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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 13th Mar 2019, 04:54
  #901 (permalink)  
 
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Originally Posted by bunk exceeder
So its a stick pusher that pushes the stick. Plain English please.
You mean MCAS?

A stick pusher doesn't move the stab does it?
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Old 13th Mar 2019, 04:57
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I watched Sean Hannity tonight, he was magnificent as usual.
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Old 13th Mar 2019, 04:58
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Originally Posted by acad_l
Only airliner I can think of that turned out to have a stability issue was the BAC-111. But that was found late in the game, not by design, and the remedy apparently worked.
I am not a pilot nor an engineer, just a geek so correct me if I am wrong but there have been systems similar to MCAS to keep planes stable during hand flying. The ones I know of are the LSAS system on the MD11 and the pilon flaps on the MD90. The difference is that they where not relying on a single sensor.
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Old 13th Mar 2019, 05:12
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Originally Posted by Lonewolf_50
By "it" do you mean the MCAS or the autopilot (as an entity that has a bunch of sub-elements). Your point on possible out-of-trim taken on board.
The autopilot.

You'd think a professional crew would have the aircraft trimmed right before turning on the autopilot.

I don't think these two reports, which I take it are from the two crew on one incident, are relative to this accident, but...?

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Old 13th Mar 2019, 05:15
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Originally Posted by Bonzo777
Why did it take so long and 300+ pax and crew deaths for the industry to acknowledge that a 50 years old original design cannot be modified/updated/re-engineered endlessly?
Tell that to Porsche with their 911
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Old 13th Mar 2019, 05:24
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Originally Posted by 12A
Tell that to Porsche with their 911
And I bet there are more than a few 911 owners here.
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Old 13th Mar 2019, 05:26
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Originally Posted by hans brinker
Actually MCAS functioned as it was supposed to in the Lion Air crash, it received a high AOA signal and kept trimmed accordingly. The broken part was the AOA sensor. There's no need to be afraid of computers adding control inputs with the auto pilot off, the 320 does it all the time and has half the hill loss rate of the 737.
The broken part was a MCAS system that reacted to a single faulty input - instead of comparing that input with its partner; deciding there was a discrepancy; and switching itself off.

On second thoughts, the real broken parts were the designers and engineers who thought that MCAS was a good idea. It looks to me like a case of group confirmation bias, were a small cabal decide upon an action, and they have sufficient authority that nobody else will question their wisdom. As someone said above, flight crews have to do CRM every year, so do Boeing engineers do DRM or ERM every year? (design or engineering resource management)

Silver

Last edited by silverstrata; 13th Mar 2019 at 05:52.
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Old 13th Mar 2019, 05:30
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Applying airspace bans to in-flight aircraft nonsensical

By the time a MAX 8 or 9 has made it to cruise, the phase of flight that claimed Lion and ET is long past. And the pax have to land somewhere, preferably within reasonable reach of destination

There is an argument to made for changing the destination to an airport where a positioning flight will present a minimum hazard to people on the ground.
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Old 13th Mar 2019, 05:30
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MCAS is operational with flaps up. Most (if not all) airlines do not start retracting flaps till 3000’ AFE. According to reports, Ethiopian never achieved anything higher than about a 1,000’ (not even close to 3k).

Most opinions on here are probably from media types baiting for info so they can self profess themselves for the cameras. Give it a rest till something concrete comes out from the FDR/CVR etc investigations.
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Old 13th Mar 2019, 05:32
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MCAS- Massachusetts Comprehensive Assessment System.
Or
Mast Cell Activation System if you prefer.
What does it do? Push the stick? Does the poor 200 hr co pilot know what a stick pusher is? Let alone an MCAS that isn’t mentioned anywhere? Perhaps not a true pusher but call it something that isn’t gibberish please. With Colgan, these things might be issues of understanding.



Last edited by bunk exceeder; 13th Mar 2019 at 05:50.
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Old 13th Mar 2019, 05:39
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Originally Posted by 4runner


I worked for a national carrier in Africa for the better part of a decade. We sent our cadets all over the world for initial pilot training, type ratings recurrence etc. our initial batch of pilots were Air Force officers. Said country didn’t have any aircraft in their inventory...out of 4 sent for type rating training, only 1 made it. This wasn’t really their fault. They needed some additional training to successfully complete advanced jet training. We sent 12 an initio pilots to the US to a well known 141 academy in Florida. 1 pilot came back with a commercial certificate out of 12. We then sent a batch to S Afrika. These were successful for the most part as they were sent based on aptitude and not political connections. The last batch, we sent to Ethiopia for an initio. They were gone for nearly 2 years. Their graduation involved much pomp and ceremony. Many photos and vip’s were present. Many delegates came and even ministers and ambassadors attended this major milestone. Eyes rolling. All of these freshly graduated cadets then did type rating training in Ethiopia. This took another 4-6 months. We now had freshly minted, expert super pilots. None of them could fly a 737 and required over 6 months of line training before they were released to fly the line. 2 failed recurrent at a different facility with non Ethiopian instructors. Others were sent to a non Ethiopian facility to redo their types.
you failed, do not blame them!
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Old 13th Mar 2019, 05:41
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Originally Posted by crosscust
MCAS is operational with flaps up. Most (if not all) airlines do not start retracting flaps till 3000’ AFE.
Are you sure about that?
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Old 13th Mar 2019, 05:44
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Old 13th Mar 2019, 05:49
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Originally Posted by FCeng84
. With this in mind, the nose up thrust induced pitching moment generated by the 737MAX engine is not greater than that for a 737NG. In fact, it is probably less as the center line of the larger MAX engine is higher than the center line of the smaller NG engine given their respective attachment geometries.

Hopefully it is now clear that the pitching moment of concern with the 737MAX engines that gives rise to the need for MCAS is related to the aerodynamic impact of the engine cowling location and geometry, not the magnitude nor location of the thrust vector generated by those engines.
Yes, but the 737NG already had a thrust induced pitch problem, as was amply demonstrated by the Bournnemouth incident, where an NG pitched up to 47 degrees - mostly caused by increased thrust when close to the stall. I have no doubt that Boeing had this problem in mind when they chose to implement the MCAS system. (This was sufficiently well known to already be in the simulator software, which would happily pitch you to 90 degrees up if you got too slow with full power applied.)

The problem being that the MCAS solution was ill thought out and badly designed. The system needed multiple inpututs, including airspeed and attitude. It needed greater redundancy, with another AoA sensor. It needed more refined logic, instead of running to full forward trim, which no aircraft should ever do. It needed greater error checking, to disable the system if faults or data discrepancies were detected. And it really needed to act on the elevator and thrust levers, rather than the stab (ie: reducing the thrust when close to the stall, as per the QRH recommendation).

Apart from that, it was a great design....

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Old 13th Mar 2019, 05:54
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Originally Posted by FCeng84
While there is not yet sufficient information to draw a clear link between the ET accident that is the subject of this thread and MCAS I am deeply troubled by the amount of misinformation regarding MCAS that is being spread here. Reluctantly I offer the explanation below without any suggestion that this system contributed to the tragedy in Ethiopia this last weekend. The truth will be revealed by the recorder data and the full investigation. I strongly implore those who do not know MCAS details to stop providing incorrect information here or anywhere else. Posing questions is fine, but please do not state as fact that about which you are not sufficiently knowledgeable.

MCAS Operation Clarification

MCAS is triggered when all of the following are true:
A. Sensed AOA exceeds a flight condition based activation threshold
B. Flaps are fully retracted (i.e., up)
C. Autopilot is not engaged

When triggered, MCAS commands nose down stabilizer as a function of how much AOA has exceeded the activation threshold and the current Mach number. For large exceedence of the MCAS activation AOA threshold, MCAS will command 2.5 degrees of stabilizer at low Mach number but less than 1/3rd of that at cruise Mach number (gradual Mach number based schedule between). For a lesser exceedence of the MCAS activation AOA threshold the size of the stabilizer increment will be proportionally less. MCAS stabilizer command will be stopped immediately upon pilot activation of pitch trim. (Pilot trim input also serves as MCAS reset - see next paragraph.)

Once MCAS has commanded one increment of stabilizer motion, it will not command more until it has been reset. MCAS is reset if any of the following occur:
1. Pilot makes a manual trim command. (MCAS will not re-activate until there have been 5 continuous seconds without pilot trim command.)
2. AOA drops below MCAS activation threshold and MCAS has run stabilizer in the airplane nose up direction taking out the increment of airplane nose down command it inserted earlier.
3. Autopilot is engaged and then disengaged.

Without pilot trim input, MCAS will not run the stab more than one increment (up to 2.5 degrees) unless MCAS is reset via either 2 or 3 above.

Talk of MCAS running the stabilizer for 10 seconds, pausing for 5 seconds, and then running it again repeatedly without pilot trim input are patently incorrect.
So, to cut a long story short if the AOA and/or air speed readings are incorrect its actions are worse than doing nothing.
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Old 13th Mar 2019, 05:55
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Originally Posted by rh2600
If ever you wanted a good example of regulatory capture, the continuum with China sitting at one side champing at the bit to throw at stone at a US company at the first hint of smoke, and the FAA sitting right at the other holding fast while everyone else sees a fire is a pretty great illustration of the effect.
The FAA needs to set their weather radar to "**** Storm". Because that's what is ahead.
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Old 13th Mar 2019, 06:03
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Boeing 777 Certification

re the comments on this thread about FAA’s willingness to allow certification of a software fix to overcome other issues I recall the 777 was certified to fly over water with only 2 engines after computer simulations only. This was despite certifications up to that time requiring real world testing before certification. 737 Max experience might be part of the continuing trend to engineer workarounds.
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Old 13th Mar 2019, 06:03
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In long ago days of “excessive government red-tape” new airliners were assessed and certificated by aviation authorities in each country where they flew. For Boeing aircraft we all now rely on certification by the US Federal Aviation Administration and in turn FAA delegates most analysis and testing to Boeing.

Until recently senior company engineers called ''Designated Engineering Representatives'' assessed compliance on behalf of FAA. Delegation went further on the Boeing 787. It was first airliner approved under a new ''Organisation Designation Authorisation'' (ODA) arrangement, specifically intended to reduce FAA involvement.

Somehow hazardous lithium ion batteries slipped undetected through the new procedures. Several batteries caught fire and the 787 was grounded. Independent National Transportation Safety Board investigators found:
  • “Boeing’s electrical power system safety assessment did not consider the most severe effects of a cell internal short circuit and include requirements to mitigate related risks, and the review of the assessment by Boeing authorized representatives and Federal Aviation Administration certification engineers did not reveal this deficiency."
  • ”Boeing failed to incorporate design requirements in the 787 main and auxiliary power unit battery specification control drawing to mitigate the most severe effects of a cell internal short circuit, and the Federal Aviation Administration failed to uncover this design vulnerability as part of its review and approval of Boeing’s electrical power system certification plan and proposed methods of compliance."
  • "Unclear traceability among the individual special conditions, safety assessment assumptions and rationale, requirements, and proposed methods of compliance for the 787 main and auxiliary power unit battery likely contributed to the Federal Aviation Administration’s failure to identify the need for a thermal runaway certification test.”

737 Max is second aircraft to be certificated under ODA. After two fatal accidents FAA and Boeing claim the aircraft is safe but admit that mandatory design changes are needed to a Maneuvering Characteristics Augmentation System (MCAS) which is unique to the MAX.

In a “Continued Airworthiness Notice to the International Community” FAA says its “oversight activities” include:
  • Boeing’s completion of the flight control system enhancements, which provide reduced reliance on procedures associated with required pilot memory items. The FAA anticipates mandating these design changes by AD no later than April 2019.
  • Design changes include:
  1. · MCAS Activation Enhancements
  2. · MCAS AOA Signal Enhancements
  3. · MCAS Maximum Command Limit

Which confirms Boeing is running the show and almost invites foreign authorities to play safe and ground the Max.

Who’s ever heard of a “CANIC”? Surely a Notice of Proposed Rule Making is required?

Boeing and FAA swept Lionair accident under the carpet but cannot do same with Ethiopian because it’s more reputable and real people (US and UN) were killed; not just Indonesians on an LCC.
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Old 13th Mar 2019, 06:07
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Originally Posted by silverstrata


The broken part was a MCAS system that reacted to a single faulty input - instead of comparing that input with its partner; deciding there was a discrepancy; and switching itself off.

On second thoughts, the real broken parts were the designers and engineers who thought that MCAS was a good idea. It looks to me like a case of group confirmation bias, were a small cabal decide upon an action, and they have sufficient authority that nobody else will question their wisdom. As someone said above, flight crews have to do CRM every year, so do Boeing engineers do DRM or ERM every year? (design or engineering resource management)

Silver

Originally Posted by acad_l
True. But the Airbus planes are stable throughout their flying envelope. The Max alas is not. The FAA should have never allowed a software fix as a remedy for a basic design flaw. And there must have been engineers at Boeing who were very upset of having been overruled by bean counters and MBA types. Admittedly the MCAS as it is today is a remedy (to the symptoms) worse than the disease. But there should never have been an MCAS in the first place, the right thing to do was to redesign the horizontal stabilizer.

Only airliner I can think of that turned out to have a stability issue was the BAC-111. But that was found late in the game, not by design, and the remedy apparently worked.

Don't get me wrong, I totally agree. The 737 should stop at 150 people and 3 hours, (if B wants a bigger plane start building the 757NG.) If you have stretched your plane so far you need an extra telescoping landing gear and higher speeds to prevent a tailstrike, and software trimming because of inherent instability you are doing something wrong. If you implement said band-aid with a single source input and call it a day, you are well on your way to criminal negligence. MCAS should never have been designed, build or approved this way, my post was just a reply to someone who was more scared of software than hardware, and I disagreed with his POV.
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Old 13th Mar 2019, 06:09
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Originally Posted by ReturningVector



And how many times did the pilots save the airplane from the automation?
at least those pilots who saved the previous pk-lqp Dps-cgk lion air won against Mcas accident, without knowing Mcas even existed and stick shaker blaring all along flight.
as a pax, are these pilots that could handle this situation are rare or not ?
if not then Boeing should really re examined their mcas, and aoa parts should be on MEL.
But could whole AOA system tested on ground ?

Last edited by Realbabilu; 13th Mar 2019 at 07:41.
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