morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 10:31 pm

Waterbomber2 wrote:
tropical wrote:
Whereas it is still possible that once the final report comes out it might rule human error might have been *partially* to blame (even though it is looking less likely by the day to me, but never mind that for now), surely it is beyond any doubt by now that Boeing will certainly shoulder a significant amount of the blame overall in this sorry saga?

In view of that, perhaps it is time for anyone still trying to find alternative (and increasingly desperate) scenarios that might suggest pilot error was responsible to reconsider and stop trying to shift the focus of the discussion to it. That Boeing has made a series of serious errors of judgment throughout the conception and implementation of the MAX is both undeniable and the root of the problem here. Even if deficient training or maintenance turned out to have played a part in either crash, it would still be a footnote to the core issue here.


It definitely looks that way.
To me, a non-FBW aircraft that can't be trimmed manually within its flight envelope raises question marks.


But it wasn't within its flight envelope.
 
Interested
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 10:35 pm

RickNRoll wrote:
scbriml wrote:
qf789 wrote:
Here is Boeing's statement on the investigation preliminary report

http://www.boeing.com/commercial/737max ... /statement


"The preliminary report contains flight data recorder information indicating the airplane had an erroneous angle of attack sensor input that activated the Maneuvering Characteristics Augmentation System (MCAS) function during the flight, as it had during the Lion Air 610 flight."

That lays to rest any lingering doubts that MCAS was involved in both accidents and that the grounding wasn't justified.
Like i just said, from Boeing themselves.
"


"To ensure unintended MCAS activation will not occur again, Boeing has developed and is planning to build a new plane that doesn't need MCAS"

Above I've edited the Boeing quote to make us all far safer from now on
 
morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 10:39 pm

sadiqutp wrote:
I find it extremely disturbing the amount of focus is given to pilots actions rather than control systems...
You see, I am not saying the pilots did everything correctly or otherwise, I don't think the preliminary report give enough information to draw that conclusion.
But here is what I know.
1- MCAS is designed based on one input structure.. No redundancy.. That's on Boeing
2- This is not the first accident of the same cause, not only did Boeing relieved themselves of responsibility after the first one, but had failed to address it before it claimed other casualties. That's on Boeing
3- A new system was introduced to a new version of a series that would alter flight controls when AP is disengaged.. Pilots were neither informed nor trained to deal with new system.. That's on Boeing

I still think the actions of pilots should further be scrutinised, not for blame, but rather to improve training and safety.

I also believe, the conversation in here is extremely imbalanced and Boeing enthusiasts should admit that Boeing could've done better. I am sure the Max will be back in the air, but safely shouldn't be a compromise, again!

Until then, RIP to all those perished



I would pretty well agree with most of this post - in retrospect #2 is now obvious and Boeing should not have expected the level of proficiency they assumed MAX pilots had. Apparently Airbus agrees and hence why they are establishing there pilot schools.

And I really hope these incidents really help to improve safety and training and certification standards.
 
Waterbomber2
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 10:41 pm

I think that Boeing should set the corporate talk aside and offer families of the victims sufficient compensation as goodwill, so they won't need to worry about money in their lifetimes.
The CEO recording that video is a good first step, they promise to get the fix right.
I want to hear that the loved ones of the victims will be taken care of so that they won't have to go through the painstaking process of fighting this in court for years to come.

Lufthansa offered just a miserable 75.000 EUR per victim compensation for the Germanwings crash where the pilot was the MCAS, despite reporting billions in profits.
 
eidvm
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 10:42 pm

Waterbomber2 wrote:

Mmmm you are pulling with full force and 94% N1 to stay level in a very narrow flight envelope.
If you reduce thrust in that setting your aircraft is going to pitch down because the engines are actually helping you to stay level.

Reducing thrust is easier said than done, that's very counter-intuitive.
Sorry but manual trim should remain operable through the entire flight envelope of an aircraft.

It looks like an ADIRS left failure (could be sensors, could be downstream) caused MCAS to trim down. They switched MCAS off but the increasing speed cornered the pilots in that they couldn't counteract with elevators nor trim up anymore. Reducing speed could have helped them regain control of the manual trim at the expense of altitude but that is a suicide mission. You don't know if manual trim is going to work again if you do reduce the speed.
So they tried to trim their way out, perhaps by reactivating electrical trim and then MCAS put them in their final dive.

I would probably have done the same in their position.


This post sums it up perfectly.

Reducing thrust induces further aircraft pitch down.

The pitch power couple on a 737 is quite strong, stronger by all accounts on the MAX. Pitch/Power couple is an immediate reaction on the airframe and would result in an immediate further nose down moment. Airspeed would take a number of seconds if not minutes to bleed off, time this crew did not have at the altitude they were at.

They were faced with a Catch 22, reduce thrust, which would increase Aircraft Nose Down Moment forces, or maintain thrust and hope to find an alternative solution, all the while the aerodynamic loading on the tailplane would increase as airspeed increased.

Also another poster suggested that reducing thrust would reduce aerodynamic loading on the stabiliser, this is not the case, reducing back pressure on the stick or reducing airspeed would reduce aerodynamic loading on the stabiliser, not reducing thrust. Were the aircraft controllable, eventually the result of reducing thrust would be reduced speed which would in turn allow the trim to be manually cranked, however time was limited and likely the crew did not have the altitude to trade by bringing engine power back which would have resulted in a nose down moment force.
 
TravelbyAir
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 10:46 pm

afgeneral wrote:
Waterbomber2 wrote:
There is one thing the flight crew could have done but it's a bit insane. They could have treated this as being out of CG (excessively fwd CG) and ordered pax in the first 3 rows to run back to the aft galley and stay there until further notice.
2 tons shifting from all the way in the front to all the way in the back would create sufficient momentum to pitch the aircraft up.

Again, not saying they should have done this as it's insane, but this may have been their last option.
And again, I suggest this with hindsight, time to see the data and gain awareness, no bells and whistles going off and from a comfy chair safely on the ground.


that's like saying pilots of an aircraft suffering from a fire should command passengers to start spitting and pissing on the fire until it is put out

As a passenger I'd do that if the water, beer and wine ran out.
 
sadiqutp
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 10:55 pm

morrisond wrote:
I would pretty well agree with most of this post - in retrospect #2 is now obvious and Boeing should not have expected the level of proficiency they assumed MAX pilots had. Apparently Airbus agrees and hence why they are establishing there pilot schools.

And I really hope these incidents really help to improve safety and training and certification standards.


I disagree, I don't think the problem is pilot's low level of proficiency to deal control systems. I think it's Boeing's introduction of control systems without enough information or training.
 
KingOrGod
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 10:55 pm

morrisond wrote:
Waterbomber2 wrote:
tropical wrote:
Whereas it is still possible that once the final report comes out it might rule human error might have been *partially* to blame (even though it is looking less likely by the day to me, but never mind that for now), surely it is beyond any doubt by now that Boeing will certainly shoulder a significant amount of the blame overall in this sorry saga?

In view of that, perhaps it is time for anyone still trying to find alternative (and increasingly desperate) scenarios that might suggest pilot error was responsible to reconsider and stop trying to shift the focus of the discussion to it. That Boeing has made a series of serious errors of judgment throughout the conception and implementation of the MAX is both undeniable and the root of the problem here. Even if deficient training or maintenance turned out to have played a part in either crash, it would still be a footnote to the core issue here.


It definitely looks that way.
To me, a non-FBW aircraft that can't be trimmed manually within its flight envelope raises question marks.


But it wasn't within its flight envelope.


In what way?
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 11:00 pm

XRAYretired wrote:

MCAS active can only be inferred by autrotrim down (FLAPS UP, AP OFF). This ship did not have AOA angle indicator, so a trim can only be set by feel and other visual references.

Ray

Trim can be set using the trim indicator or the attitude indicator combined with control forces feel.
Phrogs Phorever
 
TaromA380
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 11:02 pm

Interested wrote:
But at that stage I think it's accepted they had no control over the plane and the Boeing procedures to reclaim control of the plane had failed?

So what else could they have gambled on

It appears reducing speed is not one of the gambles

What else could they try at this stage?

Aren't they doomed anyway by now?

They've tried the checklist repeatedly and its failed them?

1. There is no such thing as "it's [universally] accepted".

2. I'm just a naive aviation fan, but after reading that preliminary report, if I were Boeing I would call "as accepted" the fact that nobody but the pilots allowed the development of extreme airspeed where no human forces could counteract anymore the control surfaces. "This is not faulty design but basic physics laws". Then I would point as determinant (of course) the apparent cockpit mismanagement where the electric trim was re enabled chaotically then blatantly mishandled. A Boeing defender would tell that a good pilot communication followed by proper handling with that little switch would have avoided the crash. If I were the Airline, I would tell another story (of course), more like yours.

3. From what I read here and there, there is (?) a procedure of 75% N1 throttles or something like that, when malfunctioning speed sensors or loss of references. If it exists and is valid even for reduced altitude like 5000ft - which means the possible/risk of some slight initial nose down is considered (and someone even posted here that a Max wouldn’t have nose down at all in that particular situation), then someone can focus on this apparent lack of acting properly.

4. “But the pilots were disoriented by the…” this also can be interpreted both ways, and human behavior is not quantifiable like speed and altitude – it’s so empiric and subjective.
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 11:08 pm

KingOrGod wrote:
morrisond wrote:

But it wasn't within its flight envelope.


In what way?

They were at least 25-30 knots over Vmo
Phrogs Phorever
 
Interested
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 11:10 pm

TaromA380 wrote:
Interested wrote:
But at that stage I think it's accepted they had no control over the plane and the Boeing procedures to reclaim control of the plane had failed?

So what else could they have gambled on

It appears reducing speed is not one of the gambles

What else could they try at this stage?

Aren't they doomed anyway by now?

They've tried the checklist repeatedly and its failed them?

1. There is no such thing as "it's [universally] accepted".

2. I'm just a naive aviation fan, but after reading that preliminary report, if I were Boeing I would call "as accepted" the fact that nobody but the pilots allowed the development of extreme airspeed where no human forces could counteract anymore the control surfaces. "This is not faulty design but basic physics laws". Then I would point as determinant (of course) the apparent cockpit mismanagement where the electric trim was re enabled chaotically then blatantly mishandled. A Boeing defender would tell that a good pilot communication followed by proper handling with that little switch would have avoided the crash. If I were the Airline, I would tell another story (of course), more like yours.

3. From what I read here and there, there is (?) a procedure of 75% N1 throttles or something like that, when malfunctioning speed sensors or loss of references. If it exists and is valid even for reduced altitude like 5000ft - which means the possible/risk of some slight initial nose down is considered (and someone even posted here that a Max wouldn’t have nose down at all in that particular situation), then someone can focus on this apparent lack of acting properly.

4. “But the pilots were disoriented by the…” this also can be interpreted both ways, and human behavior is not quantifiable like speed and altitude – it’s so empiric and subjective.


The fact is the world knows this is a Boeing problem and not a pilot problem

I get your points but I think in this case it's pretty clear cut where the major issues lie

This really isn't a crash that will be considered pilot error in any serious way. Let's be realistic.
 
rusti999
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 11:34 pm

TaromA380 wrote:
3. From what I read here and there, there is (?) a procedure of 75% N1 throttles or something like that, when malfunctioning speed sensors or loss of references. If it exists and is valid even for reduced altitude like 5000ft - which means the possible/risk of some slight initial nose down is considered (and someone even posted here that a Max wouldn’t have nose down at all in that particular situation), then someone can focus on this apparent lack of acting properly.


This seems to be part of the memory item for 737 in the case of unreliable airspeed, which actually occurred right when the left stick shaker got activated shortly after takeoff, according to the report. Despite the left stick shaker and the AoA-derived values (including airspeed) on the captain's side deviating, it seems that the flight deck crew were planning to continue like normal, as indicated by the fact that the autopilot was turned on (15 seconds after the left stick shaker activation) and the flaps got retracted (38 seconds after the left stick shaker activation). Was this wise?
 
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remcor
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 11:46 pm

dragon6172 wrote:
Interested wrote:
Meaning reduce thrust, reduce airspeed, maybe gain some ability to move the trim wheel manually.

It would appear they chose to re-engage electric trim to try and reduce control forces. Which I am ok with, but they didnt follow thru and actually move the trim any useful amount. Why?


They probably weren't familiar with the uber-high forces needed to move the trim wheel in such a condition. Certainly they weren't expecting it since Boeing wasn't even expecting it.
Also, reducing airspeed without pitch effectiveness isn't trivial. If you slow down the airplane will pitch down (this goes for basically all airplanes, not just the 737). If they were just a few thousand feet over the ground they may have had no margin.

As far as why they didn't trim more when they re-engaged electric trim? good question. Maybe they could have turned it on to manually trim, then turned it off as soon as the MCAS kicked in, and repeated?. In any case it's easy to say down here on the ground knowing exactly what happened afterwards.
 
multimark
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 11:54 pm

Interested wrote:

Yep and in 2019 with a plane that should be state of the art

We've ended up with that suggestion as to how to save the plane

It says it all really!!


Well, that's the problem: it is 2019 but you're dealing with an airframe whose basic design first entered revenue service in 1968.
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thu Apr 04, 2019 11:55 pm

remcor wrote:
They probably weren't familiar with the uber-high forces needed to move the trim wheel in such a condition. Certainly they weren't expecting it since Boeing wasn't even expecting it.
Also, reducing airspeed without pitch effectiveness isn't trivial. If you slow down the airplane will pitch down (this goes for basically all airplanes, not just the 737). If they were just a few thousand feet over the ground they may have had no margin.

As far as why they didn't trim more when they re-engaged electric trim? good question. Maybe they could have turned it on to manually trim, then turned it off as soon as the MCAS kicked in, and repeated?. In any case it's easy to say down here on the ground knowing exactly what happened afterwards.

They dont have to reduce throttles so much to enter a descent. As I said, they were in a 2000 fpm climb. Pull the throttle back until level off.
And, there wouldn't be a need to turn trim on and off repeatedly. Turn it back on, trim it all the way to where needed, turn it off. There is no limit to how long the pilot can make trim inputs. MCAS inputs do not override pilot inputs.
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B737900ER
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 12:02 am

Interested wrote:
sadiqutp wrote:
morrisond wrote:
I would pretty well agree with most of this post - in retrospect #2 is now obvious and Boeing should not have expected the level of proficiency they assumed MAX pilots had. Apparently Airbus agrees and hence why they are establishing there pilot schools.

And I really hope these incidents really help to improve safety and training and certification standards.


I disagree, I don't think the problem is pilot's low level of proficiency to deal control systems. I think it's Boeing's introduction of control systems without enough information or training.


Yep - those pilots seemed to follow their procedures as well as anyone could have expected

Plane designers are supposed to design planes that average pilots can fly safely

These guys performed at least average

If they hadn't they would be getting absolutely hammered on here

The Boeing apologists have actually seriously struggled to find things to criticise


I don’t think you understand aviation accidents. There is NEVER a single point of failure. There’s probably 11 different things that went wrong on that flight. Once again is a faulty flight control system to blame? Yes. Are pilot actions to blame? Yes. If it comes to light that some fod caused damage, is that to blame? Yes. Is having a massively inexperienced pilot at the controls of an aircraft nobody has been well trained on during an emergency situation to blame? Yes. As well as a dozen other factors.

What happened was tragic. Pointing fingers at the crew or Boeing or whoever as if one action and one action only is to blame is naive and pointless. The industry was built on leading from these kinds of incidents. We’ll learn from it and make things safer. This is in no way the last plane crash. There will be others. But they will happen less frequently as we build off the lessons learned here.
 
Exeiowa
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 12:09 am

The only thing the pilots are guilty of is not being lucky. They had limited opportunity to fix the unknown problem. That probably meant one shot under pressure, their guess did not work out. I think I would rather have planes that do not require luck. The plane itself was completely flyable, the system made it unflyable. They follow the procesure but did not get the expected outcome. Peoples suggestions of what they should have done instead, are untested, and probably you took longer to type it out that the pilots had to figure it out and implement while doing other stuff after hitting the switch did not leave them in a good place (I specifically mentioned that being why I didnt like that solution a few weeks ago). As for overspeed if I read the report correctly they initiated take off with auto pilot and disengaged after take off. Maybe the overspeed was a consequence of intial autopilot commands based on a miss reporting pitot tube (or whatever else might be giving speed indication) as a second effect of a bird strike that also hit the AoA sensor.
 
acechip
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 12:17 am

How many examples in commercial aviation exist where the plane has a control system to correct an inherently unstable aerodynamic situation (by design) ?
 
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remcor
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 12:28 am

dragon6172 wrote:
remcor wrote:
They dont have to reduce throttles so much to enter a descent. As I said, they were in a 2000 fpm climb. Pull the throttle back until level off.
And, there wouldn't be a need to turn trim on and off repeatedly. Turn it back on, trim it all the way to where needed, turn it off. There is no limit to how long the pilot can make trim inputs. MCAS inputs do not override pilot inputs.


But why would they even want to reduce airspeed, especially if it meant trading for precious altitude? Why would this be a priority?

Like I mentioned before, with a fixed trim/elevator setting, increasing airspeed should tend to pitch the nose upward. And considering the entire problem was uncontrollable nose-down pitch, increasing airspeed makes a degree of sense too.
 
hivue
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 12:43 am

Etheereal wrote:
It would have to be the following:
Re engage STAB TRIM CUTOFF switches.
Electric trim to desire level.
CUT OFF SWITCHES before 5 seconds pass (or MCAS will nose down again IF AoA sensor is still at fault).


Unfortunately it appears they were unable to "Electric trim to desire level" and so never made it to "CUT OFF SWITCHES before 5 seconds pass (or MCAS will nose down again IF AoA sensor is still at fault)."
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
Aviation737
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 12:44 am

So the question that I have is why were the crew of the previous Lion Air fight (the flight before JT610) were able to save the plane while the Ethiopian flight didn't? To me, both flights seem they were in similar conditions as both flight crews managed to turn off the stab trim switches according to my understanding.
 
rusti999
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 12:46 am

remcor wrote:
But why would they even want to reduce airspeed, especially if it meant trading for precious altitude? Why would this be a priority?

Like I mentioned before, with a fixed trim/elevator setting, increasing airspeed should tend to pitch the nose upward. And considering the entire problem was uncontrollable nose-down pitch, increasing airspeed makes a degree of sense too.


One consideration: they were getting close to or even exceeding the maximum operating speed of the aircraft, surpassing the design limits of the aircraft, at which point all bets are off. The initial overspeed warning started a full 2 minutes prior to the final trim down command from MCAS at 05:43:20 (after the electric trim was seemingly restored). Had they addressed the speed issue then, maybe the chance of recovery would be higher. There actually weren't any MCAS commands in the span of almost three minutes (between 05:40:41 and 05:43:20), but in this period, it got harder and harder to adjust the trim manually because the plane was getting faster.
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 12:58 am

hivue wrote:
Etheereal wrote:
It would have to be the following:
Re engage STAB TRIM CUTOFF switches.
Electric trim to desire level.
CUT OFF SWITCHES before 5 seconds pass (or MCAS will nose down again IF AoA sensor is still at fault).


Unfortunately it appears they were unable to "Electric trim to desire level" and so never made it to "CUT OFF SWITCHES before 5 seconds pass (or MCAS will nose down again IF AoA sensor is still at fault)."

This is false. Pilot inputs have PRIORITY over MCAS.
MCAS does not override pilot trim inputs. It has been said hundreds of times. The pilot could hold the trim switch to the full nose up position with no MCAS interruption.
Phrogs Phorever
 
spacecadet
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 12:59 am

remcor wrote:
spacecadet wrote:
remcor wrote:
You guys are saying REDUCE AIRSPEED like it's a given. So how would one reduce airspeed in the current situation?


Speed brakes, flaps, landing gear...

Not saying they had a way out of the situation, but as for this specific question, yes, there are ways to reduce airspeed in an airliner besides just reducing throttle and pitching up. Otherwise no airliner could ever land.


Still, all would cause the nose to pitch down.


Flaps change the wing chord line and actually cause it to "pitch up" (the fuselage may not, but the wing does) until speed is reduced enough for it to pitch down. If flying manually, you actually need to push the nose down to maintain altitude when deploying flaps - otherwise you will balloon. At the speeds they thought they were at, deploying flaps would not be something you'd normally want to do. But in an emergency situation where the checklists aren't working and you're improvising, all options are on the table.

Anyway, it depends on what the goal is at any given time. From the sound of it, they had a 2000fpm ascent going when they turned the trim system back on. I'm just unclear on what they were actually trying to do - it seems like they thought they were overspeeding, so I don't know how retrimming is going to help that. I guess they must have thought the problem was really the engines or airspeed indicators, and they wanted even more of a pitch up. Clearly, whether they should have known it or not, switching the trim system back on was not the right thing to do because it led to an accident. They weren't following a checklist or procedure at that point. I'm sure it was a confusing situation, but they seemed to be improvising at that point and just got it wrong.

Of course the MCAS system is at least partly to blame - I don't think that's a question anymore - but based on this initial report, there are definitely still questions about what the pilots were doing and why. As someone else said above, almost no accident has a single cause.
I'm tired of being a wanna-be league bowler. I wanna be a league bowler!
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 1:03 am

Aviation737 wrote:
So the question that I have is why were the crew of the previous Lion Air fight (the flight before JT610) were able to save the plane while the Ethiopian flight didn't? To me, both flights seem they were in similar conditions as both flight crews managed to turn off the stab trim switches according to my understanding.

Because they trimmed to a more normal 5.0 units of trim before turning it off.
Phrogs Phorever
 
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NeBaNi
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 1:06 am

sadiqutp wrote:
morrisond wrote:
I would pretty well agree with most of this post - in retrospect #2 is now obvious and Boeing should not have expected the level of proficiency they assumed MAX pilots had. Apparently Airbus agrees and hence why they are establishing there pilot schools.

And I really hope these incidents really help to improve safety and training and certification standards.


I disagree, I don't think the problem is pilot's low level of proficiency to deal control systems. I think it's Boeing's introduction of control systems without enough information or training.

I think I pointed this out earlier in this thread in a reply to morrisond but here's another try (I know I'm simplifying things here):
I don't think it's a proficiency issue as much as a crew workload issue, and hence, a certification issue. Aircraft certification requires that for an aircraft to be certified, the flight crew can only be subjected to excessive workloads like that once per million (q=10^-9). We know that the workload was excessive in both cases, because a similar previous Lionair flight required an off-duty pilot to diagnose and solve the problem.
 
Exeiowa
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 1:11 am

Although I have not seen it explicitly stated I am wondering if the first Lion air flight with the problem had the benefit of height before the problem occured making it substantially easier to find the fix in time with the additional crew member.
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 1:12 am

Exeiowa wrote:
Although I have not seen it explicitly stated I am wondering if the first Lion air flight with the problem had the benefit of height before the problem occured making it substantially easier to find the fix in time with the additional crew member.

Height? They were around 1500 feet when they got the first MCAS input
Phrogs Phorever
 
TravelbyAir
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 1:13 am

dragon6172 wrote:
hivue wrote:
Etheereal wrote:
It would have to be the following:
Re engage STAB TRIM CUTOFF switches.
Electric trim to desire level.
CUT OFF SWITCHES before 5 seconds pass (or MCAS will nose down again IF AoA sensor is still at fault).


Unfortunately it appears they were unable to "Electric trim to desire level" and so never made it to "CUT OFF SWITCHES before 5 seconds pass (or MCAS will nose down again IF AoA sensor is still at fault)."

This is false. Pilot inputs have PRIORITY over MCAS.
MCAS does not override pilot trim inputs. It has been said hundreds of times. The pilot could hold the trim switch to the full nose up position with no MCAS interruption.
[quote="Etheereal"][quote="Interested"][quote="hivue"]
Is this known FOR CERTAIN, that MCAS doesn't override manual electric trim switches? Not challenging anyone, just curious if this is definitively known, or just a presumption at this point.

Obviously if not, that's a giant problem if you can only trim up during the MCAS pause.
 
morrisond
Posts: 1123
Joined: Thu Jan 07, 2010 12:22 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 1:40 am

B737900ER wrote:
Interested wrote:
sadiqutp wrote:

I disagree, I don't think the problem is pilot's low level of proficiency to deal control systems. I think it's Boeing's introduction of control systems without enough information or training.


Yep - those pilots seemed to follow their procedures as well as anyone could have expected

Plane designers are supposed to design planes that average pilots can fly safely

These guys performed at least average

If they hadn't they would be getting absolutely hammered on here

The Boeing apologists have actually seriously struggled to find things to criticise


I don’t think you understand aviation accidents. There is NEVER a single point of failure. There’s probably 11 different things that went wrong on that flight. Once again is a faulty flight control system to blame? Yes. Are pilot actions to blame? Yes. If it comes to light that some fod caused damage, is that to blame? Yes. Is having a massively inexperienced pilot at the controls of an aircraft nobody has been well trained on during an emergency situation to blame? Yes. As well as a dozen other factors.

What happened was tragic. Pointing fingers at the crew or Boeing or whoever as if one action and one action only is to blame is naive and pointless. The industry was built on leading from these kinds of incidents. We’ll learn from it and make things safer. This is in no way the last plane crash. There will be others. But they will happen less frequently as we build off the lessons learned here.


Great post - I agree 100% It was a combination of many factors. Boeing and Pilots.

BTW - The FO of that plane had less hours than I do (he was at 98 hours(or 154 the report is a little unclear) - I got to about 110 total before stopping 10 years ago)before he was made a FO of an 737. If you don't think I know what I'm talking about - well someone with less hours (or slightly more) was made a FO of a 737.

In that time he apparently earned his basic license, night rating, instrument rating, multi engine rating and commercial rating. That is just wrong and should not be considered sufficient experience in any shape or form. In Canada you would need Hundred's (300-400) hours to accumulate all those ratings and then at least another 1,000 hours or so before you graduated to a 737 as FO.

If the Pilot was incapacitated how would you feel about having a FO with 98 total hours(or 154) in charge of getting you safely back to the ground? If you are good with that standard of training then fine - but I am not.

Over on the other forum someone who sounds very familiar with the 737 (possibly a Captain) is speculating the following:

"having belatedly recognized the need to cutout trim switches the
pilot either doesnt ask the copilot to trim ANU manually or the copilot
doesnt know how to operate manual trim (manual handle button must be depressed
before it will release)....relates to training and crew composition...200 hour
pilots dont belong in airline operations,pay to fly,SOP rote over airmanship etc etc"

It's quite possible the FO with that low hours had never operated the manual trim so didn't know they had to depress the manual handle button.

He gave up trying to see if it worked after 8 seconds. He may have tried it again (or the Pilot might have) - but there is nothing in the Text talking about that.
 
MildBlueYonder
Posts: 11
Joined: Sun Apr 08, 2018 6:30 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 2:52 am

PW100 wrote:
MildBlueYonder wrote:
dtw2hyd wrote:
If KC-46 already has a better implementation of MCAS, why can't Boeing just port it to MAX. This is not the right to keep counting beans.


Yeah, I’ve been wondering the same. Seems like the engineering and failure mode analyses for the KC-46 version of MCAS yielded all of the protections now being retrofitted into the MAX implementation. Kinda argues circumstantially in favor of external influence being applied to the latter.

Also, it just seems a bit circular and stupid that MCAS, which is a safety measure intended to catch pilots with poor training who decide to firewall the throttles rather than push the nose forward on the approach to stall, should itself be designed to rely entirely on stellar training to prevent catastrophe in the event of malfunction.


Well, the KC-46 probably did not have any implementation constraints with respect to training.

Apparently, one of the design constraints in the 737 MAX was that (pilot) conversion from NG to MAX should be very limited and no sim training.
I don't expect that USAF put such constraints on the KC-46.


Yeah, which argues that the desire to expedite conversion training led to safety compromises if you consider the KC-46 version to be the ideal implementation, although I guess the KC-46 doesn’t have a manual trim wheel to serve as the last line of defense insofar as Boeing’s failure mode analysis is concerned.
 
zoom321
Posts: 38
Joined: Sat Mar 09, 2019 3:05 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 2:57 am

dragon6172 wrote:
Aviation737 wrote:
So the question that I have is why were the crew of the previous Lion Air fight (the flight before JT610) were able to save the plane while the Ethiopian flight didn't? To me, both flights seem they were in similar conditions as both flight crews managed to turn off the stab trim switches according to my understanding.

Because they trimmed to a more normal 5.0 units of trim before turning it off.

Following the half baked AD post Lion crash caused ET to crash faster than Lion. Otherwise, they could have had a chance like the previous Lion flight.
 
ubeema
Posts: 361
Joined: Thu Aug 23, 2012 3:48 am

Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 3:03 am

Can anyone comment based on available data how the 6min ride was like for the passengers and remaining crew?
 
jchaase
Posts: 32
Joined: Thu Nov 04, 2010 5:21 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 3:07 am

anfromme wrote:
smartplane wrote:
Finn350 wrote:
Apparently STAB TRIM CUTOUT switch positions are not recorded by the DFDR, and so they cannot directly identify the position of the switches.

Not recorded, because MCAS, as well as the pilots, can change.

Likely MCAS will turn out to have three settings - OFF (procedure yet to be disclosed by Boeing), ON and BACKGROUND (what is currently described as OFF). In certain flight conditions, MCAS can be provoked from BACKGROUND to ON, even intruding in conditions where it shouldn't, like flaps extended and autopilot on.
Actually, I would say - based on what we have learnt in the past few weeks - that MCAS is on or off.
The chief point is - contrary to what you would have thought after that AD last year, using the cutout switches as per runaway trim procedure does not actually turn MCAS off. It just disables the actuator motors MCAS controls. Which means that if you flip the switches back on, MCAS might just be in the middle of one of its cycles and thus immediately start having an effect on trim again as the motor responds to input again.


This was one of my takeaways from reviewing the data from today - the FDR showed the trim commanded from MCAS, but no movement because the switches were off at that point.
 
many321
Posts: 282
Joined: Sat Mar 11, 2017 6:15 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 3:32 am

ubeema wrote:
Can anyone comment based on available data how the 6min ride was like for the passengers and remaining crew?


Good question. I'm also pondering that.
 
sadiqutp
Posts: 277
Joined: Thu Sep 08, 2016 5:05 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 3:42 am

B737900ER wrote:

I don’t think you understand aviation accidents. There is NEVER a single point of failure.


I am not one to nitpick, but tell that to the 737 pilots with infamous rudder hard over accidents

I want to confront this narrative of false equivalency of both machine and human sharing the same blame in this accident.

- It's now well know and hardly disputed that there are both a hardware failure (AOA failure), and design failure ( MCAS, Boeing never denied it and has announced a fix in the working)
- As for human factor, it is all speculations and conclusions based on no evidence. Let's put experienced pilots on a Max simulator, and expose them to the same circumstances, faults, and workload with same required training by Boeing and see what happens.. They might save the flight, they might not. Until then, I would be extremely careful to muddy the water with a narrative that confirms to my bias.(Do max simulators have the MCAS simulation?)
Last edited by sadiqutp on Fri Apr 05, 2019 3:44 am, edited 1 time in total.
 
glideslope900
Posts: 119
Joined: Sun Feb 24, 2019 5:27 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 3:44 am

spacecadet wrote:
remcor wrote:
spacecadet wrote:

Speed brakes, flaps, landing gear...

Not saying they had a way out of the situation, but as for this specific question, yes, there are ways to reduce airspeed in an airliner besides just reducing throttle and pitching up. Otherwise no airliner could ever land.


Still, all would cause the nose to pitch down.


Flaps change the wing chord line and actually cause it to "pitch up" (the fuselage may not, but the wing does) until speed is reduced enough for it to pitch down. If flying manually, you actually need to push the nose down to maintain altitude when deploying flaps - otherwise you will balloon. At the speeds they thought they were at, deploying flaps would not be something you'd normally want to do. But in an emergency situation where the checklists aren't working and you're improvising, all options are on the table.

Anyway, it depends on what the goal is at any given time. From the sound of it, they had a 2000fpm ascent going when they turned the trim system back on. I'm just unclear on what they were actually trying to do - it seems like they thought they were overspeeding, so I don't know how retrimming is going to help that. I guess they must have thought the problem was really the engines or airspeed indicators, and they wanted even more of a pitch up. Clearly, whether they should have known it or not, switching the trim system back on was not the right thing to do because it led to an accident. They weren't following a checklist or procedure at that point. I'm sure it was a confusing situation, but they seemed to be improvising at that point and just got it wrong.

Of course the MCAS system is at least partly to blame - I don't think that's a question anymore - but based on this initial report, there are definitely still questions about what the pilots were doing and why. As someone else said above, almost no accident has a single cause.


I was under the impression that they re engaged the trim because they could still not control the aircraft. They had significant aft pressure (holding the column back takes strength and is tiring) and wanted the stab trim back so they can trim some of that pressure out. All this did was re activate MCAS. Am I right?
 
mzlin
Posts: 103
Joined: Sat Mar 31, 2012 6:32 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 3:54 am

glideslope900 wrote:
spacecadet wrote:
remcor wrote:

Still, all would cause the nose to pitch down.


Flaps change the wing chord line and actually cause it to "pitch up" (the fuselage may not, but the wing does) until speed is reduced enough for it to pitch down. If flying manually, you actually need to push the nose down to maintain altitude when deploying flaps - otherwise you will balloon. At the speeds they thought they were at, deploying flaps would not be something you'd normally want to do. But in an emergency situation where the checklists aren't working and you're improvising, all options are on the table.

Anyway, it depends on what the goal is at any given time. From the sound of it, they had a 2000fpm ascent going when they turned the trim system back on. I'm just unclear on what they were actually trying to do - it seems like they thought they were overspeeding, so I don't know how retrimming is going to help that. I guess they must have thought the problem was really the engines or airspeed indicators, and they wanted even more of a pitch up. Clearly, whether they should have known it or not, switching the trim system back on was not the right thing to do because it led to an accident. They weren't following a checklist or procedure at that point. I'm sure it was a confusing situation, but they seemed to be improvising at that point and just got it wrong.

Of course the MCAS system is at least partly to blame - I don't think that's a question anymore - but based on this initial report, there are definitely still questions about what the pilots were doing and why. As someone else said above, almost no accident has a single cause.


I was under the impression that they re engaged the trim because they could still not control the aircraft. They had significant aft pressure (holding the column back takes strength and is tiring) and wanted the stab trim back so they can trim some of that pressure out. All this did was re activate MCAS. Am I right?


Mostly but not completely right, because MCAS was not "all this did." It did reactivate MCAS, but it ALSO first allowed them to input a nose-up trim via the trim tabs on the control column. And they could have continued to counter MCAS with trim tab inputs, as the captain had done successfully 20 times in the Lion Air accident flight prior to handing off control to the FO.
Last edited by mzlin on Fri Apr 05, 2019 3:57 am, edited 1 time in total.
 
Chemist
Posts: 519
Joined: Tue Oct 20, 2015 4:46 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 3:56 am

Amexair wrote:
Chemist wrote:
Interested wrote:




You realize you need pitch to control the speed of the aircraft when IAS is unreliable. In this case, they were fighting to keep the aircraft pitch stable which means there goes any control you have over speed. Reducing thrust will result in further nose-down pitch.


I'm not saying it would be easy, and Boeing's system is clearly at fault here.
But when they couldn't continue flying, a substantial power reduction could have kept airspeed at a reasonable range, which would have helped the manual (wheel) trim to be easier to operate.
Once too fast, then power would slow them down but not quickly. And of course flaps and speedbrakes, not sure the minimums on those, but they were already overspeed anyway so test pilots.
 
glideslope900
Posts: 119
Joined: Sun Feb 24, 2019 5:27 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 3:57 am

mzlin wrote:
glideslope900 wrote:
spacecadet wrote:

Flaps change the wing chord line and actually cause it to "pitch up" (the fuselage may not, but the wing does) until speed is reduced enough for it to pitch down. If flying manually, you actually need to push the nose down to maintain altitude when deploying flaps - otherwise you will balloon. At the speeds they thought they were at, deploying flaps would not be something you'd normally want to do. But in an emergency situation where the checklists aren't working and you're improvising, all options are on the table.

Anyway, it depends on what the goal is at any given time. From the sound of it, they had a 2000fpm ascent going when they turned the trim system back on. I'm just unclear on what they were actually trying to do - it seems like they thought they were overspeeding, so I don't know how retrimming is going to help that. I guess they must have thought the problem was really the engines or airspeed indicators, and they wanted even more of a pitch up. Clearly, whether they should have known it or not, switching the trim system back on was not the right thing to do because it led to an accident. They weren't following a checklist or procedure at that point. I'm sure it was a confusing situation, but they seemed to be improvising at that point and just got it wrong.

Of course the MCAS system is at least partly to blame - I don't think that's a question anymore - but based on this initial report, there are definitely still questions about what the pilots were doing and why. As someone else said above, almost no accident has a single cause.


I was under the impression that they re engaged the trim because they could still not control the aircraft. They had significant aft pressure (holding the column back takes strength and is tiring) and wanted the stab trim back so they can trim some of that pressure out. All this did was re activate MCAS. Am I right?


Not right, because MCAS was not "all this did." It did reactivate MCAS, but it ALSO first allowed them to input a nose-up trim via the trim tabs on the control column. And they could have continued to counter MCAS with trim tab inputs, as the captain had done successfully 20 times in the Lion Air accident flight prior to handing off control to the FO.



So then the question is why the hell were they not trimming nose up if the pilot trim overrides MCAS???

That seems like a crucial action at this point which they did not do for some reason. Most likely they were overwhelmed and just pulling the column back as hard as they could forgetting about the trim switches possibly?
 
Armodeen
Posts: 1164
Joined: Wed Aug 28, 2013 10:17 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 4:39 am

Planetalk wrote:
Also worth noting, given how he was slandered on here, that the FO seems to have performed well throughout and it was he that called out 'Trim cutout'. One poster who had said some particularly nasty things about him on another popular flying forum has already issued a Mea Culpa and acknowledged he performed admirably.


A lot more crow needs to be eaten by some members here who casted aspersions on him based on some arbitrary numbers. RIP to them both, they fought it to the end.
 
sciing
Posts: 144
Joined: Tue Feb 03, 2015 9:54 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 4:53 am

morrisond wrote:
B737900ER wrote:
Interested wrote:

Yep - those pilots seemed to follow their procedures as well as anyone could have expected

Plane designers are supposed to design planes that average pilots can fly safely

These guys performed at least average

If they hadn't they would be getting absolutely hammered on here

The Boeing apologists have actually seriously struggled to find things to criticise


I don’t think you understand aviation accidents. There is NEVER a single point of failure. There’s probably 11 different things that went wrong on that flight. Once again is a faulty flight control system to blame? Yes. Are pilot actions to blame? Yes. If it comes to light that some fod caused damage, is that to blame? Yes. Is having a massively inexperienced pilot at the controls of an aircraft nobody has been well trained on during an emergency situation to blame? Yes. As well as a dozen other factors.

What happened was tragic. Pointing fingers at the crew or Boeing or whoever as if one action and one action only is to blame is naive and pointless. The industry was built on leading from these kinds of incidents. We’ll learn from it and make things safer. This is in no way the last plane crash. There will be others. But they will happen less frequently as we build off the lessons learned here.


Great post - I agree 100% It was a combination of many factors. Boeing and Pilots.

BTW - The FO of that plane had less hours than I do (he was at 98 hours(or 154 the report is a little unclear) - I got to about 110 total before stopping 10 years ago)before he was made a FO of an 737. If you don't think I know what I'm talking about - well someone with less hours (or slightly more) was made a FO of a 737.

In that time he apparently earned his basic license, night rating, instrument rating, multi engine rating and commercial rating. That is just wrong and should not be considered sufficient experience in any shape or form. In Canada you would need Hundred's (300-400) hours to accumulate all those ratings and then at least another 1,000 hours or so before you graduated to a 737 as FO.

If the Pilot was incapacitated how would you feel about having a FO with 98 total hours(or 154) in charge of getting you safely back to the ground? If you are good with that standard of training then fine - but I am not.

Over on the other forum someone who sounds very familiar with the 737 (possibly a Captain) is speculating the following:

"having belatedly recognized the need to cutout trim switches the
pilot either doesnt ask the copilot to trim ANU manually or the copilot
doesnt know how to operate manual trim (manual handle button must be depressed
before it will release)....relates to training and crew composition...200 hour
pilots dont belong in airline operations,pay to fly,SOP rote over airmanship etc etc"

It's quite possible the FO with that low hours had never operated the manual trim so didn't know they had to depress the manual handle button.

He gave up trying to see if it worked after 8 seconds. He may have tried it again (or the Pilot might have) - but there is nothing in the Text talking about that.


Clearly a comment from a part of the world where on the job training is the poor standard and a suitable word for „Ausbildung“ even do not exist.
Please tell me how many 1000h pilots have ever used manual trims. Safety and systems is nothing you should learn by doing!
 
zhetenyi1973
Posts: 5
Joined: Thu Apr 04, 2019 7:08 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 5:15 am

Since MCAS is always on why we do not see more MCAS trim commands for more than 2 minutes?
 
MSPNWA
Posts: 3243
Joined: Thu Apr 23, 2009 2:48 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 5:19 am

Armodeen wrote:
they fought it to the end.


Effort isn't what makes a pilot. We don't place them in the pointy end because they can try. We place them there because they can do.
 
Elshad
Posts: 82
Joined: Wed May 23, 2018 8:24 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 5:25 am

acechip wrote:
How many examples in commercial aviation exist where the plane has a control system to correct an inherently unstable aerodynamic situation (by design) ?

Don’t know about commercial but I think a lot of fighter aircraft are like that e.g. Eurofighter Typhoon. But they are all FBW.

The problem with the 737 MAX is that it’s an old non-FBW mechanical plane with a pathy control system overlaid on top. Very messy.
 
VV
Posts: 704
Joined: Sat Feb 13, 2016 1:03 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 5:28 am

Interested wrote:
VV wrote:
Reading the comments above I became confused.

Were the switches flipped off or were they on?

Is flipping the switch back on part of the procedure?


Me too

I've been told for two or three weeks all they needed to do was flick a switch and fly the plane with normal stick and rudder control like all the US pilots would do

I've read the report. But after they flicked the switch it reads like they still had no control on the plane?


I am not a pilot, haven't read the preliminary report and will wait until the final one is released.

However, I am quite confused by some press articles that reported the crew repeatedly performed the procedure. How was it possible if the switches were flipped OFF already?

I guess the trim wheels should provide the pilots with manual control of the horizontal stabilizer once the switch is OFF.

Was there something else that has not been reported by the press?
 
Etheereal
Posts: 300
Joined: Tue Nov 29, 2016 11:44 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 5:41 am

sadiqutp wrote:
B737900ER wrote:

I don’t think you understand aviation accidents. There is NEVER a single point of failure.


I am not one to nitpick, but tell that to the 737 pilots with infamous rudder hard over accidents

I want to confront this narrative of false equivalency of both machine and human sharing the same blame in this accident.

- It's now well know and hardly disputed that there are both a hardware failure (AOA failure), and design failure ( MCAS, Boeing never denied it and has announced a fix in the working)
- As for human factor, it is all speculations and conclusions based on no evidence. Let's put experienced pilots on a Max simulator, and expose them to the same circumstances, faults, and workload with same required training by Boeing and see what happens.. They might save the flight, they might not. Until then, I would be extremely careful to muddy the water with a narrative that confirms to my bias.(Do max simulators have the MCAS simulation?)

Of the 4 incidents regarding the rudder, only 1 didnt end with a crash, because the pilot did a counter intuitive maneouver which managed to get the plane's rudder un-stuck while holding on air.

So the failures in the previous 3 crashes were the servo freezing/getting stuck + the pilots' "errouneous reaction due extreme bank angle".
Last edited by Etheereal on Fri Apr 05, 2019 5:41 am, edited 1 time in total.
JetBuddy wrote:
"737 slides off the runway" is the new "Florida man"..

:lol:
 
HaulSudson
Posts: 61
Joined: Tue Feb 12, 2019 6:02 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 5:41 am

jchaase wrote:
anfromme wrote:
smartplane wrote:
Not recorded, because MCAS, as well as the pilots, can change.

Likely MCAS will turn out to have three settings - OFF (procedure yet to be disclosed by Boeing), ON and BACKGROUND (what is currently described as OFF). In certain flight conditions, MCAS can be provoked from BACKGROUND to ON, even intruding in conditions where it shouldn't, like flaps extended and autopilot on.
Actually, I would say - based on what we have learnt in the past few weeks - that MCAS is on or off.
The chief point is - contrary to what you would have thought after that AD last year, using the cutout switches as per runaway trim procedure does not actually turn MCAS off. It just disables the actuator motors MCAS controls. Which means that if you flip the switches back on, MCAS might just be in the middle of one of its cycles and thus immediately start having an effect on trim again as the motor responds to input again.


This was one of my takeaways from reviewing the data from today - the FDR showed the trim commanded from MCAS, but no movement because the switches were off at that point.


There is no evidence those switches were turned back on by the pilots. Or by one of them.


The MCAS system seems to have an undisclosed procedure in which the cutout switches are bypassed and pilots are not in control anymore.

Also note the Boeing press release stating that in future they want the pilots to be able to always override the MCAS machine in manual mode.
https://boeing.mediaroom.com/2019-04-04 ... ary-Report

This suggests that at present, there are situations that cannot be rescued by the crew in manual mode, since the software overrides and takes over control.

It could also explain the previously not understood strong dive at the end of both crashes. Not blowback, MCAS in exceptional mode.
Last edited by HaulSudson on Fri Apr 05, 2019 5:45 am, edited 1 time in total.
 
tribird1011
Posts: 214
Joined: Mon Mar 14, 2005 10:08 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 05, 2019 5:42 am

morrisond wrote:

Great post - I agree 100% It was a combination of many factors. Boeing and Pilots.

BTW - The FO of that plane had less hours than I do (he was at 98 hours(or 154 the report is a little unclear) - I got to about 110 total before stopping 10 years ago)before he was made a FO of an 737. If you don't think I know what I'm talking about - well someone with less hours (or slightly more) was made a FO of a 737.

In that time he apparently earned his basic license, night rating, instrument rating, multi engine rating and commercial rating. That is just wrong and should not be considered sufficient experience in any shape or form. In Canada you would need Hundred's (300-400) hours to accumulate all those ratings and then at least another 1,000 hours or so before you graduated to a 737 as FO.

If the Pilot was incapacitated how would you feel about having a FO with 98 total hours(or 154) in charge of getting you safely back to the ground? If you are good with that standard of training then fine - but I am not.

Over on the other forum someone who sounds very familiar with the 737 (possibly a Captain) is speculating the following:

"having belatedly recognized the need to cutout trim switches the
pilot either doesnt ask the copilot to trim ANU manually or the copilot
doesnt know how to operate manual trim (manual handle button must be depressed
before it will release)....relates to training and crew composition...200 hour
pilots dont belong in airline operations,pay to fly,SOP rote over airmanship etc etc"

It's quite possible the FO with that low hours had never operated the manual trim so didn't know they had to depress the manual handle button.

He gave up trying to see if it worked after 8 seconds. He may have tried it again (or the Pilot might have) - but there is nothing in the Text talking about that.


Need to highlight that particular line...

In Canada, I obtained my Commercial licence at 201.6 hours. That included Night rating and Group 1 Multi-Engine and IFR Ratings.
Believe it or not, in Canada you can write the IATRA exam (essentially ATPL knowledge) with 250 hours. IF you get a type rating on (let's say a 737) you too can ride right seat on that airplane with 250 hours. Now, the way the industry is set up here, the airlines won't hire you with that low time strictly for insurance purposes... as per TC, it's totally legal!!

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