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737 MAX - Safe or Unsafe?

Old 03-15-2019, 09:47 AM
  #71  
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Originally Posted by AirBear View Post
Whats happening to the SWA Max Pilots? Are they getting a paid vacation? Or can they just step back down to flying the standard 737-800?
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Old 03-15-2019, 10:58 AM
  #72  
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We don’t understand the system well enough collectively, and that’s part of the problem
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Old 03-15-2019, 11:47 AM
  #73  
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Originally Posted by barabek View Post
I think that a lot of the Monday morning quarterbacks here should wait for the final results of both investigations before judging the pilots' skills. How easy to criticize those who can't defend themselves. Try also imagining the situation at low altitude when your airplane is aggressively trimming forward, your attitude indicator is showing excessive pitch up, stick shaker is going on, you continuously keep overriding the nose down pitch with your stab trim. As I understand from the little information we got about the MCAS, you can override the auto trim forward with your stab trim switch, but the moment you let go off the switch it immediately trims back down. So you have the trim spinning back and forth (thus the oscillations in both accidents) at low altitude and low airspeed. No memory items to turn of the stab trim cutout switches. Not too much time to run QRH, not enough training and information about the system. Some say the other crew that brought the Lion Air airplane the day prior successfully ran the checklist and turned the stab trims switches off. It's true, but they were much higher, during a descent with completely different aircraft energy and attitude. Think what you want, but I consider blaming the crews for being not experienced or not well trained as scapegoating. I think Boeing created the problem and they should assume the responsibility. And for all you great aviators that have so much experience, think about what they went through right after you take off. Add night conditions or IMC if you like...
The way I understand it, MCAS is disabled with the autopilot on or flaps extended. Seems putting the flaps back to 1 would stop the MCAS also
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Old 03-15-2019, 01:24 PM
  #74  
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Based on the information that is available at this point I would say the 737 Max is safe. The preliminary report on Lion Air Flight 610 states that the previous crew dealt with the same failures and handled them according to the way every 737 pilot is trained: Airspeed unreliabe and runaway stabilzer memory items:

The PIC cross checked both PFDs with the standby instrument and determined that the left PFD had the problem. The flight was handled by the SIC.

The PIC noticed that as soon the SIC stopped trim input, the aircraft was automatically trimming aircraft nose down (AND). After three automatic AND trim occurrences, the SIC commented that the control column was too heavy to hold back. The PIC moved the STAB TRIM switches to CUT OUT.


An interesting fact is that the crew suspected the runaway stabilzer was caused by the speed trim system since they did not know about the existence of MCAS. The Pic wrote in the Tech log:

STS* also running to the wrong direction, suspected because of speed difference


This shows that even though the crew wasn't aware of the MCAS system they still knew how to handle it malfunctioning, which makes sense to me since it doesn't matter what causes a stab trim runway it just matters to stop it from happening (nonetheless I share the criticism that Boeing should have made crews aware of the system).
I would hate to have unreliable airspeed coupled with trim runaway but the Lion Air 610 crew was in the air for more than 10 Minutes which seems like enough time to to set the stab trim cut out switches to cut out.

As opposed to the way the media is reporting it, the MCAS System isn't going to be active in a normal flight. It is a system that will aid in a critical situation which under normal circumstances will not occur. If a system that is designed to aid the pilots malfunctions it is our job to recognize this and shut off the system. This I believe is not going to change anytime soon.
Nonetheless I do agree that it would be an improvement if MCAS received information from both AOA sensors.

About the reports that several pilots already faced problems with the MCAS system as was spread by news media througout the world. Looking at the reports the Dallas morning news refered to, they misinterpreted the reports. There is one report about the autopilot behaving unusual after it was engaged. There were two reports made about this one incident: one by the Captain and one by the First Officer. The media falsely reported this as two seperate events. Furthermore, according to our present knowledge MCAS will not be activated when the AP is engaged and the crew even wrote that they cannot rule out a mismanagement of the AP. The other reports about not setting FL 360 when cleared to this level or the thrust not being set as expected are the kind of reports that you will find plenty of for any given airplane.
So we are left with no report concerning a malfunctioning MCAS experienced by US pilots which is the opposite of what the media reported (one pilot rightly complained about the lack of documentation for MCAS).
Considering that we do not know yet what caused the Ethiopian crash and that the information about the Lion Air crash suggests that it was preventable, I find the grounding of the 737 Max unjustified and believe the airplane is safe to fly.

Last edited by Arrow50t; 03-15-2019 at 01:54 PM.
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Old 03-15-2019, 05:03 PM
  #75  
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It will come down to certification basis.
Boeing, at the request of SWA, Alaska Airlines and to a varying degree the big Three, rushed out a response to the A320/321 NEO.
In doing so they discovered that a big under-slung engine on a longer pylon created deleterious effect on maneuver margins near the edge of the envelope. Lacking any type of an intelligent maneuver-assistive FCC they strapped one on to essentially a manual system. And broke all their own rules about critical Flight Control design. Single source, no fail-safe, no comparator, no false-input control. Nothing but a QRH. Having pushed up against the limits of simple common type, they and their airline partners convinced the FAA that these changes were simple and not only did not require training but really only mechanics need know of them. No need to point it out to pilots as it would just confuse them. Nothing should happen and if it does it will be hidden under the general Runaway Stabilizer Trim QRH...
 
Old 03-15-2019, 05:06 PM
  #76  
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No question that all of us with extensive experience could wrangle the jet into submission and go land. But the certification basis requires the 200hr guy to wrangle the jet noy us
 
Old 03-15-2019, 05:08 PM
  #77  
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Breach of Faith, loss of confidence by airlines, Boeing and the FAA for sure. Unflyable jet...by no means
 
Old 03-16-2019, 07:53 AM
  #78  
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MCAS I think was a good idea but poorly implemented.

First - it should be disabled and not activate if there's an airspeed disagree or any detected issue with AOA indicators. That's a simple fix. Frankly this system activating during such a circumstance is just exacerbating an already existing emergency.

Second - it should not be allowed to get to full nose down trim below a specific altitude - Boeing can decide what that altitude is but I'd say 10000 feet and certainly not 6000.

The purpose of MCAS is to help with stall recovery with high power settings. Tests could be performed to determine what the max nose down trim should be with full power, but I'm certain it's not FULL nose down trim. Limit it.

I think that this can be fixed and the fleet safely returned to service. I'm sure smarter people than me at Boeing have already considered what I'm proposing.
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Old 03-16-2019, 08:24 AM
  #79  
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Interesting that the FAA’s B-737 Flight Standardization Board Report (FSB Report) does not identify any required Differences Training or Special Emphasis Items with respect to the MCAS system on the -Max vesus previous models?

www.fsims.faa.gov, under Publications, FSB Reports, Boeing.
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Old 03-16-2019, 08:30 AM
  #80  
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I still want to know if in fact the two crews were approaching stall conditions in the first place.

Now the investigators are arguing over stuff and walking out of meetings in France. Hopefully the real answers come out.
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