F9Animal
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:00 pm

Pluto707 wrote:
Another (stupid ?) question: Is the NTSB really entitled to harm Boeing ?


The NTSB isnt out to harm anybody. They are out to prevent people from being harmed. They are simply investigating, and making recommendations. If they find something that could harm Boeing, then I think that is all in Boeings lap.
I Am A Different Animal!!
 
Bobloblaw
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:02 pm

GEUltraFan9XGTF wrote:
If it is determined that broken AOA sensors contributed to faulty activation of MCAS in both scenarios, is there a chance that some preflight checklist item, maybe as something as innocent as opening and closing the forward cargo door, is adding to the likelihood that the AOA sensor is being damaged?

Correct. I think it might be a sensor sending bad data to MCAS but I’m not an expert unlike many others.
 
Curiousflyer
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:02 pm

Trin wrote:
trpmb6 wrote:
N1KE wrote:
CAA now following others and grounding the MAX. Sad day for aviation and for Boeing. Hopefully a fix will be found soon and flying can restart. How long before we have s total grounding?


A fix? A fix for what? We don't even know what caused the Ethiopian crash at this point. Just educated guesses. For all we know it could be a terrorist act that led to elevator control issues.


People who like to play devils advocates also denied that pilot error could be responsible for AF447......before it was revealed that that's what it was. As I said before - the pedantic amongst us will argue that "flight control issues" could reference anything that a person individually WANTS it to, but the fact remains that if this incident was more strongly pointing towards 'terrorism' than an issue with the airframe itself, we would probably already know - and rather than news stories of nations grounding their MAX fleets, we would be reading about nations elevating their terror levels. A lot more is always known much earlier in private in these cases than is released to the public - but we CAN construe what is known privately from the (necessarily) public reactions of companies and nations to that private information.


Pilot error was only one component, disorientation in the middle of the night, in a storm in the middle of the ocean. Other causes were that the Pitot tubes were defective, the issue was known and Airbus and Air France had not replaced them fast enough in order to save money, nor had they sufficiently trained the crews. As often there is not a single cause for a crash.
 
Z88
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:03 pm

I'm a first-time poster but a very long time lurker (for many years). This forum is one of the best kept secrets on the internet and is my "go-to" resource whenever anything happens in the aviation world that I want to learn more about.

As an engineer (unrelated to aviation) one of the first things I think when something like this happens is "what went wrong and what changes can prevent it from happening again". Maybe that isn't the correct first reaction. Maybe I should take a moment to think of the 157 souls lost and the impact their loss will have on their families and loved ones. Grief though, however valuable it is to our emotional health, doesn't solve the problem of understanding and preventing the mechanisms behind that loss.

The reason I'm breaking silence today is to complement you all on the discussions you have here. It is obvious that for some of you emotions are running high and some are being borderline insulting and dismissive to each other. Please understand that as an aviation outsider being able to read multiple sides of an argument each being violently defended provides valuable insight. It helps me to understand how people of differing opinions view the issue and therefore helps me come to my own conclusions instead of accepting simply whatever those "in authority" tell me.

In closing, thanks to all of you for what you make this forum, and despite your differences in opinion please remember the souls lost and the person on the other end of the messages you are sending.
 
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trpmb6
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:03 pm

Trin wrote:
trpmb6 wrote:
Trin wrote:

One of the most pointed and impressively simple questions I've seen so far on here. My thoughts EXACTLY. It is high time that we got some answers as to the basic handling characteristics of this airframe, and what was discovered ruing testing/modeling that made the need for MCAS (or, if you are being pedantic - 'enhanced MCAS' on the MAX) to be implemented/allowed such aggressive and exclusive/recurring control of certain situations.



The Max is not inherently unstable (like some fighter planes may be to achieve better maneuverability as someone upthread quipped). It will fly straight and level under normal conditions just like the NG will. What differs is the behavior as you approach edge of the flight envelope. The closer to stall you get in a max the harder it is to recover in relation to the NG* Note, this does not mean that you cannot recover from that portion of the envelope, only that it does not behave, or feel like the NG does. To help assist, and to maintain type ratings, the MCAS was introduced to adjust horizontal stab trim automatically. The result was that as you approach these edges of the flight envelope you would perceive virtually no difference in aircraft behavior between the Max and the NG.


So what happened in testing/simulation when they programmed invalid AOA data into the MCAS during its active phase?


Not privy to that information, and even if I was that is certainly something that would not be getting posted here for legal reasons.
 
georgiaame
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:03 pm

This armchair expert has just read that the plane was reported to have smoke coming out of the tail and clothing and papers flying out the back moments before the crash. Sounds to me like the APU in the tail blew, and took out a chunk of the luggage compartment. Planes don't fly well with holes in their tails. As for terrorism, well, that would be politically incorrect to publish, but I'm sure someone is looking into that possibility. IMHO, you ground ALL of those planes, immediately, until you understand fully why two of the same machines fell out of the skies, both early into takeoff. In the words of Auric Goldfinger many years ago, "Once is happenstance. Twice is circumstance. Three times it is enemy action." There should not be a third incident, and this does smell a bit like the early Comets!
"Trust, but verify!" An old Russian proverb, quoted often by a modern American hero
 
vfw614
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:07 pm

ranold76 wrote:
Mortyman wrote:
So is it only US airlines that has not grounded it's Max's now ?

https://flightaware.com/live/aircrafttype/B38M
U.S., Canada and many others.... for now..


"Many others"? 35 airlines (and counting) have grounded their MAXs. 13 have not or have not been grounded, 5 of them US/Canadian airlines (the status of 5 MAXs operated by 3 small airlines is currently unknown).

So outside North Americs, 81 per cent of operators have grounded their MAXs. Of those very few that have not, some are effectively unable to continue operating them because of airspace restrictions across Europe (LOT, Smartwings) so I expect them to technically ground soon just for the sake of avoiding bad PR.
 
JAAlbert
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:08 pm

frmrCapCadet wrote:
A number of assumptions in this thread are simply wrong.

Boeing did not do the MAX because they were short of money. They in fact wanted to do an all new plane - airlines would not wait after the 320neo came out.


I recall reading back at the time that Boeing did approach airlines re: a clean sheet design, but the airlines didn't want to wait that long. Boeing did the MAX as a result. I'm sure money was an issue as well - it always is. Does anyone else recall this?

It is surprising to me that Boeing is being condemned for shoddy practices, cutting corners, putting profits first, etc, etc, before any of us have seen a single data point from the investigative authorities. I see the MCAS system as a rational response to the larger, more forward engines -- it seems the failure to understand how the system would work when incorrect data was fed into it (if that occurred) is an enormous flaw in Boeing's design practices, that could expose the company (and if found to be true should expose the company) to significant liability. But I do not see any evidence (thus far) that Boeing intentionally installed a system knowing it was defective or deficient - and somehow hoping nobody would figure it out.

The ET crash is a tragedy -- and a mystery. None of the scenarios put forth so far clearly explain the situation -- why would MCAS be operational - if it was - at 1000 ft? Why were flaps retracted -- if they were -- when the plane was struggling with altitude? What is the significance of the 777 pilots who heard the ET Max pilots reporting an unreliable airspeed issue? (note, it doesn't appear that a 777 was at ADD awaiting take off at the time of the incident). Airline crashes are often a cascade of small events, mechanical or human error or both, that when strung together cause a catastrophe. It seems this will be the case here given the conflicting (and almost nonexistent) facts.

Now, if EASA calls for a ban this afternoon, I'd have some assurance that they have reviewed some data and found a link between the two crashes. The FAA will do the same if they find a link. I am sure everyone - Boeing execs included - want the answers yesterday.
 
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trpmb6
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:10 pm

B777LRF wrote:
Cdydatzigs wrote:
Other than the fact the fuselage of a MAX is shaped like a plane from 1958, all of the other components of the aircraft are state-of-the art.


The 737 MAX overhead panel and centre pedestal just called, you owe them a new keyboard. Same goes for much of the structure. Seriously, it has a new panel, engines, electronics, nose-gear and wings. Hydraulic, electric and pneumatics are more or less the samen, and it's all bolted onto 1950s era structure.

It is the aviation epitome of applying ever thicker coats of lipstick to a pig.


Well not entirely true either. A lot of the structure may look like 1950's era structure but it has been reevaluated and updated as needed. Might even be on the same drawing in some cases, maybe as simple as a skin gauge change.
 
osiris30
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:12 pm

Trin wrote:
estorilm wrote:
kalvado wrote:

I was basically asking, if I disabled MCAS and approached a stall at high AoA in a 737NG and a 737MAX, what would the differences be? I'm asking because clearly Boeing had enough data on some rather unfriendly discoveries during modeling / testing to justify the implementation of MCAS. I just want to know what exactly they found, and how severe it is.


One of the most pointed and impressively simple questions I've seen so far on here. My thoughts EXACTLY. It is high time that we got some answers as to the basic handling characteristics of this airframe, and what was discovered ruing testing/modeling that made the need for MCAS (or, if you are being pedantic - 'enhanced MCAS' on the MAX) to be implemented/allowed such aggressive and exclusive/recurring control of certain situations.


Geeze guys. You have your answer! The fact MCAS is there tells you as much. In high AOA high thrust situations the engines are forward enough of the cog to exacerbate the AOA situation. It is a situation that can be perfect cancelled with corrective actions on the flight controls but hands off the plane will flip itself over in theory.

The same may be true on the NEO with all protection controls disabled. Airbus's FBW system provides a lot of aircraft "feel" and behaviour enhancements for the pilots too. Airbus has had high alpha protection for decades now. This is, in effect the same thing.

The one thing I will agree with is MCAS should have a lower authority limit. Boeing agrees as well and is working on the software update already. As to why it isn't out yet, I would simply say that aircraft software takes FOREVER to validate due to regulatory oversight and requirements.

Boeing was (as I understand it) originally targeting this month for the change but it has apparently slipped a bit. Embedded QA is hard. Embedded QA in a highly regulated industry is infinitely harder (one of our old posters Astuteman had horror stories from back in the day as it related to software on nuclear subs).

And before anyone sounds off about "Boeing knew this or that":

1). Mcas if working properly is a perfectly acceptable solution to the CoG issue. Lots of frames use software compensation these days. It is not "new" and is totally acceptable.
2) sometimes when you design a system or certify one things happen that no one foresaw or could reasonably foresee. There is an old saying and hindsight being 20/20. This applies in all directions. Things are plainly obvious AFTER they happen but how many times have all of us done something that had an outcome we did not expect until we experienced that outcome. It happens. Welcome to humans.
3) there is still no evidence mcas had anything to do with this accident
4) ET's CEO just said the pilot had MCAS training recently.

I still think something very unrelated happened between the two crashes and I still maintain the grounding is in response to media and social media pressure and not facts. Others can disagree but again this isn't really the thread for grounding talk anyway (there is one elsewhere on this site).

I want to get the data from this crash. There could be any number of things at play from basic pilot error to mechanical failure to systems failure (mcas), etc. ANY of those can be made to fit the circumstances of this crash. And we can safely guess that some COMBINATION of those apply to Lion Air. Yet all anyone wants to talk about is MCAS and that is likely leading people down a very wrong path (anyone who has studied any aviation accident knows it is rarely as simple as "my first guess was right and the sole contributer")
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
SimonL
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:13 pm

https://edition.cnn.com/world/live-news ... afb8d5b536

From the CEO of Ethiopian:
The pilots of the doomed Ethiopian Airlines flight told air traffic control they were having “flight control problems” before the crash, airline CEO Tewolde GebreMariam told CNN’s Richard Quest Tuesday.

That suggests the plane was not responding to pilots’ inputs and they were losing control of the aircraft, Quest explains.

GebreMariam said the flight data recorders “will be sent overseas,” rather than being read in Ethiopia, which does not have the technical capability to do it. He did not say where, specifically, they would be read.

Pilots were aware of airworthiness directive issued after the Lion Air crash in October and had had additional training, he said.



So the similarities with the Lion Air crash are definitely there and the pilots was aware of the issues with MCAS and how to handle them. My personal opinion is that grounding the plane is the right thing to do at this point since there is a possibility that the plane can crash due to MCAS issues and that the pilots aren't able to control the aircraft despite having knowledge about it and additional training to handle it. So the worst case scenario is that the plane have a single point of failure that renders the plane uncontrollable. Im not saying its the case but imo since we DON'T know that it ISNT'T the case the plane should be grounded until we know.
 
buzzard302
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:19 pm

Ground an airplane is a big deal. Most likely someone knows something that is not public. These decisions don't come lightly. If they were to release a public comment saying there was a design flaw related to these accidents, it would cause more problems than they already have. The media is already going nuts with it and they don't know anything more than this forum most likely.
 
Flightsimboy
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:22 pm

F9Animal wrote:
Pluto707 wrote:
Another (stupid ?) question: Is the NTSB really entitled to harm Boeing ?


The NTSB isnt out to harm anybody. They are out to prevent people from being harmed. They are simply investigating, and making recommendations. If they find something that could harm Boeing, then I think that is all in Boeings lap.


The politically correct term is "Goofy" not stupid. The armchair NTSB inspectors on this site provide answers to goofy questions. You'll have to scroll or pull up my posts to see what I am talking about. Okay back to the discussion now.
LAX772LR - "Answer to goofy question:" in response to my question about the B737-MAX8 being grounded. 48 hours later all B737-MAX8 grounded worldwide. Go figure!!
 
osiris30
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:22 pm

buzzard302 wrote:
Ground an airplane is a big deal. Most likely someone knows something that is not public. These decisions don't come lightly. If they were to release a public comment saying there was a design flaw related to these accidents, it would cause more problems than they already have. The media is already going nuts with it and they don't know anything more than this forum most likely.


If the UKCAA knows data that is not public but available the FAA would follow suit or risk extreme liability. There is no way the CAA knows anything the FAA doesn't as it is the NTSB helping the investigation for the UK agency

You are making an assumption. No one has seen the FDR data yet or CVR. As I understand they are enroute to a lab as I write this.
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
ikramerica
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:39 pm

vfw614 wrote:
ranold76 wrote:
Mortyman wrote:
So is it only US airlines that has not grounded it's Max's now ?

https://flightaware.com/live/aircrafttype/B38M
U.S., Canada and many others.... for now..


"Many others"? 35 airlines (and counting) have grounded their MAXs. 13 have not or have not been grounded, 5 of them US/Canadian airlines (the status of 5 MAXs operated by 3 small airlines is currently unknown).

So outside North Americs, 81 per cent of operators have grounded their MAXs. Of those very few that have not, some are effectively unable to continue operating them because of airspace restrictions across Europe (LOT, Smartwings) so I expect them to technically ground soon just for the sake of avoiding bad PR.

Simply not true.

China won't permit them to fly domestically. The airlines aren't really free to make their own decisions. They have been grounded, the airlines didn't "ground" them. And that's a huge chunk of the number of airlines.

A look at the 767 accident in Houston and the latest information, it looks like the pilots were fighting a perceived uncommanded upward trajectory at full thrust, and then crashed it into the ground. We have no absolute cause yet. All of them should be grounded around the world...
Of all the things to worry about... the Wookie has no pants.
 
slamcannon
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:39 pm

buzzard302 wrote:
Ground an airplane is a big deal. Most likely someone knows something that is not public. These decisions don't come lightly. If they were to release a public comment saying there was a design flaw related to these accidents, it would cause more problems than they already have. The media is already going nuts with it and they don't know anything more than this forum most likely.


It's very possible they could have some inside preliminary info on the matter. I've been thinking about that every time another airline grounds the MAX.
 
ELBOB
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:43 pm

osiris30 wrote:
1). Mcas if working properly is a perfectly acceptable solution to the CoG issue. Lots of frames use software compensation these days. It is not "new" and is totally acceptable.


How is ramming the nose down every 10 seconds, WITHOUT ANNUNCIATION OR INDICATION, an acceptable solution? An FBW aircraft would be able to progressively dampen the nose-up tendency, though no FBW airliner is so poorly designed to require that because no FBW airliner has a grandfathered 1966 undercarriage design that puts the engines so far ahead of the wing.

2) sometimes when you design a system or certify one things happen that no one foresaw or could reasonably foresee. There is an old saying and hindsight being 20/20. This applies in all directions. Things are plainly obvious AFTER they happen but how many times have all of us done something that had an outcome we did not expect until we experienced that outcome. It happens. Welcome to humans.


Yes you find things after certification when the impetus is on pushing it through the test phase as fast as possible. Why aren't line airline crews involved in certification flight testing? Why isn't it deemed necessary to operate a new type on scheduled routes for a period of time without passengers and with normal line maintenance? Because $$$.
Last edited by ELBOB on Tue Mar 12, 2019 4:49 pm, edited 2 times in total.
 
ikramerica
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:46 pm

GEUltraFan9XGTF wrote:
If it is determined that broken AOA sensors contributed to faulty activation of MCAS in both scenarios, is there a chance that some preflight checklist item, maybe as something as innocent as opening and closing the forward cargo door, is adding to the likelihood that the AOA sensor is being damaged?

In the Lion crash thread, I got the impression that you can calibrate the installation of the AoA but they don't work correctly until you reach speed, so checking them on the ground isn't always going to be simple without the aircraft moving.

I have a question though: can they be checked by performing an intentional aborted take-off run? Is approaching the takeoff speed sufficient to confirm that the AoA sensors are reading correctly? I ask because even though US based mechanics have said that they would not dispatch the Lion aircraft without a flight test after so many repeated issues, testing it might be just as dangerous as making a flight (although only for a crew, not a crew+passengers).
Of all the things to worry about... the Wookie has no pants.
 
pune
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:50 pm

Trin wrote:

<snipped>

People who like to play devils advocates also denied that pilot error could be responsible for AF447......before it was revealed that that's what it was. As I said before - the pedantic amongst us will argue that "flight control issues" could reference anything that a person individually WANTS it to, but the fact remains that if this incident was more strongly pointing towards 'terrorism' than an issue with the airframe itself, we would probably already know - and rather than news stories of nations grounding their MAX fleets, we would be reading about nations elevating their terror levels. A lot more is always known much earlier in private in these cases than is released to the public - but we CAN construe what is known privately from the (necessarily) public reactions of companies and nations to that private information.


Completely agree with the above statement. In such situations I guess airlines management ask their peers from both the industry and other airlines insiders and then take a call. There would be lot of pressure on the Ethopian Airlines management to do justice as well as have tact . We will have to see what happens. The best would be to have whatever evidence they can share in the public domain so all and any rumor-mongering squashes but may probably depend on the Ethopian airspace regulator and the airlines as to what and how much they reveal and what happens to Boeing after that.
 
747megatop
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:51 pm

osiris30 wrote:
Trin wrote:
estorilm wrote:



I still think something very unrelated happened between the two crashes and I still maintain the grounding is in response to media and social media pressure and not facts. Others can disagree but again this isn't really the thread for grounding talk anyway (there is one elsewhere on this site).



Regulatory agencies from multiple countries (UK, Singapore, Australia etc.) are way too mature and professionally to be grounding planes due to media and social media pressure. If that was the case almost every high profile incident/accident should result in a grounding.
 
afriwing
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:51 pm

osiris30 wrote:
buzzard302 wrote:
Ground an airplane is a big deal. Most likely someone knows something that is not public. These decisions don't come lightly. If they were to release a public comment saying there was a design flaw related to these accidents, it would cause more problems than they already have. The media is already going nuts with it and they don't know anything more than this forum most likely.


If the UKCAA knows data that is not public but available the FAA would follow suit or risk extreme liability. There is no way the CAA knows anything the FAA doesn't as it is the NTSB helping the investigation for the UK agency

You are making an assumption. No one has seen the FDR data yet or CVR. As I understand they are enroute to a lab as I write this.


Yeah at this stage I don't think the UKCAA knows any extra data (or any other authority for this matter). It's just that these national CAAs have no involvement with the MAX. Unlike the FAA and EASA who have certified the airplane. So I'm not surprised the FAA and EASA are late in their announcements.

As it happens, a little while ago ET ceo Mr Tewolde Gebremariam said the FDR & CVR "will be" taken to a facility abroad, which kind of hints that they are still in Addis Ababa till today. He also said they will probably not be analysed in the USA but rather at a European facility nearer to Ethiopia.
Afriwings
 
ikramerica
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:52 pm

ELBOB wrote:
osiris30 wrote:
1). Mcas if working properly is a perfectly acceptable solution to the CoG issue. Lots of frames use software compensation these days. It is not "new" and is totally acceptable.


How is ramming the nose down every 10 seconds an acceptable solution? An FBW aircraft would be able to progressively dampen the nose-up tendency, though no FBW airliner is so poorly designed to require that because no FBW airliner has a grandfathered 1966 undercarriage design that puts the engines so far ahead of the wing.

2) sometimes when you design a system or certify one things happen that no one foresaw or could reasonably foresee. There is an old saying and hindsight being 20/20. This applies in all directions. Things are plainly obvious AFTER they happen but how many times have all of us done something that had an outcome we did not expect until we experienced that outcome. It happens. Welcome to humans.


Yes you find things after certification when the impetus is on pushing it through the test phase as fast as possible. Why aren't line airline crews involved in certification flight testing?

1. If the pilots are continuing to try to pitch up more than is safe, the system is designed to push them down. If it was CONTINUOUS, then the pilots would fight it continuously and possibly cause a complete stall. But if the plane keeps pitching down to safety then letting go, the pilots are supposed to understand that they shouldn't try to fly straight up to 80,000 feet like a test pilot.

That said, there should be warning bells and indicators on the displays. MCAS as designed is too polite, or maybe passive aggressive.

2. bull. Please, please, please show me a mature platform where no safety critical corrections, ADs, whatever were made after certifications.

You can't flight test for 20 years to make sure that they didn't miss anything over the useful life of the aircraft. There is no complex piece of mechanical and or computer equipment that doesn't need some corrections after release to customers.
Of all the things to worry about... the Wookie has no pants.
 
osiris30
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:54 pm

ELBOB wrote:
osiris30 wrote:
1). Mcas if working properly is a perfectly acceptable solution to the CoG issue. Lots of frames use software compensation these days. It is not "new" and is totally acceptable.


How is ramming the nose down every 10 seconds, WITHOUT ANNUNCIATION OR INDICATION, an acceptable solution? An FBW aircraft would be able to progressively dampen the nose-up tendency, though no FBW airliner is so poorly designed to require that because no FBW airliner has a grandfathered 1966 undercarriage design that puts the engines so far ahead of the wing.


"ramming the nose down every 10 seconds" isn't what it remotely does. It will try to re-enage after being disengaged in 10 seconds unless disabled, so long as the condition exists. Otherwise it pushes the nose forward. The only 'ramming the nose down' that happened (ostensibly) in Lion Air was due to a faulty AOA sensor. If you think it just rams the nose forward you don't understand the system or its operation.

ELBOB wrote:
osiris30 wrote:
2) sometimes when you design a system or certify one things happen that no one foresaw or could reasonably foresee. There is an old saying and hindsight being 20/20. This applies in all directions. Things are plainly obvious AFTER they happen but how many times have all of us done something that had an outcome we did not expect until we experienced that outcome. It happens. Welcome to humans.


Yes you find things after certification when the impetus is on pushing it through the test phase as fast as possible. Why aren't line airline crews involved in certification flight testing? Why isn't it deemed necessary to operate a new type on scheduled routes for a period of time without passengers and with normal line maintenance? Because $$$.


Hey, if you want to pay 3x as much to fly around the world then by all means, let's certify the crap out of everything, let's even have A.net be part of certification. Hell let's get the politicians involved too! You may not like it but $$$ makes the world go around and STILL we have a ridiculously safe system. I suppose we could do it your way though and just cut off air travel due to insane expense from the vast majority of the world's population. It would certainly prevent more deaths in accidents (but would probably increase the number of wars we have due to lack of cultural and good exchange, but hey.. what's a few 10s of K people soldiers).
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
B777LRF
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:55 pm

GEUltraFan9XGTF wrote:
If it is determined that broken AOA sensors contributed to faulty activation of MCAS in both scenarios, is there a chance that some preflight checklist item, maybe as something as innocent as opening and closing the forward cargo door, is adding to the likelihood that the AOA sensor is being damaged?


The AoA vanes were repositioned with the NG and are well out the way of possible GSE contact.

Problem is that MCAS depends on a single source of input, either CPT or FO AoA sensor. The system cycles between CPT and FO for each flight, which is fine, but doesn't address the fundamental problem: the system depends on a single sensor.

Aircraft hit birds every single day, several times a day. One day a sufficiently big feathered friend may take out the active AoA sensor, potentially (as bird strikes mainly happen during t/o and landing phases) leading to MCAS induced nose-down trim at a very inopportune moment.

Not my idea of sound engineering.
Signature. You just read one.
 
barney captain
Posts: 2219
Joined: Tue Nov 06, 2001 5:47 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:55 pm

Z88 wrote:
I'm a first-time poster but a very long time lurker (for many years). This forum is one of the best kept secrets on the internet and is my "go-to" resource whenever anything happens in the aviation world that I want to learn more about.

As an engineer (unrelated to aviation) one of the first things I think when something like this happens is "what went wrong and what changes can prevent it from happening again". Maybe that isn't the correct first reaction. Maybe I should take a moment to think of the 157 souls lost and the impact their loss will have on their families and loved ones. Grief though, however valuable it is to our emotional health, doesn't solve the problem of understanding and preventing the mechanisms behind that loss.

The reason I'm breaking silence today is to complement you all on the discussions you have here. It is obvious that for some of you emotions are running high and some are being borderline insulting and dismissive to each other. Please understand that as an aviation outsider being able to read multiple sides of an argument each being violently defended provides valuable insight. It helps me to understand how people of differing opinions view the issue and therefore helps me come to my own conclusions instead of accepting simply whatever those "in authority" tell me.

In closing, thanks to all of you for what you make this forum, and despite your differences in opinion please remember the souls lost and the person on the other end of the messages you are sending.


Nicely stated and welcome to Anet! Your engineering background will provide valuable input to this forum. :)
Southeast Of Disorder
 
ikramerica
Posts: 14897
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:55 pm

afriwing wrote:
osiris30 wrote:
buzzard302 wrote:
Ground an airplane is a big deal. Most likely someone knows something that is not public. These decisions don't come lightly. If they were to release a public comment saying there was a design flaw related to these accidents, it would cause more problems than they already have. The media is already going nuts with it and they don't know anything more than this forum most likely.


If the UKCAA knows data that is not public but available the FAA would follow suit or risk extreme liability. There is no way the CAA knows anything the FAA doesn't as it is the NTSB helping the investigation for the UK agency

You are making an assumption. No one has seen the FDR data yet or CVR. As I understand they are enroute to a lab as I write this.


Yeah at this stage I don't think the UKCAA knows any extra data (or any other authority for this matter). It's just that these national CAAs have no involvement with the MAX. Unlike the FAA and EASA who have certified the airplane. So I'm not surprised the FAA and EASA are late in their announcements.

As it happens, a little while ago ET ceo Mr Tewolde Gebremariam said the FDR & CVR "will be" taken to a facility abroad, which kind of hints that they are still in Addis Ababa till today. He also said they will probably not be analysed in the USA but rather at a European facility nearer to Ethiopia.

It makes sense. They want it done in a similar time zone so they aren't constantly dealing with finding out info in the middle of the night, then having to deal with it during the work day. That schedule is untenable, because either you have two different groups working on it, or the single group gets no sleep.
Of all the things to worry about... the Wookie has no pants.
 
KarlB737
Posts: 2757
Joined: Sat Mar 20, 2004 9:51 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:56 pm

scbriml wrote:
KarlB737 wrote:
I believe that one point has been over looked here. 350 of the 737-8 MAX have been put into service. 348 are still flying OK as of today.


One point that seems to be overlooked by many people is that we have 300+ dead bodies on our hands.


OK, we all get that. What has happened is absolutely tragic. No one is discounting that. My only point that you quoted above was that until we get the facts we can't yet blame the aircraft. It may turn out to be a aircraft issue -- no one is ruling that out yet. What I believe would be a positive thing to do while we continue to wait for the facts is have some Southwest pilots share with this forum their experiences with their 738s and what they have learned since 34 have been delivered to them. Since Southwest has chosen not to ground the 738s I believe they have learned some detailed things about flying the 738s that I wish and hope they would share here. They obviously have the confidence in the 738 for specific reasons which may include some specific handling procedures that could be very positive in the midst of this heated discussion.

Southwest pilots please share your actual facts about your flying experience with your 738s. Thanks in advance.
 
cc2314
Posts: 127
Joined: Tue Jan 08, 2008 1:15 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:57 pm

Norwegian grounds Boeing 73 max

The Irish aviation authority temporarily suspends ops of all max variants into and out of Irish airspace.

I personally think this is the right thing to do,until at least they can understand what causes this most recent crash.
Deleted
 
ELBOB
Posts: 295
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:57 pm

ikramerica wrote:
You can't flight test for 20 years to make sure that they didn't miss anything over the useful life of the aircraft. There is no complex piece of mechanical and or computer equipment that doesn't need some corrections after release to customers.


Why not? That's the magnitude of deveopment period typical for military platforms. 15 years for the F-35, 17 for the V-22, 11 to 13 for the Typhoon.

Why are airliners, into which we entrust the lives of hundreds, tested for just over a year?
Last edited by ELBOB on Tue Mar 12, 2019 5:00 pm, edited 1 time in total.
 
PlanesNTrains
Posts: 9526
Joined: Tue Feb 01, 2005 4:19 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 4:59 pm

Trin wrote:
New quote by the Ethiopian Airlines CEO just now:

The pilots of the doomed Ethiopian Airlines flight told air traffic control they were having “flight control problems” before the crash, airline CEO Tewolde GebreMariam told CNN’s Richard Quest Tuesday.


Admittedly the pedantic can construe 'flight control problems' to encompass anything from problems with turbulence and spatial-D, to elevator control issues to a stuck flap. But it seems that this quote does little to discount a similar MCAS scenario to that of Lion Air.

So sad.


That is not new information - it’s been stated multiple times over the past few days.
-Dave


MAX’d out on MAX threads. If you are starting a thread, and it’s about the MAX - stop. There’s already a thread that covers it.
 
vfw614
Posts: 3795
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:06 pm

ikramerica wrote:
vfw614 wrote:
ranold76 wrote:
https://flightaware.com/live/aircrafttype/B38M
U.S., Canada and many others.... for now..


"Many others"? 35 airlines (and counting) have grounded their MAXs. 13 have not or have not been grounded, 5 of them US/Canadian airlines (the status of 5 MAXs operated by 3 small airlines is currently unknown).

So outside North Americs, 81 per cent of operators have grounded their MAXs. Of those very few that have not, some are effectively unable to continue operating them because of airspace restrictions across Europe (LOT, Smartwings) so I expect them to technically ground soon just for the sake of avoiding bad PR.

Simply not true.

China won't permit them to fly domestically. The airlines aren't really free to make their own decisions. They have been grounded, the airlines didn't "ground" them. And that's a huge chunk of the number of airlines.

A look at the 767 accident in Houston and the latest information, it looks like the pilots were fighting a perceived uncommanded upward trajectory at full thrust, and then crashed it into the ground. We have no absolute cause yet. All of them should be grounded around the world...


Hence my wording "13 have not or have not been grounded". I should have taken the time, admittedly, to write "have not grounded at their own will or have not been grounded by the authorities."

Aviation safety is a risk management business. Apparently you are a risk taker who has views very different from dozens of more cautious MAX 8 operators and/or aviation authorities across the globe. They have have all come to the conclusion that until the cause of the crash has been established at least to some extent it is too risky to do commercial operations with the MAX 8. And quite frankly, considering the 350 passengers killed I feel quite relieved that folks in charge at aviation authorities and airlines have a less relaxed view on gambling with someone else's life than you.

As we are just at it, let me update the list:

38 airlines (and counting) have grounded their MAXs at their will or after being instructed to do so. 12 still operate MAX 8s at this moment, 5 of them US/Canadian airlines: American, Southwest, Sunwing, Air Canada and Westjet. The others are Spicejet, flydubai, Smartwings, Copa, Fiji, S7 and SCAT. With Polish, German and Italian airspace now closed, Smartwings is pretty much trapped in the Czech republic, so they are de facto grounded as well except for some exotic charters they operate like TLV-LPA.
Last edited by vfw614 on Tue Mar 12, 2019 5:07 pm, edited 2 times in total.
 
fd122
Posts: 8
Joined: Tue Mar 11, 2008 9:20 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:06 pm

What about Sam Chui's latest video? He has a friend of a pilot who was behind this plane (on a 777 Ethopian) and said on their frequency he heard ET302's pilot say they had "unreliable airspeeds"?

Obviosly just a Youtube video but who knows..
 
LU9092
Posts: 145
Joined: Thu Oct 18, 2007 2:09 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:08 pm

People keep going on and on about the MCAS, but if the FR24 data is reasonably accurate, this aircraft had barely reached 1000' AGL in the first 3 minutes of the flight. If the plane wasn't climbing, would the pilots retract the flaps? I guess maybe if they couldn't get the nose up and they still had takeoff thrust selected, they'd quickly be overspeed for flaps down and decide to retract them, but this indicates that their control problems began before MCAS would even activate. To me it seems very likely that MCAS wasn't involved in this crash at all. ET has said the plane had just undergone a maintenance check. This makes me wonder if maybe something like a tool left behind or a fastener left undone led to the elevators being jammed or having limited range of motion.
 
luv2cattlecall
Posts: 806
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:13 pm

B777LRF wrote:
GEUltraFan9XGTF wrote:
If it is determined that broken AOA sensors contributed to faulty activation of MCAS in both scenarios, is there a chance that some preflight checklist item, maybe as something as innocent as opening and closing the forward cargo door, is adding to the likelihood that the AOA sensor is being damaged?


The AoA vanes were repositioned with the NG and are well out the way of possible GSE contact.

Problem is that MCAS depends on a single source of input, either CPT or FO AoA sensor. The system cycles between CPT and FO for each flight, which is fine, but doesn't address the fundamental problem: the system depends on a single sensor.

Aircraft hit birds every single day, several times a day. One day a sufficiently big feathered friend may take out the active AoA sensor, potentially (as bird strikes mainly happen during t/o and landing phases) leading to MCAS induced nose-down trim at a very inopportune moment.

Not my idea of sound engineering.


I didn't realize that it cycled sensors - what's the purpose behind that? And since the Lion Air aircraft had issues on its second to last flight, does that imply that both sensors were bad?
 
SimonL
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:16 pm

LU9092 wrote:
People keep going on and on about the MCAS, but if the FR24 data is reasonably accurate, this aircraft had barely reached 1000' AGL in the first 3 minutes of the flight. If the plane wasn't climbing, would the pilots retract the flaps? I guess maybe if they couldn't get the nose up and they still had takeoff thrust selected, they'd quickly be overspeed for flaps down and decide to retract them, but this indicates that their control problems began before MCAS would even activate. To me it seems very likely that MCAS wasn't involved in this crash at all. ET has said the plane had just undergone a maintenance check. This makes me wonder if maybe something like a tool left behind or a fastener left undone led to the elevators being jammed or having limited range of motion.


Depends on what you mean with just undergone maintenance. The plane was in traffic and had just return from South Africa so it seems highly unlikely that anything was done to the aircraft prior to the flight that could jam the elevators.
 
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Jouhou
Posts: 1969
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:20 pm

So Trump is bizarrely jumping into the MCAS discussion. It seems like someone gave him an oversimplified rundown on what it is, he seems to be against it for the wrong reasons.

Also can't tell if he's commenting on information he's received from investigators or something he saw on TV.
 
osiris30
Posts: 2655
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:23 pm

ELBOB wrote:
ikramerica wrote:
You can't flight test for 20 years to make sure that they didn't miss anything over the useful life of the aircraft. There is no complex piece of mechanical and or computer equipment that doesn't need some corrections after release to customers.


Why not? That's the magnitude of deveopment period typical for military platforms. 15 years for the F-35, 17 for the V-22, 11 to 13 for the Typhoon.

Why are airliners, into which we entrust the lives of hundreds, tested for just over a year?


1) They aren't tested for just over a year. There are YEARS of unit testing that happen during development. Additionally with refinement types (NEO, MAX, NG, etc., etc.) you have all the base type testing as well.

2) Cost: (source wiki)

F-35 program cost: By 2014, the program was "$163 billion over budget [and] seven years behind schedule"
V-22 program cost: The development budget was first planned for $2.5 billion in 1986, which increased to a projected $30 billion in 1988.[33] (adjust that for inflation by the way $65.31 billion today)

MAX program cost: $2–3 billion including the CFM engine development
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
KlimaBXsst
Posts: 369
Joined: Wed Jan 23, 2019 4:14 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:24 pm

Sure is going to look bad for Ethiopian and rubber necking regulators if it turns out to be something other than a flaw with the MAX such as faulty MX or political instability reasons. Especially if it precipitates any airline failures.

Have airlines been reporting any issues thus far with all the hours the MAX has been operated safely.
Last edited by KlimaBXsst on Tue Mar 12, 2019 5:24 pm, edited 1 time in total.
Aesthetically the A 340 got it right!
 
Chaostheory
Posts: 1134
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:24 pm

afriwing wrote:

Yeah at this stage I don't think the UKCAA knows any extra data (or any other authority for this matter). It's just that these national CAAs have no involvement with the MAX. Unlike the FAA and EASA who have certified the airplane.


LOL. The silliness!

Where do you think EASA get their test and evaluation pilots from? (Hint, mostly DGAC and the UK CAA).
 
vfw614
Posts: 3795
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:24 pm

It seems like someone gave him an oversimplified rundown on what it is, he seems to be against it for the wrong reasons.


How about groundig by Twitter by @therealdonaldtrump? Would be a first, but it is modern times.
 
osiris30
Posts: 2655
Joined: Sat Sep 30, 2006 10:16 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:27 pm

LU9092 wrote:
People keep going on and on about the MCAS, but if the FR24 data is reasonably accurate, this aircraft had barely reached 1000' AGL in the first 3 minutes of the flight. If the plane wasn't climbing, would the pilots retract the flaps? I guess maybe if they couldn't get the nose up and they still had takeoff thrust selected, they'd quickly be overspeed for flaps down and decide to retract them, but this indicates that their control problems began before MCAS would even activate. To me it seems very likely that MCAS wasn't involved in this crash at all. ET has said the plane had just undergone a maintenance check. This makes me wonder if maybe something like a tool left behind or a fastener left undone led to the elevators being jammed or having limited range of motion.


This. This is exactly the problem with everyone focusing on MCAS and grounding.
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
planecane
Posts: 1134
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:35 pm

fd122 wrote:
What about Sam Chui's latest video? He has a friend of a pilot who was behind this plane (on a 777 Ethopian) and said on their frequency he heard ET302's pilot say they had "unreliable airspeeds"?

Obviosly just a Youtube video but who knows..


That echoes what has been reported in various media.

I just hope that they read and release the FDR data quickly so it can either point to a MAX/MCAS issue or away and towards something else so that informed decisions about groundings, etc. can be made.
 
WIederling
Posts: 8888
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:36 pm

luv2cattlecall wrote:
I didn't realize that it cycled sensors - what's the purpose behind that? And since the Lion Air aircraft had issues on its second to last flight, does that imply that both sensors were bad?


Interesting question.
between the last two flights the plane was serviced. ( what causes the source toggle? power up ? )

If both flights saw the same AoA sensor the repair crew in between may have seen the other one. Sh*t!
additionally MCAS and its workings were unknown.
Wrong. service sees one AoA per side ( and display )

Alternate:
the flight before had problems with stick shaker (on the left seat?) and stuff but not with trim going bonkers via MCAS.
for that flight MCAS used the true ticker AoA ?
But the AoA was changed. so there is an issue on the data path from AoA to MCAS
Murphy is an optimist
 
User avatar
anfromme
Posts: 883
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:40 pm

An additional piece of info as I haven't seen this posted here yet: The Chinese Aviation Authority checked with the FAA and Boeing before they grounded the type.
https://leehamnews.com/2019/03/12/uk-ba ... grounding/

For some reason I can't copy and paste properly right now (on mobile), but the gist of ot is that they feel the resolution to MCAS issues is not straightforward and they do not have sufficient confidence in safe operations with unaltered MCAS in place.
42
 
Pluto707
Posts: 37
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:41 pm

Many specialists on this forum... a quick question from a simple ppl: MCAS will not function if: autopilot on / flaps out/ high speed/ and... any effect if GPWS is active ?
 
ikramerica
Posts: 14897
Joined: Mon May 23, 2005 9:33 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:41 pm

osiris30 wrote:
LU9092 wrote:
People keep going on and on about the MCAS, but if the FR24 data is reasonably accurate, this aircraft had barely reached 1000' AGL in the first 3 minutes of the flight. If the plane wasn't climbing, would the pilots retract the flaps? I guess maybe if they couldn't get the nose up and they still had takeoff thrust selected, they'd quickly be overspeed for flaps down and decide to retract them, but this indicates that their control problems began before MCAS would even activate. To me it seems very likely that MCAS wasn't involved in this crash at all. ET has said the plane had just undergone a maintenance check. This makes me wonder if maybe something like a tool left behind or a fastener left undone led to the elevators being jammed or having limited range of motion.


This. This is exactly the problem with everyone focusing on MCAS and grounding.

This was my point. It could be something LEAP related. Ground the MAX and NEO! It could be CFM related in general. Ground the MAX, NG, Classic, NEO, CEO, A340. It could be common to the NG, so ground them both!

It could be fuel contamination...
Of all the things to worry about... the Wookie has no pants.
 
Superboi
Posts: 20
Joined: Sat Jul 08, 2017 11:16 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:42 pm

LU9092 wrote:
People keep going on and on about the MCAS, but if the FR24 data is reasonably accurate, this aircraft had barely reached 1000' AGL in the first 3 minutes of the flight. If the plane wasn't climbing, would the pilots retract the flaps? I guess maybe if they couldn't get the nose up and they still had takeoff thrust selected, they'd quickly be overspeed for flaps down and decide to retract them, but this indicates that their control problems began before MCAS would even activate. To me it seems very likely that MCAS wasn't involved in this crash at all. ET has said the plane had just undergone a maintenance check. This makes me wonder if maybe something like a tool left behind or a fastener left undone led to the elevators being jammed or having limited range of motion.


If the plane was giving the Pilots in it wrong information, why can't you imagine it was giving FR24 recivers wrong reading too?
 
trex8
Posts: 5337
Joined: Sat Nov 02, 2002 9:04 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:43 pm

osiris30 wrote:
[ This makes me wonder if maybe something like a tool left behind or a fastener left undone led to the elevators being jammed or having limited range of motion


What sort of check on a almost new plane would likely leave a tool in some important space? Isnt it mostly a visual check?I have no idea and thats why Im asking.
On the other hand USAF just grounded and stopped taking KC46 deliveries after FO left in important spaces!
https://www.military.com/defensetech/20 ... craft.html
 
gr09
Posts: 103
Joined: Sat Jul 12, 2008 11:52 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:44 pm

B777LRF wrote:
If you're flying a NG, the engines are mounted lower and further back thus a) securing natural stability and b) cause much less of a nose-up momentum in high thrust situations.

Lower mounted engine will be further from the CoG and so creating bigger nose-up momentum (with the same thrust).
Btw. isn't the whole reason for MCAS the more forward installed engines causing significant change in CoG and affecting stall speed?
 
ikramerica
Posts: 14897
Joined: Mon May 23, 2005 9:33 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Tue Mar 12, 2019 5:44 pm

WIederling wrote:
luv2cattlecall wrote:
I didn't realize that it cycled sensors - what's the purpose behind that? And since the Lion Air aircraft had issues on its second to last flight, does that imply that both sensors were bad?


Interesting question.
between the last two flights the plane was serviced. ( what causes the source toggle? power up ? )

If both flights saw the same AoA sensor the repair crew in between may have seen the other one. Sh*t!
additionally MCAS and its workings were unknown.
Wrong. service sees one AoA per side ( and display )

Alternate:
the flight before had problems with stick shaker (on the left seat?) and stuff but not with trim going bonkers via MCAS.
for that flight MCAS used the true ticker AoA ?
But the AoA was changed. so there is an issue on the data path from AoA to MCAS

From what I understand, there was unusual behavior on the previous 4 flights at Lion. Troubleshooting was a hit or miss approach, but the aircraft never even missed a dispatch. Indicates to me "keep the bird flying" -itis.
Of all the things to worry about... the Wookie has no pants.

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