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Boeing incidents/accidents due to Thrust/Pitch mode mishandling

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Boeing incidents/accidents due to Thrust/Pitch mode mishandling

Old 10th Oct 2018, 23:25
  #21 (permalink)  
 
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A big problem is that "the automated systems are more competent than the pilot" is largely a true statement. From what I've seen in general, I would place more stock in the automation saving the pilot, than the other way around.
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Old 11th Oct 2018, 00:04
  #22 (permalink)  
 
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Originally Posted by Vessbot
From what I've seen in general, I would place more stock in the automation saving the pilot, than the other way around.
The problem Vessbot is that you haven't seen (do you fly?) all the saves that have been made by pilots but which don't get reported. AF 447 alone, I think I read that that event (or similar) had occurred 30 times previously, but with no dramas as the situation was recovered by the pilots. Bad design, pilot save. When finally pilots don't save it, much gnashing of teeth occurs blaming the drivers, who are themselves victims of Magenta Line policies of the regulators, operators and manufacturers.
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Old 11th Oct 2018, 00:35
  #23 (permalink)  
 
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I am reminded of Murphys original quote, (not the often misquoted "Murphys Law")

One day, after finding that a transducer was wired wrong, he cursed the technician responsible and said, "If there is any way to do it wrong, he'll find it."
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Old 11th Oct 2018, 05:44
  #24 (permalink)  
 
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Originally Posted by parabellum View Post
Todays 'Child of the Magenta Line' has no basic flying experience of any depth to fall back on so when things go wrong and the pilots don't fully understand the capabilities and limitations of automatics and are convinced the automated systems are more competent than the pilot and will always save them, then disaster is only a short step away.
Unfortunately this seems to be true...

Last edited by ScepticalOptomist; 11th Oct 2018 at 05:59.
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Old 11th Oct 2018, 08:09
  #25 (permalink)  
 
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I'm always amazed by the extent that pilots are willing to blame our colleagues for assumed screw ups while secretly hoping we don't make the same mistake. And when it comes to accident investigation, blaming the operator is the easy way to get to a conclusion. In the Asiana accident at SFO, I've heard many times that it was pilot error - even mainstream media in the US made a joke about it.

But modern accident investigation has moved on from simply blaming the operator as it doesn't stop the same or a similar incident from recurring - which is the primary aim of holding the investigation in the first place. In this incident, you have to look at why the crew didn't manually apply thrust on the approach. By saying "they were stupid" stops the investigation right there and then. You think you have found the issue and when the airline trains their pilots better, the problem goes away. That's until it happens again - which it probably will.

But a thorough multi level investigation will look at the Airline's SOPs, their training system, their culture etc. And as the system correctly maintained and working as it should? Were the crew fatigued? Did they get their mandated rest period? Does the airline have fatigue mitigations in place? It will look at the airline's regulator to see how effective it is in ensuring training and safety standards are met. Then it will look at the design of the AT system. Is it fully understood by other operators using substitution tests, have there been similar incidents reported? Are similar incident actually being reported perhaps distorting the true picture? What was the certification process that led to the system being included - was it effective and did it consider all the threats at pitfalls? So much to consider!

I've flown a similar type with the Thrust Hold AT mode which caught the Asiana crew out. I was warned about it during training and that it can seriously bite you on the bum. Despite the warning in training, I've witnessed the speed reducing while a pilot says "What's it doing now?" to be told "Thrust Hold mate!" on many an occasion. I've done it myself! And at the end of a 14 hours sector after some dodgy crew rest, making an approach in tricky conditions at an unfamiliar airport in a new aircraft in your window of circadian low, I can see how all the factors stack up to make an accident like this more likely. Sure, the crew made an error. But just by pointing the finger at the user will not address all the factors.

And if you ask me my opinion about this accident, I would have to ask why the manufacturer thought it was sensible to have an AT mode which tells you the AT is working, but doesn't let you know the thrust levers won't move.

Last edited by Dan Winterland; 11th Oct 2018 at 08:53.
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Old 11th Oct 2018, 08:38
  #26 (permalink)  
 
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Well said, Dan.
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Old 11th Oct 2018, 14:36
  #27 (permalink)  
 
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And if you ask me my opinion about this accident, I would have to ask why the manufacturer thought it was sensible to have an AT mode which tells you the AT is working, but doesn't let you know the thrust levers won't move.
This. And “this is the way we did it in the sixties” is not a valid excuse.

The children of the magenta line line trope is getting tired. I’m more concerned about someone who is reluctant to embrace change (look at the incomprehensible Boeing FMAs) and who thinks that everything in aviation is lightning fast reactions and seat of the pants skills.
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Old 11th Oct 2018, 15:16
  #28 (permalink)  
 
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Originally Posted by Capn Bloggs View Post
You old codgers can rant and rave all you like. The concept that a perfectly serviceable autothrottle system would just stay asleep when the speed was 30 knots below Vref is ludicrous.
Is it? Really? The autothrottle system was dependent on the rad alt, so when the radalt failed, the autothrottle failed. The flight crew is not dependent on the radalt. Changing the above statement slightly results in the following truism: The concept that a flight crew would just stay asleep when the speed was 30 knots below Vref is ludicrous.
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Old 11th Oct 2018, 15:38
  #29 (permalink)  
 
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Originally Posted by KenV View Post
Is it? Really? The autothrottle system was dependent on the rad alt, so when the radalt failed, the autothrottle failed. The flight crew is not dependent on the radalt. Changing the above statement slightly results in the following truism: The concept that a flight crew would just stay asleep when the speed was 30 knots below Vref is ludicrous.
I would also suggest that during the design and certification of the system, the safety analysis assumed a trained and competent aircrew, too. With hardly any change in such assumptions from the 60's and 70's.

In my opinion, the last three decades of design and operational use of automated systems in the flight deck has gradually led to less vigilant instrument pilots. Everything works so well, almost all of the time, and when it doesn't it may not be obvious, except to a vigilant grew watching the instruments instead of the system.

I don't blame the pilots, they are the victims of this systematic paradigm shift. Considering how important airspeed control is during the final approach, who would have guessed that pilots would be so inattentive (for two minutes, and this isn't the only such accident)? Unless you have been in the situation after hundreds (thousands) of approaches when "other things" held their attention, and nothing went wrong.

Think how much "better" things will become when airlines achieve their goal of single pilot airline crews, and/or "warm body" co-pilots.
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Old 11th Oct 2018, 21:09
  #30 (permalink)  
 
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Fly the plane, that’s what you are there for.

The automation is an aid.

Those of you that can’t grasp the concept that the pilot is solely responsible for the flight path, and not the autopilot, need to grow up and finally take responsibility for what you are doing.

Stop blaming the system for incompetence.

Its a scary aviation world we are getting in to, where the new generation of pilots are looking to blame the system for unintended and undesirable flight paths, rather than take responsibility for being the Pilot in Command!

The Boeing automation is simple and easy to understand. All you have to do is read the books....

Boeing also assume competent and trained pilots are flying their aircraft.

What an outrageous assumption to make!!! Who would think that competent and trained pilots would be in command of jet transport airplanes! Oh the horror of requiring such a thing!!

grow up.
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Old 11th Oct 2018, 21:58
  #31 (permalink)  
 
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If a technical systems fails / malfunctions in circumstances leading to a hazardous situation, and where comparable systems / aircraft provide sufficient mitigation against this hazard, then irrespective of human performance, assumed or otherwise, then the deficient technical system should be corrected.

The debate in the above is with what is assumed to be hazardous.
The technical outcome of an accident is objective fact; but the assessment of human performance either with hindsight or expectation in future situations is always subjective, uncertain.

‘Precautionary Principle’ … defines actions on issues considered to be uncertain, for instance applied in assessing risk …
"… caution practised in the context of uncertainty"

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Old 11th Oct 2018, 22:25
  #32 (permalink)  
 
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I would also suggest that during the design and certification of the system, the safety analysis assumed a trained and competent aircrew, too. With hardly any change in such assumptions from the 60's and 70's.
With the exception of the 787, the autothrottle cert basis on all Boeing aircraft was for a 'Design Assurance Level' (DAL) B or C system (depending on which aircraft) - 'flight critical' is DAL A. In other words, a DAL B/C system doesn't have to be perfect, because it's assumed a competent flight crew will notice if the A/T isn't doing what it should and intervene... It was something of a hassle for those of us on the Propulsion side, since we had to assume the A/T could do something stupid so we needed to design our systems to account for that. I don't know if that little tidbit - that the A/T is not designed or certified as a flight critical system on most Boeing aircraft - is included in the flight crew training, but if it's not, it should be...
My understanding is they finally upgraded the DAL of the autothrottle to 'A' on the 787 (although I don't know that for a fact).

And at the end of a 14 hours sector after some dodgy crew rest, making an approach in tricky conditions at an unfamiliar airport in a new aircraft in your window of circadian low, I can see how all the factors stack up to make an accident like this more likely.
I don't dispute that fatigue likely played a factor in Asiana, but what part of landing at SFO on a beautiful, clear, sunny summer day would constitute 'tricky conditions'? If a pilot can't handle a near perfect summer day without hitting the sea wall, what chance would they have at night in a storm?
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Old 11th Oct 2018, 22:50
  #33 (permalink)  
 
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Originally Posted by Capn Bloggs View Post
The problem Vessbot is that you haven't seen (do you fly?) all the saves that have been made by pilots but which don't get reported. AF 447 alone, I think I read that that event (or similar) had occurred 30 times previously, but with no dramas as the situation was recovered by the pilots. Bad design, pilot save. When finally pilots don't save it, much gnashing of teeth occurs blaming the drivers, who are themselves victims of Magenta Line policies of the regulators, operators and manufacturers.
This little tidbit is encouraging, but the attitude I see day in day out at the airline I fly for, is not: that handflying is an entertaining frivolity, only to be reserved for the clearest calmest of days (if even then). Competency in it is assumed, on no basis. Numerous times I've heard from check pilots and instructors "we know you know how to fly the airplane at this stage, so the focus is on [everything else]" when they actually don't know that at all. Seems like it comes out like a verbal tic. All the big talk about our substantial responsibilities is about managing the big picture and being an automation manager... as if that's something to do not in addition to knowing how how to fly, but instead of it. In all of newhire sim training, to my best memory, I did two handflown approaches. The rest was all profiles and procedures. I get thrown out onto the line since all the required boxes are checked, and then I could fly until upgrade, literally without intercepting a course or levelling off from a decent even once. And, if I followed the example from the left seat, this wouldn't be too far from the truth.

When we're getting vectored to expect a tight visual because of a storm on long final, and he's nervously fidgeting with the heading knob a few degrees back and forth while telling me not to call it in sight yet, instead of just flying it in, it's clearly revealed to me which way the automation/pilot/saving relationship is arranged.
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Old 11th Oct 2018, 23:05
  #34 (permalink)  

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tdracer, that's probably not worded to describe precisely the SFO accident. Anyhow the energy level was tricky. Intercepting a standard 3 deg profile from above, with a rather low-and-close geometrical intersection point is a beast. Your mind is firmly set that you are hot and high, so you WANT idle thrust....

and then

... In fact, as you intercept the G/S, heaven forbid the AP or pilot pulling up to capture it - oh wait, there is no other way - the A/C if still with idle thrust is in a SEVERE low energy state. Add to that a bit more pull to recover the duck-under (no matter A/P or human) and you have a 7n7 with a 6-8 degree DOWN trajectory vector, full landing flap with L/G down and 5 deg NU pitch to recover the profile and it is an extremely high drag configuration. The inertia is massive.

If not anticipated it all happens very fast and the recovery N1 is in the low 80s. Feel free to ask how I know.

Another trap is how un-common it is. These days especially long-haul it is ILS to ILS and stable-coupled from 15 NM. And guys get about 2 landings a month each. The chances of recognizing not only that the situation is wrong, but how quickly and deeply bad it is about to become are practically nil. And then you are left with the reactions. Why theirs came late is elementary HF.

In this respect both AMS 737 and SFO 777 wouldn't have happened if it was not for the intercept from above to begin with, I am quite convinced.
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Old 12th Oct 2018, 00:43
  #35 (permalink)  
 
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Originally Posted by Ken V
Is it? Really? The autothrottle system was dependent on the rad alt, so when the radalt failed, the autothrottle failed. The flight crew is not dependent on the radalt. Changing the above statement slightly results in the following truism: The concept that a flight crew would just stay asleep when the speed was 30 knots below Vref is ludicrous.
Ken, I was referring to the SFO 777 prang, not the 737 at AMS. The 777 was fully serviceable, but by design, the ATS didn't wake up even though the speed got to Vref-30. If what Tdracer has added is true, it seems Boeing has had a change of heart with the 787.

Originally Posted by Switchbait
Fly the plane, that’s what you are there for.

The automation is an aid.

Those of you that can’t grasp the concept that the pilot is solely responsible for the flight path, and not the autopilot, need to grow up and finally take responsibility for what you are doing.

Stop blaming the system for incompetence.

Its a scary aviation world we are getting in to, where the new generation of pilots are looking to blame the system for unintended and undesirable flight paths, rather than take responsibility for being the Pilot in Command!

The Boeing automation is simple and easy to understand. All you have to do is read the books....

Boeing also assume competent and trained pilots are flying their aircraft.

What an outrageous assumption to make!!! Who would think that competent and trained pilots would be in command of jet transport airplanes! Oh the horror of requiring such a thing!!

grow up.
A well-rounded, balanced view of the current state of the industry...
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Old 12th Oct 2018, 02:04
  #36 (permalink)  
 
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Switchbait.
Fly the plane, that’s what you are there for.

The automation is an aid.

Those of you that can’t grasp the concept that the pilot is solely responsible for the flight path, and not the autopilot, need to grow up and finally take responsibility for what you are doing.
Stop blaming the system for incompetence.
Its a scary aviation world we are getting in to, where the new generation of pilots are looking to blame the system for unintended and undesirable flight paths, rather than take responsibility for being the Pilot in Command!
The Boeing automation is simple and easy to understand. All you have to do is read the books....
Boeing also assume competent and trained pilots are flying their aircraft.
What an outrageous assumption to make!!! Who would think that competent and trained pilots would be in command of jet transport airplanes! Oh the horror of requiring such a thing!!
grow up.

Bloggs
A well-rounded, balanced view of the current state of the industry...
Well stated. If the pilot does not understand the if/thens and the cascade of sequences involved in the system processes, it is the systems fault?

There is absolutely nothing in placing blame where blame belongs.

The system is there to HELP you fly the ac.

The pilots job is not to be there to take over when the automation makes a mistake. ummm, never mind, that was not the original intention of the automation.
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Old 12th Oct 2018, 03:27
  #37 (permalink)  
 
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Originally Posted by Underfire
Well stated.
I was being sarcastic. That diatribe from Switchbait is one of the bigger loads of nonsense I have read.
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Old 12th Oct 2018, 10:02
  #38 (permalink)  
 
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If what Tdracer has added is true, it seems Boeing has had a change of heart with the 787.
Sadly not, it’ll do exactly the same thing.

To the the poster who says that the Boeing FMAs are easy to understand if you read the manuals: I put to you VNAV climb or descent, where there is no indication whatsoever on the FMAs (or PFD for that matter) that the aircraft will or will not level off at some intermediate altitude. It can’t even handle the job of making a constraint that’s referenced to STD while QNH is set, or vice-versa.

Or the fact that approach mode only works for IAN and not an RNAV approach with multiple constraints; or the fact that you can’t arm APP until established on the localiser / FAC; or that you have to do a silly pressurisation sequence of the hydraulics / fuel pumps before engine start even though they’re all load shed anyway; or that it has no comprehension of passenger comfort in VNAV descent; or that it will exceed its thrust capability in HDG SEL at high altitudes; or that you have to use a mouse pointer to click on dinky virtual FMC buttons; or that doing direct to a waypoint doesn’t automatically engage a navigation mode; or the hold entries that would fail an IR; or the most annoying trait of all of making you tweak the HDG bug every minute or two for FOURTEEN HOURS STRAIGHT because they couldn’t figure out how to slave it to the actual heading.

Feel slightly better for getting that off my chest.
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Old 12th Oct 2018, 11:39
  #39 (permalink)  
 
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A now retired simulator instructor at Boeing told me they designed the 787 on the assumption it would be flown by incompetent pilots; hence all the protections.
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Old 12th Oct 2018, 13:35
  #40 (permalink)  
 
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Originally Posted by Centaurus View Post
A now retired simulator instructor at Boeing told me they designed the 787 on the assumption it would be flown by incompetent pilots; hence all the protections.
Not doubting he said that. But, he was pulling that assumption out of his ass.
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