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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 10th Mar 2019, 18:53
  #161 (permalink)  
 
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There seems to be in this thread an early fixation on a previously known cause. This flies in the face of the ability of the industry to assimilate previous causes and promulgate corrective actions world wide.

I'm not about to give much credence to anybody suggesting a cause unless equal arguments include previously identified corrective actions being missing
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Old 10th Mar 2019, 19:02
  #162 (permalink)  
 
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Salute!

@Gilles
Correct me if I’m wrong, but in the case of the Lion Air accident, from what I understood, an AOA probe fault caused the MCAS to put a forward trim on the horizontal stabilisor, causing a fault that essentially looked like a runaway trim, a situation that a pilot could have recovered from by treating it like a runwaway trim.
I am willing to bet that most of us think of "runaway trim" as a fairly constant uncommanded trim that we didn't expect. The MCAS trim implementation is maybe ten seconds of nose down unless you use the manual trim switch or wheel, then it "rests" for 5 seconds and tries to kill you again!!! So sympton is like "intermittent trim" or basically FUBAR trim, especially if not briefed on the MCAS implementation and realizing that the stick shaker and stall alarm was telling me to push over, but Hal was overdoing it.
The previous Lion Air crew turned off the trim and until we hear their testimpny, they may not have realized that their own plane had MCAS failure. And looking at their FDR plots, it was classic MCAS. just like flight 610 the next day.

@CONSO The flap retraction altitude/procedure for the 737MAX is not in my memory bank Seems that normal retraction requires a trim change in most planes ( Airbus, Viper, Raptor, maybe 777 excepted), but not flying that type I am not sure. In any case, it's a configuration change and that is not a great time to have uncommanded trim you are not expecting or trained for.

For the "shut up and wait" folks!! This is a "rumor" forum, but if I were flying this type I would sure as hell be reviewing everything I could get my hands on about the systems' operation ofter gear up and establishing a stabilized climb, and talking with other pilots flying the beast.

Gums opines....
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Old 10th Mar 2019, 19:17
  #163 (permalink)  
 
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There seems to be in this thread an early fixation on a previously known cause. This flies in the face of the ability of the industry to assimilate previous causes and promulgate corrective actions world wide.
You would think so but it seems not.
The Flight Radar data fits another MCAS event and not much else.
737s dont just augur in.
Flap retraction can be initiated as low as 400 feet,more commonly 800 feet.
So MCAS event is entirely feasible.
Skipper new to type<-------red flag
Co-pilot 200 hrs<-------red flag
New Skipper rostered with inexperienced co-pilot<------huge red flag
Ethiopian track record<------red flag
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Old 10th Mar 2019, 19:21
  #164 (permalink)  
 
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Originally Posted by lomapaseo View Post
There seems to be in this thread an early fixation on a previously known cause. This flies in the face of the ability of the industry to assimilate previous causes and promulgate corrective actions world wide.

I'm not about to give much credence to anybody suggesting a cause unless equal arguments include previously identified corrective actions being missing
See thread:
Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed
Thus Boeing hasn't implemented any fixes of the MCAS problem yet. While many airlines probably did some additional pilot instruction and other pilots learned of the problem in places like PPRuNe, many other pilots probably didn't.

And of course even if a pilot was informed of something doesn't mean he will remember it in a critical situation.
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Old 10th Mar 2019, 19:30
  #165 (permalink)  
 
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Originally Posted by Rananim View Post
The Flight Radar data fits another MCAS event and not much else.
I will comment on your "not much else" line.
(1) This was mentioned some pages back, but ... given the altitude, "high hot heavy," and location, another possibility is a bunch of birds being eaten by two engines.
Crew is playing catch up the whole way down, high task saturation, very little altitude to work with. (And I think it's rising terrain? Not familiar with the area).
That's a guess, since there's not a lot of supporting information. The FDR would be able to identify that kind of thing early in the analysis.
(2) Here's another one that is far less likely, but that also fits: bad fuel. (Didn't they just fill up after unloading from the previous flight?)
Lose one, lose two, and now you have to do your best-ever engine out drill at high gross weight and (I think?) rising terrain. (If that part is wrong, rising terrain, map study failure on my part).
Why I think it wasn't that second one.
The reported radio call about "return to field" ... but that could be for a variety of things going wrong.
More detail hopefully soon.

I don't make this post to belittle your analysis, because I think that in the main you are thinking the problem through.

I am jumping on the band wagon with lomapaseo: we might be dealing in a little bit of confirmation bias in the early reaction to this tragic loss of life.

Last edited by Lonewolf_50; 10th Mar 2019 at 20:03.
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Old 10th Mar 2019, 19:40
  #166 (permalink)  
 
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What I am pointing out is jumping on the wagon with what lomapaseo was getting at: we might be dealing in a little bit of confirmation bias in the early reaction to this tragic loss of life.
yes, that is certainly true. now, on the flip side, considering how many hours the MAX has vs hull loss.4 months to a hull loss. times 2

there is a problem.
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Old 10th Mar 2019, 19:40
  #167 (permalink)  
 
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And... B737 Max 8, RED flag,,,
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Old 10th Mar 2019, 19:42
  #168 (permalink)  
 
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Salute!
This might be a workable URL from Past Tense post above.Original may have been corrupted.
The certification issue is mentioned, as well as informing crews and such.

Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed

Gums sends...
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Old 10th Mar 2019, 19:43
  #169 (permalink)  
 
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a report of possible engine problems

https://www.timesofisrael.com/israel...medium=twitter
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Old 10th Mar 2019, 19:55
  #170 (permalink)  
 
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Originally Posted by MemberBerry View Post
Not sure exactly about which controls are you talking about, and what exactly do you mean, but as far as I know at the very least the elevator controls can be split on the 737.
There is a breakout connection between the two control columns that can disconnect if the torque applied on it becomes too high, for example if the elevator on one side of the aircraft is stuck.
Not true, there is a ruddy great toque tube that connects both elevators on the 737. You can (supposedly) disconnect the control columns, but you cannot separate the elevators. So if one jams, the other is too. Oh, and BTW, have you ever come across anyone who has done a control colum disconnect in the sim? Ever?

Face facts, the 737 would not pass certification today. Its rests its entire certification upon its 1967 grandfather rights.

Silver


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Old 10th Mar 2019, 19:57
  #171 (permalink)  
 
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Originally Posted by scr1 View Post
a report of possible engine problems
Does that not sound more like an APU issue than an engine issue?
Lack of Air Conditioning before start + unusual start procedure

Before takeoff, “the passengers understood there was a problem. It was hot, they didn’t give out water,” he said.

Israeli Ambassador to South Sudan Hanan Godar (screen capture: Channel 13)The pilot informed them of a problem with one of engines, telling them: “We’ll operate one engine to see if it catches, and if it catches, we’ll start the other engines,” Godar said.



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Old 10th Mar 2019, 19:58
  #172 (permalink)  
 
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Originally Posted by NWA SLF View Post
A CEO at a crash site is an important sign of a company commitment.
A CEO standing outside the roped-off area at a press conference is how that's normally done, as a sign of company commitment. A CEO standing in the middle of the wreckage and handling crash parts, is just setting a terrible example for others to follow.
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Old 10th Mar 2019, 19:59
  #173 (permalink)  
 
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Also a possible passenger who knows not very much about aircraft and engines. That "report" is rather low on the credibility list, given that the gent was on the aircraft on Thursday. We'll see what the FDR has (hopefully) in due course.
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Old 10th Mar 2019, 20:04
  #174 (permalink)  
 
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Originally Posted by Smythe View Post
yes, that is certainly true. now, on the flip side, considering how many hours the MAX has vs hull loss.4 months to a hull loss. times 2

there is a problem.
Or there may be two different problems. We'll see.
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Old 10th Mar 2019, 20:08
  #175 (permalink)  
 
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While those who are arguing about the CEO holding a piece of wreckage, have you seen the vidoes of 100s of locals walking over the crash site?

A message recieved from a pilot friend who was at the holding point when the doomed aircraft took off, he says that the takeoff seemed normal but shortly after the aircraft declared an emergency stating unreliable airspeed and difficulty controlling the aircraft.
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Old 10th Mar 2019, 20:12
  #176 (permalink)  
 
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Originally Posted by lomapaseo View Post
There seems to be in this thread an early fixation on a previously known cause. This flies in the face of the ability of the industry to assimilate previous causes and promulgate corrective actions world wide.
What do you expect? MCAS is a cheap (and semi-back-door) stick pusher system. It is far from ideal, but was a simple software change rather than a complete new stick-push system, which is what should have been fitted. Face facts, MCAS was a hurried and ill-thought-out fix, to yet another upgrade to a 60-year old airframe - and it is known to have already caused one tragic loss, iin very similar circumstances to the oresent incident. You think it is not justified to bring up the MCAS system again - because I have not heard that the system has been changed in any way. It is still sitting there, like a brooding gremlin, ready to pluck aircraft out of the sky at any minute.

And Boeing have still not explained the logic of of a pseudo-stick-push that keeps operating again and again and again, until you get full forward trim. Have you tried this MCAS-trim-runaway in the sim? According to the sim, the aircraft is only just about controllable with two gorillas hauling back in unison, with both feet up on the foot-bar and hauling about 40 kg pressure on each stick. And that was in level flight with the CofG in the central position. Ok, now try a recovery from a stall-dive, with a forward CofG, with 20º nose down pitch, and with the speed rapidly increasing to 250 kt. It is absolutely impossible - you are doomed. And doomed by an anti-stall system that is supposed to save you. But who in the world would want to recover from a stall, with the trim-stabiliser set fully forward? Who thought that ine up? The stabiliser is more powerful than the elevator, and will take you straight down to terra-firma. Heck, even the Wright Brothers knew not to design something like that.

Silver
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Old 10th Mar 2019, 20:13
  #177 (permalink)  
 
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Originally Posted by Lonewolf_50 View Post
I don't mean to be a wiseass, but the graph shows that it was climbing when it hit. (Or am I reading the graph incorrectly?) Is someone using non standard notation there?
I don't think you are being a wiseass - take it for what it's worth - posted on Daily Mail. Like I said, they didn't site a source. Do we really know how long it was airborne? Also doesn't seem to mirror the earlier plot posted. Compares to #56 permalink.
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Old 10th Mar 2019, 20:17
  #178 (permalink)  
 
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Originally Posted by b1lanc View Post
I don't think you are being a wiseass - take it for what it's worth - posted on Daily Mail. Like I said, they didn't site a source. Do we really know how long it was airborne? Also doesn't seem to mirror the earlier plot posted.
Thanks, I deleted my post, no value added.

Raffles S.A. Interesting. Also disconcerting. (Sounds eerily familiar to some other accidents ...)
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Old 10th Mar 2019, 20:21
  #179 (permalink)  
 
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Originally Posted by Nieuport28 View Post


IMO, the industry needs to look at this especially with the Max and the upcoming 797. I’m totally opposed to designing any inherent aerodynamic instability into a commercial airframe corrected by software. The statement from Boeing scares the hell out of me. It also scares the hell out of me that we are heading in the direction of ATP’s requiring F-35 levels of training.

MCAS was implemented due to the forward placement of the engines on the Max. Any commercial FBW aircraft should be an aerodynamically stable design. FBW should only be for control surfaces, not to allow the airframe to actually “fly.” This “improved efficiency at all cost” factor may be at a critical point.

CRM is challenging enough today.
So far I found this to be the most intelligent comment posted.
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Old 10th Mar 2019, 20:25
  #180 (permalink)  
 
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Originally Posted by Raffles S.A. View Post
W
A message recieved from a pilot friend who was at the holding point when the doomed aircraft took off, he says that the takeoff seemed normal but shortly after the aircraft declared an emergency stating unreliable airspeed and difficulty controlling the aircraft.
First time I hear this in respect to this accident. If true, that'd be another indication pointing to MCAS in combination with erroneous sensor data.
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