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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 11th Mar 2019, 15:05
  #361 (permalink)  
 
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Originally Posted by ManaAdaSystem View Post


Fuel contamination, engine problems, flight control problems, terrorism, instrument problems, birdstrike, suicide, runaway trim ? Nothing can be excluded, but ony one issue is discussed.
MCAS.
Performance problems have been discussed earlier in this thread, but do not seem to be the cause with the information we have now (as the forward speed was steadily increasing).
Also, there have been rumours about an ATC call to return due to an unreliable airspeed indication.

With this in mind, and also the strong resemblance to the Lion Air flight, it is not so strange that the main focus is on the very system that caused Lion Air to go down.
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Old 11th Mar 2019, 15:06
  #362 (permalink)  
 
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Originally Posted by GoingAroundAgain View Post
Agreed. People should have some relevant aviation involvement as crew, engineer, atc, ops etc to post in this group.
Utter nonsense!

Some of the best contributions I have seen on this forum in nearly 20 years, have come from psychologists, educationalists, electronics engineers, geographers, training specialists, management theorists, data and IT engineers, physicists and chemists, manufacturing experts, metallurgists and logicians, non of whom had any aviation involvement.

Speed of Sound is offline  
Old 11th Mar 2019, 15:06
  #363 (permalink)  
 
Join Date: Nov 2015
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I looked up the history of ET-AVJ on Flightradar24 and noticed that 2 days before the crash, there was an anomaly in it's flight routine. Can anyone shed some light on what that might have been? Looks like ET2860 and 2861 were the flight numbers. I looked up some other tail numbers of ET planes on that similar routing and didn't see any logging of movement with non-existent flight numbers. Could it have been a maintenance issue being tested during that time?
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Old 11th Mar 2019, 15:09
  #364 (permalink)  
 
Join Date: Oct 2003
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I understand the 737 (at least since the CFM56 variants) has been somewhat pitch sensitive to power changes, but I'm curious about the underlying need for MCAS, as per this article:

At high angles of attack the CFM Leap-1B’s engine nacelle generates its own lift.
(source: https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610/)

It must be quite an increase in moment to justify a protection system.

Only a singular AOA input. and a failure mode that might be riskier than the problem it is trying to solve? Hmm...


JamesT73J is offline  
Old 11th Mar 2019, 15:10
  #365 (permalink)  
 
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Originally Posted by ManaAdaSystem View Post


Fuel contamination, engine problems, flight control problems, terrorism, instrument problems, birdstrike, suicide, runaway trim ? Nothing can be excluded, but ony one issue is discussed.
MCAS.
Thank you.

Condolences to the friends and family of the passengers and crew. Why don’t we let them Rest In Peace while the investigators sort this out.

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Old 11th Mar 2019, 15:15
  #366 (permalink)  
 
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As a former B737 driver ( some decades ago ) I followed the Ethiopian Airlines fatal accident in Beirut in 2010. The cause of the accident was pilot errors. The Lebanese accident Investigation board suggested that Ethiopian Airlines look into there crew composition ( experience ) and CRM. Being it MCAS or any other cause of this accident, as a former B737, Airbus and currently a Boeing driver I have the sneaky suspicion that crew composition and CRM played a major role in this accident.
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Old 11th Mar 2019, 15:15
  #367 (permalink)  
 
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Originally Posted by Rananim View Post
You dont design for the best crews though,you design for the mere mortals.
Well, in theory you should design to be safe for the worst crews on their worst days. Even if something is designed to be usable by the "average crew", nearly half of your pilots on a given day will be below the level that you designed for. And even the average ones or the best ones can be stressed or startled or sleep deprived or all three.

So either the design has to be - quite literally, fool proof - or the training has to be consistently good.
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Old 11th Mar 2019, 15:16
  #368 (permalink)  
 
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I really am mystified that a device that arguably insidiously pitches the aircraft down even if cancelled during a potentially high workload situation and which relies of only one of two AOA sensors ever gained certification. Did the certifying authority fully understand MCAS - how explicit were Boeing in the certification process? Or am I interpreting incorrectly

Surely the STS is different - that is making small corrections both ways towards a desired situation.
22/04 is online now  
Old 11th Mar 2019, 15:26
  #369 (permalink)  
 
Join Date: Aug 2015
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Originally Posted by TriStar_drvr View Post


Thank you.

Condolences to the friends and family of the passengers and crew. Why don’t we let them Rest In Peace while the investigators sort this out.

Easily the most sensible and correct post I have read so far.
Speculation is just that. All will be revealed in good time.
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Old 11th Mar 2019, 15:30
  #370 (permalink)  
 
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Did the certifying authority fully understand MCAS ?

There has to be mutual trust for certification to take place on time. I don't know but I doubt that
the personnel of the FAA Regional Office in Renton WA are hostile to their Boeing counterparts.
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Old 11th Mar 2019, 15:37
  #371 (permalink)  
 
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Originally Posted by NWA SLF View Post
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.
Not really. The crew put that aircraft into a stall after they failed to apply basic aeronautical techniques for stall recovery.

Big difference between that and an aircraft pitching uncontrollably nose down at low altitudes.
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Old 11th Mar 2019, 15:39
  #372 (permalink)  
 
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Now is probably a great time to buy Boeing shares. I have rarely seen such utter tripe talked over two accidents that look, at least at first glance, to be caused by sub standard pilots getting caught by the same tricky but surviveable system failure. Read the 3$%^&ing Boeing AD! Another reason to stop putting undertrained muppets in airline pilot seats.

P.S To ‘Rananim” a pilot of a large passenger jet will NOT be able to distinguish between a faulty sensor and a “real” stall since the aircraft is not certified to stall at all, it is never intended to be stalled, nor does it provide the physical warnings of an incipient stall. That is the reason for all those stall protection systems! That is also the reason for extensive training on systems and their failure modes.
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Old 11th Mar 2019, 15:41
  #373 (permalink)  
 
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Am I right that the original triplex concept (3 computers using different microprocessors, three different OSs, three different languages and code written by three different teams who don't communicate with each other - a bug in anything means two against one, and the two win) was abandoned long ago? Maybe it should be revisited.
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Old 11th Mar 2019, 15:41
  #374 (permalink)  
 
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Originally Posted by Speed of Sound View Post


Utter nonsense!

Some of the best contributions I have seen on this forum in nearly 20 years, have come from psychologists, educationalists, electronics engineers, geographers, training specialists, management theorists, data and IT engineers, physicists and chemists, manufacturing experts, metallurgists and logicians, non of whom had any aviation involvement.

Maybe just prevent journalists from getting on?
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Old 11th Mar 2019, 15:43
  #375 (permalink)  
 
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Originally Posted by 22/04 View Post
I really am mystified that a device that arguably insidiously pitches the aircraft down even if cancelled during a potentially high workload situation and which relies of only one of two AOA sensors ever gained certification. Did the certifying authority fully understand MCAS - how explicit were Boeing in the certification process? Or am I interpreting incorrectly

Surely the STS is different - that is making small corrections both ways towards a desired situation.
That is a question requiring answering regardless of this ET crash. It is hard to believe how this logic made it through. For this to be fail safe, it would require 3 sources of data being evaluated. That way there is always an arbitration value. ie Capt side AoA, FO side AoA then a third AoA value not connected with Capt or FO. If this was in place the automated decision making process could evaluate 3 inputs and discard the erronous one.

At present even if there was error checking based on the non-flying side, how is it validated?
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Old 11th Mar 2019, 15:46
  #376 (permalink)  
 
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Originally Posted by Sunfish View Post
Now is probably a great time to buy Boeing shares. I have rarely seen such utter tripe talked over two accidents that look, at least at first glance, to be caused by sub standard pilots getting caught by the same tricky but surviveable system failure. Read the 3$%^&ing Boeing AD! Another reason to stop putting undertrained muppets in airline pilot seats.

P.S To ‘Rananim” a pilot of a large passenger jet will NOT be able to distinguish between a faulty sensor and a “real” stall since the aircraft is not certified to stall at all, it is never intended to be stalled, nor does it provide the physical warnings of an incipient stall. That is the reason for all those stall protection systems! That is also the reason for extensive training on systems and their failure modes.
What extensive training on MCAS and its failure modes?
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Old 11th Mar 2019, 15:51
  #377 (permalink)  
 
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(pax)Was looking for the unreliable airspeed drill for the 737 and found this
737 airspeed unreliable QRH
Can I ask if the -8 differs ?
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Old 11th Mar 2019, 15:52
  #378 (permalink)  
 
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Originally Posted by bucoops View Post
Maybe just prevent journalists from getting on?
Journalists tend not to involve themselves in discussions but prefer to just lift chunks of it, often out of context, and don't even have to register as this is a public site.
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Old 11th Mar 2019, 16:06
  #379 (permalink)  
 
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Originally Posted by OLVpilot View Post


Not really. The crew put that aircraft into a stall after they failed to apply basic aeronautical techniques for stall recovery.

Big difference between that and an aircraft pitching uncontrollably nose down at low altitudes.
A aircraft with uncommanded trim does not pitch uncontrollably nose down. As the trim motor adds nose down trim up elevator can compensate until the stabilizer overpowers the elevator. At that point the nose will start down. Normally it’s a smooth progression unless the aircraft is on autopilot. The autopilot disengaging with a out of trim condition will cause a more violent pitching moment. Prior to that however there should be several warning signs. The fix takes about 1 second to activate and the flight should be able to continue with manual trim. Had it happen on a 727. It was a non issue. Trim ran away nose down, trim disconnected and flight continued.
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Old 11th Mar 2019, 16:08
  #380 (permalink)  
 
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Originally Posted by Snyggapa View Post
Well, in theory you should design to be safe for the worst crews on their worst days. Even if something is designed to be usable by the "average crew", nearly half of your pilots on a given day will be below the level that you designed for.
In technical certifications, we create three standard candidates for the test we're about to write:

- The Clearly Acceptable Candidate: this is a candidate who should pass the exam with minimal to no preparation;
- The Minimally Acceptable Candidate: this is a candidate who should pass the exam with some preparation. Some will pass with high marks, while some will score the cut-score or just above;
- The Not Acceptable Candidate: this is a candidate who lacks the proficiency to pass the exam and should fail;

Any system that you design should be built to the specs of the Minimally Acceptable Candidate: someone who is unfamiliar with the matter (let's say, a pax) does not necessarily need to understand the system. However, those who are trained and licensed to fly should be able to understand the system without much difficulties. If one needs to be an expert on the system itself in order to use it, it is by definition unusable.

Similar to the big internet. Everyone reading this uses the internet, but I doubt more than 1% will even remotely know what a BGP community is. And that's fine, because this system was designed for the "average" user.

When I passed my Private's checkride, I had a reasonable understanding of the 172 I was flying. Engine, electrical systems, flight controls, instruments; the lot. I even understood the workings of the shimmy dampener (it does help if you fly an aircraft with a broken shimmy for a change). Any airman should be able to understand MCAS, or any other flight system for that matter, even on a bad day. If not, then either the system is too complex and risky to introduce, or the airman should not have received their license and rating(s).
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