Boeing 737 Max Jets Grounded By FAA Emergency Order (nbcnews.com) 297
President Trump announced an emergency order from the Federal Aviation Administration on Wednesday grounding Boeing 737 Max jets in the wake of an Ethiopian Airlines crash Sunday and a Lion Air accident in October that together killed 346 people. The emergency order comes two days after the FAA said the Boeing 737 Max planes are still airworthy. NBC News reports: Trump's announcement came as the FAA faced mounting pressure from aviation advocates and others to ban flights of the planes pending the completion of investigations into the deadly accidents. Sunday's crash killed 157 people and the one in Indonesia in October left 189 dead. "We're going to be issuing an emergency order of prohibition to ground all flights of the 737 Max 8 and the 737 Max 9 and planes associated with that line," Trump announced, referring to "new information and physical evidence that we've received" in addition to some complaints.
The FAA said it decided to ground the jets after it found that the Ethiopian Airlines aircraft that crashed had a flight pattern very similar to the Lion Air flight. "It became clear that the track of the Ethiopian flight behaved very similarly to the Lion Air flight," said Steven Gottlieb, deputy director of accident investigations for the FAA. United States airports and airlines reacted to the order Wednesday, acknowledging that it will lead to canceled flights. American has roughly 85 flights a day on the Boeing Max 8 and Max 9 jets. United Airlines has about 40 such flights. Southwest Airlines has the most, about 150 flights per day on these types of jets out of the airline's total of about 4,100 flights daily.
The FAA said it decided to ground the jets after it found that the Ethiopian Airlines aircraft that crashed had a flight pattern very similar to the Lion Air flight. "It became clear that the track of the Ethiopian flight behaved very similarly to the Lion Air flight," said Steven Gottlieb, deputy director of accident investigations for the FAA. United States airports and airlines reacted to the order Wednesday, acknowledging that it will lead to canceled flights. American has roughly 85 flights a day on the Boeing Max 8 and Max 9 jets. United Airlines has about 40 such flights. Southwest Airlines has the most, about 150 flights per day on these types of jets out of the airline's total of about 4,100 flights daily.
Democrats insist they should fly anyway (Score:4, Funny)
Claims it was collusion with the Russians and Trump was paid in Aeroflot stock.
Boeing in not well-managed? (Score:4, Interesting)
There's only 376 built (Score:5, Interesting)
And it's only been in service since May 22, 2017 [wikipedia.org].
Considering the extreme safety of air traffic in general that's one freakishly unsafe plane.
It makes me glad I'm not the engineer/developer responsible for building that subsystem.
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It makes me glad I'm not the engineer/developer responsible for building that subsystem.
How much do you want to be the engineers actually said, "putting those engines on this air frame will cause safety issues. We shouldn't. We need to re-design the air frame to handle them." And then an exec said, "Doing it right is too expensive/time consuming, do it this way or you're fired!"
Re: There's only 376 built (Score:5, Insightful)
This reminds me of the people who read in the paper that so far in January there have been 30 murders as compared to 15 in the previous January, and then run around screaming about how the murder rate has doubled.
Only if you ignore the actual details.
Yes, if two planes of the same model have crashes for unrelated reasons that's just bad luck, it doesn't really mean anything about that specific model.
But in this case we've had two crashes that seem to have the same root cause, a defect specific to that model of plane and that pilots have been raising the alarm about well before this latest crash.
The fact that this defect caused both crashes, and it's a defect not shared by other planes, means the crash rate of other planes is much less relevant, you need to start recalculating the crash rate based on the (very limited) observations of this plane.
To hijack your example, say there have been 30 murders in January instead of the regular 15, and there's no discernible pattern otherwise, then it's probably just noise.
But if there's 15 extra murdered women between the ages 20-30, well then, you seem to have a serial killer on your hands, and if you waive it off as statistical noise you're liable to get 15 more in February.
Re: There's only 376 built (Score:5, Insightful)
Which Egypt Air flight would that be? The incidents involve Lion (Singapore) and Ethiopian (Ethiopia). You don't even have the airline straight. Switching to manual trim control won't work - pressing the trim control button on the yoke will override the MCAS for five seconds before it will re-engage. You need to actually hit the MCAS disable switch on the centre console to stop it. If your training hasn't covered the MCAS properly, you very likely won't make the mental connection to realise this is what you need to do. The Ethiopian crash happened after six minutes in the air. Given the MCAS won't engage until flaps are raised, and optimistically assuming they raised flaps after two minutes airborne, that gives them four minutes maximum to have worked out what was going on and fix it. Evidently it wasn't enough.
Re: There's only 376 built (Score:2)
Which Egypt Air flight would that be?
Obviously I meant Ethiopian Airlines. Don't be an ass.
Switching to manual trim control won't work - pressing the trim control button on the yoke will override the MCAS for five seconds before it will re-engage. You need to actually hit the MCAS disable switch on the centre console to stop it.
You have no clue what you're talking about; there is no MCAS disable switch. There is a switch which controls whether trim is actuated electrically, or manually (with a hand crank driving a cable). That switch has always been there. That's what I'm referring to when I talk about manual control, and that's always been the solution to a runaway trim condition; you cut out the electrical side of the system, and operate the trim with the hand crank.
If your training hasn't covered the MCAS properly, you very likely won't make the mental connection to realise this is what you need to do.
Pil
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Which Egypt Air flight would that be? The incidents involve Lion (Singapore) and Ethiopian (Ethiopia). You don't even have the airline straight. Switching to manual trim control won't work - pressing the trim control button on the yoke will override the MCAS for five seconds before it will re-engage. You need to actually hit the MCAS disable switch on the centre console to stop it. If your training hasn't covered the MCAS properly, you very likely won't make the mental connection to realise this is what you need to do. The Ethiopian crash happened after six minutes in the air. Given the MCAS won't engage until flaps are raised, and optimistically assuming they raised flaps after two minutes airborne, that gives them four minutes maximum to have worked out what was going on and fix it. Evidently it wasn't enough.
Lion Air is an Indonesian airline, the flight in question, JT610 was taking off from Jakarta, Indonesia.
Singapore Airlines subsidiary, Silk Air operates 737 MAX 8's but Singapore was one of the first nations to ground them.
Millenialism hits Boeing (Score:4, Informative)
Sad to see the once-proud remnant of American industrial might, Boeing, brought low like this. I thought Airbus lost it on Air France 447 when the pilot pulled his sidestick all the way back and kept it there until the plane crashed. On a Boeing, the dual control sticks would have revealed this and lives would have been saved. But now, we have this:
"One high-ranking Boeing official said the company had decided against disclosing more details to cockpit crews due to concerns about inundating average pilots with too much information â" and significantly more technical data â" than they needed or could digest."
So they:
1) Design an aircraft that has an inherent tendency to pitch up
2) Implement an a system to persistently add control inputs during critical phases of flight
3) Do NOT disclose system description to pilots in FCOM
How about fundamental rules:
Understanding what automation systems do.
Control the automated systems according to strong pilot skills.
Re:Millenialism hits Boeing (Score:5, Informative)
You forgot two other important items:
Made the algorithm rely on only a single sensor reading.
Allowed the algorithm to move the trim so far that it makes it impossible for the pilot to overpower it with the control column.
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Made the algorithm rely on only a single sensor reading.
Except they did no such thing. More reading up on the situation and less angry posting.
Allowed the algorithm to move the trim so far that it makes it impossible for the pilot to overpower it with the control column.
Safety systems should not be overpowered by panicking pilots. Airline safety has increased precisely because of the amount of control that has been removed from pilots.
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Implement an a system to persistently add control inputs during critical phases of flight
I understand that Microsoft designed this portion of the system.
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Unfortunately they designed to certification limits. They can’t just make the plane a modern fly-by-wire system with proper automation redundancy, and market conditions prevented them from designing a new plane. So, instead they tried (badly) to make the automation force the new plane to work like the old one. Badly.
Re:Millenialism hits Boeing (Score:5, Informative)
They could have made the MAX fully fly by wire, with envelope protection - the problem is, they would have lost the type rating it would share with the rest of the 737 family (and 767 and 777), meaning that pilots would have to be retrained to fly the MAX and they couldnt cross-fleet between the versions without that extra training.
But Boeing was chasing the grandfathering that makes variants such as the MAX so cheap to invest in, as it doesn't mean they have to do a full recertification, just a partial recertification, which takes less time and is cheaper.
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They would have to certify it as a new aircraft entirely, and comply with all current requirements as I understand it— it would be a new plane, without any of the benefits of being a new plane. Boeing really needs to go clean-sheet, but they did t have the time once Airbus announced the NEO.
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What is worse is that they stabbed pilots in the back and that they completely ignored the requirement that in avionics everything critical for safety needs to be redundant. Feeding this system from a single sensor is criminally negligent in the first place, but combine that with not telling the pilots and the whole thing is a trap that was sure to kill sooner or later.
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The MAX has significantly worse handling characteristics than the NG due to the repositioned engines. It's far easier for it to enter an unrecoverable stall. Because of this, they wouldn't have been able to get type certification without the MCAS. It's definitely a safety system.
Re: Millenialism hits Boeing (Score:4, Interesting)
MCAS has only a limited authority - only up to 2.5 degrees if I remember correctly. And as for the switch, it actually is present on the 737 NG since it doesn't switch off (just) the MCAS, it completely switches off electrical trim assist.
Here: http://www.flaps2approach.com/... [flaps2approach.com]
See that stab trim panel? That's the one. It is actually already present in the 737 classic. Even the original 737-100 from 1967 have that two switches at the same place, but the stab trim panel looks a bit different and is much narrower because it came directly from the 707 (where it also was at the same place).
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they completely ignored the requirement that in avionics everything critical for safety needs to be redundant.
The MCAS system is not required for safety, ergo you're just flat out wrong about this.
You have so clue about safety engineering. A system that can _endanger_ the plane if active is safety-critical. It does not have the requirement to be available, but it does have the requirement to be safe when active.
.... that's the part that's mystifying.
What does mystify you about 350 dead people?
Re: Millenialism hits Boeing (Score:2)
You have so clue about safety engineering. A system that can _endanger_ the plane if active is safety-critical.
Which would make the autopilot safety critical. You ever see a redundant autopilot, Mr Expert?
Maybe you should stop pulling definitions out of your ass.
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Actually yes. Most airliners have two autopilots - left and right. Some have an additional center autopilot.
Re: Millenialism hits Boeing (Score:2)
That's just playing games with words. In the sense that there are multiple autopilots, there are also multiple MCAS, since the MCAS is just software running on the same computers as the autopilot.
His objection was that it's criminal to feed the MCAS with data from just two AOA vanes because it is "safety critical". But the autopilot also gets data from the same vanes. Same with pressure sensors, airspeed indicators, etc. Apparently he thinks it's criminal to design aircraft the way we have been for the
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Unfortunately they designed to certification limits. [...] and market conditions prevented them from designing a new plane.
If market conditions prevented them from designing a new plane, then legal conditions should have prevented them from releasing an unsafe upgrade. I have personally had a system I designed put through the wringer of a full safety certification, you probably can't imagine how stringent and thorough these are - and should be. It is beyond comprehensible that such a blatant safety risk situation remained undetected. Apparently "we are going to lose a few percent market share to Airbus" was seen as the higher s
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The problem with your interpretation of the cause of AF447, and that you think Boeings control systems would have highlighted the inputs, is kind of tempered by the fact that Boeing aircraft have also suffered fatal stalls from pilots pulling the stick all the way back and keeping it there, which kind of indicates that that conclusion is wrong somewhat...
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As I said in my first reply to you, that doesn't hold water (even though its the go-to answer by Boeing fans) because Boeing aircraft have suffered the same pilot induced stall in the same way.
Apparently having the control column buried in your ribs isn't enough.
The real cause of AF447 is that the crew didn't believe the information that the aircraft was giving them - they didn't identify the exit from the initial sensor mismatch condition, and as a result did not carry out the proper procedure for it. Thi
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Moreover they have ignored proper procedures - once one pilot states that he has control and the other confirms, the other has no business of touching the sidestick and the rudder pedals. But the other pilot kept trying to fly the aircraft nonetheless. And ignored the plane saying out loud "dual input". In a Boeing he would just try to overpower the other pilot wondering the whole time why the controls are so unresponsive.
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The sad thing is that both AF447 and these two crashes could probably have been prevented by requiring more sensor redundancy and requiring that the redundant parts be made by at least two (or, ideally, three) different manufacturers, so that simultaneous failures caused by design flaws won't result in failure multiple sensors simultaneously.
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I know exactly how it works, I'm type rated on the A320 and the 737...
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Naa, that is the old thinking, were safety was more important than profits. These days profits are everything and who cares if 350 people get killed by some severe violations of the elementary base principles of safety-engineering.
That said, I think that the decision makers here may well have committed criminally negligent homicide in 350 cases. I mean, feeding a safety-critical system from only one sensor, not educating pilots and building an inherently unstable aircraft in the first place? How much worse
Re: (Score:2, Interesting)
Sorry, but this is bullshit. In the "good old days" the airplanes crashed far more often because neither the manufacturers nor the airlines gave a shit about safety. DC10 had a flaw with the cargo door the manufacturer knew about from the start. Took two crashes and a lawsuit for them to do something about it. The manufacturers only started to add hydraulic fuses to their aircraft designs after at least a thousand preventable deaths (DC10 and two 747, and that is just from the top of my head). Airlines gene
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You seem to be sarcasm-challenged.
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I am. But then again I also know that when people say things that aren't true and are corrected, they very often make excuses that they were just joking or that it was sarcasm.
Was there a reason to pin this on Millennials? (Score:4)
Re: Millenialism hits Boeing (Score:2)
Dafuk do millennials have to do with this? (Score:2)
Are you an Old Economy Steve who's engaging in a case of "a noun, a verb, and millenials?"
https://i.pinimg.com/originals... [pinimg.com]
Re: (Score:2)
1) Design an aircraft that has an inherent tendency to pitch up
2) Implement an a system to persistently add control inputs during critical phases of flight
3) Do NOT disclose system description to pilots in FCOM
1. Yes.
2. Sort of. There are many such systems in every plane. This isn't a bad thing. Computers are inherently better at this than people are.
3. NO.
As for 3 I'll expand a bit. The system is disclosed and known the pilots. The operation is known to pilots. What isn't disclosed is the exact inner workings of each system, and very detailed complicated bypasses and failures. Information inundation is a very real problem, and becomes even more of a problem during a stress scenario. Management of information is
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2) Implement an a system to persistently add control inputs during critical phases of flight .
The Maneuvering Characteristics Augmentation System (MCAS) adding control inputs during flights is not an issue per se. Most commercial aircraft flying today have some form of automated control inputs on the primary control surfaces for stability augmentation. Yaw dampers in the rudder for lateral stability are present in even the smallest regional jets.
A bigger issue is that a single-point of failure in the MCAS can lead to a catastrophic condition, given that the MCAS is dependent on air speed data for i
Wrongway Orangefuzz (Score:4, Informative)
Do you guys know who the director of the Federal Aviation Authority is right now? Nobody does, because Trump has never gotten around to appointing one. To be fair, he's been very busy with the golf co-championship and everything, and it probably just slipped his mind.
Nothing matters any more.
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Apparently they don't need one to make decisions.
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Your point is what?
The FAA has banned the flying of plane, isn't that what they were supposed to do?
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Do you guys know who the director of the Federal Aviation Authority is right now? Nobody does, because Trump has never gotten around to appointing one. To be fair, he's been very busy with the golf co-championship and everything, and it probably just slipped his mind.
Nothing matters any more.
He was going to try and nominate his own personal pilot to be the FAA head. But they have one in the pipeline now, I believe they are just waiting for the formal nomination.
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Trump Derangement Syndrome is not a real thing other than a HUGE example of IRONY.
Sorry if you can't enjoy the irony but that sadly is how irony works a lot of the time.
Boeing has some interesting practices.... (Score:2)
Gerald Eastman has been exposing them for years:
https://www.thelastboeinginspe... [thelastboe...pector.com]
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Except they could still fly all over USA.
When the announcement was made there were 10 of these planes in the air.
Re: Sure (Score:2)
Canada too. Maybe mexico? The carribean? Not sure, but yeah there were still plenty of viable destinations.
Re: Sure (Score:2)
Cute.
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Re: Sure (Score:2)
Not really relevant. Nobody in the USA was thinking "holy shit, we can't fly to Canada any more? Better ground the fleet!".
The US and Canada both reacted to new data about the flight path of the Egypt Air 737. Canada just reacted slightly faster.
Re: Sure (Score:2)
I didn't mention that Canada announced it a few hours before the USA; that was you (or some other anonymous twat).
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Pax? Is that the latest /. AC lingo?
It's the standard aviation industry term for passenger.
Re:Sure (Score:5, Funny)
Pax? Is that the latest /. AC lingo?
It's the standard aviation industry term for passenger.
Presumably, the term is a an abbreviation for "Paxed in like sardines".
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If by "chaotic mismanagement of the grounding" you mean, "waited until there was evidence to make a decision affecting safety" then sure. Exactly 0 incident occurred between the time of the crash in Africa and the grounding of the aircraft in the USA. Seems they acted rationally to wait for evidence before grounding aircraft out of media fear...
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No.
Addis Ababa... subtropical Africa climate...
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No.
Addis Ababa... subtropical Africa climate...
More relevantly, the altitude is 7700 ft. This narrows the safe takeoff envelope somewhat.
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In cold weather? Like colder than cruising altitude of -60C?
But, no, different plane.
Re:Turn off auto-leveling (Score:5, Informative)
It's a critical safety system, required to obtain flight certification because of the larger, more powerful engines.
Without it, on full throttle, the aircraft doesn't have enough authority to bring the nose down once it goes up too high.
That's why only the MAX variants have this system, because they have larger engines.
It has nothing to do with auto-pilot, except the system is disabled when auto-pilot is engaged.
Re:Turn off auto-leveling (Score:5, Interesting)
While you can compensate for a poor design in software, the best way is to not make the poor design in the first place.
There is a 'neutral' point for the engines to be located such that a large amount of thrust causes the body to remain mostly neutral.
Re:Turn off auto-leveling (Score:5, Informative)
A clean-sheet design would absolutely have better positioning of the engines. Unfortunately, the 737 platform comes from an era of much smaller engines, so there just isn't enough under-wing clearance to fit modern turbines in the original locations (even versions with engine updates from 10-20 years ago have odd bulges around the nacelle where parts had to be relocated to fit).
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I've long wondered why Boeing doesn't make a clean sheet replacement for the 737. For a plane sold in such vast numbers, the case for a clean redesign is much easier to make. My understanding is that currently they're looking to a 757 replacement/A321 competitor (https://en.wikipedia.org/wiki/Boeing_New_Midsize_Airplane) as their next clean design, with a 737 replacement possibly after that.
Re:Turn off auto-leveling (Score:5, Interesting)
Because it would cost too much - the MAX series was Boeing *reacting* to Airbuses launch of the A320NEO family. Boeing had had a study ongoing for years about launching a clean sheet 737 replacement, and were going down that road for introducing in the mid 2020s, but then Airbus launched the NEO and airlines started their fleet renewal processes as a result.
Boeing was caught so off guard that, when a customer no one thought would ever buy Airbus again (due to bad blood after a crash - AA wanted Airbus to take all the blame, Airbus said nope, your pilots were to blame, AA didn't place another order with Airbus as a result) placed an order for the NEO and split it by also placing an order with Boeing, they ordered "130 Airbus A320NEO aircraft AND 130 Boeing aircraft (whatever Boeing comes up with as a 737 replacement)"...
Make no mistake, the MAX is a reaction - otherwise they would have lost a lot more of the market than they already did by the procrastination they did over the A320NEO launch.
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AA wanted Airbus to take all the blame, Airbus said nope, your pilots were to blame
Shouldn't the NTSB be deciding who is to blame?
Re:Turn off auto-leveling (Score:5, Informative)
The NTSB came to its own conclusions regarding its investigation (they blamed both, but primarily the airlines training), but AA wanted Airbus to pay all the compensation and costs of the crash, as well as publicly assuming responsibility, so as to preserve AAs reputation.
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Re:Turn off auto-leveling (Score:5, Informative)
Boeing considered raising the landing gear, but considered it too costly as it meant changes to the centre wing box and associated structure, so they bodged it with an engine higher on the wing and software to compensate for the negative handling characteristics. And then they didnt tell anyone who actually flew the aircraft...
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so they bodged it
You mean made a design decision?
And then they didnt tell anyone who actually flew the aircraft...
Less hyperbole please. Not only are the changes to the design known by pilots, they are known by the frigging public.
Re:Turn off auto-leveling (Score:5, Informative)
There is a 'neutral' point for the engines to be located such that a large amount of thrust causes the body to remain mostly neutral.
Yup, and that's how the other versions are configured. These new MAX configs have physically larger engines, so - to prevent have to redesign the whole aircraft to deal with them - the engines are positioned a little bit further forward, and a centre of the engine a little bit higher off the ground (ie closer to the wing). The centre of thrust is consequently moved forward and up in relation to the centre of gravity. The result is the craft will nose-up under full throttle.
The other problem is that companies were assured pilots would not need training in the new system, however a critical difference between this system and normal auto-pilot systems is that this system does not turn off when pilots attempt an overide.
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While you can compensate for a poor design in software, the best way is to not make the poor design in the first place.
This isn't a poor design. It is just a design. Control is part of most finely tuned complex and efficient machines. Discounting anything for daring to need an instrumented control loop is just ignorance of the world around you.
Re: Turn off auto-leveling (Score:3)
It's a critical safety system, required to obtain flight certification because of the larger, more powerful engines.
Without it, on full throttle, the aircraft doesn't have enough authority to bring the nose down once it goes up too high.
I don't suppose you have any citations for any of that? If it's actually true it's certainly significant, but I've seen zero evidence of that anywhere. All the documentation talks about it being designed to assist pilots avoid a stall under very specific conditions; absolutely nothing anywhere says that its safety critical, or that the aircraft cannot be controlled at some point prior to stall.
Re: Turn off auto-leveling (Score:5, Informative)
The MCAS system was implemented because the 737-MAX engines are placed more forward of the wing which will tend to induce a nose up pitching moment particularly at high angles of attack near stall. This would've probably been a certification issue.
Now the 737 MAX had the engines placed so far forward to enable enough ground clearance. The original 50-year old 737 had low bypass engines which much smaller and could be placed directly under the wings. The newer models already ran into ground clearance issues, and this was initially solved by putting the engine systems to the side of the engine creating a distinct ovoid nacelle shape. With the new GE Leap engines, this fix was no longer sufficient due to larger engine diameter, hence the repositioning forward.
Newer aircraft like the airbus a300 series and the airbus a220 (bombardier cseries) never had this issue because they were designed to accomodate large diameter newer generation engines. The basic design of the 737 has always suffered from this flaw and really Boeing should have invested in a new aircraft design rather than try to re-engine an aircraft that was never designed for it. This was like fitting a V-12 engine into a model T.
Re: Turn off auto-leveling (Score:4, Interesting)
The MCAS system was implemented because the 737-MAX engines are placed more forward of the wing which will tend to induce a nose up pitching moment particularly at high angles of attack near stall. This would've probably been a certification issue.
It would have been a certification issue because it changes the handling characteristics of the aircraft, not because it's inherently unsafe. The MCAS is meant to automatically counter the changes so that the aircrew can fly the aircraft the same way they would a legacy 737. It has to do with Boeing being able to sell the aircraft without excessive certification requirements for pilots, rather than anything to do with safety.
This was like fitting a V-12 engine into a model T.
That's a horrible comparison. The fact that the engines are more powerful has nothing to do with anything. The placement and shape of the engine cowlings is the issue.
Re: c6gummer knows nothing about this, liar caught (Score:4, Insightful)
I would argue that either the pilot can recognize whether the plane is about to stall and ignore the AOA sensor entirely, in which case both sensors are non-essential, or the pilot can't, in which case the pilot also can't reliably determine which sensor is wrong. More importantly, if the pilot can, then the avionics systems should be able to do so as well. And if not, then that single backup is only useful when the sensor fails outright (e.g. no output, wiring fault, etc.).
And in this case, because the plane makes critical decisions that impact the airworthiness of the aircraft in response to that data and apparently cannot determine which AOA sensor is lying, having only two AOA sensors just means that the risk of the entire system failing because of incorrect data is twice as high as if it had only one AOA sensor. Assuming it is practical to fly the plane with both stall warnings and MCAS disabled, then everyone would arguably be better off if the aircraft had only a single AOA sensor, statistically speaking. If that were the case, we'd have probably had only one crash in the first two years, instead of two (not that such numbers would be good, mind you, just less appalling).
IMO, having too little redundancy can actually be worse than not having any at all. It seems likely that this aircraft, as designed, cannot be made safe unless Boeing adds either a second pair of independent AOA sensors or a couple of Pitot tubes as backups for resolving disagreements. Two sensors clearly isn't enough, given their apparent propensity for failure at low altitudes.
Re: c6gummer knows nothing about this, liar caugh (Score:3)
You're kinda right but you're missing the purpose of dual sensors. If you want true redundancy you would obviously want 3 or more sensors. When you install 2 sensors, you're not looking for one to be a backup for the other; rather you're looking for them to check each other. If they disagree then you know that the system as a whole is no longer trustworthy, and you can throw signals at the aircrew to let them know not to depend on the readings.
Now, as that relates to MCAS, Boeing had two options in the c
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It's also worth noting that, at least if the folks on PPRuNe are correct, and assuming I'm understanding correctly, even though the aircraft itself has two AOA sensors, the MCAS system only uses one of them, which is to say that if they disagree, it has no idea.
Worse, from what I've read, this aircraft in its default configuration lacks the extra AoA gauges to independently show the output of the two AoA sensors to tell you that the MCAS system is getting crap data, instead providing only an AoA Disagree l
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IMO, having too little redundancy can actually be worse than not having any at all.
It depends on the failure mode: if the failure mode is to give no readings then the twofold redundancy is better. If the failure mode is to five false readings then the twofold redundancy is worse.
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Power supplies are different. If one works, that's enough. For sensors, dual isn't good enough. You need a third one as a tie-breaker if the others disagree.
But it was pilot error, right?
Re: c6gummer knows nothing about this, liar caugh (Score:2)
That's great; I'm sure the airspace industry as a whole would love to have your input on how to automatically figure out which AOA vane is giving bad data. As of now I'm unaware of any aircraft which actually does so. Certainly none of the aircraft I've worked on do.
Also if you could please explain to me how you plan to do so, I'd love to hear it.
Re: c6gummer knows nothing about this, liar caugh (Score:2)
Dude, anyone with an understanding of basic electronics and motors can see how the AoA sensor can be checked inflight.
That's great! Please explain.
I am sure their engineer thought about how it could be done, but it was too costly to implement.
If it were just Boeing, I might buy that argument, but you're suggesting that every aircraft manufacturer in the world decided to skimp on it just to save a few bucks ... which seems a lot less likely.
You know that Boeing is going to push out new software to try to address the issue right? It's for sure not as good as if it was originally designed in silicon, but the software solution will come pretty close.
The software update is reportedly for the MCAS, not for the AOA system. Not sure why you think that's relevant.
Re: c6gummer knows nothing about this, liar caugh (Score:2)
You're proposing turning an AOA sensor into an AOA + pressure sensor. Extra complexity just adds more failure modes. What happens if the pressure sensing side of your AOA vane fails? How exactly are you detecting pressure in the first place, and how will it react to things like moisture, dust, or ice? How will you determine whether a pressure change is due to a change in airspeed, or a stuck vane?
Assuming you overcome all of those issues, what happens if the failure is electrical rather than mechanical?
Re: (Score:2)
Actually these multifunction probes (Pitot, AOA and TAT) are exactly what Airbus uses on the A380 and the A350 at the very least. The A350 has three multifunctional probes and one each of single function probes.
Re: c6gummer knows nothing about this, liar caugh (Score:2)
Having 3 multifunction probes and 1 standalone AOA vane is not an example of true redundancy with only 2 sensors ....
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This was like fitting a V-12 engine into a model T.
How dare you speak badly of such things [wikimedia.org]!
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With hindsight, it might have been better for Boeing to modernise the Boeing 757 instead of stretching the role of the Boeing 737 so much: https://www.businessinsider.co... [businessinsider.com.au]
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Though, I wonder why this issue didn't affect the A320neo Family of airliners, which use the LEAP-1A and PW1100G engines with much bigger front fans than the CFM56 and V2500 engines of the regular A320 Family of airliners.
Re: Turn off auto-leveling (Score:5, Insightful)
The A320 series had the ground clearance necessary to accomodate the new engines without needing to reposition them, hence no stability issues due to the engine placement that might have required an equivalent MCAS system.
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Probably because the 737 platform was designed in the 60s while the A320 platform was designed in the 80s.
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Apparently not, since there is a checklist for disabling it. The problem in the crashed flights is that it happened at a time when the pilots are fairly busy anyway and they didn't realize what was happening.
I'm not a pilot but I wonder if the better approach wouldn't have been to just recommend turning it off before they even take off.
According to Boeing, it's just meant to make the plane handle more like the non-MAX version of the 737.
Re: Turn off auto-leveling (Score:3)
The problem in the crashed flights is that it happened at a time when the pilots are fairly busy anyway and they didn't realize what was happening.
Not really. The first time it happened for Lion Air was as they approached 2,000 feet and went flaps up. Not a particularly busy time, but it did catch them off guard and they lost about 400 feet altitude. They, for whatever reason, then decided to drop the flaps again ... which fixed the issue since MCAS doesn't operate with flaps down. They continued to climb to about 5,000 feet at which point they went flaps up again.
From that point on they were struggling with it for something like 8 minutes, but ma
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From this [theaircurrent.com].
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In addition to more thrust, the engines are more-forward located. Additional thrust causes the plane to climb at a high angle, lessening lift until a stall is probable. The software causes the nose to point down prevent a stall. Down right in to the ground it seems.
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Unless it has access to an extra set of control surfaces that aren't accessible to the pilots, how does MCAS get this authority?
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MCAS controls the trim of the whole horizontal stabiliser (fixed stab and movable elevator move as one) whereas the pilot controls
only the elevator part. This method of trim gives full control authority at all trim settings, as opposed to an elevator trim that uses some of the elevators travel to do the trimming, limiting the maximum control throw. Every time the pilots pulled back, the system added more down trim, then they ran out of elevator throw.
Then the big lawn dart.
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It's a critical safety system, required to obtain flight certification because of the larger, more powerful engines.
Without it, on full throttle, the aircraft doesn't have enough authority to bring the nose down once it goes up too high.
That's why only the MAX variants have this system, because they have larger engines.
Not quite.
The CFM International LEAP engines were too big to fit underwing like the current engines on the Classic and Next Generation (NG) airframes, so what Boeing did was put the engines forward of the wing and higher so that the thrust was now going directly under the wing which can cause the pitch to increase. Airliners keep their engines on underwing nacelles precisely to avoid that problem but the 737 MAX couldn't because it was too low to the ground. The anti-stall system is designed to compensat
The future of aviation (Score:2)
In future airplanes will have a pilot and a dog. The dog is there to bite the pilot if he tries to touch the controls. The pilot is there to feed the dog.
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What's really sad is how people pass judgement while at the same time having no fucking clue about what they are talking about.
Re:Donald argggghhhh (Score:5, Insightful)
He just had to do it. I'm a dictator Donnie made the completely authoritarian decision to ground them.
And had he not done so, he would be a corporate stooge endangering innocent life.
Re: (Score:2)
Re:Donald argggghhhh (Score:5, Insightful)
More accurately, Dick Donnie saw FOX reporting other countries grounding the planes. At first, he thinks that would be bad for American business and after that nice CEO from Boeing gave him a ringy-dingy to pump his ego. However, aides were also watching and realized the danger that Dick Donnie would be in were one of those planes go down in America while the the FAA hadn't grounded the planes. He'd be blamed. It was unconscionable that he could be blamed, after all he is a genius. So he mouths off in a statement to the press including the bit about planes becoming too complicated for pilots...not for him, of course, he is a genius.
Meanwhile, over at the FAA and the Dept. of Transportation where Madame Chao, Mitch McConnell's wife, had been supporting the previous policy of "those crazy foreigners and their grounding OUR American planes", they get wind of Dick's pronouncement and immediately issue their own press release that claimed with consultation with Canada, they had heroically decided to ground the planes. Dick's ego is preserved, all is well.
MOD Parent up (Score:2)
Best post so far.
Could have used links to reports on how they just said the opposite for those who didn't just see and remember from a few days ago.
Good thing no emergencies requiring quick responses have happened...
Re: FAA certified an *UNSAFE* plane ! (Score:5, Informative)
No people under the jurisdiction of the FAA have died in those two crashes. Incase you are unaware, the FAA is an American agency, and only has control over US skies, and US bound flights.
The FAA pays attention to world wide flight data and bases some decisions on what it sees there. The Lion and Ethiopian crashes we're under the jurisdiction of the counties in which they originated from and crashed.
Similarly, China has its own agency too, and that agency grounded the planes well in advance of when the FAA did.
Re: FAA certified an *UNSAFE* plane ! (Score:3)
And the aircraft as a whole are airworthy. The Lion Air aircraft was not airworthy because it had not been repaired. That's a maintenance failure, which led to a crash when combined with pilot error. There's nothing in that crash to indicate that the MAX as a fleet are not airworthy. There may be something about this second crash which eventually leads to that conclusion, but at this point it's all just speculation.