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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 12th Mar 2019, 00:21
  #541 (permalink)  
 
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Originally Posted by oldoberon View Post
Can someone clear up something for me please.

I know from reading the whole thread the MCAS has a single AoA input, but some post refer to xchecking against the 2nd AoA ( which is not connected to MCAS)

However post 188 says this

post 188

At least Southwest took it's own initiative by adding an extra AOA indicator into 737 MAX for crew to cross-check erroneous data, but, shouldn't that be a Boeing responsibility and hence fitted to the worldwide fleet? I doubt Ethiopian purchased or insisted on these upgrades.

Is this extra a 3rd AoA or is there only 1 AoA and this IS the 2nd "comparison only" one.

Just to add I was horrified to read the certification is basically a grandfather one, when major changes to airframe, engine or flying controls are made it should be a new certification, loved the analogy " like putting a new dash and a 300bhp engine in a model T and saying it is safe to use!

ta

Oldoberon

AFAIK there are 2 AOA-s on the 737, the MCAS uses only AOA-1, Southwest elected the option of having AOA-1 on the PIC EFIS & AOA-2 on FO EFIS. please correct me if I am wrong.
Also if you want to see "grandfathered", compare the DC-9 cockpit with the B717. Same type rating, one day differences class is all that is required to go from one to the other.....
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Old 12th Mar 2019, 00:23
  #542 (permalink)  
 
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Originally Posted by savall View Post
They opted to have an additional sensor added as backup verification. A feature which I believe should have been installed as standard.
I don't think so. There is 2 AOAs installed on every MAX, SWA bought the option to have the AOA info displayed to the pilots on their respective instruments, not just the AOA disagree light.
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Old 12th Mar 2019, 00:26
  #543 (permalink)  
 
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Originally Posted by hans brinker View Post
I don't think so. There is 2 AOAs installed on every MAX, SWA bought the option to have the AOA info displayed to the pilots on their respective instruments, not just the AOA disagree light.
Thanks for the correction. I am not familiar with the type, I misinterpreted an earlier post. I still believe having two readouts would have been a sound decision from the beginning.
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Old 12th Mar 2019, 00:26
  #544 (permalink)  
 
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Clear notification that MCAS activated?

I'm a (non-aero) engineer who has done User Interface work in the past. All of the discussions of MCAS seem to suggest you'll only know it's active when the nose pitches down (et al.) without being commanded.

Is there no definitive visual or auditory signal that MCAS is active?
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Old 12th Mar 2019, 00:27
  #545 (permalink)  
 
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Hans

"AFAIK there are 2 AOA-s on the 737, the MCAS uses only AOA-1, Southwest elected the option of having AOA-1 on the PIC EFIS & AOA-2 on FO EFIS."

I am ex ground crew don't know all your abbreviations but you seem to be saying there were always 2 they just reconfigured their functionality.NOT added another as post 188 stated, what is the resulting effect of their change

oldoberon
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Old 12th Mar 2019, 00:35
  #546 (permalink)  
 
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FAA says Boeing 737 Max 8 is airworthy http://www.bbc.co.uk/news/world-africa-47533052

This may well come back to bite them!
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Old 12th Mar 2019, 00:36
  #547 (permalink)  
 
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Originally Posted by henra View Post
Have you looked at least to the most crude bits of information on this crash before climbing up the sope box?
Fuel contamination, engine problems => 383kts, Ultra high energy impact. Scrap it.
instrument problems: 383kts (read: no stall) and sunny, nice weather => WTF instrument should cause this??? I don't see a reasonable scenario for this.
bird strike: => why spearing along at 1000ft at ridiculous speeds after being hit by a bird??? That would be exactly opposite of what you would want to do: Higher altitude and low speed. IMHO not really supported from what we know so far.

I would accept flight control problems ( would be extremely worrying though on a just 5 month old aircraft of a new type!), suicide (but why would someone fly for so long at low altitude and high and increasing speed when he wants to commit suicide?), runaway trim (here we go -that is what has been mostly discussed and wehre there is a precedence).

So if I draw a line below your objection I still end up mostly with what is being discussed here (although I agree it is much to early to be sure it was MCAS).
Would I happily board a MAX tomorrow? Not if I could avoid it.
Okay, I can add one: Pilot disabled for some reason, FO unable to fly the plane.
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Old 12th Mar 2019, 00:37
  #548 (permalink)  
 
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Originally Posted by oldoberon View Post
Hans

"AFAIK there are 2 AOA-s on the 737, the MCAS uses only AOA-1, Southwest elected the option of having AOA-1 on the PIC EFIS & AOA-2 on FO EFIS."

I am ex ground crew don't know all your abbreviations but you seem to be saying there were always 2 they just reconfigured their functionality.NOT added another as post 188 stated, what is the resulting effect of their change

oldoberon
Sorry, after 30 years it is hard not to speak in allcaps three letter words, here is the English version:
Every 737 has 2 Angle Of Attack indicators, and an OPTIONAL warning light for a difference in value between the two. SW have paid extra to display the actual AOA value displayed on the respective pilots instruments. The left pilot seas AOA one, the right pilot sees AOA 2 values. These should be the same, and if they are not seeing the value could help in deciding who is right.

Last edited by hans brinker; 12th Mar 2019 at 02:52.
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Old 12th Mar 2019, 00:45
  #549 (permalink)  
 
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Originally Posted by hans brinker View Post
Sorry, after 30 years it is hard not to speak in allcaps three letter words, here is the English version:
Every 737 has 2 Angle Of Attack indicators, and a warning light for a difference in value between the two. SW have paid extra to display the actual AOA value displayed on the respective pilots instruments. The left pilot seas AOA one, the right pilot sees AOA 2 values. These should be the same, and if they are not seeing the value could help in deciding who is right.
Correct, except the AOA disagree warning light is an optional extra on the 737 MAX, so not every 737 has it.

For example the Lion Air 737 MAX didn't have either of those options installed, so it would have been difficult for the crew to determine they had an AOA disagree situation or not.
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Old 12th Mar 2019, 00:51
  #550 (permalink)  
 
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Several more airlines pull the 737 Max after the 2nd crash in Ethiopia.

Royal Air Maroc RAM, and now BA RSA franchise Comair.

whio would make he Comair decision

Oldoberon
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Old 12th Mar 2019, 00:53
  #551 (permalink)  
 
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Originally Posted by hans brinker View Post
AFAIK there are 2 AOA-s on the 737, the MCAS uses only AOA-1
From the Lion Air thread, I believe MCAS cycles between the 2 AOAs between each flight....
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Old 12th Mar 2019, 00:56
  #552 (permalink)  
 
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Originally Posted by hans brinker View Post
Sorry, after 30 years it is hard not to speak in allcaps three letter words, here is the English version:
Every 737 has 2 Angle Of Attack indicators, and a warning light for a difference in value between the two. SW have paid extra to display the actual AOA value displayed on the respective pilots instruments. The left pilot seas AOA one, the right pilot sees AOA 2 values. These should be the same, and if they are not seeing the value could help in deciding who is right.
Decent write-up here. Also says American had opted for the display feature from the get go.

https://theaircurrent.com/aviation-s...737-max-fleet/
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Old 12th Mar 2019, 01:15
  #553 (permalink)  
 
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I havenít flown a plane as PIC since 1994, but Iím pretty systems automation and computer savvy. Reading the above posts I get the feeling that hardly anyone understands how MCAS really works, not even its designers. It reminds me of the financial crisis a decade ago when the so-called professionals ultimately didnít understand what they created.

Pages of debate on both this and the Lion Air threads about how the thing actually behaves should be a big red flag, regardless of the actual cause of these accidents.
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Old 12th Mar 2019, 01:26
  #554 (permalink)  
 
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Not airframer's

Phylosocopter, the diagram is marked with Ostrower's trademark. It's 98.9 percent clear that it is something Jon created to explain somewhat arcane and technical flight control systems to an essentially layman readership (for his publication "The Air Current"). Not carrying water for Jon here but -- Boeing has enough of headaches at the moment, without even a "rumour" that gives forum folks the "EEEKs."

WillowRun 6-3
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Old 12th Mar 2019, 01:27
  #555 (permalink)  
 
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re post 521
11th Mar 2019, 15:33
#521 (permalink)

. . .


Ask the author where he got the data and MIS info on MCAS- re override by pilot
https://theaircurrent.com/author/jonostrower/
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Old 12th Mar 2019, 01:34
  #556 (permalink)  
 
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Originally Posted by thcrozier View Post
Pages of debate on both this and the Lion Air threads about how the thing [MCAS] actually behaves should be a big red flag, regardless of the actual cause of these accidents.
Yes. In the discussions of both crashes, it has been striking that there has been so much confusion and disagreement about the operation of MCAS, much of it on the part of transport-experienced professional aviators. And no matter how much relevant material I've read, or how often I've re-read it, some things still aren't clear. For instance, some descriptions of the "system" (software patch) suggest that it is necessary for the MAX to be in a high bank for it to be activated. That doesn't make sense and it doesn't seem to have been the case in the Lion Air or the ET crashes (if the ET incident was MCAS-related), but it pops up repeatedly in lists and graphics.

Common sense and basic principles of human engineering dictate that a system or application that creates this much uncertainty and confusion, even among experts in a discipline, is begging for redesign.



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Old 12th Mar 2019, 01:43
  #557 (permalink)  
 
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Originally Posted by thcrozier View Post
I get the feeling that hardly anyone understands how MCAS really works,
yep, I sure as hell don't and I'd love to see it explained in a way so that a dimwit like me (LSA pilot) can understand.
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Old 12th Mar 2019, 01:55
  #558 (permalink)  
 
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". . . begging for redesign" [OldnGrounded]

Seems a prudent conclusion - based on present state of actual information and reasonable inferences.
But there's another design redo flopping onto agendas, isn't there? The certification process itself. Maybe the lithium-ion batteries were a vague straw in the wind, albeit not stretching out an older type design as such. Clearly the MCAS situation - even if this accident doesn't turn out to be rooted in MCAS - is a strong indicator. As others have stated here and on Lion Air 610 thread, the process being set-up and administered so that mods can be added, to a basic type that is decades old, with this result, should not be allowed to persist. I won't even try to sketch a new and improved architecture for the FARs and the industry-regulator collaboration arrangement, even if I could, but isn't this work coming into necessity?

WillowRun 6-3
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Old 12th Mar 2019, 01:56
  #559 (permalink)  
 
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Boeing to upgrade software in 737 MAX 8 fleet in 'weeks'
https://www.reuters.com/article/ethi...-idUSL1N20Z01K

Just wow... Begs the question, how long have they known about the issues???
Was the aircraft pushed out too early to "meet schedule" and increase profit?
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Old 12th Mar 2019, 02:03
  #560 (permalink)  
 
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How?


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