737 Max 8 Simulators

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Re: 737 Max 8 Simulators

Post by twinpratts »

Gino Under wrote: Mon Mar 25, 2019 5:42 pm You don’t know what your talking about.
:lol:
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Re: 737 Max 8 Simulators

Post by L39Guy »

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.
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Re: 737 Max 8 Simulators

Post by Oscar »

Does anyone have a link to the video of the Asian F/O stomping his foot on the "runaway" 737 trim wheel? It's like 20 seconds long, supposed to be sarcasm for the new MCAS recovery method. Someone showed it to me but I can't find it online. Funny stuff!
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Re: 737 Max 8 Simulators

Post by Dash.Trash »

Oscar wrote: Wed Apr 10, 2019 5:29 pm Does anyone have a link to the video of the Asian F/O stomping his foot on the "runaway" 737 trim wheel? It's like 20 seconds long, supposed to be sarcasm for the new MCAS recovery method. Someone showed it to me but I can't find it online. Funny stuff!
https://www.instagram.com/p/BvXFnTxlW15 ... ko46w4sb0p
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Re: 737 Max 8 Simulators

Post by confusedalot »

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
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Re: 737 Max 8 Simulators

Post by Yycjetdriver »

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 »

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 »

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 »

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 »

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 »

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 »

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 »

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 »

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 3759 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 »

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

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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 »

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 »

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 »

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 »

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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