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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 8th Apr 2019, 07:11
  #3581 (permalink)  
 
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Not trying to criticise the crew but rather clarify my reading of the data presented:

1. Pilot manually flying, gets an AoA disagreement on climb out, pilots clean up.
2. Pulls back on stick and gets a stick shaker.
3. Pilot trims logically, MCAS trims ND worried about AoA.
4. At some point AP goes in then out, not clear why.
5. MCAS trims ND.
6. Pilots cut-out trim. (It seem MCAS tries to trim down to no effect which was good)
7. No further trim inputs from pilots (Looks like trim wheel not used)
8. Issues with stick forces, re-engage automatic trim and lose control.
9. Manual trim wheel doesn't seem to have been used
9.Throughout speed is increasing because thrust has not changed so stick forces are increasing.

A confusing situation no doubt, but after cutting out the electric trim would setting a sensible pitch and reducing power while using the trim wheel have lead to a different result?
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Old 8th Apr 2019, 07:42
  #3582 (permalink)  
 
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Schnowzer,
AoA Disagree not fitted to the accident aircraft.
Stick-shake after wt-off-wheels, normal operation of stall warning system with (erroneous) high AoA.
MCAS only active with flap up; nose down trim MCAS operation as designed - until it isn’t. **
Pilots continuing concern about stick-shake and corresponding, but erroneous indications of low speed / stall awareness on EFIS (no immediate indication / association with AoA).
Some texts indicate that MCAS is inoperative with AP engaged.
MCAS intermittently trims down, but at a rate / time ratio which overcomes pilots opposing trim.
Pilot electric trim increasingly ineffective (nose up), MCAS more effective nose down due to tail forces / hinge moments.
Stab off, manual wheel trim similarly unable to move trim nose up due to high forces.
A point is reached where what ever option, SOP, etc, is applied, then if the aircraft is not within reasonable control (trim) - manageable by one pilot, there is little more that can be done.

** Underlying question applying to many posts - ‘how do pilots know when the MCAS is not working as required ?’
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Old 8th Apr 2019, 07:48
  #3583 (permalink)  
 
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When they went thru checklist Auto throttle 'deselect' not done.

Power left at 94% until end.

In cold light of day Lawyers will have a field day with this.
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Old 8th Apr 2019, 08:39
  #3584 (permalink)  
 
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A couple quick questions for the airline pilots out there. Iím trying to get a general feeling for the experience/airmanship level of my colleagues around the world. For any transport category jet, how many of you would:
  1. Engage an autopilot with a stick shaker active or any other signs of unreliable airspeed on departure?
  2. Retract flaps with a stick shaker active or any other signs of unreliable airspeed on departure?
  3. Be uncomfortable manually controlling thrust at any point during the flight.
  4. Be uncomfortable manually flying the aircraft during an emergency?
  5. Distrust the average pilot in your company to accurately fly manually during an emergency.
  6. Not use the electric trim system to relieve control column pressure (if it is having a positive effect, such as was almost assuredly the case in the Lion-air and Ethiopian accidents)?
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Old 8th Apr 2019, 08:54
  #3585 (permalink)  
 
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Originally Posted by CodyBlade View Post
When they went thru checklist Auto throttle 'deselect' not done.

Power left at 94% until end.

In cold light of day Lawyers will have a field day with this.
Of course that’ll be the job of Boeing lawyers to mitigate and try to reduce liability but ultimately the main culprit will come down to MCAS, it’s design, certification, discreet implementation, lack of redundancy and ultimately its power to overcome pilot actions without crews being made fully aware of its capabilities.

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Old 8th Apr 2019, 08:54
  #3586 (permalink)  
 
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Originally Posted by CodyBlade View Post
When they went thru checklist Auto throttle 'deselect' not done.

Power left at 94% until end.

In cold light of day Lawyers will have a field day with this.
Well, if we want to get really picky, did they complete the "Approach to Stall or Stall Recovery" Non-Normal Manoeuvre (NNM) first, because that the second line says"
"Immediately do the following at the first indication of stall (buffet or stick shaker).
The third item is (step 2 disconnect autothrottle):
"smoothly apply node down elevator to reduce the angle of attack until until buffet or stick shaker stops".

Glad they skipped that NNM and went onto something else. I wonder what the lawyers will make of that decision?

In the cold hard light of day, 3 crews were placed in situations beyond the engineering assumptions of all the SOP's, NNC and NNM's. They faced a continuous cacophony of noise (stick shaker), that has been shown by anecdotal reports in this thread to induce tunnel vision and difficulty doing ANY task, including just flying the aircraft. Two crew were unable to cope, the third had assistance from an additional pilot.

Perhaps as the lawyers are debating and dissecting second by second details, they should do it with the continuous Stick Shaker loop in the background. It really is an asymmetric situation for the crews, if they don't do something (following the NNM for the stick shake and shove the nose down) and save the day at that point they get no credit, yet they don't do something else everyone wants to point to them and say see, pilot error. For the manufacturer it is a business decision to hang the crew if possible as it reduces their liability. They get to cherry pick the inevitable forced pilot errors in such difficult circumstances and gloss over the manufacturers errors and omissions. Nothing personal, just business to make the most bucks it can.

I've pretty much argued consistently in the Lion Air thread and this one, that the crews were put into incredibly difficult circumstances by the rational design choices of the manufacturer. Those design choices were made under circumstances of far less pressure than the crews faced. The only possible justification Boeing could make is was more profitable for them to design the system this way.
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Old 8th Apr 2019, 08:59
  #3587 (permalink)  
 
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DHC6tropics, #3633
Without context none of these ‘predetermined’ measures can rate airmanship.
Experience might be judged according to what has been done (past), but this cannot be reliable projected for the use, the application of that experience in some future event. Who judges, you or an external observer.
Airmanship is not a quantity, at best it’s a rating, a term, something which can be used in conversation because it impossible to deal with these qualities in any other way.

Context, hindsight, and the human condition.
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Old 8th Apr 2019, 09:12
  #3588 (permalink)  
 
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Originally Posted by KyleRB View Post


Of course thatíll be the job of Boeing lawyers to mitigate and try to reduce liability but ultimately the main culprit will come down to MCAS, itís design, certification, discreet implementation, lack of redundancy and ultimately its power to overcome pilot actions without crews being made fully aware of its capabilities.

going to be judged not by your peers or professionals who can intepret the data objectively.But by mom and pop.
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Old 8th Apr 2019, 09:18
  #3589 (permalink)  
 
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Originally Posted by alf5071h View Post
DHC6tropics, #3633
Without context none of these Ďpredeterminedí measures can rate airmanship.
Experience might be judged according to what has been done (past), but this cannot be reliable projected for the use, the application of that experience in some future event. Who judges, you or an external observer.
Airmanship is not a quantity, at best itís a rating, a term, something which can be used in conversation because it impossible to deal with these qualities in any other way.

Context, hindsight, and the human condition.
Are you serious!?! The ability to make fundamental decisions with regards to configuration and automation in abnormal situations and the ability to confidently and accurately manually fly the aircraft are pillars of airmanship. Unfortunately, airmanship can not be taught purely in a classroom. Much of airmanship comes from professional experience. Iím not American, but I applaud them for their 1500 hour rule. Learning the fundamentals of flying and airmanship should happen long before a pilot is allowed to set foot in a transport category jet.
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Old 8th Apr 2019, 09:19
  #3590 (permalink)  
 
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ET standard pax weight

Hi, anyone knows the standard pax weight used by Ethiopia Airline? Male/Female. The ECAA gives a standard weight 90 M/ 70F including 20lbs handbag. Is it the same?
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Old 8th Apr 2019, 09:25
  #3591 (permalink)  
 
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Originally Posted by CodyBlade View Post
When they went thru checklist Auto throttle 'deselect' not done.

Power left at 94% until end.

In cold light of day Lawyers will have a field day with this.
Getting a bit fed up with this canard. Not saying it shouldn't have been done, but what exactly would this have done to the throttle position in the accident scenario?
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Old 8th Apr 2019, 09:31
  #3592 (permalink)  
 
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Originally Posted by fizz57 View Post
Getting a bit fed up with this canard. Not saying it shouldn't have been done, but what exactly would this have done to the throttle position in the accident scenario?
Ummm...it would have allowed them to manually control the thrust levers...which is exactly what basic airmanship would dictate.
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Old 8th Apr 2019, 09:38
  #3593 (permalink)  
 
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Fight the normalization of the abnormal

I see more and more posts selecting solutions which are strictly inside the coordinates of what we "know" it is possible. (EG: more training, software patch...) and not seriously mentioning much better / obvious ones.

I say: listen to people from other industries. What we sometimes believe impossible in terms of complexity / cost / time may not be so.

It's time to roll up our sleeves and produce good computer systems for planes. Systems in which sensor signals jumping straight up to off - the - scale - high are automatically rejected and have zero impact. For a start. Updating whichever rules as we go to keep a cheap but much safer solution.

We totally know how to do it right, it's just we forbid ourselves to do it by all sorts of rules and bureaucracy. Let's not accept another band aid.

Somebody wrote many pages ago he spent 30 years in the industry and failed to change substandard quality. Sorry I forgot who. But to him and everyone else, we have to keep fighting, as futile as it may be. It's simply what we have to do.
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Old 8th Apr 2019, 09:56
  #3594 (permalink)  
 
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Originally Posted by fizz57 View Post
Getting a bit fed up with this canard. Not saying it shouldn't have been done, but what exactly would this have done to the throttle position in the accident scenario?
You miss my point.
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Old 8th Apr 2019, 09:56
  #3595 (permalink)  
 
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Originally Posted by ecto1 View Post
It's time to roll up our sleeves and produce good computer systems for planes. Systems in which sensor signals jumping straight up to off - the - scale - high are automatically rejected and have zero impact. For a start. Updating whichever rules as we go to keep a cheap but much safer solution.
In general, the industry does, and overall does a very good job of it. Input value filtering is normal, and even the A330 that nose-dived in cruise had computers which did. It was done inappropriately, but most of the time the erroneous values were rejected.

The problem here lies much earlier, in specifying the requirements for MCAS. More specifically, the failure modes and the severity and likelihood of each were not properly analysed.

We totally know how to do it right, it's just we forbid ourselves to do it by all sorts of rules and bureaucracy. Let's not accept another band aid.
Au contraire. Aviation is the industry which mandates appropriate techniques. They are well-known, and used.

Add-on systems that bring airliners back into compliance, which are not by themselves aerodynamically completely compliant to regulations, are literally as old as jet airliners themselves. Many types have stick-nudgers or stick-pushers, and they work fine, and are perfectly sensible to use. But that does not mean one can skip due diligence in developing them, which includes a thorough risk and hazard assessment.

Bernd
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Old 8th Apr 2019, 10:02
  #3596 (permalink)  
 
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Originally Posted by KyleRB View Post
Of course thatíll be the job of Boeing lawyers to mitigate and try to reduce liability but ultimately the main culprit will come down to MCAS, itís design, certification, discreet implementation, lack of redundancy and ultimately its power to overcome pilot actions without crews being made fully aware of its capabilities.
CurtainTwitcher
Perhaps as the lawyers are debating and dissecting second by second details, they should do it with the continuous Stick Shaker loop in the background. It really is an asymmetric situation for the crews, if they don't do something (following the NNM for the stick shake and shove the nose down) and save the day at that point they get no credit, yet they don't do something else everyone wants to point to them and say see, pilot error. For the manufacturer it is a business decision to hang the crew if possible as it reduces their liability. They get to cherry pick the inevitable forced pilot errors in such difficult circumstances and gloss over the manufacturers errors and omissions.
Originally Posted by CodyBlade View Post
going to be judged not by your peers or professionals who can intepret the data objectively.But by mom and pop.
Not a lawyer. Presumably there are differing degrees/amounts of liability. More important are punitive damages, which can be many multiples of the actual damages claimed. All of these will be argued intensely, and the various role players will have differing inputs into this process, other than the dead pilots.
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Old 8th Apr 2019, 10:13
  #3597 (permalink)  
 
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Before rotation there is speed where AoA sensors should work in the intended way, why not check the values then and throw out the bad one. That does not help for events after rotation but would atleast check for ground damage.
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Old 8th Apr 2019, 11:03
  #3598 (permalink)  
 
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Hello all,

My understanding from these situations is one contributing factor may be that a pilot may ultimately get into a situation where he or she has little to no ability to correct a badly out of trim Max manually or electrically due to aerodynamic loads in certain flight situations. What I have not seen is anyone noting is if this inability, irregardless of how it came about, is the same in other aircraft from Boeing or Airbus. From a 320 to a 380 or a 737 NG or 747 to a 787 would a pilot have the ability to re-trim from the same situation these two flights faced?

TME
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Old 8th Apr 2019, 11:34
  #3599 (permalink)  
 
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Originally Posted by TeachMe View Post
My understanding from these situations is one contributing factor may be that a pilot may ultimately get into a situation where he or she has little to no ability to correct a badly out of trim Max manually or electrically due to aerodynamic loads in certain flight situations.
That appears to be true for manual (wheel) trim, but there's no evidence that it's the case for electric trim.

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Old 8th Apr 2019, 11:41
  #3600 (permalink)  
 
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Originally Posted by ecto1 View Post
I see more and more posts selecting solutions which are strictly inside the coordinates of what we "know" it is possible. (EG: more training, software patch...) and not seriously mentioning much better / obvious ones.

I say: listen to people from other industries. What we sometimes believe impossible in terms of complexity / cost / time may not be so.

It's time to roll up our sleeves and produce good computer systems for planes. Systems in which sensor signals jumping straight up to off - the - scale - high are automatically rejected and have zero impact. For a start. Updating whichever rules as we go to keep a cheap but much safer solution.

We totally know how to do it right, it's just we forbid ourselves to do it by all sorts of rules and bureaucracy. Let's not accept another band aid.

Somebody wrote many pages ago he spent 30 years in the industry and failed to change substandard quality. Sorry I forgot who. But to him and everyone else, we have to keep fighting, as futile as it may be. It's simply what we have to do.
Or we could get rid of the grandfathering loophole that Boeing and the FAA have abused, where software has been used as a bandaid. A320/ B787 etc that were designed to make full use of computer systems from the ground up are fine. It is the unholy mixing of digital & analogue on the MAX that is the issue.

Would a similar AOA failure on an NG cause a crash? Almost certainly not.

In my opinion, Boeing & FAA have stretched the definition of a derivative aircraft beyond what is reasonable. What will be interesting will be impact on 777X, I am guessing FAA will be reviewing all assumptions on that now, and we might even see the end of "NG" derivative programmes (as opposed to stretches) with authorities insisting that if you build a new plane, it meets current standards. This is how it works in contruction. Sure, you don't have to rebuild a 40 year old building to new standards, but you can't say "this design met earthquake standards in 1990, so I can just build a derivative of it"





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