B737MAX [Grounded as of 13 March 2019]

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Old Jun 19, 19, 1:24 am   -   Wikipost
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United does not fly the 737 MAX 8 that has been involved in two recent crashes, but it does operate the 737 MAX 9.

How to tell if your flight is scheduled to be operated by the MAX 9:

View your reservation or flight status page, either on the web or on the app. United lists the entire aircraft type. Every flight that is scheduled to be on the 737 MAX will say "Boeing 737 MAX 9." If you see anything else -- for example, "Boeing 737-900," it is not scheduled to be a MAX at this time.

The same is true in search results and anywhere else on the United site.

For advanced users: UA uses the three letter IATA identifier 7M9 for the 737 MAX 9.

All 737 MAX aircraft worldwide (MAX 8, MAX 9, and MAX 10) are currently grounded.
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Old Apr 5, 19, 7:19 am
  #1051  
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Originally Posted by Bear96 View Post
Last I heard (which was a week or so ago now so maybe this has changed) they were still rolling new MAXs off the production line and looking for places to store them because they can't deliver any. They might want to shut the line down for a bit, at least until the new planes can be produced with whatever fixes will finally be made.
I have an uncle who is the CEO of a parts manufacturer that is in the supply chain for the GE engines on the MAX and they've been told that there are zero plans to alter production for the foreseeable future. In talking with a large hedge fund PM in $BA the industry is really of the view that airlines simply can't really move away from BA because of the backlog issue. Airbus really can't ramp their production more than a handful of planes a month and so as an airline you can either pay way up for those increased slots or you can push out your aircraft delivery plans by multiple years. Neither of those options are easy or cheap. I'm personally in the camp that this is going to be a huge financial deal for BA but everyone that knows more about this than me keeps telling me that it will only be the case if this safety issue is still perceived to exist a year or more from now because that's the kind of leeway this decision cycle has.
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Old Apr 5, 19, 7:26 am
  #1052  
 
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Originally Posted by worldclubber View Post


Not necessarily. Creating something from scratch considering only parameters that are well-known to make a plane stable can be better than tweaking a known design to its limits to safe money/fuel/...

Very little in aviation is created from scratch. The 777 and 787 had new design processes, technology and systems and faces incredible teething pains. Aircraft with more incremental enhancements, the A350, Neo, and MAX tend to be more reliable as you’re dealing with systems and technologies that have known behavior. Occasionally there are problems, as we unfortunately see today. The aviation industry has historically learned from tragedy and instituted changes and reforms that impact future designs, production and operations.
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Old Apr 5, 19, 7:27 am
  #1053  
 
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Originally Posted by Bear96 View Post
Looking ahead long-term, they know that most transport aircraft deliveries will be to non-US / "third-world" countries / China, and have realized that it might not be a good sales tactic to blame the lack of skill, experience and training of pilots in those countries or to imply that only US pilots are skilled enough to handle their finicky planes.
Hope they realized that now, because they did not after the Lion Air crash. And they knew about the shift in the market, as they published an outlook early in 2018 that shows they knew.
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Old Apr 5, 19, 9:03 am
  #1054  
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Originally Posted by fly18725 View Post
The aviation industry has historically learned from tragedy and instituted changes and reforms that impact future designs, production and operations.
In other words, they beta test on humans. Tombstone mentality.
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Old Apr 5, 19, 9:36 am
  #1055  
 
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Originally Posted by n198ua View Post
So if you lockout the jackscrew in full nose-down orientation, how long would it take to manually adjust it to a neutral flying position ?
A long time. The key is not allowing a runaway to progress that far and put you in that situation. Use the primary electric trim to keep the stab close to in-trim while doing the stabilizer runway procedure.

Originally Posted by jmastron View Post
Do we know if MCAS stops trimming down during the entire time the pilot is holding the electric trim switch
Yes. Both because that is how it is supposed to work and that is how it did work (DFDR data) on the Lion Air accident flight as the Captain kept the airplane in-trim through 21 MCAS activations through the use of the primary electric trim.
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Old Apr 5, 19, 10:13 am
  #1056  
 
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Originally Posted by LarryJ View Post
The key is not allowing a runaway to progress that far and put you in that situation. Use the primary electric trim to keep the stab close to in-trim while doing the stabilizer runway procedure.
But if for whatever reason you allowed it to get far out of trim and then do the memory items for stab runaway - I watched Mentourpilot's video again - according to that, the memory items are:
1) hold controls firmly
2) disengage autopilot
3) disengage autothrottle
4) if problem not yet solved, cut out the electric trim

At this point you're in big trouble, because the only option is to use manual trim, right?
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Old Apr 5, 19, 10:40 am
  #1057  
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Originally Posted by DenverBrian View Post
Even if they "fix" the plane, it'll be years now before I ever set foot on one. I'm not interested in being a guinea pig. No hysterics, no panic; I will simply book away from flights where the MAX is on the schedule, and if a swap occurs, I'll spend the $75 or whatever to swap myself back to a non-MAX.
I flew on many DC-10’s back in the day. I flew on an A330 shortly after the AF issue over the South Atlantic. I’ll fly on a MAX once they are back in the air.
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Old Apr 5, 19, 10:57 am
  #1058  
 
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Originally Posted by lazytom View Post
But if for whatever reason you allowed it to get far out of trim and then do the memory items for stab runaway - I watched Mentourpilot's video again - according to that, the memory items are:
1) hold controls firmly
2) disengage autopilot
3) disengage autothrottle
4) if problem not yet solved, cut out the electric trim

At this point you're in big trouble, because the only option is to use manual trim, right?
I wouldn’t necessarily say you’re in big trouble. Plane flies fine using only manual trim. Issue here is the MCAS forced the trim in an extreme nose down position if autotrim is kept engaged (or re-engaged as with ET). Both pilots need to work together to get the trim back into a normal range.

Do I feel Boeing is at fault for the engineering of MCAS and the lack of information distributed to its customers...absolutely! However, the recovery procedure is nothing new and I still do feel this was a recoverable situation based on my experience in the plane.

Every Boeing 737 type rated pilot has worked a runaway trim scenario in the simulator. If I recall it was sim session 2 or 3 during my type certification at Continental. I imagine the FAA will require this demonstration to be done at a lower, more critical altitude for future training curriculums because of this event.


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Old Apr 5, 19, 11:24 am
  #1059  
 
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Originally Posted by worldclubber View Post


Not necessarily. Creating something from scratch considering only parameters that are well-known to make a plane stable can be better than tweaking a known design to its limits to save money/fuel/...



And, the 737-MAX and 777-X (Big MAX) appear to reflect more than "tweaking" or "modifying." With the 737 MAX they are placing much larger engines higher and more forward of the modified wing, on a plane designed for much smaller engines, generating a lot of aerodynamic issues being addressed with software. What was needed was a much higher landing gear. The United 737-200 is one of the first planes that I flew almost 50 years ago with much smaller engines balanced under the wings. Google a picture of the 737-200 and compare it to the 737 MAX. I saw a post or article stating it is like Ford putting putting a much larger engine in & stretching the Model T. To think that the 737 is one of the first airplanes that I flew on almost 50 years ago, and that it may be one of the last airplanes that I fly on before I move on to final rest in the Great Sky, makes me wonder, could Boeing have done better & its customer airlines insisted on better?
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Old Apr 5, 19, 11:25 am
  #1060  
 
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Originally Posted by halls120 View Post
I flew on many DC-10’s back in the day. I flew on an A330 shortly after the AF issue over the South Atlantic. I’ll fly on a MAX once they are back in the air.
And like the rest of us, you probably drive or walk on public streets every day, which is far more dangerous.
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Old Apr 5, 19, 12:12 pm
  #1061  
 
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Originally Posted by LarryJ View Post
A long time. The key is not allowing a runaway to progress that far and put you in that situation. Use the primary electric trim to keep the stab close to in-trim while doing the stabilizer runway procedure.
Pardon my ignorance with the next question as I am not an ATP or even multi-engine pilot. If you lockout the stab in full "nose-down" deflection, then hold the yoke as far back as possible, all other forces being equal, would you be able to fly the aircraft at least somewhat nose level ? Or, once that stab is fully deflected down, is your 737 "going down" as well ?

Also, on an unrelated note: well done to everyone who has thoughtfully contributed to this thread. I've been a FT'er since Nov of '06 and this is one of the best conversations we've had around here in a long time. 1100+ replies, that's awesome. Thanks everyone.
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Last edited by n198ua; Apr 5, 19 at 12:20 pm
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Old Apr 5, 19, 12:28 pm
  #1062  
 
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Originally Posted by BF263533 View Post
Google a picture of the 737-200 and compare it to the 737 MAX.
No need to google it, I remember the engines frequently referred to as „cigar“ very well. Flew on those noisy bast... many times.

The current landing gear was just not made for much larger engines.
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Old Apr 5, 19, 12:31 pm
  #1063  
 
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Originally Posted by clubord View Post


I wouldn’t necessarily say you’re in big trouble. Plane flies fine using only manual trim. Issue here is the MCAS forced the trim in an extreme nose down position if autotrim is kept engaged (or re-engaged as with ET). Both pilots need to work together to get the trim back into a normal range.

Do I feel Boeing is at fault for the engineering of MCAS and the lack of information distributed to its customers...absolutely! However, the recovery procedure is nothing new and I still do feel this was a recoverable situation based on my experience in the plane.

Every Boeing 737 type rated pilot has worked a runaway trim scenario in the simulator. If I recall it was sim session 2 or 3 during my type certification at Continental. I imagine the FAA will require this demonstration to be done at a lower, more critical altitude for future training curriculums because of this event.


Does the simulator accurately replicate the force required to turn the manual trim wheels at the speeds involved in these incidents? And do at least some of the runaway trim scenarios involve full downward deflection before the pilots are allowed to start recovering (including feeling how much effort required to both turn the trim wheels and to hold the stick/yoke back), and do they include "surprise" runaway when the pilot doesn't expect it (as opposed to failing to stop when the pilot releases the electric trim switch so they realize more quickly )?

I don't mean those at all to sound like loaded questions; I'm genuinely curious and appreciate all of the real pilots who are adding their insight in this thread.
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Old Apr 5, 19, 1:45 pm
  #1064  
 
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Originally Posted by DenverBrian View Post
In other words, they beta test on humans. Tombstone mentality.
Non sequitur.

You can rigorously design and test and airplane only to discover flaws after it enters operation. It is not possible to be 100% safe. You learn from the problems, make changes so they don’t happen again, and move on. This doesn’t excuse the crashes or diminish the lives lost but it’s an extreme position where everything has to be safe or must not exist.

Last edited by WineCountryUA; Apr 5, 19 at 2:22 pm Reason: Discuss the issues, not the poster(s)
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Old Apr 5, 19, 1:56 pm
  #1065  
 
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Originally Posted by BF263533 View Post
And, the 737-MAX and 777-X (Big MAX) appear to reflect more than "tweaking" or "modifying." With the 737 MAX they are placing much larger engines higher and more forward of the modified wing, on a plane designed for much smaller engines, generating a lot of aerodynamic issues being addressed with software. What was needed was a much higher landing gear. The United 737-200 is one of the first planes that I flew almost 50 years ago with much smaller engines balanced under the wings. Google a picture of the 737-200 and compare it to the 737 MAX. I saw a post or article stating it is like Ford putting putting a much larger engine in & stretching the Model T. To think that the 737 is one of the first airplanes that I flew on almost 50 years ago, and that it may be one of the last airplanes that I fly on before I move on to final rest in the Great Sky, makes me wonder, could Boeing have done better & its customer airlines insisted on better?

There was radical change a long time ago as well. Take a look at a 737-300 vs a -200. Radical stretch / change from the cigar engines to the then larger forward weighted ones used until the Max.

And the 737-200 had its own flaws. Very prone to pitch up - was a factor in the stall that led to the Air Florida crash in DC (and also one as recently as 2012 in Pakistan). Pilots ultimately responsible, and a sensor was also involved, but the design of the aircraft and its unique handling characteristics played a memorable role.

Lots that can be done better - but are we certain a clean sheet airframe would be free of its own boundary pushing and flaws. Remember the induction of the Airbus A320 and its fly by wire.

I'll bet most of us though would have rather seen the 757 be updated.
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