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Thread: Breaking news: Ethiopian Airlines flight has crashed on way to Nairobi

  1. #681
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Schwartz View Post
    This article is quite interesting and it explains one theory of why they only briefly thumbed the switches near the end.

    https://leehamnews.com/2019/04/05/bj...irst-analysis/



    I think the two key parts are that he claims in an overspeed state, trim adjustments are made very carefully, and the second point is that the MCAS trim is extremely aggressive and fast. By the time it kicked in, there were only seconds before it was nearly impossible to recover from even at that altitude.
    I am not buying it, at least yet. Several seconds after the MCAS ENDED its last activation they were pulling harder than ever on the yoke and were still at positive Gs. Besides, the MCAS is not super aggressive against a sluggish thumb switch action. Yes, it is faster, but they had 5 seconds of no thumb switch activity (with them still pulling up very hard) and they could have used it at any point before or after that. As soon as the MCAS started to apply nose-down trim would have been a good moment. The force on the stick were increasing, the nose was starting to drop and the Gs were reducing. What other indication you need that you need help pulling up?

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  2. #682
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    About 25 seconds after flap retraction and 10 seconds after the first MCAS activation, there were around 280kts. Is that going to damage anything? Are they going to be at that speed if they had reduced thrust 10 seconds earlier?

    This isn't normal ops. Something has to give. Shutting down the pitch trim doesn't seem to save the day. Extending the flaps a bit over the placard speed almost cerrtainly will. But only as part of a simple, four-step memory procedure.
    I don't know. First you have to answer the other question: what if the runaway was not due to the MCAS? Then extending some flaps would be meaningless.

    And you say "if they had reduced thrust 10 seconds earlier" (that is by the time of the 1st MCAS activation). Well, why didn't they? Not because they didn't have the instruction to retract the flaps. They didn't reduce thrust even when they were overspending straight into the ground.

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  3. #683
    Senior Member LH-B744's Avatar
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    Quote Originally Posted by Evan View Post
    About 25 seconds after flap retraction and 10 seconds after the first MCAS activation, there were around 280kts. Is that going to damage anything? Are they going to be at that speed if they had reduced thrust 10 seconds earlier?

    This isn't normal ops. Something has to give. Shutting down the pitch trim doesn't seem to save the day. Extending the flaps a bit over the placard speed almost cerrtainly will. But only as part of a simple, four-step memory procedure.
    God saved the FDR, and somebody has found it. And we are lucky aren't we. Otherwise this discussion might also have reached 685 entries. Incredible. But not yet with so many detail, only a few weeks after it happened.

    Are you trying to go through the t/o and climb procedures of a 737 Max without really sitting in the cockpit? I'd assume that's not easy.

    As far as I know it from a quite good Boeing simulator (Randazzo), with 280 KIAS nothing should break into pieces on board a Boeing jet, not by far. Not without flaps.

    My question for this forum entry #686 was, what was the state of the autopilot. And I've found a good source who says 'off' as an answer.
    ASN report Ethiopian Airlines flight ET #302

    The captain attempted to engage the autopilot twice, but this resulted in two autopilot warnings.
    So. MCAS is by default able to work although a/p is off. That's why somewhere I have seen a switch, or two switches (?), to switch off MCAS. So far it makes sense.
    But. If I could say a wish. In my eyes a/p off and MCAS off should be one switch. And that should be the switches which you use to switch off a/p.

    At least two of these switches can be reached way faster than this tiny MCAS switches somewhere on the cockpit floor. I'm sure.

    Btw, let me warn you, *boring* *spoiler*, this ASN report is rather long and not really helpful, imho. Because it does not mention the word MCAS once.
    LH also has a intercontinental history, the Hamburg - Düsseldorf - Shannon - NYC route, open since June 1st, 1955.
    A/C type: Lockheed Super Constellation.
    The operator on the DUS - NYC route, on the DUS - BKK route, and on the shiny new DUS - LAS nonstop route? EW, one of the dearest LH daughters .

    Aviation enthusiast since more than 30 years. A whole decade here on this platform.

  4. #684
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by LH-B744 View Post
    So. MCAS is by default able to work although a/p is off. That's why somewhere I have seen a switch, or two switches (?), to switch off MCAS. So far it makes sense.
    But. If I could say a wish. In my eyes a/p off and MCAS off should be one switch. And that should be the switches which you use to switch off a/p.

    At least two of these switches can be reached way faster than this tiny MCAS switches somewhere on the cockpit floor. I'm sure.
    The MCAS is armed ONLY in MANUAL FLIGHT with FLAPS RETRACTED.
    If the AP is on, the MCAS is off. If the flaps are not retracted, the MCAS is off.

    And there are no MCAS switch. The report shows how the MCAS kept making trim inputs even after the trim was disconnected with the cutout switches. Only that they trim, turned off in this way, did not respond to the MCAS commands.

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    Quote Originally Posted by Gabriel View Post
    The data shows, separately:
    1) The inputs of the thumb switch
    3) The inputs of the automation (without distinguishing whether it was triggered by the AP, the MCAS or the speed trim)
    4) The position of the stabilizer.
    Thanks. Very helpful. Appreciated.

  6. #686
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    I don't know. First you have to answer the other question: what if the runaway was not due to the MCAS? Then extending some flaps would be meaningless.
    The trim suddenly pulls away from you upon flap retraction? That's how you know it's MCAS. Problem continues with flaps retracted? It's not MCAS, so go to the trim cuttoff switches.

    And you say "if they had reduced thrust 10 seconds earlier" (that is by the time of the 1st MCAS activation). Well, why didn't they? Not because they didn't have the instruction to retract the flaps. They didn't reduce thrust even when they were overspending straight into the ground.
    Because they lacked a memory procedure for this. What I'm suggesting is simple enough to be a memory procedure. It serves to quickly stabilize the situation, like a memory procedure.
    I realize memory procedures must be kept to a minimum and only taught for critical situations where loss-of-control is imminent, but this IS such a situation.
    The -Max needs a memory procedure for this.

    It just astounds me that Boeing is not providing this procedure. What am I missing?

  7. #687
    Senior Member 3WE's Avatar
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    Hey Evan...my head almost exploded...

    This sure does sound like"Use broad knowledge and make stuff up on-the-go that violates procedures (like don't extend flaps unless you are at safe speeds to do so)"...I think someone once called it Cowboy improvisation?

    Quote Originally Posted by Evan View Post
    About 25 seconds after flap retraction and 10 seconds after the first MCAS activation, there were around 280kts. Is that going to damage anything? Are they going to be at that speed if they had reduced thrust 10 seconds earlier?

    This isn't normal ops. Something has to give. Shutting down the pitch trim doesn't seem to save the day. Extending the flaps a bit over the placard speed almost cerrtainly will. But only as part of a simple, four-step memory procedure.
    But fortunately, I see the last sentence that your procedure won't work if the pilots come up with it during the heat of the moment, it only works if it's written in ANOTHER type- and situation-specific memory checklist.

    Nevertheless, nice cowboy improvisation from the keyboard at 0 Radalt and 0 Kts.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  8. #688
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    It just astounds me that Boeing is not providing this procedure. What am I missing?
    What your are missing is that it's not that simple.

    Your fix might work- but does it STILL leave you with an airplane that is different from the other 737's and an airplane that one can argue has a nasty, death-trap behavior when the stars align?

    Does it clearly indicate that you screwed the pooch and TeeVee and friends are going to clean up?

    Are there other things woven into the 50 years of 737 Adaptation...I would not be surprised if there are a couple more fairly critical things that are affected by this MCAS stuff...the simple fix, may derail something else...which derails yet another thing...big $ and maybe we should have been kludging up the 757 instead of the 737.

    Get out of the bubble, ride a bike. Even with that beautiful simplicity, $hit goes wrong...My damn bike is always jumping gears on me...
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    I heard a SW pilot saying that his airline bought additional instrumentation on the 737max.
    I found this video that mentions it (note that announcer gets the function of the AOA sensors wrong).
    https://abcnews.go.com/International...ation-61659989

    Sorry if this has been mentioned[ before

  10. #690
    Senior Member Evan's Avatar
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    Some disturbing revelations today in the New York Times:

    - Boeing didn't provide detailed MCAS information to their own test pilots.
    - MCAS was originally only intended to activate at high speeds, but it then became apparent that it was needed at low speeds as well, where a greater pitch rate and angle were needed. Thus the late-inning change to the higher rates.
    - The FAA didn't require their approval for this because they determined that this didn't represent a "critical phase of flight".
    - Approach-to-stall recovery at low altitude isn't a critical phase of flight.

    Fascinating as ever.

    https://www.nytimes.com/2019/04/11/b...-faa-mcas.html

  11. #691
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    Some disturbing revelations today in the New York Times:

    - Boeing didn't provide detailed MCAS information to their own test pilots.
    - MCAS was originally only intended to activate at high speeds, but it then became apparent that it was needed at low speeds as well, where a greater pitch rate and angle were needed. Thus the late-inning change to the higher rates.
    - The FAA didn't require their approval for this because they determined that this didn't represent a "critical phase of flight".
    - Approach-to-stall recovery at low altitude isn't a critical phase of flight.

    Fascinating as ever.

    https://www.nytimes.com/2019/04/11/b...-faa-mcas.html
    Indeed, the comments are fascinating.

    And troubling that the elephant in the room wasn't listed. Did anyone notice that a single sensor failure puts plane into an arguably relentless dive mode while setting off a bunch of other bells and whistles, including making a few primary instrument readings questionable, along with a nice big dose of "what's it doing now?"
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    Senior Member Evan's Avatar
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    Quote Originally Posted by 3WE View Post
    Indeed, the comments are fascinating.

    And troubling that the elephant in the room wasn't listed. Did anyone notice that a single sensor failure puts plane into an arguably relentless dive mode while setting off a bunch of other bells and whistles, including making a few primary instrument readings questionable, along with a nice big dose of "what's it doing now?"
    It appears that they thought an erroneous MCAS activation would be about as risky to flight control as a erroneous toilet flush. Thus, no need for redundancy (I know... I know... but this is what they seemed to have been thinking).

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    It appears that the left AOA sensor vane was sheared off - possibly by a bird strike.
    https://aviationweek.com/commercial-...37ae42a08ae8a1

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    Senior Member 3WE's Avatar
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    Quote Originally Posted by 3WE View Post
    ***including making a few primary instrument readings questionable***
    Somehow I want to claim this as THE critical flaw/final nail/kill-shot. (Maybe not the BIGGEST engineering flaw- but flaw that is just too hard to overcome).

    I absolutely dislike the nose-over behavior (more than one aspect of it), lack of redundancy, and that the trim that seizes up...

    But that really stands in front of broad fundamental #1. I need the good ole instruments to be able to tell the stick shaker and the trim, and whatever else blinking light to go to hell, and park my thumb on the back side of the trim switch and pull up to a nice high-performance climb...
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    Senior Member Evan's Avatar
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    Quote Originally Posted by Highkeas View Post
    It appears that the left AOA sensor vane was sheared off - possibly by a bird strike.
    https://aviationweek.com/commercial-...37ae42a08ae8a1
    That's what I figured. The AoA plot on the FDR shows the probe mirroring the vertical acceleration data, meaning it couldn't have been influenced by the airstream but was still free to turn. Even a bent vane would be somewhat affected by the airstream. A sheared vane wouldn't.

    MIllion-dollar question now is, was it a bird, a plane, or superstupidman?

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    The LA Times (by far not an authority on aviation I know) has posted an article detailing a document Boeing released before the Ethiopian crash that the MAX 8 (this does not include the MAX 7) may be unsuitable for use at high altitude airports (Addis Ababa is higher than Denver and even a few hundred feet higher than Mexico City). Boeing used the argument/fact that the 737-700 and MAX 7 were better suited for airports at high elevations as part of its claims that Bombardier were infringing on their market share in the niche that is the 737-700 and MAX 7. They noted they didn't believe airlines should be using the MAX 8 or 800 at high altitude airports. Indeed this hasn't been a reason pointed to as a cause of the Ethiopian crash but it brings forth yet another damning piece of evidence against the MAX 8 in this particular case. And indeed some of the airspeed data taken from this crash may be indicative of them not throttling down when they should have and would have at an airport in lower elevations, making the plane harder to recover from its stall due to its faster than recommended speed at that point in flight.

    https://www.latimes.com/business/la-...411-story.html

  17. #697
    Senior Member LH-B744's Avatar
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    Quote Originally Posted by Gabriel View Post
    The MCAS is armed ONLY in MANUAL FLIGHT with FLAPS RETRACTED.
    If the AP is on, the MCAS is off. If the flaps are not retracted, the MCAS is off.

    And there are no MCAS switch. The report shows how the MCAS kept making trim inputs even after the trim was disconnected with the cutout switches. Only that they trim, turned off in this way, did not respond to the MCAS commands.
    And there are no MCAS switches.
    Hm. You should explain your point of view to German Television. I am not able to invent such things!

    On serious German News Television, there was a short video which showed... what. Imho the cockpit of a Boeing 737 Max . Do you think one Aviation Enthusiast who works for serious German News Television has constructed a video

    which shows two switches in a Boeing 737 Max Cockpit, which are precisely located, and you should keep in mind, I'm not able to show you the exact position in Randazzo's 737 simulator, because I only own his B744 QotS I fsx ..
    so, which is precisely located, and you probably don't really know how a B744 cockpit looks like... ,

    let's say you take the leftseat, then your right hand is responsible for the throttle quadrant. Then you move your right hand further backwards. In a B744 cockpit then comes a rather big round knob which is the aileron trim knob. Further backwards.

    The last two switches which you are able to reach down there at the cockpit floor. Or let's compare it to a car. The ash tray which sits above the cardan shaft, for seat row #2.

    There, Heinrich Großbongardt, former company spokesman for Cessna Aviation, showed two switches in a B737 Max.

    I don't know if Mr Großbongardt is a jetphotos member, but this topic would be a brilliant occasion to become one.

    I like to repeat that, I have not dreamed this video. It was shown either on ARD or ZDF (serious German News Television), one or two weeks ago.
    LH also has a intercontinental history, the Hamburg - Düsseldorf - Shannon - NYC route, open since June 1st, 1955.
    A/C type: Lockheed Super Constellation.
    The operator on the DUS - NYC route, on the DUS - BKK route, and on the shiny new DUS - LAS nonstop route? EW, one of the dearest LH daughters .

    Aviation enthusiast since more than 30 years. A whole decade here on this platform.

  18. #698
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    Quote Originally Posted by Gabriel View Post
    And there are no MCAS switches.
    Quote Originally Posted by LH-B744 View Post
    Hm. You should explain your point of view to German Television. I am not able to invent such things!
    I bought a German Television, plugged it in, and carefully explained to it that there are no MCAS switches. So we're all good now.

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    Quote Originally Posted by flashcrash View Post
    I bought a German Television, plugged it in, and carefully explained to it that there are no MCAS switches. So we're all good now.
    If it 'ain't broken........ Don't try to mend it !


  20. #700
    Senior Member LH-B744's Avatar
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    Quote Originally Posted by flashcrash View Post
    I bought a German Television, plugged it in, and carefully explained to it that there are no MCAS switches. So we're all good now.


    Ok. And now you only have to explain that to Lutz Marmor (*1954), who is the CEO of the German NDR television and radio stations, and former
    General for the ARD television stations (NDR, WDR, SWR, BR, ....) between 2013 and 2015.



    PS: Let me add one thing. Since airliners dot de appears on top of the other airliners website, I do no longer wonder where on Earth 737 Max pilots are online.
    But how do you explain the difference between the 738 and a 737 Max 8 to somebody who since 1954 thinks that he knows everything about aviation...
    Last edited by LH-B744; 04-11-2019 at 09:59 PM. Reason: Let's explain a Boeing 737-800 cockpit to a banker, e.g. Mr Marmor.
    LH also has a intercontinental history, the Hamburg - Düsseldorf - Shannon - NYC route, open since June 1st, 1955.
    A/C type: Lockheed Super Constellation.
    The operator on the DUS - NYC route, on the DUS - BKK route, and on the shiny new DUS - LAS nonstop route? EW, one of the dearest LH daughters .

    Aviation enthusiast since more than 30 years. A whole decade here on this platform.

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