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Helios 522 Redux?

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  • Helios 522 Redux?

    A Jet Airways 737 failed to pressurize due to 'a switch' having been forgotten by the crew. I suspect that the pressurization switch was left in manual after ground testing. If so, it is a repeat of Helios 522, except for the non-fatal outcome. I have to wonder how close this came. Why is there still no alarm (like a configuration warning) to alert pilots once the aircraft exceeds 10,000 ft? Seems like a no-brainer to me.

    https://www.bbc.com/news/world-asia-india-45584300

  • #2
    Originally posted by Evan View Post
    A Jet Airways 737 failed to pressurize due to 'a switch' having been forgotten by the crew. I suspect that the pressurization switch was left in manual after ground testing. If so, it is a repeat of Helios 522, except for the non-fatal outcome. I have to wonder how close this came. Why is there still no alarm (like a configuration warning) to alert pilots once the aircraft exceeds 10,000 ft? Seems like a no-brainer to me.

    https://www.bbc.com/news/world-asia-india-45584300
    There is.

    Comment


    • #3
      https://www.youtube.com/watch?v=gg_flJK85sg

      When I heard about it a few minutes ago, I immediately remembered Helios' disaster.

      It's very scary. I wish we will didn't know such things.

      Comment


      • #4
        Originally posted by Evan View Post
        A Jet Airways 737 failed to pressurize due to 'a switch' having been forgotten by the crew. I suspect that the pressurization switch was left in manual after ground testing. If so, it is a repeat of Helios 522, except for the non-fatal outcome. I have to wonder how close this came. Why is there still no alarm (like a configuration warning) to alert pilots once the aircraft exceeds 10,000 ft? Seems like a no-brainer to me.

        https://www.bbc.com/news/world-asia-india-45584300
        The too-too-too that acts as take-off configuration warning with the aircraft on ground is the cabin altitude warning with the airplane in the air. It was heard in the ATC tapes in the Helios case.
        Then there is another chime and automated PA when the pax mask drop.

        It takes a lot of effort to miss all the cues (and I didn't even mention the cabin altimeter, cabin VSI and diff press gauges).

        --- 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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        • #5
          Some contradiction here:

          The DGCA is following up on reports suspecting the crew forgot to turn on a switch needed for proper cabin pressure control.

          Passengers reported there had been a very sharp drop of cabin pressure causing nose and ear bleeds, the oxygen masks were released.
          http://avherald.com/h?article=4bded8e6&opt=0

          --- 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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          • #6
            By the way, when they say "put the mask over your mouth and nose", and means and, not or.

            --- 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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            • #7
              How can the pilots simply forget! Isn't there a checklist?

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              • #8
                Originally posted by darazarbaf View Post
                How can the pilots simply forget! Isn't there a checklist?
                Checklists are helpful and mitigate the risk, but are not bulletproof.
                People can miss items even when honestly trying to follow a checklist. I have. It is called skipping a line.

                --- 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


                • #9
                  Originally posted by Gabriel View Post
                  Checklists are helpful and mitigate the risk, but are not bulletproof.
                  People can miss items even when honestly trying to follow a checklist. I have. It is called skipping a line.
                  i know i'll catch hell for this, but this why electronic checklists are better. they can be made so that if you do not clear each item, you cannot complete and cannot proceed. they should be built in to EVERY transport category aircraft, and made to prevent takeoff if not completed.

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                  • #10
                    Originally posted by BoeingBobby View Post
                    There is.
                    Sorry, I forgot to use the blue font.

                    Comment


                    • #11
                      Well, if it was blue font than you also understand that not only there is a warning but it served its purpose this time since the crew immediately stopped the climb.

                      A Jet Airways Boeing 737-800 flight 9W-697 departed Mumbai's runway 27 when the passenger oxygen masks were released. The crew stopped the climb at FL110, descended the aircraft to FL100 and returned to Mumbai
                      What I don't understand is why the O2 masks were released.

                      What about an earlier warning? If the cabin vertical speed matches the aircraft vertical speed and it is greater than... I don't know... 1000 fpm, then trigger an alarm. Or if the diff press is zero with the radio-alt greater than 2000ft.

                      --- 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


                      • #12
                        Originally posted by Gabriel View Post
                        Well, if it was blue font than you also understand that not only there is a warning but it served its purpose this time since the crew immediately stopped the climb.
                        That wasn't in the story that broke. The mask deployment, reports of nosebleeds and ear pain and the return didn't seem to indicate that the climb was stopped at a safe altitude.

                        So, why the return? Why not just go "oh, duh" when the alarm sounds, switch to auto, and continue the climb? And why the reported injuries?

                        Comment


                        • #13
                          Originally posted by Evan View Post
                          That wasn't in the story that broke. The mask deployment, reports of nosebleeds and ear pain and the return didn't seem to indicate that the climb was stopped at a safe altitude.

                          So, why the return? Why not just go "oh, duh" when the alarm sounds, switch to auto, and continue the climb? And why the reported injuries?
                          We have 2 contradictions in the AvHerald and others' reports:

                          The report of intense ear pain, ear bleeding and nose bleeding seems consistent with a sudden loss of pressure, not with a gradual reduction in pressure caused by climbing unpressurized as reported.

                          The report of the pilots leveling off at 11000 ft seems inconsistent with the O2 mask deploying.

                          The 2 things that seem to be factual and objective are the injuries and the O2 masks being released. That is consistent with a sudden loss of pressure above 14000 ft.

                          --- 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


                          • #14
                            Originally posted by Gabriel View Post
                            We have 2 contradictions in the AvHerald and others' reports:

                            The report of intense ear pain, ear bleeding and nose bleeding seems consistent with a sudden loss of pressure, not with a gradual reduction in pressure caused by climbing unpressurized as reported.

                            The report of the pilots leveling off at 11000 ft seems inconsistent with the O2 mask deploying.

                            The 2 things that seem to be factual and objective are the injuries and the O2 masks being released. That is consistent with a sudden loss of pressure above 14000 ft.
                            Makes we wonder if event A was the cabin alt warning at 10,000 and event B was later on, due to some improvised solution.

                            Comment


                            • #15
                              Originally posted by Gabriel View Post
                              We have 2 contradictions in the AvHerald and others' reports:

                              The report of intense ear pain, ear bleeding and nose bleeding seems consistent with a sudden loss of pressure, not with a gradual reduction in pressure caused by climbing unpressurized as reported.

                              The report of the pilots leveling off at 11000 ft seems inconsistent with the O2 mask deploying.

                              The 2 things that seem to be factual and objective are the injuries and the O2 masks being released. That is consistent with a sudden loss of pressure above 14000 ft.
                              It could have gone differently. Keep in mind the masks don't necessarily require a *sudden* loss of pressure to drop... a slow increase in cabin altitude will do it to.

                              And the injuries... couldn't they be caused by a sudden *increase* in pressure?

                              So, a possible scenario: pilots accidentally leave pressurization off. Cabin alt. rises as the a/c climbs, and for some reason they miss the altitude warning at 11K. Cabin alt. continues to increase until the masks drop upon reaching 14K. At that point the pilots realize what's going on, turn on pressurization, the a/c suddenly pressurizes and injuries happen.

                              At which point they decide they should return to the airport not because of a technical fault but because of the injured pax.
                              Be alert! America needs more lerts.

                              Eric Law

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