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Indonesian aircraft missing off Jakarta

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Indonesian aircraft missing off Jakarta

Old 4th Nov 2018, 17:30
  #581 (permalink)  
 
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Yep

I vote for airline disingenuous.
But it sure is troubling to think that the FC w engineer, presumably fully briefed on/even anticipating a particular problem, were still overcome. Assuming the issue was the same as prior flight of course.
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Old 4th Nov 2018, 17:37
  #582 (permalink)  
 
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Originally Posted by A Squared View Post
Well, one of the lines of speculation is that the handling problems were exacerbated by the computer control of an automated trim system, as a result of erroneous data being fed into the computer.
The term Ďcomputerí is somewhat overstating the technology in the speed-trim system. It is a couple of 286 processors, based upon a Sinclair ZX Spectrum architecture.

Silver
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Old 4th Nov 2018, 18:19
  #583 (permalink)  
 
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To me this all boils down to a very simple set of questions. We have an airframe with a known set of technical issues which were easily managed on the previous flight. Those known issues should have generated a very specific review of certain procedures and been addressed in detail in the preflight planning/brief.

So...

1) were the memory items and checklist briefed prior to takeoff as would be expected?
2) was the problem identified in a timely manner and were the memory items and checklist preformed in a timely manner?
We MUST assume that :
a)the accident crew were aware of the previous flights UAS because it was written up in the tech log and would prohibit that Commanders acceptance of the
aircraft unless it had been signed off by a licensed engineer.When the accident Captain signs for the aircraft,he acknowledges reading the write up by the previous commander and the corrective action taken by the engineer.He must do this to accept the aircraft.

We CAN REASONABLY assume that:
a)The accident crew would have given special attention to UAS during the pre-flight briefing.They would have reviewed memory items and/or a plan of action.
b)The accident crew would have tried to obtain first hand information from the previous crew if possible(phone)
c)The flying spanner was added to the accident crew because of the tech issue.Lionair is a big airline and will have engineers based at most destinations.
d)The accident crew would have discussed the absolute need NOT to take a known pitot static anomaly into the air,of the need to abort the takeoff if ASIs diasgree at 80 knots.
e)The fact that they did not abort the takeoff implies strongly that the UAS was undiscoverable on takeoff.Prime suspect static vent(s).

We CAN HOPEFULLY assume:
a)Both accident crew members had been trained in UAS events in the simulator on one or more occasions in their flying career.
b)that both crew members knew verbatim the UAS memory items and of the absolute need to disengage ALL AUTOMATION and recognize that there is a mismatch between reality and perception and fly the plane using common sense attitude/thrust combinations.
c)That the crew would have sufficient lateral thinking to disengage any system fed by ADIRU false data that might conflict with their ability to control the aircraft.eg STS.The pilots see/hear the trim wheel spinning.They know or should know it is fed via AP stab trim motor.They know where the AP stab trim cutout switch is.

We can NEVER assume:
a)that the startle effect in all non normal situations will be controlled and handled well by a crew.The longer the startle effect lasts the more chance for loss of muscle memory,cognitive thinking,and onset of panic.
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Old 4th Nov 2018, 18:33
  #584 (permalink)  
 
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Originally Posted by Rananim View Post
We MUST assume that :
a)the accident crew were aware of the previous flights UAS because it was written up in the tech log and would prohibit that Commanders acceptance of the
aircraft unless it had been signed off by a licensed engineer.When the accident Captain signs for the aircraft,he acknowledges reading the write up by the previous commander and the corrective action taken by the engineer.He must do this to accept the aircraft.
.
Not necessarily, it depends on the airline's rules for what exactly must be checked. For example, at mine, we have to look that all squawks are closed since the last airworthiness release. Some look back further than that, some don't. So if I see an airworthiness release from last night on a new (otherwise) blank page, I've satisfied my requirement without looking back to yesterday's squawk and corrective action.
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Old 4th Nov 2018, 19:26
  #585 (permalink)  
 
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A worrying inability to handle an air data non-normal in a "new" jet

I'm personally concerned that the CAA UK has signed off UK operators doing a bit of CBT at home and thats the end of any differences training. Training in the UK has reached rock bottom in terms of quantity and in many training events quality

Sad state of affairs
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Old 4th Nov 2018, 20:07
  #586 (permalink)  
 
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Originally Posted by Rananim View Post
We MUST assume that :
a)the accident crew were aware of the previous flights UAS because it was written up in the tech log and would prohibit that Commanders acceptance of the
aircraft unless it had been signed off by a licensed engineer.When the accident Captain signs for the aircraft,he acknowledges reading the write up by the previous commander and the corrective action taken by the engineer.He must do this to accept the aircraft.

We CAN REASONABLY assume that:
a)The accident crew would have given special attention to UAS during the pre-flight briefing.They would have reviewed memory items and/or a plan of action.
b)The accident crew would have tried to obtain first hand information from the previous crew if possible(phone)
c)The flying spanner was added to the accident crew because of the tech issue.Lionair is a big airline and will have engineers based at most destinations.
d)The accident crew would have discussed the absolute need NOT to take a known pitot static anomaly into the air,of the need to abort the takeoff if ASIs diasgree at 80 knots.
e)The fact that they did not abort the takeoff implies strongly that the UAS was undiscoverable on takeoff.Prime suspect static vent(s).

We CAN HOPEFULLY assume:
a)Both accident crew members had been trained in UAS events in the simulator on one or more occasions in their flying career.
b)that both crew members knew verbatim the UAS memory items and of the absolute need to disengage ALL AUTOMATION and recognize that there is a mismatch between reality and perception and fly the plane using common sense attitude/thrust combinations.
c)That the crew would have sufficient lateral thinking to disengage any system fed by ADIRU false data that might conflict with their ability to control the aircraft.eg STS.The pilots see/hear the trim wheel spinning.They know or should know it is fed via AP stab trim motor.They know where the AP stab trim cutout switch is.

We can NEVER assume:
a)that the startle effect in all non normal situations will be controlled and handled well by a crew.The longer the startle effect lasts the more chance for loss of muscle memory,cognitive thinking,and onset of panic.
So what do you think that the crews intent was once the UAS issue surfaced. Were they focused on returning to the field (level at 5k vs, gradual climb?) or did they intend to continue the flight as per the previous crew. Given the time lapse (roughly 5 minutes) at roughly 5000 feet without declaring an emergency I'd guess that the crew felt reasonably in control
of the situation. If they intended to continue why not maintain a gradual ascent like the previous flight? If in fact they had flight control issues (vs strictly UAS) why not declare an emergency? Is it possible that the engineer was in the jump seat and making trouble shooting recommendations or observations/requests? Would this create a distraction or complication that would lead to a sudden loss of control?

If the crew had never had a 3rd person involved in a sim setting is it a possibility that the unexpected distraction of that additional voice and potential trouble shooting interaction created enough confusion to lead to a sudden upset or undertake a course of action outside of the preflight brief? I'm wondering if the tech might have asked them to reengage the AP at some point for example?
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Old 4th Nov 2018, 20:19
  #587 (permalink)  
 
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Originally Posted by Machinbird View Post
From FR24 data, the aircraft was pretty much accelerating/overpowered throughout.
This is what intrigues me most. Overspeed is about the only consistent thing about the flight, at least from what can be ascertained so far from the "data".



Originally Posted by Machinbird View Post
If I was airborne and found out that I was now a test pilot, flying an aircraft that was not performing at all like it is supposed to, I would try to maintain the airspeed close to where I first found the problem, and then move cautiously toward the most forgiving portion of the flight envelope considering the current aircraft configuration.
Is it a stretch to imagine the airline in question "troubleshooting" an undetermined and assumed controllable anomaly in such a way?

Originally Posted by Machinbird View Post
Just my 2 cents from a steam gauge era viewpoint.
It is perhaps unfortunate in this instance that the crew did not have a few stone-age instruments onboard. (edit: at least instruments they paid any attention to) I often thank the almighty that the only things on my little crate that can even remotely be considered electronic are the lights and radios.
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Old 4th Nov 2018, 20:22
  #588 (permalink)  
 
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Originally Posted by Rananim View Post
We MUST assume that :
Ö
We CAN REASONABLY assume that:
...
We CAN HOPEFULLY assume:
Ö
I'm rather convinced that if all your assumptions had been fulfilled in this case we would not be having this Thread here.
And
We can NEVER assume:
a)that the startle effect in all non normal situations will be controlled and handled well by a crew.The longer the startle effect lasts the more chance for loss of muscle memory,cognitive thinking,and onset of panic
wouldn't have applied had they been sufficiently prepared mentally and training wiseÖ

This is assuming it wasn't a totally unrecoverable problem with the airframe (which I would consider extremely remote).
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Old 4th Nov 2018, 21:28
  #589 (permalink)  
 
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Salute!

Dat's right, Henra.
++++++++++++++++++++

Had to go back to the Alaska Airline crash with the " jackscrew nut. Wanted to see if there had been a squak on a preceding flight. Couldn't tell, but it would seem to me with all the damage that jackscrew had and the metal trapped in the big nut, that there would have been some slight indication to the PF. OTOH, with the use of the AP, the jammed stab was overcome by basic elevator trim. Finally, aero forces and commands by the PF caused the frst failure.
===================
Looking for a silver lining, this crash is a wakeup call to examine not only procedures but the design of the stab and pitch feel system, then all the air data inputs.

I tend to go with 'bird ( as in Machin') about possible PIO due to bad data coupled with a flaky pitch trim. You do not need a massive structural failure to reach extreme vertical pitch and speeds. We saw that at Rostov and that whole maneuver was done by the crew ( still have chills seeing the video). And one of our 73X drivers here claims that losing some or all of that trim/feel system can be challenging, especially at higher speeds.

And I have been a non volunteer test pilot on at least two flights, two types. Not fun. Only one required instant action and even that one I did the "don't just do something, sit there!" for first few seconds. Jet was still flying, so whatever I had was good enuf for then. picture on my PPRuNe profile bio.

Gums opines...
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Old 4th Nov 2018, 21:59
  #590 (permalink)  
 
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Originally Posted by JulioLS View Post
Nice idea but how does this computer know the pitch or AoA? ....

How?? There are AoA sensors.
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Old 4th Nov 2018, 22:03
  #591 (permalink)  
 
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Originally Posted by gums View Post
Had to go back to the Alaska Airline crash with the " jackscrew nut. Wanted to see if there had been a squak on a preceding flight. Couldn't tell, but it would seem to me with all the damage that jackscrew had and the metal trapped in the big nut, that there would have been some slight indication to the PF. OTOH, with the use of the AP, the jammed stab was overcome by basic elevator trim. Finally, aero forces and commands by the PF caused the frst failure.
Salute gums!
That was indeed a really harrowing accident. And one which was completely unrecoverable by the crew. I can't imagine a similar mechanical problem in an only 6 months old (read: brand new) 737 MAX, though, despite the fact that the final dive reminds indeed somewhat of Alaska 261.

Looking for a silver lining, this crash is a wakeup call to examine not only procedures but the design of the stab and pitch feel system, then all the air data inputs.

I tend to go with 'bird ( as in Machin') about possible PIO due to bad data coupled with a flaky pitch trim. You do not need a massive structural failure to reach extreme vertical pitch and speeds. We saw that at Rostov and that whole maneuver was done by the crew ( still have chills seeing the video). And one of our 73X drivers here claims that losing some or all of that trim/feel system can be challenging, especially at higher speeds.
A mis- behaviour of the STS / Elevator feel system as a result of an Air Data problem ist indeed probably quite high up the probability scale as a main culprit for this one. That said there should have been ways of stopping the interference of STS, e.g. by pulling the AP stab trim CB.
Still it might be worth having a second look if the systems cannot be made to act more benignly. UAS in itself is probably a challenge to a Crew and topping this with automatic mis- trimming due to bad air data is obviously not a terribly good idea and has led to accidents in the past. That is one area of flight safety where there might be a little room for improvement from an engineering perspective (although how to do it exactly will have to be very cautiously thought through - it is easy to create unwanted side effects in other cases when not done properly).

Regards,
Henra
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Old 4th Nov 2018, 22:05
  #592 (permalink)  
 
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Originally Posted by gums View Post
Had to go back to the Alaska Airline crash with the " jackscrew nut. Wanted to see if there had been a squak on a preceding flight. Couldn't tell, but it would seem to me with all the damage that jackscrew had and the metal trapped in the big nut, that there would have been some slight indication to the PF. OTOH, with the use of the AP, the jammed stab was overcome by basic elevator trim. Finally, aero forces and commands by the PF caused the frst failure.
The longitudinal trim control system had been working up to and including the initial phase of the accident flight.
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Old 4th Nov 2018, 23:41
  #593 (permalink)  
 
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A mis- behaviour of the STS / Elevator feel system as a result of an Air Data problem ist indeed probably quite high up the probability scale as a main culprit for this one.
Perhaps donít call it a mis-behavoir as itís doing what itís supposed to, based on the ASI inputs. Recognising and responding appropriately is the key.

Some of the first checklist items are to start switching things off.

Youíd be behind the 8-ball the whole time if this failed and if you tried to turn around before you were stabilised.

Can the input source be switched on the STS? (Iím assuming it could be)
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Old 5th Nov 2018, 00:40
  #594 (permalink)  
 
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You only have to look at that video of the wreckage, look at what is left of that engine (just the core), look at the shredded aircraft skin, read the reports that there seems to be no major piece of wreckage and of course that no victims remains are likely to be found intact, and you realise that this airplane from just few thousand feet hit the sea with such force that it was akin to flying into a mountain face or a building. Assuming MH370's final act was a similar nose dive into the ocean, but from a much higher altitude, is it any wonder nothing has been found? The engine cores of MH370 and some landing gear would fall to the bottom to be indistinguishable among rocks and detritus while the rest of the aircraft shredded into a million tiny pieces would slowly sift itself over hundreds of square miles of the Indian Ocean as these pieces drifted in the current and slowly descended the four miles to the bottom. Very much a case of "there's nothing to see here folks, go home".

But this Lion Air accident happened in only thirty metres of water. So I guess most of the remains will be concentrated but they may be buried in a similar way to the Value Jet crash that buried itself deep in a swamp. Like the Lion Air crash, the Value Jet aircraft ( loss of control due to fire in their case) was airborne for just 10 minutes before it rolled over and head down at 860km/h impacting with the swamp near vertically. The aircraft was destroyed on impact, with no large pieces of the fuselage remaining, and like Lion Air there were little in the way of intact human remains. I guess why I'm comparing these two is to understand just how difficult it may be to find or extract the CVR from the ocean bed. Although, the pinger going off is a really good sign that maybe the CVR is still above the sea bottom. The FDR presumably was and I assume that they are both co- located in the tail?
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Old 5th Nov 2018, 00:42
  #595 (permalink)  
 
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Could we have a similar situation to Air Asia 8501; ie inflight fault finding gone awry, a CB pulled at an inappropriate time?
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Old 5th Nov 2018, 00:58
  #596 (permalink)  
 
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Originally Posted by Lord Farringdon View Post
Assuming MH370's final act was a similar nose dive into the ocean, but from a much higher altitude, is it any wonder nothing has been found?
Bad assumption, large pieces of MH370 were found and in fairly good condition, whatever was found was not "shredded", so the current assumption is that MH370 hit water in a fairly benign fashion. Anyway, I would not mix both accidents, I would not draw any parallels, there is enough trolling in this thread already.
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Old 5th Nov 2018, 00:59
  #597 (permalink)  
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Re pitot pressures and pitot covers etc., pitot pressures for the elevator feel computer are sourced from individual pitot tubes located on either side of the vertical fin, (and not the pitots supplying data to the ADRs).

The static ports for inputs to the elevator feel computer are located on the lower left rear of the fuselage, (below/fwd of the horizontal stab). This is for the -400 series and may differ for the Max.

This may distinquish a unique "UAS" problem, (single failure, referenced generally in the thread), from any possible combined UAS / STS / Elevator feel problem, (ref D.Bru comments). The SSDFR and CVR information become critical to understanding.

Last edited by PJ2; 5th Nov 2018 at 06:41.
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Old 5th Nov 2018, 01:15
  #598 (permalink)  
 
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Originally Posted by olasek View Post
Bad assumption, large pieces of MH370 were found and in fairly good condition so the current assumption is that MH370 hit water in a fairly benign fashion. Anyway, I would not mix both accidents, I would not draw any parallels, there is enough trolling in this thread already.
Alright forget I mentioned 'that other' accident. My comment was most certainly not an attempt to troll but to sincerely understand the conditions in which the search for the CVR is being undertaken. I could refer to another one that had some really good deep sea diver experience commenting on the thread (but won't in case I'm told off again) but if we don't learn something from these past recovery attempts what is the point of even having this thread? We become limited in what we can discuss with that sort of community censorship.
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Old 5th Nov 2018, 02:27
  #599 (permalink)  
 
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It seems to me that the decision of the preceeding flight to continue to destination may have been quite properly made on safety grounds, they could have felt that they needed that transit time to become fully confident in controlling the craft in manual mode, they had an agreed flight plan and could plan ahead, It may well have taken them that length of flight to become confident that they could manover without entering PIO.
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Old 5th Nov 2018, 04:22
  #600 (permalink)  
 
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Trouble is these modern, highly automated and computerised jets are so simple to operate that most of the time a school kid can fly them.
But when the computers and automation get glitchy, they suddenly need a pilot, and a good one at that.
It seems that most of the time, that pilot is right there, and ready- but when he isn't, we get AF447 or any of the recent 'loss of control' type accidents.
Maybe the memory action for some of these system failures should be 'Automatics off. FLY. Do nothing for a while. Think'.
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