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737-500 missing in Indonesia

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737-500 missing in Indonesia

Old 10th Feb 2021, 17:37
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Uplinker

Disagree. Less automation. A “better” system will fail in a new and improved way.

Autothrust predates me, but I’m sure when it was introduced, there was a laundry list of things it helped with. Now we’re seeing problems it causes when it doesn’t work exactly as advertised.

Why wasn’t the rudder controlled by the pilot?
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Old 10th Feb 2021, 19:55
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The issue is the inability of pilots to fly the airplane up to cruise altitude, trimming everything up, and THEN, turning on the automatics to see if they actually work. If the pilots cannot do that, then they belong back in seat 28D and 28E instead of 0A and 0B.
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Old 10th Feb 2021, 20:11
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Originally Posted by Teddy Robinson View Post
it retards a TL during the takeoff ....
This was mentioned multiple times now - but is not backed up by the report. The report first mentions the TLs to diverge while climbing through 8150ft. Nothing unusal is mentioned for the takeoff.
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Old 10th Feb 2021, 22:12
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Back in the old day, having staggered thrust levers wasn’t unusual, particularly on 4 engined types. Whilst this is an older generation of aircraft, the accident lends weight to the Airbus philosophy of fixed lever positions and not having the levers move by themselves.

Crew competence seems to be the main factor here, the ability to recognise that a system wasn’t performing correctly and take appropriate action was lacking.
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Old 10th Feb 2021, 23:06
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On the contrary. While it looks like the A/T malfunctioned in a fairly strange way, the thrust lever angle seemed to correspond to engine thrust output and the tactile/visual feedback in form of the moving thrust lever was still there.
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Old 11th Feb 2021, 00:19
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In an Airbus, the levers would have been in the climb detent and would not have moved of their own accord.

The whole think is an example of the Swiss cheese model or accident chain:

1. If the system had been repaired correctly.
2. If the crew had recognised the problem and taken appropriate action.
3. If the crew been able to cope with the unusual attitude the aircraft got into.

A layer would have stopped the hole forming or broken the chain and it wouldn’t have happened.
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Old 11th Feb 2021, 01:08
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If only they would have identified the asymmetric flight the aircraft was in, than a gentle rudder input would have given them all the time in the world to figure out what was the problem, as autopilot would have remained engaged.

I do hope CVR is found, so it can shed some light on the crew's perception of the events.
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Old 11th Feb 2021, 03:12
  #548 (permalink)  
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FlyingStone

Hmmm, conflicted on the need for the CVR to shed light.

Res ipsa loquitur.

Plane goes from sunny side up to zero in ~20 seconds. Required flight path has a roll. FDR is indicated to show a throttle split. The physics of what needed to happen is straightforward. The CVR would arguably add insight into the human interactions, as well as adding additional physics data points, automated alerts etc. On the other hand, the CVR will likely show the level of confusion that arises in a crew's comprehension of the events, but this tune has been played before, repeatedly, AF 447, Adam 574, AS214, Perpignan (XL888T), CAL140, CAL676, IA605 (Bangalore) etc. In all of these sorts of cases, the crews were dealing with trying to catch up to what the aircraft was actually doing, vs their expectation of state. Other cases such as AI855, KAL 8509, and similar are cases where the information to the crew has failed and the crew don't react in time to resolve the differences. This is not a TE901 type investigation as to WITWHH. The facts speak for themselves. CVR's have a paradoxical impact, that it becomes easy to dismiss the crew as being exceptions, rather than the generic run of the mill mix of aluminum tube importers/exporters. The recommendations will almost certainly add a need for better training, but of what? Of being human, of the time to recognize that things just ain't so? To open up a NNCL that takes 20 seconds to find, 30 seconds to read the index, 10 seconds to open the page, and then adds...not much help. The main problem is the crew taking a finite time to recognize what the issue is, and then to work out what is good, and what can work next to sort out their issue. The Jet upset, flight with unreliable airspeed, etc is all well and good, and great guidance, when the crew are aware that it now applies to their suddenly unhappy world. the upset training we do in the sim is vanilla flavored; 'OK, blogs, and bloggette, today, we are going to do UA. hand over the aircraft to the other pilot, and put your head down.... now....... wait for it.... wait for it..... OK.... recover.... " Just like the real world. So in the sim, having been prebriefed of the event, and recovery, and then at the point of the session that it is undertaken, then being a party to the process of the setup, and preparing for when they open up their eyes, we end up missing the bit that happens in the real world, the time it takes to recognize that the world just ain't so, and that all that training in the sim needs to be applied in an eye-pleasing manner. In summary, all the training in the world on upset technique will matter nowt, if the crew don't recognize that they have a problem in time to apply their techniques so assiduously gained in the sim sessions. Funny thing is, its not that hard to set up, we just don't have the inclination or enthusiasm to do it. There is a downside to such SA training, as that is what it is, and the lack of SA training is what keeps killing people. The problem is (and was noted in an SA training workshop some 27 years ago), that a competent crew member losing SA in a training session has a huge hit to their ego, and confidence needs to be restored thereafter. Canned UA training is a step above lipstick on the pig, and alone will not improve the outcome. The training and recurrent training programs we have are a bureaucratic box-ticking exercise, not risk reduction oriented, and that is a missed opportunity. AQP was supposed to improve that and ended up being hijacked by beancounters and compliance managers.

If SA becomes recognized as the fundamental issue we have in aviation, then that epiphany gives a direction towards solutions that may be meaningful. Or we can apply more regulatory bandaids, as the FAA did post Colgan. WTF!
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Old 11th Feb 2021, 03:25
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Disagree. Less automation. A “better” system will fail in a new and improved way.
No! definitely better automation. Airbus already has it. The computers restrict asymmetric effect and also the AP trimms rudder as well. Moreover thrust when it fails fails at present value. It's basic demonstration for EFATO. Whether throttles move is not the issue. Even with static thrust levers Engine failure at cruise has same effect. No ATHR means long winter holiday, no CAT3.

Last edited by vilas; 11th Feb 2021 at 03:56.
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Old 11th Feb 2021, 07:09
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Originally Posted by fdr View Post
Hmmm, conflicted on the need for the CVR to shed light.
The recommendations will almost certainly add a need for better training, but of what? Of being human
Bingo! The real problem here is the assumption that airplane makers make about humans: that they can be programmed like machines.

Nothing could be further from the truth. For starters, we now know that human consciousness does not perceive reality directly, but actually as an indirect hallucination based on sensory inputs. Homo sapiens do not experience reality as is, there is a layer in between. To make it worse, we believe that our perception of reality is reality.

No amount of training can change that. No amount of blaming the pilots can change that. And yes, it can happen to you. You don't know when it hits you. Your perception departs from the true reality, and when the two don't match, you are caught in cognitive dissonance which consumes 110% of your brain power, losing time to recover from salvageable situation.

The only solution to this is to completely redesign the industry around this simple fact (airplane-human interface, SOPs, CRM,...). Now what are the chances of doing that, eh?

So we will continue to blame the pilots, call it "pilot error", where in reality it's just bad design. Until the AI takes over....
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Old 11th Feb 2021, 09:29
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fdr derjodel and others above

We have the same discussion after practically every accident and incident that involves loss of control, cfit, etc. The fundamental problem is that humans (some of them) are good at doing one thing, while automation (all of it) is good at something else. Automation, as long as it works, is good at performing precisely and flawlessly mundane repetitive tasks, precisely those where humans are likely to make mistakes because of boredom, complacency, tiredness, distraction. How many times in living memory did it happen that an autopilot failed to level off in ALT mode at precisely the preset altitude? Exacly none... How many times did it happen that those twitchy fingers turned that knob to the wrong altitude... ? On the other hand automation is incapable of performing anything outside the limits of what it was designed to do, including recognising its own failure. Humans on the other hand are quite capable of thinking creatively and out of the box, and can process and act upon a vast amount of visual information very rapidly, especially in situations they have been preconditioned to.

The fundamental problem is that humans are not equal (despite all the wishful thinking by some). Some have better skills than others in different areas. It is true that piloting an aircraft 50-60 years ago required above average skills in many areas. However the regular appearance of smoking holes around the world showed that even these above average individuals were prone to making mistakes, and sometimes simply the situation turned so complex that the human brain could not catch up with it within the time frame available. With the onset, development and improved reliability of automation, these situations have been vastly reduced, and piloting an aircraft no longer requires exceptional skills, anyone with a good average skill set can do it safely as millions of takeoffs and landings prove around the world. However the advance of automation brings about one aspect that is very difficult to deal with. It now requires way above average skills to recognise and anticipate the various situations that may arise if one or more components of the surrounding comfortable automation fails, and at least average or better skills to recover from an unanticipated situation. By definition, at least half will fail with the latter, but recognising those who will in advance is very difficult because training by nature conditions for anticipated situations.
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Old 11th Feb 2021, 09:35
  #552 (permalink)  
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derjodel

Autonomous flight over populated areas, or with a large number of pax is a loooooooong way off I wager. The reliability doesn't exist at present to make it possible. The car case has 2-D dynamics with predictable interactions. The aircraft has 3-D dynamics and has interactions with weather, traffic, technical faults that all need to operate perfectly. As this sort of flight indicates, there is a technical issue that triggers the outcome, and the system has to get it right, every time, without external input. Humans remain the most effective safety device for making decisions under conditions of uncertainty at this time. I don't think removing the human from the loop is the solution, I do think that enhancement in SA training is 1/2 a century overdue, and would be cost-effective and "impactful". At least bringing in UA training that are not canned exercises in training sessions would be illuminating and might change the views of some observers to the "only happens to them, not me" brigade.
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Old 11th Feb 2021, 12:31
  #553 (permalink)  
 
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Originally Posted by Check Airman View Post
Uplinker

Disagree. Less automation. A “better” system will fail in a new and improved way.

Why wasn’t the rudder controlled by the pilot?
What is needed is better automatics and better integration with all systems and the pilots. I am type rated on, and have flown both Airbus FBW and B737 on the line, and I have to say the Airbus FBW is excellent but the B737 automatics are more primitive and have to be watched carefully.

If an aircraft like this B737 can go from normal flight on automatics to loss of control unless PF takes immediate action on the rudder pedals and ailerons, then is it a truly stable aircraft? Why doesn't the autopilot control the rudder?

And is it realistic for the B737 PF to keep their hands and feet on the controls at all times, including during the cruise, just in case an engine suddenly fails and the A/P drops out?
.

Last edited by Uplinker; 11th Feb 2021 at 12:44.
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Old 11th Feb 2021, 12:49
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Originally Posted by Uplinker View Post
If an aircraft like this B737 can go from normal flight on automatics to loss of control if an engine suddenly fails, unless PF takes immediate action on the rudder pedals and ailerons, then is it a truly stable aircraft?
Any conventional aircraft will do just the same. Remember the light twin from the multi engine training? Try flying that without rudder and ailerons with an engine out.

Originally Posted by Uplinker View Post
And is it realistic for the B737 PF to keep their hands and feet on the controls at all times, including during the cruise, just in case an engine fails and the A/P drops out?
It is not and it is not even required. At higher speed, the engine failure with regards to controllability isn't a problem, as significant margin to Vmca exists. Asymmetric thrust can be easily recognised by progressively increasing deflection of the control column towards the live engine, and the autopilot will put in quite a lot of force/deflection before it gives up.

I have to say the Airbus FBW is excellent but the B737 automatics are more primitive and have to be watched carefully.
I've got experience of both and both need to be watched like a hawk. The only difference is that with one you can rest your hands gently on the control column and thrust levers and look out the window, and with the other one you need to have your eyes glued to the FMA and N1/EPR to see if something untoward is going on.
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Old 11th Feb 2021, 13:12
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Uplinker, I normally find your posts quite good and balanced, That one though is ridiculous. What are the pilots doing through all of this, may I ask?
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Old 11th Feb 2021, 13:46
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We have a good idea they was comunicating with ATC several times, they was configuring the aircraft for cruise, they was manipulating the AP for heading AND level change, they certainly have been discussing weather as they requested heading change for weather.
In my airmchair pilot experience there was actually quite a bit going on in the cockpit through all of this.
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Old 11th Feb 2021, 14:59
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Uplinker

As an alternative, you could do better selection and training. Not to say that there aren’t flaws, but how much better should the integration be? Do we need a neural link, with the plane plugged into our brains?

I’m not rated on the 737, but I assume that the control column would have been fully deflected as the AP applied aileron to correct. Is that right? We’ll really need the cvr to see what was going on at the time, but I fear Centaurus has already given us a preview.
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Old 11th Feb 2021, 15:27
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Quote: "I’m not rated on the 737, but I assume that the control column would have been fully deflected as the AP applied aileron to correct. Is that right? "

Not really, the 737 AP will disconnect when unable to hold a course or heading selected in the MCP, even in LNAV under certain conditions. The initial roll of 45 degrees should have been managed by the crew..
It seems they are not the only crew bitten in the arse by a 735:
https://www.flightglobal.com/safety/...140072.article
As an observation, It appears the transition from AP to manual flight, coupled with lack of diagnosis and CRM is an "ongoing trend"
When we teach Upset recovery, normally the PF is told to close their eyes and then open when the condition has established, and depending on our degree of nastiness, I've never seen a crew that couldn't eventually recover, some make a mess, but having said that, sitting in the comfort of a sim is a world apart as psychologically you know there is a safety net. The guys that do mess up always say " I would never do that in the REAL aircraft" nonsense, that's exactly what they would do.
I just got two things out of my draw, my "bottom dollar" to bet its a CRM issue and "my hat" to eat if it's not!
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Old 11th Feb 2021, 15:48
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Really ?

QDM360

From Report..
1. Auto Throttle broken. Repaired twice.
2. During take off AT pulls back left engine. AP engaged around 2000 feet.
3. At around 8000 feet, AT again pulls left engine down. Right Engine stays. Continue climb.
4. At 10600 feet, AT again pulls left engine. Right engine stays.
5. Altitude drop. Pitch nose up. Roll started (to left). Then AP disengage. Then nose pitch down.
6. FDR stops recording after 20 seconds. No detail data released.
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Old 11th Feb 2021, 16:07
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Spurious activation of Reverse Thrust

It looks like a spurious signal from the EEC drove the left Thrust Lever to idle to allow for an inadvertent deployment of Reverse Thrust (ala Lauda Air over Thailand). As Auto Thrust was engaged, the right engine will drive forward or remain in position to compensate for the loss of thrust from the left engine. It is this this assymetric condition that brought about the uncommanded bank resulting in the Auto Pilot tripping.
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