Boeing 737 Max design error

trader4@optonline.net wrote in news:05600865-8e6b-40f9-bb09-
a6579ff820ad@googlegroups.com:

For guys like you we have the cutter offer option. A giant shear
that severs it.

Again, you retarded piece of shit... YOU represent exactly ZERO
"we" elements. You are part of no "we" except that of your multiple
wee brained personalities.

A secondarily, I do not need a primer on fail mode mechanisms from a
fat assed trader reject fucktard like you.

 

trader4@optonline.net wrote in news:05600865-8e6b-40f9-bb09-
a6579ff820ad@googlegroups.com:

Always wrong, and most times like this silly too.

You keep sporting those maturity issues, little boy. You are so
fucking obsessed that you cannot even write full, much less correct
sentences.

You are a fucking joke, TraderTard4.

 

On Tuesday, May 7, 2019 at 8:20:34 AM UTC-4, Sylvia Else wrote:

On 7/05/2019 9:38 pm, DecadentLinuxUserNumeroUno@decadence.org wrote:
Lasse Langwadt Christensen <langwadt@fonz.dk> wrote in
news:466ef7dc-0503-4b47-8485-71d8825dd7c5@googlegroups.com:

The biggest issue to me is that there was no release switch to
return
pilot control.

there is, two switches to turn off electric trim and the pilots
are supposed to know how to handle run away trim by memory


I know what is there. You do not understand my statement.

I do not like an actuator arm locked onto my elevator. That
removes my control and an emergency cicumstance does not restore
control, it merely gives up as the controlling element. The pilot
still then must manually actuate a mecahnism at a much slower rate
than needed, to get back to stick control.

If there is one, it needs to have a FULL release and not be a
manual screw requiring manual return. If it gets released fully,
the pilot's elevator control return is a mere stick push.


The trim is a normal part of the aircraft's control system, and it
doesn't have a fixed correct position to which it could be restored. It
has to be adjusted frequently during the flight depending on many
factors. In the 737, the trim is adjusted by having the tailplane driven
by a jackscrew. The only way that the trim can be restored to its
currently correct state after something has driven wrongly it is to turn
the jackscrew the other way. Once you've disabled the power to the
jackscrew motor, human power is the only way it can be done.

I may be wrong, but I believe there is still hydraulic assist or similar
to the jackscrew for a number of reasons, one of which is that you could
not exert enough force to turn it by hand. I think the electric cutoff
to the trim disables a small motor that moves the trim wheels, which in
turn drive the motor that moves the jackscrew.

Anything more complicated just introduces other failure modes, and as
has been abundantly demonstrated, you don't want things messing with the
position of the tailplane.

Sylvia.

That's for sure.

 

On Tuesday, May 7, 2019 at 8:10:58 AM UTC-4, Sylvia Else wrote:

On 7/05/2019 9:15 pm, DecadentLinuxUserNumeroUno@decadence.org wrote:
trader4@optonline.net wrote in
news:bc496342-1823-4eb9-9b07-ab96aae6321f@googlegroups.com:


Incorrect. There are two clearly marked cutoff switches for the
electric trim, located right at the large trim wheels that are
spinning back and forth beside the pilots. Turned off, MCAS can't
do anything.



The problem is that when finally turned off, the movement MCAS
ALREADY DID perform placed the tail in an unstable position, and
required a SLOW, MANUAL, PILOT INITIATED RETURN.

There needs to be a system that once deativated, allow full IMMEDIATE
restore of pilot control, WITHOUT a SLOW, MANUAL EFFECTOR POSITION
MOVEMENT REQIUISITE.


The problem here is that you're talking about another piece of equipment
that can control the trim, and which might do so when it shouldn't.

Bingo. And to fix a mostly non-existent problem. It's almost certain
that another add-on, which would add cost and complexity, would reduce
reliability, not increase it. Electric trim, the cutoff switches,
trimming manually has been around for a very long time and I'd like
to see data that shows what he wants would have made any difference.

 

On Tuesday, May 7, 2019 at 7:48:09 AM UTC-4, DecadentLinux...@decadence.org wrote:

bitrex <user@example.net> wrote in news:Vy_zE.16$s85.5@fx34.iad:


I propose a psychological phenomena called "Transient Reactive
Incompetence" - when faced with a combination of unfamiliar
situation or high stress levels, and presented with a set of
options, humans will tend to pick the least advantageous options
despite the information they already know that suggests to do
otherwise



In that case no human should be piloting any passenger plane. It
should all be computers.

We seem to be slowly evolving there.

No. SOME humans are really bad in panic situations and they do
panic. Some humans react differntly to panic situations.

We know that most of the pilots presented with runaway trim on the Max
couldn't identify it and follow the simple procedure. One pilot for
sure did, probably two, but two out of seven isn't very reassuring.

 

[Sylvia Else]

On 7/05/2019 11:13 pm, DecadentLinuxUserNumeroUno@decadence.org wrote:

Sylvia Else <sylvia@email.invalid> wrote in
news:gjdbgdFo8vtU1@mid.individual.net:


The trim is a normal part of the aircraft's control system, and it
doesn't have a fixed correct position to which it could be
restored. It has to be adjusted frequently during the flight
depending on many factors.

You are confusing aircraft basic elements.

trim tabs are small portions of flight surfaces.

Who mentioned trim tabs?

Anyway, I don't know where you're getting that from. Different aircraft
use different arrangements for longitudinal trim. The trim on a 737
works by adjusting the tailplane.

The MCAS system here moves the entire elevator on the plane.

It doesn't touch the elevators.

Sylvia.

 

[Martin Brown]

On 07/05/2019 08:17, Jasen Betts wrote:

On 2019-05-07, Riley Angel <4736angel@pm.me> wrote:
On 2019-05-06 06:42, Jan Panteltje wrote:
I have read lately it was, it is anyways in the sense that it did not detect the output to ever tilt the thing more and more.
Looks like the dumbest loop you can ever write.
It did not check angular position (I think they added that now, only takes a 1$ MEMS chip),
and it had no redundancy.

They already had an artificial horizon. The thing that was missing was
any kind of sanity check on the validity of the AoA sensor output.

There was also a major discrepancy between what Boeing told the FAA MCAS
would do in terms of how much adjustment and what it did in actuality.
This is unforgivable at multiple levels. No-one will ever trust the FAA
again outside of the USA. They were in bed with Boeing and prepared to
keep planes flying they knew to be dodgy even after the second crash.

Finally Boeing have been forced to admit they knew about this problem
and the AoA vulnerability more than a year before the first crash but
had convinced themselves that it wasn't a safety critical problem.

https://www.bbc.co.uk/news/business-48174797

Apparently they said "it did not jeopardise flight safety" which is true
in normal operation but completely untrue when the dodgy AoA sensor goes
haywire and MCAS puts the plane into an almost unrecoverable power dive.

It is an example of the fix being far more dangerous than the original
problem that it was supposed to address.

Swing a $1 MEMS chip round your head. Which angular position is which
now? An aircraft in flight is essentially a free body with only gravity
as a reference, which can be confused by any other sort of acceleration
force.

It's worse than that. An aircraft in flight does not have gravity as a
reference, what keeps you in your seat is the reaction to lift, and
lift is perpendicular to the wings, not the ground.

That said whilst the GPS system is working you also have some pretty
good independent numbers for ground speed and rate of climb that are
reliable and are referenced to an external reference frame. Airspeed
indicators have been known to cause crashes when they malfunction too
but they can also provide a sanity check against the risk of stalling.

I think there probably are flight configurations where you can pretty
much rule out stalling altogether. Notably when the nose is pointing
down and the plane is already gaining speed by losing height.

Since the problem only arises in normal flight mode I am surprised that
the SOP for zapping MCAS misbehaviour on take-off was not to extend
flaps again and increase engine thrust - then you get the benefit of
full servo control of all the flight surfaces and MCAS is disabled.

I am sure that eventually the story will come out how this thing was
certified as "airworthy" despite having such very obvious flaws.

--
Regards,
Martin Brown

 

[Riley Angel]

On 2019-05-07 03:56, Martin Brown wrote:

On 07/05/2019 05:17, Riley Angel wrote:
On 2019-05-06 06:46, trader4@optonline.net wrote:

The issue with the 737 Max is that at high levels of AOA, the plane has
a tendency to nose up even further.  Part of the certification process
is that if you release the controls the plane is supposed to head in
a stable direction, not toward instability.  That is why MCAS was added.

This is incorrect.

In what way is it incorrect? His description is a fairly succinct
explanation of the problem that MCAS was intended to address. Namely
that the physically bigger engines and shifted centre of gravity made
the plane tend towards an AoA stall condition if left to its own
devices. (but only in some fairly rare edge cases)

This is also incorrect

There are no CoG problems with 737 Max 8, or stability problems, or
anything else of that ilk which the press seem to be peddling with abandon.
It is true that it has larger engines whch are mounted further aft and
higher, but the essential problem is that the nacelles are larger and
generate more lift, particularly at higher AoA. This compounds the
pitch/thrust moment that the 737 classic is also known for, which is a
tendency for the aircraft to generate higher AoA itself through thrust
rather than control surfaces, although who knows if the higher engine
mounting position actually ameliorates that by reducing the length of
the moment arm.

MCAS is described as a safety feature, but all it was intended to do is
ensure that at higher angles of attack, the elevator /feel/ does not
change to make less elevator input force (stick back) required at high
AoA. It is not designed to save the airframe in some way from bad
piloting, in the same way that the stick-shaker stall warning won't
cause thrust to be applied or nose-up command inputs to be made without
the pilot performing those actions.

This is a fundamental point; the Max 8 is a completely new aircraft but
with similar enough flight controls to the preceding 737 that aviation
authorities, particularly the FAA, were willing to certify it as being
flyable by existing pilots without major type training, or as it turns
out, allow Boeing to self-certify large parts of a completely new design
to that end. That the controls simply perform the same way as pilots are
used to and are required by certain regulations was presumably a major
consideration in the instigation of MCAS in the first place.

It is simply unfortunate that some people got too far out of their box
and allowed the unit to have far more authority than it needed to
perform that function, and the design was a piece of crap with single
points of failure.

 

[Tauno Voipio]

On 7.5.19 14:41, DecadentLinuxUserNumeroUno@decadence.org wrote:

Tom Gardner <spamjunk@blueyonder.co.uk> wrote in
news:Gb_zE.286379$da5.124498@fx13.am4:

On 06/05/19 15:26, trader4@optonline.net wrote:
Altitude would not seem to be a parameter in determining if the
plane is stalling or not.

You can stall a plane at any attitude and any speed.
I've done that, many times.

It is particularly intense when you enter a spin
at 100ft AGL.



Was it in a multi-Decaton aircraft?

Define all these declarations to the parameters of flight we are
going to be seeing these craft involved in.

"enter a spin"? Please.

It is completely possible. A spin is a half-stall: The inside
wing is stalled and the outside wing still has lift.

--

-TV

 

[bitrex]

On 5/7/19 6:24 AM, DecadentLinuxUserNumeroUno@decadence.org wrote:

gnuarm.deletethisbit@gmail.com wrote in
news:f89a7717-773a-46e9-94a2-587ec64b5ca3@googlegroups.com:

On Monday, May 6, 2019 at 3:52:38 AM UTC-4, bitrex wrote:
On 5/6/19 3:28 AM, Jan Panteltje wrote:
On a sunny day (Sun, 5 May 2019 23:13:13 -0700) it happened
Banders <snap@mailchute.com> wrote in
qaoj9p$1jpn$1@gioia.aioe.org>:

On 05/05/2019 08:25 PM, omnilobe@gmail.com wrote:
Weight and Balance of the 737 Max.

I looked at photos of 737 and 737 Max. The 737 has the front
of the engine at the front of the wing. The Max has the rear
of the engine at the front of the wing. That makes it stall
easily.
Actually, tail-heavy makes for an easy stall, and nose-heavy
makes for a dive. The crash planes weren't stalling, the AOA
sensors just thought they were. So you have it backward.

This photo should put your mind at ease.
https://www.colombotelegraph.com/wp-
content/uploads/2019/03/Cr
ash-Animation-of-Ethiopian-Airlines-flight-ET302-Boeing-737-
Max
-pl ane.jpg

Normally software is tested and debugged, crashes happen,
bit of a nono to debug it in flights that carry people.

My opinion is that such software should be written by pilots,
not by spaced out no flying experience people.

I have bluntly refused to write code for things that I could
not use myself.

Ever write the code for an artificially intelligent sex-robot
that replicates the sensation of making love to a barely-legal
Asian college student majoring in microbiology? Asking for a
friend.

You are too funny! "Asking for a friend"... lol

So are these really available??? Instead of microbiology, do they
come in liberal arts majors? Asking for a friend...


This group does not give any friends away. They must be earned.
And then too, the very definition of the word is askew here.

So do not bother to ask for a friend, because they are rarely
available by request.

I don't actually like my women to come with owners/instruction manuals.
Where's the fun in that?

 

On Tuesday, May 7, 2019 at 9:25:39 AM UTC-4, DecadentLinux...@decadence.org wrote:

trader4@optonline.net wrote in
news:c3425dd2-d12c-46e5-a123-b6b50690dac9@googlegroups.com:


And how many more failure modes do you think that will introduce,
trying to solve a problem that Boeing already has the solution to?


Go away, little boy. You keep answering my posts as if I speak of
what IS in place, when clearly your inablity to interpret what you read
is glaring as I have been talking about what I think SHOULD BE in
place.

God DAMN, you are stupid, you putz motherfucker.

That's what we were talking about, your silly proposal for yet another
bandaid, your cutter offer. Since you claim that the existing mechanical
trim and the runaway trim procedure is totally inadequate, please provide
us the accident data over the last 50 years that supports that.

 

On Tuesday, May 7, 2019 at 9:04:07 AM UTC-4, DecadentLinux...@decadence.org wrote:

Sylvia Else <sylvia@email.invalid> wrote in news:gjdaubFo46rU1
@mid.individual.net:

bearing in mind that time is of the
essence.

Which is why simpling disabling a system that has already driven the
setting to the far extreme and requiring the already distracted pilot
to manually screw back the setting at one 4th the rate in a panic, is
100% unacceptable.

The simple alternative was to use the trim buttons to get the trim back
to near normal, and only then turn off the electric to the trim motors.
And these pilots had to know that their trim buttons were working, we
have the FDR data showing they used those buttons many times and it worked.
In the case of LA, they used them for close to ten minutes, before crashing.
At any point, with the trim near neutral, they could have shut off the
switches. And that didn't require knowing about MCAS or anything beyond
the very basics of flying and the systems on any similar aircraft.

If someone else's arm is on my stick to help. I wany him OFF as soon
as I say, not merely still attached and sluggish but no longer
physically fighting the pilot to right the plane.

I want his arm removed and immediate full control restored.

And I know it is physically possible.

Yes, we call that the mythical cutter offer, just for you.

Wrong, always wrong.

 

On Tuesday, May 7, 2019 at 9:13:40 AM UTC-4, DecadentLinux...@decadence.org wrote:

Sylvia Else <sylvia@email.invalid> wrote in
news:gjdbgdFo8vtU1@mid.individual.net:


The trim is a normal part of the aircraft's control system, and it
doesn't have a fixed correct position to which it could be
restored. It has to be adjusted frequently during the flight
depending on many factors.

You are confusing aircraft basic elements.

trim tabs are small portions of flight surfaces.

The MCAS system here moves the entire elevator on the plane.

Wrong again. Anyone who has followed this knows that MCAS only
works by using the trim. That is why Boeing put out the directive after
the first crash, LA, to use the RUNAWAY TRIM PROCEDURE if MCAS screwed
up again. And we know it works, the LA flight the previous day, the
jump seat pilot told the dummies flying to turn off the trim, they did,
they adjusted it manually, the plane flew on to it's destination.


Wrong, always wrong.

That is not a trim tab, and though the operation is technically
referred to as trim, in this case it is MAJOR TRIM, not some tiny in
flight adjustment made to optimze fuel consumption.

Thanks for further demonstrating that you're clueless about what trim
is even about.

So it is actually NOT 'normal', much less 'normal trim' at all.

One thing is for sure, you're not normal. Wrong, always wrong.

 

On Tuesday, May 7, 2019 at 10:40:37 AM UTC-4, Riley Angel wrote:

On 2019-05-07 03:56, Martin Brown wrote:
On 07/05/2019 05:17, Riley Angel wrote:
On 2019-05-06 06:46, trader4@optonline.net wrote:

The issue with the 737 Max is that at high levels of AOA, the plane has
a tendency to nose up even further.  Part of the certification process
is that if you release the controls the plane is supposed to head in
a stable direction, not toward instability.  That is why MCAS was added.

This is incorrect.

In what way is it incorrect? His description is a fairly succinct
explanation of the problem that MCAS was intended to address. Namely
that the physically bigger engines and shifted centre of gravity made
the plane tend towards an AoA stall condition if left to its own
devices. (but only in some fairly rare edge cases)


This is also incorrect

There are no CoG problems with 737 Max 8, or stability problems, or
anything else of that ilk which the press seem to be peddling with abandon.
It is true that it has larger engines whch are mounted further aft

That is wrong, the engines are mounted further forward.

and

higher, but the essential problem is that the nacelles are larger and
generate more lift, particularly at higher AoA. This compounds the
pitch/thrust moment that the 737 classic is also known for, which is a
tendency for the aircraft to generate higher AoA itself through thrust
rather than control surfaces, although who knows if the higher engine
mounting position actually ameliorates that by reducing the length of
the moment arm.

Which of course is what I described.

MCAS is described as a safety feature, but all it was intended to do is
ensure that at higher angles of attack, the elevator /feel/ does not
change to make less elevator input force (stick back) required at high
AoA. It is not designed to save the airframe in some way from bad
piloting, in the same way that the stick-shaker stall warning won't
cause thrust to be applied or nose-up command inputs to be made without
the pilot performing those actions.

This is a fundamental point; the Max 8 is a completely new aircraft

That isn't true. If it was, Boeing would have to go through a new
type certification, which was one key thing they wanted to avoid,
for obvious reasons. They wanted pilots that already have a rating
for the 737 to be able to fly it, no new rating required. They took
most of the existing 737 design and used that. One big change was
the need to go to the larger, more fuel efficient engines.



but

with similar enough flight controls to the preceding 737 that aviation
authorities, particularly the FAA, were willing to certify it as being
flyable by existing pilots without major type training, or as it turns
out, allow Boeing to self-certify large parts of a completely new design
to that end. That the controls simply perform the same way as pilots are
used to and are required by certain regulations was presumably a major
consideration in the instigation of MCAS in the first place.

And part of that is that without MCAS, the Max has a nasty tendency to
continue to pitch up on it's own, which near the stall limit, could
push it into a stall. It's not a good new feature, it's one that's
a problem.

It is simply unfortunate that some people got too far out of their box
and allowed the unit to have far more authority than it needed to
perform that function, and the design was a piece of crap with single
points of failure.

It's not clear that anyone went out of their box, unless you know what
exactly happened during the design and changes at Boeing.

 

On Tuesday, May 7, 2019 at 6:56:23 AM UTC-4, Martin Brown wrote:

On 07/05/2019 05:17, Riley Angel wrote:
On 2019-05-06 06:46, trader4@optonline.net wrote:

The issue with the 737 Max is that at high levels of AOA, the plane has
a tendency to nose up even further. Part of the certification process
is that if you release the controls the plane is supposed to head in
a stable direction, not toward instability. That is why MCAS was added.

This is incorrect.

In what way is it incorrect? His description is a fairly succinct
explanation of the problem that MCAS was intended to address.

Thank you. You shouldn't even have to ask him what he means.
One thing I've noted is that those that don't want to contribute, but
only want to stir up trouble, are the ones that post one or three
word replies, like "wrong", or "this is incorrect" and nothing more.

 

On Tuesday, May 7, 2019 at 9:19:39 AM UTC-4, DecadentLinux...@decadence.org wrote:

Sylvia Else <sylvia@email.invalid> wrote in
news:gjdbgdFo8vtU1@mid.individual.net:

and as
has been abundantly demonstrated, you don't want things messing
with the position of the tailplane.

Wake up! That is what MCAS does. It does not move a trim tab. It
moves the entire tailplane (elevator).

Wrong, always wrong.

 

On Tuesday, May 7, 2019 at 9:18:38 AM UTC-4, DecadentLinux...@decadence.org wrote:

Sylvia Else <sylvia@email.invalid> wrote in news:gjdbgdFo8vtU1
@mid.individual.net:

Anything more complicated just introduces other failure modes,

I said nothing about something more complicated.

Of course you did. You proposed another complication to intervene,
the cutter-offer.

Having motors turn jacks screws and then expecting pilots to crank
them back manually is ludicrous.

It's very reasonable and used widely in all kinds of aircraft, where in
an emergency you can hand crank, eg landing gear. And we know it worked,
the LA flight the day before the crash did it.

Hell if anything, they should have an "invert switch" on it, so the
pilot could throw that and the plane would reverse it's manipulation
and then flip it back and turn it off at the center point restoring
immediate and even assisted full control. TIME IS OF THE ESSENCE when
an automated control system malfucntions.

And above you deny that you introduced any new complications.

It should be hydraulic and releaseable. Not simply "hand resetable"
to your magic 'needs to be here to resume' location. Let it control,
and if it screws up, REMOVE it 100% from control with no manual dial
back requisite. Real simple. Not complex.

Do you have any relatives working at Boeing on the 737 Max program?

 

[Banders]

On 05/07/2019 05:57 AM, trader4@optonline.net wrote:

On Tuesday, May 7, 2019 at 12:33:45 AM UTC-4, Banders wrote:
On 05/06/2019 11:55 AM, trader4@optonline.net wrote:

Mushing has nothing to do with what I stated. Explain to us how a 737
that's been going 300 MPH in level flight for 30 seconds can be stalling.
It can't.

Not during those 30 seconds perhaps, but wind shear can change things in
an instant.

Again, explain to us how any wind shear on this planet, can cause a plane
that is in level flight, at 300 MPH, for the last 30 seconds to stall.

Does this link work?
<https://en.wikipedia.org/wiki/Supercell#/media/File:Supercell.svg>

You would be lucky to have the wings stall rather than be torn off.

 

On Tuesday, May 7, 2019 at 9:55:34 AM UTC-4, Martin Brown wrote:

On 07/05/2019 08:17, Jasen Betts wrote:
On 2019-05-07, Riley Angel <4736angel@pm.me> wrote:
On 2019-05-06 06:42, Jan Panteltje wrote:
I have read lately it was, it is anyways in the sense that it did not detect the output to ever tilt the thing more and more.
Looks like the dumbest loop you can ever write.
It did not check angular position (I think they added that now, only takes a 1$ MEMS chip),
and it had no redundancy.

They already had an artificial horizon. The thing that was missing was
any kind of sanity check on the validity of the AoA sensor output.

And just yesterday we learned that Boeing learned way back in 2017
that the AOA disagree light didn't work unless the plane had the
AOA display option. So there
was a warning light bulb that would not go on, unless that plane
had the AOA display option, which they were charging for. Boeing
planned to fix it in a software update, but that never happened
before the crashes. Previously it was said that they offered the
disagree light and the display as options. Putting this together,
it sounds like you could pay for the disagree light, but it didn't
actually work, unless you had the display option too.

There was also a major discrepancy between what Boeing told the FAA MCAS
would do in terms of how much adjustment and what it did in actuality.
This is unforgivable at multiple levels. No-one will ever trust the FAA
again outside of the USA. They were in bed with Boeing and prepared to
keep planes flying they knew to be dodgy even after the second crash.

It certainly looks like there was a cozy relationship. But on the other
hand, if Boeing didn't tell the FAA that they had increased the action
by 3X, IDK how FAA would know.

Finally Boeing have been forced to admit they knew about this problem
and the AoA vulnerability more than a year before the first crash but
had convinced themselves that it wasn't a safety critical problem.

https://www.bbc.co.uk/news/business-48174797

Have to be careful there about which problem you're talking about.
This is about the AOA disagree light not working in some planes,
which I talked about above. Not sure what level of urgency was
needed to fix that, given that many of the Max apparently don't have
the disagree light at all. I'd say they should have put out an alert
to operators though. Doesn't seem like that would have made a difference
in the crashes though, from what I saw. For one thing, pilots were
never told about MCAS, how it uses the AOA sensors, etc. Which raises
the question, on the planes that had the disagree light, what did
the pilots thing the AOA and this light all about? Many planes didn't
display AOA, so then what's up with the light and WTF were they supposed
to think that it was for?

Apparently they said "it did not jeopardise flight safety" which is true
in normal operation but completely untrue when the dodgy AoA sensor goes
haywire and MCAS puts the plane into an almost unrecoverable power dive.

If the pilots knew about MCAS and had a working disagree light, I wonder
what would have happened with the crash flights. LA taxied out with one
AOA showing 20 deg, so if it had the light and if the light worked,
what would they have done?

It is an example of the fix being far more dangerous than the original
problem that it was supposed to address.

+1

Swing a $1 MEMS chip round your head. Which angular position is which
now? An aircraft in flight is essentially a free body with only gravity
as a reference, which can be confused by any other sort of acceleration
force.

It's worse than that. An aircraft in flight does not have gravity as a
reference, what keeps you in your seat is the reaction to lift, and
lift is perpendicular to the wings, not the ground.

That said whilst the GPS system is working you also have some pretty
good independent numbers for ground speed and rate of climb that are
reliable and are referenced to an external reference frame. Airspeed
indicators have been known to cause crashes when they malfunction too
but they can also provide a sanity check against the risk of stalling.

I posed the challenge to the dissenters here to show us how a plane
that's been flying level for 30 secs at 300 MPH can suddenly be
stalling. Of course the more complex you make the software to decide
between normal and abnormal, the more failure that can induce. Seems
a far better solution is that if the two AOA disagree, then MCAS turns
itself off and notifies the pilots. Or put in a third one and vote.

I think there probably are flight configurations where you can pretty
much rule out stalling altogether. Notably when the nose is pointing
down and the plane is already gaining speed by losing height.

Since the problem only arises in normal flight mode I am surprised that
the SOP for zapping MCAS misbehaviour on take-off was not to extend
flaps again and increase engine thrust - then you get the benefit of
full servo control of all the flight surfaces and MCAS is disabled.

Well, that's a damn good point too. I said before that since the
trouble started just as the flaps came off, when the pilots couldn't
figure out what was going on, you'd think trying flaps again might
be a logical idea. But what you raise doesn't make Boeing look
very smart again. Because on takeoff, just after the flaps have
been retracted, it would sure be a hell of a lot easier to re-deploy
them to disable MCAS than to turn off the trim and try to wind it
back from nose down, with limited altitude. I wonder if Boeing
had made that the procedure, if the Ethiopian pilots would have
done it? Maybe not, I don't think there is any evidence anything
was said about MCAS. But I agree that telling pilots that using
flaps is an option would have been a good idea. I guess they at
least did tell the pilots that MCAS only works with no flaps,
so pilots might have picked it up that way.

I am sure that eventually the story will come out how this thing was
certified as "airworthy" despite having such very obvious flaws.

--
Regards,
Martin Brown

Yes, it will be interesting. And interesting to see if it winds up with
any criminal charges, which seems unlikely so far.

 

On Tuesday, May 7, 2019 at 3:05:18 PM UTC-4, Tom Gardner wrote:

On 07/05/19 19:40, trader4@optonline.net wrote:
I posed the challenge to the dissenters here to show us how a plane
that's been flying level for 30 secs at 300 MPH can suddenly be
stalling.

It would help if you had some experience flying aircraft.

In other words, the answer is that it can't be stalling
and you know it. If not, I'll reissue the challenge, explain to us
how a 737 that's been flying level for 30 secs can suddenly be
stalling......

You're like an incompetent mechanic or HVAC tech that thinks only
they can understand anything about fixing cars or HVAC systems.
They get all pissed off when they find out that there are bright
people who know the facts, can sort out truth from BS and actually
fix their own cars and HVAC. And then they get sore, real sore.
You're sore too because I put part of the blame for the accidents
on the pilots, who could not identify runaway trim and follow the
procedure. That's a fact.