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Thread: Aeroflot Superjet 100 fire and evacuation at UUEE

  1. #61
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    Taking the FCC's out of the loop shouldn't result in an uncontrollable aircraft. Unless you don't know how to fly it that way...
    Basically concur EXCEPT they didn't reach up and flip off an FCC switch. A big jolt of lightning did it for them along with who knows what else- the flat-screen TVs? the flaps? Not sure if the training covered exactly that. And if your DC-10 suddenly becomes an MD-11...sometimes folks mess that up in spite of good intentions and training...

    Edit/Acknowledgement- As you say, there's indications that flaps were set. There's also comments that they were going very fast. Was the Airspeed indicator fried (or black?) and they were carrying extra speed because of all the parlour talkers bad mouthing the French pull up experts? Anyway- I can imagine why they might have been fast...and one reason is that they were crappy pilots...fried electronics is another. For now, I give a little more credence to the latter...and you?

    Edit #2:
    ***apocryphal HAL myths***
    Sorry that I am always parroting negative myths about HAL, but I think he often helps out with stability in all three axes...maybe even a slight emphasis on pitch & phugoids and all...
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  2. #62
    Senior Member Evan's Avatar
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    Quote Originally Posted by 3WE View Post
    Sorry that I am always parroting negative myths about HAL, but I think he often helps out with stability in all three axes...maybe even a slight emphasis on pitch & phugoids and all...
    Right, because HAL is an autonomous sentient-being with artificial intelligence who presides over all FBW aircraft in exactly the same way and can make random things happen for no reason.

    The SSJ FCC's on the other hand, have nothing to do with artificial intelligence and do not follow the same sentient-being behaviors of other FBW aircraft laws.

    So, for example, unlike the A320/330/340, the SSJ control law retains full damping functions in direct law. Read carefully:

    Quote Originally Posted by Alexander Dolotovsky, Deputy Chief Constructor for Aerodynamics, SCAC
    Minimum mode, when all PFCU, air-data or inertial-reference input is lost, is close to Airbus's "direct law", but with improved manual handling qualities as the damping is still available in roll, yaw and pitch channels. "There is no envelope protection, but handling qualities are close to normal," says Dolotovsky. He adds that the improved handling in minimum mode was well received by SSJ launch customer Aeroflot, which says that the aircraft's control laws are more acceptable compared with Airbus FBW, which lacks Dutch roll damping in direct law.
    Quote Originally Posted by Alexander Dolotovsky, Deputy Chief Constructor for Aerodynamics, SCAC
    [The control laws written for the original yoke version of the SSJ] are now in the minimum, backup mode. Thanks to these algorithms and the good stability of the aircraft, in the «DIRECT MODE» RRJ reminds our old good Tu-134. I won't tell you a secret if I say that we easily lifted the plane in the air and flew more than three months of test flights (if we count the whole program) using the Direct mode. By the way, some of our pilots like «DIRECT MODE» even more than the «NORMAL», because in the Direct mode the plane does not restrict a pilot and control characteristics differ little. This is also a great achievement, because , for instance, entering the «DIRECT MODE» during the education on A320 is only performed on a simulator and during the flight, while we can perform the whole flight in the «DIRECT MODE» and mid-level trained pilots can still control the plane.
    In fact, this is an entirely Russian HAL:

    All software that controls the electronics is actually created by us. We have developed the complete logic of control laws. This intellectual property was created while we were developing our plane.
    It is also robust:

    In order to "knock out" such a system, it is necessary to destroy more than 70% of computers, which is almost impossible given their heterogeneous hardware and software.
    But the apocryphal myths will continue as long as Stanley Kubrick fans who can't tell their ass from a pocket calculator have anything to say about it.

    Quote Originally Posted by Wikipedia, Aeroflot Flight 1492 / citing Bjorn Fehrm, Leeham News and Analysis
    The bounced landing could be a consequence of the aircraft fly by wire controls reverting to direct mode after the lighting strike, being less damped and more sensitive.
    Hey, who needs research when you're already an expert...

    --------------------------

    Now, I concede that the direct law handling will be somewhat different from the normal law one, so if a crew had no experience flying in direct law, perhaps it played a role. I wouldn't rush to that conclusion however and I think it takes more than some minor handling differences to bounce a plane like that.

  3. #63
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    [...a bunch of stuff including a Wiki quote that FBW often helps with stability and that I shouldn't rush to conclusions (I believe my words were I am curious as to what the final report is regarding this stuff...I don't think I rendered any conclusions...not that words don't matter or anything.)]
    You and LHB having a few?

    Indeed, it is almost Beer:30 in Flyover, America?

    And glad to know that stupid pilot screw ups and bad training are still where your emphasis lies.
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  4. #64
    Senior Member Evan's Avatar
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    Quote Originally Posted by 3WE View Post
    And glad to know that stupid pilot screw ups and bad training are still where your emphasis lies.
    Here we are again. By correcting the assumptions and myths of FBW with the FACTS, I am instantly blaming the pilots.

    My emphasis lies with cutting through the BS.

  5. #65
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    Quote Originally Posted by Evan View Post
    My emphasis lies with cutting through the BS.
    Ok...so please show me where you established that the 100's fly by wire system does not add stability, and that the loss of that stabilizing system is definitely not a potential factor here.
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  6. #66
    Senior Member Evan's Avatar
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    Quote Originally Posted by 3WE View Post
    Ok...so please show me where you established that the 100's fly by wire system does not add stability, and that the loss of that stabilizing system is definitely not a potential factor here.
    I just posted that, under the bold words 'read carefully'.

    [Direct law] is close to Airbus's "direct law", but with improved manual handling qualities as the damping is still available in roll, yaw and pitch channels. "There is no envelope protection, but handling qualities are close to normal," says Dolotovsky.
    Not the black and white answer you seem to be asking for, but enough to counter speculation that SSJ direct law was the primary cause of the bounced landing.

  7. #67
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    Quote Originally Posted by Evan View Post
    ...aaaaaaaaaand what might those be?
    Flankers, Fullbacks, Fulcrums and the like. Russian manufacturers have a rather long history of not being too terribly interested in supporting large fleets of airliners abroad. Even going back to the Yak-40, which at the time of its introduction had NO western competitors and was, at least in some ways, such a forward-looking aircraft that Boeing (!) was interested in a joint venture, the attitude has generally been that it's a game not worth playing. The same has regrettably been the case with engineering support. Consider, for another example, the Tu-154, for which technical support was so poor that non-Soviet users turned to MALEV of Hungary, who at the time had a very advanced tech ops department, for expertise and materials rather than to the manufacturer. When Russian carriers started transitioning to western types, it was almost like the industry was relieved to be able to concentrate on military work.

  8. #68
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    Quote Originally Posted by ATLcrew View Post
    Flankers, Fullbacks, Fulcrums and the like. Russian manufacturers have a rather long history of not being too terribly interested in supporting large fleets of airliners abroad. Even going back to the Yak-40, which at the time of its introduction had NO western competitors and was, at least in some ways, such a forward-looking aircraft that Boeing (!) was interested in a joint venture, the attitude has generally been that it's a game not worth playing. The same has regrettably been the case with engineering support. Consider, for another example, the Tu-154, for which technical support was so poor that non-Soviet users turned to MALEV of Hungary, who at the time had a very advanced tech ops department, for expertise and materials rather than to the manufacturer. When Russian carriers started transitioning to western types, it was almost like the industry was relieved to be able to concentrate on military work.
    Don't you think that's changing? The Chinese are all up in it now. Reviving the commercial airliner industry was a Putin initiative. The Irkut MS-21 is in flight testing using the PW 1400G. There is a lot of consultation and cooperation with western airframers and component suppliers. The days of isolation seem to be over. I agree that they will face an uphill battle in winning over the trust of operators and the public, but they seem to be making some pretty competitive aircraft over there, and if I had to choose between a 737-Max and two MS-21's...

  9. #69
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    Not the black and white answer you seem to be asking for, but enough to counter speculation that SSJ direct law was the primary cause of the bounced landing.
    Regarding reading comprehension, where did I say "primary"?

    I also know that my 172-minustwobodies had 'close to normal handling qualities' as did the Narita MD-11...

    You land it a thousand times and one little bounce...gusty winds, electrically compromised aircraft...
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  10. #70
    Senior Member Evan's Avatar
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    Quote Originally Posted by 3WE View Post
    electrically compromised aircraft...
    How compromised is the question we need answered. The SSJ-100 has zero mechanical control provisions. If ALL of the FCC's were actually 'fried', I don't see how it would have ever made the runway (Not having any actual architectural reference, I assume you need at least one FCC operating in direct law to maintain control). I also assume, based on the information I've already posted, that it is not difficult to control with a single FCC working in direct law. But what else failed, what cascade of failures was involved? Does the SSJ have the equivalent of an ELAC? Did those both fail? Etcetera.

    I highly doubt the bounce was caused by direct law alone, but in combination with other failures (or in combination with pilot error), that's a different story.

    Which gets me back to the most important question in my estimation: is the SSJ inadequately protected against lightning strikes (or was this one improperly maintained)?

  11. #71
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    Quote Originally Posted by Evan View Post
    I highly doubt the bounce was caused by direct law alone, but in combination with other failures (or in combination with pilot error),
    Reading comprehension exercise 1: Recheck thread, looking for references to landing at a high speed and crew performance as factors in the bounces.

    that's a different story....the most important question in my estimation: is the SSJ inadequately protected against lightning strikes
    No, it's not "a different story" it's the same plane in the same crash...There's video of a plane flying along beautifully...engines, wings, all functioning...the pilots seemingly in control. Then it goes boom. It's a different aspect, but it's the same story.

    Concur that lightning tolerance is an important question, but the jury is still out on the order of importance. It could very well be that the pilots messed up and crashed a plane that most people would not have crashed...or it could be a nasty stinking fried airliner that isn't reporting key data and is a little more tricky in the flare and hold off phases...or further a combination...
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  12. #72
    Senior Member Evan's Avatar
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    There's a new video on avherald that shows the very final approach and first touchdown. First, it needs be said that the video is hard to make out in detail due to the skips and low resolution (why are all airport runway cameras from 1985?) It shows that the plane was positioned to land pretty much at the runway threshold, which suggests a good degree of controllability up until then, but then it also appears that the plane is 'porpoising' even before it touches down—some noticeable pitch instability. It also either touches down very lightly or not at all before the first 'bounce' (no tire smoke). The second touchdown is hard but the plane pitches up and lifts off again. The final 'bounce' is very high. You have to wonder why they didn't go around at that point (maybe not physically possible in that pilot-aircraft coupling wild-bronco state). The main gear remains attached until the final touchdown, which looks almost akin to the 1500ft/min rate of the Heathrow 777 crash.

  13. #73
    Senior Member Evan's Avatar
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    FDR results are in.

    - The control law was DIRECT after a partial electrical failure (lightning strike?).

    - The approach was a precision approach on ILS (the aircraft was adequately controllable).

    - Flaps were set as 25°, appropriate for the overweight landing. Vapp was 155kts.

    - The crew received multiple predictive WIND SHEAR alerts but did not go-around.

    - The final pitch occillations just prior to the first touchdown were commanded by the pilot.

    Quote Originally Posted by avherald
    Descending between 1100 and 900 feet the crew received 5 cycles of predictive windshear warnings "Wind Shear ahead, go around!". Descending through 260 feet AGL the aircraft began to deviate below the glide slope, a "GLIDESLOPE" warning occurred, descending between 180 to 40 feet the engine thrust was increased causing the aircraft to accelerate to 164 knots, at 16 feet AGL the speed was 170 KIAS. A Terrain Awareness Warning System aural signal "Retard" occurred, the engine thrust was reduced to idle. At that point the captain began to apply oscillating pitch inputs with increasing amplitude which changed the pitch angle up to +6 and -2 degrees.
    - After the first touchdown the ground spoilers did not deploy. In DIRECT law, they must be extended manually. The crew did not extend them during the landing sequence.

    Quote Originally Posted by avherald
    The aircraft made a "three point" touchdown 900 meters past the runway threshold at 158 KIAS and a vertical load of +2.55G and bounced up to 6 feet AGL. The spoilers did not deploy, in DIRECT MODE they are not permitted to operate automatically and need to be extended manually, however, the spoilers were not manually extended by the crew. 2 seconds after the first touch down the aircraft touched down a second time with the nose gear first at 155 KIAS and +5.85G, the aircraft bounced off again to 18 feet AGL. A third touchdown occurred at 140 KIAS in excess of +5G resulting in the destruction of the construction, a fuel spill and fire.
    The crew received a fire warning from the tail section during the 'slideout' landing but the fire suppression wasn't activated for another 40 seconds.

    So, overall, it looks like gross pilot error (failure to go-around due to windshear alert and destabilized approach on short final). With plenty of contributing factors. Still unclear is whether there was some overriding reason to continue the approach and land immediately. My guess is that there wasn't.

    http://avherald.com/h?article=4c78f3e6&opt=0

  14. #74
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan
    So, overall, it looks like gross pilot error
    “Gross”

    Nah, the plane wasn’t stuck by lightning and compromised...

    The joy of pilot admonishment on display.
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  15. #75
    Senior Member Evan's Avatar
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    Quote Originally Posted by 3WE View Post
    “Gross”

    Nah, the plane wasn’t stuck by lightning and compromised...
    I say it LOOKS like gross pilot error because the approach was absolutely stable down to 1100' AGL, suggesting that the plane was sufficiently controllable (as does all of the research I've done on SSJ direct law behavior), but then after not one, not two, not three, and not four but five WINDSHEAR AHEAD, GO AROUND warnings AND dropping below glideslope AND unstable on speed while attempting to land overweight on a wet runway 24L with 30kt winds from 190° the crew failed to GO-AROUND. The windshear warning alone should be a no-bones-about-it go-around unless there is some overriding reason to continue (i.e. control issues, thrust issues in both engines, fuel emergency or fire). None of those boxes appear to be checked here.

    There's no joy in this 3WE. But the point of crash investigations is to determine what went wrong.

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    Senior Member TeeVee's Avatar
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    3BS: aside from the lightning strike and "partial" electrical failure, what else was not in pilot control? seems like these two screwed just about everything to hell from 260' to where the aircraft stopped...

  17. #77
    Senior Member 3WE's Avatar
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    Quote Originally Posted by TeeVee View Post
    3BS: aside from the lightning strike and "partial" electrical failure, what else was not in pilot control? seems like these two screwed just about everything to hell from 260' to where the aircraft stopped...
    -Faster than normal (BUT PRESCRIBED) approach speed.
    -Significantly reduced (BUT PRESCIBED) flap settings
    (I dunno Bobby, will that affect the handling?)
    -Wind shear (probably unexpected)
    -No automatic spoilers
    -No radio to get wind, altimeter setting, traffic

    There’s 5 and I’m just an ass hat parlor talker.
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  18. #78
    Senior Member Evan's Avatar
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    Quote Originally Posted by 3WE View Post
    -Wind shear (probably unexpected)
    [Blue fornt]Yes, after five predictive windshear warnings, It must have come as a total surprise. [/Blue font].

  19. #79
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    Quote Originally Posted by Evan View Post
    [Blue fornt]Yes, after five predictive windshear warnings, It must have come as a total surprise. [/Blue font].
    Immaterial if the decision was made that we better friggen land the plane because we're not sure if it's safely airworthy or not.

    I'm sure the plane looks totally normal to you from 0 ft AGL and 0 knots on your computer keyboard. I keep hoping the view from 15 knots and 1 ft AGL on the bicycle will be of some value.

    Now how about the other four things I listed?
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  20. #80
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    Quote Originally Posted by 3WE View Post
    Immaterial if the decision was made that we better friggen land the plane because we're not sure if it's safely airworthy or not.

    I'm sure the plane looks totally normal to you from 0 ft AGL and 0 knots on your computer keyboard. I keep hoping the view from 15 knots and 1 ft AGL on the bicycle will be of some value.

    Now how about the other four things I listed?
    -Faster than normal (BUT PRESCRIBED) approach speed.
    Airworthy.

    -Significantly reduced (BUT PRESCIBED) flap settings
    Airworthy.

    -No automatic spoilers
    Airworthy.

    -No radio to get wind, altimeter setting, traffic
    Airworthy.

    I don't see any of those things overriding a windshear alert in those conditions or any of those things preventing a go-around.
    I also see a very stable ILS initial approach that tends to make me think controllability was not a serious issue (although deviating from normal, somewhat).

    Now I'm also saying for the umteenth time that we don't know what else they were dealing with. But there is no mention of anything in the report so far to suggest an immediate landing was necessary.

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