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737-500 missing in Indonesia

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737-500 missing in Indonesia

Old 12th Feb 2021, 06:08
  #581 (permalink)  
fdr
 
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Originally Posted by tdracer View Post
ll, the T/R is a non-sequitur in this discussion.
..
No argument, If anything, that would have ensured some detection by the crew of the problem.


tdracer

It's always interesting to go over a CVR, at least for the spectral data, and the level of confusion that arises. IOn this case, however, much like CI140 or even GF172, or Flash 604, what happened leads to a relatively small number of causations. Once instrumentation error such as AI855, KAL 8509, etc has been discounted, and where a flight control has not been compromised (maybe arguably XL888T... through the flight test procedure followed by the crew) possibly still Flash 604 [according to the official report... according to the flight data, nope, it was not a technical defect, full flight control authority existed in the "recovery" which report disregards], thereafter, UAs result from a loss of SA. There are myriad manners to lose SA, and we are all susceptible to loss of SA, generally being human, and we have inertia in our processes that make it time-consuming to recover SA if we actually do recognize a loss.

I do hope they find the bits of the CVR, but I suspect that the insight it provides will be confirmatory rather than a revellation. Would prefer that the industry not undertake canned UA training, that it be done in conjunction with normal flight profile training, to address the deficiencies we have in SA in our community. To that end, if TM's or CP's want to PM me, I am happy to propose various scenarios that can be introduced into a normal flight to give real-world SA training value to the crews. Patently, UA training as done today doesn't do a great job., in fact, paradoxically the current training may give some adverse levels of confidence to the system, "...we have ticked that box so it's done and dusted, let's get on with the next agenda item..." The MAY in that is just a curiosity, a study into the efficacy of existing UA training would be hard to quantify.

Within the community, we have a problem across all countries, languages, and religions, that crews don't pick up the cues of anomalies developing. dumping a 777 on its belly, an engine fire in reverse following a FOHE failure... 263 kt approaches (not an F-104) parking in the water short of the runway, pulling the att system platforms in IMC, basically all of the stuff we do frequently and apparently irreducibly. The G/As that end up with some 55-60 deg nose up, at low speed and a prompt youtube image thereafter. We spend our time in the sim ticking matrix boxes on instrument approaches we do every day and fail to train on SA loss, recognition, and recovery. One can argue that the engineering and certification of the MAX was an SA failure, it was just in the world of MEDA, and DERs, and ODA/DOAs. Certainly in the cockpit as well, irrespective of the fact that the crew had no information on the matter at hand or not. The human goes one way, the world goes the other and it ends in tears. How about we start training SA properly.

On APLT disconnect, automatic disconnect requires reaching the limit torque of the servo for 10 seconds to trigger the automatic disconnect.

Last edited by fdr; 12th Feb 2021 at 13:59. Reason: Flash 604 comment
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Old 12th Feb 2021, 09:32
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Correction

QDM360

I previously referred to post 519 as a credible source for a translated version of the initial report.

Having now read the English version of the official report, THERE IS NO REFERENCE WHATSOEVER to an un-commanded A/T activation during the takeoff.

My apologies.
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Old 12th Feb 2021, 13:38
  #583 (permalink)  
 
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tdracer

I'm not sure why "throttle snatcher" got into this discussion. The implication to me is that it would have been obvious to any pilot.
But wan't Tarom which you referred to as an example a slipping or slow reduction while in a high workload (and the degree of pilot incapacitation challenged).
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Old 12th Feb 2021, 14:10
  #584 (permalink)  
 
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For the people saying that "it can happen everywhere", while true, it's not statistically relevant. Having operated in those region for a few years I can tell you that there is a reason this events keep happening there, but for political correctness I can't explain the why's and how's, but if you haven't operated there, you just don't know and you can't generalize it as a global problem, because the statistics in Indonesia paint a very clear picture and people refusing to see it are part of the problem.
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Old 12th Feb 2021, 14:44
  #585 (permalink)  

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Irrespective of what part of the world you are talking about, the quality and style of the basic training at flight school sows the seeds for the embryonic pilot.

Whilst instrument flying is a major part in what is taught prior to multi-crew flying, being comfortable “turning an aircraft onto its back” is part of the development needed to expand the SA capability of student pilots.

Limiting the basic non IF flying training to steep turns and stalling, together with the EASA 5 hour UPRT package, to “tick the box” is not the solution to prevent this type of tragic accident in the future.

Whilst EASA recognise the need to improve SA, it must be only a temporary measure until a more robust training syllabus is adopted.

And yes, it will cost more, but compare that to the price of this style of accident, not only in momentary terms for the beancounters, but the human suffering which inevitably occurs as well.
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Old 12th Feb 2021, 15:00
  #586 (permalink)  
 
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parkfell, I agree - getting used to being upside down and then having the bottom fall out of your world - all on limited panel instruments - is the good basic training that lives with you for the rest of your days. It helps with the 'startle effect'. Then, after that, you need regular top-ups of basic instrument flying to maintain the scan and situational awareness.

fdr, In an earler post, you mentioned something about the kinds of SA training you would like to see rather than the current ticks in boxes. Rather than a PM, could you share your ideas with us all please.
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Old 12th Feb 2021, 15:56
  #587 (permalink)  
 
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Even though this tread is creeping I'm helping the centipede with a two penny worth.. when we "teach JU" we are really just teaching recovery FROM unusual attitudes, not UPSET per se. The Unusual attitude assumes we have somehow mismanaged the aircraft and ended up exceeding the acceptable limits, thus we are now "recognising upset" and recovering. What is more difficult to teach or indeed demonstrate is the Upset caused by External factors such as flying through the bottom of a CB, Mountain Waves etc etc or indeed an Upset induced by poor handling of a system failure.
The brain has limited diagnosis capacity and tends to try to put the aircraft in a dynamically stable sate before recognising why it is unstable to start with, our teachings say nose low..do this... nose high...do this.. high bank... do this... Which is all well and good if you have recognised the influence that put you there in the first place.
We have limited time in the sim and it's basically about threat and error management within the training budget and capacity of the crew, an old lag Captain may be cool as cucumber but is newly typed FO is sitting like a rabbit with eyes in headlights and in this scenario "advanced training" becomes of limited value as the new FO has no capacity left for CRM or fault diagnosis.
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Old 12th Feb 2021, 16:17
  #588 (permalink)  
 
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As a simple ppl I have a question that baffles me, The FDR shows a bank up to 45 degrees after AP disengage but no corrective aileron applied, If I fly through a lumpy bit of air and one wing suddenly drops it is automatic or instinctive to immediately apply opposite aileron, no need to think about it it just happens so what stopped the pilot in this incident doing what should be automatic?
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Old 12th Feb 2021, 16:45
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I would like to think that any pilot worth their salt would immediately grab the controls to level the aircraft. As you say, this should be instinctive and automatic - no thinking required.

I wonder if PF got too closely involved with avoiding CBs and just did not notice the increasing thrust lever and N1 split and the increasing bank on the yokes? If both PF and PM were concentrating on the weather radar and looking out to avoid and find a path between CBs; maybe the increasing asymmetric situation was simply not noticed. Then with no warning, the auto-pilot suddenly drops out and the aircraft rapidly banks over..............
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Old 12th Feb 2021, 17:50
  #590 (permalink)  
 
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From translations of a briefing conducted Wed 2021.02.10 by Captain Nurcahyo Utomo, Chairman of the KNKT Aviation Accident Investigation SubCommittee.
.
KNKT Has Predicted the Location of CVR Sriwijaya Air SJ 182, Allegedly Buried in Mud
By Fitria Chusna Farisa
Kompas 2021.02.10

Excerpts
- Search efforts to locate the CVR memory module continue.
- Attention is concentrated in a 25m x 25m region where the beacons, FDR and fragments of CVR were found previously on or near the surface of the sea bed.
- Now teams are digging below the surface, working 5m x 6m sections of a matrix at a time. A "mud blower" was introduced on the 9th to complement manual excavation.
- Inclement weather is impeding progress. Not only are wind, waves and rain factors at the immediate search site, flooding on an adjacent island has triggered such severe runoff of muddy water that sediment from the runoff is impairing underwater visibility at the crash site.
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Old 12th Feb 2021, 17:51
  #591 (permalink)  
 
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jodeliste

In the absence (until the final report) of an FDR trace, we have no knowledge of the bank angle or control inputs after it had passed 45°.
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Old 12th Feb 2021, 20:46
  #592 (permalink)  

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Jodeliste

I share your concern as to why no manual corrective action was taken following A/P disconnect. No.1 task : fly the aircraft (aviate)
I am assuming pilot incapacitation was not a factor.
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Old 13th Feb 2021, 03:09
  #593 (permalink)  
 
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Unfortunately my memory of this isn't very good (I never had much involvement with the 737, so didn't pay as close of attention to the discussions as I might have). But after the China Southern 3943 crash (one thrust lever stalled at idle, resultant thrust asymmetry resulted in a loss of control and crash), Boeing did come up with a warning that there was excessive thrust asymmetry with the autothrottle active (I was on the Boeing Propulsion Safety Committee and it was discussed during at least one of our meetings). I don't recall the detains of how it worked or what it did, but I had assumed that - having contributed to a crash - it would be fitted fleet wide (by AD if necessary). For whatever reason, it apparently wasn't...
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Old 13th Feb 2021, 08:40
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I always thought that on the B737 Boeing kept the big clunky control column , clattering trim wheel and oversized moving throttles for a reason.
That is that you don’t need a warning system. Its in your face.
In most of the UAs , SA problems described above crews have watched on while things get clearly out of shape.
How you train to mitigate against that in already full training schedules I don’t know.
But I do know that when I have seen these scenarios repeated in the sim. the instructors input is usually
“ Don’t disconnect now , let it fully develop”
How do you manufacture airmanship ?
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Old 13th Feb 2021, 09:39
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It's an unfortunate game we have to play in the sim. Your immediate reaction is to fix it, but if you fix it too early, you miss the "good bit" of the training exercise. I certainly hope we don't have people flying around who leave the sim not knowing which parts were done purely for demonstration/training.
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Old 13th Feb 2021, 10:07
  #596 (permalink)  
 
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jodeliste

You’d think so, would’t you? When I first started flying my first multi-crew airliner (an ATR), having come from a single pilot IFR operation a basic aircraft, we were in the hold and hit what I think was a bit of wake turbulence (on autopilot.) We had a sharp wing-drop. As First Officer, Pilot Monitoring, I was a little bemused when the Captain’s response was to grab the overhead grab-handle and stare wild-eyed at the PFD! I quietly just hovered near the control column, but then we recovered to wings level.
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Old 13th Feb 2021, 11:27
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Hi Jodeliste,
But as far as we guess it already had full autopilot opposite aileron. Thus aileron alone cannot be manually made to go even more.

[As our learned friends have been explaining, rudder and throttle plus elevator and believing the instruments when upset, are one's tools.]

With all those poor folk dead it's not a light discusssion here.
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Old 13th Feb 2021, 12:25
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The autopilot has limited aileron authority compared to manual input. The following AAIB report states:

Enquiries of the manufacturer revealed that the maximum roll control deflection which the autopilot can achieve is, by design, about 4.5° of aileron movement (a control wheel movement of about 20°), depending on the stimulus. The maximum aileron movement which can be achieved by the pilot is about 20°, which requires a control wheel input of about 82°.
AAIB Bulletin No: 2/97 Ref: EW/C96/9/3 Category: 1.1
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Old 13th Feb 2021, 13:01
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Very interesting.
We have heard here that the crew should have noticed the large control wheel movement before the AP disconnected.
The aircraft was supposed to turn right in the timeframe just before the upset. Therefore the crew would expect some amount of right control wheel movement.
I don't know the speed at which the AP put in right aileron, ie how long time passed between say 10 degrees right control wheel position and reaching 20 degrees limit position?
Should a 10 degree right control wheel position raise any alarm from the pilots when the pilots expected some level of right control wheel movement due to right turn put into the AP? If no, how much movement should raise an alarm? How long time would pass from the "alarm threshold" position until AP disconnect?
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Old 13th Feb 2021, 13:15
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mikehallam

I thought it was the AP disconnecting that initiated the roll as the AP aileron input disappeared when it disconnected. so it could have been replaced manually by the pilot
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