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*Another* pilot incapacitated due to pressurization problems?

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  • #16
    Originally posted by Evan View Post
    Which makes me ask, how dangerous is a single engine pressurized a/c?
    I should review the requirements in the FARs.
    I wonder if part 23 airplanes in general, and pressurized turbine singles in particular, are required to:
    - Have a cabin altitude warning.
    - Carry emergency supplemental O2 for the pilot.

    --- 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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    • #17
      The huge problem with hypoxia is the way that it creeps up on you. If the problem is not recognised early enough, while the pilot is still capable of rational thought and actions then any amount of instruction to descend immediately to 10,000 feet by a controller second guessing the problem is unlikely to be acted upon if the effects of hypoxia become established.
      Whilst ATC controllers are not expected to act until a formal emergency is declared it doesn't take a rocket scientist to figure out that the MOST LIKELY REASON for a descent request to an aircraft system malfunction is going to be pressurisation problems especially with a single pilot GA aircraft. It would therefore become essential to get the aircraft down below 12,000 as soon as possible and in any event before hypoxia takes it's full and lethal effect.
      If it 'ain't broken........ Don't try to mend it !

      Comment


      • #18
        Originally posted by brianw999 View Post
        The huge problem with hypoxia is the way that it creeps up on you. If the problem is not recognised early enough, while the pilot is still capable of rational thought and actions then any amount of instruction to descend immediately to 10,000 feet by a controller second guessing the problem is unlikely to be acted upon if the effects of hypoxia become established.
        Whilst ATC controllers are not expected to act until a formal emergency is declared it doesn't take a rocket scientist to figure out that the MOST LIKELY REASON for a descent request to an aircraft system malfunction is going to be pressurisation problems especially with a single pilot GA aircraft. It would therefore become essential to get the aircraft down below 12,000 as soon as possible and in any event before hypoxia takes it's full and lethal effect.
        Well, the little experience that we have with controllers being proactive, shows that pilots that had already pretty much lost their judgement and reasoning abilities, preserve the basic skills to control the plane and the ability to follow simple instructions.

        Of course, there will be a point, even short of actual lose of consciousness, where the mental state will be such that all hopes for the pilot to save himself (even with the help of the ATC) are lost.

        I think that an important thing is to make the pilot establish a controlled descent, preferably on AP. Even if he passes out during the descent, there is a good chance that he will wake up and regain useful consciousness once the plane descended to a more suitable altitude (mid tens), and hopefully before he encounters the ground.

        It has happened that people in sailplanes or paragliders have been caught by a vertical-developing storm and thrown up dozens of thousands of feet. In some cases the plane or paraglider was destroyed, in other cases the pilot died to hypoxia or at least didn't wake up before crashing, but in a couple of cases they woke up during the descent and landed safely.

        There is also a case, in a 727 that suffered rapid decompression, where the captain partially put his mask but did not turn the O2 one because he was busy troubleshooting the situation, and passed out, the flight engineer correctly donned his mask and tried to help the captain by sharing masks, and passed out too. A flight attendant came with portable O2, tried to do the same, and passed out too. Only the junior rookie FO followed the procedures. The first thing he did was don his mask before engaging in any troubleshooting. The second thing he did was initiate an emergency descent. The third thing he did was not try to help his buddies, but in fact by doing this he did help his buddies and all the persons aboard that plane. When the plane was still descending aiming to 10000ft, the captain, flight engineer and flight attendant that were slumped in the cockpit wake up and regained full consciousness.

        And we also have this case that we discussed in the MH370 thread:
        I got this clip from the NATCA Archie Awards, where NATCA gives out awards for the best ATC. http://www.natca.org/mediacenter/Archie2009-Audio-Transcripts.ms...


        Unfortunately there is a part of the recording evidently missing, since they first say to the pilot to descend to 28000, then there is an internal ATC conversation saying that they suspect the pilot has hypoxia, and the next thing we know the plane is at 11000 and the pilots completely recovered.

        ATC very much saved the lives of these guys.

        --- 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
          Originally posted by Gabriel View Post
          I should review the requirements in the FARs.
          I wonder if part 23 airplanes in general, and pressurized turbine singles in particular, are required to:
          - Have a cabin altitude warning.
          - Carry emergency supplemental O2 for the pilot.
          No on the first, yes to the second (14 CFR Part 23.1441(a) and 23.1447(d))

          Comment


          • #20
            Originally posted by brianw999 View Post
            The huge problem with hypoxia is the way that it creeps up on you.
            I don't know if it represents all of the environmental controls/instrumentation, but one thing I notice in the image that Evan posted is there's no cabin altitude gauge.

            I could be wrong, but I suspect "popping ears" are not the most accurate measure of cabin pressure! If that's the only "instrument" you have available, it's easy to see how a slow pressurization failure could occur and go unnoticed.
            Be alert! America needs more lerts.

            Eric Law

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            • #21
              OMG... I was just doing some searching on "TBM-900 cabin pressure" and found this article by obscure aviation writer Les Abend: http://www.cnn.com/2014/09/06/opinio...ash/index.html

              Here's the last paragraph:
              Sad as this outcome was, we can be thankful for small favors. The airplane's sophisticated automation system steered it away from populated areas and a tragedy of even greater proportions.
              Is he seriously trying to imply that "the airplane's sophisticated automation system" was designed to detect pilot incapacitation and direct the plane in such a way that it would crash away from a populated area?

              Near as I can tell, "the airplane's sophisticated automation system" held altitude and heading until the engine stopped due to lack of fuel. IMHO that's about the least sophisticated automation system there is, short of none at all.
              Be alert! America needs more lerts.

              Eric Law

              Comment


              • #22
                Originally posted by elaw View Post
                ***I could be wrong, but I suspect "popping ears" are not the most accurate measure of cabin pressure!***
                Your ears are pretty sensitive when external pressure builds.

                When the external pressure is reducing, your ears equalize much easier- and indeed, if it happens slowly you may not notice.

                Think about your last airline flight....remember anything when you were climbing? I rarely notice.

                On descent, I almost always have to 'yawn' or 'pop' my ears to equalize things.

                Losing cabin pressurization is 'the same' as climbing.
                Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                Comment


                • #23
                  Originally posted by elaw View Post
                  I don't know if it represents all of the environmental controls/instrumentation, but one thing I notice in the image that Evan posted is there's no cabin altitude gauge.

                  I could be wrong, but I suspect "popping ears" are not the most accurate measure of cabin pressure! If that's the only "instrument" you have available, it's easy to see how a slow pressurization failure could occur and go unnoticed.
                  Well it has gone unnoticed in the past. Helios 522 is the most infamous example. In that case the cabin never pressurized because the outflow valve was manually selected open. In this case it might have pressurized and then slowly lost bleed air pressure. Unless there is an alarm, as long as the pressure loss is gradual, hypoxia is going to win.

                  Comment


                  • #24
                    Originally posted by ATLcrew View Post
                    No on the first, yes to the second (14 CFR Part 23.1441(a) and 23.1447(d))
                    Brilliant! I don't see how supplemental O2 is of any use if the pilot never recognizes a pressurization issue. Only alongside a requirement for an alarm does it makes sense.

                    Comment


                    • #25
                      Originally posted by elaw View Post
                      OMG... I was just doing some searching on "TBM-900 cabin pressure" and found this article by obscure aviation writer Les Abend: http://www.cnn.com/2014/09/06/opinio...ash/index.html

                      Here's the last paragraph:
                      Is he seriously trying to imply that "the airplane's sophisticated automation system" was designed to detect pilot incapacitation and direct the plane in such a way that it would crash away from a populated area?

                      Near as I can tell, "the airplane's sophisticated automation system" held altitude and heading until the engine stopped due to lack of fuel. IMHO that's about the least sophisticated automation system there is, short of none at all.
                      Did you note this line from the article?

                      Originally posted by An Obscure Aviation Writer
                      ...The French-made TBM 900...
                      Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                      Comment


                      • #26
                        Originally posted by ATLcrew View Post
                        No on the first, yes to the second (14 CFR Part 23.1441(a) and 23.1447(d))
                        Well, given the "stealth" nature that both pressurization issues and hypoxia can present, that's quite stupid.

                        It's like putting a "cargo hold extinguisher" handle in the cockpit without a "cargo hold fire" alarm.

                        Ok, there must be a cabin altitude indicator, but you can't reasonably expect the pilot to be looking at it all the time in case there is a leak. Especially not since the crew may have only seconds to react and don the masks before loosing useful consciousness.

                        --- 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 Gabriel View Post
                          Well, given the "stealth" nature that both pressurization issues and hypoxia can present, that's quite stupid.
                          And yes, it would have been too stupid, had it been true.

                          §23.841 Pressurized cabins.

                          (b) Pressurized cabins must have at least the following valves, controls, and indicators, for controlling cabin pressure:

                          6) Warning indication at the pilot station to indicate when the safe or preset pressure differential is exceeded and when a cabin pressure altitude of 10,000 feet is exceeded.

                          I admit it, "warning indication" sounds strange. A red line in the cabin altitude dial is a "warning indication"? It certainly is not a "warning" because it doesn't actively "warns" of anything. It's like calling a clock with a red mark at the time you have to wake up an "alarm indication clock".

                          --- 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


                          • #28
                            Originally posted by elaw View Post
                            I don't know if it represents all of the environmental controls/instrumentation, but one thing I notice in the image that Evan posted is there's no cabin altitude gauge.

                            I could be wrong, but I suspect "popping ears" are not the most accurate measure of cabin pressure! If that's the only "instrument" you have available, it's easy to see how a slow pressurization failure could occur and go unnoticed.
                            §23.841 Pressurized cabins.

                            (b) Pressurized cabins must have at least the following valves, controls, and indicators, for controlling cabin pressure:

                            5) Instruments to indicate to the pilot the pressure differential, the cabin pressure altitude, and the rate of change of cabin pressure altitude.

                            --- 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


                            • #29
                              Originally posted by Gabriel View Post
                              And yes, it would have been too stupid, had it been true.

                              §23.841 Pressurized cabins.

                              (b) Pressurized cabins must have at least the following valves, controls, and indicators, for controlling cabin pressure:

                              6) Warning indication at the pilot station to indicate when the safe or preset pressure differential is exceeded and when a cabin pressure altitude of 10,000 feet is exceeded.

                              I admit it, "warning indication" sounds strange. A red line in the cabin altitude dial is a "warning indication"? It certainly is not a "warning" because it doesn't actively "warns" of anything. It's like calling a clock with a red mark at the time you have to wake up an "alarm indication clock".
                              Oh, well. It seems that a red line in the dial would qualify after all as per b-6) (however stupid that is), because issue d clarifies:

                              (d) If certification for operation above 45,000 feet and not more than 51,000 feet is requested—

                              (4) In addition to the cabin altitude indicating means in (b)(6) of this section, an aural or visual signal must be provided to warn the flight crew when the cabin pressure altitude exceeds 10,000 feet.

                              So the real warning ("the sign that warns", according to the above) is not required if the plane is not certified for operation above 45,000ft, which the TBM likely wasn't.

                              --- 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


                              • #30
                                "Popping Ears" will only happen when air pressure increases. It does not occur when air pressure decreases. Any SCUBA divers here will be aware of that. They have to pop their ears on the way down (pressure increase) but not on the way up. It's also the reason why babies cry with pain during an aircraft descent to landing (increasing pressure) but not during an ascent to cruise. They don't know that they need to pop their ears and don't understand what mum and dad tell them.

                                EDIT. I posted this before I noticed that the obscure forumite 3WE ( ) had essentially beaten me to it.
                                Last edited by brianw999; 2014-09-09, 08:55.
                                If it 'ain't broken........ Don't try to mend it !

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