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Nepal Plane Crash

Old 16th Feb 2023, 20:01
  #521 (permalink)  
 
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Little war story: On one of my first fights in a small aircraft (just before I began my own training), at the completion of the 150nm cross-country we ended up a bit high on final.

The newly-minted (and thus very current in training) pilot in the left seat reached over to pull back the C152's throttle and reduce power. Which he did very successfully - the engine and prop stopped altogether. He had grabbed and pulled the MIXTURE knob all the way back. Despite it being 1) screaming RED in color, and 2) having a push-button lock to prevent inadvertent movement.

At which point the excess altitude became very useful - as we glided to a perfect touchdown on the runway.

Pilots at all levels of experience can do (and have done) the darndest things. Which is why, whenever I see an argument that "No pilot would ever......," I carefully fold it four ways and deposit it in the trash-basket.

Had we crashed, the investigators would no doubt have found the mixture lever at cutoff, just as the investigators here found the condition levers at feather.

There may be two condition levers - but they are intentionally set very close together (cheek by jowl), because they are usually moved as one to maintain symmetrical engine conditions.
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Old 16th Feb 2023, 22:22
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Just a thought of another hole in the cheese, with two Captains flying together, how much flying had the PM done recently from the RHS? Operating levers and flows on different from your “normal” side can throw all sorts of little hesitations and errors.
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Old 16th Feb 2023, 23:34
  #523 (permalink)  
 
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Originally Posted by pattern_is_full
Had we crashed, the investigators would no doubt have found the mixture lever at cutoff, just as the investigators here found the condition levers at feather.
Has there been a report that the condition levers survived the fire and were found in the feather position? If that was in the preliminary report I must have missed it.
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Old 17th Feb 2023, 01:20
  #524 (permalink)  
 
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My poor phrasing (still partly in C152 mode ) - substitute "deduced from the FDR data of the Np and Torque that the propellers had been feathered."

I'd imagine that the instant they saw that data, they went back to the pile of wreckage to see if the levers could be found.
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Old 17th Feb 2023, 04:26
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Props Feathered , What prevented them from gliding further out ? Stick Shaker Activated , Flaps 30 ?

What would happen if the Condition Feather was suddenly put to AUTO with engine in Full Throttle as it was in the last moments , any Unsymmetric thrusts that could have created a rollover?
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Old 17th Feb 2023, 04:49
  #526 (permalink)  
 
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Originally Posted by ATC Watcher
Indeed and it is why Ihave a bit difficulties in accepting a simple lever mix up. In addition to what you said, the flaps is one lever, conditions are 2 , and as someone explained earlier there should be specific buttons to push of pull to go to feather. These facts combined with quite experienced pillots , which had done 3 evious flights on the same aircraft that day , almost CAVOK., no real stress or emergency , just a request for a QFU change , it does not really add up.. .I think we are missing something here.
Unlikely stuff can happen. Flew on a conventional type with a yoke mounted checklist with a little plastic marker that marked where one was in the lists. At the end of the landing checklist the marker was usually moved completely up in preparation for the next flight. One day the PM, instead of moving the marker up, grabbed the flap handle and moved it fully up, through 2 gates. Slow moving flaps and a quick reaction by the PF saved the day. Sector 4 at the end of a day. In that case a go-around was successful, a report was written, some additional training happened and everyone was happy. But not only was it a completely different location, but also shape of control, just the direction of movement was similar.

For similar reasons some operator require pilots, before acting on flaps or gear calls, to grab the control, repeat which they want to move, wait a second or two to allow intervention by the PF in case it is the wrong item, and only then move it. That slows things down, but prevents transferring one muscle memory movement to the wrong control.
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Old 17th Feb 2023, 07:04
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I have found that the link doesn't work, also the same one (I think) in LinkedIn posts, however here is a link that does work: https://www.flightradar24.com/blog/w...ary-Report.pdf
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Old 17th Feb 2023, 08:55
  #528 (permalink)  
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@ Denti. very interesting story, we are now getting into complex human factors,. I have seen such incidents with single pilots in high stress situations , which we call :" buried memory ", where your brain is overloaded and automaticallydoes things based on actions buried in your memories, as your brain can only function in sequences , not at the same time (despite many women believe they can ).

While the example descrbed by pattern_is_full on an old Cessna is easily understandable, as the 2 levers, throttle and mixure are not only side by side but have the same push-rotate knob, and behave the same, just the color is different. Not the first time this error occurred and will not be not the last time .
But the feeling of taking 2 round shaped levers, (de) pressing 2 knobs to get into feather instead of delatching a single flap lever with its distinctive wing shape, is totally different and frankly I never heard of this before , on any type. And not picked up by the PF either? But there is always a first on everything I agree.

One point that migh be worth looking at here is fatigue and sleep deprivation as a posible contributing factor. We know they've done 3 previous legs that morning , but what they did the night before ( not necessarly work related) can be a factor Colgan and AF447 come to mind..
But the mystery continues until we get the final report in a year or two I guess.
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Old 17th Feb 2023, 09:46
  #529 (permalink)  
 
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For low-currency pilots in a hobby environment there have been cases where quite dissimilar controls have been confused.
Cognitive decline has also been suspected in these cases, especially when older pilots were involved.

Since I cannot post links yet:
bea.aero/en/investigation-reports/notified-events/detail/accident-to-the-rolladen-schneider-ls4-registered-f-clmf-on-25-06-2021-at-vinon-sur-verdon/
bea.aero/fileadmin/user_upload/F-CLMF_En.pdf
This is a case where an airbrake handle and a gear lever were mixed up, even though they are very different in this type of glider:
- Linear action backwards vs. pivot lever action forwards
- Different shape of handle
- Different actuation force and force progression
- Blue plastic vs black metal
- High on cockpit sill vs low near armrest

I would not have expected much better trained, supervised and medically checked ATPL pilots in a two-person cockpit to have such a mix-up and not recognize/correct it.
But given the facts so far it has to be viewed as possible, even likely.
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Old 17th Feb 2023, 09:50
  #530 (permalink)  
 
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I would like to know who initiated the change of handling pilot at the last minute. I don't think that is clear from the report.
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Old 17th Feb 2023, 10:26
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Originally Posted by ATC Watcher
Indeed and it is why Ihave a bit difficulties in accepting a simple lever mix up. In addition to what you said, the flaps is one lever, conditions are 2 , and as someone explained earlier there should be specific buttons to push of pull to go to feather. These facts combined with quite experienced pillots , which had done 3 evious flights on the same aircraft that day , almost CAVOK., no real stress or emergency , just a request for a QFU change , it does not really add up.. .I think we are missing something here.
You would be amazed at some of the things that happen on the flight deck. I had a high time captain, who had many years of experience on the large aircraft in question, select the gear down on me when I asked for the initial flap selection.
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Old 17th Feb 2023, 15:38
  #532 (permalink)  
 
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Or worse, a crew member selected flaps up when asked for gear up. Sometimes your brain isn't engaged. How about putting the mobile phone in the fridge? Also happened to sane people.
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Old 18th Feb 2023, 06:42
  #533 (permalink)  
 
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Crikey!

that report is simply shocking. But the signs were there right from the off.

I called the lack of prop / engine noise immediately as well as the feather scenario. But what i never expected in a million years was that it wasn’t due to a mechanical fault, but human error.

blimey its worrying.


777 pilots not checking ALT gauges before enabling AP on T/O and now ATR pilots grabbing completely the wrong levers.

The excuse of muscle memory doesn’t - nor should it - wash. Especially with levers with a totally different ergonomic feel. If they were all the same - i could somewhat understand it - but they are not, for this reason.

the fact that the error occurred and PM didn’t think “Well I didn’t get flaps 30 so what did i do” and subsequently does adjust to Flaps 30 later, still not noticing the error - is scary.

it literally feels like a lottery with the quality of the crews you get these days - almost at the point where I’m tempted to ask the flight crew some Aircraft type trivia questions before boarding.

that isn’t meant to offend those of you that are fully competent (I know despite encouraged automation, SOPS and company CRM some of you do still exist)

airframe reliability has come a long way in the last 20 years. However, Air crew reliability has gone south in a big way.

What a turnaround of events, from highly experienced and well trained crews who sadly found the hardware letting them down in times of old.

A crude estimation, but of the last 10 major Airliner accidents I can think of, at least 80% of them have been flyable aircraft.


Last edited by RiSq; 18th Feb 2023 at 06:56.
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Old 18th Feb 2023, 06:49
  #534 (permalink)  
 
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It boils down to reinvent CRM and good old X-check procedures it seems.
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Old 18th Feb 2023, 08:25
  #535 (permalink)  
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Originally Posted by RiSq
the fact that the error occurred and PM didn’t think “Well I didn’t get flaps 30 so what did i do” and subsequently does adjust to Flaps 30 later, still not noticing the error - is scary.
I have hard time gasping the PF not noticing prop's levers position (Assuming that's what happened)

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Old 18th Feb 2023, 09:09
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Originally Posted by ehwatezedoing
I have hard time gasping the PF not noticing prop's levers position (Assuming that's what happened)
The PF was flying a left-hand visual circuit in the turn from base onto final, so it is not unreasonable for the PF to be looking outside to the left, while the "prop's levers" were inside to the right. Also, there would have been no reasonable 'need' to question the position of the propeller condition levers at that stage in normal circumstances. Good 'check/confirm' SOPs could have brought that attention 'back inside' and notice that the flaps had not been selected but that 'something else had been'.

There have been many, many cases of the wrong controls being moved. I know (second hand) of a few, including: hand moving to the flap lever when "gear up" called after take-off (but stopped short by an observant PF); fuel lever moved to shut-off when landing flap called for (which resulted in a single engined landing, without that final flap selection!). In both those situations the PM was the captain.

Add to that the situation of the trainer ('instructor') being in the different seat from 'normal' where everything is 'the other side'. Add to that fatigue. That was the fourth sector that day, how many had already been flown in the preceding few days and at what sort of start times or length of day? Don't be too critical of mistakes that people may make in situations like that unless you fully understand the circumstances that they were in. Or the circumstances that their work requirements had put them in. I have only known one airline that restricted the total amount of a trainer's workload that can be training. The extra workload on its own is fatiguing and being worked up to 'normal' fatigue expectations pushes this too far. There may be other airlines that also recognise that -- I hope so.


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Old 18th Feb 2023, 09:35
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I cant understand why when the props were feathered that neither PF or PM noticed the difference in engine noise or feel or vibration of the aircraft or change in pitch angle etc.

And when the PF said repeatedly the engines are not producing power, didnt the PM do a visual scan of the controls and see that the props were feathered.
The clue is in the name, Pilot Monitoring. !!!!

Another example of a perfectly servicable aircaft being crashed into the ground by multi thousand hour (28000+) incompetent pilots.

Last edited by michaelbinary; 18th Feb 2023 at 10:04.
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Old 18th Feb 2023, 15:27
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Or --
Another example of a perfectly servicable aircaft being crashed into the ground by multi thousand hour (28000+) incompetent exhausted/fatigued pilots.
-- ??

Details of all their preceding duties would be very interesting.
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Old 18th Feb 2023, 16:51
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25-hour FDR + a FR24 flightpath of a circling app by a different Yeti tail #

Non-pilot here.
Noted in the report in section 1.8.4 about flight recorders is that the investigators were able to go back to a previous flight (on January 12) by the accident AC, with a different crew, that also took a circling approach from the north into RW12. That was 4 days and 23 sectors previously! A cumulative flight time according to FR24 of 695 minutes, averaging 30 minutes per sector.
That's 11 & 1/2 hours of data. Totally possible since the installed FDR had a 25-hour recording time. In an aircraft built in 2007.
Compare that to the hand-wringing on here about the recent runway incursions and near-CFIT incident aircraft having their 2-hour FDRs overwritten by the time the respective flights arrived at destination.

On a similar note I trawled through all the Yeti KTM to PKR flights since the new airport opened on January 1. The accident AC successfully flew this sector 22 times, obviously with different crews, and only twice before made a circling approach to RW12 from the north. The rest were all straight in to RW30. According to FR24 those 2 tracks each had a weird significant RH zigzag about 2/3 the way along the flightpath, possibly a result of missing data points.
Of all the numerous Yeti Airlines KTM to PKR flights I found one circling approach to RW12 from the north that had all of it's flightpath in green (meaning minimal missing data?) - flown by ATR-72 tail number 9N-ALN performing YT671 on January 4. The following screencaps show the final stage of that flight, which has not been shown in this thread previously. The second image is zoomed to show a little more detail.


Source flightradar24


Source flightradar24

Last edited by SLFstu; 18th Feb 2023 at 17:37. Reason: removed Aussie date format to aid clarity
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Old 18th Feb 2023, 18:46
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As a non-pilot I can't understand why the controls shown at post 510 are so similar. Surely the feathering levers should be located somewhere physically away from the flap lever. I do see that there are 'buttons' on one - if they work - but otherwise there are more similarities than differences.
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