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Southwest 737-300 Emergency Landing After Fuselage Tears Open

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  • #46
    Originally posted by Curtis Malone View Post
    Why not 45deg of bank?
    I fact, I meant to say 45º, like I did in the post after the one you've quoted.
    Why not idle the engines right away?

    Why not extend the spoilers right away?
    Ok and Ok.

    I was focusing more in the fact that instead of pushing down to reduce lift you roll to take the lift out of the vertical and thus reducing it's vertical component with the same effect on building a sink rate but without the nasty (for the passengers) effect of being subject to several seconds of less-than-1G roller coaster feeling.

    In the post after the one you've quoted I've changed and said something like "use the throttles and speedbrakes as needed", because Deadstick mentioned that going to Vmo/Mmo was not a good idea if a structural failure was suspected.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
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    • #47
      Originally posted by Deadstick View Post
      I agree you might want turn make a turn away from traffic below during a rapid descent, but I'm not so sure a 45 degree bank angle would be a great idea. Again, I'm worried (if I'm in the front seat) about some kind of structural failure and I want to get low and slow.
      Ok, you can get all the slow you want. Rolling 45º but NOT pulling up to keep the nose from dropping as you ussually do (because now the nose going down is preciselly what you want) won't put the plane under any additional stress than flying straight and level. It's a fully 1G maneuver.

      I'm very interested in MCM's take on this.
      Yes. Me too.

      --- 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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      • #48
        Originally posted by MCM View Post
        Sure is. However the checklist is not only for an explosive decompression, it is actually for any time the cabin altitude is too high, which is why the situation is specifically addressed.

        Would I be using a 45 degree AoB turn? Absolutely not. Why? Because I want the autopilot engaged. The Boeing depressurisation checklist does not talk about turning off an airway - it is only mentioned in the manoeuvres section, with an "if required". If you're on a very busy airway, and you know there is traffic around, then you would be turning before/as you are descending... its about getting down to your altitude safely. If there is no traffic you know of, then I would be descending straight ahead, and once established in the descent, consider the turn. You still have TCAS, and ATC will attempt to get people out of your way where possible.

        Rapid descents are never performed "that" quickly that you need to be pushing 0g over the top, or rolling rediculous attitudes to get down quicker. Yes, they may save a second or two... but it is far more important to keep the autopilot engaged and conduct a controlled manoeuvre.
        MCM,

        Thanks for your post.
        Obviously what you say doesn't agree with what the other pilot said to me. That's ok for me. Different airlines/manufacturers have different procedures.

        For the record, the idea of rolling 45º was NOT to save a second or two, but prevent a very uncomfortable, sickening and scaring less-than-1G maneuver, with the desirable side effect of turning away.

        You've said "rapid descents are never performed "that" quickly that you need to be pushing 0g over the top". I was not thinking of 0G, more like 0.7G. Probably the passengers in this incident that complained that the plane started to drop violently from the sky, that they thought they were going to die, etc... were not put at 0G or even close.

        Of course, safety comes over comfort, and I prefer that the passengers (me included) think that they are going to die than that thye do. So if rolling 45º is considered not safe (I don't see why), I'm ok with not doing it even if that means more discomfort/scare for the passengers.

        Just out of curiosity, how hard do you think you would push down to establish the descent rate, and what would this descent rate be, in an mergency descent?

        --- 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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        • #49
          Originally posted by guamainiac View Post
          A Corvette stock is capable of 1.0 and a "Z" even more.

          Do you want to be standing during that kind of maneuver? Galley service?
          The cup full of coffee won't drop a drop.
          It's a coordinated 1G maneuver.

          --- 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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          • #50
            Originally posted by lapzdplt View Post
            I also like to know whether a controlled emergency descent due to loss of cabin pressure from 35,000 typically involves significant negative g's.
            No.

            --- 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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            • #51
              I wouldn't push down at all if I could avoid it - I'd allow the autopilot to do it within its normal parameters. It only takes a couple of seconds at tops to be established in a good rate of descent with the autopilot flying the manoeuvre. There are a number of very good reasons to allow the autopilot to fly an emergency descent.

              If I needed to manually do it, I would just slowly pitch down at about the same rate I normally do - allowing for the fact that adrenaline might make that a little quicker .

              I'd take the "we were plummeting" media report with a grain of salt - I've seen those reports for an "emergency descent" before when the descent rate was not dissimilar to a normal descent. Besides which, as you allude to - if there's a dirty great hole in the aeroplane at 35,000', there's a lot more "uncomfortable" going on than a 0.7g manoeuvre. Eardrums bursting, your breath being taken away while you get pulled in your seat towards the hole. Dust flying everywhere, unbelievable noise, screaming...

              I know Gabriel that you are aware of this... just for the edification of others, it is important to remember that an "emergency descent" is not that much different to a normal descent. The only difference is the higher speed and speedbrake use, and that is sometimes done for air traffic control reasons anyway!

              So - you all, as passengers, have quite possibly been in an aircraft doing an "emergency descent" style arrival, and not even known it!

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              • #52
                Originally posted by MCM View Post
                Besides which, as you allude to - if there's a dirty great hole in the aeroplane at 35,000', there's a lot more "uncomfortable" going on than a 0.7g manoeuvre. Eardrums bursting, your breath being taken away while you get pulled in your seat towards the hole. Dust flying everywhere, unbelievable noise, screaming...
                Point made there. I guess that just the yellow masks falling in front of you is enough to scare the hell out of one.

                --- 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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                • #53
                  Originally posted by MCM View Post
                  I'd take the "we were plummeting" media report with a grain of salt - I've seen those reports for an "emergency descent" before when the descent rate was not dissimilar to a normal descent. Besides which, as you allude to - if there's a dirty great hole in the aeroplane at 35,000', there's a lot more "uncomfortable" going on than a 0.7g manoeuvre. Eardrums bursting, your breath being taken away while you get pulled in your seat towards the hole. Dust flying everywhere, unbelievable noise, screaming...
                  So MCM, say you have explosive decompression at 40,000ft. What is your target rate of descent and what is your allowable time to 10,000ft? Do you use V/S or FLCH or VNAV or how do you use the A/P?

                  Do you think there is a tendency for pilots to take over at this point and fly manually?

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                  • #54
                    Originally posted by Evan View Post
                    So MCM, say you have explosive decompression at 40,000ft. What is your target rate of descent and what is your allowable time to 10,000ft?
                    Incidentally I've just read this in a link posted in another thread:

                    Incident: American B752 over Atlantic on Apr 3rd 2011, loss of cabin pressure
                    By Simon Hradecky, created Sunday, Apr 3rd 2011 18:05Z, last updated Sunday, Apr 3rd 2011 18:21Z
                    An American Airlines Boeing 757-200, flight AA-883 from Boston,MA (USA) to Saint Thomas (US Virgin Islands) with 157 people on board, was enroute at FL350 about 150nm southeast of New York,NY (USA) when the crew initiated an emergency descent to 10,000 feet reaching 10,000 feet within 6 minutes (average sink rate 4,166 feet per minute).

                    --- 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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                    • #55
                      Joke time .. timely so Our hero is in pax rattling chop and .. an old one

                      Pilot ... Yada Yada request permission to descend to FL 33 from 37?

                      ATC .... "denied"

                      Pilot ... Yada Yada requests permission to descend to ..

                      ATC ... "denied"

                      Pilot ... Why?

                      ATC ... "noise abatement procedures"

                      Pilot .. "noise abatement on an airway at over 30,000 feet ??

                      ATC ... Yeah, cause when you hit the 747 below you it's going to make lots of noise.
                      Live, from a grassy knoll somewhere near you.

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                      • #56
                        Emergency AD issued 2011-08-51 it mandates Boeing ASB 737-53A1319, eddy current insp of affected areas.

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                        • #57
                          Originally posted by juan23 View Post
                          Emergency AD issued 2011-08-51 it mandates Boeing ASB 737-53A1319, eddy current insp of affected areas.
                          Five days. Not bad. Should've been five minutes, but...

                          So Boeing already had an ASB on this?

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                          • #58
                            G'day Gabriel,

                            No I don't think there is a tendancy for pilots to disconnect and hand fly - certainly not in my airline. The training is done in using the autopilot, with some hand flown to practice it should it be required. Obviously if you have a large gaping hole in the aeroplane it is quite possible the autopilot will have a fit and disconnect of its own accord, in which case I would manually commence the descent and only attempt re-engagement once safely established in a descent.

                            As for the procedure, its pretty simple. Wind down the altitude window, press FLCH, set the speed to what you want it, pull the speedbrake, ensure the thrust levers are at idle.

                            I don't have a target V/S as such, because I know that flying with idle thrust and speedbrakes extended gives me the highest possible V/S for the speed I choose to fly, be it maximum, or existing speed if damaged. I also don't have a maximum time - again, if you've set the configuration for the highest rate of descent possible, there's not a lot more you can do.

                            There is one more trick up your sleeve - using the landing gear - but tends to be reserved for specific occasions and depends on the maximum gear speed/cruise speed of the aeroplane.

                            The key is to get out of the really high altitudes as quicky as possible - although not ideal, at least once you're down in the 20,000's you have time of useful conciousness measured in minutes to tens of mintues rather than seconds.

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                            • #59
                              Thanks MCM, godd post, except for the following:

                              G'day Gabriel,
                              I appreciate you wishing me a good day, but I think you meant "G'day Evan"

                              --- 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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                              • #60
                                Ummmmm, Gabe? Hafa Adai to ya'.
                                Live, from a grassy knoll somewhere near you.

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