osiris30
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 4:00 am

maint123 wrote:
Too many people concentrating on how the pilots should have recovered from a faulty plane rather than what the fault was in a new plane.

5. Let's stop hoping that its a pilot or maintenance issue so that the boeing company can come out of the crash smelling like roses , and just concentrate on the information available for any conclusions.
.


WOW. Just wow. RTFM. Also read the Lehman article. You have NO idea what you are talking about and are looking to grind an axe. This is one of the worst posts I have ever read on this forum. Your own post isn't self consistent. You claim Boeing is cryptic... they are not... at all. You claim to want to wait for data but in the SAME numbered point argue against the two statistically most likely sources of the issue and the ones most backed by data thus far into the investigation.

I pray to God you are never on a jury.
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
osiris30
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 4:05 am

rheinwaldner wrote:
BravoOne wrote:
SteinarN wrote:

I too am very interested in the answer to this question. Anyone know the answer?


It's been a memory item going back as far is the first 707's. nothing new here to see, and I suspect those who really know are not talking while others demonstrate their lack of knowledge on the totality of this subject.

Then why does Boeing send a bulletin only to the MAX operators?


As a reminder. The bulletin literally said follow established procedures. You know so more people don't die. It is pretty standard after a crash for reminder bulletins to be sent. It is a "hey guys.. remember this thing... seems like you may have forgotten it... so remember it"
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
airtechy
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 4:19 am

I seem to remember a Lear Jet many years ago that had a runaway trim problem resulting in a crash .. and a mod to the trim system.
 
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Finn350
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 4:30 am

osiris30 wrote:
rheinwaldner wrote:
BravoOne wrote:

It's been a memory item going back as far is the first 707's. nothing new here to see, and I suspect those who really know are not talking while others demonstrate their lack of knowledge on the totality of this subject.

Then why does Boeing send a bulletin only to the MAX operators?


As a reminder. The bulletin literally said follow established procedures. You know so more people don't die. It is pretty standard after a crash for reminder bulletins to be sent. It is a "hey guys.. remember this thing... seems like you may have forgotten it... so remember it"


The bulletin also says: “This bulletin remains in effect until Boeing provides additional information on system updates that may allow this bulletin to be cancelled.”

I would be very surprised if there were no changes to the system in question.
 
osiris30
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 4:43 am

Finn350 wrote:
osiris30 wrote:
rheinwaldner wrote:
Then why does Boeing send a bulletin only to the MAX operators?


As a reminder. The bulletin literally said follow established procedures. You know so more people don't die. It is pretty standard after a crash for reminder bulletins to be sent. It is a "hey guys.. remember this thing... seems like you may have forgotten it... so remember it"


The bulletin also says: “This bulletin remains in effect until Boeing provides additional information on system updates that may allow this bulletin to be cancelled.”

I would be very surprised if there were no changes to the system in question.


Shall we wager on it? I see no reason to change the system. Follow procedure and it is fine. Unless you are talking about an additional warning light etc.
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
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Finn350
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 4:57 am

osiris30 wrote:
Finn350 wrote:
osiris30 wrote:

As a reminder. The bulletin literally said follow established procedures. You know so more people don't die. It is pretty standard after a crash for reminder bulletins to be sent. It is a "hey guys.. remember this thing... seems like you may have forgotten it... so remember it"


The bulletin also says: “This bulletin remains in effect until Boeing provides additional information on system updates that may allow this bulletin to be cancelled.”

I would be very surprised if there were no changes to the system in question.


Shall we wager on it? I see no reason to change the system. Follow procedure and it is fine. Unless you are talking about an additional warning light etc.


I would assume a program change concerning trim automation in certain malfunctions.
 
osiris30
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 4:59 am

Finn350 wrote:
osiris30 wrote:
Finn350 wrote:

The bulletin also says: “This bulletin remains in effect until Boeing provides additional information on system updates that may allow this bulletin to be cancelled.”

I would be very surprised if there were no changes to the system in question.


Shall we wager on it? I see no reason to change the system. Follow procedure and it is fine. Unless you are talking about an additional warning light etc.


I would assume a program change concerning trim automation in certain malfunctions.


It is possible but I believe the current mode of operation was induced due to regulatory reasons. It is more likely IMHO the existing procedures will be found to be adequate and that training or crm caused the crash.
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
Dom777
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 5:00 am

According to KNKT, AOA of Lion Air was broken.

Sent from my Redmi 5A using Tapatalk
 
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Erebus
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 5:21 am

maint123 wrote:
1. In manual mode why still have a feature in which the auto trimming comes into play ?


You might be confused with what 'manual mode' means here. I believe it just means you're not flying on autopilot and automated functions are still available.
 
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Finn350
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 5:36 am

osiris30 wrote:
Finn350 wrote:
osiris30 wrote:

Shall we wager on it? I see no reason to change the system. Follow procedure and it is fine. Unless you are talking about an additional warning light etc.


I would assume a program change concerning trim automation in certain malfunctions.


It is possible but I believe the current mode of operation was induced due to regulatory reasons. It is more likely IMHO the existing procedures will be found to be adequate and that training or crm caused the crash.


I am sure that the FAR doesn't require an aircraft to nosedive without pilot action in any situation. The longitudinal stability requirements can surely be fulfilled in other, less dangerous ways.
 
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seahawk
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 6:01 am

The logic of the AP disengaging due to unreliable sensor data, just for the automatic trim system to kick is, is a bit strange imho. Even more so if the trim system is not fed by at least 3 different AoA sensors.
 
BREECH
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 6:02 am

Starlionblue wrote:
You have a point. However pilot training is designed to repeatedly expose you to critical scenarios. The more likely and critical, the more often you see it.

Procedures are also designed so that memory items are kept to a minimum. Stabilise the aircraft, then reference a printed or on screen procedure. We are taught methods of dealing with situations, and we practice applying these methods.

The logic is that if you get something you’ve never seen you can used your knowledge and your methods to deal with it.

My point was slightly different. I'm not suggesting more or less of training. I'm suggesting more rigorous approach to designing airplanes. Maybe more thorough testing. Maybe something else, I don't know. How about putting a computer in the simulator and let them have a go at each other. I have no idea if that's even possible. What I'm trying to say is that way too many recent accidents were caused by some sort of a design flaw that was identified and the airlines may have even received "the fix" but either its implementation was postponed for some reason or the pilots didn't get the necessary training.

For example, with this Lion Air crash, WHY aren't all 737 max grounded until everything is fixed? Mind you, the manufacturer doesn't even deny that there is a problem (and THAT's a huge surprise considering the current McDonnell-Douglas corporate culture) but the FAA again follows the "promote aviation" part of their duties rather than the "control" part. How many more crashes do we need for FAA to finally be stripped of its duties as the control agency and those being transferred to NTSB?

I remember a very good film "Fight Club". Remember the scene on an airplane where the protagonist explains how car recalls work?
A new car built by my company leaves somewhere traveling at 60 mph. The rear differential locks up. The car crashes and burns with everyone trapped inside. Now, should we initiate a recall? Take the number of vehicles in the field, A, multiply by the probable rate of failure, B, multiply by the average out-of-court settlement, C. A times B times C equals X. If X is less than the cost of a recall, we don't do one.

And when asked which car company he works for, he answers, "A major one".

WHY do I have a feeling that this is exactly what's happening with Boeing? Boeing knows about their planes' defects, yet they apply the math. A certain number of crashes will mean certain financial consequences. And if those consequences are "less than X", they don't care.
No friendship, love or respect unite people as much as shared hatred.
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maint123
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 7:11 am

dragon6172 wrote:
maint123 wrote:
Too many people concentrating on how the pilots should have recovered from a faulty plane rather than what the fault was in a new plane.
1. In manual mode why still have a feature in which the auto trimming comes into play ?

FAR requirement for longitudinal stability

Thanks. Your comment led to the below link -
http://www.boeing.com/commercial/aeroma ... /fig1.html

Importantly how is the auto trimming implemented in the Max series. If auto trimming commands of up to 5 to 10 secs are being given , this flight would have no hope of recovering. Pilot I hope would have the authority to switch off this auto trimming feature , but in this particular flight time available would be critical.
 
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AirlineCritic
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 7:25 am

These are some big news, but I think some caution would probably be useful, for many different sides of the arguments above. There seems to be a tendency to either classify this as "hey stupid, follow the well-known rules" or "major failure of the aircraft design", I suspect, largely depending on how you view one particular manufacturer or the airline in question, etc.

Single failures are easy to correct, multiple failures (which they may have had) can be more troublesome... this may not have been as easy to handle. Also, automated systems (such as autotrim) will continue to exist, and, yes, perhaps shockingly to some, even B airplanes have some of these systems. And they continue to be improved and developed, based on operational experience and accident investigations.

I would not be surprised by any eventual outcome of this situation. We could, for instance, just see training recommendation. Or we could see worldwide system change in the Max trim design.
 
mandala499
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 8:01 am

Pilots know runaway stab trim and the procedures...
Pilots know flight with unreliable airspeed and the procedures...
But how many until yesterday, know how to deal with both unreliable airspeed and runaway stab trim at the same time.
And let's not assume it's day VMC at the crash location just because it's day VMC at CGK airport...
It's all very nice for us to criticize the crew, or the manufacturer... because hindsight is always 20/20, especially when we're sitting on our comfy chairs with air conditioning...
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
SteinarN
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 8:06 am

seahawk wrote:
The logic of the AP disengaging due to unreliable sensor data, just for the automatic trim system to kick is, is a bit strange imho. Even more so if the trim system is not fed by at least 3 different AoA sensors.


Exactly!
One of two pitot systems go unreliable, systems detect this and rightfully disconnect autopilot, if it was engaged, leaving control of the aircraft to the pilots. Then one of two AoA sensors is unreliable too, but now the system is programmed to assume the faulty AoA sensor is the correct working one, completely disregarding the other actually correct working AoA sensor, and then the system activates the trim system effectively doing at least as much damage as a still activated autopilot would do based on unrelaiable air speed.

This logic put simply dont give any meaning at all. It is meaningless and I am sure this will be changed to at least make the system do a sanity check of the AoA sensors - like compare them with each other - before using data from any of them in the control of the aircraft.
 
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giosue61
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 8:23 am

Going back for a second to CVR crucial point. Does it ring anything to you that it’s still missing? In 25 meters of water?
 
zakelwe
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 8:59 am

giosue61 wrote:
Going back for a second to CVR crucial point. Does it ring anything to you that it’s still missing? In 25 meters of water?


Muddy conditions down there and it maybe in other wreckage in that mud
 
Noshow
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 9:16 am

It's not acceptable anymore that recorded data cannot be retrieved easier because the storage hardware gets lost. Why not constantly radio them to some neutral place?
Weather, engine data and winds aloft can be send routinely but not the most vital data?
 
planewasted
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 10:10 am

Autonomous systems connected to flight controls should of course not act on bad sensor data. How can you argue against that? But it can happen anyway. No design is perfect, so pilots should be prepared to handle such events.

Turkish Airlines Flight 1951 crashed because of a bad sensor setting the engines to idle power and the pilots not noticing. A bit similar to this tragic crash.
 
SteinarN
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 10:15 am

Link to todays AD regarding this accident. Dont know if it has been posted earlier.
http://services.casa.gov.au/airworth/ai ... -23-51.pdf
 
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Carlos01
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 10:37 am

planewasted wrote:
Autonomous systems connected to flight controls should of course not act on bad sensor data. How can you argue against that? But it can happen anyway. No design is perfect, so pilots should be prepared to handle such events.

Turkish Airlines Flight 1951 crashed because of a bad sensor setting the engines to idle power and the pilots not noticing. A bit similar to this tragic crash.


Just as a general note, it's a vicious circle this human vs automation. Automation has been developed over decades to protect the airplanes from human error. And now pilots are being trained more and more to do exactly the right thing in case of a system error. Has automation maybe gone too far already? Now it's not enough for the pilots to fly the plane anymore in extreme situations - they have to be able to predict how the automated systems might set traps for them, and then maneuver around that. If they make a mistake or don't notice some tiny detail somewhere that the system secretly did, there's a risk that everyone onboard a perfectly healthy and capable aircraft will suffer a horribly violent death.

Nice. :thumbsup:
 
jeffrey0032j
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 10:41 am

BREECH wrote:
Starlionblue wrote:
You have a point. However pilot training is designed to repeatedly expose you to critical scenarios. The more likely and critical, the more often you see it.

Procedures are also designed so that memory items are kept to a minimum. Stabilise the aircraft, then reference a printed or on screen procedure. We are taught methods of dealing with situations, and we practice applying these methods.

The logic is that if you get something you’ve never seen you can used your knowledge and your methods to deal with it.

My point was slightly different. I'm not suggesting more or less of training. I'm suggesting more rigorous approach to designing airplanes. Maybe more thorough testing. Maybe something else, I don't know. How about putting a computer in the simulator and let them have a go at each other. I have no idea if that's even possible. What I'm trying to say is that way too many recent accidents were caused by some sort of a design flaw that was identified and the airlines may have even received "the fix" but either its implementation was postponed for some reason or the pilots didn't get the necessary training.

For example, with this Lion Air crash, WHY aren't all 737 max grounded until everything is fixed? Mind you, the manufacturer doesn't even deny that there is a problem (and THAT's a huge surprise considering the current McDonnell-Douglas corporate culture) but the FAA again follows the "promote aviation" part of their duties rather than the "control" part. How many more crashes do we need for FAA to finally be stripped of its duties as the control agency and those being transferred to NTSB?

I remember a very good film "Fight Club". Remember the scene on an airplane where the protagonist explains how car recalls work?
A new car built by my company leaves somewhere traveling at 60 mph. The rear differential locks up. The car crashes and burns with everyone trapped inside. Now, should we initiate a recall? Take the number of vehicles in the field, A, multiply by the probable rate of failure, B, multiply by the average out-of-court settlement, C. A times B times C equals X. If X is less than the cost of a recall, we don't do one.

And when asked which car company he works for, he answers, "A major one".

WHY do I have a feeling that this is exactly what's happening with Boeing? Boeing knows about their planes' defects, yet they apply the math. A certain number of crashes will mean certain financial consequences. And if those consequences are "less than X", they don't care.

In a similar vein, why weren't all A330s grounded back in 2008 when the computers on QF72 decided to plunge the plane twice, with absolutely no checklist for the flight crew to refer to (unlike the 737 Max which has an existing procedure to deal with it), and leaving the captain having a distrust with automation. The only lucky thing was that it happened during cruise, although the pilots had thought of the possibility of it happening closer to ground during their emergency landing.

While investigations have found that it was an error in the ADIRU in the A330s, they have never found out and therefore never fixed the root cause of the error. Airbus only did a work around after the incident to stop the issue from affecting flight.
 
rheinwaldner
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 11:02 am

osiris30 wrote:
rheinwaldner wrote:
Then why does Boeing send a bulletin only to the MAX operators?


As a reminder. The bulletin literally said follow established procedures. You know so more people don't die. It is pretty standard after a crash for reminder bulletins to be sent. It is a "hey guys.. remember this thing... seems like you may have forgotten it... so remember it"

You missed the point. The question was not why Boeing sent a bulletin. The question was, why the bulletin was sent only to the MAX operators (if the MAX would work the same as the earlier models, as claimed).

The answer was given in between: the MAX does not work the same.
Many things are difficult, all things are possible!
 
dirk88
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 11:46 am

Based on what's known about this accident by now, would people suggest avoiding Lion Air or would that be irrational? I need to fly domestically within Indonesia next week, and Lion has the most convenient option... allthough there are more expensive alternatives.
 
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zeke
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 12:18 pm

dirk88 wrote:
Based on what's known about this accident by now, would people suggest avoiding Lion Air or would that be irrational?


In my view that is correct, based upon one accident without evidence it has a systemic cause I would think it is irrational.

However my own personal view is that I would not fly with them even before the date of the accident, that is not based just on the previous incidents, it is by my personal observations on how they operate For example if I had a taxi clearance on a parallel taxiway to go to the holding point and one of their aircraft was asked to hold short of the parallel, a few times now I have cut off by one of them, ATC gave them the instruction a number of times to hold short, and their radio only seemed to work after they managed to jump the queue. Little things like that to another professional pilot does not instil confidence.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
rj777
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 12:34 pm

Any updates on the search for the CVR? They should've found it by now
 
mandala499
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 12:42 pm

Noshow wrote:
It's not acceptable anymore that recorded data cannot be retrieved easier because the storage hardware gets lost. Why not constantly radio them to some neutral place?

It's only been a week and people are talking like it has been years... Geez...
Anyway, wanna send the recorded data? How much data do you want to send? How many variables? How often?
Because that determines how much it's going to cost...

planewasted wrote:
Autonomous systems connected to flight controls should of course not act on bad sensor data. How can you argue against that? But it can happen anyway. No design is perfect, so pilots should be prepared to handle such events.

Turkish Airlines Flight 1951 crashed because of a bad sensor setting the engines to idle power and the pilots not noticing. A bit similar to this tragic crash.

I think there needs to be a way to switch a bad ADR off so it doesn't go and make other systems go drunk on it's toxic data. Bigger Boeings and the Airbii can switch off a bad ADR... either through a switch or the system kicks it off the network (figuratively speaking)... I think the same capability is required on the 737NG and Max.

dirk88 wrote:
would people suggest avoiding Lion Air or would that be irrational?

I avoid Lion Air because their passengers are so damn scary... I fly with Batik instead, also a member of the LionAir group...

rj777 wrote:
Any updates on the search for the CVR? They should've found it by now

Still searching for it. I suspect it is buried in the sand and mud below the main cluster of debris... that'll take time to get it...
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
dragon6172
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 1:16 pm

mandala499 wrote:
Pilots know runaway stab trim and the procedures...
Pilots know flight with unreliable airspeed and the procedures...
But how many until yesterday, know how to deal with both unreliable airspeed and runaway stab trim at the same time.
And let's not assume it's day VMC at the crash location just because it's day VMC at CGK airport...
It's all very nice for us to criticize the crew, or the manufacturer... because hindsight is always 20/20, especially when we're sitting on our comfy chairs with air conditioning...


maint123 wrote:
Importantly how is the auto trimming implemented in the Max series. If auto trimming commands of up to 5 to 10 secs are being given , this flight would have no hope of recovering. Pilot I hope would have the authority to switch off this auto trimming feature , but in this particular flight time available would be critical.


Even without complying with the runaway stab trim procedure to disconnect the "auto trimming", pilots will always have the ability to over-ride it. If the computer is trimming the aircraft nose down, simply pulling back on the control column stops the trimming. Using the trim switch on the the pilots yoke also will stop the computer controlled trimming. In other words, if the pilot is hand flying it isn't an issue. Either you are holding the aircraft level by keeping back pressure on the control column with a slightly out of trim aircraft, or you are constantly using the control yoke trim switches to trim the opposite direction.

Now, if you take your hands off the controls, don't notice the trim wheel spinning, don't notice the nose of the aircraft starting to point towards the ground (either outside or on the attitude indicator), then you forgot to aviate.

However, since they flew along mostly level at 5000 feet for 7 minutes it would seem to me they were dealing with the issue fairly well. Then they just took their hand off the controls? That doesn't make sense, so I feel like there is some more info to come out.
Phrogs Phorever
 
Amiga500
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 1:26 pm

Starlionblue wrote:
BUSS is quite simple actually. It uses raw AoA from the vanes. There is no speed displayed, just an AoA range. Just keep it in the green. Combine with an appropriate thrust setting and you get expected performance.


Excellent - my question is then - why do the pilots have to deactivate a load of primary instruments to get this information?

You'd think it should be displayed as primary info.
 
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BaconButty
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 1:44 pm

osiris30 wrote:
As a reminder. The bulletin literally said follow established procedures. You know so more people don't die. It is pretty standard after a crash for reminder bulletins to be sent. It is a "hey guys.. remember this thing... seems like you may have forgotten it... so remember it"


You clearly didn't read the AD then. For avoidance of doubt:
This AD requires revising ... operating procedures of the airplane
flight manual (AFM) to provide the flight crew with runaway horizontal stabilizer trim procedures to
follow under certain conditions


This isn't a case of RTFM, it's a case of changing the FM.
Down with that sort of thing!
 
Flightsimboy
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 2:03 pm

osiris30 wrote:


WOW. Just wow. RTFM. Also read the Lehman article. You have NO idea what you are talking about and are looking to grind an axe. This is one of the worst posts I have ever read on this forum. Your own post isn't self consistent. You claim Boeing is cryptic... they are not... at all. You claim to want to wait for data but in the SAME numbered point argue against the two statistically most likely sources of the issue and the ones most backed by data thus far into the investigation.

I pray to God you are never on a jury.


I hope you can keep these people in mind

https://goo.gl/images/arFwMc
 
dragon6172
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 2:21 pm

BaconButty wrote:
osiris30 wrote:
As a reminder. The bulletin literally said follow established procedures. You know so more people don't die. It is pretty standard after a crash for reminder bulletins to be sent. It is a "hey guys.. remember this thing... seems like you may have forgotten it... so remember it"


You clearly didn't read the AD then. For avoidance of doubt:
This AD requires revising ... operating procedures of the airplane
flight manual (AFM) to provide the flight crew with runaway horizontal stabilizer trim procedures to
follow under certain conditions


This isn't a case of RTFM, it's a case of changing the FM.

You forgot to italicize "under certain conditions". Runaway stab procedures were already in the FM, so yes it's still RTFM. All the AD says is if you have runaway stab combined with these other things, you must do the runaway stab procedures.

Now why wouldn't you do the runaway stab procedures anyhow? Does the aircraft manufacturer have to include every fault combination possible in the FM?
Phrogs Phorever
 
zakelwe
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 2:29 pm

As an aside BBC reported a human v control computer issue here just by chance

https://www.bbc.co.uk/news/uk-46137445

"The plane climbed to 1,500ft, but then pitched and "descended rapidly" because the autopilot was set with a target altitude of 0ft."

Pilot went manual and then sorted out. Happy outcome.

Some random musings follow.....

Until planes go fully automated it seems like more and more complex algorithms will compete with humans command of getting the button presses right and even if things done perfectly having to know a mass of manual material to sort out even if it does so whilst not being in the calm of a simulator or training room.

Iain M Banks wrote a sci fi novel called Excession which was about an outside context problem, something which occurs completely out of the blue and not expected. I wonder if pilots are getting more and more subjected to this due to modern day electronics and they not knowing the programmers logic and have too little time to work it all out? Or even if they have been taught the solution months back in school it becomes at that moment, with lights and sounds and pressure to sort it out, something known then becomes an outside context problem?

People sitting on armchairs luckily do not ever suffer from outside context problems when diagnosing, neither do the crash investigators.
 
hivue
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 2:50 pm

mandala499 wrote:
Pilots know runaway stab trim and the procedures...
Pilots know flight with unreliable airspeed and the procedures...
But how many until yesterday, know how to deal with both unreliable airspeed and runaway stab trim at the same time.


Can someone define precisely "runaway stabilizer trim?" mandala499 seems to be implying the possibility of dual, unrelated failures: (1) an unreliable airspeed issue of some sort and {2} a coincidental runaway stab trim. But I think others are saying that the airplane's trimming nose down in response to an excessive AoA indication -- which would be the expected and likely desired behavior if the AoA information were not erroneous -- actually represents a case of runaway stab trim.
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hinckley
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 3:23 pm

planewasted wrote:
Autonomous systems connected to flight controls should of course not act on bad sensor data. How can you argue against that? But it can happen anyway. No design is perfect, so pilots should be prepared to handle such events. Turkish Airlines Flight 1951 crashed because of a bad sensor setting the engines to idle power and the pilots not noticing. A bit similar to this tragic crash.


imo, this is precisely the biggest issue that civil aviation is facing today. I'm positive that airliner automation has saved, and will continue to save, thousands of lives. But every automated system has some sort of fault at some point in time, and a pilot's reaction to those faults can literally be the difference between life or death (see AF447). But as automation continues to improve, and fewer instances of faults in those systems occur, then even the best pilots will need more and more time to react to and compensate for those faults. It's a basic problem in any man-machine interface. Self-driving cars are at the cusp of experiencing this exact same thing.

There will always be huge grey areas. AF447 had both the time and the experienced pilots in the cockpit to compensate for malfunctioning pitot tubes. To me, the fault in that crash mainly lies with those pilots. But I wouldn't feel the same way if AF447 was flying at 2000 feet instead of 36000 feet. But what was enough time/altitude? 10000 feet? 20000 feet?

Of course all of us here on a.net are here to discuss (and speculate) about these issues. But it took two years before we fully understood what happened over the Atlantic on that AF flight. With Lion Air, we may find that there were MX issues which were botched. We may find that the pilots were incompetent to deal with the situation. Or we may find that they were completely competent and simply did not have the time to diagnose, react to, and rectify the situation that they were faced with. So let's discuss. Let's speculate. But it's waaay too early to assign blame.
 
Trin
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 3:59 pm

Knowing what we know so far about this incident - the following seems to me to be the events that should be receiving our focus, and in this order:

1. WHY did this MAX have faulty AoA sensors (and/or faulty airspeed sensors);
(Answer will lead to a possible hardware check/improvement on all MAXs)
2. WHY did the maintenance ground crews fail to remedy the faulty sensors at several opportunities between the last four flights of this aircraft;
(Answer will lead to possible disciplinary action and/or retraining/re-certification of maintenance ground crews)
And
3. WHY did the flight crew on this aircraft's last flight struggle with (and ultimately fail) to control the plane on this flight, in particular while up to three previous Lion Air flight crews encountered and successfully mitigated the issues during the flight phase of each of the four last legs undertaken by this hardware.
(Answer COULD possibly lead to retraining of Lion Air's flight crews)

I can't stress enough that order, either. This is NOT AF447. That much is at least becoming clear. This was not a standard flight configuration/situation that pilots are trained for from the beginning of their careers. There WAS something wrong with the aircraft, and it had persisted over several days despite multiple attempts to rectify it, apparently. Finally, I would quote the AD:

We are issuing this AD because we evaluated all the relevant information and determined the
unsafe condition described previously
is likely to exist or develop in other products of the same type
design. Due to the need to correct an urgent safety of flight situation, good cause exists to make this
AD effective in less than 30 days.


To me, that says that the issues that precipitated this tragic event (be they hardware related, software related, flight crew related or man-machine-interface related) are deemed to PROBABLY exist (or develop) in all other MAXs. To me, that constitutes a pretty urgent and glaring issue with these types until a hardware fix/AFM revision is issued.

So sad.

Trin
 
BREECH
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 4:41 pm

jeffrey0032j wrote:
In a similar vein, why weren't all A330s grounded back in 2008 when the computers on QF72 decided to plunge the plane twice, with absolutely no checklist for the flight crew to refer to (unlike the 737 Max which has an existing procedure to deal with it), and leaving the captain having a distrust with automation. The only lucky thing was that it happened during cruise, although the pilots had thought of the possibility of it happening closer to ground during their emergency landing.

While investigations have found that it was an error in the ADIRU in the A330s, they have never found out and therefore never fixed the root cause of the error. Airbus only did a work around after the incident to stop the issue from affecting flight.

Exactly! And while the fact that nobody died does make a huge difference, I agree with the underlying principle. If it's broke - FIX IT.
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PW100
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 4:41 pm

Trin wrote:
2. WHY did the maintenance ground crews fail to remedy the faulty sensors at several opportunities between the last four flights of this aircraft;
(Answer will lead to possible disciplinary action and/or retraining/re-certification of maintenance ground crews)

Alternative Answer: re-writing of the aircraft manual, trouble shooting sections, and follow-on maintenance procedures after combination of certain failures/errors.

Trin wrote:
3. WHY did the flight crew on this aircraft's last flight struggle with (and ultimately fail) to control the plane on this flight, in particular while up to three previous Lion Air flight crews encountered and successfully mitigated the issues during the flight phase of each of the four last legs undertaken by this hardware.
(Answer COULD possibly lead to retraining of Lion Air's flight crews)

Alternative Answer: re-writing of aircraft operating handbook, troubleshooting sections, and new memory items to handle specific combination of certain failures/errors.
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trpmb6
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 5:38 pm

per avherald:

On Nov 8th 2018 the KNKT reported an angle of attack sensor had been replaced on Oct 28th 2018 following the flight JT-775 from Manado to Denpasar (the aircraft completed the subsequent flight JT-43 to Jakarta and suffered the crash the next flight JT-610). The aircraft subsequently flew to Jakarta, the crew however reported there were still problems. The search for the CVR is hampered by thick mud.
 
michi
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 6:11 pm

Amiga500 wrote:
Starlionblue wrote:
BUSS is quite simple actually. It uses raw AoA from the vanes. There is no speed displayed, just an AoA range. Just keep it in the green. Combine with an appropriate thrust setting and you get expected performance.


Excellent - my question is then - why do the pilots have to deactivate a load of primary instruments to get this information?

You'd think it should be displayed as primary info.


AoA vanes are also prone to unreliable data. A vane might bend if you have a birdstrike directly onto it. Then, when using AoA a primary info, you still need to realise, that something is wrong. This circles back to the biggest challenge that comes with unreliable data: the recognition that you actually have unreliable air data. Here only pitch and power will help stabilising the flight path. When this is done, you should troubleshoot and try to find out, which air data (including AoA) is ok and which is unreliable.
This is not easy, as unreliable air data sometimes does not look unreliable. Blocked pitot tubes will lead to changing speed information on the PFD, when changing altitude. You might end up at an altitude, where all IAS speeds are the same, but still, some are unreliable. By the way, computers will fail to identify the unreliable source (s) in that case.

I have had crews in the simulator that recognised having unreliable air data. They stabilised and flew pitch and power till landing, as all the values where so inconsistent and ambiguous, that they where not able to tell which air data was correct and which not. The combination of failures they had where not that realistic, but still, they had one system, which was not affected at all. They realised, that this one system might be correct, but they where not 100% certain and elected to disregard it.

BUSS is nice. But for me it is more like an instrument, where I can check the correctness of my pitch and power values. BUSS respective AoA is load factor dependent. When you do a turn and pull some more g-force than normal, you will end up in the red area of the BUSS. Therefore, even with BUSS, I fly primarily Pitch and Power. I also will not use more than 15° of bank, as this helps with the g-force issue. Also I will try to do everything regarding airplane control and configuration sequentially. This makes flying with BUSS much easier. So, BUSS is not the holy grail, but it is a very nice tool!

Unreliable air data is complex. Even computers fail to recognise certain failure conditions. I have read suggestions upstream of the thread, that computers should compare all IAS values. And as soon as one IAS differs from the other 2, this value should be rejected by the computer. But what if the rejected value was the reliable one and the other 2 have been unreliable together (e.g.taped static ports)? These problems are known to the industry. Does the industry have solutions? Some are available: BUSS or the A350 use of FADEC data for a speed indication. Still there is no holy grail fighting unreliable air data. Pitch and power is still the best and easiest method for pilots. In the sim the pilots fly the regular approach speed ± 2knots using pitch and power. This is good enough!
 
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Erebus
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 6:31 pm

michi wrote:
But what if the rejected value was the reliable one and the other 2 have been unreliable together (e.g.taped static ports)? These problems are known to the industry.


I believe something similar happened in the XL Airways A320 crash during a test flight. 2 out of the 3 AoA sensors became stuck frozen at a particular value due to incorrect maintenance procedures but the computer disregarded the one correct sensor and used the other two erroneous ones causing the in-flight upsets.
 
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7BOEING7
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 7:20 pm

Erebus wrote:
michi wrote:
But what if the rejected value was the reliable one and the other 2 have been unreliable together (e.g.taped static ports)? These problems are known to the industry.


I believe something similar happened in the XL Airways A320 crash during a test flight. 2 out of the 3 AoA sensors became stuck frozen at a particular value due to incorrect maintenance procedures but the computer disregarded the one correct sensor and used the other two erroneous ones causing the in-flight upsets.


If the sensors were not frozen the crash wouldn't have happened, however, the pilots were 1) Not really qualified to do what they were doing, 2) Did the test below a generally excepted minimum altitude and 3) Had not determined a minimum speed at which to terminate the test -- if any one of those boxes were checked the crash would also have been prevented -- breaking a link in the chain of events.
 
Trin
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 7:25 pm

michi wrote:

AoA vanes are also prone to unreliable data. A vane might bend if you have a birdstrike directly onto it. Then, when using AoA a primary info, you still need to realise, that something is wrong. This circles back to the biggest challenge that comes with unreliable data: the recognition that you actually have unreliable air data. Here only pitch and power will help stabilising the flight path. When this is done, you should troubleshoot and try to find out, which air data (including AoA) is ok and which is unreliable.
This is not easy, as unreliable air data sometimes does not look unreliable. Blocked pitot tubes will lead to changing speed information on the PFD, when changing altitude. You might end up at an altitude, where all IAS speeds are the same, but still, some are unreliable. By the way, computers will fail to identify the unreliable source (s) in that case.

I have had crews in the simulator that recognised having unreliable air data. They stabilised and flew pitch and power till landing, as all the values where so inconsistent and ambiguous, that they where not able to tell which air data was correct and which not. The combination of failures they had where not that realistic, but still, they had one system, which was not affected at all. They realised, that this one system might be correct, but they where not 100% certain and elected to disregard it.

BUSS is nice. But for me it is more like an instrument, where I can check the correctness of my pitch and power values. BUSS respective AoA is load factor dependent. When you do a turn and pull some more g-force than normal, you will end up in the red area of the BUSS. Therefore, even with BUSS, I fly primarily Pitch and Power. I also will not use more than 15° of bank, as this helps with the g-force issue. Also I will try to do everything regarding airplane control and configuration sequentially. This makes flying with BUSS much easier. So, BUSS is not the holy grail, but it is a very nice tool!

Unreliable air data is complex. Even computers fail to recognise certain failure conditions. I have read suggestions upstream of the thread, that computers should compare all IAS values. And as soon as one IAS differs from the other 2, this value should be rejected by the computer. But what if the rejected value was the reliable one and the other 2 have been unreliable together (e.g.taped static ports)? These problems are known to the industry. Does the industry have solutions? Some are available: BUSS or the A350 use of FADEC data for a speed indication. Still there is no holy grail fighting unreliable air data. Pitch and power is still the best and easiest method for pilots. In the sim the pilots fly the regular approach speed ± 2knots using pitch and power. This is good enough!


I just wanted to say thanks for a great post and for laying out and explaining some of the inherent difficulties in flying these large jets and reliance (or lack thereof) upon the air data information/sensors. It does help a lot of us who are not from backgrounds in aviation to understand the WHYS when something like this happens, and also see that the matter is invariably more complicated than we are aware.

I would really be interested to be able to experience sitting in a sim and trying to deal with some of the possible scenarios that pilots are trained for. I imagine it is next to impossible to train for every single unlikely scenario, and what pilots do on a daily basis still amazes me to no end.

Trin
 
osiris30
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 9:03 pm

Finn350 wrote:
osiris30 wrote:
Finn350 wrote:

I would assume a program change concerning trim automation in certain malfunctions.


It is possible but I believe the current mode of operation was induced due to regulatory reasons. It is more likely IMHO the existing procedures will be found to be adequate and that training or crm caused the crash.


I am sure that the FAR doesn't require an aircraft to nosedive without pilot action in any situation. The longitudinal stability requirements can surely be fulfilled in other, less dangerous ways.


I am sure the aircraft didn't nose dive on its own. The trim system (as I understand it) doesn't have enough authority to accomplish that IF the pilots are flying the aircraft.
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
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PW100
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 9:52 pm

osiris30 wrote:
I am sure the aircraft didn't nose dive on its own. The trim system (as I understand it) doesn't have enough authority to accomplish that IF the pilots are flying the aircraft.


Not sure if I follow this: STS commands (limited) nose down, pilots not counteract sufficiently (for whatever reason were not pulling up immediately - perhaps because of stall warning/stick shaker?), but you are sure the aircraft did not dive on its own? It seems that's what you just described.
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CO953
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Thu Nov 08, 2018 11:06 pm

Trin wrote:
michi wrote:



I would really be interested to be able to experience sitting in a sim and trying to deal with some of the possible scenarios that pilots are trained for. I imagine it is next to impossible to train for every single unlikely scenario, and what pilots do on a daily basis still amazes me to no end.

Trin


I would be interested to see (pie-in-the-sky idea, I admit), simulators be programmed with the failure parameters of every major crash of that aircraft type (as long as the applicable systems were still in service on aircraft being flown in modern fleets), and them randomly throw two or three of these famous accidents into each training/certification session. Make it almost like mental flash cards for the pilots, to try to recover from a various of fatal accidents, so as to build in some muscle memory....
 
osiris30
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Fri Nov 09, 2018 12:37 am

PW100 wrote:
osiris30 wrote:
I am sure the aircraft didn't nose dive on its own. The trim system (as I understand it) doesn't have enough authority to accomplish that IF the pilots are flying the aircraft.


Not sure if I follow this: STS commands (limited) nose down, pilots not counteract sufficiently (for whatever reason were not pulling up immediately - perhaps because of stall warning/stick shaker?), but you are sure the aircraft did not dive on its own? It seems that's what you just described.


If you look at the flight graphs the auto trim didn't command the (fatal) nose down. It wad far too fast and sudden of a dive for the trim system to be solely responsible. Trim adjusts slowly over seconds and within limits. Given a known delta of 20 degrees max error in the aoa the trim would have obly commanded 20deg nose down max (likely 18.5 or so). The final seconds of the flight were MUCH steeper than that.

The trim system is not what flew this plane into the ground.
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
salttee
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Fri Nov 09, 2018 1:03 am

mandala499 wrote:
Pilots know runaway stab trim and the procedures...
Pilots know flight with unreliable airspeed and the procedures.
But how many until yesterday, know how to deal with both unreliable airspeed and runaway stab trim at the same time.
I don't see it that way. How many pilots don't know to pull back on the yoke if the plane they are flying starts nosing down? How many pilots have died because they were too eager to pull back when their plane appeared to be heading toward the ground? We are told (by the fishermen) that this plane went into a steep dive and apparently never attempted to pull out.

I don't see how that could be the result of a gradual application of elevator trim.
mandala499 wrote:
let's not assume it's day VMC at the crash location just because it's day VMC at CGK airport..
That suggestion if true would throw this whole analysis so far (by everyone) into the trash can: I don't see how that could be the case and yet never have been mentioned by anyone from Soekarno-Hatta Airport.

dragon6172 wrote:
Even without complying with the runaway stab trim procedure to disconnect the "auto trimming", pilots will always have the ability to over-ride it. If the computer is trimming the aircraft nose down, simply pulling back on the control column stops the trimming. Using the trim switch on the the pilots yoke also will stop the computer controlled trimming. In other words, if the pilot is hand flying it isn't an issue. Either you are holding the aircraft level by keeping back pressure on the control column with a slightly out of trim aircraft, or you are constantly using the control yoke trim switches to trim the opposite direction.

Now, if you take your hands off the controls, don't notice the trim wheel spinning, don't notice the nose of the aircraft starting to point towards the ground (either outside or on the attitude indicator), then you forgot to aviate.

However, since they flew along mostly level at 5000 feet for 7 minutes it would seem to me they were dealing with the issue fairly well. Then they just took their hand off the controls? That doesn't make sense, so I feel like there is some more info to come out.
It doesn't make sense to me either. I believe that people have jumped on this AOA tidbit of information a bit too eagerly.
 
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Starlionblue
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Fri Nov 09, 2018 2:29 am

michi wrote:
Amiga500 wrote:
Starlionblue wrote:
BUSS is quite simple actually. It uses raw AoA from the vanes. There is no speed displayed, just an AoA range. Just keep it in the green. Combine with an appropriate thrust setting and you get expected performance.


Excellent - my question is then - why do the pilots have to deactivate a load of primary instruments to get this information?

You'd think it should be displayed as primary info.


AoA vanes are also prone to unreliable data. A vane might bend if you have a birdstrike directly onto it. Then, when using AoA a primary info, you still need to realise, that something is wrong. This circles back to the biggest challenge that comes with unreliable data: the recognition that you actually have unreliable air data. Here only pitch and power will help stabilising the flight path. When this is done, you should troubleshoot and try to find out, which air data (including AoA) is ok and which is unreliable.
This is not easy, as unreliable air data sometimes does not look unreliable. Blocked pitot tubes will lead to changing speed information on the PFD, when changing altitude. You might end up at an altitude, where all IAS speeds are the same, but still, some are unreliable. By the way, computers will fail to identify the unreliable source (s) in that case.

I have had crews in the simulator that recognised having unreliable air data. They stabilised and flew pitch and power till landing, as all the values where so inconsistent and ambiguous, that they where not able to tell which air data was correct and which not. The combination of failures they had where not that realistic, but still, they had one system, which was not affected at all. They realised, that this one system might be correct, but they where not 100% certain and elected to disregard it.

BUSS is nice. But for me it is more like an instrument, where I can check the correctness of my pitch and power values. BUSS respective AoA is load factor dependent. When you do a turn and pull some more g-force than normal, you will end up in the red area of the BUSS. Therefore, even with BUSS, I fly primarily Pitch and Power. I also will not use more than 15° of bank, as this helps with the g-force issue. Also I will try to do everything regarding airplane control and configuration sequentially. This makes flying with BUSS much easier. So, BUSS is not the holy grail, but it is a very nice tool!

Unreliable air data is complex. Even computers fail to recognise certain failure conditions. I have read suggestions upstream of the thread, that computers should compare all IAS values. And as soon as one IAS differs from the other 2, this value should be rejected by the computer. But what if the rejected value was the reliable one and the other 2 have been unreliable together (e.g.taped static ports)? These problems are known to the industry. Does the industry have solutions? Some are available: BUSS or the A350 use of FADEC data for a speed indication. Still there is no holy grail fighting unreliable air data. Pitch and power is still the best and easiest method for pilots. In the sim the pilots fly the regular approach speed ± 2knots using pitch and power. This is good enough!


:checkmark: :checkmark: :checkmark:

Excellent post. This should be required reading before any discussion about airspeed instrumentation.
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