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Jeju Air737-800 Crash at MWX (Muan International Airport, South Korea)

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  • #61
    A lot of possible possibilities.

    I'll try to collect some "objective facts" in more-or less chronological order.

    1) Plane was approaching 01 normally
    2) ATC transmitted warning for bird activity
    3) A witness reported seen approaching 01 normally with gear extended (and certainly maybe not 30 or 40 yet but at least a good chunk of flaps extended, since the ground speed was about 154 kts which with almost zero wind and at almost sea level means that the airspeed must have been about that too, which slow enough to absolutely require at least some flaps).
    4) Same witness reported seeing the plane cross a flock of birds and hearing 2 or 3 pops, possibly due to an engine ingesting birds.
    5) Plane announces to ATC that they are going around
    6) Same witness reports that plane started a go around and climbed first, but then was unable to continue climbing.
    7) ADS-B data stops being received when the plane was still in the approach path and at 900 ft.
    8 ) A video shows a plane still on the approach course to 01, with the gear up and some flaps, where the #2 engine (right side) emits a brief flame and a puff of smoke. This must have been after the go around was initiated since the gear was extended before and now it is retraced. It also means that this is a new "event" different from the one the witness reported in point 4).
    9) Crew declares mayday and request to land in RWY 19 (same runway than 01 but opposite direction), and ATC approves.
    10) Plane is seen in the flare of RWY19 coming fast, floating long, and touching down well past the normal touchdown zone still going too fast. Landing gear is up, flaps are totally or mostly up, no spoilers. #2 engine (same one that the previous video shows the surge) is still blowing air (i.e. producing at least some power) during the flare. No evidence to tell if #1 is working or no.
    11) During the skidding the reverser for the #2 engine is seen open.
    12) Plane skids past the end of the runway still at very high speed, skids along 125m of paved stopway plus 125m of grass and slams into a concrete and earth embankment that acts as the base of the ILS localizer antenna.
    13) The impact destroys most of the plane and causes an immediate fireball.
    14) Only the rear of the plane (from the rear doors to the tail) remains relatively intact. From there 2 flight attendants are extracted alive. These are the only survivors.​

    Many scenarios can fit these facts. Things that we don't know:

    a- Was no engine, one engine, or both engines significantly affected due to birds ingestion or other issues?
    b- Did the pilots attempt to shut down any engine, and if so was it one that was still producing useful thrust?
    c- What was the ADS-B data lost on the first approach at 900ft? Did the transponder stop working? If yes, was that due to a loss of electrical power, or maybe by accident when the pilots attempted to squawk 7700? (Note: ADS-B data for other planes in the same airport before the accident was still being received after landing and during taxi). I fear that if this happened as a result of a total electrical failure (except perhaps for the battery-powered essential bus), the CVR and FDR would have stopped recording at that point too so a lot of information of what happened during the second approach and landing would be lost forever.
    ​d- Why didn't the pilot extend the flaps for the second landing? Options are they forgot under stress, they lost all hydraulic and electrical power, they lost hydraulic system A (left side) which powers the flaps and didn't have time and mental bandwidth to deal with the slow and higher workload electric alternate extension, or they elected to leave them up perhaps to reduce drag and extend the glide or be able to fly with deteriorated thrust.
    ​e- Why didn't the pilots extend the landing gear? The landing gear can be extended with the alternate method (purely mechanic) even after a total loss of all hydraulic and electrical power. Forgot? Didn't have time? Or intentional to reduce drag?
    ​f- Did the pilots actuate the reverser of right engine? Or was it a mechanical failure as a consequence of sliding on the engine cowlings?

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
    --- Defend what you say with arguments, not by imposing your credentials ---

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    • #62
      Originally posted by Gabriel View Post
      A lot of possible possibilities.
      10) Plane is seen in the flare of RWY19 coming fast, floating long, and touching down well past the normal touchdown zone still going too fast. Landing gear is up, flaps are totally or mostly up, no spoilers. #2 engine (same one that the previous video shows the surge) is still blowing air (i.e. producing at least some power) during the flare. No evidence to tell if #1 is working or no.
      I disagree with the coming in fast 'objective fact'.
      IMO the speed was perfect for the flap setting as was the flare and touchdown point aiming.
      The reason for the late touchdown is simply due the fact that the 737 descended to a lower height than with the gear extended and you definitely don't want to hit the runway without the gear at a high ROD, hence the late but very smooth touchdown.
      Thrust was obviously insufficient to maintain altitude, hence the decision to land in the opposite direction. Extending the gear, and/or more flaps would have made it impossible to reach the runway and touching down on a runway is the only thing you are trying to achieve. To me it looks like the gear/flap configuration was intentional.
      The lack of spoiler extension, if not for hydraulic reasons could be attributed to task saturation and the relief that the actually made the runway with the crippled 737.
      Furthermore I don't think that anybody had considered the fact that you might run out of runway during a belly landing and of course the unexpected obstacle behind the runway.

      bernt stolle aviation photos on JetPhotos
      Bernt Stolle - Art for Sale | Fine Art America​​

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      • #63
        I fear that if this happened as a result of a total electrical failure (except perhaps for the battery-powered essential bus), the CVR and FDR would have stopped recording at that point too so a lot of information of what happened during the second approach and landing would be lost forever.
        Are you certain about that? I think most modern NG’s have two batteries and a guaranteed 30 minutes of essential electrical power. This, plus the mechanical rigging, allows it to not have a RAT. I would expect low-draw yet fairly important items such as transponder and data recorders to be on the essential bus. It can’t power the EMDP’s so it’s not there for moving flight control surfaces aside from alternate flaps. I did notice that the external beacons do not seem to be working, however. And are there any solid-state short-term data recorders on the NG?

        On the other hand, the Ethiopian 767 that ditched lost CVR when the second engine flamed out.

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        • #64
          Originally posted by bstolle View Post
          I disagree with the coming in fast 'objective fact'.
          IMO the speed was perfect for the flap setting as was the flare and touchdown point aiming.
          The reason for the late touchdown is simply due the fact that the 737 descended to a lower height than with the gear extended and you definitely don't want to hit the runway without the gear at a high ROD, hence the late but very smooth touchdown.
          Thrust was obviously insufficient to maintain altitude, hence the decision to land in the opposite direction. Extending the gear, and/or more flaps would have made it impossible to reach the runway and touching down on a runway is the only thing you are trying to achieve. To me it looks like the gear/flap configuration was intentional.
          The lack of spoiler extension, if not for hydraulic reasons could be attributed to task saturation and the relief that the actually made the runway with the crippled 737.
          Furthermore I don't think that anybody had considered the fact that you might run out of runway during a belly landing and of course the unexpected obstacle behind the runway.
          If in that case, yes, you would be unable to maintain altitude if flaps were deployed at that time so it was intentional.
          Would the runway been attributed to the crash for being to short. I only think the control tower was too focused on getting
          the Boeing 737 to land and forgot about the end of the runway.
          My body lies under the ocean

          My body lies under the sea

          My body lies under the ocean, wrapped in a SB2C!

          B_C

          #Freetodare

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          • #65
            Originally posted by B_C View Post
            Would the runway been attributed to the crash for being to short. I only think the control tower was too focused on getting
            the Boeing 737 to land and forgot about the end of the runway.
            2800m isn't too short and landing in the other direction obviously wasn't an option. Nothing the tower could have done better.
            bernt stolle aviation photos on JetPhotos
            Bernt Stolle - Art for Sale | Fine Art America​​

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            • #66
              was the first go around a correct decision from the pilots? is it normal to continue landing after bird strike at low altitude on the approach?

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              • #67
                Originally posted by thor View Post
                was the first go around a correct decision from the pilots?
                Yes.The reason for the go around wasn't the bird strike itself, but the engine failure it apparently caused.
                bernt stolle aviation photos on JetPhotos
                Bernt Stolle - Art for Sale | Fine Art America​​

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                • #68
                  Originally posted by thor View Post
                  was the first go around a correct decision from the pilots?
                  No. Obviously 179 would still be alive if they continued the approach.

                  Originally posted by thor View Post
                  is it normal to continue landing after bird strike at low altitude on the approach?
                  I would say no, but I believe it is permitted at the discretion of the captain. A bird ingestion into an engine is not just a normal bird strike, but it does not equal engine failure, as we can see #2 engine was providing some thrust prior to landing after the ingestion.

                  Again I'm happy to be told I'm wrong, but please back it up. Thanks!!
                  moving quickly in air

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                  • #69
                    Originally posted by Gabriel View Post
                    Why was the ADS-B data lost on the first approach at 900ft? Did the transponder stop working? If yes, was that due to a loss of electrical power, or maybe by accident when the pilots attempted to squawk 7700? I fear that if this happened as a result of a total electrical failure (except perhaps for the battery-powered essential bus), the CVR and FDR would have stopped recording at that point too so a lot of information of what happened during the second approach and landing would be lost forever.
                    According to my FCOM, continued transponder operation after loss of main electrics depends on the factory order configuration as does the CVR.

                    There is an option that will preserve transponder operation during a loss of both engine-driven generators. IMO this should be required. We don't know if this flight had the option or not.

                    The CVR is designed to keep recording for 5 minutes after the last engine is shut down. Obviously then, it doesn't rely entirely on the engine generators.

                    Newer NG's have something called RIPS (identified by the presence of a RIPS CB in the cockpit). RIPS (Recorder Independent Power Supply) allows the CVR to extend this to 10 minutes, and is part of a new regulation requirement. (I've seen as early as 2005. Recorder Independent Power Supply Mandate was implemented in Canada on May 10, 2023.) IMO, long overdue. We don't know if RIPS was installed on this aircraft, but it is a 2009 build, originally delivered to Ryanair, so perhaps not.

                    In any case, 5 minutes would be sufficient here. The CVR has been successfully read out, so hopefully we will know soon. If the accident was the result of pilot error and/or breakdown of CRM, I would think Boeing might want to get the information out sooner than later, as their 737 brand is damaged enough at this point.

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                    • #70
                      Originally posted by orangehuggy View Post

                      No. Obviously 179 would still be alive if they continued the approach.


                      I would say no, but I believe it is permitted at the discretion of the captain.
                      Sorry, but that's nonsense. You can't change or discard a procedure because it might not work out at a later stage for a completely unrelated reason.

                      Wrong. Why would you discontinue the approach due to a simple birdstrike? A birdstrike doesn't neccessarily mean that an (or more) engine(s) is/are affected.
                      bernt stolle aviation photos on JetPhotos
                      Bernt Stolle - Art for Sale | Fine Art America​​

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                      • #71
                        Originally posted by bstolle View Post
                        Sorry, but that's nonsense. You can't change or discard a procedure because it might not work out at a later stage for a completely unrelated reason.

                        Wrong. Why would you discontinue the approach due to a simple birdstrike? A birdstrike doesn't neccessarily mean that an (or more) engine(s) is/are affected.
                        I don't think it's nonsense, If you hit birds and haven't lost an engine, then go-around. If you didn't have warning of birds in the flightpath and lost an engine for unknown reasons, then maybe go-around. But if you have received an ATC warning of 'flocks of birds' in the fiightpath, get a bird-strike followed by an engine failure and can stabilize the flight path, LAND. By going around you are now flying a single-engine airplane with 170+ souls on board into a known bird-strike environment, where a second engine failure would not be such a remote possibility. Dual engine failures should be expected when both engines share the same environmental threat, such as volcanic ash, or birds. By continuing the landing, even if you lose the second engine and related hydraulics and electrical, you are configured and have the energy to make the runway. Just get it DOWN.

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                        • #72
                          Originally posted by Evan View Post

                          According to my FCOM, continued transponder operation after loss of main electrics depends on the factory order configuration as does the CVR.

                          There is an option that will preserve transponder operation during a loss of both engine-driven generators.
                          "Option" sounds like extra $$$ with zero return on investment, so let me guess... (like the AoA indication "option" that virtually zero airlines "opted" for).

                          The CVR is designed to keep recording for 5 minutes after the last engine is shut down. Obviously then, it doesn't rely entirely on the engine generators.
                          That is confusing and ambiguous. The CVR can be powered by other things that are not the essential bus battery, in addition to the engine generators . Like the APU and external power.
                          Pilots start the APU after landing until connected to external power, or keep one engine running until connected to external power if the APU is not available.
                          My guess is that the APU will continue running for 5 minutes on APU/external power, not essential bus battery, 5 minutes after the last engine is turned off, to preserve the recording (i.e. avoid overwriting it) in case of an extended time on ground under APU or external power.

                          That is, it is an auto switch-off feature rather than an extended recording feature.
                          Again, it's just a guess. But I remember several cases where the CVR and FDR stopped recording the minute engines turned off in flight, sometimes to start recording again when the APU came online.

                          In any event, it seems that at least one engine was still running (even if in a degraded condition), so if one generator kept running then the CVR and FDR should have kept recording all the way to the impact. But then why did the ADS-B data stopped? Maybe the transponder kept working but the ADS-B broadcasting stopped?

                          --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                          --- Defend what you say with arguments, not by imposing your credentials ---

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                          • #73
                            Originally posted by Evan View Post
                            RIPS (Recorder Independent Power Supply).
                            talk about a shit-stupid name for an aircraft system...

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                            • #74
                              I am not sure why the Korean government said that the plane touched down some 1200m down the runway.

                              This picture shows very clearly that the right engine started to skid past 1/2 of the runway, and the left engine a bit farther down. Unless there was some minor skim before that which is not observable in this picture.

                              I did some perspective calculations and my estimation gives that the right engine touched down some 1500 to 1600m / 4900 to 5200ft down the runway,
                              (Runway is 2800m 9200ft, so 1/2 is 1400m / 4600ft. Also, 1/3 is 933m / 3100ft which roughly matches the length of the runway with fixed distance markings on both eds, which are symmetrical in this runway.

                              And also, the aim point is some 400m / 1300ft down the runway and a 900m / 3000ft / last fixed distance marking would be considered the upper limit of a long touch down, and if you didn't touch down by then you should go around (under normal conditions of course, I am not saying that these pilots should have gone around, I don'' t even know if they had sufficient thrust to sustain flight let alone climb).

                              All this to say that this 1500 / 1600m touchdown (that's about 55% of the runway) was really, really long.

                              Attached Files

                              --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                              --- Defend what you say with arguments, not by imposing your credentials ---

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                              • #75
                                Originally posted by Evan View Post
                                If you hit birds and haven't lost an engine, then go-around.

                                If you didn't have warning of birds in the flightpath and lost an engine for unknown reasons, then maybe go-around.

                                But if you have received an ATC warning of 'flocks of birds' in the fiightpath, get a bird-strike followed by an engine failure and can stabilize the flight path, LAND.

                                By going around you are now flying a single-engine airplane with 170+ souls on board into a known bird-strike environment, where a second engine failure would not be such a remote possibility.
                                Why? What would be the reason? This doesn't make any sense.

                                Not maybe. You have to. It's that simple.

                                No, you discontinue the approach and why should an engine failure destabilize the flightpath?

                                I've never heard of multiple birdstrikes which occured on the same flight at different times with different flocks.
                                Furthermore if you start to expect an double engine failure in a birdstrike or icing environment, you should stay at home. There are failures which aren't trained and don't make sense to be trained.


                                bernt stolle aviation photos on JetPhotos
                                Bernt Stolle - Art for Sale | Fine Art America​​

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