JBirdAV8r wrote:

To those wondering about why the pilots might have pushed the engines up to max thrust in the final seconds: it might have been a last-ditch and futile attempt to raise the nose. As the thrust line is below the CG on a 737, adding power creates a nose-up pitch moment. I don’t think it suggests disorientation; I think it could have been a last-ditch effort to regain some nose-up pitch authority.

Thanks for bringing a plausible reason.
Though one can wonder how much pitch change rate the engine could provide, especially considering the low altitude they at.

PixelFlight wrote:

kalvado wrote:

PixelFlight wrote:

What the options at this point:
1) It's ok to flight an aircraft without any redundancy on the sensor used by a required protection authority over the pilots. Seriously ?
2) The protection authority over the pilots is not required, so remove it. Stuck in the past.
3) The sensors redundancy is required for a protection authority over the pilots. Grounding.
I am missing something ?

4) Publish more information on these issues and continue flying the fleet as the fix is designed, certified and implemented. Pilots should be able to handle the issue with all new knowledge.
My bet is on (4)

Your 4) in in fact 1) now and then 3) later. The options is about the certification, once 1) is not allowed anymore, this must be 2) or 3).

There is a well established practice of MEL deferrals. Essentially same situation: a part required for safe operation is not working, but risk is low enough enough to allow operations with some limitations...

kalvado wrote:

PixelFlight wrote:

kalvado wrote:

4) Publish more information on these issues and continue flying the fleet as the fix is designed, certified and implemented. Pilots should be able to handle the issue with all new knowledge.
My bet is on (4)

Your 4) in in fact 1) now and then 3) later. The options is about the certification, once 1) is not allowed anymore, this must be 2) or 3).

There is a well established practice of MEL deferrals. Essentially same situation: a part required for safe operation is not working, but risk is low enough enough to allow operations with some limitations...

This is option 2).

Finn350 wrote:

Furthermore, it is very unlikely that the cause of the accident is related to a coding error. Based on the current information, the cause is related to the design of the MCAS under certain malfunctions, and no code is needed to review the design.

In my view it may turn out that the cause is not the MCAS design per se but proper knowledge and education about it. This may turn out to be incorrect but it seems so far that all these guys had to do was the exact thing the prior guys did. That to me is the worst and saddest part of this tragedy. The solution had just been employed and these guys didn't know about it. I guess that's not normal procedure though it seems like it should be. If I were a pilot and had nearly killed myself and all pax on a flight I'd leave a sticky note on the cockpit window advising the next pilot that "this plane almost killed us last trip..here's what happened". I really can't wrap my head around this lack of critical communication hand-off, not just re Lion Air but anywhere it may be absent from procedure.

Meanwhile questions re CVR go unanswered and the "news" regarding its recovery is practically nil.

Pages and pages of detailed analysis on this plane's systems but veritably nothing on underwater recovery of a CVR....

wingman wrote:

Finn350 wrote:

Furthermore, it is very unlikely that the cause of the accident is related to a coding error. Based on the current information, the cause is related to the design of the MCAS under certain malfunctions, and no code is needed to review the design.

In my view it may turn out that the cause is not the MCAS design per se but proper knowledge and education about it. This may turn out to be incorrect but it seems so far that all these guys had to do was the exact thing the prior guys did.

AoA sensor do fail sometimes, this is hard fact, no matter what.
Human pilot do error sometimes, this is hard fact, no matter what.
737MAX have a "unsafe condition" (per EAD) that directly link the two above events to cause "the flight crew to have difficulty controlling the airplane, and lead to excessive nose-down attitude, significant altitude loss, and possible impact with terrain." (per EAD). The link is the MCAS that 1) don't have AoA sensor redundancy 2) is a required protection 3) have authority over the pilots.

wingman wrote:

Finn350 wrote:

Furthermore, it is very unlikely that the cause of the accident is related to a coding error. Based on the current information, the cause is related to the design of the MCAS under certain malfunctions, and no code is needed to review the design.

In my view it may turn out that the cause is not the MCAS design per se but proper knowledge and education about it. This may turn out to be incorrect but it seems so far that all these guys had to do was the exact thing the prior guys did. That to me is the worst and saddest part of this tragedy. The solution had just been employed and these guys didn't know about it. I guess that's not normal procedure though it seems like it should be. If I were a pilot and had nearly killed myself and all pax on a flight I'd leave a sticky note on the cockpit window advising the next pilot that "this plane almost killed us last trip..here's what happened". I really can't wrap my head around this lack of critical communication hand-off, not just re Lion Air but anywhere it may be absent from procedure.

While it is true that the accident could likely have been prevented if the pilots had followed the Runaway Stabilizer NCC, the design as it is now under an AOA malfunction is too dangerous. I would be very surprised if Boeing were not already re-designing MCAS logic under that malfunction.

N212R wrote:

Meanwhile questions re CVR go unanswered and the "news" regarding its recovery is practically nil.

Pages and pages of detailed analysis on this plane's systems but veritably nothing on underwater recovery of a CVR....

Yes there are some news in local Indonesian news outlet. In summary they are still looking for:
1) DP2 vessels as there are submarine oil & gas pipeline around the search area.
2) A type of suction dredger system to move mud from the sea bed
3) Better divers support system so divers can stay longer underwater.

N212R wrote:

Meanwhile questions re CVR go unanswered and the "news" regarding its recovery is practically nil.

Pages and pages of detailed analysis on this plane's systems but veritably nothing on underwater recovery of a CVR....

I am really not sure what you are expecting? No one here has obvious involvement in the search for the CVR. I am absolutely certain we want it found.

Casting aspersions on here and expecting a response is frankly facile.

N212R wrote:

Meanwhile questions re CVR go unanswered and the "news" regarding its recovery is practically nil.

Pages and pages of detailed analysis on this plane's systems but veritably nothing on underwater recovery of a CVR....

The area of search has a lot of cables and pipes preventing ships requiring anchor to be deployed.
They have requisitioned a heavy ship this week, which does not require anchoring to expedite the search.

Finn350 wrote:

While it is true that the accident could likely have been prevented if the pilots had followed the Runaway Stabilizer NCC, the design as it is now under an AOA malfunction is too dangerous. I would be very surprised if Boeing were not already re-designing MCAS logic under that malfunction.

As a regular flyer I certainly support any action to make systems and flying in general safer. But I still hope that where it's not already in place at any airline that there be a process whereby pilots encountering a life threatening situation on a flight have a means of clearly communicating the event and, most importantly, the actions they took to save themselves and their passengers to the next crew. The accident pilots died trying to figure something out that the pilots on the prior flight seemingly figured out at the first sign of trouble. That is just shocking to me. A toilet is broken or a windshield cracks, I get that. But bells going off, sticks shaking, pilots hand flying at a lower altitude after disabling core automated systems..that sounds like an extremely serious and rare event.

As always I must add the disclaimer that I'm no expert so maybe I'm missing something that logically explains this.

So I have a question, after reading everything that is up to date on this incident. It is more a human-related question than a design-related question, but nonetheless....

WHY would an airplane with such sensor discrepancies be allowed to (be able to) take off? According to the detailed graphs that have been constructed from the FDR, this plane's two AOA sensors were feeding back conflicting readings when the aircraft was ON THE GROUND, while it was taxiing to the runway.

Now I do understand that stick shaker, stall warnings etc. will only occur once airborne.......but my larger query is why airplane systems are designed in such a way to allow a passenger jet to configure itself to take off, and allow the pilots to begin their takeoff roll ALL THE WHILE with faulty sensors and two conflicting data streams feeding into the ADIRU???

This situation seems absolutely preposterous to me (as a layman passenger). I'm sorry - it just does. The fact that passenger aircraft carrying hundreds of people are allowed to become airborne when the plane's computers ALREADY know there is a sensor problem (discrepancy in the VERY least) just blows me away. AoA sensors, pitots, these sensors are how the crew manage to keep the aircraft in the AIR. A damaged/broken/incorrect sensor on a plane like this should automatically trigger the systems to disallow the plane to take off. (Note I am not suggesting that sensor issues should be a veritable kill switch - as obviously in-flight sensor issues due to icing etc. will continue to be commonplace.)

I will repeat what I posted weeks ago. This airplane was in NO WAY airworthy and the fact that it was cleared for service on the incident date (or previous two flights) is just astounding.

Now we have to get into the nitty-gritty of WHY the mx logs state that the repair work that was done to it satisfied ground tests prior to takeoff, and why AOA disagrees were not seen during their testing before the final flight.

Trin

Trin wrote:

WHY would an airplane with such sensor discrepancies be allowed to (be able to) take off? According to the detailed graphs that have been constructed from the FDR, this plane's two AOA sensors were feeding back conflicting readings when the aircraft was ON THE GROUND, while it was taxiing to the runway.

AOA sensors only work when there is sufficient airflow around them. They are not designed to give correct angle of attack while the aircraft is taxiing on the ground. This is by design.

wingman wrote:

Finn350 wrote:

While it is true that the accident could likely have been prevented if the pilots had followed the Runaway Stabilizer NCC, the design as it is now under an AOA malfunction is too dangerous. I would be very surprised if Boeing were not already re-designing MCAS logic under that malfunction.

As a regular flyer I certainly support any action to make systems and flying in general safer. But I still hope that where it's not already in place at any airline that there be a process whereby pilots encountering a life threatening situation on a flight have a means of clearly communicating the event and, most importantly, the actions they took to save themselves and their passengers to the next crew. The accident pilots died trying to figure something out that the pilots on the prior flight seemingly figured out at the first sign of trouble. That is just shocking to me. A toilet is broken or a windshield cracks, I get that. But bells going off, sticks shaking, pilots hand flying at a lower altitude after disabling core automated systems..that sounds like an extremely serious and rare event.

As always I must add the disclaimer that I'm no expert so maybe I'm missing something that logically explains this.

Should those pilots not be suspended etc for not turning back during that flight. Had they turned back would we be even in a thread about a disaster now?

Them turning back would have shown the plane not airworthy and maybe got a better maintenance job done etc?

Potentially

StTim wrote:

I am really not sure what you are expecting?

I would expect folks with intimate or expert knowledge in this sort of recovery operation or CVRs in general to be asking tough questions like WHY hasn't this piece of metal been found.

No one here has obvious involvement in the search for the CVR.

That is neither here nor at the bottom of an Indonesia ocean.

I am absolutely certain we want it found.

We is one thing, it's "they" that's the question.

Casting aspersions on here and expecting a response is frankly facile.

No more facile that a frankly disingenuous response.

Tristarsteve wrote:

Speaking of that notorious left AOA sensor, I found an interesting segment from NY times article "In Indonesia Lion Air Crash, Black Box Data Reveal Pilots’ Struggle to Regain Control". It reads...

...The plane that crashed on Oct. 29 had experienced days of incorrect data readings, according to Indonesian officials. In fact, before the penultimate flight, engineers had replaced one of the angle-of-attack sensors.

Why the plane recorded incorrect angle-of-attack data after the sensor had been changed is not clear. Soerjanto Tjahjono, the head of Indonesia’s National Transportation Safety Committee, said that the replacement part was not new but was “serviceable” and had certification from the F.A.A. of the United States...

full article: https://www.nytimes.com/2018/11/27/worl ... rash-.html



Curiouser...curiouser...

Why is that curious.??
They replaced the AOA probe with a serviceable part from their store. The part was a rotable, so the item in the stores had been previously removed from a B737 NG, repaired and tested and put back in the store as a serviceable component.
All serviceable components have a release form attached which is called an FAA Form 8130-3 or/and EASA form 1.
Most rotable components in an airline store are not new but repaired.

Well, since the vane's replacement was not brand new, that raised the possibility of its "imperfection". I don't mean to say a brand new item is 100% more reliable and free from defect, but refurbished/repaired items are as such because they had been either 100% defective/broken/deficient before. So, it's possible that replacement vane still had its original "imperfection" even after being repaired/improved/serviced and tested.

I don't think it's over-reaching, is it? Especially, more and more evidence seems to point to the left probe as the source of the erroneous input.

N212R wrote:

StTim wrote:

I am really not sure what you are expecting?

I would expect folks with intimate or expert knowledge in this sort of recovery operation or CVRs in general to be asking tough questions like WHY hasn't this piece of metal been found.

No one here has obvious involvement in the search for the CVR.

That is neither here nor at the bottom of an Indonesia ocean.

I am absolutely certain we want it found.

We is one thing, it's "they" that's the question.

Casting aspersions on here and expecting a response is frankly facile.

No more facile that a frankly disingenuous response.

They is the question. Without the CVR on AF crash we might have heard a very different story about cause and blame, even with all the other data.

patplan wrote:

Well, since the vane's replacement was not brand new, that raised the possibility of its "imperfection". I don't mean to say a brand new item is 100% more reliable and free from defect, but refurbished/repaired items are as such because they had been either 100% defective/broken/deficient before. So, it's possible that replacement vane still had its original "imperfection" even after being repaired/improved/serviced and tested.

I don't think it's over-reaching, is it? Especially, more and more evidence seems to point to the left probe as the source of the erroneous input.

I've changed parts that had serviceable tags with documentation saying they passed bench test, or the gripe could not be repeated in the shop. Install it, same problem comes up and the part is removed again. Lots of times the repair shop doesnt get enough detailed information, same as line mechanics who dont get enough details to make the right repairs.

I would he interested to know what the AOA sensor was removed for previously. Also interested to know what if any calibration is required when installing on the aircraft.

One of the major takeaways from this accident SHOULD be the utter stupity if the “redundancy=safety” mantra. Redundancy only works when the backup can effectively replace the faulty system AND we have confidence in the backup. The only way to have confidence in the backup when it comes to sensors is to have a backup to the backup that can be compared to both redundant sensors to determine confidence in data.

As it stands, we have sensors that provide two sides of the story, but the truth is unknowable. As soon as one lies, we can’t be sure which one is lying. We can guess (horizon seems to tell us sensor 2 is right) but that only works in clear weather during the day over level terrain.

At minimum, automatic systems should not function when either the main or backup sensor fails. They should deactivate and inform the crew. The crew can then attempt to discern which sensor is wrong and rely on the one they trust.

N212R wrote:

StTim wrote:

I am really not sure what you are expecting?

I would expect folks with intimate or expert knowledge in this sort of recovery operation or CVRs in general to be asking tough questions like WHY hasn't this piece of metal been found.

No one here has obvious involvement in the search for the CVR.

That is neither here nor at the bottom of an Indonesia ocean.

I am absolutely certain we want it found.

We is one thing, it's "they" that's the question.

Casting aspersions on here and expecting a response is frankly facile.

No more facile that a frankly disingenuous response.

These are links on news on the CVR. It's in Indonesian. You can google translate them.

In summary, search for CVR has not resumed, because they are still looking for DP 2 vessel, as regular vessel with anchor can not be used due to submarine cables and oil & gas pipelines.

https://bisnis.tempo.co/read/1150521/cvr-lion-air-jt-610-belum-ditemukan-knkt-cari-dengan-kapal-baru

https://nasional.kompas.com/read/2018/11/28/15325861/cari-cvr-lion-air-jt-610-knkt-butuh-kapal-khusus-hingga-alat-sedot-lumpur

ikramerica wrote:

As it stands, we have sensors that provide two sides of the story, but the truth is unknowable. As soon as one lies, we can’t be sure which one is lying. We can guess (horizon seems to tell us sensor 2 is right) but that only works in clear weather during the day over level terrain.

It's knowable with predictor algorithms based on flight dynamic model feed by all information available on the aircraft. Each inputs values modify the probability output of the predictor with it own probability to fit the result. If all information but a single sensor agree on a probability, the one that disagree will be almost rejected. Sadly this kind of algorithm is still not used for aircraft air data sensors.

ikramerica wrote:

At minimum, automatic systems should not function when either the main or backup sensor fails. They should deactivate and inform the crew. The crew can then attempt to discern which sensor is wrong and rely on the one they trust.

The problem is that the MCAS is not a optional automatic system. The MCAS is actually a required protection system with authority over the pilot due to the greater instability of the 373MAX compared to the previous 737 families.

PixelFlight wrote:

The problem is that the MCAS is not a optional automatic system. The MCAS is actually a required protection system with authority over the pilot due to the greater instability of the 373MAX compared to the previous 737 families.

Greater instability of different center or gravity?

patplan wrote:

Tristarsteve wrote:

Speaking of that notorious left AOA sensor, I found an interesting segment from NY times article "In Indonesia Lion Air Crash, Black Box Data Reveal Pilots’ Struggle to Regain Control". It reads...

...The plane that crashed on Oct. 29 had experienced days of incorrect data readings, according to Indonesian officials. In fact, before the penultimate flight, engineers had replaced one of the angle-of-attack sensors.

Why the plane recorded incorrect angle-of-attack data after the sensor had been changed is not clear. Soerjanto Tjahjono, the head of Indonesia’s National Transportation Safety Committee, said that the replacement part was not new but was “serviceable” and had certification from the F.A.A. of the United States...

full article: https://www.nytimes.com/2018/11/27/worl ... rash-.html



Curiouser...curiouser...

Why is that curious.??
They replaced the AOA probe with a serviceable part from their store. The part was a rotable, so the item in the stores had been previously removed from a B737 NG, repaired and tested and put back in the store as a serviceable component.
All serviceable components have a release form attached which is called an FAA Form 8130-3 or/and EASA form 1.
Most rotable components in an airline store are not new but repaired.

Well, since the vane's replacement was not brand new, that raised the possibility of its "imperfection". I don't mean to say a brand new item is 100% more reliable and free from defect, but refurbished/repaired items are as such because they had been either 100% defective/broken/deficient before. So, it's possible that replacement vane still had its original "imperfection" even after being repaired/improved/serviced and tested.

I don't think it's over-reaching, is it? Especially, more and more evidence seems to point to the left probe as the source of the erroneous input.

There should be no difference between a new and refurbished item tested to the same specs. No reason to trust the new part more than the refurbished one.

https://www.washingtonpost.com/business ... 09e739efc2

One point I found interesting, 100 pounds pressure on the yoke to hold against the down force produced by MCAS and / or stall warning?

PixelFlight wrote:

ikramerica wrote:

As it stands, we have sensors that provide two sides of the story, but the truth is unknowable. As soon as one lies, we can’t be sure which one is lying. We can guess (horizon seems to tell us sensor 2 is right) but that only works in clear weather during the day over level terrain.

It's knowable with predictor algorithms based on flight dynamic model feed by all information available on the aircraft. Each inputs values modify the probability output of the predictor with it own probability to fit the result. If all information but a single sensor agree on a probability, the one that disagree will be almost rejected. Sadly this kind of algorithm is still not used for aircraft air data sensors.

ikramerica wrote:

At minimum, automatic systems should not function when either the main or backup sensor fails. They should deactivate and inform the crew. The crew can then attempt to discern which sensor is wrong and rely on the one they trust.

The problem is that the MCAS is not a optional automatic system. The MCAS is actually a required protection system with authority over the pilot due to the greater instability of the 373MAX compared to the previous 737 families.

Optional doesn’t really matter. It can be disengaged. It means that the pilots have to know its disengaged and that the envelope of the aircraft is reduced and an emergency must be declared. A lot of system failures would have limitations on performance. Losing an engine changes the performance of an aircraft.

SimpleFlying wrote:

These are links on news on the CVR. It's in Indonesian. You can google translate them.

An integral aviation component, produced by a "western" industrial company for a Boeing airplane, whose recovery is fundamental to understanding the cause of this accident and all we get are links....in Indonesian? No one in the western news world thinks this continuing part of the story deserves press coverage?

In summary, search for CVR has not resumed, because they are still looking for DP 2 vessel, as regular vessel with anchor can not be used due to submarine cables and oil & gas pipelines.

How many ships, planes and personnel were channeled IMMEDIATELY into the M370 incident ? And here we are weeks later still trying to find a boat without an anchor?

There's something adrift here all right.

So it looks like Southwest is adding an AoA indicator to the PFD ontheir MAX aircraft. It was already available through the HUD but not the PFD. Why was it not already there in the first place?

http://bit.ly/2FOYtes

Edit: Also note that the picture is from July 2016, it must be some sort of optional software.

N212R wrote:

SimpleFlying wrote:

These are links on news on the CVR. It's in Indonesian. You can google translate them.

An integral aviation component, produced by a "western" industrial company for a Boeing airplane, whose recovery is fundamental to understanding the cause of this accident and all we get are links....in Indonesian? No one in the western news world thinks this continuing part of the story deserves press coverage?

In summary, search for CVR has not resumed, because they are still looking for DP 2 vessel, as regular vessel with anchor can not be used due to submarine cables and oil & gas pipelines.

How many ships, planes and personnel were channeled IMMEDIATELY into the M370 incident ? And here we are weeks later still trying to find a boat without an anchor?

There's something adrift here all right.

A ship holding a precise position without anchors is hardly available on short notice, only used in specialized industries. I would challenge you to find one in the USA on a short notice.

Trin wrote:

WHY would an airplane with such sensor discrepancies be allowed to (be able to) take off?
...
Now we have to get into the nitty-gritty of WHY the mx logs state that the repair work that was done to it satisfied ground tests prior to takeoff, and why AOA disagrees were not seen during their testing before the final flight.

Finn350 gave you the technical answer, but I'll just add that in these threads there's sometimes been confusion about whether maintenance was done at all, as "we're not even bothering to fix a critical error". This does not appear to be the case. Maintenance has done something and believed they did enough. Now why that wasn't enough could be due to many reasons. Maybe the world needs better measurement tests to actually see this kind of sensor works. Maybe the part they used was imperfect. Maybe the error was somewhere completely elsewhere, not in the sensor but in the systems using the sensor. Maybe the maintenance crew screwed up. Maybe information about the problem on previous flight wasn't accurate enough and the maintenance crew did not understand the full scope of problems and therefore didn't fix everything. Or something else.

Interesting. Possibility of software upgrade to prevent MCAS misbehaviour.

https://www.moneycontrol.com/news/busin ... 1.html/amp

N212R wrote:

An integral aviation component, produced by a "western" industrial company for a Boeing airplane, whose recovery is fundamental to understanding the cause of this accident and all we get are links....in Indonesian? No one in the western news world thinks this continuing part of the story deserves press coverage?

Complaining about it here is pointless. Complain to the "western media". Let us know how you get on.

N212R wrote:

How many ships, planes and personnel were channeled IMMEDIATELY into the M370 incident ? And here we are weeks later still trying to find a boat without an anchor?

There's something adrift here all right.

Totally different circumstances. Sadly we know everyone on the Lion flight was dead within minutes of it crashing, MH370 disappeared in mysterious circumstances.

The FDR was found quickly, if "they" were trying to cover something up "they" wouldn't have found it. Just because you seem to want to believe something nefarious is going on, doesn't mean it is.

klkla wrote:

PixelFlight wrote:

The problem is that the MCAS is not a optional automatic system. The MCAS is actually a required protection system with authority over the pilot due to the greater instability of the 373MAX compared to the previous 737 families.

Greater instability of different center or gravity?

The answer is the the first part of this article: https://theaircurrent.com/aviation-safe ... cas-jt610/

scbriml wrote:

Totally different circumstances. Sadly we know everyone on the Lion flight was dead within minutes of it crashing, MH370 disappeared in mysterious circumstances.

The FDR was found quickly, if "they" were trying to cover something up "they" wouldn't have found it. Just because you seem to want to believe something nefarious is going on, doesn't mean it is.

More excuses for all parties involved but one. We're now okay with "grading" the need to send the necessary search and recovery equipment based on whether anyone survived? The CVR isn't important enough to demand the right equipment in a timely manner (assuming that's actually the reason)? The WSJ reported that the search radius for the pings believed to be from the CVR was only 80 feet, and this was just days after the crash. And a month later it hasn't been found?

Because you seem to want to believe nothing nefarious is going, doesn't mean there isn't. See, two can play that game.

That the CVR has not been reported to be found should be a concern to all who are interested in a complete and fair investigation. Dismissing that concern is, frankly, repugnant in the light of this tragedy. The CVR is a critical piece to this investigation. There are parties that may not want that information to be revealed. This is not a time for excuses if you desire the truth.

the fact that the pilots had the control column full backwards but couldn't stop the airplane with minor glitches from plunging itself into the sea at high speed seem obviously wrong to me on the design side. it reminded me of the A300-600R Nagoya crash and that was 1994, more than 2 decades ago.
don't forget it's 189 lives...

MSPNWA wrote:

scbriml wrote:

Totally different circumstances. Sadly we know everyone on the Lion flight was dead within minutes of it crashing, MH370 disappeared in mysterious circumstances.

The FDR was found quickly, if "they" were trying to cover something up "they" wouldn't have found it. Just because you seem to want to believe something nefarious is going on, doesn't mean it is.

More excuses for all parties involved but one. We're now okay with "grading" the need to send the necessary search and recovery equipment based on whether anyone survived? The CVR isn't important enough to demand the right equipment in a timely manner (assuming that's actually the reason)? The WSJ reported that the search radius for the pings believed to be from the CVR was only 80 feet, and this was just days after the crash. And a month later it hasn't been found?

Because you seem to want to believe nothing nefarious is going, doesn't mean there isn't. See, two can play that game.

That the CVR has not been reported to be found should be a concern to all who are interested in a complete and fair investigation. Dismissing that concern is, frankly, repugnant in the light of this tragedy. The CVR is a critical piece to this investigation. There are parties that may not want that information to be revealed. This is not a time for excuses if you desire the truth.

Based on my business experience here, I honestly believe that nothing nefarious is going on in this case.

What is going on is just that (1) things are moving slower here, (2) most likely still negotiating with vessel owner for price, payment terms, and other things.

PixelFlight wrote:

It's knowable with predictor algorithms based on flight dynamic model feed by all information available on the aircraft. Each inputs values modify the probability output of the predictor with it own probability to fit the result. If all information but a single sensor agree on a probability, the one that disagree will be almost rejected. Sadly this kind of algorithm is still not used for aircraft air data sensors.

Advanced systems beyond steam gauges on the 737 have been layered on over time. And each layer and techno splotch probably is more or less standalone, has limited inputs, a "NEW" function output.
There is no holistic access to system input to do what you propose.
( and it is afaics not a desired function. Analysis of complex systems explodes with number of components/inputs.)

maint123 wrote:

Interesting. Possibility of software upgrade to prevent MCAS misbehaviour.

https://www.moneycontrol.com/news/busin ... 1.html/amp

The article say:
"While each 737 has two of these blade-shaped vanes [AoA], the plane's anti-stall system [MCAS] relies on data pulled from just a single vane during each flight, compared with a three-sensor "voting" system on rival Airbus jetliners."

This fully fit the Boeing and FAA EAD Unsafe Condition and fully confirm the finding by high valuable contributors on this forum. This aspect of the accident is very factual, Boeing and FAA did know this already at the publication time of the EAD, but there is not a single work about this aspect on the interim report several week after. It's out of proportion.

WIederling wrote:

PixelFlight wrote:

It's knowable with predictor algorithms based on flight dynamic model feed by all information available on the aircraft. Each inputs values modify the probability output of the predictor with it own probability to fit the result. If all information but a single sensor agree on a probability, the one that disagree will be almost rejected. Sadly this kind of algorithm is still not used for aircraft air data sensors.

Advanced systems beyond steam gauges on the 737 have been layered on over time. And each layer and techno splotch probably is more or less standalone, has limited inputs, a "NEW" function output.
There is no holistic access to system input to do what you propose.
( and it is afaics not a desired function. Analysis of complex systems explodes with number of components/inputs.)

Exactly, the 737 design is so old that it's virtually impossible. High level system sensors fusion is only possible with modern AFDX aircraft networking, but this technology is now very well implemented in all major new aircraft design: https://etr2017.sciencesconf.org/data/p ... tr2017.pdf

It a desired function. I even hope it will be a required function in the near future. The complexity of a flight dynamic predictor is not that great, every single aircraft simulator, from engineering design to pilot training, have this algorithms since decades. It's really the opposite compared to adding a quickly ill designed hidden lethal MCAS.

MSPNWA wrote:

More excuses for all parties involved but one. We're now okay with "grading" the need to send the necessary search and recovery equipment based on whether anyone survived? The CVR isn't important enough to demand the right equipment in a timely manner (assuming that's actually the reason)? The WSJ reported that the search radius for the pings believed to be from the CVR was only 80 feet, and this was just days after the crash. And a month later it hasn't been found?

Because you seem to want to believe nothing nefarious is going, doesn't mean there isn't. See, two can play that game.

That the CVR has not been reported to be found should be a concern to all who are interested in a complete and fair investigation. Dismissing that concern is, frankly, repugnant in the light of this tragedy. The CVR is a critical piece to this investigation. There are parties that may not want that information to be revealed. This is not a time for excuses if you desire the truth.

Where did I "make an excuse"?

People wanted to believe some crack-pot conspiracy when it took so long to find AF447's recorders. How did that pan out? If you think something nefarious is going on, provide some evidence to support your belief. I'll wait.

PixelFlight wrote:

The problem is that the MCAS is not a optional automatic system. The MCAS is actually a required protection system with authority over the pilot due to the greater instability of the 373MAX compared to the previous 737 families.

Pilot always has authority over MCAS, as has been discussed here several times, pilot trimming using the yoke trim switches stops MCAS trim inputs.

lanceton wrote:

the fact that the pilots had the control column full backwards but couldn't stop the airplane with minor glitches from plunging itself into the sea at high speed seem obviously wrong to me on the design side. it reminded me of the A300-600R Nagoya crash and that was 1994, more than 2 decades ago.
don't forget it's 189 lives...

How do you know they had the control column full backwards? None of the FDR traces show control column position

dragon6172 wrote:

PixelFlight wrote:

The problem is that the MCAS is not a optional automatic system. The MCAS is actually a required protection system with authority over the pilot due to the greater instability of the 373MAX compared to the previous 737 families.

Pilot always has authority over MCAS, as has been discussed here several times, pilot trimming using the yoke trim switches stops MCAS trim inputs.

It that case the MCAS is not longer a protection system. Always the same conflict: is MCAS is not a required protection authority, then the 737MAX is less safe than it predecessors as it have a reduced flight envelop that require extra training to flight without or against MCAS. Enough dead already.

N212R wrote:

No more facile that a frankly disingenuous response.

The people that are so eloquently demanding "to immediately find the CVR or else"
are apparently from the same group that being in the physical vicinity of an accident
take photos, videograph accidents while obstructing the rescue operation.

Southwest is adding new angle of attack indicators to its 737 max fleet

https://theaircurrent.com/aviation-safety/southwest-airlines-is-adding-new-angle-of-attack-indicators-to-its-737-max-fleet/

A clear signal from the largest 737 MAX operator / customer.

ferpe wrote:

fadecfault wrote:

The problem with this belief is that it would make it seem the Investigators are 1) holding back information or 2) incompetent
The reason is there are position sensors in the left and right elevators. These Elevator sensors are dual channel with one channel reporting to the Flight Data recorder. The Investigators will have seen a split if a breakout occurred and it should have been on the chart and reported.
Considering that the Leeham author didn't mention the elevator position sensors I would side with the Investigators.

Of course, the investigators and also Boeing have more information. They have 69 hours with 1790 parameters from the aircraft. We have access to 40 of those for the last hours. We lack things like pitch and roll angles among a lot of other information.

My reaction is at the same time as the counter trimming changes to short blips the pitch forces separate for the two channels for the first time during these two flights. I have since got a better schema on the pitch channel breakout mechanism, it's not a clutch, nor a no breakout or breakout mechanism.



It's here described as a progressive cam and spring-loaded roller unit which allows progressive movements between the yokes and therefore a difference in the force the force transducers register at high differences in Yoke force in the two channels. The separation can mean the two pilots both pull on the Yokes and in different directions. What's disturbing is one stays put (red = Captain i interpret it as) while the other goes significantly higher from being the follower. Then the green stays at the put level while the red goes high. When one Yoke has moved before, the other has followed in force, not now. We can explain most other traces but not this part. Strange.

At the same time the crew only counter trims for short blips, leading to full MCAS nose down trim and then they plunge. They could be in a turn and one doesn't normally trim in a turn but the separation of the traces are no explained by a turn unless the two pilots are in un-sync on the Yokes. The increased dynamic pressure to the Elevator Feel Shift Module which decides the hydraulic pressure to the Elevator Feel and Centering Unit at the elevator should be the same to both sides. It shouldn't cause the differences in forces we see IMO.

A Couple things regarding the Leeham article :
1) The Chart has Pitch force labeled as CCFORCE_PITCHCWSLOCAL_FDR and CCFORCE_PITCHCWSFOREIGN_FDR. We can not tell which CWS pitch sensor is being displayed. The captains or f/o's sensor will display as local or foreign.
This is seen in the DFCS bite as:
P CWS-LCL (LBS)
CH A CH B
and
P CWS-FGN (LBS).
CH A CH B
I have tested it and each sensor feeds the local and foreign data display.
2) You can't equate force with elevator position. You can pull the column full aft and have a 50lb split between the f/o and captain. This can happen when one pilot felt the aircraft wasn't responding to nose up command of the other pilot and pulled harder. The column won't move anymore but force on it will be greater. You also push and pull in opposite directions and one sensor will read negative pounds. I registered a 70lb split (-30/+40) when I pushed /pulled the columns with one hand on each. The Graph doesn't show one line in positive and one line in negative, so the authors suggestion that the pilots worked against each other is wrong.

keesje wrote:

Southwest is adding new angle of attack indicators to its 737 max fleet

https://theaircurrent.com/aviation-safety/southwest-airlines-is-adding-new-angle-of-attack-indicators-to-its-737-max-fleet/

A clear signal from the largest 737 MAX operator / customer.

Congratulation to Southwest for there excellent reaction and communication to improve safety, even if there unfortunately can't magically change the old 737 design. Frankly, that kind of improvement should have been pushed directly by Boeing to all operators. We have more information about Boeing possible plans from journalists than from the company itself. Depressive.

dragon6172 wrote:

Pilot always has authority over MCAS, as has been discussed here several times, pilot trimming using the yoke trim switches stops MCAS trim inputs.

For just a few seconds until it kicks in again (assuming conditions that caused it to activate are still present), no?

scbriml wrote:

For just a few seconds until it kicks in again (assuming conditions that caused it to activate are still present), no?

No, the authority is always there. Yes, MCAS will attempt to trim nose down 5 seconds after pilot trim input (assuming conditions requiring its use exist), but the authority for pilots to override it is always available.

It would be interesting to know how the MCAS "nose down" trim rate compares to the yoke trim "up" rate.

dragon6172 wrote:

scbriml wrote:

For just a few seconds until it kicks in again (assuming conditions that caused it to activate are still present), no?

No, the authority is always there. Yes, MCAS will attempt to trim nose down 5 seconds after pilot trim input (assuming conditions requiring its use exist), but the authority for pilots to override it is always available.

so you have to kick it in the shins every 5..10 seconds.

That is kind of a Tamagotchi design ( feed me, go potty, warm my belly, comb my hair, feed me, ..).

terrible.

fadecfault wrote:

ferpe wrote:

fadecfault wrote:

The problem with this belief is that it would make it seem the Investigators are 1) holding back information or 2) incompetent
The reason is there are position sensors in the left and right elevators. These Elevator sensors are dual channel with one channel reporting to the Flight Data recorder. The Investigators will have seen a split if a breakout occurred and it should have been on the chart and reported.
Considering that the Leeham author didn't mention the elevator position sensors I would side with the Investigators.

Of course, the investigators and also Boeing have more information. They have 69 hours with 1790 parameters from the aircraft. We have access to 40 of those for the last hours. We lack things like pitch and roll angles among a lot of other information.

My reaction is at the same time as the counter trimming changes to short blips the pitch forces separate for the two channels for the first time during these two flights. I have since got a better schema on the pitch channel breakout mechanism, it's not a clutch, nor a no breakout or breakout mechanism.



It's here described as a progressive cam and spring-loaded roller unit which allows progressive movements between the yokes and therefore a difference in the force the force transducers register at high differences in Yoke force in the two channels. The separation can mean the two pilots both pull on the Yokes and in different directions. What's disturbing is one stays put (red = Captain i interpret it as) while the other goes significantly higher from being the follower. Then the green stays at the put level while the red goes high. When one Yoke has moved before, the other has followed in force, not now. We can explain most other traces but not this part. Strange.

At the same time the crew only counter trims for short blips, leading to full MCAS nose down trim and then they plunge. They could be in a turn and one doesn't normally trim in a turn but the separation of the traces are no explained by a turn unless the two pilots are in un-sync on the Yokes. The increased dynamic pressure to the Elevator Feel Shift Module which decides the hydraulic pressure to the Elevator Feel and Centering Unit at the elevator should be the same to both sides. It shouldn't cause the differences in forces we see IMO.

A Couple things regarding the Leeham article :
1) The Chart has Pitch force labeled as CCFORCE_PITCHCWSLOCAL_FDR and CCFORCE_PITCHCWSFOREIGN_FDR. We can not tell which CWS pitch sensor is being displayed. The captains or f/o's sensor will display as local or foreign.
This is seen in the DFCS bite as:
P CWS-LCL (LBS)
CH A CH B
and
P CWS-FGN (LBS).
CH A CH B
I have tested it and each sensor feeds the local and foreign data display.
2) You can't equate force with elevator position. You can pull the column full aft and have a 50lb split between the f/o and captain. This can happen when one pilot felt the aircraft wasn't responding to nose up command of the other pilot and pulled harder. The column won't move anymore but force on it will be greater. You also push and pull in opposite directions and one sensor will read negative pounds. I registered a 70lb split (-30/+40) when I pushed /pulled the columns with one hand on each. The Graph doesn't show one line in positive and one line in negative, so the authors suggestion that the pilots worked against each other is wrong.

And, if breakout had occurred, surely a position trace would have been included in the initial preliminary report.

(edit, sorry, missed part of fadecfault's response to Ferpe. Not a fan of how quotes work now. Don't scroll, miss things.)