smartplane
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Re: B737MAX Grounded Worldwide

Thu Apr 25, 2019 8:29 pm

morrisond wrote:
What instability does the MAX approach at High AOA? The controls just get a little light - that does not make it unstable.

Before coming up with the MCAS name, Boeing referred to it as Pitch Stability Augmentation. This should point us in the right direction.
 
kalvado
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Re: B737MAX Grounded Worldwide

Thu Apr 25, 2019 8:40 pm

hivue wrote:
kalvado wrote:
As I sad earlier:
kalvado wrote:
If MCAS is indeed fixed to behave, then pilots may safely ignore its existence as the only case where MCAS would encounter is when it is helping pilot, and pilot doesn't even have to know that.


I'm getting a feeling of deja vu all over again. This almost certainly is the logic Boeing engineers used for OK-ing MCAS 1.0.

Because they had a point, you know. Problem of MCAS was that it functioned in a crazy manner, if it behaved- nobody would know what it is by now. But MCAS went nuts, and unprepared crew didn't get much chance. Even prepared (whatever Boeing tries to push through right now) failed.
I am not saying "hide it". I am saying proper assistance system - if you drive, think about anti-lock brakes, stability assistance and what not is there today - helps when you really don't know much about it.
PROPER is the keyword.
 
morrisond
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Re: B737MAX Grounded Worldwide

Thu Apr 25, 2019 9:00 pm

smartplane wrote:
morrisond wrote:
What instability does the MAX approach at High AOA? The controls just get a little light - that does not make it unstable.

Before coming up with the MCAS name, Boeing referred to it as Pitch Stability Augmentation. This should point us in the right direction.


So then please point us in the right direction and provide a Pilot report or an FAA test report that the MAX is unstable and will fall out of the sky unless you are an ace pilot or stop insinuating things you can't support.
 
morrisond
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Re: B737MAX Grounded Worldwide

Thu Apr 25, 2019 9:01 pm

kalvado wrote:
hivue wrote:
kalvado wrote:
As I sad earlier:


I'm getting a feeling of deja vu all over again. This almost certainly is the logic Boeing engineers used for OK-ing MCAS 1.0.

Because they had a point, you know. Problem of MCAS was that it functioned in a crazy manner, if it behaved- nobody would know what it is by now. But MCAS went nuts, and unprepared crew didn't get much chance. Even prepared (whatever Boeing tries to push through right now) failed.
I am not saying "hide it". I am saying proper assistance system - if you drive, think about anti-lock brakes, stability assistance and what not is there today - helps when you really don't know much about it.
PROPER is the keyword.


That was MCAS V1.

So what do you think is wrong with MCAS V2 then?
 
kalvado
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Re: B737MAX Grounded Worldwide

Thu Apr 25, 2019 9:22 pm

morrisond wrote:
kalvado wrote:
hivue wrote:

I'm getting a feeling of deja vu all over again. This almost certainly is the logic Boeing engineers used for OK-ing MCAS 1.0.

Because they had a point, you know. Problem of MCAS was that it functioned in a crazy manner, if it behaved- nobody would know what it is by now. But MCAS went nuts, and unprepared crew didn't get much chance. Even prepared (whatever Boeing tries to push through right now) failed.
I am not saying "hide it". I am saying proper assistance system - if you drive, think about anti-lock brakes, stability assistance and what not is there today - helps when you really don't know much about it.
PROPER is the keyword.


That was MCAS V1.

So what do you think is wrong with MCAS V2 then?

Because I'm afraid that MCAS is thirteenth strike of the clock - and now that one is worked out, but other twelve still need to be looked at.
I don't think MCAS specific training is on order once that issue is fixed, but that doesn't mean the rest of the plane is in a good shape. It may be, but maybe not. EASA and CAAC should inform Boeing and FAA about conclusions of their analysis.
 
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PW100
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Re: B737MAX Grounded Worldwide

Thu Apr 25, 2019 9:42 pm

morrisond wrote:
They were above Vmo for most of the time - that is not within the normal flight envelope.

Even at the time when they were slightly below Vmo they were 100 knots over the normal climb speed (which they tried to set at 238 Knots on the Autopilot).

In any case in normal operation they would never get near Vmo (340 knots) - Climb is about 240 as above, cruise about 240 knots Indicated at altitude (above 35,000')- they would only go higher in a wings level descent and probably not get anywhere near Vmo. Reading Various Pilot forums on 737 descent seems to be 250 KIAS normal - up to about 280KIAS

At 10,000' above Sea Level - you need to be below 250 KIAS.


Not being a pilot, but it was mentioned earlier in this thread that with unreliable airspeed and/or stickshaker normal air speeds are no longer applicable. Is that correct? What would be a normal airspeed range in said conditions?
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PW100
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Re: B737MAX Grounded Worldwide

Thu Apr 25, 2019 9:46 pm

zeke wrote:
Amiga500 wrote:
It is quite clearly deficient with regards 25.671


It is difficult to have a sensible discussion when you read comments like this. That FAR is not appropriate to this situation, the control surfaces were not jammed.

I would like to think if you put 10 random 737 crews in a simulator and told them just after liftoff you are going to have a AOA failure, stick shaker will come on immediately. We want you to come back and land. I think all of the crews would have no problem getting the aircraft on the ground safely. It does not take any extra
ordinary skill or strength.

What I do not understand is the mindset of three crews to basically think they can ignore a stick shaker and continue onto their destination. The JT and ET crashes both basically happened early morning in day VMC.


FWIW, as far as we know, the crew that continued with stick shaker to destination is the only crew that successfully managed rogue AoA and MCAS going crazy. And lived to tell . . .
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PW100
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Re: B737MAX Grounded Worldwide

Thu Apr 25, 2019 9:48 pm

scbriml wrote:
bob75013 wrote:
As a point of reference Southwest alone had over 41,000 MAX flights before the plane was grounded. I suspect that is more than any other single airline


How many AOA failures on those flights just at take-off?


I guess you are not surprised to not see an answer on your post.
At least, no one came out suggesting it was the super Southwest maintenance that kept AoA failures within acceptable rates . . .
Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
 
jollo
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Re: B737MAX Grounded Worldwide

Thu Apr 25, 2019 10:17 pm

kalvado wrote:
hivue wrote:
kalvado wrote:
As I sad earlier:


I'm getting a feeling of deja vu all over again. This almost certainly is the logic Boeing engineers used for OK-ing MCAS 1.0.

Because they had a point, you know. Problem of MCAS was that it functioned in a crazy manner, if it behaved- nobody would know what it is by now. But MCAS went nuts, and unprepared crew didn't get much chance. Even prepared (whatever Boeing tries to push through right now) failed.
I am not saying "hide it". I am saying proper assistance system - if you drive, think about anti-lock brakes, stability assistance and what not is there today - helps when you really don't know much about it.
PROPER is the keyword.


PROPER implementation, for any automation with potentially hazardous failure modes, is to disable itself at once if inputs are detected to be unreliable. Following your anti-lock brakes analogy, ABS controllers spend a considerable amount of resources sanitizing input signals (there are 4 input channels, but each wheel-lock sensor has no redundancy): as soon as an unreliable input condition is detected, a yellow indicator lights up on the dashboard, the driver knows she/he is back to fully manual (servo-assisted) braking and the controller simply takes itself off the control loop.

MCAS (any version) operating on correct inputs is "invisible" to the pilot, so no training is needed. An inoperative MCAS v2 (because inputs are detected as incorrect, e.g. AoA disagree) would likely be no big deal for the pilot, just like an inoperative ABS is no big deal for a driver: you just have to know how to handle the vehicle without the control augmentation. For a driver, this means slow down on wet roads; for a pilot, this means a couple of new memory items (e.g. AoA limit at slow speed, bank angle limit at high speed, etc.).

THIS requires training.
 
OldAeroGuy
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Re: B737MAX Grounded Worldwide

Thu Apr 25, 2019 10:28 pm

PW100 wrote:
morrisond wrote:
They were above Vmo for most of the time - that is not within the normal flight envelope.

Even at the time when they were slightly below Vmo they were 100 knots over the normal climb speed (which they tried to set at 238 Knots on the Autopilot).

In any case in normal operation they would never get near Vmo (340 knots) - Climb is about 240 as above, cruise about 240 knots Indicated at altitude (above 35,000')- they would only go higher in a wings level descent and probably not get anywhere near Vmo. Reading Various Pilot forums on 737 descent seems to be 250 KIAS normal - up to about 280KIAS

At 10,000' above Sea Level - you need to be below 250 KIAS.


Not being a pilot, but it was mentioned earlier in this thread that with unreliable airspeed and/or stickshaker normal air speeds are no longer applicable. Is that correct? What would be a normal airspeed range in said conditions?


Only on one side, in the ET302 case, the Left. The Right side airspeed was working fine and it got up to 360+kts KIAS, at least 20 kts above the placard.

A normal climb profile would have been 280 kts until hitting around 0.78M and then climb/cruise at about 0.78M.

The dynamic pressure at 360 kts is about 65% higher than at 280 kts. In Ethiopian, I'm not sure the 250 kt speed limit applies. It's a US rule.
Last edited by OldAeroGuy on Thu Apr 25, 2019 10:36 pm, edited 1 time in total.
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NeBaNi
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Re: B737MAX Grounded Worldwide

Thu Apr 25, 2019 10:32 pm

morrisond wrote:
They were above Vmo for most of the time - that is not within the normal flight envelope.

Even at the time when they were slightly below Vmo they were 100 knots over the normal climb speed (which they tried to set at 238 Knots on the Autopilot).

In any case in normal operation they would never get near Vmo (340 knots) - Climb is about 240 as above, cruise about 240 knots Indicated at altitude (above 35,000')- they would only go higher in a wings level descent and probably not get anywhere near Vmo. Reading Various Pilot forums on 737 descent seems to be 250 KIAS normal - up to about 280KIAS

At 10,000' above Sea Level - you need to be below 250 KIAS.

Sure, and I'm saying that because they were not within the normal flight envelope (as you've also been saying, not arguing there), the aircraft fails to meet certification. To me, the part that I quoted implies that despite flight/ control system failures, the aircraft must be within normal flight envelope without requiring exceptional pilot skill or strength. The fact that it wasn't within the normal flight envelope suggests that it shouldn't have been certified as such.
 
kalvado
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Re: B737MAX Grounded Worldwide

Thu Apr 25, 2019 10:35 pm

jollo wrote:
kalvado wrote:
hivue wrote:

I'm getting a feeling of deja vu all over again. This almost certainly is the logic Boeing engineers used for OK-ing MCAS 1.0.

Because they had a point, you know. Problem of MCAS was that it functioned in a crazy manner, if it behaved- nobody would know what it is by now. But MCAS went nuts, and unprepared crew didn't get much chance. Even prepared (whatever Boeing tries to push through right now) failed.
I am not saying "hide it". I am saying proper assistance system - if you drive, think about anti-lock brakes, stability assistance and what not is there today - helps when you really don't know much about it.
PROPER is the keyword.


PROPER implementation, for any automation with potentially hazardous failure modes, is to disable itself at once if inputs are detected to be unreliable. Following your anti-lock brakes analogy, ABS controllers spend a considerable amount of resources sanitizing input signals (there are 4 input channels, but each wheel-lock sensor has no redundancy): as soon as an unreliable input condition is detected, a yellow indicator lights up on the dashboard, the driver knows she/he is back to fully manual (servo-assisted) braking and the controller simply takes itself off the control loop.

MCAS (any version) operating on correct inputs is "invisible" to the pilot, so no training is needed. An inoperative MCAS v2 (because inputs are detected as incorrect, e.g. AoA disagree) would likely be no big deal for the pilot, just like an inoperative ABS is no big deal for a driver: you just have to know how to handle the vehicle without the control augmentation. For a driver, this means slow down on wet roads; for a pilot, this means a couple of new memory items (e.g. AoA limit at slow speed, bank angle limit at high speed, etc.).

THIS requires training.

Of course. A bigger question is if we are talking about the training as 3 slides and a checkist, or training as an annual sim session? So far, sim session seems to be the answer,van excessive one IMHO
 
multimark
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Re: B737MAX Grounded Worldwide

Thu Apr 25, 2019 10:36 pm

Air Canada has rejigged schedules and now plan for the 738 Max being out of service through July 31.
https://www.theglobeandmail.com/busines ... boeing-73/
 
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SheikhDjibouti
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 12:10 am

PW100 wrote:
morrisond wrote:
They were above Vmo for most of the time - that is not within the normal flight envelope.

Even at the time when they were slightly below Vmo they were 100 knots over the normal climb speed (which they tried to set at 238 Knots on the Autopilot).

In any case in normal operation they would never get near Vmo (340 knots) - Climb is about 240 as above, cruise about 240 knots Indicated at altitude (above 35,000')- they would only go higher in a wings level descent and probably not get anywhere near Vmo. Reading Various Pilot forums on 737 descent seems to be 250 KIAS normal - up to about 280KIAS

At 10,000' above Sea Level - you need to be below 250 KIAS.


Not being a pilot, but it was mentioned earlier in this thread that with unreliable airspeed and/or stickshaker normal air speeds are no longer applicable. Is that correct? What would be a normal airspeed range in said conditions?
"Climb at 240, cruise at 240" :o
If only there was a feature somewhere on the internet, where we could watch 737s in real time on radar, maybe 24 hrs a day, in order to glean some data regarding typical climb-outs. :scratchchin:
The problem us peasants have is that without premium (paid) membership, we can only view groundspeed data, not IAS.

The first problem with that is wind direction, and variability at altitude, but if you pick a busy hub in a central location with lots of 737-800s departing, you can follow different flights heading North, South, East & West, and average out the results.
This still doesn't give you IAS, but here is what I found.

Boeing 737-800 aircraft will often reach 270kts groundspeed whilst climbing through 7,000ft
Between 10 and 12,000 ft, groundspeeds of 310 to 380 kts can be seen, with a strong suspicion the a/c at 380kts had the benefit of a tailwind.
However, by around FL200, 380kts is quite common in all directions.
And finally, a/c climbing through FL330 whilst on their way to even higher altitudes, would typically show 430-460kts groundspeed.

Somebody else will have to explain the intricacies of why groundspeed and IAS are different. I would have a go myself, but I'm under enough pressure as it is.... :spin:

And if you are really lucky, somebody might even have FR24 premium membership and share some of their data with us.....

I also have observations regarding the often quoted 250 KIAS number, but you can read them in my next post to OAG.
Nothing to see here; move along please.
 
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SheikhDjibouti
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 12:14 am

OldAeroGuy wrote:
morrisond wrote:
They were above Vmo for most of the time - that is not within the normal flight envelope.

In any case in normal operation they would never get near Vmo (340 knots) - Climb is about 240 as above, cruise about 240 knots Indicated at altitude (above 35,000')- they would only go higher in a wings level descent and probably not get anywhere near Vmo.

At 10,000' above Sea Level - you need to be below 250 KIAS.

A normal climb profile would have been 280 kts until hitting around 0.78M and then climb/cruise at about 0.78M.

The dynamic pressure at 360 kts is about 65% higher than at 280 kts.

In Ethiopian, I'm not sure the 250 kt speed limit applies. It's a US rule.

Yes, and no.(the last bit)
There are two solid reasons for imposing 250kt limits below 10,000ft; bird strike risk and traffic avoidance.
14 CFR 25.571 specifically mentions " Impact with a 4-pound bird when the velocity of the airplane relative to the bird along the airplane's flight path is equal to Vc at sea level or 0.85Vc at 8,000 feet". This speed will be set per individual aircraft type.

The general 250kt speed limit is controlled by regulation and has nothing to do with aircraft controllability.

Most texts state the US and Canada enforce this limit universally, except I have this picture in my head of USN F-18s heading down Rainbow Canyon with the 'burners on. I don't know what class of airspace that counts as....

Europe, Africa and Asia typically enforce the same 250kt limit for all class D,E,F and G airspace.
AFAIK if you are IFR and in class B or C airspace, usually there is no formal speed limit, however as this is controlled airspace it will be at ATC discretion.
If you need to know what each class of airspace is, I'll let somebody else answer that one. Or there is the internet....

Note; with ADD Addis Ababa at 7,600ft elevation, ET302 were fairly quickly above 10,000ft and hence 250 KIAS is even more of a red herring.
Nothing to see here; move along please.
 
morrisond
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 12:20 am

PW100 wrote:
morrisond wrote:
They were above Vmo for most of the time - that is not within the normal flight envelope.

Even at the time when they were slightly below Vmo they were 100 knots over the normal climb speed (which they tried to set at 238 Knots on the Autopilot).

In any case in normal operation they would never get near Vmo (340 knots) - Climb is about 240 as above, cruise about 240 knots Indicated at altitude (above 35,000')- they would only go higher in a wings level descent and probably not get anywhere near Vmo. Reading Various Pilot forums on 737 descent seems to be 250 KIAS normal - up to about 280KIAS

At 10,000' above Sea Level - you need to be below 250 KIAS.


Not being a pilot, but it was mentioned earlier in this thread that with unreliable airspeed and/or stickshaker normal air speeds are no longer applicable. Is that correct? What would be a normal airspeed range in said conditions?


They had backup airspeed on a separate Instrument on a separate source that they should have cross checked (totally normal expected procedure) with the Co-pilots Instruments. This would have confirmed the correct airspeed on the co-pilots intstuments and normal airspeeds could have been flown by the Co-pilot. You might want to add a little extra on approach just in case - but in flight at say 200-240 knots almost zero risk of stalling if you watch your AOA which was still working on the co-pilots side as well.

They train all the time for this. However I would understand the Co-pilots reluctance to hand it over to an Co-pilot with only 250 hours - but that is a topic for another discussion.
 
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zeke
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 12:34 am

SheikhDjibouti wrote:
Yes, and no.(the last bit)
There are two solid reasons for imposing 250kt limits below 10,000ft; bird strike risk and traffic avoidance.
14 CFR 25.571 specifically mentions " Impact with a 4-pound bird when the velocity of the airplane relative to the bird along the airplane's flight path is equal to Vc at sea level or 0.85Vc at 8,000 feet". This speed will be set per individual aircraft type.

The general 250kt speed limit is controlled by regulation and has nothing to do with aircraft controllability.

Most texts state the US and Canada enforce this limit universally, except I have this picture in my head of USN F-18s heading down Rainbow Canyon with the 'burners on. I don't know what class of airspace that counts as....

Europe, Africa and Asia typically enforce the same 250kt limit for all class D,E,F and G airspace.
AFAIK if you are IFR and in class B or C airspace, usually there is no formal speed limit, however as this is controlled airspace it will be at ATC discretion.
If you need to know what each class of airspace is, I'll let somebody else answer that one. Or there is the internet....

Note; with ADD Addis Ababa at 7,600ft elevation, ET302 were fairly quickly above 10,000ft and hence 250 KIAS is even more of a red herring.



And yet I often do 300 - 335 kts IAS below 10......
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OldAeroGuy
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 12:41 am

kalvado wrote:

Because I'm afraid that MCAS is thirteenth strike of the clock - and now that one is worked out, but other twelve still need to be looked at.
I don't think MCAS specific training is on order once that issue is fixed, but that doesn't mean the rest of the plane is in a good shape. It may be, but maybe not. EASA and CAAC should inform Boeing and FAA about conclusions of their analysis.


Well, you've lost me with this one.

No real reason to complain after MCAS.v2 is approved, but you just don't like the airplane.

Very well, there is no way to use rational discussion against faith or superstition.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
morrisond
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 12:44 am

jollo wrote:
kalvado wrote:
hivue wrote:

I'm getting a feeling of deja vu all over again. This almost certainly is the logic Boeing engineers used for OK-ing MCAS 1.0.

Because they had a point, you know. Problem of MCAS was that it functioned in a crazy manner, if it behaved- nobody would know what it is by now. But MCAS went nuts, and unprepared crew didn't get much chance. Even prepared (whatever Boeing tries to push through right now) failed.
I am not saying "hide it". I am saying proper assistance system - if you drive, think about anti-lock brakes, stability assistance and what not is there today - helps when you really don't know much about it.
PROPER is the keyword.


PROPER implementation, for any automation with potentially hazardous failure modes, is to disable itself at once if inputs are detected to be unreliable. Following your anti-lock brakes analogy, ABS controllers spend a considerable amount of resources sanitizing input signals (there are 4 input channels, but each wheel-lock sensor has no redundancy): as soon as an unreliable input condition is detected, a yellow indicator lights up on the dashboard, the driver knows she/he is back to fully manual (servo-assisted) braking and the controller simply takes itself off the control loop.

MCAS (any version) operating on correct inputs is "invisible" to the pilot, so no training is needed. An inoperative MCAS v2 (because inputs are detected as incorrect, e.g. AoA disagree) would likely be no big deal for the pilot, just like an inoperative ABS is no big deal for a driver: you just have to know how to handle the vehicle without the control augmentation. For a driver, this means slow down on wet roads; for a pilot, this means a couple of new memory items (e.g. AoA limit at slow speed, bank angle limit at high speed, etc.).

THIS requires training.


Those speeds would be basic knowledge for anyone who is in the cockpit of any 737. They would not be new memory items as MCAS was never designed as a stall prevention system and you would need to know these anyways in case any of the Nannies failed. They are not something you would be allowed to look up. You have to be able to fly the aircraft on the backup instrument alone to get type rated (I'm assuming but this shouldn't be a big assumption - and if it isn't a requirement WTF!)

I believe the symbology on the instruments provides this data as well.
 
morrisond
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 12:50 am

NeBaNi wrote:
morrisond wrote:
They were above Vmo for most of the time - that is not within the normal flight envelope.

Even at the time when they were slightly below Vmo they were 100 knots over the normal climb speed (which they tried to set at 238 Knots on the Autopilot).

In any case in normal operation they would never get near Vmo (340 knots) - Climb is about 240 as above, cruise about 240 knots Indicated at altitude (above 35,000')- they would only go higher in a wings level descent and probably not get anywhere near Vmo. Reading Various Pilot forums on 737 descent seems to be 250 KIAS normal - up to about 280KIAS

At 10,000' above Sea Level - you need to be below 250 KIAS.

Sure, and I'm saying that because they were not within the normal flight envelope (as you've also been saying, not arguing there), the aircraft fails to meet certification. To me, the part that I quoted implies that despite flight/ control system failures, the aircraft must be within normal flight envelope without requiring exceptional pilot skill or strength. The fact that it wasn't within the normal flight envelope suggests that it shouldn't have been certified as such.


Sorry - I'm not understanding what you are trying to say. What shouldn't have been certified?
 
9Patch
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 12:52 am

jollo wrote:
MCAS (any version) operating on correct inputs is "invisible" to the pilot, so no training is needed. An inoperative MCAS v2 (because inputs are detected as incorrect, e.g. AoA disagree) would likely be no big deal for the pilot, just like an inoperative ABS is no big deal for a driver: you just have to know how to handle the vehicle without the control augmentation. For a driver, this means slow down on wet roads; for a pilot, this means a couple of new memory items (e.g. AoA limit at slow speed, bank angle limit at high speed, etc.).

THIS requires training.

But does it require simulator training?
 
OldAeroGuy
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 1:01 am

SheikhDjibouti wrote:
Somebody else will have to explain the intricacies of why groundspeed and IAS are different. I would have a go myself, but I'm under enough pressure as it is.... :spin:


Because ground speed is more indicative of KTAS (knots, true air speed) and KIAS (knots, indicated air speed) is what the airspeed indicator will be reading.

At FL 330, Mach may be around 0.78 and KTAS (or ground speed with no wind aloft) would be 452 kts.

At the same time KIAS would be reading about 262 kts. (I was too lazy to apply the compressibility correction.

So:
Mach 0.78
KTAS 452 (ground speed)
KIAS 262 (approximately)
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
morrisond
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 1:09 am

SheikhDjibouti wrote:
PW100 wrote:
morrisond wrote:
They were above Vmo for most of the time - that is not within the normal flight envelope.

Even at the time when they were slightly below Vmo they were 100 knots over the normal climb speed (which they tried to set at 238 Knots on the Autopilot).

In any case in normal operation they would never get near Vmo (340 knots) - Climb is about 240 as above, cruise about 240 knots Indicated at altitude (above 35,000')- they would only go higher in a wings level descent and probably not get anywhere near Vmo. Reading Various Pilot forums on 737 descent seems to be 250 KIAS normal - up to about 280KIAS

At 10,000' above Sea Level - you need to be below 250 KIAS.


Not being a pilot, but it was mentioned earlier in this thread that with unreliable airspeed and/or stickshaker normal air speeds are no longer applicable. Is that correct? What would be a normal airspeed range in said conditions?
"Climb at 240, cruise at 240" :o
If only there was a feature somewhere on the internet, where we could watch 737s in real time on radar, maybe 24 hrs a day, in order to glean some data regarding typical climb-outs. :scratchchin:
The problem us peasants have is that without premium (paid) membership, we can only view groundspeed data, not IAS.

The first problem with that is wind direction, and variability at altitude, but if you pick a busy hub in a central location with lots of 737-800s departing, you can follow different flights heading North, South, East & West, and average out the results.
This still doesn't give you IAS, but here is what I found.

Boeing 737-800 aircraft will often reach 270kts groundspeed whilst climbing through 7,000ft
Between 10 and 12,000 ft, groundspeeds of 310 to 380 kts can be seen, with a strong suspicion the a/c at 380kts had the benefit of a tailwind.
However, by around FL200, 380kts is quite common in all directions.
And finally, a/c climbing through FL330 whilst on their way to even higher altitudes, would typically show 430-460kts groundspeed.

Somebody else will have to explain the intricacies of why groundspeed and IAS are different. I would have a go myself, but I'm under enough pressure as it is.... :spin:

And if you are really lucky, somebody might even have FR24 premium membership and share some of their data with us.....

I also have observations regarding the often quoted 250 KIAS number, but you can read them in my next post to OAG.


Hi Sheik - The easiest way to explain IAS is it is the Speed the airplane feels (Please everyone forgive me if I make mistakes I'm just trying to simplify it). Assuming no winds aloft - at 10,000' Your indicated Airspeed might be 250 KIAS - but your true Airspeed on a standard day would be about 300knots true air speed KTAS.

The airplane feels like it is going 250 knots but as the air is thinner at 10'000' the plane is actually going faster than indicated relative to the planes position on the ground.

At 41,000' 250KIAS would be 455 KTAS - however the plane would feel the same Dynamic pressure as at 10,000' at 250 KIAS. Vmo is based on KIAS - so as you might actually be going 455 KTAS at altitude - that is still below Vmo as you would only be 250KIAS.

Stall speeds are based on Indicated as that is basically the pressure the plane/wing feels.

So the data you are seeing on FR24 of 380 KTAS are probably more like 270 KIAS - well below Vmo.

Wikipedia does a lot better Job than me at explaining it https://en.wikipedia.org/wiki/Indicated_airspeed

Here is a calculator to convert KIAS to KTAS http://www.csgnetwork.com/tasinfocalc.html
 
kalvado
Posts: 1793
Joined: Wed Mar 01, 2006 4:29 am

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 1:11 am

OldAeroGuy wrote:
kalvado wrote:

Because I'm afraid that MCAS is thirteenth strike of the clock - and now that one is worked out, but other twelve still need to be looked at.
I don't think MCAS specific training is on order once that issue is fixed, but that doesn't mean the rest of the plane is in a good shape. It may be, but maybe not. EASA and CAAC should inform Boeing and FAA about conclusions of their analysis.


Well, you've lost me with this one.

No real reason to complain after MCAS.v2 is approved, but you just don't like the airplane.

Very well, there is no way to use rational discussion against faith or superstition.

Why, it is simple. A lot of things in complex tech are hard to verify and depend on trust to the other side. Boeing really blew up the trust, not even by a bad design, but by not responding to accidents in good faith. So any assumptions made based on trust - quality of design, solid production practices, quality of software code, honesty of FAA designated representatives on Boring payroll - can and should be verified by third party. Trust is hard to earn, but easy to loose.
 
IADFCO
Posts: 117
Joined: Sun May 22, 2016 4:20 pm

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 2:39 am

I second what kalvado wrote, and add this: to this day we don't have a precise picture of the problem that MCAS is trying to address when in normal operation, let alone what may happen when it's malfunctioning. Sure, even just in this thread we have thousands of posts with pretty good ideas and a general sense, but nothing remotely approaching engineering quality data. The usual answer has been to trust FAA judgment that any problems have been understood and solved. I don't know whether that approach still works.

The MAX issue reminds me a bit of the V-22 problems a couple of decades ago. That program was very controversial (for some it still is) and there were tens of billions of dollars involved. Pilot error was a contributing factor, and so was physics (the vortex ring ring state). Twenty people died as a result of one accident and the aircraft was grounded for over a year. A big difference was that the program was military, so some of the pressure in lifting the grounding was missing.

Two important elements from that story, which could be relevant to the MAX issue:
1 - There was a thorough analysis of all available theoretical and experimental information available on the issue of vortex ring state for tilt rotors (for example, see here: https://ntrs.nasa.gov/?N=0&DocumentID=20060024029). For the MAX, the equivalent would be at least a thorough CFD analysis, and hopefully a wind tunnel test, of the nacelle/pylon/wing area. Even in the US this could be done with no Boeing or FAA involvement. For example, US Air Force, US Navy, and US Army, all have the necessary expertise to do analysis and test in their research labs, or to supervise outside contractors.

2 - There was a flight test campaign that explored in detail the behavior of the V-22 in portions of the flight and maneuver envelope near and inside the vortex ring state boundaries (for example, see here: https://vtol.org/04FEE0C0-E921-11E0-8A940050568D0042). This was carried out by Bell and Boeing pilots, but again, there is plenty of expertise in the US military to perform independent flight tests with no Boeing or FAA participation.

Very importantly, all the information above was made public, and presented in forums where it could be subjected to expert review. I suppose that lawyers (and lobbyists, since this was a military program with great US Congress involvement) were hard at work in that case as well. I think that the openness greatly helped the program. I don't know whether it changed any minds about the V-22 program itself, but certainly what happened and didn't happen, especially in the Marana accident, was much better understood, and so were the fixes.
 
ArgentoSystems
Posts: 298
Joined: Sun Mar 24, 2019 12:05 am

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 3:42 am

OldAeroGuy wrote:
kalvado wrote:

Because I'm afraid that MCAS is thirteenth strike of the clock - and now that one is worked out, but other twelve still need to be looked at.
I don't think MCAS specific training is on order once that issue is fixed, but that doesn't mean the rest of the plane is in a good shape. It may be, but maybe not. EASA and CAAC should inform Boeing and FAA about conclusions of their analysis.


Well, you've lost me with this one.

No real reason to complain after MCAS.v2 is approved, but you just don't like the airplane.

Very well, there is no way to use rational discussion against faith or superstition.

You are just not trying to see the reason.

I completely share his concern. Airplane is compromised, because at least in one part of it design process was totally broken. There is no reason to assume they followed solid design process in other aspects of the plane.
 
XT6Wagon
Posts: 2721
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 4:30 am

ArgentoSystems wrote:
OldAeroGuy wrote:
kalvado wrote:

Because I'm afraid that MCAS is thirteenth strike of the clock - and now that one is worked out, but other twelve still need to be looked at.
I don't think MCAS specific training is on order once that issue is fixed, but that doesn't mean the rest of the plane is in a good shape. It may be, but maybe not. EASA and CAAC should inform Boeing and FAA about conclusions of their analysis.


Well, you've lost me with this one.

No real reason to complain after MCAS.v2 is approved, but you just don't like the airplane.

Very well, there is no way to use rational discussion against faith or superstition.

You are just not trying to see the reason.

I completely share his concern. Airplane is compromised, because at least in one part of it design process was totally broken. There is no reason to assume they followed solid design process in other aspects of the plane.


So, best not fly on A320, A330, A380 then as certification for those missed critical defects. More over A320 is a warmed over 50 year old design, massively grandfathered to reduce certification costs. Best avoid that at all costs according to A.net. That horrible horrible A330 is still using a warmed over A300-600 fuselage design, that can't be good! Its so OLD!!!!

Or you know, you can look at the statistics that travel on large commercial aircraft is so safe that a single event is shocking and tragic. Regardless of who makes the aircraft.
 
jollo
Posts: 349
Joined: Mon Aug 08, 2011 7:24 pm

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 7:45 am

9Patch wrote:
jollo wrote:
MCAS (any version) operating on correct inputs is "invisible" to the pilot, so no training is needed. An inoperative MCAS v2 (because inputs are detected as incorrect, e.g. AoA disagree) would likely be no big deal for the pilot, just like an inoperative ABS is no big deal for a driver: you just have to know how to handle the vehicle without the control augmentation. For a driver, this means slow down on wet roads; for a pilot, this means a couple of new memory items (e.g. AoA limit at slow speed, bank angle limit at high speed, etc.).

THIS requires training.

But does it require simulator training?


If the NEW memory items (specific to the MAX without an operative MCAS) are deemed Level D differences then yes, a partial proficiency check using level 6 or higher FSTD is required.

Beyond mere adherence to regulations, IMO common sense would suggest that a pilot should sit in a simulator, observe the new, unfamiliar warning light, call out the required memory items and fly a few maneuvers in the affected flight regimes complying with the relevant limits. Nothing dramatic, nothing unexpected of a new type. I really don't understand how some members here seem to have adopted the "no sim training" mantra: simulator training exists for excellent reasons, it's not an evil to be avoided at all costs.
Last edited by jollo on Fri Apr 26, 2019 8:06 am, edited 2 times in total.
 
XRAYretired
Posts: 482
Joined: Fri Mar 15, 2019 11:21 am

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 8:04 am

XT6Wagon wrote:
ArgentoSystems wrote:
OldAeroGuy wrote:

Well, you've lost me with this one.

No real reason to complain after MCAS.v2 is approved, but you just don't like the airplane.

Very well, there is no way to use rational discussion against faith or superstition.

You are just not trying to see the reason.

I completely share his concern. Airplane is compromised, because at least in one part of it design process was totally broken. There is no reason to assume they followed solid design process in other aspects of the plane.


So, best not fly on A320, A330, A380 then as certification for those missed critical defects. More over A320 is a warmed over 50 year old design, massively grandfathered to reduce certification costs. Best avoid that at all costs according to A.net. That horrible horrible A330 is still using a warmed over A300-600 fuselage design, that can't be good! Its so OLD!!!!

Or you know, you can look at the statistics that travel on large commercial aircraft is so safe that a single event is shocking and tragic. Regardless of who makes the aircraft.

Shame on you trying to bring this back down to playground antics Apples v. Bananas. A whole barrel of rotten Apples does not justify a black Banana.

Shame on OAG for suggesting legitimately expressed concern is superstition. I am quite sure that Boeing/FAA will thoroughly review all other aspects of the MAX programme, if not already completed! and will review similar projects over recent years. This is what a responsible company would do. If they don't, I would suspect that they may well be instructed to do so by the government reviews already underway.

NB. On the subject of superstition. Boeing are the only entity I've ever been involved with who have rejected a software update for the one and simple reason that it was version 13. A further revision had to be made to 14 and that was the sole change.

Ray
 
Amiga500
Posts: 2236
Joined: Tue Mar 03, 2015 8:22 am

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 9:31 am

zeke wrote:
1- the flight control system neither failed or jammed
2- you have agreed that random crews could land the aircraft without exceptional skill or strength
3- both aircraft that crashed continued on their normal takeoff SID and only stated their intention to return when it was already too late. The ET crew even put the autopilot on with the stick shaker going. The aircraft that didn’t crash climbed up and did a hold to work the problem. But then went into its destination with the stick shaker activated.


Not being ignorant, but is English your first language?

1. failures in the flight control system =/= failed flight control system

2. I agree that in the instance:
I would like to think if you put 10 random 737 crews in a simulator and told them just after liftoff you are going to have a AOA failure, stick shaker will come on immediately. We want you to come back and land. I think all of the crews would have no problem getting the aircraft on the ground safely. It does not take any extra ordinary skill or strength.

They would probably be able to land the aircraft all right.

3. MCAS doesn't become active until flaps are lifted. Are you proposing they complete their circuit and landing without withdrawing flaps? Or that they hold above the airport with flaps down? What if they have taken off at MTOW and are above MLW? If you aren't willing to consider a procedure that deals with all instances - and instead are constructing a strawman argument to the specific crashes, then this discussion is not worth having.
 
Interested
Posts: 647
Joined: Thu May 19, 2016 12:19 pm

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 10:00 am

kalvado wrote:
OldAeroGuy wrote:
Here is why i believe you're wrong.

Training and adherence to check lists/procedures is required for every phase of airplane flight.

There are no evolved human traits that teach a pilot to rotate an airplane at the proper rate at VR or flare an airplane at the proper height for landing. It all comes from training.

Likewise, there are many failure conditions that a pilot must recognize and take the appropriate action. Most are single failures and many are memory items. Failures to take the correct action can result in hull loss and loss of life.

Examples:

- Engine failure below V1.
- Auto speed brake failure on either a refused wet takeoff or a contaminated runway landing
- Rapid decompression at cruise altitude
- Cargo compartment fire
- Flight with unreliable airspeed
- Runaway stabilizer trim

Just as you depend on crew training to successfully deal with all these failures, why would you feel that a properly trained crew would not be able to deal with an MCAS operating failure, particularly since MCAS.v2 will both decrease the likelihood of such a failure and limit possible MCAS failure mode action?

This applies to kalvados post as well.


Well, this an engineering psychology question. Humans make mistakes, that is their nature. If an engineer has to rely on trained human in emergency - they already lost most of situation control, it is now a lottery.

It is a very good practice to give people a chance to think and do things again if they fail after first try. If failure is not an option - drill, drill, drill. And it has to be straightforward situation to drill, and getting into that situation is already a high risk.
Engine out at V1, as far as I understand, is practiced often enough, and it is about very few symptoms, minimum diagnostics. How many rejected takeoffs didn't end up well?
Same with rapid decompression - once alarm sounds, better safe than sorry, you go down first diagnose later..
Problem of MCAS is that it required significant instant action (hold that damn yoke!) AND diagnostics of the issue is less than straightforward as it is a cascade failure. Specific indication is a bare minimum.
I bet even if you drill MCAS 1.0 response, success rate will be low, 90% at best. What's worse, since this high profile situation has to be drilled well enough to run on muscle memory - there will be false positives, when MCAS procedure will be called for even in non-MCAS scenario, and I am not ready to say if that would be a "better safe than sorry" case.

So what I am saying, threat of erroneous actuation has to be minimized, to at least 1e-8, with clear understanding that proper response will happen in 9 out of 10 cases if we're lucky.


The above is my concern. It's knowing there will be human error at some stage either from pilots or groundcrew maintaining anything needed to make MCAS work properly

Now if you guys are saying the software fix/patch will be so good it will mean MCAS going wrong will never be able to lead to a disaster again DESPITE HUMAN ERRORS above then that's fair enough

Because I'm just knowing there will be human error at some stage. Hence why I believe the correct policy is don't introduce new risks we don't need and don't create new opportunities for human error to lead to disasters

It really worries me when I'm reading more and better training can solve this problem

As to me that's relying on humans - and that's very risky as countless disasters in the past have shown

I would much rather a problem could never occur again from MCAS that human intervention needs to solve. It doesn't look like that's where we can end up does it?

In which case if another disaster occurs that MCAS contributes to then it's the initial design of a plane that needs this MCAS to fly that is at fault IMO

Not the humans that make any errors dealing with it

Hope that makes sense
 
ArgentoSystems
Posts: 298
Joined: Sun Mar 24, 2019 12:05 am

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 10:09 am

XT6Wagon wrote:
So, best not fly on A320, A330, A380 then as certification for those missed critical defects.

Not a very smart comment. For starters, get your facts straight. A320 is 30 year old.
 
User avatar
par13del
Posts: 8649
Joined: Sun Dec 18, 2005 9:14 pm

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 12:20 pm

kalvado wrote:
Why, it is simple. A lot of things in complex tech are hard to verify and depend on trust to the other side. Boeing really blew up the trust, not even by a bad design, but by not responding to accidents in good faith. So any assumptions made based on trust - quality of design, solid production practices, quality of software code, honesty of FAA designated representatives on Boring payroll - can and should be verified by third party. Trust is hard to earn, but easy to loose.

So to be clear, you are saying that the years of safe operation of the 737 in numerous countries by numerous airlines under various regulators has no bearing in the evaluation?
The fact that the FAA has outsourced some of it responsibility and that Boeing had shortfalls in the response to the MAX incidents indicates that numerous errors exist in the a/c that have been flying and now this incident will reveal all the errors that exits but were hidden by Boeing management?
Simplistic, but trying to understand the base logic.
 
kalvado
Posts: 1793
Joined: Wed Mar 01, 2006 4:29 am

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 12:28 pm

par13del wrote:
kalvado wrote:
Why, it is simple. A lot of things in complex tech are hard to verify and depend on trust to the other side. Boeing really blew up the trust, not even by a bad design, but by not responding to accidents in good faith. So any assumptions made based on trust - quality of design, solid production practices, quality of software code, honesty of FAA designated representatives on Boring payroll - can and should be verified by third party. Trust is hard to earn, but easy to loose.

So to be clear, you are saying that the years of safe operation of the 737 in numerous countries by numerous airlines under various regulators has no bearing in the evaluation?
The fact that the FAA has outsourced some of it responsibility and that Boeing had shortfalls in the response to the MAX incidents indicates that numerous errors exist in the a/c that have been flying and now this incident will reveal all the errors that exits but were hidden by Boeing management?
Simplistic, but trying to understand the base logic.

I am saying that full details about differences between NG and MAX are not shown. There are, besides new engines, apparently some changes in the electronics compartment, and most likely software modification. Looks like many small things could be downplayed. We're hopefully done with items bringing 100x higher than NG crash rate. items which may result in 10x NG crash rate may still to be discovered - and better do that in the office than while sorting through debris.
As for NG... If we want to move forward, the existing safety record is not the reason not to look back. Analysis of NG risk analysis in light of trim wheel limited functionality is another must-do item.
 
JHwk
Posts: 560
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 12:44 pm

Proper evaluation of MCAS 2.x requires a specific definition of the flight envelope that it is intended to operate in. So far, it is unclear what Boeing is doing to validate sensor data beyond “disagree,” which might not be quite enough given the high failure rate on the AoA sensors.
 
Jamie514
Posts: 139
Joined: Thu May 18, 2017 4:36 pm

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 1:15 pm

par13del wrote:
kalvado wrote:
Why, it is simple. A lot of things in complex tech are hard to verify and depend on trust to the other side. Boeing really blew up the trust, not even by a bad design, but by not responding to accidents in good faith. So any assumptions made based on trust - quality of design, solid production practices, quality of software code, honesty of FAA designated representatives on Boring payroll - can and should be verified by third party. Trust is hard to earn, but easy to loose.

So to be clear, you are saying that the years of safe operation of the 737 in numerous countries by numerous airlines under various regulators has no bearing in the evaluation?
The fact that the FAA has outsourced some of it responsibility and that Boeing had shortfalls in the response to the MAX incidents indicates that numerous errors exist in the a/c that have been flying and now this incident will reveal all the errors that exits but were hidden by Boeing management?
Simplistic, but trying to understand the base logic.


NG safety record is a strawman argument in light of the significant changes introduced.

The complete lack of transparency and insight to the problematic design and certification of the current model offers no assurance there aren't further issues.

To suggest "MCAS has been corrected and the MAX is a development of the NG so therefore we know the rest of the plane is safe" is making many assumptions about what Boeing did and didn't change. You can't possibly draw that conclusion with the information at hand.

And I think you know that.
 
morrisond
Posts: 1173
Joined: Thu Jan 07, 2010 12:22 am

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 1:18 pm

Interested wrote:
kalvado wrote:
OldAeroGuy wrote:
Here is why i believe you're wrong.

Training and adherence to check lists/procedures is required for every phase of airplane flight.

There are no evolved human traits that teach a pilot to rotate an airplane at the proper rate at VR or flare an airplane at the proper height for landing. It all comes from training.

Likewise, there are many failure conditions that a pilot must recognize and take the appropriate action. Most are single failures and many are memory items. Failures to take the correct action can result in hull loss and loss of life.

Examples:

- Engine failure below V1.
- Auto speed brake failure on either a refused wet takeoff or a contaminated runway landing
- Rapid decompression at cruise altitude
- Cargo compartment fire
- Flight with unreliable airspeed
- Runaway stabilizer trim

Just as you depend on crew training to successfully deal with all these failures, why would you feel that a properly trained crew would not be able to deal with an MCAS operating failure, particularly since MCAS.v2 will both decrease the likelihood of such a failure and limit possible MCAS failure mode action?

This applies to kalvados post as well.


Well, this an engineering psychology question. Humans make mistakes, that is their nature. If an engineer has to rely on trained human in emergency - they already lost most of situation control, it is now a lottery.

It is a very good practice to give people a chance to think and do things again if they fail after first try. If failure is not an option - drill, drill, drill. And it has to be straightforward situation to drill, and getting into that situation is already a high risk.
Engine out at V1, as far as I understand, is practiced often enough, and it is about very few symptoms, minimum diagnostics. How many rejected takeoffs didn't end up well?
Same with rapid decompression - once alarm sounds, better safe than sorry, you go down first diagnose later..
Problem of MCAS is that it required significant instant action (hold that damn yoke!) AND diagnostics of the issue is less than straightforward as it is a cascade failure. Specific indication is a bare minimum.
I bet even if you drill MCAS 1.0 response, success rate will be low, 90% at best. What's worse, since this high profile situation has to be drilled well enough to run on muscle memory - there will be false positives, when MCAS procedure will be called for even in non-MCAS scenario, and I am not ready to say if that would be a "better safe than sorry" case.

So what I am saying, threat of erroneous actuation has to be minimized, to at least 1e-8, with clear understanding that proper response will happen in 9 out of 10 cases if we're lucky.


The above is my concern. It's knowing there will be human error at some stage either from pilots or groundcrew maintaining anything needed to make MCAS work properly

Now if you guys are saying the software fix/patch will be so good it will mean MCAS going wrong will never be able to lead to a disaster again DESPITE HUMAN ERRORS above then that's fair enough

Because I'm just knowing there will be human error at some stage. Hence why I believe the correct policy is don't introduce new risks we don't need and don't create new opportunities for human error to lead to disasters

It really worries me when I'm reading more and better training can solve this problem

As to me that's relying on humans - and that's very risky as countless disasters in the past have shown

I would much rather a problem could never occur again from MCAS that human intervention needs to solve. It doesn't look like that's where we can end up does it?

In which case if another disaster occurs that MCAS contributes to then it's the initial design of a plane that needs this MCAS to fly that is at fault IMO

Not the humans that make any errors dealing with it

Hope that makes sense


Well the bizarre thing is MCAS isn't really needed to make the MAX safe - it's just needed MCAS to meet a specific regulation that the MAX was barely over on. I don't think anyone can conceive that an MAX without MCAS would be unsafe and lead to crashes as even the worst trained pilots would recognize they are about to stall the aircraft and take simple corrective action(push control column forward).

However since MCAS is needed to meet certification requirements - You are making the argument that I have been making for weeks now.

Yes parts in the MCAS can fail - leading to the crew having to perform procedures to save the plane.

Just like parts in any other Aircraft can fail and lead to the Pilots having to perform procedures to save the plane.

You can't design an aircraft to be totally redundant to the point where any or multiple systems can fail and the crew does not need to intervene.

As long as you have the backup Instrument with Airspeed, Altitude and Atitude (which rely on seperate sources than the primary instruments and have there own backup batteries) - no commercial airplane is that hard to fly without the nannies and does not require exceptional skills. If you are a pilot and not able to fly an Airplane in Manual mode and control it's airspeed, pitch and roll you should not be in the cockpit.

Until AI gets good enough to replace a Pilot - we will have Pilots - and if you want fewer disasters start advocating for better training. Parts will fail - Crews will have to intervene.
 
morrisond
Posts: 1173
Joined: Thu Jan 07, 2010 12:22 am

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 1:26 pm

XRAYretired wrote:
XT6Wagon wrote:
ArgentoSystems wrote:
You are just not trying to see the reason.

I completely share his concern. Airplane is compromised, because at least in one part of it design process was totally broken. There is no reason to assume they followed solid design process in other aspects of the plane.


So, best not fly on A320, A330, A380 then as certification for those missed critical defects. More over A320 is a warmed over 50 year old design, massively grandfathered to reduce certification costs. Best avoid that at all costs according to A.net. That horrible horrible A330 is still using a warmed over A300-600 fuselage design, that can't be good! Its so OLD!!!!

Or you know, you can look at the statistics that travel on large commercial aircraft is so safe that a single event is shocking and tragic. Regardless of who makes the aircraft.

Shame on you trying to bring this back down to playground antics Apples v. Bananas. A whole barrel of rotten Apples does not justify a black Banana.

Shame on OAG for suggesting legitimately expressed concern is superstition. I am quite sure that Boeing/FAA will thoroughly review all other aspects of the MAX programme, if not already completed! and will review similar projects over recent years. This is what a responsible company would do. If they don't, I would suspect that they may well be instructed to do so by the government reviews already underway.

NB. On the subject of superstition. Boeing are the only entity I've ever been involved with who have rejected a software update for the one and simple reason that it was version 13. A further revision had to be made to 14 and that was the sole change.

Ray


Shame on Ray for calling me out Yesterday and then not replying to my response #5995

Apologies if you didn't see it.
 
IADFCO
Posts: 117
Joined: Sun May 22, 2016 4:20 pm

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 1:41 pm

morrisond wrote:

Well the bizarre thing is MCAS isn't really needed to make the MAX safe - it's just needed MCAS to meet a specific regulation that the MAX was barely over on. I don't think anyone can conceive that an MAX without MCAS would be unsafe and lead to crashes as even the worst trained pilots would recognize they are about to stall the aircraft and take simple corrective action(push control column forward).


"MCAS isn't really needed to make the MAX safe": how do you know? and based on what definition of "safe"? one accident with loss of aircraft and loss of life every 10 flights? 10^3? 10^5? 10^9?

"it's just needed MCAS to meet a specific regulation that the MAX was barely over on": how do you know? and what does "barely" mean? based on what metrics?

Personal opinions are always interesting, but some link to factual information would be even more interesting and appreciated.
 
ArgentoSystems
Posts: 298
Joined: Sun Mar 24, 2019 12:05 am

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 1:48 pm

IADFCO wrote:
"MCAS isn't really needed to make the MAX safe": how do you know? and based on what definition of "safe"? one accident with loss of aircraft and loss of life every 10 flights? 10^3? 10^5? 10^9?

"it's just needed MCAS to meet a specific regulation that the MAX was barely over on": how do you know? and what does "barely" mean? based on what metrics?

Personal opinions are always interesting, but some link to factual information would be even more interesting and appreciated.


Some people stubbornly persist in a delusion that it is some random regulation that exists for no reason.
 
morrisond
Posts: 1173
Joined: Thu Jan 07, 2010 12:22 am

Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 2:08 pm

IADFCO wrote:
morrisond wrote:

Well the bizarre thing is MCAS isn't really needed to make the MAX safe - it's just needed MCAS to meet a specific regulation that the MAX was barely over on. I don't think anyone can conceive that an MAX without MCAS would be unsafe and lead to crashes as even the worst trained pilots would recognize they are about to stall the aircraft and take simple corrective action(push control column forward).


"MCAS isn't really needed to make the MAX safe": how do you know? and based on what definition of "safe"? one accident with loss of aircraft and loss of life every 10 flights? 10^3? 10^5? 10^9?

"it's just needed MCAS to meet a specific regulation that the MAX was barely over on": how do you know? and what does "barely" mean? based on what metrics?

Personal opinions are always interesting, but some link to factual information would be even more interesting and appreciated.


Please look back through the last couple of pages - The MAX missed the stick force gradient by just a few pounds of column force.

Neither accident would have happened without MCAS and there would have been no fatalities if it did not exist.

How many MAX's or NG have gotten into a stall and caused loss of life? Or any other Commercial aircraft in many years? Except for Colgan - which had icing and the pilot applied the wrong procedure - pulling back vs pushing forward.

You are basically arguing that a Pilot can't even identify a plane is going into a stall. If training is that bad or you arguing that a pilot shouldn't have to be able to identify a stall or how to recover from it then we are in big trouble if that is what standards have fallen too and pilots are way overpaid then.
 
morrisond
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 2:15 pm

ArgentoSystems wrote:
IADFCO wrote:
"MCAS isn't really needed to make the MAX safe": how do you know? and based on what definition of "safe"? one accident with loss of aircraft and loss of life every 10 flights? 10^3? 10^5? 10^9?

"it's just needed MCAS to meet a specific regulation that the MAX was barely over on": how do you know? and what does "barely" mean? based on what metrics?

Personal opinions are always interesting, but some link to factual information would be even more interesting and appreciated.


Some people stubbornly persist in a delusion that it is some random regulation that exists for no reason.


It exists for a reason - to help the Pilot notice they are getting close to a stall - but then you have the stick shaker, the audio warnings and the frame buffeting all before the stall. No pilot no matter how poorly trained would miss those, you don't go from no stall to full stall in a Bus(meaning a non agile aircraft) like a 737 in a split second - it takes quite bit of time and develops over 10-20 seconds even if you really intentionally try to enter one - in which time you have the previously mentioned warnings above telling you to stop doing what you are doing.

It's a good idea - but in reality it does not nothing to make the MAX safer. Although not allowed by regulation - the iPad converison course could have had a page that simply said "At full aft COG and very light weights - the controls might get a little light as you approach stall."
 
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SomebodyInTLS
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 2:25 pm

morrisond wrote:
It exists for a reason - to help the Pilot notice they are getting close to a stall


You keep sticking to this - but that is only what MCAS was *ostensibly* for *before flight test*! That doesn't explain why authority changed from 0.6 units to 2.5 units trim - which would indicate that stability (that word) was worse than expected and MCAS became a workaround to avoid implementing a better but more costly (training, paperwork) solution.

The rules and purpose appear to have changed between the relatively benign system presented to customers and the authorities and what was actually put into production.
"As with most things related to aircraft design, it's all about the trade-offs and much more nuanced than A.net likes to make out."
 
MSPNWA
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 2:38 pm

SomebodyInTLS wrote:
You keep sticking to this - but that is only what MCAS was *ostensibly* for *before flight test*! That doesn't explain why authority changed from 0.6 units to 2.5 units trim - which would indicate that stability (that word) was worse than expected and MCAS became a workaround to avoid implementing a better but more costly (training, paperwork) solution.

The rules and purpose appear to have changed between the relatively benign system presented to customers and the authorities and what was actually put into production.


Being changed from 0.6 units to 2.5 units isn't incongruent with that theory. It only implies that more automatic trim input was needed to meet regulation.
 
morrisond
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 2:44 pm

SomebodyInTLS wrote:
morrisond wrote:
It exists for a reason - to help the Pilot notice they are getting close to a stall


You keep sticking to this - but that is only what MCAS was *ostensibly* for *before flight test*! That doesn't explain why authority changed from 0.6 units to 2.5 units trim - which would indicate that stability (that word) was worse than expected and MCAS became a workaround to avoid implementing a better but more costly (training, paperwork) solution.

The rules and purpose appear to have changed between the relatively benign system presented to customers and the authorities and what was actually put into production.


Who knows - but until someone presents some evidence that the MAX is unstable for some other reason - it may have simply been they guessed wrong on how much intervention was needed in a short period of time to get the required stick force gradient. .6 units of trim really does not seem like a lot.

You would have to have a pretty fantastic CFD model to figure this out without flight test. That is why they have flight test.
 
kalvado
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 2:45 pm

MSPNWA wrote:
SomebodyInTLS wrote:
You keep sticking to this - but that is only what MCAS was *ostensibly* for *before flight test*! That doesn't explain why authority changed from 0.6 units to 2.5 units trim - which would indicate that stability (that word) was worse than expected and MCAS became a workaround to avoid implementing a better but more costly (training, paperwork) solution.

The rules and purpose appear to have changed between the relatively benign system presented to customers and the authorities and what was actually put into production.


Being changed from 0.6 units to 2.5 units isn't incongruent with that theory. It only implies that more automatic trim input was needed to meet regulation.

It implies much more force had to be added, and few tens pounds can be a more realistic estimate for the force requirements. WHich, again, brings up question if a small blip in stick force was actually potential rolloff faster than expected. Questions about wind tunnel tests, and ability to interpret them are on order.
At this point, there is very little about MAX which cannot be reasonably questioned. And Boeing doesn't do anything to qnswer these questions.. Sounds like they are in survival mode.
 
Interested
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 2:48 pm

kalvado wrote:
par13del wrote:
kalvado wrote:
Why, it is simple. A lot of things in complex tech are hard to verify and depend on trust to the other side. Boeing really blew up the trust, not even by a bad design, but by not responding to accidents in good faith. So any assumptions made based on trust - quality of design, solid production practices, quality of software code, honesty of FAA designated representatives on Boring payroll - can and should be verified by third party. Trust is hard to earn, but easy to loose.

So to be clear, you are saying that the years of safe operation of the 737 in numerous countries by numerous airlines under various regulators has no bearing in the evaluation?
The fact that the FAA has outsourced some of it responsibility and that Boeing had shortfalls in the response to the MAX incidents indicates that numerous errors exist in the a/c that have been flying and now this incident will reveal all the errors that exits but were hidden by Boeing management?
Simplistic, but trying to understand the base logic.

I am saying that full details about differences between NG and MAX are not shown. There are, besides new engines, apparently some changes in the electronics compartment, and most likely software modification. Looks like many small things could be downplayed. We're hopefully done with items bringing 100x higher than NG crash rate. items which may result in 10x NG crash rate may still to be discovered - and better do that in the office than while sorting through debris.
As for NG... If we want to move forward, the existing safety record is not the reason not to look back. Analysis of NG risk analysis in light of trim wheel limited functionality is another must-do item.


Bearing in mind that early on in the Ethiopia crash investigation they found a second fault with something that needed fixing he may have a point

Regardless there's enough issues trying to reduce the MCAS risk as much as possible

Was nose down 2.5 more than once a mistake or did they choose that to happen for a reason when they first designed the plane

Do we also lose some safety when that only happens once in the future?
 
Interested
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 2:52 pm

morrisond wrote:
Interested wrote:
kalvado wrote:

Well, this an engineering psychology question. Humans make mistakes, that is their nature. If an engineer has to rely on trained human in emergency - they already lost most of situation control, it is now a lottery.

It is a very good practice to give people a chance to think and do things again if they fail after first try. If failure is not an option - drill, drill, drill. And it has to be straightforward situation to drill, and getting into that situation is already a high risk.
Engine out at V1, as far as I understand, is practiced often enough, and it is about very few symptoms, minimum diagnostics. How many rejected takeoffs didn't end up well?
Same with rapid decompression - once alarm sounds, better safe than sorry, you go down first diagnose later..
Problem of MCAS is that it required significant instant action (hold that damn yoke!) AND diagnostics of the issue is less than straightforward as it is a cascade failure. Specific indication is a bare minimum.
I bet even if you drill MCAS 1.0 response, success rate will be low, 90% at best. What's worse, since this high profile situation has to be drilled well enough to run on muscle memory - there will be false positives, when MCAS procedure will be called for even in non-MCAS scenario, and I am not ready to say if that would be a "better safe than sorry" case.

So what I am saying, threat of erroneous actuation has to be minimized, to at least 1e-8, with clear understanding that proper response will happen in 9 out of 10 cases if we're lucky.


The above is my concern. It's knowing there will be human error at some stage either from pilots or groundcrew maintaining anything needed to make MCAS work properly

Now if you guys are saying the software fix/patch will be so good it will mean MCAS going wrong will never be able to lead to a disaster again DESPITE HUMAN ERRORS above then that's fair enough

Because I'm just knowing there will be human error at some stage. Hence why I believe the correct policy is don't introduce new risks we don't need and don't create new opportunities for human error to lead to disasters

It really worries me when I'm reading more and better training can solve this problem

As to me that's relying on humans - and that's very risky as countless disasters in the past have shown

I would much rather a problem could never occur again from MCAS that human intervention needs to solve. It doesn't look like that's where we can end up does it?

In which case if another disaster occurs that MCAS contributes to then it's the initial design of a plane that needs this MCAS to fly that is at fault IMO

Not the humans that make any errors dealing with it

Hope that makes sense


Well the bizarre thing is MCAS isn't really needed to make the MAX safe - it's just needed MCAS to meet a specific regulation that the MAX was barely over on. I don't think anyone can conceive that an MAX without MCAS would be unsafe and lead to crashes as even the worst trained pilots would recognize they are about to stall the aircraft and take simple corrective action(push control column forward).

However since MCAS is needed to meet certification requirements - You are making the argument that I have been making for weeks now.

Yes parts in the MCAS can fail - leading to the crew having to perform procedures to save the plane.

Just like parts in any other Aircraft can fail and lead to the Pilots having to perform procedures to save the plane.

You can't design an aircraft to be totally redundant to the point where any or multiple systems can fail and the crew does not need to intervene.

As long as you have the backup Instrument with Airspeed, Altitude and Atitude (which rely on seperate sources than the primary instruments and have there own backup batteries) - no commercial airplane is that hard to fly without the nannies and does not require exceptional skills. If you are a pilot and not able to fly an Airplane in Manual mode and control it's airspeed, pitch and roll you should not be in the cockpit.

Until AI gets good enough to replace a Pilot - we will have Pilots - and if you want fewer disasters start advocating for better training. Parts will fail - Crews will have to intervene.


But this plane requires more parts to fly that can fail due to its design?

That's a recipe for disaster IMO

We've increased the risk for the pilots, the groundcrew and us the passengers

I still can't find it acceptable that we've ended up with a more risky plane when it's due to be such an important plane

It's madness. Should never have got to this.
 
Interested
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 2:55 pm

IADFCO wrote:
morrisond wrote:

Well the bizarre thing is MCAS isn't really needed to make the MAX safe - it's just needed MCAS to meet a specific regulation that the MAX was barely over on. I don't think anyone can conceive that an MAX without MCAS would be unsafe and lead to crashes as even the worst trained pilots would recognize they are about to stall the aircraft and take simple corrective action(push control column forward).


"MCAS isn't really needed to make the MAX safe": how do you know? and based on what definition of "safe"? one accident with loss of aircraft and loss of life every 10 flights? 10^3? 10^5? 10^9?

"it's just needed MCAS to meet a specific regulation that the MAX was barely over on": how do you know? and what does "barely" mean? based on what metrics?

Personal opinions are always interesting, but some link to factual information would be even more interesting and appreciated.


With a future 25,000 plus flights a day - barely ever might happen far too often?
Last edited by Interested on Fri Apr 26, 2019 2:59 pm, edited 1 time in total.
 
MSPNWA
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Re: B737MAX Grounded Worldwide

Fri Apr 26, 2019 2:58 pm

kalvado wrote:
It implies much more force had to be added, and few tens pounds can be a more realistic estimate for the force requirements. WHich, again, brings up question if a small blip in stick force was actually potential rolloff faster than expected. Questions about wind tunnel tests, and ability to interpret them are on order.
At this point, there is very little about MAX which cannot be reasonably questioned. And Boeing doesn't do anything to qnswer these questions.. Sounds like they are in survival mode.


And this is an issue how?

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