Announcement

Collapse
No announcement yet.

Pakistan plane crash: Jet carrying 107 people crashes into houses near airport

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    ATC recording from before the 1st go-around. The go around is just "going around". No reason, distance or altitude is mentioned.

    They seem to be having (and hiding) problems after the go-around. They were cleared to 3500 but ATC calls asking why they stay at 2000 and they say they will stay at 2000. ATC calls that they are at 1800 and descending and they say "trying to maintain 2000". They were supposed to do another ILS approach but they start turning into a short base without advising ATC (no complain there: aviate, navigate communicate) and only when ATC asks "Are you turning left?" they admit having lost the engines.

    What is this repeated chime at 2:40? (before the go-around)?

    https://www.youtube.com/watch?v=jpJa...MZMH8mKbx2nmQw

    --- 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 ---

    Comment


    • #17
      Originally posted by Gabriel View Post
      Evan, what would the control laws be in a scenario of double engine failure and associated system failures (engine-driven hydro pumps, engine-driven generators)?

      I would guess nothing of this would affect the flight control computers which I assume would be powered by the essential bus and hence keep working even if just on battery, and the same would apply to the sensors, IT communication channels, side-stick, etc... so I don;t see a reason to lose normal law. But that's just a guess.

      Asking because in the video of the previous post the plane seems very stable descending at a high AoA. The fact that the plane doesn't fall out of the sky makes me think that it was not stalled, which in turn makes me think that they were sustainedly pulling up and were limited to alpha-max by the control law.
      It's a good question. You recall that Cactus 1549 had Normal Law protections down to the flare, but they also had engine electrical power. The FCOM indicates that on BAT power or on the RAT generator the pitch law reverts to alternate. So that varies depending on whether or not the engines (or the APU) are still able to supply electrical power (I don't think the RAT was deployed in the Hudson ditching). But my research in actual incidents often seems to depart from the FCOM in these situations. Maybe ATL knows.

      Comment


      • #18
        Evan that's not just dirty engines.


        Click image for larger version

Name:	100783266_2538486203030486_7385014493866098688_o.jpg?_nc_cat=1&_nc_sid=0debeb&_nc_oc=AQko-jeoFpYM7j0q82SJqjlVsVmKBmObaEP4HQE2faMwmv2sWqC6R3QJvd0Iy1A0BxE&_nc_ht=scontent-dfw5-1.xx&oh=13dabe0f1a35e18fb681ac7980e39d1c&oe=5EEDAC91.jpg
Views:	556
Size:	918.7 KB
ID:	1090265

        Click image for larger version

Name:	97941314_2538486129697160_1901733917199695872_o.jpg?_nc_cat=1&_nc_sid=0debeb&_nc_oc=AQmJ_ULHcE0Owq6iq3dhF8CqFypaokvlLSwJm4uTB_igxHzvyTLhGBxBkbzcoAPuIPo&_nc_ht=scontent-dfw5-1.xx&oh=0bf9ab55daf36a95275d66a12e4b9a2c&oe=5EEC69AA.jpg
Views:	562
Size:	922.5 KB
ID:	1090264

        --- 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 ---

        Comment


        • #19
          Here you have the URL to see the photos in full resolution:

          https://scontent-dfw5-1.xx.fbcdn.net...2c&oe=5EEC69AA

          https://scontent-dfw5-1.xx.fbcdn.net...1c&oe=5EEDAC91

          --- 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 ---

          Comment


          • #20
            Originally posted by Gabriel View Post
            Evan that's not just dirty engines.
            I don't think it's just 'dirty engines'. I wonder if it's due to oil leakage. Do you think composites contacting with an asphalt runway would leave those black marks? Do you think they would attempt a gear-up landing without advising ATC? Without holding to work the problem first? Right now my head is leaning toward multiple engine failure due to non-standard maintenance during two months of storage. Preceded by EDP hydraulic issues. Very early blind speculation of course.

            Comment


            • #21
              Originally posted by Gabriel View Post
              They do look kind of shredded on the bottom (could be the low resolution). If this was from ground contact, this is just insane.

              Maybe a gear collapse and they got airborne again?

              Comment


              • #22
                Originally posted by Evan View Post

                I don't think it's just 'dirty engines'. I wonder if it's due to oil leakage. Do you think composites contacting with an asphalt runway would leave those black marks?
                I really have no idea. Perhaps the friction set the composites momentarily on fire?

                Do you think they would attempt a gear-up landing without advising ATC?
                No, I don't think the first landing was gear up. At least not main gear up. You would never attempt a go-around from that.
                That said, there are versions of the nose gear not coming down and you can hear the master warning when the tower clears them to land the first time (i.e. before the go around) which they acknowledge.

                Maybe they touched down, started a go around and retracted the gear too early. Or maybe they started the go-around shortly after landing and didn't add power (like that 777) and the airplane initially climbed, they retracted, but lost speed and started to sink, then they added thrust to recover what they did but not before contacting the ground.

                I don't know how or why, but at this point the possibility of them having contacted the runway with the engines seems increasingly probable.

                --- 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 ---

                Comment


                • #23
                  Originally posted by Gabriel View Post
                  Maybe they touched down, started a go around and retracted the gear too early.
                  I guess this is plausible, but the engine strikes must have been very light, more like engine drags...

                  Or maybe they started the go-around shortly after landing and didn't add power (like that 777) and the airplane initially climbed, they retracted, but lost speed and started to sink, then they added thrust to recover what they did but not before contacting the ground.

                  I don't know how or why, but at this point the possibility of them having contacted the runway with the engines seems increasingly probable.
                  If so, this promises to be interesting. There must be some runway surveillance video.

                  Comment


                  • #24
                    By the way... they were so close to making it to the field (not to the runway). They crashed 1000 to 2000 ft short of the field where the situation would have likely been much more survivable (like the BA 777 at Heathrow)

                    --- 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 ---

                    Comment


                    • #25
                      Originally posted by exswissair View Post
                      Not sure if this was posted before:https://youtu.be/YuXv1e68Pq0
                      Is the landing gear visible in this video? (not that it changes much what may have happened in the first approach / go around / runway contact)

                      --- 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 ---

                      Comment


                      • #26
                        Another crazy hypothesis...

                        They had problems with the nose gear and they went around normally (there are reports of a go around due to problems with the nose gear, but perhaps it was first go-around before a second one where they dragged the engines).
                        They could not fix the issue and they decided to land with the nose gear not down and locked.
                        In their second approach, they thought that they had the gear down but they in fact left them up after the previous troubleshooting.
                        They either deactivated or ignored the several different gear-not-down warnings, because they expected them anyway when approaching with the nose gear not secured down. We can hear the master caution continuous repeating chime in the ATC recording when they receive the landing clearance. Having the gear not down and locked below 750 ft RA seems to be a reason for this warning, which is not cancelled.
                        They were already in the flare when they had a last-second "oh shit" moment realizing that the gear was up (3 red, not just the nose gear). They initiated a last second go-around but didn't manage to avoid contacting the runway with the engines, but they did manage to complete the go around and climb out.
                        The rest is history.

                        --- 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 ---

                        Comment


                        • #27
                          Originally posted by Evan View Post

                          It's a good question. You recall that Cactus 1549 had Normal Law protections down to the flare, but they also had engine electrical power. The FCOM indicates that on BAT power or on the RAT generator the pitch law reverts to alternate. So that varies depending on whether or not the engines (or the APU) are still able to supply electrical power (I don't think the RAT was deployed in the Hudson ditching). But my research in actual incidents often seems to depart from the FCOM in these situations. Maybe ATL knows.
                          Maybe he does. Why don't "we" ask him?

                          Comment


                          • #28
                            Originally posted by Evan View Post

                            This past month it seems that the most incredible story will become the one most widely believed. It's bewildering. It blows my mind how naive people have become.
                            That's been blowing my mind since long before this month.

                            Comment


                            • #29
                              What is unfortunate is so many lives could have been saved if he lined up with 25R. The corner of Model Colony comes in front of 25L. 25R had field.

                              Click image for larger version  Name:	D394B30D-2D87-464D-A299-A8F15A925A3B.png Views:	0 Size:	273.2 KB ID:	1090324

                              Comment


                              • #30
                                Originally posted by Gabriel View Post
                                Another crazy hypothesis...

                                They had problems with the nose gear and they went around normally (there are reports of a go around due to problems with the nose gear, but perhaps it was first go-around before a second one where they dragged the engines).
                                They could not fix the issue and they decided to land with the nose gear not down and locked.
                                In their second approach, they thought that they had the gear down but they in fact left them up after the previous troubleshooting.
                                They either deactivated or ignored the several different gear-not-down warnings, because they expected them anyway when approaching with the nose gear not secured down. We can hear the master caution continuous repeating chime in the ATC recording when they receive the landing clearance. Having the gear not down and locked below 750 ft RA seems to be a reason for this warning, which is not cancelled.
                                They were already in the flare when they had a last-second "oh shit" moment realizing that the gear was up (3 red, not just the nose gear). They initiated a last second go-around but didn't manage to avoid contacting the runway with the engines, but they did manage to complete the go around and climb out.
                                The rest is history.
                                Compelling. If they were working the nose gear problem before the first landing attempt and they were following the L/G GEAR DOWNLOCKED procedure, they would first try cycling the gear and then use the gravity extension crank. That would depressurize the hydraulics, so the doors remain open. In the approach, they would switch off the GPWS (no more alert) and reset the gravity extension crank (to repressurize the system, to prevent gear collapse). If they then aborted that attempt, they might have retracted the gear (though why would they if they were having a gear extension problem?). At that point, because they reset the gravity extension, they would have the gear doors closed as seen in the photo and no too low gear warnings from the GPWS. So, it's plausible, but hard to fathom, that they would erroneously make a second attempt without the gear. I would expect a flare or climb out attitude to result in a tail strike as well but who knows.

                                I think the far more likely theory is that this was a botched manual go-around where they failed to set TOGA thrust and retracted the gear (again, why?) too soon, lost height and skimmed along the runway for a second or two, long enough to cause fatal engine damage but not enough to slow below flight speed. At least there is some partial precedent for this.

                                But still crazy.

                                Comment

                                Working...
                                X