Go Back  PPRuNe Forums > Flight Deck Forums > Rumours & News
Reload this Page >

Ethiopian airliner down in Africa

Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots.

Ethiopian airliner down in Africa

Old 12th Mar 2019, 10:30
  #641 (permalink)  
 
Join Date: Jun 2003
Location: surrey
Posts: 14
Likes: 0
Received 0 Likes on 0 Posts
Not a pilot, but an engineer.
Reading this stuff, no doubt in my mind that all these aircraft need to be grounded until comprehensive answer and solution is found.
rzw30 is offline  
Old 12th Mar 2019, 10:33
  #642 (permalink)  
 
Join Date: Mar 2014
Location: Birmingham, UK
Posts: 57
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by rzw30
Not a pilot, but an engineer.
Reading this stuff, no doubt in my mind that all these aircraft need to be grounded until comprehensive answer and solution is found.
I'm pretty surprised that these aircraft are still flying in a lot of countries, like here in the United Kingdom for instance. There needs to be a worldwide ban while the investigation takes place.
AndyJS is offline  
Old 12th Mar 2019, 10:36
  #643 (permalink)  
 
Join Date: Mar 2002
Location: Seat 1A
Posts: 8,532
Received 72 Likes on 41 Posts
Originally Posted by Chesty Morgan
If it gets to the forward stop there's no rush to get to the stab trim cut outs cos it ain't going any further. Fly it away from the ground, might take both of you
Controllable? At say 340KIAS (380 GS)? I very much doubt it.
Capn Bloggs is offline  
Old 12th Mar 2019, 10:38
  #644 (permalink)  
 
Join Date: Sep 2010
Location: by the seaside
Age: 74
Posts: 558
Received 17 Likes on 13 Posts
Obvious that many of you do not understand the different forces involved with the stabiliser and elevator. The elevator only generates a small fraction of the force that the stabiliser generates.
On second and third generation aircraft I flew we had a huge wheel with a white mark, a claxon and a by heart emergency drill to stop a runaway.
You cannot override the stab with the elevator on most aircraft.
blind pew is offline  
Old 12th Mar 2019, 10:39
  #645 (permalink)  
 
Join Date: Jul 2005
Location: France
Posts: 3
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by ifylofd
Where is the manufacturer in all this? Funny how the party line always refers to safety, however those in the industry know and understand all too well the commercial prerogative will normally (covertly) take precedence.
Indeed, with Max sales trailing the NEO by 2900 to 4400 I would be suspicious that Boeing will do everything they can to avoid any suggestion that there is a problem with the MAX.

Boeing enjoyed dominance of this market sector for decades, and the MAX being reduced from dominance to a 40% market share will have the suits worried.
Drjojo is offline  
Old 12th Mar 2019, 10:40
  #646 (permalink)  
 
Join Date: Nov 2011
Location: Japan
Posts: 1,914
Received 125 Likes on 74 Posts
Pinch of salt warning.
Interesting observation by one witness, for further consideration: "Tamrat Abera, a witness who saw the plane go down, told The Associated Press smoke was coming out of the rear and the aircraft rotated twice before hitting the ground."
https://www.aljazeera.com/news/2019/...020507489.html
jolihokistix is online now  
Old 12th Mar 2019, 10:42
  #647 (permalink)  
Gender Faculty Specialist
 
Join Date: Mar 2002
Location: Stop being so stupid, it's Sean's turn
Posts: 1,870
Received 4 Likes on 3 Posts
Originally Posted by Capn Bloggs
Controllable? At say 340KIAS (380 GS)? I very much doubt it.
Well they didn't start at 340kts but they let it get there.



Chesty Morgan is offline  
Old 12th Mar 2019, 10:42
  #648 (permalink)  
 
Join Date: Feb 2017
Location: nl
Posts: 33
Likes: 0
Received 0 Likes on 0 Posts
Maybe it would be good to remind people that aerodynamic forces increase with the square of airspeed. When mis-trimmed airspeed is not your friend.
jan99 is offline  
Old 12th Mar 2019, 10:51
  #649 (permalink)  
 
Join Date: Jul 2009
Location: Asia
Age: 62
Posts: 131
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Capn Bloggs
Controllable? At say 340KIAS (380 GS)? I very much doubt it.
I'm not sure people fully appreciate that the crew only had three minutes to sort this out, that is not a lot of time to process the situation and troubleshoot in any circumstances, but especially so close to the ground at that speed just after take off, no matter what the cause.
bud leon is offline  
Old 12th Mar 2019, 10:58
  #650 (permalink)  
 
Join Date: Feb 2015
Location: Hampshire
Posts: 18
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by jolihokistix
Pinch of salt warning.
Interesting observation by one witness, for further consideration: "Tamrat Abera, a witness who saw the plane go down, told The Associated Press smoke was coming out of the rear and the aircraft rotated twice before hitting the ground."
https://www.aljazeera.com/news/2019/...020507489.html
Having interviewed many folk who have witnessed aircraft accidents, it is not unusual to get the sequence of events in the wrong order or to misinterpret what they are seeing. It is a very traumatic experience for them.
Air Snoop is offline  
Old 12th Mar 2019, 11:03
  #651 (permalink)  
 
Join Date: Mar 2006
Location: Vance, Belgium
Age: 61
Posts: 264
Likes: 0
Received 3 Likes on 2 Posts
Originally Posted by jan99
Maybe it would be good to remind people that aerodynamic forces increase with the square of airspeed. When mis-trimmed airspeed is not your friend.
And if AOA sensor reports a stall, pitch up force on the elevator is multiplied by 4 by EFS.
(I don't imply that this is what happened for the ET accident, but it did happen with the Lion Air accident)
Luc Lion is offline  
Old 12th Mar 2019, 11:03
  #652 (permalink)  
 
Join Date: Jul 2009
Location: Asia
Age: 62
Posts: 131
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Air Snoop
Having interviewed many folk who have witnessed aircraft accidents, it is not unusual to get the sequence of events in the wrong order or to misinterpret what they are seeing. It is a very traumatic experience for them.
And that is often used in court cases to discredit witnesses. It is notable when multiple witnesses describe similar experiences though.
bud leon is offline  
Old 12th Mar 2019, 11:15
  #653 (permalink)  
 
Join Date: Mar 2009
Location: Phoenix, AZ USA
Age: 65
Posts: 0
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Air Snoop
Having interviewed many folk who have witnessed aircraft accidents, it is not unusual to get the sequence of events in the wrong order or to misinterpret what they are seeing. It is a very traumatic experience for them.
I agree completely, the most relevant aspect of the eyewitness accounts is the consistency in believe that the engines sounded wrong. Aural memory is much stronger and more consistently correct then visual memory. That doesn't mean in anyway that anything was actually wrong with the engines just that the sound was different. The airplane was significantly lower than normal and moving at significantly higher speed so the acoustic signature for lack of a better term would be much much different then they would expect and is what they noticed before even acquiring the aircraft visually I'd wager....
SLFinAZ is offline  
Old 12th Mar 2019, 11:19
  #654 (permalink)  
 
Join Date: Jan 2008
Location: uk
Posts: 857
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Chesty Morgan
Something else to ponder is that the 737 is controllable with the trim at either the forward or rear extreme. However, it's a two hands on the column job.
Surely the more pertinent question (at least for Lion Air) is: is it controllable with full forward trim and EFS activated. If it is, is it a two hands on the column job or a four hands on both columns job (and if the latter, which appendage should be used for the trim cut outs / wheels).
infrequentflyer789 is offline  
Old 12th Mar 2019, 11:30
  #655 (permalink)  
 
Join Date: Jan 2001
Location: Australia
Posts: 187
Likes: 0
Received 0 Likes on 0 Posts
The difference between the QF72 incident and the Max8 accidents is that in QF72’s case, it was that its ADR AoA input data was corrupted. As a result they then sent misleading pitch orders.

It was intermittent thus causing even more confusion for the pilots and complicating their ability to identify the root cause.
They also were blessed with a great deal more altitude than the two Max accident crew. In fact one of the QF72 pilots was quoted as saying that his biggest concern during the whole event was what might happen if it occurred again while they were at low altitude.

Nor do I think that there was any trim or HST misbehavior.

Their calm, methodical and disciplined approach to the problem they faced also helped achieve a safe resolution (not that I’m in even the slightest way insinuating the contrary about either of the Max crews). Airbus subsequently issued a bulletin advising pilots how to deal with a similar event.
RAD_ALT_ALIVE is offline  
Old 12th Mar 2019, 11:40
  #656 (permalink)  
 
Join Date: Jan 2013
Location: UK
Age: 63
Posts: 37
Likes: 0
Received 0 Likes on 0 Posts
It is early to be making assumptions about the cause of this crash but it seems there is already good evidence of failures in the design/regulatory/certification process and that these need proper investigation.

I am not a pilot and although I design systems with safety aspects I am not in the aerospace areas. Despite this a key question is why a design change intended as a risk control measure seems to have introduced significant new risks.

On the face of it both the design/development/change control process seems to have failed but also the certification process in considering the impact of a change.

Given what MCAS does the risks of it failing to operate correctly do not need to have been properly consideer and controlled and although there is an element of hindsight it seems quite a stretch to have it vulnerable to a single point failure and with the assumptions that the pilots could control the risk of it failing under all reasonable circumstances and conditiosn without specific training.

There will be a focus on the specific cause of the accident but I would argue more worrying is what looks like a breakdown in the safety/regulatory process with respect to design modifications. Certainly for medical devices (my expertise) statistics suggest that modification of software is one of the largest causes of safety incidents and is therefore an area of focus for regulators.
PiggyBack is offline  
Old 12th Mar 2019, 11:45
  #657 (permalink)  
 
Join Date: Jan 2008
Location: LONDON
Posts: 196
Received 15 Likes on 9 Posts
Is MCAS the sort of system that would previously have been tested with flight trials on a prototype aircraft, but which is now tested using computer modelling?
netstruggler is offline  
Old 12th Mar 2019, 11:49
  #658 (permalink)  
 
Join Date: Mar 2004
Location: Somewhere Over America
Posts: 192
Likes: 0
Received 0 Likes on 0 Posts
If the weather was 60-65 degrees with the field elevation at 7625 then the density altitude was around 9000-9500 at take off.

If they lost an engine then it would be rather sporty.

For bonus points, was it the 200 hr TT F/O's leg?
Halfnut is offline  
Old 12th Mar 2019, 11:53
  #659 (permalink)  
 
Join Date: Apr 2018
Location: Paradise
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
Is it known how many times the MCAS system has activated erroneously on the MAX and been successfully dealt with?
shackson is offline  
Old 12th Mar 2019, 11:57
  #660 (permalink)  
gmx
 
Join Date: Nov 2018
Location: Brisbane
Posts: 25
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Chesty Morgan
Most definitely is. I haven't seen the Lion Air data so I don't know if it ran full forward and stayed there or something else. Obviously startle factor might play a part as well but I'm not sure how startling the trim running slowly forward would be but maybe combined with the stall warning going off wouldn't encourage you to haul back as hard as you can.


I'm only saying that it is controllable at either extreme. Just.

I think its important to remember that the Lion crew kept the aircraft reasonably steady for 6 minutes after MCAS issues presented, continuously and manually counteracting the MCAS nose down events that occurred during that whole time. The crew knew they had a stabilizer runaway b/c they kept using the electric trim to correct it. They kept the aircraft basically level at 5000 feet for that 6 minute duration, until, for the last four MCAS nose down commands, the crew's manual trim responses occur but are just "blipped" (not sufficient to counteract the MCAS input), and assumedly resulted in the stabilizer being full forward.


No one knows why the crew were able to successfully counteract MCAS with manual trim operation for 6 minutes, and then fail to do so for the final 4 MCAS inputs. That is the mystery that we are hoping the CVR will explain.


Lastly, as I understand it, MCAS only dials in *ONE* nose-down increment (2 degrees or whatever it is) and then deactivates itself, until something happens to reactivate MCAS allowing it to dial in another increment. I can't recall all of the crew activities that result in MCAS being reactivated, but I believe one is operation of the manual trim. This is why the last four "blipped" manual trim inputs in the Lion flight result in four unmitigated MCAS nose-down events, because any manual trim input resets MCAS and allows it to reasses the AoA / speed picture and dial in another MCAS trim input.
gmx is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.