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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 11th Mar 2019, 19:43
  #421 (permalink)  
 
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Originally Posted by aflyer100 View Post
In ground school, I was taught to think that toward the windscreen was on. That provides an alternative to thinking up/down and (at least for me) makes it feel consistent for both the panel and overhead switches. I suppose this might not feel natural to all.
come on, these are guarded switches, not the usual switches for everyday use.
on a guarded switch the switch movement is the same as the guard movement. It is very natural.
The stabtrim cutout switches are no cause for concern.
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Old 11th Mar 2019, 19:46
  #422 (permalink)  
 
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Originally Posted by Raptor Systems TT View Post
If those reports are half accurate,severe big bird strikes rendering engines and some control surfaces inoperable coupled with a relatively inexperienced crew not being able to manage the sudden crisis ?

**This comment is an assessment based solely on assuming the eyewitness reports were accurate.













The evidence from the crash site clearly indicated a very high energy impact that can only have been created by an impact very substantially in excess of terminal velocity. This in turn indicates that the engines must have been running with high output, which is inconsistent with a bird strike. Damage to control surfaces to the extent required to make the airframe unflyable is also inconsistent with any possible bird strike.

As you say, eyewitnesses can be unreliable.
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Old 11th Mar 2019, 19:47
  #423 (permalink)  
 
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could it just be a fault with the AOA sensors feeding duff information and causing the Dive?

Then depending on when cpt did his conversion he just got overloaded.
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Old 11th Mar 2019, 19:47
  #424 (permalink)  
 
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Originally Posted by cncpc View Post
My understanding is that MCAS is only operative with the AP off and flaps extended? Just putting the question out for clarification.
​​​​​​MCAS activates automatically when all of the following conditions are met:
High angle of attack
Autopilot disengaged
Flaps are up
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Old 11th Mar 2019, 19:50
  #425 (permalink)  
 
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According to the Reuters report 4 witnesses were specific to sound which is historically much more accurate and telling than sight. Not with regard to specifics but abnormality. It's common for individuals to do a "double take" specific to visual clues since you tend to need to
process and double check an anomaly but we respond much more decisively to aural clues.
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Old 11th Mar 2019, 19:53
  #426 (permalink)  
 
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I'm not surprised by the Chinese reaction. The US government is currently almost at war with Huawei who not only make phones, but in a far larger scale a lot of the technology used by Mobile Operators at base stations and in their data centres. The US has had their CFO arrested in Canada, and is trying to extradite her to the US, and leaning hard on their allies to restrict use of their technology.

The opportunity to put restrictions in a semi-legitimate and public way against a major US company I am sure did not pass the Chinese government by.
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Old 11th Mar 2019, 19:54
  #427 (permalink)  
 
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Originally Posted by cncpc View Post
My understanding is that MCAS is only operative with the AP off and flaps extended? Just putting the question out for clarification.
This page seems to have a good overview of the MCAS:

737 MAX - MCAS

Someone said it becomes active at 1000 feet AGL, not sure if this a player if you're trying to climb above 1000 with MCAS and/or AOA problems.
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Old 11th Mar 2019, 19:55
  #428 (permalink)  
 
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Thumbs up

Originally Posted by EDLB View Post


snip ........... snip
We most likely know now with 20/20 hindsight, that the AD was not a sufficient reaction to prevent further fatalities.


a point to ponder far better than many of the last 24 hrs of posts.
If one assumes it is a known problem (LionAir type) then what part of the AD is not sufficient?

Is it the technical part or the compliance part?

When all is said and done we need to understand this question in order to un-ground fleets

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Old 11th Mar 2019, 20:00
  #429 (permalink)  
 
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Originally Posted by CONSO View Post
Unfortunately- Boeing will most likely keep it proprietary such that perhaps- maybe- it will be an exhibit in one or more of the coming- existing lawsuits- even then it may well be supplied under a protective order and available in context only to the jury IF pressed. Otherwise a summary of standard procedure of xyz group checked by abc group and signed off by ccc senior manager. Ditto for FAA and other agencies. And having been determined to meet section - 75635-cvr-67.1834 of code fubar321.45 as amended was within the rules ..

The noise you hear is A** covers slamming closed...
LOL yes that FUBAR321.45 regulation is so hard to overcome!

Seriously I would welcome a Congressional hearing and make Boeing show itís laundry and have the arse-coverers toss each other under the bus. When your proprietary code starts killing people it needs to be examined.
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Old 11th Mar 2019, 20:00
  #430 (permalink)  
 
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Originally Posted by SLFinAZ View Post
According to the Reuters report 4 witnesses were specific to sound which is historically much more accurate and telling than sight. Not with regard to specifics but abnormality. It's common for individuals to do a "double take" specific to visual clues since you tend to need to
process and double check an anomaly but we respond much more decisively to aural clues.
If I've learned anything in life, it's not to jump to conclusions, least of all based on eyewitnesses. The CVR and FDR should answer most of the questions. Mine you I still can think of no good reason why with the technology now available internal and external video recording is not also captured on all new airframes.
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Old 11th Mar 2019, 20:01
  #431 (permalink)  
 
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Originally Posted by extreme P View Post
​​​​​
High angle of attack
Autopilot disengaged
Flaps are up
The kicker being, if I recall the LionAir mishap discussion, the AP disengages when the AoA goes pear shaped (or rather, the AoA signal to the system).
That linkage informs my understanding of the fix that Southwest went for.

(As I recall, we beat to death in various AF447 discussions (all now in the Tech Log forum) whether or not having an AoA gage for the pilots to refer to was a good idea or not. SW, it seems, has decided that it's a good idea at this point in time.

Last edited by Lonewolf_50; 11th Mar 2019 at 20:12.
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Old 11th Mar 2019, 20:04
  #432 (permalink)  
 
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Engineer here

1. Since those knobs to shutdown the mcas are same as sts breaker then sts trim will also turned off. While sts is more frequent needed for landing/takeoff. Right?

2.in normal flight/aoa vane is ok, it's hard to differentiate when mcas is working? Only different while flaps already up right, or deliberately automated pilot off while getting High angle pitch. Only just 5s trimming that iterates? It will ran rare right in stall regime right, or also running on the sharp banking?

3. Its not possible to turned off just mcas instead whole sts trim system?

4. Eth302 is the b37m with aoa sensor indicator like US airlines has or cheaper that doesn't have aoa sensor indicator like lion air has.




Last edited by Realbabilu; 11th Mar 2019 at 20:21.
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Old 11th Mar 2019, 20:12
  #433 (permalink)  
 
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There are thousands of airlines operating millions of flights annually, many with substantial aircraft. And if what is written here is to be believed, many of these are lacking standards, training and ability. Is it just by the grace of God that we don't have planes dropping out of the sky daily? Or the beauty of technology?
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Old 11th Mar 2019, 20:16
  #434 (permalink)  
 
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Originally Posted by 42... View Post
Not certified to stall? Hogwash, we just did full stall recoveries in the sim. Extreme buffet, wingrocking, 6000 plus vvi sinking stalls. This however was not a MAX sim.
Keep in mind that sims have very little fidelity in reproducing a actual fully stalled condition.
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Old 11th Mar 2019, 20:16
  #435 (permalink)  
 
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Is it just by the grace of God that we don't have planes dropping out of the sky daily? Or the beauty of technology?
Yes.
Squinty, let's not undersell the hard lessons learned in the industry, over decades, that are procedural in nature and which include CRM and training, etc.
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Old 11th Mar 2019, 20:21
  #436 (permalink)  
 
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Originally Posted by golfyankeesierra View Post


come on, these are guarded switches, not the usual switches for everyday use.
on a guarded switch the switch movement is the same as the guard movement. It is very natural.
The stabtrim cutout switches are no cause for concern.
Thanks to you and airbubba ,,, that clarifies that aspect.

My house was built for a guy who had lived in GCM: the light switches are all over the place!! Some up, some down, multi-gang defying logic, it’s taken me nearly 15 years to get my head round which does what and how. And inverting a multi-gang dual connection doesn’t resolve things!
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Old 11th Mar 2019, 20:22
  #437 (permalink)  
 
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Originally Posted by golfyankeesierra View Post


come on, these are guarded switches, not the usual switches for everyday use.
on a guarded switch the switch movement is the same as the guard movement. It is very natural.
The stabtrim cutout switches are no cause for concern.
Ever tried to switch on the emergency exit lights on a 737?
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Old 11th Mar 2019, 20:29
  #438 (permalink)  
 
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Originally Posted by Vessbot View Post
Yes. The scheme is, on any vertical surface (like the instrument panel, or a wall) up = on, same as any switch in the rest of the world. On any horizontal surface (center pedestal, or overhead) forward = on. For the center pedestal, the forward = on scheme elegantly matches what you're used to (toward the top of your eyeball = on). But I've always thought that that's a stupid application on the overhead, which gives the feeling of upside down switches since it reverses the "toward the top/bottom of your eyeball" relationship, and instead it should just be treated like a wall.

And the 737 seems to have very few switches in places that aren't the overhead, so the overhead upside-down scheme prevails. But the stab cut out switches are on a place where the normal (up = on) scheme is in place.
Ahh typical American. North America and aviation are about the only places where UP is on for a switch. Most other places in the world down is on.
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Old 11th Mar 2019, 20:29
  #439 (permalink)  
 
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Originally Posted by Realbabilu View Post
Engineer here

1. Since those knobs to shutdown the mcas are same as sts breaker then sts trim will also turned off. While sts is more frequent needed for landing/takeoff. Right?

2.in normal flight/aoa vane is ok, it's hard to differentiate when mcas is working? Only different while flaps already up right, or deliberately automated pilot off while getting High angle pitch. Only just 5s trimming that iterates? It will ran rare right in stall regime right, or also running on the sharp banking?

3. Its not possible to turned off just mcas instead whole sts trim system?

4. Eth302 is the b37m with aoa sensor indicator like US airlines has or cheaper that doesn't have aoa sensor indicator like lion air has.



The STS system trims for speed, and works against the pilot when it operates. It is not a system that helps the pilots to keep the aircraft in trim. You would not notice if it was disabled. Itís an annoying piece of kit and only installed for certification reasons.
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Old 11th Mar 2019, 20:31
  #440 (permalink)  
 
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What I find interesting, is whenever MCAS is being discussed (re the Lion Air crash and possibly this one as more data comes to light), there are a lot of posts saying that if they’d just done the trim runaway checklist, everything would have been OK. Yes, probably. But what would have led them to that checklist? If you took off in a 737 MAX on a flight where nothing went wrong and you didn’t crash (rare, I know ) and manually flew the cleanup, would you get a bit of trim from MCAS as the last of the flap went in, making it something “normal” and “expected"?

If you had read all the manuals, then got a stall warning shortly after clean, you’d expect the MCAS to do a bit of trimming, yes? So “normal” behaviour? It’s also intermittent and you can trim back and forth yourself, so hardly a “runaway” in the traditional sense; in fact not in the sense of the QRH either, which describes a runaway stab as “continuous”.

So, unless you are prepared to do the runaway stabiliser drill every time you see the trim wheel moving and it wasn’t initiated by you (which would lead to lots of very short flights), how do you tell in a limited timeframe whether MCAS is trying to save your life or trying to kill you...?
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