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Indonesian aircraft missing off Jakarta

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Indonesian aircraft missing off Jakarta

Old 5th Nov 2018, 04:36
  #601 (permalink)  
 
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Originally Posted by Nomad
Maybe the memory action for some of these system failures should be 'Automatics off. FLY. Do nothing for a while. Think'.
It is. That is exactly the Memory procedure for a UA situation. and set X° pitch and Y° N1 (depends on the aircraft type). Pretty simple really.
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Old 5th Nov 2018, 07:17
  #602 (permalink)  
 
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Everybody forgot to: Aviate, Navigate, Communicate in that flight. So those same somebodies it seems ultimately ended up stalling the plane into the Ocean. Securing the flight by any means was priority number one, first and only. Once safe, they could have troubleshooted the problem then.

Cheers,
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Old 5th Nov 2018, 07:39
  #603 (permalink)  
 
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Originally Posted by VGCM66 View Post
Everybody forgot to: Aviate, Navigate, Communicate in that flight. So those same somebodies it seems ultimately ended up stalling the plane into the Ocean. Securing the flight by any means was priority number one, first and only. Once safe, they could have troubleshooted the problem then.

Cheers,
No, it doesn't seem that they stalled the plane into the ocean at all. Virtually all evidence revealed to date is consistent with a high speed dive into the ocean. Whatever happened, stalling the airplane is one of the less likely scenarios.

Last edited by A Squared; 5th Nov 2018 at 08:18.
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Old 5th Nov 2018, 07:48
  #604 (permalink)  
 
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but hey, we've stalled it Bloggs, get the nose down!!
Unfortunately this is not what generations of airline pilots were trained for. Lots of training books and examination requirements were focusing on recovering stall by applying engine power and prioritizing to maintaining altitude.

Which has a valid element, "get the nose down!!" may easily get you into a very unusual attitude you typically never fly in, outside the envelope of your systems (elevator feel, speed trim...) which may just trigger the next unusual reaction of the aircraft.
You may end up in a steep dive out of control if you push it too hard in an attempt to "get the nose down!!", which may have been exactly what happened in this case.
Before you start any agressive maneuvre out of the usual envelope of a large transport aircraft, you should be very sure you are not following a false warning, which can be the result of UAS, like the overspeed warning the birgenair pilots were facing.

There should be no control inputs with two exclamation marks when flying a large transport...
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Old 5th Nov 2018, 07:55
  #605 (permalink)  
 
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Originally Posted by VGCM66 View Post
Everybody forgot to: Aviate, Navigate, Communicate in that flight. So those same somebodies it seems ultimately ended up stalling the plane into the Ocean. Securing the flight by any means was priority number one, first and only. Once safe, they could have troubleshooted the problem then.

Cheers,
And what is the purpose of this post? We don't even know what happened, and yet you already assert that the flight crew screwed up. Oh, if only we could find enough pilots who never make any mistake, then everything would be perfectly safe.

But even suppose we find that someone did something which we now know contributed to the accident, here's something to keep in mind:

It is never enough to find out who made which mistake. It is more useful to ask why the people at the sharp end did what they did. Almost always we find that what the pilots (or other operators) did, made sense to them at the time. With perfect hindsight, and all the time in the world to analyse, we sometimes find that it was not the best thing they could have done. But it is useful to try to understand their limited view of things and limited time and mental processing capacity available, to figure out what they might have thought, and how they might have reasoned. Don't start with the assumption that because they made a "mistake", that these pilots were particularly bad at their job. Others might make the same, or similar mistakes, faced with the same situation and the same set of incomplete, and perhaps seemingly contradictory, information available.

Only then can we start and try to find ways to prevent it in the future.

As Sidney Dekker put it in "The Field Guide to Understanding 'Human Error' "(paraphrasing): mistakes should not be seen as the cause of the accident, but as a symptom of larger problems.

Cheers,
Bernd
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Old 5th Nov 2018, 07:56
  #606 (permalink)  
 
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Originally Posted by Nomad2 View Post
Trouble is these modern, highly automated and computerised jets are so simple to operate that most of the time a school kid can fly them. But when the computers and automation get glitchy, they suddenly need a pilot, and a good one at that'.
Except that the B737 has no computers. The flight control system and STS system is good old 1961 engineering - whacking great 5mm steel cables to all control surfaces, plus a bit of hydraulic servo. And while it can be a bit heavy if all the hydraulics fail, it basically becomes a large Cessna 172. And there are no ‘computers’ to fail.

Even the STS system can hardly be called a computer, as it only has 200 bytes of iron-ferrel core memory. And the comment that the STS was reverse trimming and not assisting, is a bit of a red herring, as it always does that. Most annoying system ever, because pilots like aircraft to be in trim, not out of trim. And the STS can be overcome with trim input, as pilots do every day when hand flying, or by disconnecting the trim system. (Whatever the STS does, you just oppose it, otherwise the control forces are absurd).

And upon trim system disconnection you are left with that enormous clanking manual stab-trim-wheel, with more thick steel cables, that was originally installed as a steam-valve on the Titanic - but it sure saved money on design costs....

Silver
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Old 5th Nov 2018, 08:03
  #607 (permalink)  
 
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Originally Posted by Birdstrike737 View Post
To those of you admonishing your colleagues for tossing around first-impressions while “bodies are still warm,” THAT’S WHAT WE DO! WE’RE PILOTS! This thread is not a news organization, it’s a crowded pub. It’s OK to put your bets on the table about what happened before the investigation has even begun, much less ended.
Hear, hear! Of course it is OK, especially if one's opinion is based on misunderstanding of the aeronautical fact one has heard in some pilot pub, left to ripen in a vat of runaway imagination. A pinch of desire to get attention by fearmongering also helps. Some contributions to the discussion are qualitywise getting close to the heights attained by Chapman, Palin, Cleese et al in 1970s.

Just in case you are really here for information and not, like dirty old me, for entertainment:

Maybe there were aeroplanes of Vought F7U generation that could be stalled at any speed, but to achieve that one needs sturdy airframe that can reach stall before structural limit, powerful elevator that can generate high alpha at high speed and low stick force gradient so the pilot can pull the Gs, all of which transport aeroplanes are lacking. Forget about high speed (high speed as in "significantly higher than 1G") stalls in airliners.

Children of the Magenta is one of the most abused video in the history of the PPRuNe. It's point is not that today's pilots don't know how to fly, it is that over-reliance on the systems we don't really understand can happen to anyone and that pilots should always be ready to go into downgraded GTFOH mode.

Changing of control feel or efficiency is not an issue in itself on any airliner, happens rather frequently and extremely often ends up in successful landing.

STSon NG is nowhere near FBW Airbus autotrim by its speed & authority and it's only half-useful (methinks I'm overcrediting it here anyway). Quick blip on trim switch will stop it doing whatever it thinks is appropriate for the situation. I have no idea if some of its arcane faults can really introduce pitch trim runaway but then it doesn't mater: if it does, memory (or recall if that is your parlance) items for runaway stabilizer include activating both stab trim cutout switches. If it doesn't help, grab and hold the trim wheel. Haven't done MAX conversion yet but I really doubt the mighty MAX is anything but grafting of some new fancy displays and engines on old, tired, 1960ies basic airframe.

Not everything is automated today (taxiing isn't for sure) and even automation fails regularly so why do we have to wait for quite a lot between the crashes so the resident PPRuNe experten get the excuse to air their "we got it wrong and we have to return to the straight aeronautical path" pet theories, despite the humongous growth of air traffic? Well, it's not just about the modern systems being far more reliable than those of steam gauge era. Pilot of yesterday who knew how to fly, unlike the flying youth of today, is mythical creature. Quite a lot of them lost: control or idea where they are or how much fuel they still have and quite a few time we didn't even bother to figure out what happened or when we did, we would just say it was pilot's error while letting the airline that had failed to provide relevant and meaningful training of the hook. Accident rates of today's Indonesia or Africa would put those of USA in 1950ies to shame. Modern pilots (even the dreaded MPLs) are well trained and cope successfully with instrument/system/automation failures on daily basis (collectively, that is), flying manually just fine. Most of the incidents don't make it even as far as AvHerald and remain buried in company safety bulletins. Those ending in tragedy tend to be outlying ones where pilots do something so contrary to their basic training that currently we have no psychological tool to explain what the heck they were thinking. Now faced with the things we found dangerous and explicable, and fearing them for a few quite good reasons, we come up with pretty interesting and somewhat flawed solutions. The authorities promulgate the truth that aeroplane can be stalled at any attitude, which is not whole truth as the aeroplanes that recently ended in "any attitude stall" did so with quite active help from their crews in achieving and maintaining stall. Some of the concerned PPRuNers are suggesting more technology, such as AoA indicators, as if the pilot unable to keep the proper attitude will somehow magically be snapped out of his detachment from reality by yet another gauge. While I'm hoping that someone, somewhere will come with the plausible explanation of recent LoC accidents, I'm not holding my breath.
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Old 5th Nov 2018, 08:48
  #608 (permalink)  
 
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Originally Posted by silverstrata View Post


Except that the B737 has no computers. The flight control system and STS system is good old 1961 engineering - whacking great 5mm steel cables to all control surfaces, plus a bit of hydraulic servo. And while it can be a bit heavy if all the hydraulics fail, it basically becomes a large Cessna 172. And there are no ‘computers’ to fail.

Even the STS system can hardly be called a computer, as it only has 200 bytes of iron-ferrel core memory. And the comment that the STS was reverse trimming and not assisting, is a bit of a red herring, as it always does that. Most annoying system ever, because pilots like aircraft to be in trim, not out of trim. And the STS can be overcome with trim input, as pilots do every day when hand flying, or by disconnecting the trim system. (Whatever the STS does, you just oppose it, otherwise the control forces are absurd).

And upon trim system disconnection you are left with that enormous clanking manual stab-trim-wheel, with more thick steel cables, that was originally installed as a steam-valve on the Titanic - but it sure saved money on design costs....

Silver



Sigh, first you were claiming that it wasn't a computer because it only had a 286 microprocessor (Which is a bizarre claim to those of us old enough to recall when all the cool kids had 286 processors in their computers) Now you pop back up claiming it's not a computer because it only has a certain amount of memory ... seriously? Do you even hear the things you're saying? Might I suggest that whatever larger point you might be trying to make is obscured by your misguided and factually incorrect semantics? Whatever this device is, it has a digital CPU, it has digital memory, it takes digital input data and performs logical programming steps to generate digital output data. Most of the rest of the world calls that a computer. If it's really important to you for it not to be called a computer, can you suggest a word or combination of words that you would find acceptable? I don't see that anyone has claimed that the 737 is fly-by-wire a la the Airbus, but it is certainly equipped with a device that most of the rest of the world calls a computer, whcih is autonomously making adjustments to large control surfaces whcih affects how and where the airplane flies.

Last edited by A Squared; 5th Nov 2018 at 13:20.
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Old 5th Nov 2018, 09:03
  #609 (permalink)  
 
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Originally Posted by silverstrata View Post
200 bytes of iron-ferrel core memory.
Core memory, really? There are some very good low powered microcontroller platforms around. Some may be comparable in performance to an 80286, They show up on space probes, where resistance to radiation is important. But nobody is using core memory, other that on a few antiques.
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Old 5th Nov 2018, 09:06
  #610 (permalink)  
 
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Originally Posted by IcePack View Post
Good post Capn Bloggs. Trouble is us pilots spent so many years dumbing down our profession that everyone thinks they can do it. This includes the owners & management hence recruit anyone especially those with money. The schools being commercial operations are very loath to fail those candidates without flying ability as they would loose students. Unfortunately not every one has the aptitude to be a pilot, in the true sense of the word even those that think they do. Quote “Fly the d** Arroplane & don’t over stress it. Get your cockpit management in place (CRM) & get the other guy to diagnose. If you want to confirm what he thinks hand him control & cross check his thoughts. It will be taking 80 to 90 % of your cognitive ability to control an “erroneont” aeroplane.
I think you need your medication adjusted old chap . . . I think I know what you mean but some of it really is in the delivery.
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Old 5th Nov 2018, 09:17
  #611 (permalink)  
 
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I know that sometimes the simulator does not entirely accurately reflect the way that the aircraft behaves, however at no stage during the many Airspeed Unreliable events I have flown in the simulator, did the Speed Trim System do anything at all that I can remember, and it most certainly did not behave in such a way that presented any problem.

I cant help but think this constant reference to the STS in this thread is due lack of understanding of the STS.

I dont know what caused the airplane in question to end up in the sea, but I highly doubt that the STS caused it.....

The data recorder has been recovered. Give them a few days and some FACTUAL information will be available.
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Old 5th Nov 2018, 10:14
  #612 (permalink)  
 
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Originally Posted by Switchbait View Post
I know that sometimes the simulator does not entirely accurately reflect the way that the aircraft behaves, however at no stage during the many Airspeed Unreliable events I have flown in the simulator, did the Speed Trim System do anything at all that I can remember, and it most certainly did not behave in such a way that presented any problem.

I cant help but think this constant reference to the STS in this thread is due lack of understanding of the STS.

I dont know what caused the airplane in question to end up in the sea, but I highly doubt that the STS caused it.....

The data recorder has been recovered. Give them a few days and some FACTUAL information will be available.
I'll cheerfully admit that my entire understanding of the 737 STS comes from this thread, or reading I've done as a result of this thread, so there may be some pretty big gaps in my knowledge. That said, the idea this can't be the cause because it doesn't act that way in the simulator bears comment. Simulators only do what they have been programmed to do. that means that they only simulate failures whcih have been anticipated and programmed into the software. It is certainly within the realm of possibility for a system to fail in a manner that hasn't been anticipated by it's designers, and produce unanticipated results that wouldn't have been programmed into a flight simulator.

Last edited by A Squared; 5th Nov 2018 at 10:37.
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Old 5th Nov 2018, 11:46
  #613 (permalink)  
 
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So having airspeed issue doesn't necessarily result in the aircraft falling out of the sky, as proven on the previous flights. What's different this time?
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Old 5th Nov 2018, 12:10
  #614 (permalink)  
 
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FDR Pingers transmit at 37.5 kHz while most pilots can't hear much beyond 16 KHz (maybe 20 if you are young).

In an earlier life I had some experience finding underwater equipment which was "marked" by a pinger. Pinger receivers usually relay the signal at a frequency that the user (pinger receiver operator) can hear, and some receivers are directional allowing an operator to "home" in on the signal by moving in the direction from which the signal appears to be coming. Having said this, this is not a very accurate way of finding a pinger, and even in shallow water ( 30 m) it is difficult to get much closer than 100-150m from a pinger. Hence the need for divers.

They use 37.5 kHz since there is not so much background sea noise at that frequency.

Seabreeze
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Old 5th Nov 2018, 12:19
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If anyone wants to know a little more about ELBs fitted to recorders, do a search for Dukane DK100 or DK120 or Teledyne Benthos ELP-362D. Plenty of info on them and their theory of operation.
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Old 5th Nov 2018, 12:32
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Originally Posted by dmba View Post
So having airspeed issue doesn't necessarily result in the aircraft falling out of the sky, as proven on the previous flights. What's different this time?
The presence of an engineer for certain.
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Old 5th Nov 2018, 12:41
  #617 (permalink)  
 
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Originally Posted by SLFinAZ View Post
So what do you think that the crews intent was once the UAS issue surfaced. Were they focused on returning to the field (level at 5k vs, gradual climb?) or did they intend to continue the flight as per the previous crew. Given the time lapse (roughly 5 minutes) at roughly 5000 feet without declaring an emergency I'd guess that the crew felt reasonably in control
of the situation. If they intended to continue why not maintain a gradual ascent like the previous flight? If in fact they had flight control issues (vs strictly UAS) why not declare an emergency? Is it possible that the engineer was in the jump seat and making trouble shooting recommendations or observations/requests? Would this create a distraction or complication that would lead to a sudden loss of control?

If the crew had never had a 3rd person involved in a sim setting is it a possibility that the unexpected distraction of that additional voice and potential trouble shooting interaction created enough confusion to lead to a sudden upset or undertake a course of action outside of the preflight brief? I'm wondering if the tech might have asked them to reengage the AP at some point for example?
The data from flight radar (with all the normal caveats) suggests that they never had control of the aircraft.... But your point about the added distraction of an engineer is well made.
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Old 5th Nov 2018, 13:03
  #618 (permalink)  
 
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Originally Posted by Switchbait View Post
I know that sometimes the simulator does not entirely accurately reflect the way that the aircraft behaves, however at no stage during the many Airspeed Unreliable events I have flown in the simulator, did the Speed Trim System do anything at all that I can remember, and it most certainly did not behave in such a way that presented any problem.

I cant help but think this constant reference to the STS in this thread is due lack of understanding of the STS.

I dont know what caused the airplane in question to end up in the sea, but I highly doubt that the STS caused it.....

The data recorder has been recovered. Give them a few days and some FACTUAL information will be available.
Thank you, Switchbait. I have tried to suggest the same, but you have done it eloquently.
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Old 5th Nov 2018, 13:08
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Except that the B737 has no computers. The flight control system and STS system is good old 1961 engineering...
The MAX even has some fly by wire (spoilers) on top.
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Old 5th Nov 2018, 13:42
  #620 (permalink)  
 
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Salute!

I would not be too quick to eliminate a simple problem with the STS or feel system that made another "simple" problem worse( if UAS is a "simple" problem), resulting in loss of control. In other words, a simple reversed wire could have reduced or even reversed back pressure. So pull back and the sucker moves faster/further than you are used to. I speak from personal experience with a reversed wire on my aileron-rudder-interconnect. The jet was very benign WRT rudder requirements unless you crammed in a gob of aileron quickly. So shortly after takeoff I did my normal "sharp" roll to course and whoa! Nose slices the opposite way big time. Scary and neutral stick and no more trouble shooting. My GIB also noticed what happened and we agreed to cautiously come bak and write it up. Sure enuf, the connectors were not polarized and a tech had inserted them the wrong way. So new item on personal checklist when doing the control movement check I would ask ground crew if rudder was moving slightly in direction of roll command.

Even the Boeing description claims that the trim/feel system increases static stability, and the tendency to get back to "trimmed" AoA/speed. So imagine that working backwards!?!

Secondly, you don't need to have a high speed stall to wind up in a high speed dive. You can get there with a slow speed stall and then an unrecoverable dive, although availabkle data does not show any real slow speeds on this plane. The 737 rudder hardovers way back then resulted in steep, high speed dives.

The data should be able to show what happened, and the CVR would be as helpful as it was in AF447.

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