rheinwaldner wrote:

MSPNWA wrote:

mjoelnir wrote:

No other frame had in the last 30 years this rate of accidents to number of operating frames or operating hours.

False. The A320 had its first, second, and third crashes with fewer frames in service than the MAX did with its second (maybe first).

The difference is that these crashes had unrelated reasons. The MAX could be the first jet airliner ever, that crashed two times due to the same technical reason (as main contributing factor) at all.

So far, based on DATA and not SPECULATION the Max hasn't had two crashes for the same reason either. Additionally, the ET flight looks VERY different on FR data and MAY have a different root cause.

zckls04 wrote:

superbizzy73 wrote:

Help me out here (and, yes, I'm definitely ready to get flamed in this a.net world)...so, United Airlines has the exact same setup as the MAX's that crashed, and they have 23,000 +/- flight hours with the type...and they didn't crash a one of them (yes, I know they have the -9, and the aircraft that crashed were -8...they all have the same flight system. As far as I can understand, United's MCAS is set up the exact same way, with none of the extras that have been mentioned.) I wonder why United hasn't crashed a MAX?

Events don't usually happen in a uniform manner. Once you start talking about an event that happens with a very small probability, as in the case of a plane crash, you simply can't infer that because the event didn't happen in a particular subset of the sample (US flights), it is proof, or even evidence of it being meaningful in some way. That's absolutely statistically invalid. In fact in general, statistics are not that useful for gleaning information about extremely rare events; they only become useful with a large sample size of events.

Now, it may yet transpire that the circumstances of the Lion Air and Ethiopian crashes could not happen in the US, and perhaps further information will come to light that proves that. However looking purely at the statistics, there is no evidence that the MAX crashes were not US airlines is in any way significant. That's simply not what the evidence shows.

Maybe the MCAS system is flawed, but there is a very distinct procedure to get the aircraft to fly properly if a system seems to not be working right as far as I understand, and it's unfortunately pretty obvious that the procedures were not followed.

Indeed. The question is whether that procedure is comprehensive enough, whether it was communicated properly to the pilots, and whether the problem ought to arise in the first place.

Your post reminded me of British Airways 38. Dozens of 777-200ERs were flying around with an improperly design fuel oil heating exchange. I'm willing to bet a pretty penny we've had dozens of 777-200ERs with uncommanded rollback of engines that were directly related to the FOHE prior to Speedbird 38, but was never able to completely isolate the root cause until Speedbird 38..

Sometimes certain unique conditions must happen before it issues show up.

casinterest wrote:

Will people come up with bullshit tests for systems unaffected?
Or will they all work to re-certify based on what is known?
Multiple fixes documentation changes, and training requirements have been made for faulty sensors data, with no redundancy, feeding an automated system that if left undiagnosed by pilots for 30-50 seconds can result in a crash?

All the other changes from NG to MAX would need some scrutiny too. trust has been trashed.

osiris30 wrote:

So far, based on DATA and not SPECULATION the Max hasn't had two crashes for the same reason either. Additionally, the ET flight looks VERY different on FR data and MAY have a different root cause.

MAX had 2 crashes with unknown cause and similar behavior in the path to that crash.
Causes are still unknown. Boeing is busily fixing elements that "promoted" a data integrity error into a crash.
Root cause is still open and involved parties seem to meander around finding that cause.

rheinwaldner wrote:

MSPNWA wrote:

mjoelnir wrote:

The MAX could be the first jet airliner ever, that crashed two times due to the same technical reason (as main contributing factor) at all.

I'm no history expert but at least the Comet comes to mind. And I'd be surprised if it were the only one.

ILNFlyer wrote:

This has certainly left both the FAA and Boeing with black eyes, and if guilty, rightly so. I would be interested in knowing how Airbus handles a similar system.

The A320 does not need an MCAS. It has fly by wire too.

osiris30 wrote:

rheinwaldner wrote:

The MAX could be the first jet airliner ever, that crashed two times due to the same technical reason (as main contributing factor) at all.

So far, based on DATA and not SPECULATION the Max hasn't had two crashes for the same reason either.

Two times the end came when the stab trim reached the nose-down extreme. That is fact. What other data do you have? There is none with equal quality.

Also, dont forget, the trim was surely not brought into that position by the pilots. It must have been "the machine". In two cases. In 2018/19. Unprecedented.

Hi,

Just came across this article. Media sensationalism aside this is crazy.

https://www.google.com/amp/s/www.cnbc.c ... rport.html

a380900 wrote:

ILNFlyer wrote:

This has certainly left both the FAA and Boeing with black eyes, and if guilty, rightly so. I would be interested in knowing how Airbus handles a similar system.

The A320 does not need an MCAS. It has fly by wire too.

Could any A320 pilots inform us whether the Flight Envelope Protection would push the nose down upon detecting a stall?

Bradin wrote:

Could any A320 pilots inform us whether the Flight Envelope Protection would push the nose down upon detecting a stall?

Equally important would be whether Airbus FBW would ever correct a percieved stall based on a single set of sensor data.

My understanding is they rely on input from three AoA sensors as a failsafe.

osiris30 wrote:

So far, based on DATA and not SPECULATION the Max hasn't had two crashes for the same reason either. Additionally, the ET flight looks VERY different on FR data and MAY have a different root cause.

Just remind me; what was it Canada said? Something about significant data from satellites and not just FR24?

As it happens, after a shaky start, as each day passes I am beginning to appreciate your pro-Boeing contributions more than the perpetual smokescreens thrown up by some others on these forums. You show intelligence, and reasonableness, and that is quite enough of me blowing smoke up your exhaust pipe.

Could it be that these HUGE differences that you perceive from FR24 data are down to ADD being at 7,200ft?
Until you identify these {insert adjective of choice} differences, I am more inclined to believe the Canadian Transportation Minister Marc Garneau who spoke only of similarities.

I accept you are right that there is a possibility the two crashes are from different root causes, maybe with a common helping of pilot error - not because it was LionAir, or ET, but because pilot error is the #1 cause of crashes worldwide, yeah, even in America.

If that turns out to be the case, then so be it, but at least this whole debacle has highlighted a number of other issues that really needed to be dragged into the light.

And it could even turn out that correcting the flaws in MCAS is the very least of Boeing's worries.

rheinwaldner wrote:

osiris30 wrote:

rheinwaldner wrote:

The MAX could be the first jet airliner ever, that crashed two times due to the same technical reason (as main contributing factor) at all.

So far, based on DATA and not SPECULATION the Max hasn't had two crashes for the same reason either.

Two times the end came when the stab trim reached the nose-down extreme. That is fact. What other data do you have? There is none with equal quality.

Also, dont forget, the trim was surely not brought into that position by the pilots. It must have been "the machine". In two cases. In 2018/19. Unprecedented.

Source on "trim reached the nose down extreme" please. I have seen ET jackscrew was trimmed nose down. I have seen 0 articles that say it was trimmed to max extent. If you have please provide the source.

Don't know if anybody's seen this yet, but a WN Max 8 declared an emergency on it's way from Orlando to Victorville on a ferry flight due to "engine" trouble and turned around back to MCO:

https://www.cnn.com/2019/03/26/us/boein ... index.html

SheikhDjibouti wrote:

osiris30 wrote:

So far, based on DATA and not SPECULATION the Max hasn't had two crashes for the same reason either. Additionally, the ET flight looks VERY different on FR data and MAY have a different root cause.

Just remind me; what was it Canada said? Something about significant data from satellites and not just FR24?

As it happens, after a shaky start, as each day passes I am beginning to appreciate your pro-Boeing contributions more than the perpetual smokescreens thrown up by some others on these forums. You show intelligence, and reasonableness, and that is quite enough of me blowing smoke up your exhaust pipe.

Could it be that these HUGE differences that you perceive from FR24 data are down to ADD being at 7,200ft?
Until you identify these {insert adjective of choice} differences, I am more inclined to believe the Canadian Transportation Minister Marc Garneau who spoke only of similarities.

I accept you are right that there is a possibility the two crashes are from different root causes, maybe with a common helping of pilot error - not because it was LionAir, or ET, but because pilot error is the #1 cause of crashes worldwide, yeah, even in America.

If that turns out to be the case, then so be it, but at least this whole debacle has highlighted a number of other issues that really needed to be dragged into the light.

And it could even turn out that correcting the flaws in MCAS is the very least of Boeing's worries.

If you read the ET thread I explained that the sat data is adsb and ads-b doesn't have any data on mcas. It will show altitude variations, speed, etc. It won't speak to control deflections systems etc. I have provided a scenario where you needn't have MCAS to produce similar flight patterns.

As for pro-Boeing;. I admit to having a preference for Boeing equipment. But with said preference disclosed I have always extolled the engineering and safety of both manufacturers when talking to lay people. My beefs with Airbus have always been their business model and their crazy insistence on the 380 which I saw as a bad idea from day one (and eventually the market proved that assessment correct).

I have NEVER wished Ill on Airbus as an entity, their people or their products. I want a strong and healthy Airbus to be there to drive my preferred manufacturer to better and better products. Monopoly hurts us all.

My defense of the max is less a defense of the aircraft itself and more me pointing out (several hundred times now) that we have no idea if MCAS had ANYTHING to do with ET. Focusing on it solely could be deadly because what if the issue is far bigger than MCAS. Even if the issue is MCAS, I firmly believe blaming it on one system is burying another couple of much larger and ultimately MUCH more important questions that apply to ALL manufacturers.

1) certification processes and more importantly IMHO
2) human to machine interfaces (and area of passion for me my entire career).

The second is not given the resources needed in much of life and yet is increasingly more important as every day passes and automation increases


Edit:. Autocorrect ate my words...

rj777 wrote:

Don't know if anybody's seen this yet, but a WN Max 8 declared an emergency on it's way from Orlando to Victorville on a ferry flight due to "engine" trouble and turned around back to MCO:

https://www.cnn.com/2019/03/26/us/boein ... index.html

Exactly what Boeing needs (NOT): more issues with the 737-MAX. One more incident and the flying public demands all MAX-es go to the shredder.

a380900 wrote:

rheinwaldner wrote:

MSPNWA wrote:

I'm no history expert but at least the Comet comes to mind. And I'd be surprised if it were the only one.

it's not even the first design flaw in the 737 that caused multiple crashes. the rudder hardover issues brought down like 3 737 classics

rj777 wrote:

Don't know if anybody's seen this yet, but a WN Max 8 declared an emergency on it's way from Orlando to Victorville on a ferry flight due to "engine" trouble and turned around back to MCO:

https://www.cnn.com/2019/03/26/us/boein ... index.html

At this point, I suggest that Boeing calls the Vatican and ask to send their best exorcist.

CLTRampRat wrote:

Hi,

Just came across this article. Media sensationalism aside this is crazy.

https://www.google.com/amp/s/www.cnbc.c ... rport.html

Stocks move 1-2% on impulse reactions to non-news all the time.
BA stock and the business networks have been viewing this event as a pretty straightforward "software fix".
They don't seem to think this will get drawn out, or that another shoe is about to drop.
So any story that gives investors a chance to reconsider, even if it has nothing to do with MCAS or the grounding, is interesting to say the least.

osiris30 wrote:

SheikhDjibouti wrote:

osiris30 wrote:

So far, based on DATA and not SPECULATION the Max hasn't had two crashes for the same reason either. Additionally, the ET flight looks VERY different on FR data and MAY have a different root cause.

Just remind me; what was it Canada said? Something about significant data from satellites and not just FR24?

As it happens, after a shaky start, as each day passes I am beginning to appreciate your pro-Boeing contributions more than the perpetual smokescreens thrown up by some others on these forums. You show intelligence, and reasonableness, and that is quite enough of me blowing smoke up your exhaust pipe.

Could it be that these HUGE differences that you perceive from FR24 data are down to ADD being at 7,200ft?
Until you identify these {insert adjective of choice} differences, I am more inclined to believe the Canadian Transportation Minister Marc Garneau who spoke only of similarities.

I accept you are right that there is a possibility the two crashes are from different root causes, maybe with a common helping of pilot error - not because it was LionAir, or ET, but because pilot error is the #1 cause of crashes worldwide, yeah, even in America.

If that turns out to be the case, then so be it, but at least this whole debacle has highlighted a number of other issues that really needed to be dragged into the light.

And it could even turn out that correcting the flaws in MCAS is the very least of Boeing's worries.

If you read the ET thread I explained that the sat data is adsb and ads-b doesn't have any data on mcas. It will show altitude variations, speed, etc. It won't speak to control deflections systems etc. I have provided a scenario where you needn't have MCAS to produce similar flight patterns.

As for pro-Boeing;. I admit to having a preference for Boeing equipment. But with said preference disclosed I have always extolled the engineering and safety of both manufacturers when talking to lay people. My beefs with Airbus have always been their business model and their crazy insistence on the 380 which I saw as a bad idea from day one (and eventually the market proved that assessment correct).

I have NEVER wished Ill on Airbus as an entity, their people or their products. I want a strong and healthy Airbus to be there to drive my preferred manufacturer to better and better products. Monopoly hurts us all.

My defense of the max is less a defense of the aircraft itself and more me pointing out (several hundred times now) that we have no idea if MCAS had ANYTHING to do with ET. Focusing on it solely could be deadly because what if the issue is far bigger than MCAS. Even if the issue is MCAS, I firmly believe blaming it on one system is burying another couple of much larger and ultimately MUCH more important questions that apply to ALL manufacturers.

1) certification processes and more importantly IMHO
2) human to machine interfaces (and area of passion for me my entire career).

The second is not given the resources needed in much of life and yet is increasingly more important as every day passes and automation increases


Edit:. Autocorrect ate my words...

I agree about the process issue. The MCAS bug should have been picked up in testing and certification. How did that go wrong?

osiris30 wrote:

My defense of the max is less a defense of the aircraft itself and more me pointing out (several hundred times now) that we have no idea if MCAS had ANYTHING to do with ET.

We don't, but Boeing seems to be pretty certain of that. I mean, they already came up with a fix, and just waitng for FAA to green light the plane back into the skies. No need to wait for the official investigation to be completed...

a380900 wrote:

rheinwaldner wrote:

MSPNWA wrote:

I'm no history expert but at least the Comet comes to mind. And I'd be surprised if it were the only one.

The DC-10? There are lots of examples if you look back far enough. But those were half a century ago.

rj777 wrote:

Don't know if anybody's seen this yet, but a WN Max 8 declared an emergency on it's way from Orlando to Victorville on a ferry flight due to "engine" trouble and turned around back to MCO:

Seems unrelated though. Still not brilliant timing.

ArgentoSystems wrote:

osiris30 wrote:

My defense of the max is less a defense of the aircraft itself and more me pointing out (several hundred times now) that we have no idea if MCAS had ANYTHING to do with ET.

We don't, but Boeing seems to be pretty certain of that. I mean, they already came up with a fix, and just waitng for FAA to green light the plane back into the skies. No need to wait for the official investigation to be completed...

That fix was announced BEFORE the ET flight crashed. It was based on the early FDR data from the Lion crash.

osiris30 wrote:

That fix was announced BEFORE the ET flight crashed. It was based on the early FDR data from the Lion crash.

Right, but somehow we are made to believe that FAA will lift the ban upon approval of the fix.

Perhaps one lesson for he 737MAX for Boeing is the MD-11. The MD-11 has a serious problem with its horizontal stabilizer design that requires careful flying procedures, in particular takeoffs and landings, especially in crosswinds. With tech adjustments, improved training, careful freight loading, its still a major workhorse for FedEx and UPS.

ArgentoSystems wrote:

osiris30 wrote:

That fix was announced BEFORE the ET flight crashed. It was based on the early FDR data from the Lion crash.

Right, but somehow we are made to believe that FAA will lift the ban upon approval of the fix.

The FAA has no data that anyone else doesn't have about the ET crash, and the banned it before the FDR and CVR were read. If you will recall the FAA was ordered to ground the type by the President. I leave it to you if you trust his decision making and judgments, but he ordered them to do it, and I don't believe they had planned to. Same said President appears to have pressured Canada into making a similar move based on his own press conference. True, not true, who knows. But if the FAA didn't want to ground it and can use a Boeing fix to get Trump to let them unground it, it doesn't mean the two are related. Let's just wait and see what the FDR and CVR say about ET. Honestly, the best news for Boeing in the long term would be that the issue WAS MCAS. That would mean once that single fix is approved by the relevant agencies they are green light again. If it is something else more sinister or deeper in the system that could lead to much more pain for them.

MCAS software fix under evaluation by FAA since January 21

Seattle Times article: https://www.seattletimes.com/business/b ... ian-crash/

"Acting Federal Aviation Administration chief Daniel Elwell will tell a Senate hearing Wednesday that “Boeing submitted … to the FAA for certification” its proposed flight-control software enhancement for the 737 MAX on Jan. 21, according to a copy of his prepared remarks obtained by The Seattle Times. That’s nearly seven weeks before the fatal crash of Ethiopian Airlines Flight 302 that killed 157 people."

Other interesting facts:
1/21 was 5 days before the government shutdown ended.
Flight tests included "sustained flight with the angle of attack high for a long period of time; steep turn maneuvering; MCAS activation; and introduction of angle of attack errors"
One flight test was on 3/12, the day before ET 302.
Final software submission expected end of this week.

osiris30 wrote:

The FAA has no data

All true, but really besides the point. Look at the stock price, and news circulated about the fix.

CLTRampRat wrote:

Hi,

Just came across this article. Media sensationalism aside this is crazy.

https://www.google.com/amp/s/www.cnbc.c ... rport.html

It's not that crazy. The engines on the -MAX are fine (other than the obvious issues). IFSDs are expected in a new engine type and they haven't been a major issue in the -MAX family. Buuuuuut, the timing is pretty horrible and it looks really bad to the flying public.

mzlin wrote:

Other interesting facts:
1/21 was 5 days before the government shutdown ended.
Flight tests included "sustained flight with the angle of attack high for a long period of time; steep turn maneuvering; MCAS activation; and introduction of angle of attack errors"
One flight test was on 3/12, the day before ET 302.
Final software submission expected end of this week.

I think the article raises wrong question. "the question of whether it could have been approved and deployed to the worldwide MAX fleet earlier, before the Ethiopian accident." That is irrelevant. The question everyone should be asking why neither Boeing nor FAA insisted upon immediate grounding when they knew of a critical s/w defect so long ago?

ArgentoSystems wrote:

mzlin wrote:

Other interesting facts:
1/21 was 5 days before the government shutdown ended.
Flight tests included "sustained flight with the angle of attack high for a long period of time; steep turn maneuvering; MCAS activation; and introduction of angle of attack errors"
One flight test was on 3/12, the day before ET 302.
Final software submission expected end of this week.

I think the article raises wrong question. "the question of whether it could have been approved and deployed to the worldwide MAX fleet earlier, before the Ethiopian accident." That is irrelevant. The question everyone should be asking why neither Boeing nor FAA insisted upon immediate grounding when they knew of a critical s/w defect so long ago?

Well; do you know the failure rate for the AoA sensors? (I don't know I am asking). The answer to that question will likely contain the answer to your question. If they have a very low failure rate, where it is reasonable to expect there to not be another incident triggered by the same thing, especially in light of the bulletin going out addressing what to do if it DOES happen, then it is perfectly safe to not ground anything. This is about risk management. If we want to talk about absolutes, then every time a plane crashes the type should be grounded until the final report is released and all corrective actions are taken. That is clearly not a reasonable position to take nor am I advocating it. However, if you aren't going to take that position, then it comes down to risk management, which requires data that few (to none) of us on this board have.

It is easy to sit here and discuss things as cut and dry, but let me ask you a question (again an honest one): What if the ET findings say this had nothing to do with MCAS. *IF* that were the case, would you say the fleet should be grounded at present?

Bradin wrote:

Via New York Times: In Test of Boeing Jet, Pilots Had 40 Seconds to Fix Error

https://www.nytimes.com/2019/03/25/busi ... error.html

Fair Use Excerpt:

During flight simulations recreating the problems with the doomed Lion Air plane, pilots discovered that they had less than 40 seconds to override an automated system on Boeing’s new jets and avert disaster.

Also of interest, it reads like there is a logic error in the software.

In the current design, the system engages for 10 seconds at a time, with five-second pauses in between. Under conditions similar to the Lion Air flight, three engagements over just 40 seconds, including pauses, would send the plane into an unrecoverable dive, the two people involved in the testing said.

For people that are running into the paywall, here is the full article posted on The Strait Times.

https://www.straitstimes.com/world/unit ... n-lion-air

osiris30 wrote:

If we want to talk about absolutes, then every time a plane crashes the type should be grounded until the final report is released and all corrective actions are taken.

No, that does not make sense. Even without any crashes, if you know of a FIXABLE serious defect that is likely to cause fatal loss, no matter how low probability, the planes should be grounded.

When any plane crash yes, initially you don't know the reason. Could be a bomb, could be drunk pilot. Then initially grounding is not warranted.

AoA sensor apparently fails all the time.

Jamie514 wrote:

Bradin wrote:

Could any A320 pilots inform us whether the Flight Envelope Protection would push the nose down upon detecting a stall?

Equally important would be whether Airbus FBW would ever correct a percieved stall based on a single set of sensor data.

My understanding is they rely on input from three AoA sensors as a failsafe.

Bradin wrote:

a380900 wrote:

ILNFlyer wrote:

This has certainly left both the FAA and Boeing with black eyes, and if guilty, rightly so. I would be interested in knowing how Airbus handles a similar system.

The A320 does not need an MCAS. It has fly by wire too.

Could any A320 pilots inform us whether the Flight Envelope Protection would push the nose down upon detecting a stall?

In short, yes, it would. The protection you are referencing is the angle of attack protection.

To give a simple explanation of the system, at the bottom of the speed tape is an amber line followed by amber/black tape, followed by red and black tape. It starts from the top of the amber line, this is called αVLS (the minimum allowed speed for this weight/config etc...) if you continue to fall below αVLS, then you will enter the amber/black tape section, this section is known as VαPROT. Once you enter this section, the THS is frozen in position and "ALPHA FLOOR" protection will be automatically engaged by the aircraft, this is basically TOGA thrust setting regardless of how you've set the thrust. Once you drop all the way down the amber and black speed tape, you will hit what is known as VαMAX (the start of the red and black tape section), this is the point at which the aeroplane will start to nose down and reduced the pitch authority of the pilot, the aeroplane will maintain VαMAX and will stabilise at that speed, which is close to, but not less than the 1G stall speed. Should the pilot release the sidestick pressure, the aeroplane will automatically nose down to the point where it will regain VαPROT speed and will stay there, it also limits nose up trim in this configuration, with only nose down trim remaining available.

So the aeroplane will not fall from the sky unless something has gone very wrong with the computers, even in alternate law (with reduced protections) there is still low speed stability built in, where a progressive nose down is ordered by the aeroplane to stop you from falling past VLS and VSW (stall warning speed)

Hope this answered your question without being too complicated!



(A320 F/O)

danirich26 wrote:

Jamie514 wrote:

Bradin wrote:

Could any A320 pilots inform us whether the Flight Envelope Protection would push the nose down upon detecting a stall?

Equally important would be whether Airbus FBW would ever correct a percieved stall based on a single set of sensor data.

My understanding is they rely on input from three AoA sensors as a failsafe.

Bradin wrote:

a380900 wrote:

The A320 does not need an MCAS. It has fly by wire too.

Could any A320 pilots inform us whether the Flight Envelope Protection would push the nose down upon detecting a stall?

In short, yes, it would. The protection you are referencing is the angle of attack protection.

To give a simple explanation of the system, at the bottom of the speed tape is an amber line followed by amber/black tape, followed by red and black tape. It starts from the top of the amber line, this is called αVLS (the minimum allowed speed for this weight/config etc...) if you continue to fall below αVLS, then you will enter the amber/black tape section, this section is known as VαPROT. Once you enter this section, the THS is frozen in position and "ALPHA FLOOR" protection will be automatically engaged by the aircraft, this is basically TOGA thrust setting regardless of how you've set the thrust. Once you drop all the way down the amber and black speed tape, you will hit what is known as VαMAX (the start of the red and black tape section), this is the point at which the aeroplane will start to nose down and reduced the pitch authority of the pilot, the aeroplane will maintain VαMAX and will stabilise at that speed, which is close to, but not less than the 1G stall speed. Should the pilot release the sidestick pressure, the aeroplane will automatically nose down to the point where it will regain VαPROT speed and will stay there, it also limits nose up trim in this configuration, with only nose down trim remaining available.

So the aeroplane will not fall from the sky unless something has gone very wrong with the computers, even in alternate law (with reduced protections) there is still low speed stability built in, where a progressive nose down is ordered by the aeroplane to stop you from falling past VLS and VSW (stall warning speed)

Hope this answered your question without being too complicated!



(A320 F/O)

Thank you danirich26! Very informative!

Based on that reading, it sounds like there is a MCAS-like device or functionality within A320s.

ArgentoSystems wrote:

osiris30 wrote:

If we want to talk about absolutes, then every time a plane crashes the type should be grounded until the final report is released and all corrective actions are taken.

No, that does not make sense. Even without any crashes, if you know of a FIXABLE serious defect that is likely to cause fatal loss, no matter how low probability, the planes should be grounded.

When any plane crash yes, initially you don't know the reason. Could be a bomb, could be drunk pilot. Then initially grounding is not warranted.

AoA sensor apparently fails all the time.

Your wording nails it: LIKELY. Likely is why I said you need to look at the data. How LIKELY is it that:

1) an AoA sensor fails
2) it is the one being used (50/50 chance)
3) the pilots don't or can't counteract

When you feed all that data into a grid you get a number. There is a threshold maintained by the cert authorities. If the value is lower than the threshold it flies. It is that simple.

This is basic risk management stuff.

danirich26 wrote:

Jamie514 wrote:

Bradin wrote:

Could any A320 pilots inform us whether the Flight Envelope Protection would push the nose down upon detecting a stall?

Equally important would be whether Airbus FBW would ever correct a percieved stall based on a single set of sensor data.

My understanding is they rely on input from three AoA sensors as a failsafe.

Bradin wrote:

a380900 wrote:

The A320 does not need an MCAS. It has fly by wire too.

Could any A320 pilots inform us whether the Flight Envelope Protection would push the nose down upon detecting a stall?

In short, yes, it would. The protection you are referencing is the angle of attack protection.

To give a simple explanation of the system, at the bottom of the speed tape is an amber line followed by amber/black tape, followed by red and black tape. It starts from the top of the amber line, this is called αVLS (the minimum allowed speed for this weight/config etc...) if you continue to fall below αVLS, then you will enter the amber/black tape section, this section is known as VαPROT. Once you enter this section, the THS is frozen in position and "ALPHA FLOOR" protection will be automatically engaged by the aircraft, this is basically TOGA thrust setting regardless of how you've set the thrust. Once you drop all the way down the amber and black speed tape, you will hit what is known as VαMAX (the start of the red and black tape section), this is the point at which the aeroplane will start to nose down and reduced the pitch authority of the pilot, the aeroplane will maintain VαMAX and will stabilise at that speed, which is close to, but not less than the 1G stall speed. Should the pilot release the sidestick pressure, the aeroplane will automatically nose down to the point where it will regain VαPROT speed and will stay there, it also limits nose up trim in this configuration, with only nose down trim remaining available.

So the aeroplane will not fall from the sky unless something has gone very wrong with the computers, even in alternate law (with reduced protections) there is still low speed stability built in, where a progressive nose down is ordered by the aeroplane to stop you from falling past VLS and VSW (stall warning speed)

Hope this answered your question without being too complicated!



(A320 F/O)

Big difference is that the Airbus limits the elevator movement and does not trim the plane to counter maximum elevator movement. I think this is important to understand the big difference between the 2 systems.

seahawk wrote:

danirich26 wrote:

Jamie514 wrote:

Equally important would be whether Airbus FBW would ever correct a percieved stall based on a single set of sensor data.

My understanding is they rely on input from three AoA sensors as a failsafe.

Bradin wrote:

Could any A320 pilots inform us whether the Flight Envelope Protection would push the nose down upon detecting a stall?

In short, yes, it would. The protection you are referencing is the angle of attack protection.

To give a simple explanation of the system, at the bottom of the speed tape is an amber line followed by amber/black tape, followed by red and black tape. It starts from the top of the amber line, this is called αVLS (the minimum allowed speed for this weight/config etc...) if you continue to fall below αVLS, then you will enter the amber/black tape section, this section is known as VαPROT. Once you enter this section, the THS is frozen in position and "ALPHA FLOOR" protection will be automatically engaged by the aircraft, this is basically TOGA thrust setting regardless of how you've set the thrust. Once you drop all the way down the amber and black speed tape, you will hit what is known as VαMAX (the start of the red and black tape section), this is the point at which the aeroplane will start to nose down and reduced the pitch authority of the pilot, the aeroplane will maintain VαMAX and will stabilise at that speed, which is close to, but not less than the 1G stall speed. Should the pilot release the sidestick pressure, the aeroplane will automatically nose down to the point where it will regain VαPROT speed and will stay there, it also limits nose up trim in this configuration, with only nose down trim remaining available.

So the aeroplane will not fall from the sky unless something has gone very wrong with the computers, even in alternate law (with reduced protections) there is still low speed stability built in, where a progressive nose down is ordered by the aeroplane to stop you from falling past VLS and VSW (stall warning speed)

Hope this answered your question without being too complicated!



(A320 F/O)

Big difference is that the Airbus limits the elevator movement and does not trim the plane to counter maximum elevator movement. I think this is important to understand the big difference between the 2 systems.

Plus even more important: the geometry of the A320s does not require it.

rheinwaldner wrote:

seahawk wrote:

danirich26 wrote:

In short, yes, it would. The protection you are referencing is the angle of attack protection.

To give a simple explanation of the system, at the bottom of the speed tape is an amber line followed by amber/black tape, followed by red and black tape. It starts from the top of the amber line, this is called αVLS (the minimum allowed speed for this weight/config etc...) if you continue to fall below αVLS, then you will enter the amber/black tape section, this section is known as VαPROT. Once you enter this section, the THS is frozen in position and "ALPHA FLOOR" protection will be automatically engaged by the aircraft, this is basically TOGA thrust setting regardless of how you've set the thrust. Once you drop all the way down the amber and black speed tape, you will hit what is known as VαMAX (the start of the red and black tape section), this is the point at which the aeroplane will start to nose down and reduced the pitch authority of the pilot, the aeroplane will maintain VαMAX and will stabilise at that speed, which is close to, but not less than the 1G stall speed. Should the pilot release the sidestick pressure, the aeroplane will automatically nose down to the point where it will regain VαPROT speed and will stay there, it also limits nose up trim in this configuration, with only nose down trim remaining available.

So the aeroplane will not fall from the sky unless something has gone very wrong with the computers, even in alternate law (with reduced protections) there is still low speed stability built in, where a progressive nose down is ordered by the aeroplane to stop you from falling past VLS and VSW (stall warning speed)

Hope this answered your question without being too complicated!



(A320 F/O)

Big difference is that the Airbus limits the elevator movement and does not trim the plane to counter maximum elevator movement. I think this is important to understand the big difference between the 2 systems.

Plus even more important: the geometry of the A320s does not require it.

And most important, in the A320 each redundant flight computers compare no less than 3 AoA sensors, instead of the MCAS command executed in manual flight mode by a single CPU from a single flight computer that blindly fully trust a single AoA sensor !

seahawk wrote:

danirich26 wrote:

Jamie514 wrote:

Equally important would be whether Airbus FBW would ever correct a percieved stall based on a single set of sensor data.

My understanding is they rely on input from three AoA sensors as a failsafe.

Bradin wrote:

Could any A320 pilots inform us whether the Flight Envelope Protection would push the nose down upon detecting a stall?

In short, yes, it would. The protection you are referencing is the angle of attack protection.

To give a simple explanation of the system, at the bottom of the speed tape is an amber line followed by amber/black tape, followed by red and black tape. It starts from the top of the amber line, this is called αVLS (the minimum allowed speed for this weight/config etc...) if you continue to fall below αVLS, then you will enter the amber/black tape section, this section is known as VαPROT. Once you enter this section, the THS is frozen in position and "ALPHA FLOOR" protection will be automatically engaged by the aircraft, this is basically TOGA thrust setting regardless of how you've set the thrust. Once you drop all the way down the amber and black speed tape, you will hit what is known as VαMAX (the start of the red and black tape section), this is the point at which the aeroplane will start to nose down and reduced the pitch authority of the pilot, the aeroplane will maintain VαMAX and will stabilise at that speed, which is close to, but not less than the 1G stall speed. Should the pilot release the sidestick pressure, the aeroplane will automatically nose down to the point where it will regain VαPROT speed and will stay there, it also limits nose up trim in this configuration, with only nose down trim remaining available.

So the aeroplane will not fall from the sky unless something has gone very wrong with the computers, even in alternate law (with reduced protections) there is still low speed stability built in, where a progressive nose down is ordered by the aeroplane to stop you from falling past VLS and VSW (stall warning speed)

Hope this answered your question without being too complicated!



(A320 F/O)

Big difference is that the Airbus limits the elevator movement and does not trim the plane to counter maximum elevator movement. I think this is important to understand the big difference between the 2 systems.

Both can be catastrophic if enough things go wrong. The 737 uses the stab trim as it doesn't have autopilot forcers on the elevator only on the stabiliser. It can change the feel and trim to maintain speed stability. The 737 is design so that elevator movement can counter any miss-trim through its normal flight envelope. However, all 737s have a corner case where you must use nose up trip at very high air speeds (supposedly >>VMO) to get positive pitch up. This is because the hyraulics cannot force the elevator through the full range of travel in these areas.

osiris30 wrote:

My defense of the max is less a defense of the aircraft itself and more me pointing out (several hundred times now) that we have no idea if MCAS had ANYTHING to do with ET. Focusing on it solely could be deadly because what if the issue is far bigger than MCAS.

Given the similarity of control problems experienced by both crews of the crashed aircraft, I would say it is reasonable to focus on pitch stability and trim (inc MCAS). In particular I would like to hear from Boeing why they did not highlight the pitch problem to make crews aware that this aircraft had a vice of which one one needed to be wary.

If redesigning the pitch control system would remove the vice (and make MCAS redundant) I submit that is what should be stipulated by FAA - always assuming that FAA's primary interest is in safety..

SheikhDjibouti wrote:

osiris30 wrote:

So far, based on DATA and not SPECULATION the Max hasn't had two crashes for the same reason either. Additionally, the ET flight looks VERY different on FR data and MAY have a different root cause.

Just remind me; what was it Canada said? Something about significant data from satellites and not just FR24?

There are only a few sources of satellite data that could be used. 1. ADSB data 2. ACARS or similar. The ADSB data will be exactly the same data the FR uses. The difference is that you are using satellites in place of ground receivers, so you may have more data points, especially in the terminal phase of the descent. ACARS type data would show messages from other computers on the aircraft, potentially including MTC flags. All of this would be very useful in helping to ascertain the probable cause and sequence of events.

As it happens, after a shaky start, as each day passes I am beginning to appreciate your pro-Boeing contributions more than the perpetual smokescreens thrown up by some others on these forums. You show intelligence, and reasonableness, and that is quite enough of me blowing smoke up your exhaust pipe.

Could it be that these HUGE differences that you perceive from FR24 data are down to ADD being at 7,200ft?
Until you identify these {insert adjective of choice} differences, I am more inclined to believe the Canadian Transportation Minister Marc Garneau who spoke only of similarities.

Most likely the differences in flight path will come down to different reactions by the flight crew in the face of the unknown. Looking at the DFDR traces the Indonesians have published show that even the two different crew members reacted differently. Of course until we see information from the DFDR on the Ethiopian flight we won't know the precipitating cause.

I accept you are right that there is a possibility the two crashes are from different root causes, maybe with a common helping of pilot error - not because it was LionAir, or ET, but because pilot error is the #1 cause of crashes worldwide, yeah, even in America.

If that turns out to be the case, then so be it, but at least this whole debacle has highlighted a number of other issues that really needed to be dragged into the light.

And it could even turn out that correcting the flaws in MCAS is the very least of Boeing's worries.

Unfortunately, many 'pilot error' crashes are really a result of design flaws and features, either in the aircraft and/or in the training regime. You should never hear "What is the aircraft doing?" In fact in the case of the 737 all of the Disagree information may only serve to hinder what was the appropriate response.

767333ER wrote:

superbizzy73 wrote:

trex8 wrote:

Well we know the LionAr crash had AoA sensor issues. If no UA plane had one maybe none ever had the Mcas kick in.

40 seconds to fix the problem with likely speed, altitude, terrain warnings blaring away? And the Lionair crew had no knowledge of the existence of Mcas. Yes an excellent pilot may well have been able to sort it out (or if you had a 3rd pilot on hand like flight of the Lionair plane the evening before to probably notice that trim wheel turning like crazy and help stop it). But OEMs of mass produced commercial airliners should not be building aircraft which can only be handled by test pilots! My Honda sedan shouldnt need Formula1 skills to drive on a public road.
https://www.nytimes.com/2019/03/25/busi ... error.html

Thank you for the reply. I agree with you 100% about the Honda comment. It seems to me that we are unfortunately becoming more and more dependent on technology, and it looks like it's a crutch that won't go away anytime soon. I guess I can say I'm old enough to miss that analog world.

2 things you’re missing:

First, you’re essentially arguing as many do that rogue MCAS and and should be treated like runaway trim and yet that’s a general assumption that is not true. The MCAS trim can be interrupted and overridden, but as soon as you stop counteracting it, unlike STS, it resumes. Totally different animal than runaway trim. Even if it is to be considered as runaway trim, I don’t myself remember any instance of runaway trim happening that low to the ground. Rogue MCAS is a risk and a factor beyond what a 2 pilot crew should be required to handle. By the time you identify it, shut it off, and crank the trim back you’re probably in bad shape anyway.

Second issue is calling technology a crutch when ironically the 737’s lack of technological advancement causes this problem.

I think the issue is that actually pilots are well versed in dealing with certain cases of runaway trim, e.g. autopilot failures and STS, but not some of the corner cases. This means that the actual practice often stops short of going through the whole checklist. This will have been compounded by the point in the flight, low, and the presence of other potentially confusing information, .e.g stick shaker, IAS Disagree, etc.

danirich26 wrote:

Jamie514 wrote:

Bradin wrote:

Could any A320 pilots inform us whether the Flight Envelope Protection would push the nose down upon detecting a stall?

Equally important would be whether Airbus FBW would ever correct a percieved stall based on a single set of sensor data.

My understanding is they rely on input from three AoA sensors as a failsafe.

Bradin wrote:

a380900 wrote:

The A320 does not need an MCAS. It has fly by wire too.

Could any A320 pilots inform us whether the Flight Envelope Protection would push the nose down upon detecting a stall?

In short, yes, it would. The protection you are referencing is the angle of attack protection.

To give a simple explanation of the system, at the bottom of the speed tape is an amber line followed by amber/black tape, followed by red and black tape. It starts from the top of the amber line, this is called αVLS (the minimum allowed speed for this weight/config etc...) if you continue to fall below αVLS, then you will enter the amber/black tape section, this section is known as VαPROT. Once you enter this section, the THS is frozen in position and "ALPHA FLOOR" protection will be automatically engaged by the aircraft, this is basically TOGA thrust setting regardless of how you've set the thrust. Once you drop all the way down the amber and black speed tape, you will hit what is known as VαMAX (the start of the red and black tape section), this is the point at which the aeroplane will start to nose down and reduced the pitch authority of the pilot, the aeroplane will maintain VαMAX and will stabilise at that speed, which is close to, but not less than the 1G stall speed. Should the pilot release the sidestick pressure, the aeroplane will automatically nose down to the point where it will regain VαPROT speed and will stay there, it also limits nose up trim in this configuration, with only nose down trim remaining available.

So the aeroplane will not fall from the sky unless something has gone very wrong with the computers, even in alternate law (with reduced protections) there is still low speed stability built in, where a progressive nose down is ordered by the aeroplane to stop you from falling past VLS and VSW (stall warning speed)

Hope this answered your question without being too complicated!



(A320 F/O)

Thank you for this concise but clear explanation.

osiris30 wrote:

Well; do you know the failure rate for the AoA sensors? (I don't know I am asking). The answer to that question will likely contain the answer to your question. If they have a very low failure rate, where it is reasonable to expect there to not be another incident triggered by the same thing, especially in light of the bulletin going out addressing what to do if it DOES happen, then it is perfectly safe to not ground anything.

AoA sensors are mechanic and stick out of the airplane and can freeze up, be bent, ...you get the idea.
Independent of how reliable they are "inside" the device overall is assuredly not "very low failure rate".
Interesting that Airbus and Boeing have rather differing stances towards redundancy. ( same for the batteries back when: Boeing thinks : 2 asymmetrically used badly designed ones were sufficient while Airbus used a 2 plus 2 redundant environmentally managed arrangement. )

I'm curious if anyone has some informed insight into what compensation claims airlines can make against Boeing for loss of use of the MAX aircraft they were using before the grounding.

Suppose airline A had 5 aircraft flying routes that were profitable while airline B had 5 aircraft flying routes that were unprofitable. Would airline A be able to win compensation while airline B would not?

In general, what factors would come into play. Cost of financing the purchase/lease? Cost of crew trained for the MAX who might now be doing nothing? etc etc

Any answers will be received with interest.

Just as another thought: if the FAA were found to be negligent in their certification (eg outsourced too much decision making to Boeing) would they be a target to provide compensation?

art wrote:

I'm curious if anyone has some informed insight into what compensation claims airlines can make against Boeing for loss of use of the MAX aircraft they were using before the grounding.

Well, there's two sides to this:

1) All those thousands of different companies, organizations and individual people asking for compensation based on what they deem fair, as well as the opportunistic ones who just want to get as much money out of Boeing/FAA/younameit as possible

2) Boeings ability to pay compensation before going bust.

In the end there will be claim cases probably in the hundreds of billions of USD. To which Boeing will say, fine, we can then just close the business. Which I'm sure nobody wants. So then debate goes on for some years, until the compensation amounts are at a reasonable level, something gets paid, something not, whatever it is we don't know. Maybe the US government will get involved one way or the other.

Most airlines will probably just make a deal with Boeing behind closed doors, luckily Boeing should be able to offer something else as well than just monetary instruments for compensation.

Carlos01 wrote:

In the end there will be claim cases probably in the hundreds of billions of USD. To which Boeing will say, fine, we can then just close the business.

Huge overestimation. Lease of 737 costs ~USD200K per month. I believe that is the maximum airlines with grounded planes are entitled. 350 planes. Do the math. 350 victims of the crash. 1M per.

Boeing will not close business. This whole mess is FAR from busting them. The have space and defense divisions that account for half of their revenues.

ArgentoSystems wrote:

Carlos01 wrote:

In the end there will be claim cases probably in the hundreds of billions of USD. To which Boeing will say, fine, we can then just close the business.

Huge overestimation. Lease of 737 costs ~USD200K per month. I believe that is the maximum airlines with grounded planes are entitled. 350 planes. Do the math. 350 victims of the crash. 1M per.

Boeing will not close business. This whole mess is FAR from busting them. The have space and defense divisions that account for half of their revenues.

I guess that Boeing's liability to airlines is not limited to just the finance costs of the hardware. Are they not liable to compensate airlines for personnel sitting around doing nothing? Correct me if wrong, but I imagine cabin crew trained for the MAX cannot switch to another type unless they have currently valid training for that other type.

art wrote:

I guess that Boeing's liability to airlines is not limited to just the finance costs of the hardware. Are they not liable to compensate airlines for personnel sitting around doing nothing? Correct me if wrong, but I imagine cabin crew trained for the MAX cannot switch to another type unless they have currently valid training for that other type.

Yes, maybe. Still it is not huge money. We are talking about salary for 2000 people. (350 planes x 6 pilots each.) 10K per month each. 20M per month. That's nothing. Fine, maybe add another 40M for flight-attendants. Still nothing.

art wrote:

ArgentoSystems wrote:

Carlos01 wrote:

In the end there will be claim cases probably in the hundreds of billions of USD. To which Boeing will say, fine, we can then just close the business.

Huge overestimation. Lease of 737 costs ~USD200K per month. I believe that is the maximum ai justrlines with grounded planes are entitled. 350 planes. Do the math. 350 victims of the crash. 1M per.

Boeing will not close business. This whole mess is FAR from busting them. The have space and defense divisions that account for half of their revenues.

I guess that Boeing's liability to airlines is not limited to just the finance costs of the hardware. Are they not liable to compensate airlines for personnel sitting around doing nothing? Correct me if wrong, but I imagine cabin crew trained for the MAX cannot switch to another type unless they have currently valid training for that other type.

For leased hardware Boeing has no direct responsibility to the airline. Their responsibility is to the lessor. Their insurance will cover any such claims as part of errors and omissions. I can't even imagine the size of policy they must have for that but am sure it is very sizeable.

At the end of the day if the claims are severe enough Boeing will have instruments in place to deal with it. At some points governments would step in to prevent downstream impacts on their economies if Boeing was threatened.

That said Boeing's total exposure assuming this doesn't drag on for 6+ months is likely less than Airbus's on the 380.