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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 10th Mar 2019, 21:34
  #181 (permalink)  
 
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I’m pondering crew composition. On the one hand an experienced pilot although not ‘vastly’ so, on the other a new guy apparently fresh out of training (200hrs). If (BIG IF) this was one of the more unusual failure scenarios, you have to feel for the CRM side of the house.
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Old 10th Mar 2019, 21:48
  #182 (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.
Honestly, I think you are wrong.
1. FBW is exactly for that purpose. Not only, but for that too. To steer what is unstable. B2 Spirit nuclear bomber couldn't fly by a mile without FBW. It's great system and failed (probably) only once in all history.
And correction for aerodynamics in software is mandatory. For example, you can't build two exactly the same wings for A380. So without software correction in systems a/c can't fly in straight line by holding yoke/stick one position.
2. None of 737 is FBW equipped, including MAX. series (and that's a source of the problem IMO)



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Old 10th Mar 2019, 21:53
  #183 (permalink)  
 
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Originally Posted by wobblywings View Post
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.
I'm pretty sure the ATC tapes will be analyzed. Remember that only about 20% of posts here contribute something valuable to the conversation and this is exactly what it is, a conversation.
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Old 10th Mar 2019, 21:58
  #184 (permalink)  
 
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2. None of 737 is FBW equipped, including MAX. series (and that's a source of the problem IMO)
MAX roll spoilers are FBW. Emergency descends and approach speed management are FBW assisted.
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Old 10th Mar 2019, 22:13
  #185 (permalink)  
 
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Originally Posted by gums View Post
Salute!

@Gilles

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....
Possibly off topic, but, why would brand new aircraft sensors and indicators fail within months? The software, MCAS, is reliant on good data, if the data was always good then there wouldn't be a problem with the software. The question is, why is the data so bad? Why is MCAS reliant on AOA sensors that fail within months of introduction? Yes, I agree that MCAS shouldn't have been slipped in by the backdoor, but we probably still wouldn't know much about it if it was actually functioning the way it was supposed to! Are all these billions of dollars spent on automation software being pumped into unreliable hardware?

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.

I'm not jumping the gun, and certainly not claiming this was the problem with this flight, just picking up on others comments on MCAS.
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Old 10th Mar 2019, 22:13
  #186 (permalink)  
 
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Clear day

It has to be more than just unreliable airspeed or the MCAS issue. Every pilot on the MAX must be versed in what happens with MCAS.

its a clear day, and if you can’t just grab the throttles and yolk and get your eyes out the window, while PNF cleans up the configuration - something very wrong had to happen. It must be something exceptional like a double bird strike creating partial power.
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Old 10th Mar 2019, 22:23
  #187 (permalink)  
 
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Have you tried this MCAS-trim-Runway 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.

Silver
So, you just took off, engines still at TO power, you retract the flaps... and start fighting Mcas as per above description. No time to manage engine power so you are gaining speed...
you remember mcas. Somehow you pull the circuir breaker. With both pilots pulling the stick the plane now goes into a steep climb. Followed by stall, and crash due to unsuccessful recovery...

Could it match, in theory?
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Old 10th Mar 2019, 22:26
  #188 (permalink)  
 
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Originally Posted by Hibernia View Post
777 crew behind ET302 at holding point report observing normal takeoff followed shortly by declaration of emergency. They heard ET302 on tower frequency transmitting “Wrong airspeed indications and difficulty controlling aircraft.”
Which is much the same as the Indonesian Max.
The airspeed was ok, of course, but the stick shaker going off and the MCAS anti-stall trim going off, tends to make you think the airspeed is wrong. So how much of a briefing have Max crews been given, on the inadvertent operation of the MCAS system?

Touch of the deja-vus, I would say. See my comment above, about the absurdity of the MCAS system.

Silver


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Old 10th Mar 2019, 22:38
  #189 (permalink)  
 
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Originally Posted by Lonewolf_50 View Post
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.
...
(2) Here's another one that is far less likely, but that also fits: bad fuel.
While I wouldn't rule out anything at this point in time at least the FR24 data indicates that engines seemed to deliver power. Aircraft sped up to 383kts but was apparently never able to gain altitude. Even considering ambiguities and inaccuracies in FR24 data it appears the never got over 1000ft above ground while spearing along at a breathtaking 383kts. That is fighter jet low attack profile and does not really point big time towards engine trouble. The level of devastation also points towards a very high energy impact. This also rather contradicts any loss of propulsion scenarios.
Sadly, this carries many similarities with the other MAX Crash.
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Old 10th Mar 2019, 22:42
  #190 (permalink)  
 
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MAX 8 series drivers: is the timing of the intermittent operation of MCAS compatible with the timing interval for the vertical speed drops reported by FR24, in particular the first two pitch downs?
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Old 10th Mar 2019, 22:43
  #191 (permalink)  
 
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If it's true that the MCAS only becomes active after flap retraction then I doubt it was involved in this instance. Acceleration (and thus flap retraction) doesn't happen until at least 1500' AGL, and it looks like this flight never even attained that height.
That is only based on the ADS B data online which may be inaccurate so only time will tell.
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Old 10th Mar 2019, 22:47
  #192 (permalink)  
 
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Originally Posted by derjodel View Post
So, you just took off, engines still at TO power, you retract the flaps... and start fighting Mcas as per above description. No time to manage engine power so you are gaining speed...
you remember mcas. Somehow you pull the circuir breaker. With both pilots pulling the stick the plane now goes into a steep climb. Followed by stall, and crash due to unsuccessful recovery...
Could it match, in theory?


Could be correct.

You see after take off the normal speed-trim system is always trimming anyway, so you are used to that 1930s (borrowed from the Ju-52) trim-wheel clanking and rotating. So it may take you a while to realise the trim is doing something very wrong.

Plus if the MCAS system is at fault again, you will have the stick shaker going off, which makes a hell of a racket, and is not cancellable. The stick shaker is supposed to be transient, just for the stall, but if yet another AoA vane has failed, the shaker will go off continuously, and is a serious distraction.

Plus you go for the stab-trim cutout switches, and you forget they are down for off, while all the other switches on the 737 are up for off. (Why is Boeing so stupid...?) So you shout to the f/o, above the noise of the shaker and the trimmer, 'did you turn the stab-tim switches off', to which he-she replies 'yes' - meaning he placed the switches upwards. But this turns the trim on, not off.

And then you reduce power, and the huge thrust-couple change plunges the nose downwards. So now the aircraft now has full trim forward, and is plunging to the ground like a home-sick troglodyte. (When does an aircraft ever want full trim?) And two people pulling on the stick is no longer sufficient to stop the dive. And Boeing thinks this is a great system to fit to a modern airliner, and a great ergonomic design for the 21st century? I have got news for Boeing....

And yes, this discussion is justified, because Boeing never gave any answers to the last crash. And nor, so far as I know, have they made any amendments to MCAS. So the 737-Max is still fitted with a system that will give full trim forward, and make the aircraft uncontrollable. Why is that? Does Boeing have an explanation for this - for why any aircraft would want full trim forward while pulling out of a stall's subsequent dive??

Silver



.
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Old 10th Mar 2019, 22:49
  #193 (permalink)  
 
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Given how much all of the armchair experts on this forum seem to know about MCAS, it is extremely hard to believe that a B737-Max8 pilot who flies for a competent operator (and ET is in that group) would be oblivious to MCAS' effects and the way to stop them. Surely all of these pilots would have been deluged with training information about MCAS issues over the last several months. Indeed, given MCAS' recent infamy, I think it is more likely that pilots are now misinterpreting nonMCAS faults to be an MCAS ones than vice versa.
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Old 10th Mar 2019, 23:00
  #194 (permalink)  
 
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Originally Posted by oceancrosser View Post
It is my understanding that the 737MAX spits out a lot of data at short intervals via ACARS to maintenance systems (Boeing). If that applies to ET, Boeing should already have an idea what systems played a role in this accident. Anyone with more info on this?
Also be useful to know which data is correct. The data publicised so far is ADS-B, so if it is an onboard sensor problem causing bad data to flight control, then surely some of the FR data is bad too?
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Old 10th Mar 2019, 23:02
  #195 (permalink)  
 
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Originally Posted by SeenItAll View Post
Given how much all of the armchair experts on this forum seem to know about MCAS, it is extremely hard to believe that a B737-Max8 pilot who flies for a competent operator (and ET is in that group) would be oblivious to MCAS' effects and the way to stop them. Surely all of these pilots would have been deluged with training information about MCAS issues over the last several months. Indeed, given MCAS' recent infamy, I think it is more likely that pilots are now misinterpreting nonMCAS faults to be an MCAS ones than vice versa.

First mistake is to assume Pilots are deluged with Variant specific training and technical support. It’s woeful and inadequate in 90% of airlines. The accountants and sales office at Boeing have won the battle.. the lawyers have written the manuals and training package..

very sad sad state of affairs in most airlines

love the speculation about the non-normals, MCAS etc.. all nearly correct but very far from reality
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Old 10th Mar 2019, 23:14
  #196 (permalink)  
 
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Originally Posted by QDM360 View Post
According to the same ADS-B data they were eventually flying with 383kts. They surely should have retracted flaps before accelerating to 383kts...
+1
With full slats and extended flaps it simply won't reach 383kts. So it is safe to assume they were retracted. And it is also pretty safe to assume they did not spear along on autopilot at below 1000ft - I'm not aware there is a TFR in a 737 MAX...
So both conditions for MCAS being active were pretty surely met in this case.
Does it mean MCAS was surely the cause? No.
Does it point into that rough general direction? Rather Yes.
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Old 10th Mar 2019, 23:39
  #197 (permalink)  
A4

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1. Does MCAS require a fully clean wing or just flaps at 0? (i.e. Slats still extended).
2. Does the 738/Max have auto flap retract á la Airbus - on the Bus the flaps auto retract as speed increases (for protection).
3. Are the auto trim on/off switches guarded?
4. What state is the Auto throttle in after take off? Does it have to manually activated at thrust reduction altitude?
5. If the throttle levers are left untouched after take off, with a distraction (UAS) would thrust remain at take off thrust setting?

A4
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Old 10th Mar 2019, 23:42
  #198 (permalink)  
 
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Learned Contributors,
please excuse if this is considered thread drift. If this Ethiopian crash and the Indonesian previously covered on here are proved to be linked. Is
not it odd that out of the total number of B.738M departures since entry to service, no one has been subject to this upset and caught it without loss of life ? Especially since Indonesia as I expect all B.738 Max crews are looking out for a recurrence?
Your time and trouble much appreciated,
Be lucky
David
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Old 10th Mar 2019, 23:43
  #199 (permalink)  
 
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Salute!

@Nieuport28, fsfaludi & silverstrata
Right on!

@klintE
Honestly, I think you, klintE are wrong.

As prolly the oldest pure FBW pilot here ( unless you were a Concorde dude or flew a test plane back in 1979), I wanna clear up the gross misunderstanding about FBW that many folks still have and exhibit.
And correction for aerodynamics in software is mandatory
No so. You can have a perfectly good B-17 and simply replace all the cables and such to each control surface, and maybe the horizontal stab with a single hydraulic line and a hydraulic actuator commanded by some wires. This is opposed to the original irreversible hydraulic flight control systems we saw in the 50's and later in most of the "fast jets" ( as the Brits say). No direct feedback but a few attempts to help. In other words, no ropes, pulleys, tubes, cables, etc.
Although you can use the FBW implementation for better stability, stall prevention and gee limits and ..... that's not the sole reason for FBW. And the new F-35 doesn't even have hydraulic lines to the surface actuators - they are electrically driven, local hydraulic or electric actuators. They are truly "electric jets", even tho we called my old Viper the original "electric jet"..

The B-2 FBW system did, indeed, command a bad pitch after WoW due to sensor contamination by water. Simple maintenance procedures and crew actions prevented future occurences.
The AF447 FBW system did not fail due a bad sensor. It commanded pitch trim so the pilot would not have to keep holding back stick, which he did for a long time, even after the other guy said they were climbing.

Lastly, there's at least one flight control surface on the 737 that is FBW.

Let's face it, the new mod to the very old plane that was certified 50 years ago would not have been certified back then. I have looked closely at the U.S. Part 25 requirements for trim, stall conditions, etc and I have a hard time believing the MAX version was certified.

Gums opines...
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Old 10th Mar 2019, 23:44
  #200 (permalink)  
 
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Originally Posted by SeenItAll View Post
Given how much all of the armchair experts on this forum seem to know about MCAS, it is extremely hard to believe that a B737-Max8 pilot who flies for a competent operator (and ET is in that group) would be oblivious to MCAS' effects and the way to stop them. Surely all of these pilots would have been deluged with training information about MCAS issues over the last several months. Indeed, given MCAS' recent infamy, I think it is more likely that pilots are now misinterpreting nonMCAS faults to be an MCAS ones than vice versa.
Not to mention the fact that the guys flying the Lion Air plane the day before (UK captain) had the same problem as the accident flight, hit the STAB TRIM CUTOUT switches and went on about their day. Even if this is MCAS, again, and even if it was the same for Lion Air, I still believe 100% that a US or European crew wouldn't have had any problem at all. A new captain and a 200-hour wonder is the absolute worst possible combination here... just saying.
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