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-   -   Boeing incidents/accidents due to Thrust/Pitch mode mishandling (https://www.pprune.org/tech-log/614177-boeing-incidents-accidents-due-thrust-pitch-mode-mishandling.html)

Smooth Airperator 9th Oct 2018 15:26

Boeing incidents/accidents due to Thrust/Pitch mode mishandling
 
Hi all,

Can anyone help me with Boeing (regardless of type) incidents that have been caused because the crew did not understand or use Thrust and Pitch modes correctly or if Thrust and Pitch mode was a related cause. From the top of my head:

-Asiana 777 SFO
-Turkish 737 AMS
-FlyDubai 737 RVI
-EK 777 Dubai

Thanks

Intruder 9th Oct 2018 23:37

The mishap report for Asiana at SFO is available. The Captain grossly mismanaged the autopilot modes, making several changes in rapid succession on final approach. Even after the 3rd pilot in the observer seat warned him twice, he did not correct. IMO, that was COMPLETELY pilot error.

A37575 10th Oct 2018 03:45

The easy way is to Google your request or Google each of the accidents you stated. There have been countless incidents/accidents of this sort. In almost every case the direct cause of the accident/ incident boiled down to the fact that the pilot was automation addicted and lacked basic instrument flying ability. Some may say that is a long bow to draw. Others may have the opinion that the pilot simply didn't know how to fly - a well established result of automation dependency..

KRviator 10th Oct 2018 05:10


Originally Posted by Smooth Airperator (Post 10269632)
Hi all,

Can anyone help me with Boeing (regardless of type) incidents that have been caused because the crew did not understand or use Thrust and Pitch modes correctly or if Thrust and Pitch mode was a related cause. From the top of my head:

-Asiana 777 SFO
-Turkish 737 AMS
-FlyDubai 737 RVI
-EK 777 Dubai

Thanks

I wouldn't entirely classify the Amsterdam 737 accident as the crews fault. The primary cause was a faulty radar altimeter that provided an erroneous signal to the autothrottle that retarded the thrust levers. The crew manually advanced the thrust levers, but because he didn't disengage the autothrottle, the computer again retarded the thrust levers.

You could also include China Airlines 006 in that, after an engine rollback, they failed to monitor their airspeed, resulting an a departure from controlled flight. Again, an underlying issue occurred, mode confusion was not the primary reason.

stilton 10th Oct 2018 05:16


Originally Posted by KRviator (Post 10270060)
I wouldn't entirely classify the Amsterdam 737 accident as the crews fault. The primary cause was a faulty radar altimeter that provided an erroneous signal to the autothrottle that retarded the thrust levers. The crew manually advanced the thrust levers, but because he didn't disengage the autothrottle, the computer again retarded the thrust levers.

You could also include China Airlines 006 in that, after an engine rollback, they failed to monitor their airspeed, resulting an a departure from controlled flight. Again, an underlying issue occurred, mode confusion was not the primary reason.



Pretty incredible youíd blame the AMS
crash on anything other than pilot error


If youíre so clueless you donít recognize
airspeed decreasing without an appropriate
response from The autothrottles, then take over and correct you are incompetent, a passenger not a pilot


Funny, we flew aircraft for decades without
AT, how did we survive?

hans brinker 10th Oct 2018 05:33


Originally Posted by KRviator (Post 10270060)
I wouldn't entirely classify the Amsterdam 737 accident as the crews fault. The primary cause was a faulty radar altimeter that provided an erroneous signal to the autothrottle that retarded the thrust levers. The crew manually advanced the thrust levers, but because he didn't disengage the autothrottle, the computer again retarded the thrust levers.

You could also include China Airlines 006 in that, after an engine rollback, they failed to monitor their airspeed, resulting an a departure from controlled flight. Again, an underlying issue occurred, mode confusion was not the primary reason.

I disagree. The only reason we still have pilots is for when shit hits the fan, anything else can be automated. The radar altimeter failed and that led to the auto thrust to go to idle. The FO pushed the throttle up, let go, it went back to idle, and for the next 100 seconds all 3 of them sat there while the thrust was at idle, and the speed dropped to 83kts, 40kts below Vref.

Same for the China airlines flight. They just sat there, never used rudder trim, let the speed drop until the autopilot gave up, and barely made it out alive.

If we canít handle stuff like this we donít deserve to get paid to fly.

Dan Winterland 10th Oct 2018 07:41

Accident investigation has tended to move away from finding a 'root' or single cause as being responsible for an accident. Also, the practice of finding fault with the operator is also less prominent. People don't go out to deliberately make mistakes. In the 'pilot error' cases mentioned above, the modern accident investigator will look to why the pilots followed the actions they did. If they are as a result of not fully understanding the system, they will look at training/and or manuals. A good example of this, and another case for your study is the B737 serious incident at Bournemouth in 2007 https://www.gov.uk/aaib-reports/aar-...september-2007

The B737 accident at RVI has not yet had it's report published. Although the pitch/power couple with applying full power at a low speed is probably going to be considered a factor, I would strongly suspect that spatial disorientation will feature more.

172_driver 10th Oct 2018 07:44


KRviator 10th Oct 2018 08:11


Originally Posted by stilton (Post 10270061)
Pretty incredible you’d blame the AMS crash on anything other than pilot error

If you’re so clueless you don’t recognize airspeed decreasing without an appropriate response from The autothrottles, then take over and correct you are incompetent, a passenger not a pilot

Funny, we flew aircraft for decades without AT, how did we survive?


Originally Posted by hans brinker (Post 10270064)
I disagree. The only reason we still have pilots is for when shit hits the fan, anything else can be automated. The radar altimeter failed and that led to the auto thrust to go to idle. The FO pushed the throttle up, let go, it went back to idle, and for the next 100 seconds all 3 of them sat there while the thrust was at idle, and the speed dropped to 83kts, 40kts below Vref.

Same for the China airlines flight. They just sat there, never used rudder trim, let the speed drop until the autopilot gave up, and barely made it out alive.

If we can’t handle stuff like this we don’t deserve to get paid to fly.

Respectfully, I think you've both missed the point. I guess you would both argue that AF447 was solely the result of the crew, rather than the fact they lost the airspeed in the first place...

Yes, the crew screwed up (in both AMS and AF447...), in a massive way. I am not disputing that fact at all, nor trying to absolve them of that claim.

But...

Amsterdam was not, in itself, the fault of mode confusion, or automation dependency. The crew recognised the decaying speed, and that the throttles retarded automatically. They then pushed them up, and believed (and this is where their lack of systems understanding failed them) they would stay there - and through lack of basic airmanship, let the speed decay to a point where the accident was inevitable.

Consider the case of Scandinavian 751. Engine surge on the initial climb, pilot does the right thing and reduces power. But the autothrottle restored power on the engine, resulting in dual engine failure and the ensuing crash. The pilot knew nothing about that 'feature', nor did the airline. Is it still their fault for not noticing the increasing power? The moral of the story is, pilots screwup certainly. But rarely does that, in itself, cause an accident and it is fatally simplistic to simply lay the blame for a prang at the feet of the crew.

A37575 10th Oct 2018 08:43


(and this is where their lack of systems understanding failed them
You could apply that concept to practically every aircraft accident. In another words avoid hurting the pilots feelings by saying it is never his fault. It is the fault of the designer. if a student pilot stuffs his round-out in his Tiger Moth and bends the propeller the fault is whoever wrote the Tiger Moth Pilots manual for omitting the vital fact that pushing forward on the stick in this design of aircraft can cause the nose to dig in.

Once upon a time we took responsibility for our own actions. In other words we stuffed up by over-controlling during on the flare, or left the power on for too long and floated off the end of the runway. Now we see the tendency to get out of trouble by blaming everything else except ourselves. The Amsterdam crash was a massive pilot cock-up from the time the autothrottles closed during final to the final impact. It was nothing to do with lack of systems knowledge.

One theory came from a first officer of that airline and that was ethnic culture played a significant role in that accident. The cockpit gradient with the former military trained captain was so steep that neither of the two officers would have dared to take decisive action to prevent the accident lest they caused loss of face to the captain. The operative word being decisive.

Capn Bloggs 10th Oct 2018 10:22

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.


Originally Posted by A37575
One theory came from a first officer of that airline and that was ethnic culture played a significant role in that accident. The cockpit gradient with the former military trained captain was so steep that neither of the two officers would have dared to take decisive action to prevent the accident lest they caused loss of face to the captain.

Are you denying that culture has had nothing to do with any prangs?

Skyjob 10th Oct 2018 10:37


Originally Posted by KRviator (Post 10270126)
...Yes, the crew screwed up (in both AMS and AF447...), in a massive way. I am not disputing that fact at all, nor trying to absolve them of that claim.

But...

Amsterdam was not, in itself, the fault of mode confusion, or automation dependency..

Please stop defending that a crew was not to blame, this forum and the authoritative versions of all but Turkish reports all deny your point of view.
It was crew error, no more, no less.
If it was not, then:
- blame all the other crew for being able to fly the plane with the same problem in the weeks before (as analytical data has shown on the failed system involved it had flown many sectors with this failure present);
- blame all the other crew for not reporting the defect through the tech log accurately enough so it could get fixed;
- blame the engineers for not testing and repairing a reported system for failures, I'll help you: BITE check to see FAULT history...

Flying with a hidden defect is one thing, covered by MEL/CDL etc...
Flying with an unreported defect is another, blame the prior crews for not reporting it to the airline engineers in the only way legally possible...
Flying with a reported defect which has not had a fix attempted due poor system knowledge of engineers hides a lack of training for those engineers...
Flying with a reported defect repaired by engineers as serviceable shows there is a different reason or repair has not solved problem...

Either way, basic airmanship AVIATE, NAVIGATE, COMMUNICATE applies.
AVIATE - monitor what the aircraft is doing, especially close to ground, hands on the controls, this includes thrust levers!
This simple and effective measure would have avoided this accident and loss of life...
It is the first thing you learn when flying on your first day in the plane, the crew did not do it.

The failed component was not noticed, was not disconnected, was not recognised: crew error!
If you see throttles retarding and you are expecting thrust on engines, surely you would not only stand thrust levers up, you'd keep your hand on to ensure they stay there!

A37575 10th Oct 2018 14:56


Are you denying that culture has had nothing to do with any prangs?
On the contrary. You may have misinterpreted what was written. Ethnic Culture has been demonstrated to have had significant influence on crew actions and lack of effective action to prevent a looming catastrophe.
For example: Training a Chinese cadet during a 737 type rating he was asked by his simulator instructor what action he would take if on a highly unstable approach and it was clear the captain was pressing on regardless of all warnings from the co-pilot and there was every indication that the aircraft would likely over-run after touchdown.

The cadet remained silent refusing to answer the question. The instructor gave him another chance and said would you consider taking over control from the captain and initiating a go-around? The cadet looked at the instructor horrified and said he would NEVER consider taking over control from a captain under the circumstances described.

That, my friend, is culture and the bane of common sense flight safety. Blind obedience to authority will never change in some cultures.

Vessbot 10th Oct 2018 16:02

Both statements can be simultaneously true:

A) The system is poorly designed, which contributed to the accident.
B) The pilots committed an error, which contributed to the accident.

The system caused an undesirable aircraft state, and the pilots didn't catch it due to whatever combination of complacency, distraction, automation dependency, etc. It's not quantum chromodynamics.

alf5071h 10th Oct 2018 16:33

A problem with open-ended questions is that you can find whatever you look for. Viewpoint, analysis, opinion, are all biased by the inherent human condition.

There would be greater safety benefit in considering the range of situations and context which humans have to manage. The assumption in this is that humans are influenced by the situation much more than we wish to admit or are able to identify, and thus we like to jump to easy conclusions - hindsight bias.
In most circumstances it helps to consider the human as an asset opposed to a hazard; people are doing their best in situations as they are perceived - by them, at that time.

I doubt that any of the accidents quoted involved lack of technical understanding alone; accidents involve many interacting factors, often without a dominating feature. It’s equally possible for a highly qualified crew with good technical understanding, but still encounter a situation where an appropriate understanding is not recalled or misapplied - just being human. Thus system design or situations might dominate, overcoming human ability in those circumstances.

It is disappointing that several of these accidents involved weak technical features which had previously been identified, but for various reason deemed acceptable.
777 AT has known mode weakness, 737 Rad Alt was an old, but allowable design, but different variants of aircraft incorporate auto flight alerting or disconnect software, providing additional indications, this was not fitted to the particular aircraft. N.B. Combinations of Training flights, ATC influence, and technical weakness.

Other accidents, more than those listed, involved situations where technology has been used to guard against adverse human activity (beyond reasonable human ability), but following technical failure of these guards there is the expectation that the human will manage the resulting situation - a situation beyond reasonable ability (ß22)

AF 447 involved conditions beyond those assumed in certification, technology was lacking thus it has been changed; not so (AFAIK) for the lack of comparator warning in the CRJ (Sweden). Similarly for TOCW MD80 in MAD, particularly where more recent aircraft types have an alert for TOCW failure / MEL operation.

At some point during investigations and reporting of accidents, collective conclusions are formed e.g. ‘LoC’, yet timeline-wise LoC was consequential, involving human understanding and action after the initiating event - a change in situation.
This view argues that there would not have been an accident without the technical malfunction, yet there other non technical examples involving wider operational and environmental aspects which also influence human behaviour, thus technical issues are not a complete answer.

Additionally if the industry has accidents in rare circumstances which involve greater than the assumed probability of occurrence, then we have to question if the regulations or assumptions should be changed; who determines the cost benefit, who pays.

Perhaps the industry’s very good safety record is approaching a point of ‘So Far As Is Reasonably Practical’; then what.

underfire 10th Oct 2018 22:01


A) The system is poorly designed, which contributed to the accident.
B) The pilots committed an error, which contributed to the accident.
So if the pilot does not understand the if/thens and the cascade of sequences involved in the system processes, it is the systems fault?

semmern 10th Oct 2018 22:05


Originally Posted by hans brinker (Post 10270064)


I disagree. The only reason we still have pilots is for when shit hits the fan, anything else can be automated. The radar altimeter failed and that led to the auto thrust to go to idle. The FO pushed the throttle up, let go, it went back to idle, and for the next 100 seconds all 3 of them sat there while the thrust was at idle, and the speed dropped to 83kts, 40kts below Vref.

Same for the China airlines flight. They just sat there, never used rudder trim, let the speed drop until the autopilot gave up, and barely made it out alive.

If we canít handle stuff like this we donít deserve to get paid to fly.

A great indicator of something being amiss with thrust and/or airspeed in the 737 is the trim wheels rolling on and on and on... great clue to intervene manually :)

simmple 10th Oct 2018 22:28

Sorry to be simplistic but when all the bells and whistles fail, if you are a pilot and I used to be one before I was forced to become an aircraft operator! You only need the old formula pitch and power equals performance.
every aircraft works like a Cessna, piper etc. I despair at the state the industry is in when it comes to piloting skills and I only see a small snapshot.

Vessbot 10th Oct 2018 23:08


Originally Posted by underfire (Post 10270691)
So if the pilot does not understand the if/thens and the cascade of sequences involved in the system processes, it is the systems fault?

To the extent that the lack of understanding is due to overly complicated design with easy to miss logic traps, yes.

It's a mistake to take a moralistic stance that looks to assign fault. The pilot screwed up then what, now we can harumph sanctimoniously and feel better about ourselves? No, in the end, people's skulls get splattered and any factor that increases the likelihood is an area to focus on for improvement. It doesn't mater whose "fault" it is.

parabellum 10th Oct 2018 23:20

There was a time when us 'old codgers' as Capt. Bloggs calls us, had to do upwards of 1500 to 4000 hours before we got anywhere near flying a shiny jet and most of that time would be spent single crew flying light twins, in all weathers, with levels of automation that ranged between nothing and not very much, our natural reaction, when things started to go wrong was to dump the automatics and fly manually, (not always a good idea). We had to be taught to believe in the automatics and bide our time and try and solve problems though the automatics, if the automatics didn't solve the problem itself. 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.


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