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Ethiopian 737 MAX 8 crash

Old 03-11-2019, 04:33 PM
  #111  
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Originally Posted by rickair7777 View Post
My understanding of MCAS is that it drives nose-down trim in the event of a stall condition, and it was a fix required for certification of stall characteristics. Problem is it looks like one faulty sensor will trigger the MCAS, and I think also stall warnings. So you get a lot of distractions while MCAS is driving trim nose down. Might not notice it instantly, or might not recognize that it's a malfunction vice a legit reaction to stall (by either pilot or automation).

I can understand how the lion air guys got in trouble, not knowing what they were dealing with. At this point I would think all MAX pilots would be spring-loaded on this issue. If not yesterday, they should be today.
I must say, the single point failure mode is hard to understand how it got certified.

GF
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Old 03-11-2019, 04:39 PM
  #112  
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Originally Posted by 123494 View Post
Should be a good time to buy Boeing stock
Yes, they have a huge order backlog and this should be a (relatively) easy fix. Boeing was apparently trying to save face by blaming the installed scapegoats (Installed 2, Required 2), but that's now water under the bridge. Might as well fix it now before they rack up any more multi-billion lawsuits.
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Old 03-11-2019, 04:52 PM
  #113  
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Originally Posted by galaxy flyer View Post
I must say, the single point failure mode is hard to understand how it got certified.

GF
Part 25 says failures like these should be "extremely improbable", which is defined as never to occur during the life of the whole fleet.
Boeing has a lot of questions to answer.
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Old 03-11-2019, 05:22 PM
  #114  
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Originally Posted by rickair7777 View Post
My understanding of MCAS is that it drives nose-down trim in the event of a stall condition, and it was a fix required for certification of stall characteristics. Problem is it looks like one faulty sensor will trigger the MCAS, and I think also stall warnings. So you get a lot of distractions while MCAS is driving trim nose down. Might not notice it instantly, or might not recognize that it's a malfunction vice a legit reaction to stall (by either pilot or automation).

I can understand how the lion air guys got in trouble, not knowing what they were dealing with. At this point I would think all MAX pilots would be spring-loaded on this issue. If not yesterday, they should be today.
MCAS only works when hand flying, and the 737 has those big loud trim wheels. So if MCAS is working, the trim wheels are spinning loudly nose down, while the yoke is being pulled from your hands. It would be hard not to notice.

Admittedly your first reaction would be to pull back, which is what MCAS is trimming to prevent (because the plane thinks you are stalling). But if the trim wheels are spinning and you aren't trimming, then it seems like stopping them would be pretty desirable in the moment. Electric trim will supposedly override the MCAS, as will the trim cutout switches on the pedestal.
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Old 03-11-2019, 05:30 PM
  #115  
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Originally Posted by ORDinary View Post
MCAS only works when hand flying, and the 737 has those big loud trim wheels. So if MCAS is working, the trim wheels are spinning loudly nose down, while the yoke is being pulled from your hands. It would be hard not to notice.

Admittedly your first reaction would be to pull back, which is what MCAS is trimming to prevent (because the plane thinks you are stalling). But if the trim wheels are spinning and you aren't trimming, then it seems like stopping them would be pretty desirable in the moment. Electric trim will supposedly override the MCAS, as will the trim cutout switches on the pedestal.
But if you think you're stalling, you might want to let MCAS do it's thing. The problem is when it starts spinning you don't know when it will stop.

If it's an actual stall, it will stop trimming soon enough I believe.

If it's a failed AoA sensor, then it will apparently not stop trimming.

If you also get stall warnings then both scenarios start the same, and memory items presumably do not call for hauling back on the yoke as hard as you can in the event of stall indications... that's so 2009.
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Old 03-11-2019, 05:41 PM
  #116  
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Half a dozen witnesses interviewed by Reuters in the farmland where the plane came down reported smoke billowing out behind, while four of them also described a loud sound.

Malka Galato, 47, a barley and wheat farmer whose field the plane crashed in, also described smoke and sparks from the back. “The plane was very close to the ground and it made a turn... Cows that were grazing in the fields ran in panic,” he said.

Tamirat Abera, 25, was walking past the field at the time. He said the plane turned sharply, trailing white smoke and items like clothes and papers, then crashed about 300 meters away.

https://www.reuters.com/article/us-e...-idUSKBN1QS1LJ
Interesting if true. But...eyewitness accounts are notoriously inaccurate.
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Old 03-11-2019, 06:21 PM
  #117  
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Originally Posted by rickair7777 View Post
That was never typical. Mesa did it, and a couple others would hire well under 1500.
the ebb and flow of supply and demand in the industry has allot to do with how deep the applicant pool is and what their qualifications are.

In the low to mid 1990's it took over 2,500 hours and 1000 multi engine to land a job at a low paying commuter.

After Vietnam there was an over abundance of unemployed military aviators.

After WWII there was lots of prior service pilots looking for work who were plenty experienced.

Now a days, the military ain't pushing em out.

The answer is not "lowering" of flight time just to suit market conditions because airline XYZ needs a pilot. The answer is having properly experienced pilots in the right new hire positions to work their way up the ladder.

Just because it used to happen (zero time and low time) doesn't make it right, smart, or prudent. The learning curve can be very steep, and if in the wrong set of circumstances that mountain may be too high to climb. Why set someone up to fail, or to suffer? Learning by gaining experience in an incremental fashion is the right way.
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Old 03-11-2019, 06:35 PM
  #118  
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Originally Posted by ORDinary View Post
MCAS only works when hand flying, and the 737 has those big loud trim wheels. So if MCAS is working, the trim wheels are spinning loudly nose down, while the yoke is being pulled from your hands. It would be hard not to notice.

Admittedly your first reaction would be to pull back, which is what MCAS is trimming to prevent (because the plane thinks you are stalling). But if the trim wheels are spinning and you aren't trimming, then it seems like stopping them would be pretty desirable in the moment. Electric trim will supposedly override the MCAS, as will the trim cutout switches on the pedestal.
It all sounds simple on paper. For better or worse I’ve got probably 8,000 hours in the Guppy (with the associated hearing loss), and I can thoroughly symphatize with these crews. IF the sole event was MCAS trimming forward and the yolk getting pulled from your hand, then it would be easy enough to diagnose as a STAB TRIM runaway and quickly reach for the cutout switches.

Unfortunately, at least in the case of the Lion Air accident, those poor bastards were dealing with sensory overload and I can easily see how they would have missed the airplane trimming forward.

Anymore, those of us that fly the MAX will be hair-triggered to reach for the cutout switches the moment the chit hits the fan.

At least from the -800 on down the B737 is a cream puff and if you’ve taken the time and made the effort to hand fly her enough she should be controlable in pitch, power and manual trim to the point of getting her on the ground safely.

I hand fly a lot and feel really comfortable with seat of the pants in that particular airplane but am making a renewed vow to make mental snapshots of pitch angles and power settings at commonly used configurations during flight in the hopes that if this ever happened to me (us), we’d have a fighting chance.

Those poor people in the cockpit and especially in the back. My heart is broken for them and the sheer terror that a human has to deal with in those final moments when they know they’re going to die. Just awful....
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Old 03-11-2019, 06:56 PM
  #119  
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Originally Posted by ORDinary View Post
Source? Post some real numbers if you are going make claims like that.


Don’t be “SOURCE??” Guy. It’s annoying.
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Old 03-11-2019, 07:06 PM
  #120  
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Originally Posted by F4E Mx View Post
Are 2 airframes lost out of 350 delivered real enough for you? That is a .6% loss rate right there.
It's not good enough for me, and it's not good enough to make such an unsubstantiated, speculative, uninformed statement as you have.

Two aircraft mishaps, as yet for reasons unknown; the investigation is incomplete.

Originally Posted by Boatfly View Post
Looks like Boeing is playing Tic Tac Toe. How many 737 crashes does it take before they have enough Xs on the world map to fix this flaw?

If these crashes are because of a faulty AOA sensor and an automatic flight control input of countering a perceived stall, it is an unsafe and poorly designed system. Just imagine you rotate on takeoff and suddenly the airplane pitches down because of a faulty AOA sensor. If Lockheed had this on C141s I would have splashed in the Indian Ocean when I had a faulty AOA on rotation.

This is very bad for Boeing.
Good thing there's no need to waste time, money and effort on an investigation, when you've already got it figured out. You should tell someone.

Or you could wait until the investigation is complete before guessing at the cause and calling or correction to an unknown problem.
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