Ethiopian airliner down in Africa
Join Date: Mar 2014
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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.
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
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.
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.
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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.
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
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
Gender Faculty Specialist
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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.
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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
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
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(I don't imply that this is what happened for the ET accident, but it did happen with the Lion Air accident)
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And that is often used in court cases to discredit witnesses. It is notable when multiple witnesses describe similar experiences though.
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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....
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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).
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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.
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.
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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.
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.
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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?
If they lost an engine then it would be rather sporty.
For bonus points, was it the 200 hr TT F/O's leg?
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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'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.