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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 11th Mar 2019, 09:04
  #301 (permalink)  
 
Join Date: Aug 2017
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Given the data so far presented and whilst acknowledging the similarities to the Lion Air accident, it seems that the aircraft was fairly low to have reached a clean configuration given the high airfield elevation.

If it wasn’t clean then the MCAS wouldn’t be active?

Another consideration is loading error, the CoG is much further forward on the MAX when compared to the NG and it’s easy for the loaders to overlook this if they’re not used to handling both types, often the case when a new variant enters a fleet.

I fly both variants, on the NG we normally split the load 2/3rds in bay 3 and 1/3rd in bay 2 ( so for 2100kg of hold luggage/ cargo 1400kg in the aft and 700kg fwd hold) on the MAX that would push the CoG to far forward, in the MAX all of that would go in the rear.

I have had loaders load a MAX as though it was an NG and when I did the W&B on the EFB computer said NO, moved some passengers from zone B to C and computer said yes.

if the early FDR confirms same issue as Lion Air a grounding is likely until a fix installed.

either way I can’t see that Boeing would go with a follow on version of the MAX, a new clean sheet design rather than tweaking a 50 year old design and coming up with auto intervention systems to sort the problems by stretching the design life.

having said all that the MAX is a lovely aircraft to fly and still find the cruise fuel burns unbelievably low, my longest sector length so far is over 8 hours
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Old 11th Mar 2019, 09:05
  #302 (permalink)  
 
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Of course, the cynical amongst us may postulate that the main reason that Boeing implemented the stall avoidance MCAS software on this aircraft was to use a "Cheap-as-chips" and quick solution to an inherently unbalanced airframe caused by the fitting of new heavier, differently positioned engines, thereby getting it to market ASAP.

Surely, the trim correction should have been done before the aircraft left the ground, in the airframe design office.

N
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Old 11th Mar 2019, 09:06
  #303 (permalink)  
 
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I think he’s talking about the fact that AP engagement disables the MCAS, not trying to do you out of a
job.
I understand that zerozero. Pilots wouldn’t be looking for a career change because they think that they might be done out of a job, they’d be looking because the AP can barely fly the thing when on a normal profile let alone in a non-normal.
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Old 11th Mar 2019, 09:10
  #304 (permalink)  
 
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Originally Posted by 73qanda View Post
My question is, if the the MCAS starts to trim the nose down, can the AP be still engaged and save the situation?


Not in the Classic or NG. To engage the autopilot you need to release elevator pressure on the stick, otherwise it will not engage. So if you are pulling against an MCAS-inspired nose down trim, you cannot engage the autopilot. (MCAS gives 10 seconds or 2 degrees worth ofnose down trim for each input - which is a heIIava lot of trim input - and then just while you are wondering what is going on, it gives you another 10 seconds of nose-down trim.)

Silver
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Old 11th Mar 2019, 09:14
  #305 (permalink)  
 
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It's a great shame that the passengers and crew,once again, seem to becoming part of the test flight program.

I always thought it risky, the authorities agreeing to a new airframe type and new engine types, on the same aircraft. It seems my fears have been unfounded.

However, when the manufactures start "playing around" with the automation, I become quite concerned.

If it ain't broke, don't fix it comes to mind. Or is it now, fix it until it breaks?
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Old 11th Mar 2019, 09:30
  #306 (permalink)  
 
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Originally Posted by silverstrata View Post
There is this volumous clanking noise going on, as the huge great Titanic trim wheel (taken from the Ju-52) winds its way around. And the controls will need a great deal of pulling for normal flight (something like 50 to 60 kg of force), which is pretty much uncontrollable.
Yes, correct. But from what I understand is not what is happening in the case of the MCAS.
You do not get a continuous running of the trim wheel like in a trim runaway, so probably not so easy to understand, at least not as easy as some posters imply.
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Old 11th Mar 2019, 09:35
  #307 (permalink)  
 
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Originally Posted by AmuDarya View Post
Ethiopan Airlines says via Twitter:
Assuming no typos, is that difference in flight hours very unusual, or is it a case of a relatively new first officer being teamed up with an experienced colleague?
Given that relatively new first officers do exist, should they fly with experienced or new captains?
"200hrs [total] and already in the cockpit of a big plane" is another question, but in some parts of the world it is a reality. (I.e. Russia.)
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Old 11th Mar 2019, 09:39
  #308 (permalink)  
 
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I'll wait until the FDR and CVR are found and the contents reveal exactly what happened .But maybe with live data downloads, Boeing and the FAA already know ?
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Old 11th Mar 2019, 09:42
  #309 (permalink)  
 
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Couple of things,

If i have read correctly there is come kind of update Boeing is working on in regards to the MCAS system following JT610, what is this update meant to actually do and what is it meant to prevent?

What is the failure rate of an AOA sensor, lets say this crash is related to MCAS, 2 aircraft which are less than 4 months old to both have failures of the same sensor regardless of MCAS seems very odd to me?
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Old 11th Mar 2019, 09:43
  #310 (permalink)  
 
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Originally Posted by EIFFS View Post
Given the data so far presented and whilst acknowledging the similarities to the Lion Air accident, it seems that the aircraft was fairly low to have reached a clean configuration given the high airfield elevation.

If it wasn’t clean then the MCAS wouldn’t be active?
MCAS active @ 1000ft w/ retracted flaps.
Bird strike on non redundant single AOA sensor doesn't allow much time to negotiate.
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Old 11th Mar 2019, 09:46
  #311 (permalink)  
 
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Originally Posted by jantar99 View Post
Given that relatively new first officers do exist, should they fly with experienced or new captains?
"200hrs [total] and already in the cockpit of a big plane" is another question, but in some parts of the world it is a reality. (I.e. Russia.)
Europe as well.

I think the FAA is one of the only ones to require ATP for FO's.
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Old 11th Mar 2019, 09:51
  #312 (permalink)  
 
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Originally Posted by log0008 View Post
What is the failure rate of an AOA sensor, lets say this crash is related to MCAS, 2 aircraft which are less than 4 months old to both have failures of the same sensor regardless of MCAS seems very odd to me?
It takes just one bird to lose an AOA sensor - we had that happen just a couple of weeks ago on one of our NGs.

Last edited by xetroV; 11th Mar 2019 at 10:17.
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Old 11th Mar 2019, 10:09
  #313 (permalink)  
 
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Originally Posted by sonicbum View Post
You could expect those kind of comments from the average (non frequent flyer) passenger, not from somebody who claims to be a former airline pilot. THERE IS NO PROVEN EVIDENCE SO FAR that the Ethiopian accident has been caused by a technical issue that, despite having been WELL MANAGED (that is another very important point) by the flight crew, ended up in a disaster anyway.
There is, as yet, no proven evidence for the contrary view either - that the Ethiopian accident was not caused by a technical issue.

Only 350 of these birds have been delivered. Two have crashed, with what appears to be superficial commonalities, in less than 6 months.

I wouldn't necessarily avoid travelling on the type, but I wouldn't be critical of somebody who does.
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Old 11th Mar 2019, 10:22
  #314 (permalink)  
 
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Originally Posted by bumpy737 View Post
From what I understand one condition for the MCAS to work is manual flight. My question is, if the the MCAS starts to trim the nose down, can the AP be still engaged and save the situation?
MCAS only operates in very high (or faulty) AoA, which would probably prevent the AP from being engaged.
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Old 11th Mar 2019, 10:26
  #315 (permalink)  
 
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FYI. My employer has just sent out a message instructing its employees to avoid flying on 737 MAX 8 aircraft. The company has no aviation expertise, but has dozens, maybe 100s, of employees in the air at any given moment. I doubt if this is backed by a genuine risk analysis - I wonder if it will actually push pax onto smaller and possibly less well managed airlines ? I am sure lots of other organisations are doing the same; I think all airlines will have no choice but to ground this aircraft.
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Old 11th Mar 2019, 10:29
  #316 (permalink)  
 
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Ironic that members here who blame the MCAS system already are switching to A320s for their flights which also have the same type angle of attack sensors along with software to prevent a stall and have received faulty see also from sensors resulting in a fatal crash before the crew could respond. It was 10 years ago the A320 with 3 sensors had 2 freeze due to maintenance, the software selected those 2 to use neglecting the third working AOA sensor because it differed, put the plane into a stall preventing dive at an altitude from which the crew could not recover before plunging into the Med. darn Boeing copying AB.
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Old 11th Mar 2019, 10:33
  #317 (permalink)  
 
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Just looking at a profile picture of the 737 - 8 Max, it strikes even the mildly interested, that those huge new engines are positioned almost completely foward and clear of the leading edge of the wing. That must shove the Centre of Gravity of the aircraft way in front of the leading edge of the wing. That's non-standard for a start in a passenger aircraft. Usually the C of G is positioned on or just foward of the centre of lift. Yet the chord of the wing and the rear horizontal stablisers are ultra slim (To minimise drag and fuel costs) and presumably, therefore do not provide the same level of damping to movements in pitch in normal flight. A further consequence of narrow chord is that a small change in the angle of attack produces a large movement in the centre of lift, proportional to the chord, is it not ? A recipe for porpoising ?

IMHO, a compare and contrast of this airframe with its predecessors indicates the designers may have possibly pushed the principle of inherent aerodynamic instability to far and knowing this, have pressed the MACAS anti-stall software into service in a role it wasn't initially designed for. A possible subject for regulation ?

N.
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Old 11th Mar 2019, 10:34
  #318 (permalink)  
 
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welcome to Toulouse

Guys from Everett Factory in Seattle should come to Toulouse, France to see how auto trim work
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Old 11th Mar 2019, 10:36
  #319 (permalink)  
 
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BBC reporting "black box" flight recorder found.
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Old 11th Mar 2019, 10:36
  #320 (permalink)  
 
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Originally Posted by NAROBS View Post
Just looking at a profile picture of the 737 - 8 Max, it strikes even the mildly interested, that those huge new engines are positioned almost completely foward and clear of the leading edge of the wing. That must shove the Centre of Gravity of the aircraft way in front of the leading edge of the wing. That's non-standard for a start in a passenger aircraft. Usually the C of G is positioned on or just foward of the centre of lift.

N.
yes ... and it also increases the lift (increased wing area)
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