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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 11th Mar 2019, 10:37
  #321 (permalink)  
 
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I would like to note that Boeing appear have a suffered disproportionate number of crashes where their aircraft dived nose first into the ground:-
  • 737-200, UAL flight 585 (rudder problem)
  • 737-300, USAir flight 427 (rudder problem)
  • 737-800 FlyDubai flight 981 (loss of control during go around. Wikipedia indicates stabilizer trimming was involved)
  • 737 Max 8 Lion air flight 601 (suspected AOA/MCAS issue)
  • 767 Atlas Air Flight 3591 (unknown problem)
  • 737 Max 8 Ethiopian Airlines (unknown problem)
The only other incident I recall involved the Douglas (now Boeing) MD80 series.

Even though spread over many years, it does appear to be pattern, notwithstanding the very different causes involved. I cannot remember any of the competing airliners having similar problems - Fokker, BAC, Convair, Sud Aviation, Airbus etc.
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Old 11th Mar 2019, 10:38
  #322 (permalink)  
 
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One of the recorders found according to Ethiopian TV
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Old 11th Mar 2019, 10:38
  #323 (permalink)  
 
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It would be interesting to get an idea if anyone else has been having sensor and MCAS problems. We know that the Lion aircraft experienced issues over several days. It seems inconceivable that the Ethiopian aircraft could have experienced anything similar and it not be written up. There are however a number of similarities so far between the two 737 Max accidents. For example both were first flights of the day from the airline's home base. It is quite likely that a daily check would have been carried out by company maintenance personnel shortly before the flights (in the Lion case we know for sure). It is also quite possible the aircraft were powered down before the accident flights, which may or may not be relevant, but experience has taught me that odd gremlins can occur when powering up electronic systems. Both crews lost control shortly after takeoff and impacted terrain. We will find out pretty soon from the flight recorders what happened.

Should it turn out to be the same failure then this is going to be a huge problem for Boeing. I flew the NG for many years and it together with the 777 have had absolutely outstanding safety records and very successful production runs. To lose two brand new Max aircraft within such a short period of time will raise big issues for the program. I have to say that given the present uncertainty I would not go out of my way to fly on a 737 Max until things have been clarified.
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Old 11th Mar 2019, 10:43
  #324 (permalink)  
 
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Learned Contributors,
please excuse if this is considered thread drift. If this Ethiopian crash and the Indonesian previously covered on here are proved to be linked. Is
not it odd that out of the total number of B.738M departures since entry to service, no one has been subject to this upset and caught it without loss of life ? Especially since Indonesia as I expect all B.738 Max crews are looking out for a recurrence?
Your time and trouble much appreciated,
Be lucky
David
The Lion Air aircraft apparently experienced the same malfunction on the immediately preceding flight to that which ended with the accident but the crew responded correctly and recovered the aircraft. They wrote up the incident as caused by unreliable airspeed. Engineers changed some components, did a ground test and declared the aircraft serviceable.
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Old 11th Mar 2019, 10:49
  #325 (permalink)  
 
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For those fixated on the experience level of the first officer, have we stopped to think of the possibility that the information given out on his/her experience level may be false. So far the only official statement I have read or heard about the experience of the pilots is that of the captain which says he is a senior Captain who has been with Ethiopian for 9 years.

Lets think about this for a minute, 200 hours doesn’t making sense taking into consideration average time to qualify for a CPL, the average time for line training and to get checked out on line as a first officer or second officer at the airline or was this a line training flight with a training captain?

As is common knowledge and has always been said on here, having a low time pilot as a first officer straight out of flight school is not uncommon, this is practiced all over the world and so far without issues, lots of very experienced and very good captains today started that way, not every country has their aviation industry set up like the US to start off in the general aviation sector and work yourself up to the majors.
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Old 11th Mar 2019, 10:54
  #326 (permalink)  
 
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Originally Posted by silverstrata View Post


There is always a superman, who knws everything. But how many times have you operated these switches? I think I have touched them twice in 10 years. Still know which way they operate? And warnings going off all over the place; and the aircraft pitching up and down, possibly violently; and you only have 200 hours on type .... still know which way these switches operate...?

Silver

Runaway trim is a recall item. It doesn't take a superman to know the memory items it's a requirement of the job. Heaven forfend.
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Old 11th Mar 2019, 11:21
  #327 (permalink)  
 
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Unreliable airspeed at takeoff sounds like a pitot problem.
In many areas of africa there are small wasps which habitually try to set up home in pitots so pitot covers are fitted whenever an aircraft is on the ground.
Did someone forget to remove a cover ?

Just a random thought, it has happened before........
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Old 11th Mar 2019, 11:24
  #328 (permalink)  
 
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Both recorders found.
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Old 11th Mar 2019, 11:27
  #329 (permalink)  
 
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Where will the boxes be read? In Washington?

Also NTSB will be busy at the moment, currently JT610, GT3591 and now ET302 all underway and all very significant incidents.
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Old 11th Mar 2019, 11:28
  #330 (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.
This was an acceptance flight, the crew was rushed and did flight testing while on the approach (as opposed to doing it at 14.000ft, where they would have had time to recognize the fault). They deliberately attempted to stall the aircraft (if it had been a B737 it would have stalled too, and at 3000 ft probably would not have recovered either). Boeing didn't copy Airbus, Boeing's MCAS takes input from ONE AOA and allows it to run the trim all the way, in an Airbus you need 2 out of 3 to fail at the same time to get the same result (and the only reason 2 failed in your example is because MX didn't follow established procedure, not some unexpected design issue). "ironic" indeed....
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Old 11th Mar 2019, 11:31
  #331 (permalink)  
 
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Indonesia has grounded all 737 Max as well.
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Old 11th Mar 2019, 11:35
  #332 (permalink)  
 
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Originally Posted by arketip View Post
Yes, but from what I understand, the MCAS does not behave/look like a runaway trim

Correct, it is different from the scenarios we normally practice in sim.

And on top of that, it comes with airspeed unreliable indications and stickshaker, which draws a lot of attention to them in an already high workload phase of flight.
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Old 11th Mar 2019, 11:41
  #333 (permalink)  
 
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Originally Posted by SigWit View Post



Correct, it is different from the scenarios we normally practice in sim.

And on top of that, it comes with airspeed unreliable indications and stickshaker, which draws a lot of attention to them in an already high workload phase of flight.
What is different?
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Old 11th Mar 2019, 11:44
  #334 (permalink)  
 
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Originally Posted by Azgalor View Post
What is different?
How we normally detect and identify a runaway trim is when we counter the trim which halts it, and then let go, after which the trim immediately runs agains.

With MCAS you counter the trim which doesnít halt it but runs it in the direction you command it, let go, the trim stays in position. You direct your attention to the airspeed unreliable and stickshaker again. Then after some seconds the trim starts running again.
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Old 11th Mar 2019, 11:46
  #335 (permalink)  
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Originally Posted by log0008 View Post
Where will the boxes be read? In Washington?

Also NTSB will be busy at the moment, currently JT610, GT3591 and now ET302 all underway and all very significant incidents.
The NTSB has a bigger-than-usual investigative backlog due to nearly all employees not working during the 35-day government shutdown. Some investigations aren't going to get the attention they normally would.
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Old 11th Mar 2019, 12:09
  #336 (permalink)  
 
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Originally Posted by arketip View Post
Yes, but from what I understand, the MCAS does not behave/look like a runaway trim
Sure it does, the trim moves uncommanded. The 737 gives more notification of this than any other aircraft. Yes if you push a trim switch it stops for 5 seconds but itís stll uncommanded trim.
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Old 11th Mar 2019, 12:09
  #337 (permalink)  
 
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Originally Posted by Azgalor View Post
Oh, this different. I was just a bit confused. So you still see that trim is wrong, trim wheels running etc. But the trick is that it comes back again. I though you do not know that it is trim problem.
Erroneous MCAS intervention does not look like runaway trim, it looks like speed trim. Which intervenes so frequently with automatic trimming during routine climbs that a slowly turning trim wheel in that flight phase may very well get unnoticed, especially in a very high workload situation (continuous stickshaker and unreliable airspeed).
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Old 11th Mar 2019, 12:11
  #338 (permalink)  
 
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Originally Posted by arketip View Post
Yes, but from what I understand, the MCAS does not behave/look like a runaway trim
Indeed it does not - MCAS is not continuous, nor does it stop with opposite trim.
... (Note: intermittent trim is normal on every flight - caused by speed trim.)

And a runaway trim does not have a stick shaker blaring.

And the stab-trim cutout switches are upside down.
We are all told about the nefarious holes in the cheese. Well here is a hole in the cheese - emergency switches fitted upside-down - and yet know-alls come onto this forum and defend one of the holes in the cheese - perhaps the very hole that might have saved the day, had it been plugged...!

Silver

Last edited by silverstrata; 11th Mar 2019 at 14:08.
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Old 11th Mar 2019, 12:11
  #339 (permalink)  
 
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Both flight recorders retrieved from Ethiopian 737 crash site

Both flight recorders retrieved from Ethiopian 737 crash site

  • 11 March, 2019
  • SOURCE: Flight Dashboard
  • BY: David Kaminski-Morrow
  • London
Recovery personnel have retrieve both flight recorders from the Ethiopian Airlines Boeing 737 Max 8 which crashed shortly after take-off from Addis Ababa on 10 March.

The airline states that personnel have recovered the cockpit-voice and digital flight-data recorder from the crash site.

It reiterates that the carrier has grounded the remainder of its 737 Max fleet pending clarification over the cause of the accident.
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Old 11th Mar 2019, 12:16
  #340 (permalink)  
 
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AoA/Airspeed and MCAS

A lot of speculative thought and I add some....

If MCAS is implicated in this and the Lion accident then it is not just the implementation of this software that needs to be thought through.

Should we not also ask about the quality of the data being received by the system? For Lion we are (reliably?) informed that the accident aircraft had been the subject of erroneous AoA data on at least one previous flight and that this had then resulted in the replacement of the sensor. We have generally assumed from the published evidence that the accident flight ALSO suffered from this issue.

At this point William of Occam scratches his head and is wondering whether there is something else in common which is more likely than two sequential AoA failures.

Last edited by PPRuNe Towers; 12th Mar 2019 at 00:54. Reason: No confirmation of reported radio call
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