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Indonesian aircraft missing off Jakarta

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Indonesian aircraft missing off Jakarta

Old 2nd Nov 2018, 21:00
  #461 (permalink)  
 
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Re asking for Airspeed

...does that imply that the FC could not determine reliable airspeed from their 3 indicators....?
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Old 2nd Nov 2018, 21:32
  #462 (permalink)  
 
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Gold contacts on circuit boards

Originally Posted by AlexGG View Post
I wonder, considering there are not that many contacts, why aren't they made of gold or something which does not corrode? Sure that can't be overly expensive? That's assuming the recorder is built around memory chips (not tape or wire).
I believe gold is still subject to electrolytic corrosion. Salt water is a good conductor so two dissimilar metals become a battery and the current can erode both metals (this is why boats have 'zincs' attached to their hulls). Distilled water is a very poor conductor so it will prevent electrolytic corrosion.
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Old 2nd Nov 2018, 21:39
  #463 (permalink)  
 
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Originally Posted by flash8 View Post
In some cases would the QAR (assuming it has one, think it is an option) yield useful information (assuming also intact) and if the FDR were damaged or as a supplementary sources?
Unlikely that the QAR (or ONS server) would survive a high speed impact and subsequent extended immersion in salt water - they are simply not designed for it. FDR and CVR are very robust - particularly water (ref the AR 447 which spent 2 years 1000 feet down). Their greatest weakness is still fire - no matter how well insulated, if the fire is hot enough for long enough it'll get solid state memory components hot enough to be an issue - not an issue for this accident.
However the current generation of FDR contain a wealth of information - far beyond the minimum requirements of the regulations. The only real shortcoming of the FDR vs. the QAR or ONS is the update rate for some parameters (e.g. engine and FADEC stuff - once per second FDR, much higher update for QAR/ONS).
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Old 2nd Nov 2018, 22:06
  #464 (permalink)  
 
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Originally Posted by FullWings View Post
I find it interesting that the pilot asks for “airspeed” from ATC. Unless there was a EHS compatible transponder/receiver pair, then the answer is going to be groundspeed - which should be in the top left corner of the NAV display in front of him. It does seem to indicate that at least one of the problems they are facing is UAS...
I would think a brand new 737 MAX would have EHS capability. If so and if ATC did as well, maybe the 332 knot reading was indeed indicated airspeed and transmitted with the Mode S data.

However, based on previous news coverage of international accidents, often things get garbled in translation of ATC dialog in English to the local vernacular language and back to English again.

Has the claimed JT610 ATC transcript been published somewhere other than the gist given in the tempo.co article?

Originally Posted by tdracer View Post
Unlikely that the QAR (or ONS server) would survive a high speed impact and subsequent extended immersion in salt water - they are simply not designed for it.


Is it likely as the ABC News article suggests that significant data may be recovered from the Boeing servers back home from the ONS? Even twenty years ago I was surprised how much operational and maintenance information was spit out in the clear over VHF ACARS by so-called modern airliners. Engine readings, fluid levels, EFIS alerts, crew lists with employee numbers (and in some cases SSN's ) plus the usual mundane text messages to call the chief pilot's office on arrival.

Even if Lion Air didn't buy the upgraded subscription to Boeing's inflight data services, would some of the information be transmitted anyway?
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Old 2nd Nov 2018, 22:28
  #465 (permalink)  
 
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Originally Posted by Airbubba View Post
I would think a brand new 737 MAX would have EHS capability. If so and if ATC did as well, maybe the 332 knot reading was indeed indicated airspeed and transmitted with the Mode S data.
ATC may have actually been quoting groundspeed, which did reach 332 kt early in the flight (as well as later on).
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Old 2nd Nov 2018, 22:34
  #466 (permalink)  
 
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Unlikely that the QAR (or ONS server) would survive a high speed impact and subsequent extended immersion in salt water
True, but the data storage media would probably survive and the data be recoverable.
Or maybe not - there are a lot of variables.

I have known several business cases where data has been recovered from both flooded and fire damaged systems by specialist data recovery companies, they are very good at their job. If a fire gets into the server room the machines are usually wrecked and then drowned by the fire brigade but data is usually recoverable. Indeed, the opposite case of securely destroying sensitive data is very difficult and expensive.
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Old 2nd Nov 2018, 22:50
  #467 (permalink)  
 
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So, are we looking at a UAS event causing false inputs into the STS? This puts in a nose down trim, the pilots counteract with nose up elevator. Without any throttle reduction the aircraft accelerates to high speed until something snaps. As no other separate floating debris field has been found, and a near vertical dive, I suspect it was the stab trim screw jack that gave way at the end.
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Old 2nd Nov 2018, 22:53
  #468 (permalink)  
 
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Originally Posted by Airbubba View Post
I
Is it likely as the ABC News article suggests that significant data may be recovered from the Boeing servers back home from the ONS? Even twenty years ago I was surprised how much operational and maintenance information was spit out in the clear over VHF ACARS by so-called modern airliners. Engine readings, fluid levels, EFIS alerts, crew lists with employee numbers (and in some cases SSN's ) plus the usual mundane text messages to call the chief pilot's office on arrival.

Even if Lion Air didn't buy the upgraded subscription to Boeing's inflight data services, would some of the information be transmitted anyway?
The operator needs to sign up for the service - the hardware is baseline on the aircraft, but not the download service. Boeing (and GE/CFM) will store the data, but only if it gets sent -and that costs money. And the more data is sent out, the more it costs - shortly after the EIS of the 747-8, we started getting complains that we were sending out too much engine health data and it was costing too much for the data transmission services. So when we revised the EHM software we reduced the baseline reports.
Many operators only do downloads when they are at a suitably equipped (e.g. wifi) airport.
It's simply a matter of what Lion Air has signed up for (which I can't speak to - I honestly have no idea).
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Old 2nd Nov 2018, 23:00
  #469 (permalink)  
 
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Salute!

With all due respect, you can compare all the gauges and indicators with what you expect they should read and then add what the plane is doing that you do not expect, and then you have to take action or wait just second or two. 'Hal' will not be your friend. Unless in a 'bus, your plane most likely has traditional aerodynamic stability and power characteristics. You know. The thing tries to get back to your trim AoA, and pushing up power raises or lowers the nose, especially with motors below the wing. The 'bus has great aero, but it does not show itself until the flight control computers are back to the lowest possible functional capability. You never have complete manual control of that plane.

The 'bus is 100% +/- computer with tiny bit of manual reversion for something or other, but not significant. It has a myriad of reversion control laws, but at least you know you are dealing with a full FBW system.

The stab trim implementation on this beast seems to be a hybrid, and I am not sure what one should do if we have unreliable air data or maybe some hydraulic/electric malfunction involving the stab.

So we now have a plane with some type of "trim"/ speed stability feature that depends upon air data and weight on wheels and autopilot status and time after takeoff and so on. What does it do when the airdata is unreliable? How could it determine that? And what did it do a flight or two before if something mechanical is beginning to fail ( can't get Air Alaska outta my mind)?

The recorders should really help us see what happened from the human aspect as well as the mechanical/computer aspect and we can then improve the STS function and crew procedures, ya think?

Gums sends...
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Old 2nd Nov 2018, 23:13
  #470 (permalink)  
 
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ake this news report with a grain of salt . . . which indicates Indonesia’s transport ministry found faults in two other Boeing 737-MAX 8 jets, including a cockpit indicator display problem . . .

https://www.perthnow.com.au/travel/l...6c4a47f53d21e6
Could be minor engineering issues, could be a wider Boeing issue. Could be just trying to divert the blame game away from Lion in the short term.

If if it was a wider Boeing problem you would be looking at global groundings until rectified.
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Old 2nd Nov 2018, 23:20
  #471 (permalink)  
 
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Originally Posted by tdracer View Post
The operator needs to sign up for the service - the hardware is baseline on the aircraft, but not the download service. Boeing (and GE/CFM) will store the data, but only if it gets sent -and that costs money. And the more data is sent out, the more it costs - shortly after the EIS of the 747-8, we started getting complains that we were sending out too much engine health data and it was costing too much for the data transmission services. So when we revised the EHM software we reduced the baseline reports.
Many operators only do downloads when they are at a suitably equipped (e.g. wifi) airport.
It's simply a matter of what Lion Air has signed up for (which I can't speak to - I honestly have no idea).
If I were to try to guess which carrier(s) would have contracted for the capability of sending a ton of data via expensive satcom links in real time, when they could download it (presumably for free) at the end of every flight, or at some more convenient interval, then Asian LCCs wouldn't be top of my list.
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Old 2nd Nov 2018, 23:29
  #472 (permalink)  
 
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"FEEL DIFF PRESS LT ILL"

If confirmed, the preceding flight reported "IAS & ALT DISAGREE SHOWN AFTER TAKE OFF" and "FEEL DIFF PRESS LT ILL". Assuming that despite overnight maintenance actions both issues re-occured on the accident flight, these combination may be quite significant, not only in terms of their cause, but for the sad outcome of this flight mainly in terms of their effect, in particular of the second message.

As concerns the cause, it would seem to me relatively rare for several pitot systems to fail simultaneously. To note that the ias/alt pitot system is separate from the elevator pitot system, the first being located at the front of the A/C, the second on each side of the front base of the V/S. (Repeated) Simultaneous failure of both systems would IMO indicate something more structural then the pitots themselves.

As to the effect, in particular the "FEEL DIFF PRESS LT ILL" could be of particular relevance. The elevator feel computer provides simulated aerodynamic forces using airspeed (from the said elevator pitot system) and stabilizer position. Feel is transmitted to the control columns by the elevator feel and centering unit. To operate the feel system the elevator feel computer uses either hydraulic system A or B pressure, whichever is higher. When either hydraulic system or elevator feel pitot system fails, excessive differential hydraulic pressure is sensed in the elevator feel computer and the FEEL DIFF PRESS light illuminates.

I stand to be corrected, but if (barring hydraulic problems) the elevator feel and centering unit enters into a condition that triggers the FEEL DIFF PRESS annunciation (for whatever reason, either pitots or a more systemic failure, since in this case also the "main" pitot system could have been affected simultaneously), it would mean that particularly in manual flight the elevator inputs through the control columns could have a much different (greater) effect than normal. It would be interesting to know whether such inputs with a "dysfunctional" feel and centering unit could lead to upsets with an ultimate loss of control, which at relatively low altitude would be difficult to recover from in time.

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Old 3rd Nov 2018, 00:39
  #473 (permalink)  
 
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The Maintenance Release shows the time 12:40 UTC. The aircraft landed at 15:55 UTC (22:55 local time). Maybe the airworthy release was signed at 00:40 local time on 29th, but still only 1h45min to fix two malfunctions.
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Old 3rd Nov 2018, 01:35
  #474 (permalink)  
 
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Lots been said about pilots who can't hand fly. So a Virgin Australia 777 driver would get more hand flying or a 737 driver doing island hopping with different terrain, airports and 3-4 sectors a day? Poor pilots are not those who cannot fly manual but those who do not have sufficient understanding of the increasingly complex aircraft systems. In particular, the flow on effects and consequences when a part of that system fails.
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Old 3rd Nov 2018, 01:36
  #475 (permalink)  
 
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Angry

Originally Posted by birdspeed View Post
So, are we looking at a UAS event causing false inputs into the STS? This puts in a nose down trim, the pilots counteract with nose up elevator. Without any throttle reduction the aircraft accelerates to high speed until something snaps. As no other separate floating debris field has been found, and a near vertical dive, I suspect it was the stab trim screw jack that gave way at the end.
Please do not assume- speculate on so called structural failure of the empanage area without any clue as to a control issue or not

given the so called speeds probable a impact - it is unlikely a major structural failure was involved- but until data is released, such speculation is just that - and besides it was not a dc9 . . with a totally different isssue re screw jack
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Old 3rd Nov 2018, 01:37
  #476 (permalink)  
 
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Originally Posted by FL11967 View Post
Poor pilots are not those who cannot fly manual but those who do not have sufficient understanding of the increasingly complex aircraft systems. In particular, the flow on effects and consequences when a part of that system fails.
False dichotomy. Either or both of those things are the mark of a poor pilot.
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Old 3rd Nov 2018, 04:21
  #477 (permalink)  
 
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but those who do not have sufficient understanding of the increasingly complex aircraft systems. In particular, the flow on effects and consequences when a part of that system fails.
They may well have plenty of understanding but in today's environment the crew simply follow what the QRH or recall says to do. They have to, there is no choice. When multiple failures occur the crucial aspect is determining the root cause. I have been with crew in the sim that announced a generator failure, the actual failure was an engine failure, inability to sort the wheat from the chaff will kill people. Knowing WHICH QRH item or recall to do first is important,
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Old 3rd Nov 2018, 04:54
  #478 (permalink)  
 
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Originally Posted by FL11967 View Post
Lots been said about pilots who can't hand fly. So a Virgin Australia 777 driver would get more hand flying or a 737 driver doing island hopping with different terrain, airports and 3-4 sectors a day? Poor pilots are not those who cannot fly manual but those who do not have sufficient understanding of the increasingly complex aircraft systems. In particular, the flow on effects and consequences when a part of that system fails.
It’s more a culture problem that originates way back to even CPL training. Which is why a lot of Asian carriers send them to Australia. Indonesia does not.

A Virgin 777 pilot has most likely been on the 737 for a number of years before moving up.

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Old 3rd Nov 2018, 06:15
  #479 (permalink)  
 
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Originally Posted by FL11967
Poor pilots are not those who cannot fly manual but those who do not have sufficient understanding of the increasingly complex aircraft systems. In particular, the flow on effects and consequences when a part of that system fails.
I'm with Iccy; this is rubbish. Virtually every loss of control accident recently has been because the crew couldn't fly. You can memorise reams and reams of books and be able to describe how to build and aeroplane in intricate detail, but if you cannot fly, if you cannot push aside all of that stuff and just keep the thing wings level and with a reasonable power setting, it's all for nought. In fact, there is a good argument that saying we need more and more systems knowledge is covering/hiding the absolute need to be able to basically fly.

Keep/get the aeroplane wings level, in level(ish) flight, with a reasonable power setting/GPS speed, then do your diagnosing. And as Iccy says, if we can identify what the issue/warning is, we have to do what the QRH says. This isn't some gathering of engineers in a room pondering what to do next. Do what the QRH says. If some weird crazy thing happens that isn't covered, then by all means use your systems knowledge to get yourself out of it, but to my knowledge there hasn't been a recent prang caused by lack of knowledge of an aircraft system.

Of course, it's much easier to test systems knowledge at a computer screen than it is to give pilots initial/continued training in stick and rudder skills...
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Old 3rd Nov 2018, 06:33
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Have not seen any mention of CCTV from JKT ground ops/control of a 737 with streamers on the side of it taxiing/departing?
Pitot covers would surely have have red 'Remove before flight' streamers - new A/C standard equipment?
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