737 Max 8 Simulators

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Yycjetdriver
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Re: 737 Max 8 Simulators

Post by Yycjetdriver » Tue May 07, 2019 7:45 pm

confusedalot wrote:
Tue Mar 26, 2019 6:17 pm
Do you, or do you not, have sim evaluation time?






.
What’s sim evaluation time?
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Re: 737 Max 8 Simulators

Post by sepia » Mon May 13, 2019 4:50 pm

confusedalot wrote:
Tue May 07, 2019 6:01 pm
L39Guy wrote:
Wed Apr 10, 2019 5:22 pm
Confusedalot,

How would an MCAS failure look differently in a simulator compared to a stab trim runaway? What are the differences in the emergency drill?

Answer: there is no difference.
Just stumbled on this......

You are 100% right, hit the switches and everything gets disabled. One caveat, never flew the max, just did simulator stuff, but from what I know, you disable everything

It's old news now, the real problem is that Boeing did not tell anybody about the mcas.
Hell, even I did not know about it. You would figure that a sim evaluator would be provided with the information.

How is a sim evaluator supposed to do his job without information,?

How is a line pilot supposed to save the day with no knowledge?

Sad situation indeed
Answer: There definitely are differences. Here’s a few off the top of my head.

MCAS runaway runs at the flaps down trim speed. MCAS only operates with flaps up, so it’s trimming down a much quicker rate than you’re trimming back at.

A stab trim runaway is coded in the Boeing binary as an electrical ground causing the trim to run continuously in the direction in which trim is applied first when the trim activates. Trimming in the opposite direction will stop the runaway, but will not trim counter to the runaway. So there’s no point in waiting to cutout the trim.

MCAS runaway can be stopped with yoke trim and it’s input can be reversed. It’s reversed at a lower speed as mentioned in point 1. So ideally you’d trim back to neutral before cutting out the trim with the drill.

Before someone wants to go nuts on the keyboard and tell me how wrong I am. Boeing made a multi hour presentation about this to a group I was a part of this month regarding the MAX. So unless somehow you’ve got better info than Boeing test pilots have, I’d save your keystrokes.
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Re: 737 Max 8 Simulators

Post by J31 » Mon May 13, 2019 7:12 pm

sepia wrote:
Mon May 13, 2019 4:50 pm


Answer: There definitely are differences. Here’s a few off the top of my head.

MCAS runaway runs at the flaps down trim speed. MCAS only operates with flaps up, so it’s trimming down a much quicker rate than you’re trimming back at.

A stab trim runaway is coded in the Boeing binary as an electrical ground causing the trim to run continuously in the direction in which trim is applied first when the trim activates. Trimming in the opposite direction will stop the runaway, but will not trim counter to the runaway. So there’s no point in waiting to cutout the trim.

MCAS runaway can be stopped with yoke trim and it’s input can be reversed. It’s reversed at a lower speed as mentioned in point 1. So ideally you’d trim back to neutral before cutting out the trim with the drill.

Before someone wants to go nuts on the keyboard and tell me how wrong I am. Boeing made a multi hour presentation about this to a group I was a part of this month regarding the MAX. So unless somehow you’ve got better info than Boeing test pilots have, I’d save your keystrokes.
Finally someone who knows and understands what the MAX is capable off.

I have flown a few aircraft with quirks but never one that could repeatably try to kill you.
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Re: 737 Max 8 Simulators

Post by L39Guy » Mon May 13, 2019 8:21 pm

According to a recent article in Aviation Week, ALPA will not be insisting on specialized MCAS simulator training. In addition to this, Southwest won't be doing any specific training either as "Managing the aircraft in a runaway stabilizer scenario is something that we already trained on and…has already been covered".

(https://aviationweek.com/commercial-avi ... 75c823d4de)
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Re: 737 Max 8 Simulators

Post by goingnowherefast » Tue May 14, 2019 5:08 am

Being aware of a failure mode, associated symptoms and to action a previously trained procedure is a lot different than not knowing the system even exists.
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Re: 737 Max 8 Simulators

Post by Daniel Cooper » Tue May 14, 2019 10:46 am

L39Guy wrote:
Mon May 13, 2019 8:21 pm
ALPA will not be insisting on specialized MCAS simulator training.
I'm surprised to hear that. I thought ALPA may even insist on some kind of master disconnect switch for the MCAS system. Something that would still allow normal use of the trim and autopilot but just no MCAS. Weren't ALPA responsible for the crash bar style autopilot disconnect switch on Boeings? Many people thought it was being overly cautious and paranoid about automation. But sometimes it's good for pilots to stand up to the engineers.
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Re: 737 Max 8 Simulators

Post by L39Guy » Tue May 14, 2019 3:12 pm

There is nothing stopping the use of the autopilot. In fact, it shuts MCAS off. Using the electric trim switches on the control column turns MCAS off too while in manual flight.

I think the idea is to keep things simple by having the same procedure for an MCAS event as a stab trim runaway, which MCAS is by definition - an uncommanded trim input to the stabilizer. An stab trim runaway or an MCAS event is not time to be diagnosing which is which; a common procedure for both makes the most sense.
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Re: 737 Max 8 Simulators

Post by sepia » Tue May 14, 2019 5:20 pm

L39Guy wrote:
Tue May 14, 2019 3:12 pm
There is nothing stopping the use of the autopilot. In fact, it shuts MCAS off. Using the electric trim switches on the control column turns MCAS off too while in manual flight.

I think the idea is to keep things simple by having the same procedure for an MCAS event as a stab trim runaway, which MCAS is by definition - an uncommanded trim input to the stabilizer. An stab trim runaway or an MCAS event is not time to be diagnosing which is which; a common procedure for both makes the most sense.
To be blunt, everything you said was wrong. Literally everything.

Step 2 of the runaway stabilizer drill states verbatim "do not re-engage the autopilot"

Using the electric trim doesn't turn MCAS off. Electric trim uses a higher trim priority and will override MCAS temporarily. The moment you stop trimming, if the MCAS engagement criteria still exist, MCAS will recommence trimming at the flaps down trim speed, where you were trimming with flaps up speed. You specified manual flight, the entire speed trim system, of which MCAS works within, can only work in manual flight. So it's not like there's an auto flight possibility for this to happen.

MCAS isn't uncommanded stabilizer trim by definition. You should never ever have a 737 into a nose up attitude anywhere near the MCAS engagement criteria. If you did, MCAS provides pitch stability. If you believe this is uncommanded trim, then by your definition the entire speed trim system is uncommanded, and thus should be cut out. You'd be unlikely to fly many legs with the trim cutout if that were the case.

MCAS isn't being removed in the 12.1.1 updates. It's simply having disengagement criteria added. You'll read all about them before the planes return to the line.

Sorry for coming in so hot there, but you've got some very fundimental lack or knowledge about MCAS and the speed trim system.
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Re: 737 Max 8 Simulators

Post by L39Guy » Wed May 15, 2019 6:28 am

sepia wrote:
Tue May 14, 2019 5:20 pm
L39Guy wrote:
Tue May 14, 2019 3:12 pm
There is nothing stopping the use of the autopilot. In fact, it shuts MCAS off. Using the electric trim switches on the control column turns MCAS off too while in manual flight.

I think the idea is to keep things simple by having the same procedure for an MCAS event as a stab trim runaway, which MCAS is by definition - an uncommanded trim input to the stabilizer. An stab trim runaway or an MCAS event is not time to be diagnosing which is which; a common procedure for both makes the most sense.
To be blunt, everything you said was wrong. Literally everything.

Step 2 of the runaway stabilizer drill states verbatim "do not re-engage the autopilot"

Using the electric trim doesn't turn MCAS off. Electric trim uses a higher trim priority and will override MCAS temporarily. The moment you stop trimming, if the MCAS engagement criteria still exist, MCAS will recommence trimming at the flaps down trim speed, where you were trimming with flaps up speed. You specified manual flight, the entire speed trim system, of which MCAS works within, can only work in manual flight. So it's not like there's an auto flight possibility for this to happen.

MCAS isn't uncommanded stabilizer trim by definition. You should never ever have a 737 into a nose up attitude anywhere near the MCAS engagement criteria. If you did, MCAS provides pitch stability. If you believe this is uncommanded trim, then by your definition the entire speed trim system is uncommanded, and thus should be cut out. You'd be unlikely to fly many legs with the trim cutout if that were the case.

MCAS isn't being removed in the 12.1.1 updates. It's simply having disengagement criteria added. You'll read all about them before the planes return to the line.

Sorry for coming in so hot there, but you've got some very fundimental lack or knowledge about MCAS and the speed trim system.
Whoa, cowboy, just take it easy. I think you are misinterpreting my responses to the comments made by Daniel Cooper.

It is true, is it not, that MCAS is not active when the autopilot is on? That is one of the operating principles of the system. It is also true that MCAS is not active when the flaps are extended? The answer to both of these questions is clearly yes, that MCAS is silent in automatic flight and with the flaps extended.

I did not say that engaging the autopilot was part of the stab trim runaway recovery, that was not the question. The stab trim runaway checklist is provided as follows:
Stab Trim Runaway.jpg
Stab Trim Runaway.jpg (167.7 KiB) Viewed 2290 times
.

And it is equally true that the use of the manual trimming switches on the control column nullify MCAS - or more specifically the nose down trimming action - while they are used. Perhaps my choice of words should have been better but the intent is that manually trimming overrides the MCAS caused nose down trimming action.

MCAS, to the pilot, is indeed an uncommanded stabilizer trim movement. Have another look at the Runaway Stabilizer NNC I provided: "Condition: Uncommanded stabilizer trim movement occurs continuously". With MCAS in action:
- is there trim movement. Yes.
- Is it uncommanded (i.e. not selected by the pilot). Yes.
- Does it occur continuously. Yes (10 seconds at at time)

MCAS satisfies all three conditions of Runaway Stabilizer.

I agree with the raison d'etre of MCAS, which is providing positive pitch stability at high angles of attack which is not naturally present owing to the placement of the engines. And I agree that one should never get to that area of the envelope but there are idiots who might and that's why the FAR's are written to provide positive stability to get the nose down and MCAS is the vehicle to do that.

Is the Speed Trim System (STS) a runaway trim - no, as it fails to meet the definitions as it does not occur continuously but rather intermittently. Moreover, it is a normal operation of the trim; MCAS is not, particularly when it fails as we have seen in these accidents where the angle of attack is nowhere near high.

MCAS not being removed is not surprising as the certification requirement that necessitated it in the first place (positive stability throughout the entire flight regime including high alpha) has not changed.

According to ALPA in that article and Southwest (and others), they consider an MCAS event a Stab Trim Runaway event which demanded the use of the procedure provided here. This was also stated by the FAA administrator, who is an experienced airline pilot. I think everyone else in the industry understands what a stab trim runaway looks like, regardless of its cause such as MCAS, a stuck trim switch, a short circuit in the wiring, etc. The cause is irrelevant while in flight.

BTW, I have 16 years on the B737 so I have a pretty good understanding of its operation plus another 5 on the 767/777/787 which all have similar stab trim runaway procedures except the back-up trim is electric not the hand crank.
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Re: 737 Max 8 Simulators

Post by sepia » Wed May 15, 2019 10:21 am

The QRH page you posted isn't current and hasn't been since the fall.

If you believe MCAS is uncommanded trim and thus should be cut out anytime it runs how will it remain certified?

I think I'm done here. Enjoy the bigger Boeing's.
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Re: 737 Max 8 Simulators

Post by L39Guy » Wed May 15, 2019 11:47 am

Well, let's see...you're manually flying along fat, dumb and happy (and in trim) and suddenly the nose lurches down and the windshield is nothing but the planet earth, the control wheel gets really heavy and the stab trim wheel is spinning. I would call that "uncommanded trim" - what would you call it? Normal?
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Re: 737 Max 8 Simulators

Post by complexintentions » Tue May 21, 2019 6:10 am

sepia wrote:
Wed May 15, 2019 10:21 am
The QRH page you posted isn't current and hasn't been since the fall.

If you believe MCAS is uncommanded trim and thus should be cut out anytime it runs how will it remain certified?

I think I'm done here. Enjoy the bigger Boeing's.
How has the new QRH page/procedure changed? Or are you just being pedantic and missing the point being (I might add, very well) made by L39?

You're deliberately being obtuse. Of course the normal operation of MCAS is not considered uncommanded trim - trimming is the design purpose of the system. But when it trims inappropriately, just like when any aircraft system operates in a way that places the flight in jeopardy, it's the pilots job to apply the correct procedure to resolve it.

There is a longstanding procedure to deal with the symptoms of the failure and they weren't followed. If you want to nitpick about the wording of it, go ahead.
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Re: 737 Max 8 Simulators

Post by Gilles Hudicourt » Tue May 21, 2019 7:24 am

L39Guy wrote:
Wed Apr 10, 2019 5:22 pm
Confusedalot,

How would an MCAS failure look differently in a simulator compared to a stab trim runaway? What are the differences in the emergency drill?

Answer: there is no difference.
That is false.

1) The Standard Runaway trim fault does not have a stall warning and stick shaker associated with it.
2) The Standard Runaway trim fault is not associated with an IAS Disagree alert, which when it happens at take off, calls for the pilot to disconnect autopilot and auto thrust and maintain 10 degree nose up and 80% N1 (The MCAS fault kicks in at flaps up after the Stall warning and the IAS Disagree)
3) The Standard Runaway trim fault does not stop when you input some electric trim, pause a number of seconds, and -re-activate again, and so forth in a loop.

I read somewhere that the Ethiopian PIC had selected 235 in the speed window at some point, and then never touched the throttles after that, thinking the speed and power issue had been taken care of, when in fact the aircraft was at high power setting until impact. Had he previously disconnected the auto thrust as part of the Unreliable airspeed drill but forgot about it ?
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Re: 737 Max 8 Simulators

Post by complexintentions » Tue May 21, 2019 8:08 am

Gilles Hudicourt wrote:
Tue May 21, 2019 7:24 am
L39Guy wrote:
Wed Apr 10, 2019 5:22 pm
Confusedalot,

How would an MCAS failure look differently in a simulator compared to a stab trim runaway? What are the differences in the emergency drill?

Answer: there is no difference.
That is false.

1) The Standard Runaway trim fault does not have a stall warning and stick shaker associated with it.
2) The Standard Runaway trim fault is not associated with an IAS Disagree alert, which when it happens at take off, calls for the pilot to disconnect autopilot and auto thrust and maintain 10 degree nose up and 80% N1 (The MCAS fault kicks in at flaps up after the Stall warning and the IAS Disagree)
3) The Standard Runaway trim fault does not stop when you input some electric trim, pause a number of seconds, and -re-activate again, and so forth in a loop.

I read somewhere that the Ethiopian PIC had selected 235 in the speed window at some point, and then never touched the throttles after that, thinking the speed and power issue had been taken care of, when in fact the aircraft was at high power setting until impact. Had he previously disconnected the auto thrust as part of the Unreliable airspeed drill but forgot about it ?

But there ARE procedures to deal with Unreliable Airspeed (or whichever term the B737 uses) and stall warning/stick shaker, are there not? Neither of which include repeatedly attempting to engage the autopilot.

Your point that there were multiple confusing indications simultaneously is taken, but that doesn't change that the actual undesired trim condition most certainly should have been handled no differently than an uncommanded trim caused by any other factor. Even MCAS doesn't work when you cut the power to it.

In the end some critical thinking HAS to be applied, not just blind adherence to procedure. The false stall warning and airspeed indications would be more credible as factors if it hadn't been daylight VMC...
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Re: 737 Max 8 Simulators

Post by Gilles Hudicourt » Tue May 21, 2019 10:31 am

When I was a 757 driver, I remember downloading and studying an accident report from an Aeroperu 757. I went through the FCOM to understand everything that happened.....

https://www.skybrary.aero/bookshelf/books/1719.pdf (This is an unofficial translation of the official accident report in Spanish)
The guys had taken off in Night VMC condition with scotch tape on all their Static ports. They crashed after 29 minutes and everyone died.
It should have been a standard Unreliable airspeed exercise, and the pilots could be accused of incompetence until you study the details (the captain had upwards of 20,000 hours) They were bombarded with so many and often contradictory bells, lights, EICAS messages, aural warnings that they eventually lost it and crashed. They no longer knew which warnings were valid and which had to be ignored. In the end, they trusted some that should have been ignored and ignored some that should have been trusted.
Their altimeters, airspeeds and VSIs were not working properly. But in addition to that, they had Wind Shear alarm, Rudder Ratio and Mach Speed Trim warnings, over speed warning, stick shaker and stall warning, Too Low Terrain, Sink Rate and maybe others that I missed. It was warning overload.

Yet all they had was an Unreliable Airspeed fault. Nothing else. It’s so easy to judge them and say that had they recognized it and dealt with it as per the QRH, they would have made it.

The 737-8 accident crews had similar experiences.....
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Re: 737 Max 8 Simulators

Post by complexintentions » Tue May 21, 2019 3:42 pm

Gilles Hudicourt wrote:
Tue May 21, 2019 10:31 am
The guys had taken off in Night VMC condition with scotch tape on all their Static ports.

The 737-8 accident crews had similar experiences.....


No. It was daylight VMC with the Ethiopian accident. Even with a delay to account for startle effect, an unreliable airspeed/ spurious stall warning should have been quite readily identified as false with visual reference, unlike the example you quote. Surely we can agree that things are a lot easier when you can see good old terra firma.

As your own account details, the Aeroperu had far more to deal with, given that their entire pitot/static system was compromised.I am not discounting the impact of multiple contradictory indications, only that the two situations are not comparable in scope.

I would suggest that in both situations, if you are completely overwhelmed go back to basics and fly pitch, power and attitude. Essentially, the Unreliable Airspeed memory items. Neither crew did this. 340 knots?!

Sometimes trying to do it "by the book" creates its own problems.
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Re: 737 Max 8 Simulators

Post by L39Guy » Wed May 22, 2019 12:08 am

Gilles Hudicourt wrote:
Tue May 21, 2019 7:24 am
L39Guy wrote:
Wed Apr 10, 2019 5:22 pm
Confusedalot,

How would an MCAS failure look differently in a simulator compared to a stab trim runaway? What are the differences in the emergency drill?

Answer: there is no difference.
That is false.

1) The Standard Runaway trim fault does not have a stall warning and stick shaker associated with it.
2) The Standard Runaway trim fault is not associated with an IAS Disagree alert, which when it happens at take off, calls for the pilot to disconnect autopilot and auto thrust and maintain 10 degree nose up and 80% N1 (The MCAS fault kicks in at flaps up after the Stall warning and the IAS Disagree)
3) The Standard Runaway trim fault does not stop when you input some electric trim, pause a number of seconds, and -re-activate again, and so forth in a loop.

I read somewhere that the Ethiopian PIC had selected 235 in the speed window at some point, and then never touched the throttles after that, thinking the speed and power issue had been taken care of, when in fact the aircraft was at high power setting until impact. Had he previously disconnected the auto thrust as part of the Unreliable airspeed drill but forgot about it ?
I beg to differ. The UAS (stick shaker and IAS disagree) was present from the moment the aircraft lifted off, about two minutes before the flaps were raised and MCAS kicked. They had two minutes to do this drill in isolation and didn’t. It is important to note that the Lion Air incident crew did do the drill and both accident flights did not. How do you explain the UAS NNC NOT being performed in the first two minutes of these flights?

If UAS and MCAS occurred simultaneously you would have a valid point, they did not.

The SW B737 crew that dealt with the engine explosion and rapid depressurization had simultaneous failures, the MCAS aircraft did not.

What is a standard runaway trim emergency? A runaway trim is anytime uncommanded trim is being applied, continuous, intermittent, or whatever. This is common to to virtually all aircraft. The duration, source, cause and minutia of its characteristics is irrelevant in flight. But to your point, how about a trim failure caused by loose wire shorting out intermittently? Would you treat that as a runaway and shut the system off, per the Stab Trim Runaway or would you continue as it doesn’t meet the “standard” trim runaway. I know what I would do.
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Re: 737 Max 8 Simulators

Post by L39Guy » Wed May 22, 2019 12:13 am

Gilles Hudicourt wrote:
Tue May 21, 2019 10:31 am
When I was a 757 driver, I remember downloading and studying an accident report from an Aeroperu 757. I went through the FCOM to understand everything that happened.....

https://www.skybrary.aero/bookshelf/books/1719.pdf (This is an unofficial translation of the official accident report in Spanish)
The guys had taken off in Night VMC condition with scotch tape on all their Static ports. They crashed after 29 minutes and everyone died.
It should have been a standard Unreliable airspeed exercise, and the pilots could be accused of incompetence until you study the details (the captain had upwards of 20,000 hours) They were bombarded with so many and often contradictory bells, lights, EICAS messages, aural warnings that they eventually lost it and crashed. They no longer knew which warnings were valid and which had to be ignored. In the end, they trusted some that should have been ignored and ignored some that should have been trusted.
Their altimeters, airspeeds and VSIs were not working properly. But in addition to that, they had Wind Shear alarm, Rudder Ratio and Mach Speed Trim warnings, over speed warning, stick shaker and stall warning, Too Low Terrain, Sink Rate and maybe others that I missed. It was warning overload.

Yet all they had was an Unreliable Airspeed fault. Nothing else. It’s so easy to judge them and say that had they recognized it and dealt with it as per the QRH, they would have made it.

The 737-8 accident crews had similar experiences.....
The big difference between Aeroperu and the MAX situation is that there was no UAS drill prior to Aeroperu but there is one for the MAX. A UAS drill was one of the lessons learned from Aeroperu.
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Re: 737 Max 8 Simulators

Post by Gilles Hudicourt » Sun May 26, 2019 7:19 am

L39Guy wrote:
Wed May 22, 2019 12:13 am
The big difference between Aeroperu and the MAX situation is that there was no UAS drill prior to Aeroperu but there is one for the MAX. A UAS drill was one of the lessons learned from Aeroperu.
You brought up a very interesting point. It took 70 years of commercial flying before Boeing decided that an UAS drill was required ?
What made that change necessary ?

In basic aircraft design, an aircraft instrument panel is made to be redundant and there is always a backup system that allows you to survive in case of loss of any one system. A basic Cessna 172's panel has :
The magnetic compass (self contained)
An Airspeed Indicator (pitot tube and static port)
A Vertical Speed Indicator (static port)
A Directional gyro (Vacuum pump)
An Artificial Horizon (Vacuum Pump)
A Turn and Bank Indicator or a Turn Coordinator (Electrical)
A Stall warning (self contained)

The loss of either the Vaccum Pump, the electrical system, the pitot tube or the the static port will still leave enough instruments working to keep control of the aircraft. Pilots are taught very early to not only know what system powers what instrument but also to know which instruments they can trust and which they must remove from their scan once the failed system has been identified.

This was still true in early transport Category aircraft, even when the systems got more complex. The electrical systems for example became more complex and buses were introduced with electrical back ups. Some instruments needed an inverter to work on AC, while others were DC. Still pilots were taught which was which and knew exactly what instruments failed when a generator or an inverter was lost, and which ones remained operational.

This segregation was however lost at a certain stage of aircraft design. Today, in glass cockpits, all instruments are electrical, so a total loss of electricity would spell disaster. The electrical system became complex, so the failure of one instrument powered by one bus would not knock out the whole system. There are AC and DC buses, main buses, emergency buses, battery buses, bus ties etc.

But we still have as instrument sources the classic pitot tubes, static ports and AOA vanes. There are also new input sources such as IRS And GPS. When today's pilot looks at his instrument panel, can he really know with certainty which will work and which will not in the advent of the loss of a particular system ?

On the 737 NG, the loss of of the AOA probe affects the Indicated airspeed. Huh ?
In the Airbus 330, the VSI is hybrid Static-Port and IRS. Huh ?
In the Airbus 330, in case of unreliable airspeed, we are told to always trust the stall warning indication which is independent of the Pitot Static (like in most aircraft).
In the Boeing 737NG, we are told on the contrary NOT to trust the stall or over-speed warnings in case of and unreliable airspeed.

Now, because of the complexity of the aircraft systems and the way they are programmed into the aircraft software, we have failures of some systems which cause erroneous indications of other systems that at first impression are totally foreign to the failed system.

The AeroPeru 757 had one problem and one problem only. Clear scotch tape had been applied to all its static ports by those who had been tasked with cleaning the aircraft had installed to avoid spaying water in them after they had been asked to wash the aircraft and warned not to spray water in the static ports. They forgot to remove the tape, and the flight crew who did the walk around at night, failed to see the clear scotch tape over all the static ports.

What should have been a clear case of a pitot-static problem had this jet been an older 737 or DC-8, turned into a nightmare for the 20,000 hour captain because of the conflicting and multiple unrelated warnings he experienced after take off.

Airspeed Indication Problem
VSI indication problem
Wind shear warning
Stall Warning
Overspeed warning
Rudder Ratio Warning
MAch TRim Warning
GPWS warnings......

This is what happened to AeroPeru
This is what happened to Air France 447

I don't blame the 737 MAX pilots one bit for their failure to save the aircraft.
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Last edited by Gilles Hudicourt on Wed May 29, 2019 8:47 am, edited 8 times in total.

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Re: 737 Max 8 Simulators

Post by dumbbell daddy » Sun May 26, 2019 12:04 pm

Gilles Hudicourt wrote:
Sun May 26, 2019 7:19 am
L39Guy wrote:
Wed May 22, 2019 12:13 am
The big difference between Aeroperu and the MAX situation is that there was no UAS drill prior to Aeroperu but there is one for the MAX. A UAS drill was one of the lessons learned from Aeroperu.
You brought up a very interesting point. It took 70 years of commercial flying before Boeing decided that an UAS drill was required ?
What made that change necessary ?

In basic aircraft design, an aircraft instrument panel is made to be redundant and there is always a backup system that allows you to survive in case of loss of one system. A basic Cessna 172"s panel has :
The magnetic compass (self contained)
An Airspeed Indicator (pilot tube and static port)
A Vertical Speed Indicator (static port)
A Directional gyro (Vacuum pump)
An Artificial Horizon (Vacuum Pump
A Turn and Bank Indicator or a Turn Coordinator (Electrical)
A Stall warning (self contained)

The loss of either the Vaccum Pump, the electrical system, the pitot tube or the the static port will still leave enough instruments to keep control of the aircraft. Pilots are taught very early to not only know what system powers what instrument but also to know which instruments they can trust and which they must remove from their scan once the failed system has been identified.

This was still true in early transport Category aircraft, even when the systems got more complex. The electrical systems became more complex and buses were introduced with electrical back ups. Some instruments needed an inverter to work on AC, while others were DC. Still pilots were taught which was which and knew exactly what instruments failed when a generator or an inverter was lost, and which ones remained operational.

This segregation was lost at a certain stage of aircraft design. Today, for one thing, all instruments are electrical, so a total loss of electricity would spell disaster. So the electrical system became complex, so the failure of one system powered by one bus would not knock out the whole system. There are AC and DC buses, main buses, emergency buses, battery buses etc.

But we still have the classic pitot tubes, static ports and AOA vanes. There are new input sources such as IRS And GPS. When today's pilot looks at his instrument panel, can he really know which will work and which will not in the advent of the loss of a particular system ?

On the 737 NG, the loss of of the AOA probe affects the Indicated airspeed. Huh ?
In the Airbus 330, the VSI is hybrid pitot-Static and IRS. Huh ?
In the Airbus 330, in case of unreliable airspeed, where are told to always trust the stall warning indication which is independent of the Pitot Static (like in most aircraft).
In the Boeing 737NG, we are told on teh contrary not to trust the stall or overspeed warning in case of and unreliable airspeed.

Now, because of the complexity of the aircraft systems and the way they are programmed into the aircraft software, we have failures of some systems which cause erroneous indications of other systems that are totally foreign.

The AeroPeru 757 had one problem and one problem only. There was clear scotch tape on all its static ports, that those who had been tasked with cleaning the aircraft had installed to avoid spaying water in them after they had been asked to wash the aircraft and warned not to spray water in the static ports. They forgot to remove the tape, and the flight crew who did the walk around at night, failed to see the clear scotch tape over all the static ports.

What should have been a clear case of a pitot-static problem had this jet been an older 737 or DC-8, turned into a nightmare for the 20,000 hour pilot because of the conflicting and multiple unrelated warnings this 757 crew received after take off.

Airspeed Indication Problem
VSI indication problem
Wind shear warning
Stall Warning
Overspeed warning
Rudder Ratio Warning
MAch TRim Warning
GPWS warnings......

This is what happened to AeroPeru
This is what happened to Air France 447

I don't blame the 737 MAX pilots one bit for their failure to save the aircraft.
100% agree with every word Gilles!
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L39Guy
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Re: 737 Max 8 Simulators

Post by L39Guy » Mon May 27, 2019 6:11 pm

Gilles,

Excellent dissertation.

I would add, if I recall my A330 days correctly, an inter relationship between the aircraft clock and the flap motors, or something like that.

Regardless of the inter relationships and complexity, it still boils down to the pilot to deal with anticipated and unanticipated failures such as double engine failures (USAir), engine failure/rapid decompression (SW), etc. In the MAX case, it was a stick shaker(implying a stall) with other things such as IAS Disagree. With three independent airspeed sources combined with the feel of an aircraft, a pilot should be able to sort out whether the aircraft is stalling or not (mushy feel to the flight controls) or whether the airspeed is unreliable and which one by comparing the three airspeed indicators.

But even if you can't determine what airspeed indicator is erroneous, Boeing provides a checklist that gives you a pitch and power combination that will guarantee that you will continue flying (with flaps extended 10 degrees pitch/85% power). That is exactly what the Lion Air incident crew did and in the process they were able to control the speed of the aircraft, were able to manually trim the aircraft and fly the aircraft for an hour and a half with unreliable airspeed and manual trim. The Lion Air crew the next day were presented with the same circumstance and did not do the UAS drill, which in designed precisely for this kind of event, regardless of how complex the aircraft systems may be.

Five months later, with the benefit of the Airworthiness Directive providing even more details of the MCAS issue including the unreliable airspeed, the crew did not even to the UAS drill, didn't control the speed of the aircraft, were unable to trim the aircraft manually while flying around at 340+ Kts.

Complex aircraft systems or not, at the end of the day, one still has to fly the airplane even if means going back to basics.
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Re: 737 Max 8 Simulators

Post by complexintentions » Tue May 28, 2019 2:50 am

No one is trying to "blame" anyone, not in the finger-pointing sense. But to suggest that the crews of any of the accident flights mentioned do not bear a measure of responsibility is foolhardy. MCAS did not cause the crew to reach 340 kts. The AF FO pulling full aft sidestick for minutes at a time was not caused by the pitot-static system freezing up. This is simply a concrete application of the "it's not who's right, but what's right" philosophy. It is not a personal attack on the pilots. We are only human and no one wants to see a colleague lose their life.

The point has been well-made and no one is arguing against the fact that the complexities of modern aircraft design have introduced new challenges for flight crew. But a dissertation on the differences of 70 years ago and now is not particularly helpful. I'm quite confident we're not going back to Cessna 172 level of simplicity machines just to accommodate the lowest common denominator of pilot knowledge and abilities.

Achieving the safe outcome of a flight is a joint responsibility of all involved parties, which in the case of MCAS the Boeing engineers failed miserably to fulfill their role of designing a properly fault-tolerant system. But I respectfully reject the implication that this absolves flight crews from our responsibility to be the last line of defence and not "to blame one bit".

Too much faith in engineering, too much reliance on tech. Why have we forgotten that the actual physics of flight have never changed?
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L39Guy
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Re: 737 Max 8 Simulators

Post by L39Guy » Tue May 28, 2019 7:57 pm

This article from a trade magazine, rather than a newspaper, nicely describes the issue.

https://m.aviationweek.com/business-avi ... eb43628438
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Re: 737 Max 8 Simulators

Post by Gilles Hudicourt » Fri May 31, 2019 6:57 am

L39Guy wrote:
Mon May 27, 2019 6:11 pm

I would add, if I recall my A330 days correctly, an inter relationship between the aircraft clock and the flap motors, or something like that.
Quite true. Between the aircraft clock and the wingtip brakes, a device meant to prevent asymmetrical flaps or slats. If during preflight, while setting the aircraft clock, the pilot inadvertently advances the date by 24 hours, the wingtip brakes activate, and maintenance has to be called to unlock them.


L39Guy wrote:
Mon May 27, 2019 6:11 pm
But even if you can't determine what airspeed indicator is erroneous, Boeing provides a checklist that gives you a pitch and power combination that will guarantee that you will continue flying (with flaps extended 10 degrees pitch/85% power). That is exactly what the Lion Air incident crew did and in the process they were able to control the speed of the aircraft, were able to manually trim the aircraft and fly the aircraft for an hour and a half with unreliable airspeed and manual trim. The Lion Air crew the next day were presented with the same circumstance and did not do the UAS drill, which in designed precisely for this kind of event, regardless of how complex the aircraft systems may be.
The Lion Air crew you mention, the one that survived, had a third pilot on the jumpseat who did not have his hands full and who called what he saw to the flying crew.

I can no longer find the source, but I read somewhere that the Ethiopian pilot selected 235 kts in the Speed Window at one point, so thought he had taken care of the speed and power problem. The aircraft remained at Take Off Power while the Speed Window had been selected at 235. After that, he needed both hands to keep the aircraft from plowing into the ground, and did not have a third hand to control the throttles. Just before the impact, he even asked his colleague to help him pull back on the yoke, but they were overpowered by the movable horizontal stabilizer.
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Re: 737 Max 8 Simulators

Post by Gilles Hudicourt » Fri May 31, 2019 7:02 am

L39Guy wrote:
Tue May 28, 2019 7:57 pm
This article from a trade magazine, rather than a newspaper, nicely describes the issue.

https://m.aviationweek.com/business-avi ... eb43628438
Very good article, except the author seems to be a bit geographically challenged. He first talks of the "Indonesian" and "African" flights, then refers to the Ethiopian aircraft as the "North African" aircraft.
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