREAKIN' PLANE!


Heck, the Lion Air crew went them all one better and apparently skipped an entire checklist in their efforts to "aviate" the airplane back to stable flight. Look where that approach got them.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
GalaxyFlyer
Posts: 8065
Joined: Fri Jan 01, 2016 4:44 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 9:04 pm

kalvado wrote:
SimpleFlying wrote:
direct the pilots to a simple fail safe procedure in line with 1) STAB TRIM CUTOUT (this will ensure any automatic command that depend on the AoA data to stop giving command),

A problem with this is that automatic trim inputs are essential part of the design. At least part of certifiable design. Cutting off trim reduces flight envelope - and as pitch is now an uncertainty, getting into stall is more probable
It should be more like:
-slow down and descend to flaps speed and altitude
-flaps 5
(this allows for nice envelope edges as far as I understand)
-trim off.

At the very least, this sends ETOPS down the drain as flight times are now at flaps down speed - all due to a single failure, and mainland-hawaii requires more than ETOPS 240 as flaps limits are FL200, 170 KIAS, and fuel consumption would go way up.


Why on Earth would a checklist have pilots in cruise flight extend the flaps when there are STAB CUTOUT switches and the pilots cautioned on airspeed for the landing?

GF
 
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FlyXLsa
Posts: 59
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 9:30 pm

chicawgo wrote:
This is the best and most clear post I've seen describing what I believe to be the reality of the situation. I don't understand why so many people here are diminishing the expectations of pilots to mere robots that are only able to follow checklists.

Look at UA232 at Sioux City. There was no "checklist" for loss of 3rd engine and loss of all flight controls. The pilots figured out as best they could what had happened and flew the plane solely with two engines, using differential power for pitch, turn, etc. That's not something I imagine they practiced in the flightsim either. And they saved a lot of the people on board actually bringing the plane to the runway.


Thank you. UA232 is another excellent example of AVIATING. With a few of the flights that we are discussing, it may be we're exceeding the FAA's standard of "The airplane must be controllable and maneuverable, without requiring exceptional piloting skill, alertness, or strength, within the operating envelope." HOWEVER....

The issues faced by the JT610/43 crews would surely not require exceptional skills IMO. If the cruise control on my car suddenly accelerates to 95 a few seconds after I set it to 65, and then does so repeatedly, I don't need a checklist to tell me to turn the darn thing OFF.... QUICKLY I might add!

As was so eloquently stated earlier in this thread a few days ago regarding the addition of electric trim to the Cessna 150 (I'm not that old and every plane I've flown has had electric trim :D ) it is every pilot's responsibility to know how to disable the automatic systems like Trim (STS or MCAS) or Autopilot.

Airmanship 101.
Whiskey-Oscar-Oscar-Foxtrot
 
User avatar
FlyXLsa
Posts: 59
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 9:44 pm

Okie wrote:
I am just having a hard time believing that a AOA sensor failed and was replaced with a "new" unit that was bad.
Okie


That is a big mystery. It appears the 20°+/- offset can't be due to installing it in the wrong holes as i've seen there are alignment pins to ensure it is placed properly. The only two things I can think of are (1) the vane was somehow bent or damaged (dropped during installation?) or (2) Lion purchased a bad batch of non-OEM/counterfeit parts. Counterfeit Airline parts can be more lucrative than selling drugs according to one article I read recently. This is TOTAL SPECULATION on my part, but this one of the few remaining questions to be answered and I honestly don't know?
Whiskey-Oscar-Oscar-Foxtrot
 
kalvado
Posts: 3210
Joined: Wed Mar 01, 2006 4:29 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 9:52 pm

GalaxyFlyer wrote:
kalvado wrote:
SimpleFlying wrote:
direct the pilots to a simple fail safe procedure in line with 1) STAB TRIM CUTOUT (this will ensure any automatic command that depend on the AoA data to stop giving command),

A problem with this is that automatic trim inputs are essential part of the design. At least part of certifiable design. Cutting off trim reduces flight envelope - and as pitch is now an uncertainty, getting into stall is more probable
It should be more like:
-slow down and descend to flaps speed and altitude
-flaps 5
(this allows for nice envelope edges as far as I understand)
-trim off.

At the very least, this sends ETOPS down the drain as flight times are now at flaps down speed - all due to a single failure, and mainland-hawaii requires more than ETOPS 240 as flaps limits are FL200, 170 KIAS, and fuel consumption would go way up.


Why on Earth would a checklist have pilots in cruise flight extend the flaps when there are STAB CUTOUT switches and the pilots cautioned on airspeed for the landing?

GF


Because without MCAS stall performance is not there. Center of lift needs to be brought back to ensure stall onset is recoverable without assisting system.
 
GalaxyFlyer
Posts: 8065
Joined: Fri Jan 01, 2016 4:44 am

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 10:14 pm

Transport Category planes, almost without exception, have various stall protection systems—stick shakers, pushers and the like. Many have Mach trim which functions much like MCAS at the high end of the speed range adding nose up trim to counter the effects of shock waves on the wing. Neither of systems, when failed, preclude continued flight, removal of ETOPS etc, yet are all required for flight.

If MCAS were as you assume, it wouldn’t be possible to use the stab trim to stop its action or the cutout switches.

GF
 
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PixelFlight
Posts: 1033
Joined: Thu Nov 08, 2018 11:09 pm

Re: Lion Air 737MAX8 Crashed Jakarta to Pangkal Pinang

Thu Jan 17, 2019 10:17 pm

FlyXLsa wrote:
Okie wrote:
I am just having a hard time believing that a AOA sensor failed and was replaced with a "new" unit that was bad.
Okie


That is a big mystery. It appears the 20°+/- offset can't be due to installing it in the wrong holes as i've seen there are alignment pins to ensure it is placed properly. The only two things I can think of are (1) the vane was somehow bent or damaged (dropped during installation?) or (2) Lion purchased a bad batch of non-OEM/counterfeit parts. Counterfeit Airline parts can be more lucrative than selling drugs according to one article I read recently. This is TOTAL SPECULATION on my part, but this one of the few remaining questions to be answered and I honestly don't know?

There are others possibilities:
(3) The AoA sensor was not changed, this imply that the maintenance have lied or that for some foolish reason remounted the old sensor without notice it. Hard to believe.
(4) The AoA sensor input of the left ADIRU is defective and will produce a +20° offset for any AoA sensors connected to it.
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:

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