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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 25th Mar 2019, 19:48
  #2521 (permalink)  
 
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Originally Posted by MemberBerry View Post
Until we get the final reports from the investigating teams, it's the other way around: WE don't know exactly what those crews were doing.

I'm not saying those pilots didn't make mistakes, it's quite possible they did, after all it was a stressful and confusing situation. It would actually be surprising if they did everything perfectly.

But so far I didn't see any evidence suggesting a training deficit of those pilots, compared to pilots from other airlines. If that's true, it means it is not impossible this could have happened to pilots from US or European airlines. There are even some people that claimed it couldn't have happened to European and US crews, because of their better training. I think we don't have enough evidence, and it's way to early for such claims.
I think that point of view is exactly right. More importantly even than to know what those flight crews were doing is to make a useful theory of why they did what they did. After we figured out what they did, which should be relatively straightforward from the recordings.

The very few cases of suicide notwithstanding, it is practically always the case that to professional operators suffering an accident (pilots, ship captains, train drivers, excavator operators, chemical plant engineers, ...) what they were doing made sense at the time. Only with hindsight does it seem obvious that it was wrong, and once we know the "correct" solution it seems impossible to miss. But we cannot really evaluate the situation they were in at the time.

I hope Professor Dekker won't mind if I use a small picture from his highly recommended book The Field Guide to Understanding "Human Error" (quotes original) to illustrate:


(2009 Sidney Dekker)


Bernd
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Old 25th Mar 2019, 20:01
  #2522 (permalink)  
 
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Question for the pros from a private pilot (and sorry if this was answered in the thread and I didn't see it):

How often do flight crews experience a stall warning (stick shaker, aural warning, etc) in normal Part 121 flying? I would guess it's very rare.
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Old 25th Mar 2019, 20:10
  #2523 (permalink)  
 
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Originally Posted by kenish View Post
Question for the pros from a private pilot (and sorry if this was answered in the thread and I didn't see it):

How often do flight crews experience a stall warning (stick shaker, aural warning, etc) in normal Part 121 flying? I would guess it's very rare.

Never.

In the EASA environment it should be trained regularly during the OPC/ProfCheck in the SIM.
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Old 25th Mar 2019, 20:14
  #2524 (permalink)  
 
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Originally Posted by kenish View Post
How often do flight crews experience a stall warning (stick shaker, aural warning, etc) in normal Part 121 flying? I would guess it's very rare.
Frequently, every 6 months in simulator sessions, never in line flying.
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Old 25th Mar 2019, 20:28
  #2525 (permalink)  
 
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Originally Posted by kenish View Post
Question for the pros from a private pilot (and sorry if this was answered in the thread and I didn't see it):

How often do flight crews experience a stall warning (stick shaker, aural warning, etc) in normal Part 121 flying? I would guess it's very rare.
Even in a C-172 I would not normally have any stall buffeting or warnings going on with paying passengers. They tend not to like it If you are a recent PPL, stalls seem like so much of your recent training it might seem odd you can not stall any airplanes for months or years if you don't want to, checkrides of various types excepted.
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Old 25th Mar 2019, 20:34
  #2526 (permalink)  
 
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https://www.aopa.org/news-and-media/...-boeing-crisis
>>
When the Lion Air crash of a Boeing 737 MAX 8 revealed the existence of a flight control system operating in the background, which Boeing and the FAA had not revealed when the MAX 8 was introduced, pilots felt betrayed, as if Boeing had secretly abandoned its guiding design principle and lost faith in pilot skills. In actuality, Boeing’s trust in pilot skills likely buoyed a system design and roll-out strategy that appears to be at the root of two recent MAX 8 crashes. Boeing’s critical mistake may be in assuming a worldwide standard of pilot competency that doesn’t exist.
>>
I ran across this today. One theory is that of course American pilots are good enough to deal with runaway trim, so Boeing figured no big deal
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Old 25th Mar 2019, 20:52
  #2527 (permalink)  
 
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Originally Posted by island_airphoto View Post
https://www.aopa.org/news-and-media/...-boeing-crisis
>>
When the Lion Air crash of a Boeing 737 MAX 8 revealed the existence of a flight control system operating in the background, which Boeing and the FAA had not revealed when the MAX 8 was introduced, pilots felt betrayed, as if Boeing had secretly abandoned its guiding design principle and lost faith in pilot skills. In actuality, Boeing’s trust in pilot skills likely buoyed a system design and roll-out strategy that appears to be at the root of two recent MAX 8 crashes. Boeing’s critical mistake may be in assuming a worldwide standard of pilot competency that doesn’t exist.
>>
I ran across this today. One theory is that of course American pilots are good enough to deal with runaway trim, so Boeing figured no big deal
Here we are 15 days and 2500+ posts into a thread about an accident for which we have not yet seen the FDR info nor heard anything about the crew conversations from the CVR and we are already saying that system design and roll-out strategy appears to be at the root of that accident?! We need that data before any sense of the root cause can be put forth as anything other then conjecture. Without the Lion Air accident we would at this point have no idea what brought the Ethiopian 737MAX down. As a result of having had the Lion Air accident many people seem to assume that the Ethiopian event was a repeat.

Can anyone with direct knowledge of what the Ethiopian FDR reveals describe specifically how and why then think this accident is similar to the Lion Air accident in a manner that would point to "system design and roll-out strategy" as having played a role?
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Old 25th Mar 2019, 20:58
  #2528 (permalink)  
PJ2
 
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Smile

Originally Posted by bsieker View Post
I think that point of view is exactly right. More importantly even than to know what those flight crews were doing is to make a useful theory of why they did what they did. After we figured out what they did, which should be relatively straightforward from the recordings.

The very few cases of suicide notwithstanding, it is practically always the case that to professional operators suffering an accident (pilots, ship captains, train drivers, excavator operators, chemical plant engineers, ...) what they were doing made sense at the time. Only with hindsight does it seem obvious that it was wrong, and once we know the "correct" solution it seems impossible to miss. But we cannot really evaluate the situation they were in at the time.

I hope Professor Dekker won't mind if I use a small picture from his highly recommended book The Field Guide to Understanding "Human Error" (quotes original) to illustrate:


(2009 Sidney Dekker)
Bernd
Hi Bernd;
I'm sure Professor Dekker won't mind a bit!

As you'd know, he also states, "What (you think) should've happened cannot explain people's behaviour", (The Field Guide to Understanding "Human Error" - Dekker, Ashgate, 2006). In fact, rather than possessing pilot licences, this specific book among all of Dekker's excellent works should be required reading as a condition of PPRuNe participation! ;-)

BTW, I fully agree with you regarding your views on AoA. AoA is for downstream equipment to use. Even though it appears to be obvious, I don't think AoA is the magic bullet some make it out to be and I don't think the case has been demonstrated for it's inclusion in an already-crowded PFD. In fact, there are no saves on record that occurred as a result of pilots knowing their AoA.

The question is, why did two AoA sensors, the one from the flight previous to the accident flight, and, (after having been changed), the accident flight AoA sensor have the same, identical incorrect AoA value? I've looked in the AMM - the installation is "keyed" so an incorrect install is unlikely, and the test procedures are thorough. Even if, hypothetically, not done, I am informed that these sensors are rarely wrong. Also, while poor operation of the loading bridge can possibly damage the left AoA, all such instances have been caught on the walkaround. (For those who don't know the aircraft, the AoA sensor is well forward of the L1 door).

PJ2

Last edited by PJ2; 26th Mar 2019 at 06:33. Reason: strike out incorrect statement re JT610 AoA sensor replacement
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Old 25th Mar 2019, 21:18
  #2529 (permalink)  
 
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Originally Posted by safetypee View Post
Why would any operator need to experience a Lion MCAS event if the purpose of the ‘fix’ is to prevent such a failure, or at least its severity.
There's no evidence that MCAS was implemented to prevent any failure which befell Lion Air. That is, no one has yet suggested the Lion Air crash was caused by a stall, which is what MCAS was designed to prevent.
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Old 25th Mar 2019, 21:19
  #2530 (permalink)  
 
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Originally Posted by PJ2 View Post

The question is, why did two AoA sensors, the one from the flight previous to the accident flight, and, (after having been changed), the accident flight AoA sensor have the same, identical incorrect AoA value?

PJ2
You need to reread the preliminary report on JT610. The left AOA sensor was replaced prior to JT043 on the evening prior to the crash. Despite its malfunction on that flight, it was neither written up nor replaced prior to JT610 the next day.
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Old 25th Mar 2019, 21:44
  #2531 (permalink)  
 
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Originally Posted by FCeng84 View Post
Here we are 15 days and 2500+ posts into a thread about an accident for which we have not yet seen the FDR info nor heard anything about the crew conversations from the CVR and we are already saying that system design and roll-out strategy appears to be at the root of that accident?! We need that data before any sense of the root cause can be put forth as anything other then conjecture. Without the Lion Air accident we would at this point have no idea what brought the Ethiopian 737MAX down. As a result of having had the Lion Air accident many people seem to assume that the Ethiopian event was a repeat.

Can anyone with direct knowledge of what the Ethiopian FDR reveals describe specifically how and why then think this accident is similar to the Lion Air accident in a manner that would point to "system design and roll-out strategy" as having played a role?
Hi there FCeng
I realise that this thread is called Ethiopian ....... etc but it seems to be really about both accidents.
As far as I know nobody has that information other than the French BEA and presumably the Ethiopian authority. Assuming the recorders were not damaged. And nothing has been revealed so far. We don't know if the failure modes were the same or what the crew response was. Do we? Like you I am keen to know.
It seems a long delay between getting the FDR to France and the release of any data.
Has it been suggested somewhere here that we know what happened to Ethiopian? The Lion Air prelim. report is out and I thought that we were discussing that one in some detail, since we know a lot of what happened. And the rest about Ethiopian speculation?
The way aviation stays safe is for us to learn from every incident, find out what happened immediately and ensure that everyone knows how to avoid that particular trap next time. So, we have the flight the day previous to the Lion Air crash, , which may have provided valuable lessons perhaps. We shall see. There may, I say may since all flights of the Max since it came into service have live Flight Data Recording which would l am pretty sure throw up and previous examples of this sort of failure mode. Or MOR pilot reports of similar events. It would be very sad if others had experienced the same events, successfully dealt with them however difficult, and not passed on that knowledge into the gene pool.
Ethiopian did have some knowledge because they issued a notice to all their pilots referring to Lion Air and the Boeing advice. But the failure mode may have been completely different could it not?
If you read through some of the 2500 odd posts , a lot of them are cut and paste from Internet, Newspaper " sources" and other media feeds. Some of the commentary is first class but it can be hard for readers sometimes to sort through it. And then some things have been fully discussed days or weeks ago, only to resurface because we have not had time to read the whole 2500 posts. That is the nature of these forums.
But I have learned a lot over the last few days about the functioning of these systems, regulatory oversight, and probably most important, how many different views there are out there. All valuable. Except Boeing bashing in my view. The historic accident rate for Boeing is very low and pretty much the same as Airbus.
Let us all hope that the reports will reveal what happened in full detail and permit the 737 Max back where it belongs. With any shortcomings in any system, human or mechanical or electronic sorted out.

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Old 25th Mar 2019, 21:51
  #2532 (permalink)  
 
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Originally Posted by BobM2 View Post
Frequently, every 6 months in simulator sessions, never in line flying.
I can think of quite a few including a 747 at XXX stalling in the holding pattern 7000 feet, and good stall recovery but, very close call with planes below. I will look for others but I think there are many.
Turkish at AMS comes to mind right away
Cheers
Y
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Old 25th Mar 2019, 22:11
  #2533 (permalink)  
 
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Originally Posted by Ian W View Post

They have a lot of confidence rebuilding to do. It would seem there is a lot of hostility too.
Boeing first needs to get over the first high hurdle of gaining confidence in MCAS. As a former aviation safety assessor, I find it incredulous that even if Boeing had decided the MCAS software was only DO-183C Level C (when the evidence now shows it should have been Level A), there was still no-one in their organisation (from QA to coders) who pointed out having software directly control the stabiliser based on the use of only one sensor is a very bad idea! Perhaps someone did and they were told (in no uncertain terms), ‘the pilot will cope’. Perhaps ‘someone’ suggested it might be a good idea if MCAS was disabled when GPWS was active or altitude was less than, say 500 feet, but was ignored. I have little confidence in the robustness of the MCAS software to the extent that I think it could now be a ‘prime suspect’. The probability of the same hardware failing on three different flights, especially as on JT043 no fault was found, seems to me unlikely. The MCAS software might not have been thoroughly scrutinised and tested for possible software self corruption, overflows, processor overload, never ending loops, interrupts clashing etc, etc. It could be that a large value of AoA caused a value overflow in the software leading to arbitrary behaviour of the MCAS. However, whatever the root cause of the failure turns out to be, the problem still remains that a non Level A software package can control the stabiliser. Regardless of whatever patch(s) are introduced, at some time in the future there is an unacceptable probability that a bug could emerge causing the MCAS to continually demand a ‘nose down’.
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Old 25th Mar 2019, 22:15
  #2534 (permalink)  
 
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Originally Posted by yanrair View Post
I can think of quite a few including a 747 at XXX stalling in the holding pattern 7000 feet, and good stall recovery but, very close call with planes below. I will look for others but I think there are many.
Turkish at AMS comes to mind right away
Cheers
Y
Sure, AF447 & China 747 at high altitude, Asiana on short final at SFO, competent aviators NEVER!
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Old 25th Mar 2019, 22:18
  #2535 (permalink)  
 
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Originally Posted by MemberBerry View Post
I feel there is also discomfort among some others on this forum to accept that even pilots that "know what they are doing" might not have been able to save the Lion Air or the Ethiopian flights.

My discomfort is with the constant claims that a "competent pilot" would have identified and solved the problem immediately, and the insinuations that the crews from those two flights "didn't know what they were doing".

Until we get the final reports from the investigating teams, it's the other way around: WE don't know exactly what those crews were doing.

I'm not saying those pilots didn't make mistakes, it's quite possible they did, after all it was a stressful and confusing situation. It would actually be surprising if they did everything perfectly.

But so far I didn't see any evidence suggesting a training deficit of those pilots, compared to pilots from other airlines. If that's true, it means it is not impossible this could have happened to pilots from US or European airlines. There are even some people that claimed it couldn't have happened to European and US crews, because of their better training. I think we don't have enough evidence, and it's way to early for such claims.
Yes indeed. I have seen such commentary. It is premature and totally unproven. What I have said, I think, is that a runaway STAB whether continuous or intermittent (stop/start but always nose down) is containable - from a purely piloting / mechanical / aerodynamic point of view. If it is noticed it can be stopped. STAB OFF switches.
That is a fact, and it happened the day before. And of course the recent Boeing simulator sessions with line pilots at Seattle showed that they all stopped it. But of course, they knew what to expect, didn't they. But they were 737-max airline pilots and not Boeing test pilots.
Y
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Old 25th Mar 2019, 22:21
  #2536 (permalink)  
 
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Thanks for that reminder Bob. It is late and I am too tired to start Googling. The point here is that these things happen a lot more than people think and normally, the pilot can manage it.
Y
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Old 25th Mar 2019, 22:26
  #2537 (permalink)  
 
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Originally Posted by BobM2 View Post
Sure, AF447 & China 747 at high altitude, Asiana on short final at SFO, competent aviators NEVER!
I would add Thomsonfly Bournemouth. A company that prides itself on the training and quality of their pilots but this one was very close to a hull loss following a thoroughly mismanaged stall event.
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Old 25th Mar 2019, 23:00
  #2538 (permalink)  
 
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Accident Investigation Rules

Most people are not aware of the international rules & protocols governing investigations of air transport accidents. The assigned lead investigating agency of a particular accident is the only one who can make public comment on the details of that investigation. In the case of ET302, the lead agency is Ethiopian Civil Aviation Authority. Any public comment concerning findings of the investigation must come only from them. Any of the other participants, Ethiopian Airlines, Boeing, FAA, NTSB, BEA, CFM, etc, who violates this rule will be immediately barred from further participation. So if some of the statements made by participants such as FAA or Boeing seem rather vague, that is the reason. A preliminary report is supposed to be issued within 30 days, which was done by Indonesia for the Lion Air crash.
The Ethiopian Airlines CEO was just quoted on TV news as saying a preliminary report should be out either this week or next, so stay tuned.
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Old 25th Mar 2019, 23:02
  #2539 (permalink)  
 
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Originally Posted by FCeng84 View Post
Can anyone with direct knowledge of what the Ethiopian FDR reveals describe specifically how and why then think this accident is similar to the Lion Air accident in a manner that would point to "system design and roll-out strategy" as having played a role?
It is quite possible that MCAS had nothing to do with either accident, but the existence of this poorly designed feature does point to a flawed "system design and roll-out strategy." I have debugged complex systems (both software and electrical) and quite frequently the close review of the system reveals design faults that unfortunately turn out not to have anything much to do with the actual problem that you were tasked to fix. MCAS is glaringly bad, the question that pilots and passengers should ask is "what else don't we know about?" That something else might be the real culprit.

For all we know, something else is going on -- I do not like the reports of data corruption that threw fault codes, attempted to be fixed by "cleaning the connectors." Random data presented to software can expose all sorts of bugs, including in the recording systems that we are using to try to analyze this situation. I worked with a former Boeing programmer (not on avionics) and his code was not exactly fault tolerant with respect to bad network packets; hardware/software engineers seem to have a mindset that precludes the possibility of bad data being presented to their code.
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Old 25th Mar 2019, 23:53
  #2540 (permalink)  
 
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Originally Posted by Water pilot View Post
It is quite possible that MCAS had nothing to do with either accident, but the existence of this poorly designed feature does point to a flawed "system design and roll-out strategy." I have debugged complex systems (both software and electrical) and quite frequently the close review of the system reveals design faults that unfortunately turn out not to have anything much to do with the actual problem that you were tasked to fix. MCAS is glaringly bad, the question that pilots and passengers should ask is "what else don't we know about?" That something else might be the real culprit.

For all we know, something else is going on -- I do not like the reports of data corruption that threw fault codes, attempted to be fixed by "cleaning the connectors." Random data presented to software can expose all sorts of bugs, including in the recording systems that we are using to try to analyze this situation. I worked with a former Boeing programmer (not on avionics) and his code was not exactly fault tolerant with respect to bad network packets; hardware/software engineers seem to have a mindset that precludes the possibility of bad data being presented to their code.
This is spoken like someone who understands the interaction between hardware and software. It's exactly what I wondered, as well. Sure, maybe it's as simple as altering the sensor inputs, but the input itself, wherever it comes from, has to be trusted all the time. If input is suspect, then output is too, and that's a cause for concern.
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