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-   -   Boeing 737 MAX 8 crashes and effects on AA 737 MAX 8s (NOT reaccommodation) (https://www.flyertalk.com/forum/american-airlines-aadvantage/1939333-boeing-737-max-8-crashes-effects-aa-737-max-8s-not-reaccommodation.html)

clubord Oct 31, 19 8:44 pm


Originally Posted by cmd320 (Post 31688217)
It is when the need for the response is because of a faulty system.

We have a QRH full of procedures to address faulty systems. Lots of design flaws I guess.

shimps1 Oct 31, 19 9:30 pm


Originally Posted by dblumenhoff (Post 31687928)
There is nothing to stop them from manually trimming the plane even during an MCAS activation, so the time between is not the only time they could have taken action. They had either 6 or 11 minutes to identify and solve the problem depending on where you count from. The 5 seconds is a red herring.



Yes, pilots make mistakes. That's why airplanes have checklists - they've saved countless lives. An engine failure is also potentially life-threatening, and yet they happen all the time and people are safe, because pilots use their checklists and either restart the engine or land the plane. And I'm not saying that Boeing is innocent here - had they been more transparent about this issue, pilots could have practiced this in a simulator just like they practice engine failures and they would more quickly recognize it as a very specific issue rather than running a checklist about runaway trim more generally. All I'm saying is:
1) An ATP holding pilot who passed all checkrides and who was healthy and on FAA minimum rest could have recovered
2) Once the problem was identified, pilots could recognize the issue and respond appropriately (even the flu and whatever situation) and the plane would be plenty safe given that
3) Once they make these repairs, it will likely not have any false activations anyway
4) Even if none of the above were the case, my back of the hand calculation suggests that if the MAX kept up its existing safety record up until the point of the crash, it is STILL SAFER THAN DRIVING. So if you are saying you would never fly a MAX, you shouldn't be getting in any cars either.

Engine failures don't point the plane straight down, throwing off the pilot's center of gravity, making it hard to move around the cockpit, let alone fly the plane.

The entire blame for this falls on Boeing. Incorrect training, guided by them, put two planes into the ground. Making a safety critical AoA sensor duplication an option is 100% on them. There should never be a situation where a plane turns itself into an unguided missile, forcing pilots to determine the issue and save the plane in a very short amount of time. That should ONLY happen with mechanical failures, things breaking. The Max airframe is an inherently unstable design, that Boeing forced out the door because the Neo is a more comfortable, stable, superior product. Blaming "foreign pilots" is xenophobic and that is the true red herring here.

nancypants Oct 31, 19 9:50 pm


Originally Posted by shimps1 (Post 31688391)
Engine failures don't point the plane straight down, throwing off the pilot's center of gravity, making it hard to move around the cockpit, let alone fly the plane.

The entire blame for this falls on Boeing. Incorrect training, guided by them, put two planes into the ground. Making a safety critical AoA sensor duplication an option is 100% on them. There should never be a situation where a plane turns itself into an unguided missile, forcing pilots to determine the issue and save the plane in a very short amount of time. That should ONLY happen with mechanical failures, things breaking. The Max airframe is an inherently unstable design, that Boeing forced out the door because the Neo is a more comfortable, stable, superior product. Blaming "foreign pilots" is xenophobic and that is the true red herring here.

with respect, the people qualified to make this judgement, namely the NTSC, have deemed (after exhaustive examination of all of the evidence) that the entire blame did NOT fall on Boeing, not even close.

there is a reason that professionals are employed to make these kind of judgements. Please give them the dignity of having some vague degree of respect for their work

dblumenhoff Oct 31, 19 10:49 pm


Originally Posted by shimps1 (Post 31688391)
That should ONLY happen with mechanical failures, things breaking.

Things (namely, the AoA sensor) broke. It broke before the previous flight and mechanics hid the records that they didn't fix anything.


Blaming "foreign pilots" is xenophobic.
I agree. That's why I didn't do it. I see where you might have thought that. I had no assumptions about the pilots before this report came out. Let's re-read what I wrote:

An ATP holding pilot who passed all checkrides and who was healthy and on FAA minimum rest

These were specific responses to the pilots in this case, one of whom had the flu and was called in to work and the other who had multiple failed checkrides. It's a straw man argument.

cmd320 Nov 1, 19 9:51 am


Originally Posted by dblumenhoff (Post 31688520)
Things (namely, the AoA sensor) broke. It broke before the previous flight and mechanics hid the records that they didn't fix anything.

Why was the system ever designed without redundancy in the first place?

JDiver Nov 1, 19 2:07 pm


Originally Posted by cmd320 (Post 31689922)
Why was the system ever designed without redundancy in the first place?

Redundancy was made an optional extra, available separately or together at an additional price. Ultimate greed, IMO.

1) (both) Angle of Attack sensor display in Primary flight display

2) Angle of Attack disagree warning (does not operate unless #1 is installed)

Ethiopian, Lion, United purchased neither. Iirc they saved ~$55,000 per aircraft.

Southwest purchased (2), but weren’t told by Boeing it wouldn’t work without (1).

American, to give credit where it’s due, purchased both for their MAX aircraft.

24left Nov 1, 19 6:07 pm

https://cimg5.ibsrv.net/gimg/www.fly...eb0fa14820.png


QUOTE:

ďThe 28,000 flight attendants working for American Airlines refuse to walk onto a plane that may not be safe and are calling for the highest possible safety standards to avoid another tragedy,Ē Association of Professional Flight Attendants President Lori Bassani said in the letter."


Full article https://www.reuters.com/article/us-b...-idUSKBN1XA2JO


Mods - didn't see this posted. Feel free to move/merge. Thanks.

ryan182 Nov 1, 19 10:24 pm


Originally Posted by JDiver (Post 31690965)
Redundancy was made an optional extra, available separately or together at an additional price. Ultimate greed, IMO.

1) (both) Angle of Attack sensor display in Primary flight display

2) Angle of Attack disagree warning (does not operate unless #1 is installed)

Ethiopian, Lion, United purchased neither. Iirc they saved ~$55,000 per aircraft.

Southwest purchased (2), but werenít told by Boeing it wouldnít work without (1).

American, to give credit where itís due, purchased both for their MAX aircraft.

$55,000 an aircraft...that's what I find to be the worst part of this debacle given the loss of life. Clearly Boeing should have never allowed these features optional, and while my initial reaction reading that was to cast some blame on the airlines for trying to save a few pennies - which realistically $55K is couch money when you're buying an 737, but it doesn't seem like Boeing was transparent about the implications of not having these redundancies which brings me back to why were they optional in the first place?!

No one was going to cancel a 737MAX order in favor of a different plane over $55K, when you amortize that over the life of the plane its not even a rounding error. ^ to AA for buying both options, but that also makes me curious was it a case of we want all the options loader up or did AA have some data that showed that not having these options could result in a catastrophic failure? And did Southwest, who bought (2) and was told it wouldn't work without (1) still just buy (2) - cause that just sounds wonky as why buy something you're told won't work?

steve64 Nov 2, 19 4:04 pm


Originally Posted by JDiver (Post 31690965)
Redundancy was made an optional extra, available separately or together at an additional price. Ultimate greed, IMO.

1) (both) Angle of Attack sensor display in Primary flight display

2) Angle of Attack disagree warning (does not operate unless #1 is installed)

Ethiopian, Lion, United purchased neither. Iirc they saved ~$55,000 per aircraft.

Southwest purchased (2), but werenít told by Boeing it wouldnít work without (1).

American, to give credit where itís due, purchased both for their MAX aircraft.

I believe you're getting 2 similar concepts confused.

The 2 options you mention are for providing AoA info directly to the pilots.
On the other hand, a major flaw (IMHO) of MCAS is that it acted on data only from one of the 2 AoA sensors on the aircraft. I'd imagine the auto-pilot reads from both sensors. MCAS continuously "adjusting" trim for an erroneous readings from a single sensor, with no comparison to the other sensor (and no attempt to validate the data from the sensor it was reading), is the lack of redundancy I think the other poster was referring to. MCAS should have redundant readings irrelevant of the options purchased for pilot indications.

For either of the options to have helped avoid the crashes, the pilots would've needed full training on MCAS including the fact that if the single AoA is giving faulty readings, then MCAS will activate (trim nose down repeatedly) even though it is not needed.
I don't think the optional AoA indicators are common equipment. I've never piloted a plane that had one (granted, I don't fly commercial airliners, but have friends who do). All planes have stall warning systems to indicate you're approaching an aerodynamic stall (your AoA is too high).

JDiver Nov 2, 19 7:02 pm


Originally Posted by steve64 (Post 31694445)
I believe you're getting 2 similar concepts confused.

The 2 options you mention are for providing AoA info directly to the pilots.
On the other hand, a major flaw (IMHO) of MCAS is that it acted on data only from one of the 2 AoA sensors on the aircraft. I'd imagine the auto-pilot reads from both sensors. MCAS continuously "adjusting" trim for an erroneous readings from a single sensor, with no comparison to the other sensor (and no attempt to validate the data from the sensor it was reading), is the lack of redundancy I think the other poster was referring to. MCAS should have redundant readings irrelevant of the options purchased for pilot indications.

For either of the options to have helped avoid the crashes, the pilots would've needed full training on MCAS including the fact that if the single AoA is giving faulty readings, then MCAS will activate (trim nose down repeatedly) even though it is not needed.
I don't think the optional AoA indicators are common equipment. I've never piloted a plane that had one (granted, I don't fly commercial airliners, but have friends who do). All planes have stall warning systems to indicate you're approaching an aerodynamic stall (your AoA is too high).

Iím not confused at all. :) Artificial horizon is whatís normally used, but Boeing offered AoA indication as an optional extra - and only one of the two AoA sensors is used by MCAS. The AoA indicators in the pri-fly was offered, perhaps because MCAS wasnít programmed with a data component to compare both data streams. And the AoA disagree warning was as well.

MCAS wasnít designed to receive and compare both AoA data streams, it seems. And itís pretty certain on Lion Air the data that was used by MCAS were faulty because the actual indicator was faulty; it had been reported twice, anyway, and apparently wasnít rectified or properly calibrated. (Not to mention Xtra Aerospace, LLC, of Miramar, FL, the Florida shop that sold it was shut down by the FAA for violations 25 Oct.)


MCAS was designed to rely on a single AOA sensor, making it vulnerable to erroneous input from that sensor. - Aviation Herald

nk15 Nov 2, 19 10:16 pm

If the US was a true democracy, all these Boeing criminals would have been criminally charged and prosecuted, but because it is a corporate democracy, nobody has even lost their jobs....

ryan182 Nov 2, 19 10:47 pm


Originally Posted by nk15 (Post 31695307)
If the US was a true democracy, all these Boeing criminals would have been criminally charged and prosecuted, but because it is a corporate democracy, nobody has even lost their jobs....

Actually someone did lose their job recently, President and CEO of commercial aircraft Kevin McAllister was fired in October. Further as it seems you have access to the Internet you might want to leverage that access to educate yourself, starting with the fact that the US is currently, and has always been, a representative democracy and that "true democracy" tends to end poorly. You also could have learned about the aforementioned firing from the same Internet...

steve64 Nov 2, 19 10:59 pm


Originally Posted by JDiver (Post 31694883)
Iím not confused at all. :) Artificial horizon is whatís normally used, but Boeing offered AoA indication as an optional extra - and only one of the two AoA sensors is used by MCAS. The AoA indicators in the pri-fly was offered, perhaps because MCAS wasnít programmed with a data component to compare both data streams. And the AoA disagree warning was as well.

MCAS wasnít designed to receive and compare both AoA data streams, it seems. And itís pretty certain on Lion Air the data that was used by MCAS were faulty because the actual indicator was faulty; it had been reported twice, anyway, and apparently wasnít rectified or properly calibrated. (Not to mention Xtra Aerospace, LLC, of Miramar, FL, the Florida shop that sold it was shut down by the FAA for violations 25 Oct.)

On all of the above, we're in total agreement.
MCAS did not have the redundancy of reading/comparing data from both AoA sensors.

But your original post stated "Redundancy was made an optional extra..." and went on to describe the 2 pilot display options. This suggests that buying these options would've provided redundancy and avoided the crashes.
However :
  • the plane has 2 AoA sensors (options purchased or not)
  • MCAS only reads from one of these sensors (options purchased or not). Only reading from one indicator, despite 2 being onboard, is a major factor in these crashes.

Option #1 - AoA indication to the pilots
AoA really only means something to the pilot if the angle is too high, they would be approaching an aerodynamic stall ... the airflow over the wings is disrupted to the point of a serious loss of lift.
Basic Airmanship : pilots should be able to note they're approaching a stall situation based on pitch (determined by the Attitude Indicator you mentioned), airspeed, control effectiveness and the stall warning.
Aircraft don't typically have an AoA indicator. The pilot should know aerodynamics and have the stall warning as a backup.

Option #2 - AoA Disagree Warning (the 2 AoA sensors disagree with each other beyond some prescribed/acceptable variance).
I assume the AoA sensors are on the plane to support the stall warning system (and possibly the autopilot).
Despite the faulty AoA issuing a false "nose too high" indication, the stall warning did not activate on either crash (nor the Lion Air crash on the same plane on its previous flight).
Therefore: I assume the stall warning system had some redundancy programmed in. The "other" AoA sensor did not sense "nose high" and based on pitch & airspeed, the "other" AoA's data seemed more logical than the "nose high" data. No stall warning issued.
MCAS read the faulty AoA sensor, thought the nose was too high, thus issued continuous nose down trim inputs.
An "AoA Disagree" light would've only helped if the pilots knew all of the below :
  • what an "MCAS" was
  • MCAS only reads from a single AoA sensor
  • if the 2 AoA sensors disagree, and if the sensor read by MCAS is the incorrect reading, and if that false reading is "too high" then MCAS is going to go crazy
The Lion Air pilots had no knowledge of any of those bullet points.
The Ethiopian pilots should've had knowledge of MCAS, but to what extent I have no idea. It's possible that with an AoA Disagree light they may have recognized that their "control problems" were "that MCAS thing" a little sooner and deactivated the trim switches earlier.
The Indonesian report of the Lion Air crash is out. It lists many factors as contributing to the crash. In my quick scan, it does not list the lack of purchasing the AoA options as a factor.
Your post has lead at least one FTer (ryan182) to believe that the lack of this $55,000 option(s) is what brought the planes down. Not true.

I hope I'm not sounding as if I'm arguing with you. You're one of my favorite and most respected posters here. This is just "casual debate" :cool:
I think we're way more in agreement, with the problem word being "redundancy". Yea, buying the option(s) provides redundancy; but the planes crashed because MCAS lacks the redundancy of reading/comparing/validating data from both AoA sensors.
Oh ... your post that I originally replied to have been moved to the "other thread", but followups to it haven't

ryan182 Nov 2, 19 11:46 pm


Originally Posted by steve64 (Post 31695372)
Your post has lead at least one FTer (ryan182) to believe that the lack of this $55,000 option(s) is what brought the planes down. Not true.

Just to clarify, I was not implying that absent all other factors the lack of a $55,000 option(s) brought down the planes. As has been the case with just about every loss of life event since the advent of commercial aviation there's a series of events that ultimately result in catastrophic failure. Its possible that even with said options these events would have still happened, we don't/can't know, but that doesn't change my view that these shouldn't have been optional .

moondog Nov 3, 19 7:07 am


Originally Posted by ryan182 (Post 31695356)
Actually someone did lose their job recently, President and CEO of commercial aircraft Kevin McAllister was fired in October. Further as it seems you have access to the Internet you might want to leverage that access to educate yourself, starting with the fact that the US is currently, and has always been, a representative democracy and that "true democracy" tends to end poorly. You also could have learned about the aforementioned firing from the same Internet...

Mullienberg(sp?) should have resigned, as well; during his congressional testimony, he admitted that he didn't receive the alarms from the frontline guys; this is completely understandable, and happens in companies of all sizes, BUT I hold aircraft manufactures to higher standards


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