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Indonesian aircraft missing off Jakarta

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Indonesian aircraft missing off Jakarta

Old 1st Nov 2018, 22:54
  #421 (permalink)  
 
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Trim Wheel

Canít you just grab the trim wheel and immobilize it if necessary?
Seems to me that was the case in Mr Boeingís KC-135.
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Old 1st Nov 2018, 23:05
  #422 (permalink)  
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"I also am concerned that STS as an automated system that uses airspeed as an input could work against the pilot. I note in the training video above the trim wheel merrily spinning back and forth uncommanded after AP and AT disengaged. Can STS be disabled? should it be? for uas_""

Can be disabled immediately by a quick blip on the pitch trim.

Canít you just grab the trim wheel and immobilize it if necessary?"

No, it is very powerful
"


Regards
Exeng
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Old 1st Nov 2018, 23:08
  #423 (permalink)  
 
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Originally Posted by TangoAlphad View Post
Modern Jet pilots are more and more reliant on what is inside. I often see 'visual approaches' almost entirely flown head inside following the ILS indications. It is sad (and deeply concerning) but I can honestly imagine a pilot on a cavok day trying to cross compare and make sense of instrumentation and ignoring what is outside entirely.
Absolutely true, next time you fly as PNF or on the jump seat take a look at the PF and where he is looking, I have even had the call 'Glideslope' from the PNF and we were almost in the flare.. One other point is the use of headsets, Most if not all the 'old' brigade which includes me have one ear uncovered. The complete opposite is true of the 'new' brigade. On top of this some headsets have noise cancelling features, so with 2 ears covered and noise cancelling on, you are now completely immune to the surrounding noise. I tried it once and was most disorienting. The book Vulcan 607 of the bomber raid during the Falklands war, mentions an UAS incident. The Capt when going for some rest mentions to the co-pilot to watch the speed. The speed was decaying so the aircraft was put into a dive, the copilot quickly realised the noise levels were too high for the indicated speed. The pitots, were frozen, UAS checklist carried out and the aircraft continued to Ascension. My point is, keep one ear open and look out the window.
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Old 1st Nov 2018, 23:46
  #424 (permalink)  
 
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Salute!

Guess we are heading toward a sub-thread about the "STS" and all the concerns about how much automation you can handle and how to revert to manual flying unless in an Airbus.

And then there's all the "sub-modes", the reversion sequences, what is working versus what is not, and so forth.

The Boeing is not an Airbus with 100% fly by wire. But it appears that a few systems have "help" from HAL..
And the STS is one

Looks like the STS implementation feeds back to the controls to provide some kinda force feedback. Wonderful. But if that system is corrupted, then you might feel something the opposite of what the aero conditions are normally telling you.

For now, I am sticking with a combo of erroneous air data and a mechanical problem with the stab.

Gums opines...
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Old 2nd Nov 2018, 00:03
  #425 (permalink)  
 
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Originally Posted by Mad Flt Scientist
So a design solution applied is to have an automatic system act to increase the required force - to introduce a degree of "artificial stability" in effect. One way to do this is to have the aircraft automatically "trim the wrong way". that way, when hand flying (and not trimming) you find you have to pull more to slow down (part of the pull is the natural pull the aircraft requires, part is to fight the opposite auto-trim), and similarly push more to accelerate.

Unfortunately these systems are often called things like "auto trim" or have "trim" in their name, and that leads people to sometimes think that their intention is to HELP the pilot trim the a/c, whereas they are designed to do the exact opposite.
Interesting. I've never flown an aeroplane with STS or similar, but I would imagine seeing and listening to the trim wheel spinning of it's own accord, when I'm hand-flying, would be disconcerting. I wonder how it's designed to/does operate during an Unreliable Airspeed event...
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Old 2nd Nov 2018, 00:33
  #426 (permalink)  
 
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It is interesting to consider that a contributing factor to this accident may have been the Boeing (vs Airbus) approach to introducing automation into the cockpit. Both the STS and elevator feel systems are provided to make the retained Boeing yoke feel (in some flight modes) as if you are flying a simple manual and longitudinally stable aircraft, with assigned stick force per G, and apparent aerodynamic feedback through the controls.

It seems questionable to me if these systems are coded to continue at all in the UAS condition, as they will substantially increase workload and the chance of catastrophic upset if they are being fed with bad airspeed data. The elevator feel system (which just applies force at the yoke) will be quite unhelpful, but the STS is worse as it is physically altering the horiz stab incidence. It doesn't seem hard to imagine that although most experienced but automation-centric crews will not be overwhelmed dealing with the UAS with these additional challenges (as appeared to occur in the flight before the accident), some may leading to catastrophic upset (possible explanation for this flight).
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Old 2nd Nov 2018, 00:38
  #427 (permalink)  
 
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Is it possible that the STS, given an (incorrect, too-slow) air-speed, after the AP was disengaged (perhaps because AC noticed the conflicting AIS and is following the QRH)....might then trim nose-down to compensate for the erroneous low airspeed? It does seem from the info thus far that there was a fairly abrupt nose-down shortly after TO?

If so that must be stressful for AC...?
Can STS be disengaged just like AP or AT?

Just wondering how much the pilots might have had to work against STS

Well,youre into engineering territory but from a pilots perspective....yes,STS(manual flight) just like AP stabilizer trim(automation engaged) would exacerbate an already bad UAS event.FCC controls both STS and AP stab trim and it gets CAS,AoA,IVSI from ADIRU as well as engine N1 from DEU and flap position from FSEU.If speed sensed is low it commands trim down providing certain parameters are met:a)airborne more than 10 seconds b)AP not engaged c)can not oppose pilot commands(ie if the pilot is pulling on the column it wont trim down) d)pilot hasnt operated electrical main trim in the last 5 seconds etc etc
If the ADIRU input of CAS to the FCC is corrupted,you will get the "wrong" trim.This explains the write up of the previous flights commander who reported STS trimming the "wrong way".So if the CAS sensed is low(ASI is under-reading in a climb due static vent blocked) then it will trim down.In reality the speed/AoA is not low at all so the trim is opposite of what is required.Every time the pilot pulls on the column to counteract the unwanted trim the STS cuts out but it will trim again if back pressure is released.This would explain the rollercoaster effect.Similarly,if you are climbing in icing conditions with automation engaged and the pitots ice up,the AP stabilizer will start to trim up to counteract the sensed CAS (ASI overreads in a climb with blocked pitot).If it goes unnoticed by the pilots,it could be very dangerous.
To disable STS you would place the AP stab trim cutout switch to CUTOUT.This is not mentioned in any NNC or FCOM.
The commander of the previous flight got the plane back safely at FL280(non RVSM).Maybe this is because they disabled AP stab trim during trouble-shooting and were naturally reluctant to reinstate it .He may have got the FO to hand fly home below RVSM airspace with AP stab trim in cutout I dont know.
Only one FCC sends the STS signal.On power up it is FCC A .If power remains to the FCCs during turnaround,the squat switch will send a signal to change it to FCC B for next flight.If power is interrupted during turnaround,FCC A will command the STS signal for the next flight too.
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Old 2nd Nov 2018, 01:12
  #428 (permalink)  
 
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Originally Posted by Machinbird View Post
Canít you just grab the trim wheel and immobilize it if necessary?
Seems to me that was the case in Mr Boeingís KC-135.
Yes, you can.
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Old 2nd Nov 2018, 02:34
  #429 (permalink)  
 
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Good points Rananim. The one issue I see here is with your more complex airspeed unreliable scenario with STS trim involvement is that you need to recognise that there is a linkage between the two, and then do the "Runaway Stabilizer Trim" memory items in addition (should have already covered the initial items in the Airspeed Unreliable initial memory items, Autopilot Off, Autothrottle Off),then Stab Trim Cutout switches (both) cutout, and you are back to a "plain vanilla" (not to diminish the degree of difficulty) airspeed unreliable.

Similar to the windshear escape, it helps to "blip" the trim every couple of seconds so you aren't wrestling the trim during the escape.
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Old 2nd Nov 2018, 02:41
  #430 (permalink)  
 
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Originally Posted by rh2600 View Post
Apparently, we're not the only ones trying to figure out if its the FDR or CVR - just heard on Radio NZ that "the authorities now say they are not sure if its the the CVR or FDR"
On this video they show recovery of the MU, however I wonder what was in hand of 1st diver? Maybe someone could translate what they are talking about in local language...
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Old 2nd Nov 2018, 03:28
  #431 (permalink)  
 
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Originally Posted by bobdxb View Post
On this video they show recovery of the MU, however I wonder what was in hand of 1st diver? Maybe someone could translate what they are talking about in local language...
Looks like some diving tool

get (the basket) close (next to the divers)
dont throw (that thing)
(after the black box slipped in)
itís quite heavy, let the water spoil a little bit
be careful , donít fall
(someone fell to the sea to push the basket from bottom)
step aside
(Please) make a report

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Old 2nd Nov 2018, 03:48
  #432 (permalink)  
 
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Originally Posted by bobdxb View Post
On this video they show recovery of the MU, however I wonder what was in hand of 1st diver? Maybe someone could translate what they are talking about in local language...
The object was an underwater LED flashlight.
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Old 2nd Nov 2018, 05:33
  #433 (permalink)  
 
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My God, what a nonsense (unless it was meant as a joke)
There was a test pilot of a GA manufacturer who wrote how he used a weight hanging from the overhead by means of a piece of string as a back up attitude indicator. There is a thread running in Rotorheads at the moment that includes examples of nonsense taught in sims by professional trainers, so don't be surprised what you come across anywhere.
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Old 2nd Nov 2018, 06:49
  #434 (permalink)  
 
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Originally Posted by bobdxb View Post
On this video they show recovery of the MU, however I wonder what was in hand of 1st diver? Maybe someone could translate what they are talking about in local language...
According to my Indonesian wife, it's not very interesting.
Basically - we found this black box, I think it's important, be careful with it, we should report this right away...
Like I said, nothing special...
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Old 2nd Nov 2018, 07:35
  #435 (permalink)  
 
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Aviation Herald Report

On Nov 1st 2018 the airline confirmed one of their maintenance engineers was on board of the aircraft during the accident flight. This was an "anticipatory measure" in the event of technical problems with the new aircraft. As such, "the presence of the technician has nothing to do with the condition of the aircraft before taking off."
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Old 2nd Nov 2018, 08:16
  #436 (permalink)  
 
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Originally Posted by sSquares View Post
On Nov 1st 2018 the airline confirmed one of their maintenance engineers was on board of the aircraft during the accident flight. This was an "anticipatory measure" in the event of technical problems with the new aircraft. As such, "the presence of the technician has nothing to do with the condition of the aircraft before taking off."
The 737 Max in question had been in service for 11 weeks. Another 10 of the type are flying with the airline, with the first having been delivered in the middle of last year. So hardly a "new aircraft" or type.

Yes, it's not unknown for airlines to carry a flying spanner on a route where there's no engineering support at the far end, but on a route that has 6 daily rotations it's hard to believe that's the reason either..
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Old 2nd Nov 2018, 09:27
  #437 (permalink)  
 
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FDR or CVR?

Should be no problem to id the recovered item. The attached cylindrical item (that looks like a grab handle) is the Underwater Locator Device. (Pinger).
It has a unique serial number and expiry date. The aircraft's delivery docs will show which unit had that ULD attached at Boeing prior to delivery.
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Old 2nd Nov 2018, 10:00
  #438 (permalink)  
 
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Originally Posted by tdracer View Post
According to my Indonesian wife, it's not very interesting.
Basically - we found this black box, I think it's important, be careful with it, we should report this right away...
Like I said, nothing special...
https://www.merdeka.com/peristiwa/bp...300-meter.html (translated with google)

Head of Marine Technology and Survey Center for Technology Application Assessment Agency (BPPT) M Ilyas is optimistic the team will find CVR. He estimates that the distance between the FDR and CVR is not far from the sea.

"It is approximately 200-300 meters, not too far from (CVR)," he said at the Jakarta International Container Terminal II Basarnas Post , Tanjung Priok, North Jakarta, Thursday (1/11).

Ilyas said, in fact we ship BPPT to have captured two ping locater signals from FDR and CVR. However, BPPT ships must move locations because many scattered fragments are captured by ship sonar scans. So you have to sail to the rubble which is suspected to have CVR instructions.

Pertamina's pipes and strong currents under the sea are also obstacles. So, said Ilyas, the team had difficulty removing the anchor and could not reduce the Remote Operated Vehicle (ROV) or underwater robot technology to look for objects.

"The obstacle is that there is a Pertamina pipeline. So that we cannot anchor our ships there to do more detailed ROV. We have to be outside about 550 meters from that location to carry out this ROV operation with the difficulty of the current being very strong there , "he said.

He said, the CVR could last for 30 days starting from the plane falling. The signals sent by FDR and CVR are also very strong, because Lion Air PK-LQP is a new aircraft.

"So the shipment is fast, ping ping is like that. So it is heard (ear) it is a bit different from the other signals. Just because there are many dives today, many ships operate so we have a lot of errors, lots of noise" he explained
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Old 2nd Nov 2018, 10:16
  #439 (permalink)  
 
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Tempo(dot)Co report on ATC Transcirpt

Stated in the report that the transcript was not verified. Some correlation to previous theories posted here.

Lion Air pilot Bhavye Suneja asked his airspeed to the ATC after experiencing a technical issue less than two minutes after take-off at 06:21.53.

The pilotís request to change altitude to 5,000 feet was approved by ATC and was requested to maintain altitude at 06:24.58. During this exchange, Bhavye asked the ATC to confirm the planeís airspeed to which the ATC answered 332 knots.

at 06:29 the ATC saw Lion Air JT 610 left 5,000 feet followed by the Bhavye communicating to the ATC upon a problem with the planeís flight control and asked for his plane to be given 3,000 feet separation with other aircraft in his airspace.

at 06:32, ATC asked the pilot whether Bhavye was ready to land again at Soekarno-Hatta, but the pilot did not answer and seconds after, Lion Air flight JT 610 vanished from the ATCís radar.

flight data recorder (FDR) from the planeís wreckage submerged under the seabed just 500 meters from its last contact with ATC.


Suggested UAS followed by flight control problem.
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Old 2nd Nov 2018, 12:13
  #440 (permalink)  
 
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CVR

"He said, the CVR could last for 30 days starting from the plane falling. The signals sent by FDR and CVR are also very strong, because Lion Air PK-LQP is a new aircraft."

Just small correction, the CVR and the FDR underwater locator beacons could last for 90 days starting from the plane falling.​​​​​
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