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.
Pilots on a previous flight correctly identified it as a malfunctioning trim system, and did exactly what I explained. They survived because they followed established procedures, not because they had any more info about MCAS.
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.
We don't even know if the Ethiopian Airlines crash was related to MCAS, but, assuming it was, it only takes a few seconds to realize that your trim isn't working right, and to flip the correct switch. Given that the MCAS system was in the news after the Lion Air crash, and that Boeing put out advisories subsequent to the crash, it seems a near certainty that the Ethiopian Airlines crew would have known about it, and should have been able to correct the situation immediately. What exactly happened won't be clear until the black boxes are examined over the next couple days.
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 case of sensor disagreement:
1. Go with the best-case sensor reading, in which case you will likely not react to an actual stall condition. 2. Go with the worst case reading, in which case you may react to a condition which isn't actually a stall. 3. Ignore them completely, in which case the MCAS system becomes inoperative and can't prevent a stall.
They decided to go with the worst case reading because, generally speaking, stalls are bad. You want to prevent them as much as possible. Going nose down when you don't need to is also bad, but not nearly AS bad unless you happen to be close to the ground.... and they tried to make sure that wouldn't happen by disabling the system when the flaps are down. Even if you are at a relatively low altitude with the flaps up for some reason, a stall is typically worse than going nose down because a stall requires significant altitude to recover from.
It was a rational design choice. Where they probably erred the most was in not telling pilots about it. I'm not sure that it would have made a difference to that Lion Air crew even if they had been told, but they still should have been informed.
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? What happens if the vane is installed incorrectly and therefore misaligned? What happens if the vane is bent, and otherwise functioning perfectly but giving a slightly different reading due to an offset angle?
You're certainly arrogant enough to think you can in 5 seconds come up with a solution which nobody in the aerospace industry has ever come up with, but arrogance and competence are not the same thing.
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.
but combine that with not telling the pilots and the whole thing is a trap that was sure to kill sooner or later.
While I agree that pilots should have been told about the system, all that the pilots had to do was follow the same runaway-trim checklist which they've always had. How exactly you conclude that an aircraft which requires no new skills or training is a "trap which was sure to kill".... that's the part that's mystifying.
If the Lyon Air crew had experienced a runaway-trim condition caused by something other than MCAS, do you really think they would have reacted appropriately to it? Or would they have done exactly what they did in this situation? What exactly made this situation unique, in your mind?
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 maintaining altitude the entire time. It's mind boggling that they didn't think to either drop the flaps again, or to go to their runaway trim checklist. They continued to fight it until shortly before the end, at which point the black box makes it look like they just gave up and plumeted out of the sky.
tl;dr: "busy" had nothing to do with it.
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.
Not really, unless there's a lot more wrong with the system than we currently know. It does actually make the aircraft easier to fly without needing conversion training, and it does help prevent stalls. Pilots just need to follow their checklist if it acts up.
According to Boeing, it's just meant to make the plane handle more like the non-MAX version of the 737.
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.
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.
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.
If that were true you would have a point, but the sad fact is that you're just repeating bullshit. We don't know that there's a defect, and pilots have not been "raising the alarm... before this last crash". The lion air crash primarily happened because the AOA system was unserviceable on multiple flights and was never fixed. Pilots on those previous flights also ran into the same issues, and they reacted appropriately by switching to manual trim control.
There have been reports of other pilots reporting similar symptoms much earlier on different aircraft, however those occured with the autopilot engaged, meaning that the MCAS system wasn't even active at the time. If those were real occurrences they should be investigated, but they do nothing to support your claim of a common defect.
You're drawing a whole lot of conclusions with very little evidence. Given the flight profile of the Egypt Air flight it is justified to suspect that MCAS may have been involved, and to ground the aircraft just in case. However it doesn't tell us for certain that it was involved, nor does it tell us why it may have kicked in, nor does it tell us why the pilots couldn't compensate for it. In short we know absolutely nothing about it, yet you feel justified in concluding that the aircraft is insanely unsafe.
Dual systems are standard on aircraft which detect AOA (not all do). It should be obvious to anyone but you that a dual system is redundant, but that the redundancy cannot be automated. If one sensor is giving bad data there's no way of automatically detecting which one is right and which one is wrong. Therefore the computer has to either make a best-guess, or it has to default to a single channel. This, again, is the same on all aircraft which have AOA sensors.
Of course none of that has anything to do with either the fact that the aircraft was allowed to fly with a known AOA problem, or the fact that the pilots didn't seem to have any idea how to disengage electrical actuation of the trim system.
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.
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.
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.
Yes, the people living under the boot of their NK theocrat/necrocrat/dictator really want him to have Nuclear weapons so that he can stand up to random Slashdot commenters.
I could construct an argument that agnosticism takes an "absolute positions on something that is not falsifiable". The fact that you can construct an argument says nothing about whether or not that argument is valid.
The MCAS system will CONTINUE to make control inputs which force the aircraft to pitch down, and thus can over ride the control inputs made by the crew.
Pure nonsense. The MCAS system doesn't act directly on the controls, it controls trim. Even maximum trim can be overcome by the pilots to level out the plane and then figure out what's going on. Based on their flight path we know that they were, in fact, able to overcome it multiple times.
It will over time become apparent that the aircraft which have crashed were crewed by pilots who did NOT receive complete training in the use of the MCAS system.
There is no "use of the MCAS". It's an automatic system. You don't use it, you let it do it's thing. If your mechanics are retarded and their negligence causes your MCAS to kick in when it shouldn't, you treat it the same way as you would any other runaway trim situation. Had the aircrew on the Lion Air flight followed the same checklist which has been in use for decades, they and their passengers would have lived.
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So, basically, Russians can still send and recieve encrypted email no problem.... they just can't send it to Russian mail servers.
Wtf is the point of that? Trying to drive their own email providers out of business? Or is it just a really silly oversight?
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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.
Pilots on a previous flight correctly identified it as a malfunctioning trim system, and did exactly what I explained. They survived because they followed established procedures, not because they had any more info about MCAS.
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.
We don't even know if the Ethiopian Airlines crash was related to MCAS, but, assuming it was, it only takes a few seconds to realize that your trim isn't working right, and to flip the correct switch. Given that the MCAS system was in the news after the Lion Air crash, and that Boeing put out advisories subsequent to the crash, it seems a near certainty that the Ethiopian Airlines crew would have known about it, and should have been able to correct the situation immediately. What exactly happened won't be clear until the black boxes are examined over the next couple days.
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.
Having 3 multifunction probes and 1 standalone AOA vane is not an example of true redundancy with only 2 sensors ....
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 case of sensor disagreement:
1. Go with the best-case sensor reading, in which case you will likely not react to an actual stall condition.
2. Go with the worst case reading, in which case you may react to a condition which isn't actually a stall.
3. Ignore them completely, in which case the MCAS system becomes inoperative and can't prevent a stall.
They decided to go with the worst case reading because, generally speaking, stalls are bad. You want to prevent them as much as possible. Going nose down when you don't need to is also bad, but not nearly AS bad unless you happen to be close to the ground .... and they tried to make sure that wouldn't happen by disabling the system when the flaps are down. Even if you are at a relatively low altitude with the flaps up for some reason, a stall is typically worse than going nose down because a stall requires significant altitude to recover from.
It was a rational design choice. Where they probably erred the most was in not telling pilots about it. I'm not sure that it would have made a difference to that Lion Air crew even if they had been told, but they still should have been informed.
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? What happens if the vane is installed incorrectly and therefore misaligned? What happens if the vane is bent, and otherwise functioning perfectly but giving a slightly different reading due to an offset angle?
You're certainly arrogant enough to think you can in 5 seconds come up with a solution which nobody in the aerospace industry has ever come up with, but arrogance and competence are not the same thing.
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.
but combine that with not telling the pilots and the whole thing is a trap that was sure to kill sooner or later.
While I agree that pilots should have been told about the system, all that the pilots had to do was follow the same runaway-trim checklist which they've always had. How exactly you conclude that an aircraft which requires no new skills or training is a "trap which was sure to kill" .... that's the part that's mystifying.
If the Lyon Air crew had experienced a runaway-trim condition caused by something other than MCAS, do you really think they would have reacted appropriately to it? Or would they have done exactly what they did in this situation? What exactly made this situation unique, in your mind?
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 maintaining altitude the entire time. It's mind boggling that they didn't think to either drop the flaps again, or to go to their runaway trim checklist. They continued to fight it until shortly before the end, at which point the black box makes it look like they just gave up and plumeted out of the sky.
tl;dr: "busy" had nothing to do with it.
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.
Not really, unless there's a lot more wrong with the system than we currently know. It does actually make the aircraft easier to fly without needing conversion training, and it does help prevent stalls. Pilots just need to follow their checklist if it acts up.
According to Boeing, it's just meant to make the plane handle more like the non-MAX version of the 737.
Yep, that's the gist of it.
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.
I didn't mention that Canada announced it a few hours before the USA; that was you (or some other anonymous twat).
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.
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.
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.
If that were true you would have a point, but the sad fact is that you're just repeating bullshit. We don't know that there's a defect, and pilots have not been "raising the alarm ... before this last crash". The lion air crash primarily happened because the AOA system was unserviceable on multiple flights and was never fixed. Pilots on those previous flights also ran into the same issues, and they reacted appropriately by switching to manual trim control.
There have been reports of other pilots reporting similar symptoms much earlier on different aircraft, however those occured with the autopilot engaged, meaning that the MCAS system wasn't even active at the time. If those were real occurrences they should be investigated, but they do nothing to support your claim of a common defect.
You're drawing a whole lot of conclusions with very little evidence. Given the flight profile of the Egypt Air flight it is justified to suspect that MCAS may have been involved, and to ground the aircraft just in case. However it doesn't tell us for certain that it was involved, nor does it tell us why it may have kicked in, nor does it tell us why the pilots couldn't compensate for it. In short we know absolutely nothing about it, yet you feel justified in concluding that the aircraft is insanely unsafe.
The 737 incorporates dual AOA vanes, therefore it is not "single instrument".
https://www.seattletimes.com/b...
Dual systems are standard on aircraft which detect AOA (not all do). It should be obvious to anyone but you that a dual system is redundant, but that the redundancy cannot be automated. If one sensor is giving bad data there's no way of automatically detecting which one is right and which one is wrong. Therefore the computer has to either make a best-guess, or it has to default to a single channel. This, again, is the same on all aircraft which have AOA sensors.
Of course none of that has anything to do with either the fact that the aircraft was allowed to fly with a known AOA problem, or the fact that the pilots didn't seem to have any idea how to disengage electrical actuation of the trim system.
Please stop making up nonsense.
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.
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.
Cute.
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.
Canada too. Maybe mexico? The carribean? Not sure, but yeah there were still plenty of viable destinations.
Yes, the people living under the boot of their NK theocrat/necrocrat/dictator really want him to have Nuclear weapons so that he can stand up to random Slashdot commenters.
I could construct an argument that agnosticism takes an "absolute positions on something that is not falsifiable". The fact that you can construct an argument says nothing about whether or not that argument is valid.
They're uncertain about it to the same extent as they're uncertain about whether or not being bitten by a radioactive spider gives you super powers.
50 billion units.
What you said was pretty fucking pointless, as usual. I was being generous and assuming you actually had a point.
The MCAS system will CONTINUE to make control inputs which force the aircraft to pitch down, and thus can over ride the control inputs made by the crew.
Pure nonsense. The MCAS system doesn't act directly on the controls, it controls trim. Even maximum trim can be overcome by the pilots to level out the plane and then figure out what's going on. Based on their flight path we know that they were, in fact, able to overcome it multiple times.
It will over time become apparent that the aircraft which have crashed were crewed by pilots who did NOT receive complete training in the use of the MCAS system.
There is no "use of the MCAS". It's an automatic system. You don't use it, you let it do it's thing. If your mechanics are retarded and their negligence causes your MCAS to kick in when it shouldn't, you treat it the same way as you would any other runaway trim situation. Had the aircrew on the Lion Air flight followed the same checklist which has been in use for decades, they and their passengers would have lived.
Characterizing the 737 MAX as "an airplane that can't flu straight" is beyond idiotic.
Almost as idiotic as statements like "we are so much better in $year that $random_thing should never go wrong".
"ProtonMail is not blocked in the normal way, it's actually a bit more subtle. They are blocking access to ProtonMail mail servers. So Mail.ru -- and most other Russian mail servers -- for example, is no longer able to deliver email to ProtonMail, but a Russian user has no problem getting to their inbox."
So, basically, Russians can still send and recieve encrypted email no problem .... they just can't send it to Russian mail servers.
Wtf is the point of that? Trying to drive their own email providers out of business? Or is it just a really silly oversight?