Indonesian aircraft missing off Jakarta

[climber314]

Provided that, at 0.27 degrees per second, it is allowed to run uninterrupted for a tad over 9 seconds.

The design seems to fail "on" by which I mean to say a bad sensor is able to trigger the software to continue to say "Nosedown" to MCAS. This seems to be opposite to conventional wisdom where a device is designed to fail "safe" or in other words say to MCAS "do nothing". That's my understanding at this point.

Pretty simple to program if AoA = disagree then MCAS = off. That may be simplistic but may well be something like what Boeing is considering? Whether this or something else they come up with meets certification requirements is yet to be seen.

Exclusive: Boeing eyes Lion Air crash software upgrade in 6-8 weeks
https://www.reuters.com/article/us-indonesia-crash-boeing-exclusive/exclusive-boeing-eyes-lion-air-crash-software-upgrade-in-6-8-weeks-idUSKCN1NZ00S

[LDRA]

It's two subtly but significantly different statements.

that attributed to Boeing - "pilots weren’t ever likely to encounter" sounds like the kind of wording used in failures assessment guidance. (I suspect if I dug deep enough i could find it verbatim in guidance somewhere) On the other hand, "it'll never happen" is not the kind of statement any certification engineer would ever be capable of or comfortable making, and I'm guessing it's a paraphrasing (with a dollop of simplification) of the former statement.

Fair enough. But if they actually did failure analysis and quantified failure rates properly, like they are supposed to, it would have been glaring obvious the "unintended activation" has a high occurrence rate, and a single point failure at that.

[jimtx]

Disturbing statement, shows lack of safety culture and lack of understanding of how safety works.

If the safety system will never be used, why develop and install in production aircraft in first place?

What would be interesting to know is how a Brazilian Max operator, GOL, implemented the type B training and checking for the MCAS system and what their pilots were told about the system.

[Mad (Flt) Scientist]

Fair enough. But if they actually did failure analysis and quantified failure rates properly, like they are supposed to, it would have been glaring obvious the "unintended activation" has a high occurrence rate, and a single point failure at that.

Even assuming you did that - and I am sure they did do the corresponding analysis, we can argue about "properly" - you'd still be left with determining the hazard classification.

I rather believe that faced with a similar failure scenario - low speed limited authority "uncommanded motion" of the stab (it's commanded, but not in the circumstances truly intended) - with the pre-existing ability to disable the system and a pre-existing procedure which would address the runaway case (if somehow it repeated) then that would probably be classified as no more than a MAJOR hazard. In other words, I strongly suspect (and this may be an unpopular view) that the system as has been presented in public information is perfectly certifiable, and I suspect analogies could be found on other aircraft.

[LDRA]

Even assuming you did that - and I am sure they did do the corresponding analysis, we can argue about "properly" - you'd still be left with determining the hazard classification.

I rather believe that faced with a similar failure scenario - low speed limited authority "uncommanded motion" of the stab (it's commanded, but not in the circumstances truly intended) - with the pre-existing ability to disable the system and a pre-existing procedure which would address the runaway case (if somehow it repeated) then that would probably be classified as no more than a MAJOR hazard. In other words, I strongly suspect (and this may be an unpopular view) that the system as has been presented in public information is perfectly certifiable, and I suspect analogies could be found on other aircraft.

Agreed, except "pre-existing procedure" implies there are defined criteria for DETECTING failure condition, which does not exist before the FAA AD came out. Even with the FAA AD, the flight crew identifiable symptom is a large laundry list, which is not ideal.

Similiar system on 737, STS has its own warning lamp to properly indicate failure to flight crew, per FAR25.672a clause

[CurtainTwitcher]

I have a copy of the QRH Runaway Stabilizer NNC (my bold):
Condition: Uncommanded stabilizer trim movement occurs continuously

From the FDR traces, the failure mode does not appear at face value to meet the NNC condition statement. The adverse trim will stop for 5 seconds after pilot manual electric trim. This is an intermittent uncommanded trim mode, not continuous (as per NNC condition statement). Was this taken into account with the failure mode analysis?

In the failure mode analysis, would this condition statement be true for the single point failure (AoA signal) to be classified only as a major hazard, given that it could also generate an intermittent trim movement under some conditions (flaps up), continuous stick shaker AND UAS simultaneously.

In other words, with the design of this MCAS system, a single point failure has created a very complex scenario. Did Boeing actually consider the combined interactions of each of these outcomes in totality or individually when classifying the hazard? I would view the resultant accident as an indication of failure of the failure mode analysis. Why was the analysis flawed, that is the big question.

While you are contemplating this, try putting up with what this crew had to endure while they were trying to figure out what was going on.


TrjTUvhpBlE

[alf5071h]

CT, Good points about certification process. How might EASA have evaluated this; rubber stamp, or take an active interest in the specific changes ?

See the discussion re drills and training here :-
https://www.pprune.org/rumours-news/614857-indonesian-aircraft-missing-off-jakarta-98.html#post10327203

[b1lanc]

What would be interesting to know is how a Brazilian Max operator, GOL, implemented the type B training and checking for the MCAS system and what their pilots were told about the system.

And I'm still wondering why only Brazil? That information had to come from Boeing. Why not world-wide disto?

[MickG0105]

Hi Mick. I would suggest the difference in view is due to a difference in how you interpret the second last sentance, in the description of MCAS's operation. ...

Thanks for that summary. FCeng84 seems to have the inside dope on MCAS so I'll happily defer to his explanations. I would make a couple of points though:

1. Neither the FAA nor Boeing were particularly forthcoming in their initial correspondence to operators on this matter. Neither the FAA Emergency AD or the Boeing FCOM Bulletin mentioned MCAS. Boeing's bulletin simply stated that
'In the event of erroneous AOA data, the pitch trim system can trim the stabiliser nose down in increments lasting up to 10 seconds.'
That statement neatly sidesteps the fact that on the B737, AOA data had never previously been used to directly inform 'the pitch trim system'.

2. Having had at least another three days to come up with a clear description of MCAS the best that Boeing could manage was still somewhat ambiguous. What the subsequent Boeing correspondence fails to make clear is that:

a. In the absence of crew trim inputs, MCAS will only make one nose down trim adjustment of up to 2.5 units.

b. MCAS is apparently not interested in overcoming the attitude condition that triggered it - having made its initial nose down trim adjustment the trigger condition AOA can persist and (so long as there is no crew trim input) MCAS will do nothing further.

c. MCAS also apparently makes a subsequent nose up trim adjustment to return the stabiliser to the previously trimmed position.

3. Boeing fails to make it clear that a trigger for MCAS to continue trimming in more nose down trim is a countermand from the crew. Frankly, I think that is astounding. The system will ignore the persistence of the trigger condition after it makes its initial nose down trim adjustment but it will make a further nose down trim adjustment if the crew countermands it! Moreover, it will do that each and every time the crew countermands it. That is a very clear cut case of an automated system that is designed to override a specific crew command. To borrow an image from Gums, when the crew looks to wind off some of the automatically commanded nose down trim, HAL says, 'I'm afraid I can't allow that, Dave.'

[megan]

A top executive at a 737 MAX customer agreed pilots didn’t need to know the system’s details. “They’re not engineers and their job is to fly the aircraft,” this executive said."And he probably has a new crop of pilots in training. :*

https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/720x960/do_9aa433a0ac04504e4f341ced58e9dd918e24503f.jpg

[rubik101]

What was wrong with the old system? :cool:

[Loose rivets]

Mr Cheese.

I see lots of folks assuming MCAS trims 2.5ND each time - but that's not what I get from the description of MCAS, which provides: Stabilizer incremental commands are limited to 2.5 degrees and are provided at a rate of 0.27 degrees per second. The magnitude of the stabilizer input is lower at high Mach number and greater at low Mach numbers.

So - depending on speed and AoA, MCAS will trim up to 2.5ND - correct? Or - is there something else that confirms MCAS trimmed JT610 2.5ND repeatedly, and then continuously?

It's just that one letter that makes the difference. It suggests ". . . limited to 2.5 degrees each and are . . ." might be an improved wording.

[jimtx]

What was wrong with the old system? :cool:

The old system required you to roll into a 45 degree bank in the simulator and raise the nose the degree or two to maintain level flight, increasing the load factor, and either holding pressure or trimming it off while getting your instrument crosscheck warmed up. The new aerodynamics of the Max, if replicated in whatever simulator might have them, might allow you to roll into 45 degree bank and as you pulled , you might not have to pull anymore or pull less because the engines aero effect started pulling for you. What's wrong with that I don't know. If you have a good crosscheck you fly the attitude and performance instruments and do what ever it requires with the stick. If there is any other flight envelope where the old system would be deficient for the MAX and you needed the MCAS we don't know and Boeing isn't telling us but previous threads have hinted that a normal flight would never see it. This is all supposition by me wondering why steep (or step) turns were mentioned in the one of the Boeing blurbs.

[Volume]

Why did Boeing not fit a stick nudger as was done for the 747 on the British register?
Because the elevator alone seems to be not powerful enough, no matter whether the pilot or an actuator pushes it. Obviously nose down trim is required to create enough nose down pitching moment. Which does not speak for the design, but is typical for the late 50s, when most elevators were so small that no hydraulic power was required to operate it.
If the 737 MAX would be a clean sheet design, the horizontal stabilizer and elevator would for sure look differently.

Trim has always been a killer item requiring close attention and it will always be, even if now a box of chips and a bunch of sensors pays the attention. Having new aircraft designs without a trim wheel is unbelieveable for me, but it becomes the standard. Trim becomes a computer assist item.

[aeromech3]

During each pre-flight, admittedly in a different airframe, each pilot would test the stick shaker and I would expect from that, they would be quite used to the feel on their column and sound, is it the same on the B737 MAX ?

[WillFlyForCheese]

Mr Cheese.
It's just that one letter that makes the difference. It suggests ". . . limited to 2.5 degrees each and are . . ." might be an improved wording.

yes, but limited to 2.5 AND each time - depending on speed and AoA. It appears as though everyone is assuming it trimmed at the max limit each time - and I’m curious where that information is found. How do we know, for example, MCAS didn’t trim 1.3 AND each time, if that’s what speed and AoA called for? Or 0.7 . . .or 2.1?

[FCeng84]

To borrow an image from Gums, when the crew looks to wind off some of the automatically commanded nose down trim, HAL says, 'I'm afraid I can't allow that, Dave.'


MickG - careful now. This is not at all a matter of HAL saying "I'm afraid I can't allow that, Dave." What is happening here is that MCAS has inserted a nose down stabilizer motion increment in response to its understanding that the airplane is at high AOA. The pilot has then manually re-positioned the stabilizer. MCAS is in no way preventing the pilot from moving the stabilizer in either direction as much as the pilot wants. MCAS is further waiting five seconds to allow the pilot to make sure that the pitch trim situation is to the liking of the pilot. If the pilot is not satisfied with the pitch trim and makes another manual trim input, MCAS sits it out for another five seconds. Only after that does MCAS make a new assessment as to whether or not the conditions exist (flaps up, proper speed range, and high indicated AOA) to trigger MCAS to insert a limited increment of nose down stabilizer motion. The design assumption here is that when a pilot makes pitch trim inputs, those inputs will be in the direction to trim the airplane such that each time MCAS makes its assessment as to whether or not to add more nose down, it is starting from a relatively trimmed condition. The pilot maintains highest priority for stabilizer control throughout and MCAS only moves the stabilizer a limited increment each time that the pilot finishes trimming manually.

While it does not present itself as continuously running run-away automatic stabilizer motion, with the airplane flying at a relatively steady flight condition repeated instances of the system moving the airplane away from the trim condition that the pilot has established manually should be recognized as improper automatic stabilizer operation and disabled via the cutout switches.

[FCeng84]

Volume - MCAS was not introduced to make up for deficient elevator nose down control authority. MCAS is there to improve handling characteristics as proscribed by the FARs at elevated AOA. The pilot has plenty of control power to lower the nose via the column. That is not the issue.

[Bergerie1]

Any of you who are interested in flight test and the required handling qualitiies of aircraft, particularly at the stall, will probably enjoy these podcasts and find them most informative. At 1hr 14mins into the second podcast he describes the 707 and in the third he talks about the 747 and later the T-tail aircraft. Much of what he has to say is relevant to this 737 accident.

https://www.pprune.org/tech-log/602953-d-p-davies-interviews-certificating-aircraft.html#post9985073

[Jetthrust]

Boeing fails to make it clear that a trigger for MCAS to continue trimming in more nose down trim is a countermand from the crew. Frankly, I think that is astounding. The system will ignore the persistence of the trigger condition after it makes its initial nose down trim adjustment but it will make a further nose down trim adjustment if the crew countermands it! Moreover, it will do that each and every time the crew countermands it. That is a very clear cut case of an automated system that is designed to override a specific crew command. To borrow an image from Gums, when the crew looks to wind off some of the automatically commanded nose down trim, HAL says, 'I'm afraid I can't allow that, Dave.

That was my view also. But, after reading FCeng84’s comments to this statement, I would explain it this way. Let’s assume the system logic was the opposite. That is, if after MACS commands a pitch change, the pilot uses the electric trim switch or manual trim wheel, MACS says “ok, the pilot has deliberately changed the pitch, I will disable myself”. For how long should MACS remain disabled? What happens if 20 min later, the AoA gets into dangerous territory? Clearly, a time period needs to exist at which MCAS becomes re-enabled. So, this reverse logic scenario is actually exactly how it does work. It’s just that the time period, according to FCeng84 who seems to know this system well, is 5 seconds. (Which given how quickly an aircraft could get out of control, is probably quite a long time?)

[Loose rivets]

Mr Cheese

yes, but limited to 2.5 AND each time - depending on speed and AoA. It appears as though everyone is assuming it trimmed at the max limit each time - and I’m curious where that information is found. How do we know, for example, MCAS didn’t trim 1.3 AND each time, if that’s what speed and AoA called for? Or 0.7 . . .or 2.1?

First, there is that AND word, which an earlier poster suggested, ' . . . AND, and etc., etc.'

Again, wording is so critical. But your main point: while the extent of the trim via the mini-corrections IS variable, (i.e. Mach), for the most part the repeated blips are very similar on the graphs available to us. Although the Mach modification is very small, it does get me wondering what it was doing during the fatal dive.

[A0283]

Rounded estimate of the status of the identification process based on public information - and excluding empty seats:
About 50% of those in front rows have been identified.
About 25% of those in the back rows have been identified.
The cabin apparently had seatrows numbered 1-34 but probably excluded rows 13 and 14 (in spite of 1 passenger mentioned to be in 13).
Standout is seat column F which has the largest percentage missing.

From the data it is not possible to estimate where the 3+3 cabin crew were seated. A guess is that at least 1 in a front folding seat, and 2 at the back galley, with the 3 trainees in row 1 seats DEF.

It suggests a nose down impact and right hand roll (more than 90 degrees would not surprise me).

[Machinbird]

MCAS was not introduced to make up for deficient elevator nose down control authority. MCAS is there to improve handling characteristics as proscribed by the FARs at elevated AOA. The pilot has plenty of control power to lower the nose via the column. That is not the issue.
FCeng84, could this statement be also interpreted as fixing a non-linearity in control response at high AOA? Is that the type of improvement in handling characteristics being created?

[Ian W]

Mr Cheese


First, there is that AND word, which an earlier poster suggested, ' . . . AND, and etc., etc.'

Again, wording is so critical. But your main point: while the extent of the trim via the mini-corrections IS variable, (i.e. Mach), for the most part the repeated blips are very similar on the graphs available to us. Although the Mach modification is very small, it does get me wondering what it was doing during the fatal dive.

The ratchet effect exists - and is very apparent from the post of the FDR permalink here to post (https://www.pprune.org/rumours-news/614857-indonesian-aircraft-missing-off-jakarta-89.html#post10323037)

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/1955x450/952eaf24_520f_4384_bd7e_949cfcb91ebb_79fda400669b1e28f237699 94137618b2161cdb0_jpeg_bfa9fff3b138685428996bb35e72996b67acd a9b.jpg



Regardless of wordings in spec, the pitch trim position can be seen to 'ratchet' down in 3 full steps without correction back by the PF who just blips the trim. From the scale on the left of the image the stab trim reached max nose down.

[Mad (Flt) Scientist]

Something I'd not noticed before on that FDR data - not sure it's been remarked on. At the VERY end of the trace, the stab is seen to apparently move a long way back towards to trim state. Given the compressed scale, it's not possible to see if that is a "final instant" artifact and not "real" or if there's an actual slope to the stab trace. If it's "real" it indicates that the stab remained under the potential for crew control throughout the flight to the very end, and that the ratcheting prior to that was not "uncorrectable".

[climber314]

The graph in the report shows a number of the parameters end in vertical lines like that.

[FCeng84]

.
FCeng84, could this statement be also interpreted as fixing a non-linearity in control response at high AOA? Is that the type of improvement in handling characteristics being created?

To address your question I think it is important to be very clear with regard to your phrase "non-linearity in control response". The FAR in question speaks to the progression of column pull force required to command increased AOA. Well behaved stability characteristics would involve the need for the pilot to apply ever increasing column pull to command ever increasing AOA. Not having that desired characteristic could be a result of either the pitching moment vs. AOA (Cm-alpha) characteristic of the overall airplane or the pitching moment vs. column (Cm-column or similarly Cm-elevator) generated via deflection of the column. The net effect that the FARs speak to is how these two sources of pitching moment (AOA vs column) balance one against the other.

The issue that MCAS addresses is non-linearity of Cm-alpha stability derivative. The pitching moment generated by the elevator (and thus the column) is much more linear. As I have mentioned in previous posts, it is not a matter of the pilot having insufficient ability to generate pitching moment via the column. The issue is that as AOA increases into a range higher than normal operation (near and beyond the AOA for stick shaker activation), the amount of nose down pitching moment generated by additional increase in AOA is not sufficient to require the FAR mandated increase in column pull to balance.

[climber314]

While you are contemplating this, try putting up with what this crew had to endure while they were trying to figure out what was going on.

CT with all due respect... I don't see anyone disputing that Boeing's MCAS system ran the nose down and crashed the jet killing 189 people, but it is noteworthy that two switches may have prevented this tragedy.

What remains to be seen is how ambiguity in the QRH, distraction, lack of training, a flying spanner, CRM, or perhaps even crew competency factor in as possible contributing causes.

"We study and discuss accidents so we don't become the subject of a thread on PPRuNe."

[DaveReidUK]

but it is noteworthy that two switches may have prevented this tragedy

Or, come to that (with 20/20 hindsight), simply grabbing and holding the trim wheel.

N.B. No criticism of the crew intended.

[Lonewolf_50]

I am with gums on this one, in terms of "if something moves the flight control surfaces, the pilots need to be aware that it exists and how it helps them, and thus some training/education is required." Also needed for safe operations is "what turns it on or off" if it moves the flight control surfaces.
That quoted "executive" needs a talking to from the pilot's union.
Anything that is built can break, anything with computer code or electricity involved can malfunction.

Question on the MEL: is one AoA sensor INOP a downing discrepancy? I'd assume so, but I've been surprised before.

[ampclamp]

CT with all due respect... I don't see anyone disputing that Boeing's MCAS system ran the nose down and crashed the jet killing 189 people, but it is noteworthy that two switches may have prevented this tragedy.

What remains to be seen is how ambiguity in the QRH, distraction, lack of training, a flying spanner, CRM, or perhaps even crew competency factor in as possible contributing causes.

"We study and discuss accidents so we don't become the subject of a thread on PPRuNe."

Regardless of the fault or cause, one does wonder after all those trim corrections, or whatever fault that caused the trim to run counter to where they wanted it , at what stage would the crew have used those switches.

[Mad (Flt) Scientist]

Question on the MEL: is one AoA sensor INOP a downing discrepancy? I'd assume so, but I've been surprised before.

B-737-8/9 MMEL on FAA website (rev 1, Jan 2018) only mentions AOA heater as related MMEL option; AOA sensor itself does not appear on MMEL. (Based on a few search terms)

[CONSO]

from this SLF- when ONE faulty sensor input allows " hal " to override manual control AFTER correction by the pilots without warning or deliberate reset, without notice, or mention, the " chain of command" which allowed/approved/designed such a process to be incorporated needs to be held responsible.

[Loose rivets]

Well yes, but the majority of the thread is leaning towards the stabilizer not being disabled. Something is nagging away in the back of my mind. Stabilizer runaway memory actions are so fundamental that the thread's detective logic changed quickly to looking at the ~5 second delay adding to the confusion of an already chaotic flight-deck - causing a radical diversion from old established SOPs.

The relatively calm ATC and the prolonged period of approximate hight holding, coupled with the huge handful of power in the last moments, is leaving me with a mind that's wide open.

[Roger_Murdock]

Stabilizer runaway memory actions are so fundamental that the thread's detective logic changed quickly to looking at the ~5 second delay adding to the confusion of an already chaotic flight-deck - causing a radical diversion from old established SOPs.

There seems to be a significant amount of hindsight bias regarding the specific term "runaway". A lot of the discussion is now anchored to what has been revealed about MCAS and the behavior of this aircraft. If you survey every single poster in this thread before this incident and asked them to describe what "runaway stabilizer" looks like, I imagine the answers would be quite different than what you would get in a poll with hindsight of this incident. For an example of a 2016 reference guide description of runaway stabilizer, google: The Ultimate B737 NG Technical Handbook STABILISER TRIM SYSTEM AND RUNAWAY STABILISER

It's not even clear that the previous crew diagnosed a "runaway" and followed the NNC. They may have gone directly to the cutout switches as a way to isolate an unknown electrical trim problem- they later reported that they believed it was STS operating in reverse due to IAS issues. This may even have been a conclusion/guess they reached later in the flight rather than a contemporaneous diagnosis.

EDIT: climber314 pointed out that the preliminary report says they followed the Runaway Stabilizer NNC. Hopefully we get more specifics on this later.

[arba]

https://cimg7.ibsrv.net/gimg/pprune.org-vbulletin/1668x1416/7f2cf11d_f89d_44dd_aa29_66f6dd5613f5_dd654eb82e206b586b30656 6c5b0cafebedf53ff.jpeg
Why didn’t they get this ?

[climber314]

It's not even clear that the previous crew diagnosed a "runaway" and followed the NNC.


The JT43 crew ran the R/S NNC and cut out Stab Trim. I posted this shortly after the report was released.
https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/769x189/screen_shot_2018_12_06_at_8_34_16_pm_837a9ba895afc0c9b36b28c 4625d5720e61039fb.png

[pilot9250]

While it does not present itself as continuously running run-away automatic stabilizer motion, with the airplane flying at a relatively steady flight condition repeated instances of the system moving the airplane away from the trim condition that the pilot has established manually should be recognized as improper automatic stabilizer operation and disabled via the cutout switches.

I think it's a fair distinction to raise but feel this presentation is disengenous.

As far as we can tell, MCAS is intended to provide a more consistent and predictable handling response in incipient stall conditions.

How does an intermittent and unadvertised control input, of complex algorithmic intensity, every 5 seconds, provide that?

[Roger_Murdock]

The JT43 crew ran the R/S NNC and cut out Stab Trim. I posted this shortly after the report was released.

Sure enough. Is that statement based on interview with the crew?

[climber314]

Sure enough. Is that statement based on interview with the crew?

My assumption is they were debriefed. The whole flight is described in detail in a little over one page - 18.1 PK-LQP Previous Flight.

[CONSO]

https://cimg7.ibsrv.net/gimg/pprune.org-vbulletin/1668x1416/7f2cf11d_f89d_44dd_aa29_66f6dd5613f5_dd654eb82e206b586b30656 6c5b0cafebedf53ff.jpeg
Why didn’t they get this ?


Suspect it was a delete option- not a standard display... If my memory of earlier discussion in this thread is correct ...

[Machinbird]

When I first saw the column force charts on FDR data, one thing that impressed me was the force applied was very ragged toward the end of the flight.
https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/283x222/jt610_control_force_64345f53fd8885148ae04ae058be460a847c663d .jpg

Control Column Force Applied

Then there was this comment by birdspeed which prompted an examination of the breakout mechanism which separates the two control columns if one side becomes jammed.
What perhaps happens is a breakout of the control yokes just before the dive. FDR shows a difference in the applied control force on the yokes. I believe when elevator breakout occurs there is sudden loss of elevator effectiveness. This would cause a sudden bunt over, with a wtf moment and the pilots stopped any sustained opposite trim.
There was then an interesting NTSB Safety Recommendation A-11-7 through -11 dated February 2010 which discussed several control jam incidents and indicated that the 737NG (and MAX I assume) had some additional features not found on the earlier 737-300 through 737-500 aircraft. and were improved by the addition of several mechanical override mechanisms. One form of these mechanical override mechanisms is called a POGO. See this link for an explanation Pogo Load Limiter; (http://daerospace.com/mechanical-systems/load-limiter-pogo/) Pogos are spring loaded linkages that act as a rigid link until a sufficiently high level of force is reached. Then the spring begins to allow motion and effectively disconnects mechanisms downstream of the POGO (which would normally have to be jammed for sufficient force to be generated.)

When you pull back on the control column inflight, you are not actually pulling back against the air loads on the elevator. That surface is being moved by an irreversible hydraulic cylinder. What you actually are working against is the elevator feel and centering unit. that applies force (torque) on the Elevator PCU input torque tube and which is actuating two elevator Power Control Unit hydraulic cylinders. One for the right elevator and the other for the left elevator. Both elevators are synchronized by the elevator torque tube. There is a pogo unit going to each elevator PCU control valve. Normally, the input valve force needed is rather light but should the PCU control valve jam, then its POGO will allow the rest of the input mechanism to move so that you can still actuate the opposite PCU control valve.

One thing I have not yet been able to establish is whether there are additional POGO-like devices installed between the individual control columns and the PCU input torque tube. If each column was connected directly to the PCU input torque tube, then activation of the breakout mechanism would seem to have minimal ability to free up a jam on one side of the control system forward of the elevator PCU input torquel tube since the control cables would back drive the opposite control column. I speculate that there are indeed POGO-like override mechanisms between the control columns and that they are set to a rather high force differential that would not be normally encountered. (More on this in a minute)

The elevator feel and centering unit applies its force profile on the PCU iinput torque tube by means of a linkage. As we can see from the force applied by the JT610 crew, they applied in excess of 100 lb force to the column during the final seconds. Suppose this level of force was sufficient to override the POGO unit on that side of the control pathway. leading to the elevator PCU input torque tube. If that happened, pulling further back on the control column would do nothing more! Remember, the trim had just reached full nose down. Could that be what the JT610 crew was trying to figure out by moving the controls, trying to find a spot that would "grab" and increase g? It would have felt like a control disconnect. Not the kind of thing that they would have had time to figure out once the nose began to drop.
For links to two more detailed posts on this subject in Tech Log see:Cockpit End Discussion (https://www.pprune.org/10326605-post33.html) and Elevator System Discussion (https://www.pprune.org/10328753-post34.html)

[Lonewolf_50]

Suastiastu: noting the comparatively stable vertical speed (in terms of error band) that you point to, is it your idea that something new happened (maybe something broke) in the last half of a minute? When I look at the match up of the reported radio conversation between the aircraft and ATC as they were arranging their return, the impression I was left with was that the aircraft was more or less controllable, and then all of a sudden it wasn't.

This discussion takes me to a related incident that did not include a failure in the air (ILS Glide Slope gone bad) that has to do with corporate culture and even industry culture.

The previous crew who hand flew this bird back (whether or not they diagnosed the problem right) may have had a slightly different mind set, informed by company and industry culture, than the subsequent crew. In discussing the choice to hand fly the approach once the GS and the assisted approach has gone south, or to go around and try another approach, the following question is asked (in hindsight) for the recent approach that went around after their approach went unstable due G/S signal being bad.Jet Jockey A4 (http://www.pprune.org/rumours-news/616082-air-india-b788-descends-200-ft-over-water-hkg.html#post10329226) : If you know there is a possible problem with the G/S signal and no other type of approach is available, why not hand fly the aircraft?Capn Bloggs (http://www.pprune.org/rumours-news/616082-air-india-b788-descends-200-ft-over-water-hkg.html#post10329258) : You just never know when the technology is going to try to kill you! Jet Jockey, you'll be put in the sinbin for suggesting that.




Granted, that interchange is light hearted, but I think it gets at an issue regarding mind set in any given crew who are confronted with "eh, it's not working right ..." Those mind sets, or operating assumptions, are informed by organizational culture.
I am sure that discussions will continue regarding "why not turn it off and hand fly?" in this case, after the fact, but I note that crew in the bad ILS being discussed in the other thread didn't do that. (For my money, that close to the ground if things get unstable Go Around is something we were all taught in the beginning: no approach is too perfect that it can't be waved off ...)

How comfortable were these two pilots Lion Air with hand flying?
How comfortable were they with shutting systems off and flying the bird by hand? (The previous crew may have had a different comfort zone than the crew on this fateful day).
How much sim time, or flight time, did they have doing that hand flying thing?

Or, did something else break as the crew were dealing with "all this" and the investigators have not yet hit upon that failure as they go through their difficult and demanding tasks? I am reminded of the difference in the understanding of the AF 447 crash before and after the boxes, and their information, came to light.

We humans tend to do what we are comfortable with, though training can help us broaden our comfort zone. When the CVR is found, a lot of what I am wondering about in this accident will get answered, I think.

[infrequentflyer789]

That statement neatly sidesteps the fact that on the B737, AOA data had never previously been used to directly inform 'the pitch trim system'.


Mmm, might want to check with respect to the NG. Maintenance manual (don't have FCOM but be interested to know what is in it on this) says:

Near stall, the speed trim function trims the stabilizer to a nose down condition to allow for trim above the stickshaker AOA and idle thrust. The trim continues until the stabilizer gets to its limits or the aft column cutout position is exceeded

Note: FCC / speed trim functional diagram labels this function "stall detection circuit".

MCAS is different in several ways (not least that various folk are saying earlier in the thread that MCAS is not about stall or stall detection). I doubt that this NG "stall detection" (and action) is still part of speed trim function in the MAX, I suspect that MCAS has replaced it (and probably evolved from it). One or more of the MCAS differences must account for the fact that Boeing and the FAA both appear to believe that JT610 cannot happen on an NG, and that may also be the key to understanding it, but I'm not convinced we even understand all the differences yet.

[FCeng84]

I think it's a fair distinction to raise but feel this presentation is disengenous.

As far as we can tell, MCAS is intended to provide a more consistent and predictable handling response in incipient stall conditions.

How does an intermittent and unadvertised control input, of complex algorithmic intensity, every 5 seconds, provide that?'

Turbine70 - the "intermittent and unadvertised control input" that the JT610 crew experienced was a result of the AOA sensor failure combined with MCAS. I agree with your questioning how that could provide "consistent and predictable handling response in incipient stall conditions." It would not. With a properly functioning AOA sensor, MCAS will only take action when AOA is high, approaching stall and thus provide a tendency for the airplane to lower its nose and thus aiding with recovery from the high AOA condition.

[Loose rivets]

Lonewolf 50:

noting the comparatively stable vertical speed (in terms of error band) that you point to, is it your idea that something new happened (maybe something broke) in the last half of a minute? When I look at the match up of the reported radio conversation between the aircraft and ATC as they were arranging their return, the impression I was left with was that the aircraft was more or less controllable, and then all of a sudden it wasn't.

That is precisely what I've been getting at - not least of all because of the last minuet huge increase in fuel flow.

My comment earlier about a standard reaction to stabilizer runaway, intentionally disregarded the different symptoms the pilots would have been subjected to on the MAX. I'm trying to get into the pilot's minds and the comment was based on up to date training having been denied them and their mindset locked to an age-old operating procedure. Surely, even then, they would have gone for the cut-out switches, and if they did not, it was because something entirely different was also confusing the issue. By that I mean in addition to the five-second delays etc.

Indeed. Just imagine not knowing.

How does an intermittent and unadvertised control input, of complex algorithmic intensity, every 5 seconds, provide that?

[A Squared]

'

Turbine70 - the "intermittent and unadvertised control input" that the JT610 crew experienced was a result of the AOA sensor failure combined with MCAS.

That is true, but from the descriptions I have read of the MCAS, my understanding is that this is exactly the way the MCAS would behave in an actual high AoA situation, intermittent adjustments of stabilizer position. In other words, the "intermittent" part wasn't a result of the bad AoA data, the erroneous AoA data was consistently and continuously high, and the MCAS was responding as it was designed to respond to a high AOA.

[FCeng84]

That is true, but from the descriptions I have read of the MCAS, my understanding is that this is exactly the way the MCAS would behave in an actual high AoA situation, intermittent adjustments of stabilizer position. In other words, the "intermittent" part wasn't a result of the bad AoA data, the erroneous AoA data was consistently and continuously high, and the MCAS was responding as it was designed to respond to a high AOA.

With correct AOA supplied to the MCAS function, it will begin automatic nose down stabilizer insertion when AOA first exceeds the MCAS activation AOA threshold. The amount of stabilizer motion that MCAS will command is a function of speed and the degree to which AOA exceeds the MCAS activation threshold. The flight deck effect is that the pilot will find that as AOA increases, the airplane has and ever increasing tendency to lower the nose to recover. Keep in mind that the stick shaker will also activate giving the pilot both auditory and tactile cues that AOA is above the normal range. Once AOA has dropped below the activation point, MCAS will remove the stabilizer increment that it has inserted. If a maneuver to higher AOA is started from a trim point at a lower, more normal AOA, MCAS will run the stabilizer nose down to aid in recovery and then once recovered to lower AOA will run the stabilizer back nose up so that it ends up close to where it started with the airplane back in trim at the condition from which it started the maneuver.

[jimtx]

With correct AOA supplied to the MCAS function, it will begin automatic nose down stabilizer insertion when AOA first exceeds the MCAS activation AOA threshold. The amount of stabilizer motion that MCAS will command is a function of speed and the degree to which AOA exceeds the MCAS activation threshold. The flight deck effect is that the pilot will find that as AOA increases, the airplane has and ever increasing tendency to lower the nose to recover. Keep in mind that the stick shaker will also activate giving the pilot both auditory and tactile cues that AOA is above the normal range. Once AOA has dropped below the activation point, MCAS will remove the stabilizer increment that it has inserted. If a maneuver to higher AOA is started from a trim point at a lower, more normal AOA, MCAS will run the stabilizer nose down to aid in recovery and then once recovered to lower AOA will run the stabilizer back nose up so that it ends up close to where it started with the airplane back in trim at the condition from which it started the maneuver.

What would be the "steep turn" envelope of the MCAS? Would 250KIAS and 45 degree bank trigger it. Or min clean and some other angle of bank?

[CurtainTwitcher]

With correct AOA supplied to the MCAS function,
There is the problem right from the very first assumption, correct AoA data.

I don't think there is any disagreement about the need, intent and function of the MCAS. The issue appears to be this, on the surface its looks like a "quick and dirty" hack to compensate for an issue that cropped up in certification and testing, with the engineering failure mode analysis appearing to be deeply flawed. It was eminently foreseeable that one or both AoA sensors could provide erroneous or missing data due to mechanical or maintenance failure or physically by a birdstrike.

If you look at the Airbus (BTW, not a Bus fanboy, they had their own issues), there is clear guidance to to what happens to the flight controls with failure(s). A good example is the QRH flight control architecture reconfiguration diagram in the QRH, it tells you how the flight control system has reconfigured itself. On the other hand, the MCAS functionality looks to have been buried, with almost no references anywhere, it is almost as if Boeing had gone out of their way to deliberately obscure knowledge of this subsystem. Why? Because we don't want to overwhelm the pilots with information? Really?

Is it mentioned in the engineering manuals anywhere? If the maintenance staff had known about the interconnection between the AoA running the stab forward on it's own, would they have signed it off for a line flight? Was there a warning in the maintenance manual about the consequences of incorrect maintenance of the AoA probe? So many questions about this buried functionality that clearly has deep implications for the safe operations.


Source: Online copy of an old A32x (https://www.scribd.com/document/280744656/QRH-A-pdf) family showing flight control reconfiguration with failure cases. A32x flight controls overview (http://www.dutchops.com/Portfolio_Marcel/Articles/Flight%20Controls/A320_Flight_Controls/A320_Primary_Flight_Controls.html)
https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/924x1530/screen_shot_2018_12_08_at_10_36_12_am_fa683399c314d14d9acad3 3671350a78a71d80c4.png

[hans brinker]

There is the problem right from the very first assumption, correct AoA data.

I don't think there is any disagreement about the need, intent and function of the MCAS. The issue appears to be this, on the surface its looks like a "quick and dirty" hack to compensate for an issue that cropped up in certification and testing, with the engineering failure mode analysis appearing to be deeply flawed. It was eminently foreseeable that one or both AoA sensors could provide erroneous or missing data due to mechanical or maintenance failure or physically by a birdstrike.

If you look at the Airbus (BTW, not a Bus fanboy, they had their own issues), there is clear guidance to to what happens to the flight controls with failure(s). A good example is the QRH flight control architecture reconfiguration diagram in the QRH, it tells you how the flight control system has reconfigured itself. On the other hand, the MCAS functionality looks to have been buried, with almost no references anywhere, it is almost as if Boeing had gone out of their way to deliberately obscure knowledge of this subsystem. Why? Because we don't want to overwhelm the pilots with information? Really?

Is it mentioned in the engineering manuals anywhere? If the maintenance staff had known about the interconnection between the AoA running the stab forward on it's own, would they have signed it off for a line flight? Was there a warning in the maintenance manual about the consequences of incorrect maintenance of the AoA probe? So many questions about this buried functionality that clearly has deep implications for the safe operations.


Source: Online copy of an old A32x (https://www.scribd.com/document/280744656/QRH-A-pdf) family showing flight control reconfiguration with failure cases. A32x flight controls overview (http://www.dutchops.com/Portfolio_Marcel/Articles/Flight%20Controls/A320_Flight_Controls/A320_Primary_Flight_Controls.html)
https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/924x1530/screen_shot_2018_12_08_at_10_36_12_am_fa683399c314d14d9acad3 3671350a78a71d80c4.png
Iberia had a hull loss in Bilbao because below a certain height (not disclosed in the AOM) there was less pitch authority, and they smacked the nose while trying to go around. I think Airbus changed the control inputs afterwards. Just because we have a pretty diagram I don't really trust the bus any better.

[CurtainTwitcher]

We are in fierce agreement hans.

[gums]

Salute!

Be careful, CT, about assuming failure models are straightforward to develop when dealing with software that does more than put nice graphics on your screen or play music. The physical world has its own rules and failure modes. So when a software doofer that can control your physical machine, the failure modes get complicated. Feedback paths can be real tricky, and we are seeing a classic example with this example.

Additionally, the regression diagram for the early AB FBW model presented does not show the various flight control laws that are inhibited or modified or flat out fail. jez saying,

Gums sends..

[Prober]

Pages and pages of discussion have still not satisfactorily explained the problem. It is more and more starting to look like a questionnaire on an application form for the ETPS (with a caveat – do NOT try this until you have done the course).

Maintenance manuals, hidden functionality, include a diagrammatical description of flight control metamorphoses, oh, and remember, if you try to trim manually, the whole process might start again with moved goal posts – and all this whilst struggling with an aircraft which has taken on a mind of its own.

I have been there and done that. The last thing I wanted at the time was to try to read all about it in a book. The why’s and the wherefores are up to the Accident Investigators. A line crew should never have been exposed to this.

Prober

[PPRuNe Towers]

A very, very small pin's head and and angels being crushed to death in the guessing games.

Back when there is more actual data and facts whether from a preliminary report, proper software details from Boeing, or hopefully, CVR data.

Rob

[A0283]

In the search for the CVR Lion Air has hired a professional private company from the Netherlands using the vessel MPV Everest to map/investigate the LKP area. The ship will probably arrive in the area on December 19th.

According to a Lion Air press statement in Bahasa translated with Google.

[MickG0105]

In the search for the CVR Lion Air has hired a professional private company from the Netherlands using the vessel MPV Everest to map/investigate the LKP area. The ship will probably arrive in the area on December 19th.
A professional private company? As the Zen Master said, "We'll see."

Lion Air (and the notion that the airline, rather than the investigative authority, has engaged a search and recovery service is extraordinary in its own right!) has contracted with Maritime Construction Services (MCS), a company that has only been around for only 3 years. MCS has a three page company website and currently operates just one vessel, the MPV Everest. They've had the Everest for less than 12 months. MCS bill themselves as 'an independent Dutch entity and exclusive partner of MRTS Group'. MRTS (Mezhregiontruboprovodstroy) is a Russian subsea construction company specialising in oil and gas pipelines.

Near as I can tell neither MCS or MRTS have ever conducted a subsea search or recovery operation anywhere at any time for anything! The MPV Everest is fitted with a pair of Triton XLX ROVs and a Forum Comanche ROV. None of those ROVs are particularly useful for survey or search work unless they intend to conduct the whole search effort visually; in the context of finding the CVR they're really only useful for conducting visual inspections of previously identified points of interest and some light recovery work. The Everest's apparent only qualification for this sort of operation was that it was handy; it was in Singapore last week. It also has a heavy lift capability not that that is likely to be called upon given the apparent break up of the aircraft on impact.

For the Lion Air 610 contract MCS has announced that they will form a consortium with two local Indonesian companies, Alliance Energy Solutions and PT NADI MARIN SUBSEA. Of that pair, AES is the only one with any sort of subsea sonar search capability via a Kongsberg Hugin AUV.

The whole thing looks like a bugger's muddle to me.

[patplan]

The effort to search for and recover Lion Air PK-LQP's CVR is well underway...


Search for cockpit voice recorder of crashed Lion Air resumes in Indonesia
...A ship equipped with sophisticated technology resumed search for the cockpit voice recorder and the remains of victims of a fatal flight of Lion air JT 610, investigator said here on Thursday...

...A MPV Everest ship operated by a Dutch firm, which is hired by Lion Air, kicked off the search on Thursday morning, said Haryo Satmiko, deputy chairman of the committee.

"The MPV Everest arrived at the crash site on Wednesday night and resumed search this morning," he said.

The mission is undertaken around the clock and will last for ten days. If the mission fails in finding the cockpit voice recorder, a further evaluation will be carried out, Satmiko added.

The fuselage of the aircraft and the remains of 64 victims who have not been recovered would also be the targets of the mission, he said...

Excerpt from from Xinhua news.
===========================================

It's a bit strange - a rather quiet happening- that even local news outlets don't seem to pay any attention to this important undertaking.

[A0283]

During the initial dives that found the fdr memory, the lead diver indicated that the seafloor was covered by a layer of mud of at least 80centimeters. Later 1 meter was mentioned. So they need to have both a clear mapping and a ground/mud penetration capability for that. Does anyone here know what kind of side scan/ multi beam system has that capability, or if there are underwater ground penetration radar systems for such soft toplayers?

If they are not successful this way they might end up having to remove the toplayer. There is some technology development in that field, but... Normal dredging methodologies seem a bit 'rough' for this purpose.

[A0283]

Amazing that the following has not been discussed here and in other pages. This in spite of the reference to Reuters and a number of key players and officials and the fundamental importance to the aerospace of the issues included.

https://www.channelnewsasia.com/news/asia/exclusive--red-tape--funding-problems-hamper-lion-air-black-box-search-11021966

Note: i have made some minir textual changes to improve readability.

December 11, 2018

Bureaucratic wrangling and funding problems have hampered the search for the CVR of the crashed Lion Air jet, prompting investigators to turn to the airline to foot the bill in a rare test of global norms on the probe's independence.

JAKARTA: Bureaucratic wrangling and funding problems have hampered the search for the CVR of the crashed Lion Air jet, prompting investigators to turn to the airline to foot the bill in a rare test of global norms on the probe's independence. Weeks of delays in the search for the CVR may complicate the task of explaining how 189 people died when the Lion Air 737 MAX crashed into the Java Sea on Oct. 29.

Indonesian investigators told Reuters budgetary constraints and the need for approvals had limited efforts to raise the main wreckage and find the CVR, thought to hold vital clues. "We don't have further funds to rent a ship," a source at Indonesia's KNKT said, in reference to specialised equipment needed for the search. "There is no emergency fund for us, because there is no legal basis," the source said, speaking on condition of anonymity. "We have already asked the coordinating minister for the economy, but there is no regulation and it would need to be discussed by parliament," the source added.

The source said Lion Air's insurers had been approached to pay the bill. A source at Lion Air said its insurers had been reluctant to pay for the search and so the airline had stepped in.

The clock is ticking in the hunt for acoustic pings coming from the L3 Technologies Inc CVR fitted to the jet. It has a 90-day beacon, acc to an online brochure from the manufacturer. Safety experts say it is unusual for one of the parties to help fund an investigation. Under UN rules, such probes must be conducted independently to maintain trust in any recommendations made to prevent future accidents. There are also broader concerns about the resources available for such investigations worldwide, coupled with the threat of agencies being dragged into separate legal disputes.

A rare exception was the costly search for black boxes of an Air France jet in the Atlantic in 2009, parts of which were funded by the airline and Airbus after a failed 2-yr effort. The Lion Air jet crashed in relatively shallow water of 30-35 m but only the FDR has been found and the CVR lies among oil pipelines requiring an expensive dynamic-positioning vessel (which does not require anchors).

A Lion Air spokesman said a chartering contract had been signed and a specialised ship would arrive once all international regulatory approvals were obtained. Even though the airline is helping to fund the search, officials from the KNKT will oversee all operations on board.

The CVR could help answer questions over whether the crew responded correctly to potentially faulty sensor data, and any role that a newly modified anti-stall system on the 737 MAX may have played. Lion Air Group co-founder Rusdi Kirana is furious over what he sees as attempts by Boeing to deflect attention from recent design changes, and blame Lion Air for the crash, while the airline faces scrutiny over its maintenance record and pilots' actions. Lion Air CEO Edward Sirait last week said the airline, which has 190 Boeing jets worth US$22 billion at list prices waiting to be delivered, was considering cancelling orders, although no decision had yet been made.

The FDR was recovered 3 days after the crash.

The need for an adequate support ship has been highlighted ever since tests on Nov 12, 2018 suggested the CVR's locator beacon was broken, KNKT head Soerjanto Tjahjono told Reuters. The search requires a heavy-duty supply vessel with a large enough deck and crane capacity to help recover the main fuselage wreckage as well as support a remotely operated underwater vehicle, deputy chief Haryo Satmiko said. He estimated the search would cost about 25 billion rupiah (US$1.73 million) every 10 days and cited the need to obtain "administrative progress" on funding as the main obstacle over the last month.

The Lion Air spokesman referred questions on the funding to insurer Asuransi Tugu Pratama Indonesia, a subsidiary of government-controlled oil company Pertamina.

The insurer was not immediately available for comment.

Finance Minister Sri Mulyani Indrawati said she was not aware of a lack of funding for the CVR search operation.

(US$1 = 14,465.0000 (tel:465.0000) rupiah)

(Reporting by Cindy Silviana; additional reporting by Maikel Jefriando; writing by Jamie Freed; Editing by Tim Hepher and Darren Schuettler)

[Airbubba]

A Wall Street Journal article with a report of faulty 'airspeed sensor' calibration.

Maintenance Lapse Identified as Initial Problem Leading to Lion Air CrashInvestigators zero in on replacement of airspeed sensor in probe of Indonesian airliner’s fatal plungeBy Andy Pasztor in Los Angeles andBen Otto in Jakarta, IndonesiaDec. 25, 2018 7:00 a.m. ET

Crash investigators have concluded preliminarily that improper calibration of an airspeed sensor during maintenance touched off the sequence of events that led to October’s fatal Lion Air jetliner crash in Indonesia, according to people familiar with the details. The conclusion is subject to further analysis, these people said, but it is the firmest indication so far that a suspected maintenance lapse was the initial misstep that ended with the months-old Boeing Co. 737 MAX aircraft plunging into the Java Sea, killing all...

https://www.wsj.com/articles/maintenance-lapse-identified-as-initial-problem-leading-to-lion-air-crash-11545739204 (https://www.wsj.com/articles/maintenance-lapse-identified-as-initial-problem-leading-to-lion-air-crash-11545739204)

[pattern_is_full]

I thought it was an AoA vane (sensor), not pitot. Not that it matters much - bad data confuses "hidden" trim automation > results in strange aircraft behavior in supposedly manual flight > LOCA

[weemonkey]

Really?

What airspeed "sensor" requires "calibration" post fit?

Requires testing, yes.

[FlyXLsa]

This was already posted in Tech Log a few hours ago.

[Ian W]

I thought it was an AoA vane (sensor), not pitot. Not that it matters much - bad data confuses "hidden" trim automation > results in strange aircraft behavior in supposedly manual flight > LOCA
Find a WSJ reporter who understands what an AoA vane is.
I think you will find they meant that the AoA vane was incorrectly calibrated. That would certainly fit with the symptoms of the crash flight.

[Sultan Ismail]

Boeing B*ll Sh*t

They failed to advise the pilot community of the instability of the 737 Max 8

Murder she said!

[BAengineer]

Not sure about the 737MAX but on the 737NG it is not mandatory to carry out a test of the newly installed sensor.

[aterpster]

Not 2018 accident investigation:



Lion Air ends search for CVR from 737 MAX crash | Safety content from ATWOnline (http://m.atwonline.com/safety/lion-air-ends-search-cvr-737-max-crash)

[Zeffy]

Although government agencies typically fund search operations after a crash, the Indonesian Ministry of Transportation said in December it would only fund the investigation process while Lion Air would cover the cost of the CVR search.

In what world does an airline call off the search for critical data relating to one of its own accidents?

Doesn't this development also call into question the integrity and diligence of the Indonesian MOT?

[tdracer]

The search for the CVR isn't ending, but Lion Air will no longer be leading (or presumably paying for) the search.

[flensr]

I'd think Boeing would really want to find it...

[lomapaseo]

Those that want the CVR need to pay for the search

The Governments involved should define the need (Airworthiness)

Curiosity is not always afforable

[Asturias56]

In what world does an airline call off the search for critical data relating to one of its own accidents?

Doesn't this development also call into question the integrity and diligence of the Indonesian MOT?

In Indonesia - the Govt doesn't have much money and so they can only pay so much - right now they're probably prioritizing the Krakatoa tsunami victims who are at least alive - in Indonesia there's always another disaster about to happen that requires funds...................

[aterpster]

In Indonesia - the Govt doesn't have much money and so they can only pay so much - right now they're probably prioritizing the Krakatoa tsunami victims who are at least alive - in Indonesia there's always another disaster about to happen that requires funds...................
Point well taken. Boeing is a VERY important business in the United States. The U.S. government should pony up to continue the search for the CVR, Surely, the executive branch has a "flush fund" for such events (government shutdown notwithstanding), I suspect the chair of the NTSB is quite unhappy, for he is honest and an absolute expert.

[FlyXLsa]

Search for the CVR resumed.
https://uk.reuters.com/article/uk-indonesia-crash-search/indonesia-to-resume-search-for-crashed-lion-air-jets-cockpit-voice-recorder-idUKKCN1P2066

NTSC Continues Lion Air JT-610 CVR Search
http://mediaindonesia.com/read/detail/209161-knkt-lanjutkan-pencarian-cvr-lion-air-jt-610 (https://uk.reuters.com/article/uk-indonesia-crash-search/indonesia-to-resume-search-for-crashed-lion-air-jets-cockpit-voice-recorder-idUKKCN1P2066)
(Google Chrome Translation)
"A KNKT source, speaking on condition of anonymity, told Reuters the team will have seven days using the ship KRI Spica to find the CVR..."

The National Transportation Safety Committee (NTSC) collaborates with the Navy's Hydrographic and Oceanographic Center (Pushidrosal) to return to search for cockpit voice recorders Lion Air JT-610 PK-LQP (CVR) which crashed in Tanjung Karawang waters some time ago.

Pushidrosal deployed KRI Spica-934 which departed from the Jakarta International Container Terminal (JICT) Pier 2, Tanjung Priok Port, Tuesday (1/8).

The departure of the Hydro-Oceanographic survey vessel under the guidance of the Pushidrosal was released by the Head of Regional Police Laksda TNI Harjo Susmoro and the Chair of the NTSC Soerjanto Tjahjono and the main officials of the two institutions.

Kapushidrosal in his written statement, said, the departure of KRI Spica-934 which has underwater equipment with advanced technology is to continue to look for the existence of CVR which until now has not been found with a complete tool such as Multibeam Echosounder (MBES), Sub Bottom Profiling (SBP) , Magnetometer, Side Scan Sonar, ADCP, and HIPAP equipment that can detect signals from the black box of Lion JT-610.

"In addition to the equipment, KRI Spica-934 also brought 55 crew members, 9 NTSC personnel, 18 Navy divers, and 6 Scientists," he said.

Meanwhile, the Chair of the NTSC Soerjanto Tjahjono said that the NTSC requested Pushidrosal's assistance with the latest equipment to look for the CVR's existence.

With all the power available, KRI Spica, which is commanded by Marine Lt. Col. (P) Hengky Iriawan, has time to look for the CVR Lion Air flight number JT-610 for 15 days, given the signal that CVR emits for 90 days.

At present the remaining remaining time is around 15 days left, since the Lion Air plane crashed in Karawang waters on October 29, 2018.

"We will focus on searching 5 x 5 meters wide, around the point where CVR is estimated. With all our efforts and prayers, we hope that the CVR can be found following the discovery of a flight data recorder (FDR) some time ago to complete the investigation into the cause. "The fall of Lion Air is certain," said Kapushidrosal. (OL-1)

[Airbubba]

Reports in Indonesian media that the CVR has been found.

https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/1024x576/si0eu0bvk7kihtpqfn5q_adb237ba9eae2b5b241904b0ccd26391c9e705a 1.jpg

https://kumparan.com/@kumparannews/tni-al-temukan-cvr-lion-air-jt-610-di-kedalaman-38-meter-1547436351341563155

[Airbubba]

An update in English:Lion Air JT-610’s missing cockpit voice recorder found in waters near crash siteBy Coconuts Jakarta (https://coconuts.co/profile/Coconuts%20Jakarta) Jan. 14, 2019

Indonesian authorities this morning found the cockpit voice recorder (CVR), a crucial missing piece in the investigation of Lion Air flight JT-610, which crashed into the Java Sea in October.

The CVR was found in waters off the coast of Karawang, West Java, near the plane’s crash site.

“The CVR of Lion Air JT-610 was found at 09:10 Jakarta time [0210Z - Airbubba], 8 meters below the seafloor, or 30 meters deep,” said Indonesian Navy Spokesman Colonel Liutenant Agung Nugroho this morning, as quoted by (https://news.detik.com/berita/d-4383396/cvr-lion-air-ditemukan-di-kedalaman-30-meter-perairan-karawang)Detik (https://news.detik.com/berita/d-4383396/cvr-lion-air-ditemukan-di-kedalaman-30-meter-perairan-karawang). The CVR is now being transported by boat to an Indonesian Navy base in Pondok Dayung, North Jakarta.

Previously, search parties recovered the plane’s flight data recorder (FDR), which makes up one half of the “black box” — the other being the CVR — both of which may prove crucial in determining the cause of the crash.

The preliminary crash report from Indonesia’s transport safety agency suggested that pilots struggled to control the plane’s anti-stalling system immediately before the crash. Investigators also found that the Lion Air jet should have been grounded over a recurrent technical problem before its final journey, but have not settled on an official cause for the accident.

A lawsuit filed in Chicago blames Boeing for the deadly crash, claiming the manufacturer’s airplane was “unreasonably dangerous.” (https://coconuts.co/jakarta/news/us-lawsuit-blames-lion-air-crash-boeings-dangerous-airplane/)

The Boeing 737 Max jet — one of the world’s newest and most advanced commercial planes — plunged into the Java Sea on October 29 shortly after taking off from capital Jakarta to Pangkal Pinang city, killing all 189 on board. A final crash report is likely to be filed this year.

With additional reporting by AFP

https://coconuts.co/jakarta/news/lion-air-jt-610s-missing-cockpit-voice-recorder-found-waters-near-crash-site/

[Back door]

I am hoping the long salt water immersion didn't ruin the recording(s) and we get to see the transcripts in a timely manner.
Certainly think this will put the spotlight on the failing(s) in this devastating and sad accident.

[tdracer]

I am hoping the long salt water immersion didn't ruin the recording(s) and we get to see the transcripts in a timely manner.
Certainly think this will put the spotlight on the failing(s) in this devastating and sad accident.

I'm pretty confident that the recorder will be just fine. If there is a silver lining to an accident with a brand new aircraft, it's that it has brand new recorders - and the new solid state recorders are vastly better than the older models.
A month or two in ~150 ft. deep salt water is a cake walk compared to what the latest generation of recorders are designed for.

[simon001]

The CVR of Lion Air JT-610 was found at 09:10 Jakarta time [0210Z - Airbubba], 8 meters below the seafloor, or 30 meters deep,” said Indonesian Navy Spokesman Colonel Liutenant Agung Nugroho
Assuming the CVR was in the tail, locating it 8 metres below the seabed reinforces the vertical speed of impact.
Also assuming no beacon signal for weeks, it is pretty impressive that they found it.
I am interested to know how they went about the search.

[YeahYeah]

When I first read the above article, it was mentioned that it was recovered 8 metres below the seafloor. Huh? I thought something was lost in translation. How could it have ever been found under the sea bed. I just read the Associated Press account, and indeed, it was recovered under 8 metres of sea bed mud.
Congratulations indeed to the Navy divers, working in these conditions!

[rog747]

one bit of good news in a very sad story

[atakacs]

I am hoping the long salt water immersion didn't ruin the recording(s) and we get to see the transcripts in a timely manner.
Certainly think this will put the spotlight on the failing(s) in this devastating and sad accident.
Although we know that the Indonesian inquiry is pretty "leaky" there is no reason why transcripts should be put into the public in a "timely manner".
Congrats to the divers for what seems to be a fairly complex recovery. Details would be indeed most interesting.

[Volume]

there is no reason why transcripts should be put into the public in a "timely manner".
ICAO Annex 13 might be a good reason... The next intermediate report should at least contain the main aspects of the CVR recordings, if not a transcript of the most important conversation.
It is not unusual to publish the raw transscript pretty quickly, often minus the famous last words which do no longer contribute to understanding the accident.

[Derfred]

A KNKT source, speaking on condition of anonymity, told Reuters the team will have seven days using the ship KRI Spica to find the CVR..."

The National Transportation Safety Committee (NTSC) collaborates with the Navy's Hydrographic and Oceanographic Center (Pushidrosal) to return to search for cockpit voice recorders Lion Air JT-610 PK-LQP (CVR) which crashed in Tanjung Karawang waters some time ago.

Pushidrosal deployed KRI Spica-934 which departed from the Jakarta International Container Terminal (JICT) Pier 2, Tanjung Priok Port, Tuesday (1/8).

Wow, that’s amazing. They’ve been searching for nearly 3 months and this mob found it in a week! Well done!

[Luc Lion]

Apologies if this has already been posted above ; I found nothing through a quick search.
Here is the report on a Falcon 7X serious incident in May 2011.
https://www.bea.aero/uploads/tx_elydbrapports/hb-n110525.en_01.pdf

I think that the serious incident of HB-JFN shares several commonalities with the Lion Air accident:
1. In both cases, an uncommanded movement of the THS has led to a catastrophic situation.
2. In both cases, the uncommanded movement has been caused by the failure of a single element in an automation system controlling the THS.
3. In both cases, the automation system was a new design or a redesign.

The report does a good job of showing that the combination of 14 CFR 25.671 and 14 CFR 25.1309 implies that an automation system that has the potential of commanding a THS runaway should be designed as fail-safe, which implies immunity to single element failure, or should provide appropriate warning to alert the crew of the unsafe operating situation. The warnings must be designed to minimize crew errors which could create additional hazards.
That was not adhered to by the Falcon 7X at the time of the serious incident and, obviously, also by the B737 Max at present time.

The report does also a good job of showing that the non-compliance to certification specifications was partially caused by a botched risk analysis process and that the risk analysis failure has systemic causes.
I wouldn't be surprised if similar risk analysis failures would be found at Boeing in the context of the Lion Air accident investigation.

Another thing I noticed in the HB-JFN incident report is that one of the first reactions of Dassault had been to add a button in the cockpit that disables the auto-trim system and enables the electric trim push buttons available to the pilots.

Luc

[VH DSJ]

Avherald is reporting that the Indonesian NTSC (KNKT) has successfully downloaded the CVR with over 2 hours of audio in good condition. It is currently being transcribed. Hopefully it will soon be made public or be leaked out on social or mainstream media.

(Note to mods: I can't post on the previous thread of this accident because it is locked.)

[TowerDog]

Avherald is reporting that the Indonesian NTSC (KNKT) has successfully downloaded the CVR with over 2 hours of audio in good condition. It is currently being transcribed. Hopefully it will soon be made public or be leaked out on social or mainstream media.

(Note to mods: I can't post on the previous thread of this accident because it is locked.)

Hopefully it will soon be made public? :sad:

[aterpster]

We'll have to wait until the final report:

https://tinyurl.com/yb66gajt

[Asturias56]

Sounds like sense for once - it'll save 70000 posts on here

[Machinbird]

The recording needs to be filtered first due to “background sounds” hindering the transcription, said Soerjanto Tjahjono, the chief of the transportation safety committee (KNKT).“It might take one or two weeks because it was noisy inside (the cockpit),” he told Reuters.
Those stick shakers can be rather noisy.:{ It was likely very hard to communicate in that cockpit as well.

[Octane]

https://www.nytimes.com/2019/02/03/world/asia/lion-air-plane-crash-pilots.html?action=click&module=Top%20Stories&pgtype=Homepage

[lomapaseo]

yet another speculation to capture readership.

[jimtx]

It would be interesting to know how Brazilian carrier Goa trains it's pilots on MCAS. I seem to recall it being a low level item requiring CBT or something like that.

[Roger_Murdock]

yet another speculation to capture readership.

What exactly do you take issue with in the article? It seems to be a good factual summary for a general public audience of the part of the investigation focusing on MCAS. It does not assign blame or make final conclusions about the accident.

[Carbon Bootprint]

yet another speculation to capture readership.
If it was the New York Post, I might agree without further question. But why do you say this?

I seldom agree with the Times on politics, but when they want to do some serious reporting they're generally amongst the best. Is there anything here that hasn't already been mentioned and/or supported in the main LionAir crash thread? If so, can you enlighten us?

(OK, I see Mr. Murdock has similar concerns but managed to slip in ahead of me.)

[Carbon Bootprint]

It would be interesting to know how Brazilian carrier Goa trains it's pilots on MCAS. I seem to recall it being a low level item requiring CBT or something like that.
Are you talking about GOL? Goa is a Portuguese enclave in India, but I'm not familiar with them as a Brazilian operator.

[jimtx]

Are you talking about GOL? Goa is a Portuguese enclave in India, but I'm not familiar with them as a Brazilian operator.

Yep, GOL, brainfart.

[Super VC-10]

The original thread is closed.

https://www.pprune.org/rumours-news/614857-indonesian-aircraft-missing-off-jakarta.html

The KNKT have released their final report into the accident.

http://knkt.dephub.go.id/knkt/ntsc_aviation/baru/2018%20-%20035%20-%20PK-LQP%20Final%20Report.pdf

[shimin]

Scare factor should be taken into account in future system design and evaluation。