Go Back  PPRuNe Forums > Flight Deck Forums > Rumours & News
Reload this Page >

Ethiopian airliner down in Africa

Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots.

Ethiopian airliner down in Africa

Old 30th Apr 2019, 16:01
  #4641 (permalink)  
 
Join Date: Apr 2009
Location: Hotel Gypsy
Posts: 2,830
Originally Posted by alf5071h
These people, like pilots, are Children of The New Age’, many not even born before the 737 first flew.

The 737 first flew 9 days after I was born so, at 52 years old, I'm rather pleased I fall on the right side of the line. However, my wife would probably agree with your 'children' sentiment.
Cows getting bigger is offline  
Old 30th Apr 2019, 16:06
  #4642 (permalink)  
 
Join Date: Jul 2003
Location: An Island Province
Posts: 1,103
737 Driver, #4683
You can't fix a problem until you recognize a problem exists. I humbly suggest that we collectively recognize the crew competency issues within our own ranks and devote our brain cells to addressing that problem rather than lobbing largely ineffectual grenades over the fence.’

You can be as humble as you like, but if the problem is within human thought, that there is a limit to human performance, then the competency issue resides with our (your) thoughts - Ethiopian airliner down in Africa

Hopefully you accept that there is a limit; then how is this defined, by whom. Can you enlighten us, where is the evidence of crew competency problems, particularly relating to these accidents.
Or do you use outcome - an accident, to judge competency after the fact.

How might we judge the competency of designers, regulators. With hindsight all appear deficient, but in reality everyone working as best they could, in the conditions they faced; how might they describe their conditions of work and change them.

What the industry requires is the wisdom to foresee how crews will react in extreme, rare, surprising, and life threading situations; without such vision, then crews require help in avoiding these extremes, avoid the situation, change the overall operating environment - change the aircraft system.

Heed the words of James Reason; “it’s very difficult to change the human condition, but you can change the conditions of work”.
alf5071h is offline  
Old 30th Apr 2019, 16:17
  #4643 (permalink)  
 
Join Date: Apr 2019
Location: USA
Posts: 217
Originally Posted by alf5071h View Post
.
Can you enlighten us, where is the evidence of crew competency problems, particularly relating to these accidents.
I am just going to accept at face value that you haven't read my previous posts. Both I and other participants have commented on this extensively, perhaps too extensively for some people's tastes. Perhaps you should take a moment and review those posts?
737 Driver is offline  
Old 30th Apr 2019, 16:37
  #4644 (permalink)  
 
Join Date: Mar 2015
Location: Washington state
Posts: 210
Originally Posted by Fortissimo View Post
Interesting and very carefully chosen words in Boeing's statement https://boeing.mediaroom.com/news-re...ts?item=130426, issued in response to media reports yesterday.



It goes on to state that if you did not opt for the AOA display, your disagree alert was "not operable". However, there will be an optional service bulletin to tell you how to make it operable on aircraft already delivered. So that's OK then.
Isn't it amazing how Boeing's engineering is never wrong, it is just that the customers do not understand it. I should look up and see if some of my old management colleagues work there, this BS is so familiar (although we did it better.)
Water pilot is offline  
Old 30th Apr 2019, 17:13
  #4645 (permalink)  
 
Join Date: Feb 2008
Location: Apple Maggot Quarantine Area
Age: 43
Posts: 64
Originally Posted by Water pilot View Post
Isn't it amazing how Boeing's engineering is never wrong, it is just that the customers do not understand it. I should look up and see if some of my old management colleagues work there, this BS is so familiar (although we did it better.)
How did you arrive at that interpretation of the press release? Because I arrived at the exact opposite conclusion. Boeing has admitted that they screwed up by tying the activation of the AOA Disagree alert to the the selection of the AOA indicator customer option.

I don't see any language in the release that insinuates that this was in any way the customer's fault or that it is to a lack of the customer's understanding.
slacktide is offline  
Old 30th Apr 2019, 17:28
  #4646 (permalink)  
 
Join Date: Nov 2007
Location: dublin
Posts: 1
Originally Posted by Cows getting bigger View Post
The 737 first flew 9 days after I was born so, at 52 years old, I'm rather pleased I fall on the right side of the line. However, my wife would probably agree with your 'children' sentiment.
Sometimes here we forget that the 737 basic design is actually 1950s since it’s a 707 with two engines missing. When I transferred from 707 to 737 you could nearly have done a differences course! Ok no flight engineer but systems almost the same including the STAB TRIM which is unchanged in basic concept for 60+
now. The 707 had no hydraulic controls except rudder boost and even that was not needed. We had no proper simulator so a lot of training was done on a real plane including stab runaway/ emergency descent from high level and engine failures.
So, when the Max returns to the skies and
ends up with a life of several decades, it will be a century old design with a few electronic add ons when it finally retires.
Y
yanrair is offline  
Old 30th Apr 2019, 17:51
  #4647 (permalink)  
 
Join Date: May 2010
Location: Boston
Age: 68
Posts: 439
Originally Posted by slacktide View Post
How did you arrive at that interpretation of the press release? Because I arrived at the exact opposite conclusion. Boeing has admitted that they screwed up by tying the activation of the AOA Disagree alert to the the selection of the AOA indicator customer option.

I don't see any language in the release that insinuates that this was in any way the customer's fault or that it is to a lack of the customer's understanding.
Agreed that they dont blame the customer in this one, but they seem to just not be able to help themselves when it comes to trying to have it both ways, my bold in quote from release.

Boeing included the disagree alert as a standard feature on the MAX, although this alert has not been considered a safety feature on airplanes and is not necessary for the safe operation of the airplane. Boeing did not intentionally or otherwise deactivate the disagree alert on its MAX airplanes.

The disagree alert was intended to be a standard, stand-alone feature on MAX airplanes. However, the disagree alert was not operable on all airplanes because the feature was not activated as intended.
Reminds me of the classic "a mistake was made" in place of "i made a mistake".
As to safety it would have helped prevent Lion air since it would have flagged AoA on penultimate flight.
MurphyWasRight is offline  
Old 30th Apr 2019, 18:54
  #4648 (permalink)  
 
Join Date: Feb 2008
Location: west susssex uk
Age: 76
Posts: 5
Does anyone on this topic know about Boeings system design ? and if so can they please explain to this simple pilot why mcas was designed in the waay it was, If I understand correctly MCAS is a sub-system designsd solely to counteract the lift generated by the engine nacelles at higher than normal AOT. It does this by trimming the stab nose down meaning that if the MCAS system fails due to incorrect AOA info, unless corrected by the PF its heading for disaster.
Why did they not simply alter the elevator feel circuit so that higher force was required to pull back on the stick, sorry column if the AOT was too high and the stick forces were reducing due to the nacelle lift
This could surely have been done so that forward ie nose down column movement was not affected.
This would mean that what ever happened the aircraft would not be left with a nose down trim and would not therefore be trying to fly into the ground.
rodlittle is offline  
Old 30th Apr 2019, 19:20
  #4649 (permalink)  
 
Join Date: Feb 2015
Location: The woods
Posts: 1
Originally Posted by rodlittle View Post
Does anyone on this topic know about Boeings system design ? and if so can they please explain to this simple pilot why mcas was designed in the waay it was, If I understand correctly MCAS is a sub-system designsd solely to counteract the lift generated by the engine nacelles at higher than normal AOT. It does this by trimming the stab nose down meaning that if the MCAS system fails due to incorrect AOA info, unless corrected by the PF its heading for disaster.
Why did they not simply alter the elevator feel circuit so that higher force was required to pull back on the stick, sorry column if the AOT was too high and the stick forces were reducing due to the nacelle lift
This could surely have been done so that forward ie nose down column movement was not affected.
This would mean that what ever happened the aircraft would not be left with a nose down trim and would not therefore be trying to fly into the ground.
Rod,
There are about four of us on this thread who think that. So you are in good company.
Boeing has a history of faffing with stab trim to compensate feel inputs and to them I guess it came naturally.
However, a fail mode in the control feel or a separate dedicated feel box would only cause a harder pull - once - and could be trimmed out.
That is what should have been installed (says I) and even if retrofitted may well be:
- cheaper than losing public trust
- easier to explain to the world and the pilots
- a much less critical system than MCAS can become.
B
bill fly is offline  
Old 30th Apr 2019, 19:29
  #4650 (permalink)  
 
Join Date: Aug 2013
Location: Washington.
Age: 69
Posts: 506
Originally Posted by slacktide View Post
How did you arrive at that interpretation of the press release? Because I arrived at the exact opposite conclusion. Boeing has admitted that they screwed up by tying the activation of the AOA Disagree alert to the the selection of the AOA indicator customer option.

I don't see any language in the release that insinuates that this was in any way the customer's fault or that it is to a lack of the customer's understanding.
Regardless of the presence of a AOA disagree alert, the system had the data with which to disarm MCAS. Boeing’s recent statements that nothing was wrong with the design has already twice been disproven. And it’s wrong for at least two reasons, use of a single AOA sensor, the second, that when AOA sensors disagree, the MCAS is not disarmed.
GlobalNav is offline  
Old 30th Apr 2019, 20:19
  #4651 (permalink)  
 
Join Date: Aug 2012
Location: Scotland
Age: 50
Posts: 168
Originally Posted by bill fly View Post
There are about four of us on this thread who think that.


Count me in on that!

Nothing that some year dot bicycle technology (much like the rest of the flight control system) couldn't have resolved with simplicity, redundancy & no additional training requirements - it's considering this that make me wonder far more broadly about MCAS.
Thrust Augmentation is offline  
Old 30th Apr 2019, 20:40
  #4652 (permalink)  
 
Join Date: Aug 2007
Location: Alabama
Age: 54
Posts: 365
Originally Posted by GlobalNav View Post


Regardless of the presence of a AOA disagree alert, the system had the data with which to disarm MCAS. Boeing’s recent statements that nothing was wrong with the design has already twice been disproven. And it’s wrong for at least two reasons, use of a single AOA sensor, the second, that when AOA sensors disagree, the MCAS is not disarmed.
The wiring diagram of the MCAS/STS is very eloquent. The pilots have no way to disarm the MCAS/STS. Is either both ON or CUT OFF, which means also thumb switches are disabled if in CUT OFF position. NG wiring diagram shows that STS could have been disarmed by one of the switches, keeping operative the thumb switches.
FrequentSLF is online now  
Old 30th Apr 2019, 21:01
  #4653 (permalink)  
 
Join Date: Jan 2008
Location: uk
Posts: 793
Originally Posted by Cows getting bigger View Post
Dare I say it, but the differences between A & B philosophy really show here. In the early days of A, I was like many pilots - dubious and wary of automation. Over a generation of flying later we seem to have got our head around they fact that HAL(A) has matured, is now rather good at his job and, generally speaking, our side of the house only gets into trouble when we ignore HAL(A). Meanwhile, HAL(B) appears to still be at school and capable of having hissy-fits, just like my teenage daughter.
I think that is unfair to Boeing - B has had a proper grown up HAL since 777 and many think it is superior to the A model (certainly it came after and learned from it). From an engineering point of view (I accept that pilots may have a preference) there isn't much to choose between C* and C*U, sidesticks or yokes - both systems work and are well proven now.

What was clear to this engineer was the difference in philosophy between A & B Hals - HAL(A) will protect the pilot from him/herself overriding control inputs because HAL(A) knows best, while HAL(B) will warn pilots and make difficult what it considers as "incorrect" control inputs it will always allow the pilot to stuff it up if they really want because the pilot knows best.

The hissy-fit system HAL(MAX) seems to me to overturn the old B philosophy and head much more towards A, but worse, it decides it knows best (where best is mistrim AND to the stops at high speed and low alt) based on a single AOA sensor rather than the multiply redundant sensor sets of HAL(A) (or B).

That to me is the really sad thing - Boeing knows (or knew) how to do this stuff properly, but for some reason they decided not to for MAX. It's not just doing FBW properly 777-style, it's MCAS itself - it's looking like they ripped MCAS straight off the KC-46, except that there it uses 2 AOA inputs, so at some point in copying the system they reduced the number of AOA inputs to the MCAS system. Why on earth would anyone do that?
infrequentflyer789 is offline  
Old 30th Apr 2019, 21:34
  #4654 (permalink)  
 
Join Date: Apr 2019
Location: USA
Posts: 217
Originally Posted by weemonkey View Post
No, just show us the evidence.
Please define what you mean by "evidence."

BTW, does that definition also apply to all the other players in the chain of causation, or just the aircrew?
737 Driver is offline  
Old 30th Apr 2019, 21:47
  #4655 (permalink)  
 
Join Date: Jun 2009
Location: florida
Age: 77
Posts: 1,128
Salute!
From Bill
If I understand correctly MCAS is a sub-system designsd solely to counteract the lift generated by the engine nacelles at higher than normal AOT........
=======
Why did they not simply alter the elevator feel circuit so that higher force was required to pull back on the stick, sorry column if the AOT was too high and the stick forces were reducing due to the nacelle lift
The problem, Bill, et al, is that the plane required an aerodynamic fix for pitch moments approaching the stall AoA. Sure, in noirmal, non-FBW systems you would expect increasing back force to increase AoA. The new motor mount and such resulted in less back force per each increase in AoA - aero force, not the artificial feel sustem they already had. A pure cable system with no "help" would have made that very obvious for most of us here, especially those with lottsa light plane time. So Boeing figured they would just crank the stab to generate more nose down pitch moment, and the existing feel and such would take care of everything else, huh?
.
- Make the sucker nose heavy and use a single AoA vane to trigger it. Don't sweat a FUBAR vane, as the stick shaker would prolly be going off and provide a clue that something wasn't right
- Let her rip for almost ten seconds and 2.x units nose down, then wait 5 seconds and do it again.
- Don't look at airspeed, just flaps and autopilot settings besides the AoA vane
- To disable the doofer, simply turn off all the electric trim to the stab. Neat, huh? Oh, you lose the yoke trim Gums! No biggie, we can crank that little wheel 50 times. Just don't get fast.
- Yeah that's it. And let's increase the authority of MCAS a bit to be on the "safe" side and don't advertise this, as it might require a sim ride or something.
================
And finally today's comment: @ driver. The first crew call I can see about AoA vane is about 4 minutes from WoW. It could be that at that point they turned the electric trim back on.. at 43:11 we see manual trim from yoke, and sure enuf, 5 seconds later we see MCAS crank the trim down to 1.0 from 2.3 units and they were doomed.

Gums sends...
gums is online now  
Old 30th Apr 2019, 21:48
  #4656 (permalink)  
 
Join Date: Apr 2009
Location: Hotel Gypsy
Posts: 2,830
infrequentflyer789

Far more eloquently presented than my effort. I wholeheartedly agree.
Cows getting bigger is offline  
Old 30th Apr 2019, 22:04
  #4657 (permalink)  
 
Join Date: May 2010
Location: Boston
Age: 68
Posts: 439
Originally Posted by weemonkey
No, just show us the evidence.
Please define what you mean by "evidence."
Originally Posted by 737 Driver View Post
Please define what you mean by "evidence."

BTW, does that definition also apply to all the other players in the chain of causation, or just the aircrew?
At this point (for either accident) "evidence" in a formal sense is not available to the general public.

What is available are a precious few facts and (sometimes strongly held) opinions and theories based on individuals backgrounds.

While some (my self included) may disagree with 737 drivers analysis on some points he has presented detailed explanations and insight that clearly provide an experienced pilots view of things.

In that context it would be equally (not) usefull to say "show me the evidence it was -not- primarily pilot error".

If you have not read his longer posts they are well worth reading, even if you do not end up agreeing with all the points.





MurphyWasRight is offline  
Old 30th Apr 2019, 22:07
  #4658 (permalink)  
 
Join Date: Apr 2019
Location: USA
Posts: 217
Originally Posted by gums View Post
And finally today's comment: @ driver. The first crew call I can see about AoA vane is about 4 minutes from WoW.

Gums sends...
From the preliminary accident report:
At 05:38:44, shortly after liftoff, the left and right recorded AOA values deviated. Left AOA decreased to 11.1° then increased to 35.7° while value of right AOA indicated 14.94°. Then after, the left AOA value reached 74.5° in 3⁄4 seconds while the right AOA reached a maximum value of 15.3°. At this time, the left stick shaker activated and remained active until near the end of the recording. Also, the airspeed, altitude and flight director pitch bar values from the left side noted deviating from the corresponding right side values. The left side values were lower than the right side values until near the end of the recording.

At 05:38:43 and about 50 ft radio altitude, the flight director roll mode changed to LNAV.

At 05:38:46 and about 200 ft radio altitude, the Master Caution parameter changed state. The First Officer called out Master Caution Anti-Ice on CVR. Four seconds later, the recorded Left AOA Heat parameter changed state.

<snip>

At 05:42:51, the First-Officer mentioned Master Caution Anti-Ice. The Master Caution is recorded on DFDR.

At 05:42:54, both pilots called out “left alpha vane”.


​​​​​​
From the data provided, it appears that the Left Alpha Vane warning was triggered within 10 seconds after liftoff. The First Officer called out "Master Caution, Anti-Ice" as would have been procedure. Normally, that call should have been followed up with a verbalization of what particular malfunction triggered the Master Caution light. The crew did not actually get around to doing this until a little more than four minutes after the light first illuminated.

Further examination of the DFDR output indicates that the first Master Caution alert was reset. This is normal procedure to allow for additional alerts, but it also extinguished the "Anti-Ice" annunciator. It appears that the crew simply forgot to look for the actual malfunction annunciated on the overhead panel. For reasons, that are not entirely clear from the data, the Master Caution light came on again at around the 5:42:50 mark, re-illuminating the "Anti-Ice" annunciator. The Master Caution light was reset again. It is at this point, four minutes after the original alert, that the pilots looked up and confirmed the "L ALPHA VANE" annunciation.

737 Driver sends.....

Last edited by 737 Driver; 30th Apr 2019 at 22:43. Reason: added comment
737 Driver is offline  
Old 30th Apr 2019, 22:16
  #4659 (permalink)  
 
Join Date: Nov 2006
Location: Scotland
Posts: 52
737Driver and his cohorts seem intent on diverting attention towards alleged deficiencies in the airmanship of the crews of the two 737 max aircaft that crashed rather than dealing with the real villains of the piece, namely, the FAA and Boeing. I hope that EASA and other foreign regulators hold the FAA's and Boeing's feet to the fire and refuse to lift their grounding of the MAX until a proper SAFE fix has been implemented.

MCAS needs to be removed completely from the 737 Max as it is a far too powerful and dangerous solution to the issue of stick force gradient at high angles of attack. EASA et al should demand that a stick-pusher system should be provided to meet the certification requirements, or else the MAX will not fly passengers in Europe.

Personally, I hold the FAA most culpable for the crashes that have occurred due to MCAS. Whilst aircraft manufacturers such as Boeing, or Airbus, may be tempted to cut corners in pursuit of profit, the regulators are supposed to prevent unsafe commercial aircraft from receiving certification.
Avionista is offline  
Old 30th Apr 2019, 22:43
  #4660 (permalink)  
 
Join Date: Dec 2014
Location: USA
Posts: 34
Originally Posted by rodlittle View Post
Does anyone on this topic know about Boeings system design ? and if so can they please explain to this simple pilot why mcas was designed in the waay it was, If I understand correctly MCAS is a sub-system designsd solely to counteract the lift generated by the engine nacelles at higher than normal AOT. It does this by trimming the stab nose down meaning that if the MCAS system fails due to incorrect AOA info, unless corrected by the PF its heading for disaster.
Why did they not simply alter the elevator feel circuit so that higher force was required to pull back on the stick, sorry column if the AOT was too high and the stick forces were reducing due to the nacelle lift
This could surely have been done so that forward ie nose down column movement was not affected.
This would mean that what ever happened the aircraft would not be left with a nose down trim and would not therefore be trying to fly into the ground.
This was discussed somewhere in the thousands of preceding posts. I think we've reached the point (probably long past it really) where there's nothing more to really be said until new information is released from the investigating authorities.

Basically (if I recall correctly) the elevator feel doesn't operate in a continuously variable fashion relative to AoA. Also the elevator feel system does not have enough authority to maintain the linear stick force called for by certification reqirements. Finally, EFS operates during the stall, stick shaker active, etc. while MCAS (or its effect on stick feel) is needed prior to the stall.

ams6110 is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.