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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 26th Apr 2019, 10:00
  #4361 (permalink)  
 
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Originally Posted by oggers View Post
A small proportion but not a small number. Everyone who has ever ejected, bailed, or faced a major malfunction could be asked and most likely have a range of opinions on the human factors of ET302.
With a common theme - it was not easy and I made mistakes and luck played a part in many of them - but any with ejection seats are never in the position of the ET 302 crew and even Wankazoo ( opps wonkazoo is correct - embarrassing mistake thanks for the PM's I will live with it.) had a "bail" option in real life.

A major malfunction is what an engine failure? every Tom Dick and Harry practice that on takeoff and very often!

Last edited by Bend alot; 26th Apr 2019 at 10:42. Reason: Explanation in the ()'s sorry Wonka - will buy you a beer.
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Old 26th Apr 2019, 11:41
  #4362 (permalink)  
 
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Originally Posted by Ian W View Post
Average professional pilots even below average professional pilots should note and correct out of trim flight. This is C-172 stuff and is not complicated.
Way back in training we were in a C172 about to take off. I'd skipped a checklist item - "autopilot off". Instructor came down on me hard for that one He told me the story of a fatal crash at Leicester UK where pilot left AP on.

"Initially, until about 100 feet agl the take-off appeared normal but then the aircraft adopted an ever increasing nose-high attitude which culminated in a gentle left roll at about 300 feet agl before the aircraft's nose dropped sharply. It seemed to the aero club witnesses that the aircraft had stalled in a markedly nose-up attitude. After what appeared to be an attempted stall recovery at about 100 feet
agl, it dived into the ground whilst rolling left with the engine still running"
...
"During the ground evaluation tests it was noticed that if the ALT button was pressed, the autopilot
engaged... About three to four seconds
later, the elevator trim commenced winding on nose-up trim until it reached maximum deflection;
this took about 18 seconds".

HAL can get at you even in a 172.

https://assets.publishing.service.gov.uk/media/5422ec04e5274a13170000d5/dft_avsafety_pdf_501522.pdf
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Old 26th Apr 2019, 12:33
  #4363 (permalink)  
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wonkazoo, thanks for a thought provoking break from the regular arguments. Refreshing to have one's mind taken so vividly to that scene. Talking of minds.


A couple of times I've posted about getting into the minds of the three MAX crews. I've tried to paint the picture of the chaos and mental confusion that was probably - and I mean, probably - taking place.

Strangely, if feel Could've done's and should've done's are fine for analytical discussion . Yes, they're often unkindly critical, but without them we don't have both sides of the most fundamental part of this long thread: the argument between both camps. More or less the performance of the four pilots, V FAA and Boeing's behaviour.

I protested that the months of hindsight invalidates any true judgement we may feel compelled to put forward against the pilots.

Getting into the mind of an average pilot, whatever that might be these days. One thing's for sure, it's not one that's had his senses sharpened by months of focussed discussion on this specific crisis, and not necessarily comparable to some of the pilots on here that have a wealth of experience on a wide range of Boeing products.
I further expressed some astonishment at what I described as the dichotomy of opinions between even the highly experienced PPRuNe posters.
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Old 26th Apr 2019, 13:43
  #4364 (permalink)  
 
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wonkazoo,

Thank you for your excellent post, no need to apologise for its length. Like you, I have been to 'the edge' very early on in my airline pilot career, it made me think a whole lot differently about flying - to my eventual benefit. Indeed, yes, the brain does become scrambled for a while when something startling, sudden and frightening occurs. Read my link and stop for a moment and think how foolish we all were to switch off the main flight instruments in the middle of what was probably a spiral dive.
IFR conditions on the flight deck

It takes time to collect your thoughts and start to react correctly. I was the co-pilot. We survived and it made me very humble about these things ever afterwards. Armchair quarter backs should spare a thought for those caught up in such events and say to themselves,"There but for the grace of God go I."

And it applies to Sky Gods too!

Last edited by Bergerie1; 26th Apr 2019 at 14:02.
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Old 26th Apr 2019, 14:07
  #4365 (permalink)  
 
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Wonkazoo,

Appreciate the comments. Understanding the human reaction to an aircraft emergency is a very important part of examining these incidents. You're right, that it really isn't a case of Boeing messed up or the pilots messed up or the regulators messed up or the maintenance folks messed up. All those parts came together at the same time to cause these accident. However, by they same token, we can't simply sit back and say Boeing needs to fix their design, the FAA needs to strengthen their oversight, the airlines have to do a better job at training, and then turn a blind eye to what, we as professional pilots, ought to be doing to address obvious shortcomings in airmanship. And we can't address those shortcomings unless we acknowledge that those shortcomings were present in these accidents.

In my aviation career, I've had three incidents where if I didn't make the right choices in a timely manner, then a very bad outcome would have resulted. The most notable was an engine failure in a single-engine aircraft that culminated in a deadstick ILS approach to the runway with 300-1 weather. Yes, luck was involved in that there was an airport close enough to navigate to, but luck didn't land the plane. I don't say this to pat myself on the back, but to simply to say that I've been there. You're right in that the initial wave of emotions and disbelief can be enormous and potentially paralyzing. I've also made some embarrassing mistakes in my career that if not caught by my trusty First Officer, could have devolved into something unpleasant. Mistakes happen and humans err, but that does not mean we just throw up are arms and say there's nothing to be done.

I've said before that when I was an instructor pilot, I could take just about any well-adjusted adult and teach them the basics of flying and that they would be safe enough on a VFR day if nothing went wrong. Similarly, there are lots of people who can be taught the systems management approach to flying, and as long as nothing happens too quickly and the problem is well-known or the solution is covered by some non-normal checklist, then they will do just fine.

Here's the cold reality of these accidents: Things will happen that aren't on the checklist. They can happen quickly. Crew competency matters, and I do mean "crew" because the Captain can't do it all himself when things go bad. Basic airmanship skills matter. The ability to think under pressure matters. The ability to prioritize matters. Ultimately, these planes were flyable using some pretty basic airmanship skills, but that did not happen. Perhaps one day the aircraft and all the processes that touch a flight will be made so completely fault tolerant that these things don't matter. However, when that future becomes reality, airlines won't need professional pilots anymore, will they?

Yes, I'm being hard on the crew, just as I'm being hard on Boeing and the FAA and the airlines. It can be a hard business, and people die when we don't get it right. That being said, I've seen no evidence that anyone was intentionally malicious or careless. The human factor element touches every part of these accidents from the aircraft designers, to the supervisors, to the regulators, to the airline managers, and all the way to the flight crew. We know that there were multiple mistakes by multiple humans, and now it is incumbent on us to ask what could have been done differently. We do not do this so we have the luxury to say WE could have prevented these accidents, but to make the entire chain of causation more resilient and safer.

PPRuNe is not an online forum for Boeing or the FAA or airline management. We can point fingers, but we can't really fix their issues. PPRuNe, however, is a forum for professional pilots, so we can certainly discuss what ought to be done when we see evidence that points to lapses in airmanship. If some of the participants want to take the position that there is nothing to be done, that we merely have to accept that some of our number are going to succumb to the pressures induced by an unexpected aircraft state, fail to execute well-established procedures and/or apply basic airmanship skills, I am not sure what else I can say.

IMHO, what I think would be more beneficials is to move past the shock and denials and the strong desire to defend one of our own and look at the particular chain of causation that led to these crews not being able to perform to the standards of a professional pilot when lives were at stake.

Last edited by 737 Driver; 26th Apr 2019 at 17:03.
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Old 26th Apr 2019, 15:31
  #4366 (permalink)  
 
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737 Driver,

You are right too. Every part of that chain of human mistakes needs to be examined - manufacturers, regulators, airlines, trainers, accountants, managers and pilots. The pilots are the last link in that chain and in these last two accidents they were lacking too. As professional pilots we must strive for and achieve high standards, and, let's face it, most do.
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Old 26th Apr 2019, 15:50
  #4367 (permalink)  
 
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Originally Posted by 737mgm View Post
Another issue is, if these accidents were preventable by carrying out the required Boeing procedures or by applying basic flying skills respectively, despite MCAS activating.
When I was trained on the 737 (classic and NG), the stab trim runaway was a runaway - where the trim wheel ran continuously. We would identify it as a runaway, because it was continuously running, and flick the switches.

1. MCAS activation is not continuous, it's bursts.
2. The 737 trim system likes to provide bursts of random trim at certain times (STS) so bursts are considered normal.

This is why the Boeing excuse "they should have done the runaway stab QRH to fix the MCAS problem" is a load of utter nonsense. 737 Driver - pinning this on lack of airmanship will costs lives in the future.
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Old 26th Apr 2019, 15:56
  #4368 (permalink)  
 
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HundredPercentPlease,

I don't know the 737 but I used to fly 707s. The stab trim runaway drill was predicated on continuous movement as you say. I imagine the bursts of STS activity made these movements appear normal and thus mask the MCAS bursts too. All very confusing.
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Old 26th Apr 2019, 15:58
  #4369 (permalink)  
 
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Originally Posted by sky9 View Post
Can I just highlight that the F/O had 200hrs experience. I didn't get a commercial pilots licence until I had flown 230 hours and didn't fly jets until I had 1800hrs. The company that I flew 737's for in the UK in the early 1970's required 2000 hours before offering a job in the right hand seat.

This incident was to all intents and purposes a single pilot operation.
Absolutely spot on. At 200 (300 according to ET) hours, you are just along for the ride. The CA himself may have never flown anything outside of ET, certainly not old and broken airplanes from the past. It really bothers me that to this day, I sometimes look over at the FO for ideas or help in doing mental math, and he has nothing to contribute. These aircraft are certified for a minimum of two experienced pilots, not one instructor and one student. Ridiculous.

12,000 hours as captain of 727/57/67, I still rely on my highly experienced F/O's to feed me as much advice as they can.
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Old 26th Apr 2019, 15:59
  #4370 (permalink)  
 
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Originally Posted by HundredPercentPlease View Post
When I was trained on the 737 (classic and NG), the stab trim runaway was a runaway - where the trim wheel ran continuously. We would identify it as a runaway, because it was continuously running, and flick the switches.

1. MCAS activation is not continuous, it's bursts.
2. The 737 trim system likes to provide bursts of random trim at certain times (STS) so bursts are considered normal.

This is why the Boeing excuse "they should have done the runaway stab QRH to fix the MCAS problem" is a load of utter nonsense. 737 Driver - pinning this on lack of airmanship will costs lives in the future.
I think we disagree where a burst ends and continuously starts. Only been in the jumpseat of the 737, but I would be wildly surprised if STS would ever trim more than a second or two. Having the trim wheel run for ten seconds is way more than a burst. Having said that I can totally see the pilots not realizing what is going on amidst the whole set of stall warning/stick shaker/UAS indications. MCAS should never have been certified using only one AOA at a time, and I feel the same goes for the stall warning/stick shaker, there should at least be an easy way to cancel the alert if the warning is spurious.
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Old 26th Apr 2019, 16:04
  #4371 (permalink)  
 
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Originally Posted by sky9 View Post
Can I just highlight that the F/O had 200hrs experience. I didn't get a commercial pilots licence until I had flown 230 hours and didn't fly jets until I had 1800hrs. The company that I flew 737's for in the UK in the early 1970's required 2000 hours before offering a job in the right hand seat.

This incident was to all intents and purposes a single pilot operation.
This airline isn't alone in setting up that situation.
It does not help that the captain was only recently transitioned to the new aircraft, and the already-mentioned-a-few-hundred-times issues with "just what was in the differences training?" was hardly a robust aircraft systems course. That their best efforts were not good enough points, in my view, a finger at the system writ large: training, currency, company policies on training (and others) and of course the aircraft system itself. What is to me the most worrying is that with the comparatively recent Lion Air crash, this crew was, it seems, neither prepared nor trained on how to deal with that problem.
That right there, it seems to me, is where the entire system let these two pilots down. The "system" doesn't learn, and / or does a poor job of passing on "lessons learned."
Deni, a few pages back, points to the AoA signal getting to the flight computer as being a detail worthy of very thorough resolution. With the Lion Air ending up in the sea, some evidence of how that signal went sour may have been lost. In this crash, granted, there was a fire, perhaps some evidence of that signal's path, and it's possible sources of corruption, may be more clear.
I sincerely hope that Beoing's team is, along with their various test flights, putting a high magnification glass on the entire path of the AoA signal from vane to computer, and focues on how and where those signals can get dirty/contaminated. I experienced a variety of strange things happening in aircraft over the years due to electrical signals going astray or strange. Were stray trons a root cause?
We'll see.
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Old 26th Apr 2019, 16:13
  #4372 (permalink)  
 
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Originally Posted by HundredPercentPlease View Post
When I was trained on the 737 (classic and NG), the stab trim runaway was a runaway - where the trim wheel ran continuously. We would identify it as a runaway, because it was continuously running, and flick the switches.

1. MCAS activation is not continuous, it's bursts.
2. The 737 trim system likes to provide bursts of random trim at certain times (STS) so bursts are considered normal.
Honest question: How long does a trim wheel have to spin before you deem it "continuous" and thus subject to intervention by the pilot?

In the case of Ethiopian, the MCAS input was not like the normal Speed Trim you see during takeoff. If you take a look at the DFDR traces of the automatic trim before the flaps were retracted, you can see what these inputs look like. Short and seemingly random inputs.

When MCAS activated, it ran the trim nose down for 9 continuous seconds. Please count that out to yourself. MCAS moved the stab about 2.5 degrees. That would be about 37 spins of the flight deck trim wheel. Please imagine that white stripe on the trim wheel making 37 trips passed the Captain's knee. All this time, the Captain was holding the yoke and must have felt the changing trim pressures. This happened TWICE (one other MCAS input was interrupted by the pilot trimming nose up). Ultimately, it wasn't even the 8122-hour Captain who suggested that the trim cutout switches be used - it was the 361-hour First Officer.

So honestly, just how long does the stab have to continuously run before a fully qualified 737 type-rated Captain determines that he has runaway stab trim?
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Old 26th Apr 2019, 16:42
  #4373 (permalink)  
 
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Reviewing the charts, can someone explain to me why the N1 percentage seems to be 95-100%? This aircraft seems to be going at a very high IAS. No wonder manual trim was so difficult. Rule number 1, fly the aircraft.
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Old 26th Apr 2019, 16:45
  #4374 (permalink)  
 
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Salute!

Thanks a lot, Wonk. Best post in a very long time.

Maybe some of the “Sky Gods” here would think about some things.

And I support your criticism of Big B and FAA and so forth for letting the plane fly we lowly proles without satisfying basic aerodynamic FAR requirements. I would even go so far as to claim the Airbus FBW models could be flown in “direct law” and behave as required. After all, the AF447 debacle showed how stable the plane was despite the best efforts of the crew to keep it stalled.

Gums ......
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Old 26th Apr 2019, 17:31
  #4375 (permalink)  
 
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Gums,

As I understand it, when designing the A320 Airbus toyed with the idea of reduced stability, citing FBW as the "excuse". The whole world raised a regulatory eyebrow and Airbus designed a fully stable aircraft.

Ironically, Boeing designed a less than stable aircraft with a bit of bolt on, undocumented FBW, and the world continued to rotate, until two crashed.
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Old 26th Apr 2019, 17:41
  #4376 (permalink)  
 
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Originally Posted by 737 Driver View Post
). Ultimately, it wasn't even the 8122-hour Captain who suggested that the trim cutout switches be used - it was the 361-hour First Officer.
The reason people are bashing your skygod/airmanship analysis is hidden in your statement above.

Why do you think the captain didn't get it, but the FO did?

Really, why?

As so many are saying, this is HF. Think: volume of input and processing.

A final thought: do you think that if the ET crew had trained this scenario in the sim, then when it happened for real then they would have been fine? The comfort of the sim helps recognition, which reduces processing, which allows improved performance through lack of overload. The max is a dog, but Boeing would have got away with it (again) if pilots had been sim trained.

These pilots were overloaded, they weren't adequately prepared and the aircraft is flawed.
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Old 26th Apr 2019, 17:47
  #4377 (permalink)  
 
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Originally Posted by HundredPercentPlease View Post
.
These pilots were overloaded, they weren't adequately prepared and the aircraft is flawed.
Agree 100%. So what should be done to insure the next crew is not overloaded and unprepared the next time they are handed a flawed, but still flyable, aircraft?

Because there will be a next time.



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Old 26th Apr 2019, 17:57
  #4378 (permalink)  
 
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Simple.

Remove the flaw. Either remove the aerodynamic stability problem or make the FBW fix a proper one (like an Airbus, triple inputs, 14 computers, multiple layers of automatic or selectable degraded flight modes).

Train the pilots. If a single failure (here AoA) causes a monster, then prepare the pilots by training.

As someone who has moved back and forth, twice, between the 737 and A320, I can't begin to describe how lowly I view the Renton tractor. Boeing made a flawed aircraft and failed to mandate sufficient training. The pilots are as much victims as the passengers. No doubt at all.
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Old 26th Apr 2019, 18:07
  #4379 (permalink)  
 
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Originally Posted by 737 Driver View Post
Wonkazoo,
Ultimately, these planes were flyable using some pretty basic airmanship skills, but that did not happen.
No.
Look I agree with most of what you're saying. Good airmanship, hand flying practice, all the other great points.

But this is different to any other aircraft system failure that I can think of.

Eg loss of pitot. Loss of static. Engine fire. "QF32" uncontained failure causing multiple control system failures. Flap/slat wrong config at takeoff. Dual engine out after bird strike... Etc.

These are all single events that put the aircraft in a new and interesting state. Now use good airmanship to recover. Fine.

Why is MCAS different?
1) It's intermittent. Not just a single event. Pops up unexpectedly for a few seconds then disappears. These are always the hardest faults to diagnose.
2) It's insidious - hidden by noise and by human expectation (hiding in plain sight - bursts of trim are normal).
3) It's fast - it can put you in serious trouble in a few seconds flat
4) Like a bacterial complication to a viral infection, it creeps in and hits you when you're dealing with another problem (airspeed unreliable/stick shaker)
I'm not saying that the ET302 pilots had no room for improvement. Like you I think their repeated autopilot engagement is a red flag. But dealing with MCAS failure is in test pilot league, not 'basic airmanship skills'.
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Old 26th Apr 2019, 19:31
  #4380 (permalink)  
 
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Inherent stability and "help

Salute!

@ 100% We went thru a lot of the issue concerning stability and such on the 447 thread.

The more we saw of the AB330, and the FDR traces, the more it was apparent that the thing was and is a good design. So smooth an entry to the stall that the crew did not understand why the sucker wasn't reponding to stick commands.

Many of the bent wing designs have obvious clues when you are gettiing to high AoA. Buffet, wing rock, maybe aileron reversal and so forth. Others are smooth and stick shakers or pushers can save the day.

The AB330 does not appear to be statically neutral from what we saw, but the control laws make it appear so. If you use a gee command for pitch, then you will not have speed stability WRT AoA or Q. Duhhhh? Then I see the 737 with the STS kludge and I cannot find enuf early 737 data to indicate a need for the STS when the dinosaur model was certified.

One and not the only reason that a good FBW implementtion helps the $$$, is you can fly with less trim drag by using the stab to keep the tail up than forcing the nose down. My trusty Viper was and is the classic case. However, I do not think that Airbus developed the 320 and subsequent FBW models to be inherently speed neutral or have much longitudinal stability issues. Sure, you could get away with some aft cee gee, but could always fly the plane as you would any other. I"m not even sure if the USAF F-22 and F-35 have the same longitudinal stability properties as the F-16. Their demo routines show stuff that we Viper drivers couldn't dream of, primarily the really high AoA stuff.

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