"PS: You can further ask me, how do I come to that conclusion. Well. I'm here on this platform since more than 1 decade, with 1 special nickname". And that obviously makes you an expert! I guess the NTSB can just fold up shop and consider the problem solved. SMH
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Breaking news: Ethiopian Airlines flight has crashed on way to Nairobi
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Originally posted by LH-B744 View PostNow it's UR turn! What else is the MCAS than a erroneous computer system?!
Boeing either opted for the cheaper option of fail-safe or provided no redundancy at all. And the FAA let them.
To understand how a fail-safe option could lead to a crash, we need a little history lesson. Turkish Airlines flight 1951. Boeing provided fail-safe redundancy on the original NG autothrottle logic. If both radalts were not in agreement, the system was designed to disengage. The problem was, it didn't always do this. Before the Turkish 1951 crash, there had been about a dozen known cases of the autothrottle continuing to operate on a single, malfunctioning radalt. As a result, Boeing decided in 2003 to refit all NG's with a newer, reliably redundant autothrottle. But they didn't require a retrofit for existing NG's and they didn't tell NG operators (and their pilots) about the issue. in 2009, Turkish Airlines flight 1951's pre-2003 autothrottle transitioned to flare mode at the wrong moment and the aircraft crashed because the logic was erroneously operating with radalt data in disagreement. Thus, due to a known issue, it had no redundancy and was not fail-safe at all. There was a lesson it that tragedy. Did it sink in?
The MCAS system might have a similar flaw or it might have been designed without redundancy. Neither Boeing nor the FAA is currently talking about this.
But was artificial stability augmentation a bad idea to begin with?
Another history lesson: the MD-11. To achieve a lower drag by reducing the massive size of the DC-10's enpennage, it required an artificial stability augmentation system called LSAS. The system was problematic from the start. It didn't lead to any passenger fatalities, but it did lead to some pretty scary upsets. It also left the MD-11 with a rather challenging pitch behavior in the flare, which may have contributed to a couple of fatal freighter crashes. Airlines quickly dropped the MD-11, citing a lack of operational range performance, but pilots reported that is was challenging to land and I have to wonder if that was a deciding factor in its demise as a passenger aircraft.
So here we are. Boeing, having made the unwise decision in 2011 to postpone the (Y1) 737 replacement and to cobble together a higher-bypass version of their venerable 1960's airframe instead, is now dependent on artificial stability augmentation to keep it certified. That system is now proven to be unreliable (since October of last year) and known to be capable of leading to a fatal upset. Yet it remains airworthy according to the FAA. Why?
Boeing currently has over 4700 orders for the 737MAX aircraft range. It won those orders, despite fierce, race-to-the-bottom competition from the 320NEO (in which list prices were cut in half on both sides) by assuring customers that the NG had very little transition expense for airlines currently operating the NG. This is why Boeing didn't inform pilots about the new artificial stability augmentation system. This is probably also why Boeing didn't make the system more robust. That would have required additional hardware, added expense and added maintenance. Would the revelation that the new 737 depended on artificial stability augmentation, and everything that goes with it, have cost Boeing some of those orders? Would grounding the fleet and requiring a significant system modification following a fatal crash in October have caused them to lose some of those orders? How disinterested is the FAA with a company that makes a significant contribution to the nation's export economy?
If this crash turns out to be a repeat performance of last October's crash--and really, even if it doesn't--the fleet needs to be grounded and MCAS needs to be redesigned to a higher, fail-passive standard of redundancy. This means adding hardware as well as modifying software. It means holding Boeing to the same standard required of Airbus when they first certified computer-augmented flight control. Once this is done, the 737MAX will be among the safest aircraft in the skies.
But it will require Boeing to pay the tough price for its previous lack of vision and its short-term-investor-driven management culture. Boeing is unlikely to do that unless the FAA ends this bromance and shows the same some tough love they gave to Airbus.
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I cannot understand how in the world it can be even just supposed that an MCAS issue can result in pilot calling Air Traffic Control saying "Huston, we have a problem, we are turning back" and an airplane crashing a few seconds later.
The second thing I cannot understand is how it is possible that the root cause of an accident can been found even before flight data recorders have been found, not to mention decoded, not to mention analyzed.
It's just a fake news, guys, or, better defined, a SNAS issue (Social Network Augmentation System)...
In no way we can know the cause of this accident earlier than 1 week (or 2, or 10) from now.
Let the data speak, then speak.
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Originally posted by Gabriel View PostI am willing to give you that the Lion Air crash was due to the MCAS, even when that's a gross over-simplification and even misleading because the in the previous flight the airplane had exactly the same problem that the crew managed relatively well (at least well enough not to crash) and the airline released the airplane for the next flight without solving the problem and with a crew that did not know how to manage a trim malfunction (induced by an MCAS malfunction induced by a faulty AoA sensor and a design that was not tolerant to a single-sensor failure).
Having said that, if the Ethiopian crash ends up being an exact carbon copy of the Lion Air crash - and I mean exactly one for one - then this would be inexcusable for the crew as well, not to have learned from Lion Air. And for now it seems there are a lot of similarities between the two crashes. So a crappy, deficient design for sure, I'm afraid. I'm almost certain this would end up being the MCAS, and the only question would be whether the crew had not learned the procedures after Lion Air, or if there was some additional unexpected behavior by the automation.
I personally think this could end up being disastrous for Boeing, but also for the FAA. As of this morning, at least 40% of the global MAX fleet was self-grounded, and just now the UK has joined as well. And the FAA are just reiterating how safe this plane is. I mean, just wow.
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Originally posted by Evan View PostThe 737MAX is not airworthy without MCAS. MCAS is artificial stability augmentation. It was created to overcome the pitching effect that resulted from Boeing's decision to stuff 70" turbofans under the wing of an aircraft originally designed for 40" turbofans. This required the engines to be moved further forward of the wing, which produced a more pronounced pitching effect at high power and high pitch attitude than the FAA was willing to accept. Boeing decided to solve this with software alone. And they did. MCAS works. Except when it has bad data to guide it. The solution is... oh... so... simple: data source redundancy. Either MCAS doesn't have this, or it's not working reliably. There are two ways to go about this redundancy. There is the fail-safe approach and there is the fail-passive approach. The fail-safe approach is cheaper. It simply requires the system to disengage if both data sources are in disagreement with one another (beyond a safe threshold). But this is problematic because this means a single sensor failure renders the aircraft unstable at certain attitudes (and thus no longer airworthy). The fail-passive approach is more expensive. It requires you to add a third data source and logic to 'vote' between all three sources. If two of the three sources are in agreement, the system deactivates the bad sensor and the remaining two continue to provide artificial stability for the rest of the flight.
Boeing either opted for the cheaper option of fail-safe or provided no redundancy at all. And the FAA let them.
To understand how a fail-safe option could lead to a crash, we need a little history lesson. Turkish Airlines flight 1951. Boeing provided fail-safe redundancy on the original NG autothrottle logic. If both radalts were not in agreement, the system was designed to disengage. The problem was, it didn't always do this. Before the Turkish 1951 crash, there had been about a dozen known cases of the autothrottle continuing to operate on a single, malfunctioning radalt. As a result, Boeing decided in 2003 to refit all NG's with a newer, reliably redundant autothrottle. But they didn't require a retrofit for existing NG's and they didn't tell NG operators (and their pilots) about the issue. in 2009, Turkish Airlines flight 1951's pre-2003 autothrottle transitioned to flare mode at the wrong moment and the aircraft crashed because the logic was erroneously operating with radalt data in disagreement. Thus, due to a known issue, it had no redundancy and was not fail-safe at all. There was a lesson it that tragedy. Did it sink in?
The MCAS system might have a similar flaw or it might have been designed without redundancy. Neither Boeing nor the FAA is currently talking about this.
But was artificial stability augmentation a bad idea to begin with?
Another history lesson: the MD-11. To achieve a lower drag by reducing the massive size of the DC-10's enpennage, it required an artificial stability augmentation system called LSAS. The system was problematic from the start. It didn't lead to any passenger fatalities, but it did lead to some pretty scary upsets. It also left the MD-11 with a rather challenging pitch behavior in the flare, which may have contributed to a couple of fatal freighter crashes. Airlines quickly dropped the MD-11, citing a lack of operational range performance, but pilots reported that is was challenging to land and I have to wonder if that was a deciding factor in its demise as a passenger aircraft.
So here we are. Boeing, having made the unwise decision in 2011 to postpone the (Y1) 737 replacement and to cobble together a higher-bypass version of their venerable 1960's airframe instead, is now dependent on artificial stability augmentation to keep it certified. That system is now proven to be unreliable (since October of last year) and known to be capable of leading to a fatal upset. Yet it remains airworthy according to the FAA. Why?
Boeing currently has over 4700 orders for the 737MAX aircraft range. It won those orders, despite fierce, race-to-the-bottom competition from the 320NEO (in which list prices were cut in half on both sides) by assuring customers that the NG had very little transition expense for airlines currently operating the NG. This is why Boeing didn't inform pilots about the new artificial stability augmentation system. This is probably also why Boeing didn't make the system more robust. That would have required additional hardware, added expense and added maintenance. Would the revelation that the new 737 depended on artificial stability augmentation, and everything that goes with it, have cost Boeing some of those orders? Would grounding the fleet and requiring a significant system modification following a fatal crash in October have caused them to lose some of those orders? How disinterested is the FAA with a company that makes a significant contribution to the nation's export economy?
If this crash turns out to be a repeat performance of last October's crash--and really, even if it doesn't--the fleet needs to be grounded and MCAS needs to be redesigned to a higher, fail-passive standard of redundancy. This means adding hardware as well as modifying software. It means holding Boeing to the same standard required of Airbus when they first certified computer-augmented flight control. Once this is done, the 737MAX will be among the safest aircraft in the skies.
But it will require Boeing to pay the tough price for its previous lack of vision and its short-term-investor-driven management culture. Boeing is unlikely to do that unless the FAA ends this bromance and shows the same some tough love they gave to Airbus.
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Originally posted by flashcrash View PostUK CAA re Boeing 737 MAX Aircraft: "We have, as a precautionary measure, issued instructions to stop any commercial passenger flights from any operator arriving, departing or overflying UK airspace"
https://www.caa.co.uk/News/Boeing-737-MAX-Aircraft/
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Originally posted by Black Ram View PostAs I commented in the Lion Air crash thread, it was just by pure chance that the previous Lion Air flight did not crash. It was probably the result of the captain giving control to the F/A, and concentrating all his attention and resources to troubleshooting any anomalies. Judging by their comments in the post-flight log, the crew had absolutely no idea what had happened to them, and concentrated their attention on IAS and AoA disagree, leaving some confusing (because they were themselves confused) comments about about the "elevator feel computer".
The Lion Air crash crew also knew that they had a trim issue. Not only they felt the nose-down force, but it is impossible not to note (see and hear) the trim wheel spinning, and their first reaction to use the electric trim switch to fight back was a correct and effective countermeasure. They didn't go to the second step of reaching out to the cutout switches and, on top of that, for some reason that I still don't understand, they stopped fighting back with the electric trim switch.
Having said that, if the Ethiopian crash ends up being an exact carbon copy of the Lion Air crash - and I mean exactly one for one - then this would be inexcusable for the crew as well, not to have learned from Lion Air.
So a crappy, deficient design for sure, I'm afraid.
I'm almost certain this would end up being the MCAS
I don't see any compelling reason to believe (let alone feel almost certain) neither that it was or that it wasn't MCAS related.
and the only question would be whether the crew had not learned the procedures after Lion Air, or if there was some additional unexpected behavior by the automation.
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
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Originally posted by Gabriel View PostThat would speak horribly for both Ethiopian and this crew.
The 200 hour F/O is not helping matters, but still... It seems unthinkable that this PIC would fail to follow the basic trim runaway procedure.
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Originally posted by Gabriel View PostAnd I disagree, it was not just pure chance. Yes, they didn't know about the MCAS, and they were confused about what caused the trim behavior. But while they didn't know how or why what happened happened, they knew that they had a rogue trim and they first stopped the motion with the electric trim switch and then disconnected it with the cutout switches. That's what you have to do if you have a trim runaway regardless of how and why the trim went runaway. And they didn't just played with all the switches they could found until they happened to toggle the trim cutout switches just by chance. They correctly identified that there was an issue with the electric trim, knew that the cutout switches should stop the electric trim, and went for them.
The Lion Air crash crew also knew that they had a trim issue. Not only they felt the nose-down force, but it is impossible not to note (see and hear) the trim wheel spinning, and their first reaction to use the electric trim switch to fight back was a correct and effective countermeasure. They didn't go to the second step of reaching out to the cutout switches and, on top of that, for some reason that I still don't understand, they stopped fighting back with the electric trim switch.
I agree with that so much, except with the "exact copy paste" part. You don't know how much I hope this was not an MCAS or any trim runway related accident that was not worked with the electric trim trim switches, the trim cutout switches, and even grabbing the wheel if necessary.. That would speak horribly for both Ethiopian and this crew.
I agree.
I don't know why you are almost certain. Yes, there are similarities but also there are some contradicting rumors, and zero official reports so far.
I don't see any compelling reason to believe (let alone feel almost certain) neither that it was or that it wasn't MCAS related.
Even if there was some additional unexpected behavior, I would like to see what that unexpected behavior was. Again, at this point, after the Lion Air crash, it should be clear that anything related with an electric trim motion being out of control and causing control problems, should be dealt with immediately killing the electric trim.
Not sure if the trim wheel makes any noise anymore Gabe. As of the 400 on the 74 it doesn't, can't even see a wheel anymore.
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Originally posted by avherald.comOn Mar 12th 2019 Boeing issued following release with respect to MCAS, Lion Air Flight 610 and Ethiopian flight 302:
For the past several months and in the aftermath of Lion Air Flight 610, Boeing has been developing a flight control software enhancement for the 737 MAX, designed to make an already safe aircraft even safer. This includes updates to the Maneuvering Characteristics Augmentation System (MCAS) flight control law, pilot displays, operation manuals and crew training. The enhanced flight control law incorporates angle of attack (AOA) inputs, limits stabilizer trim commands in response to an erroneous angle of attack reading, and provides a limit to the stabilizer command in order to retain elevator authority.
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The FAA says it anticipates mandating this software enhancement with an Airworthiness Directive (AD) no later than April. We have worked with the FAA in development of this software enhancement**.
I mean, why wouldn't you?
**by 'enhancement', they mean 'fix'.
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Originally posted by ATLcrew View PostI highly doubt that "most 777 drivers" hand-fly until 10,000'. Although...considering that many of them (at least among US carriers) are ridiculously senior and barely fly at all, who knows, maybe they do more manual work than I think...If it 'ain't broken........ Don't try to mend it !
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