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Aviation Forum / Country Specific / Australian Group / September 2008Decompression and business class
Here's a thought that was prompted by JB's incident and the Seven News picture of the A380 business class. If passengers in business class have their heads down when a decompression event occurs, it seems to me entirely possible that they'll lose consciousness (assuming they even wake up) before they can put their masks on. Are the mask tubes long enough that the stewardesses will be able to put masks on the unconscious passengers without having to sit them up first? Sylvia. >Here's a thought that was prompted by JB's incident and the Seven News >picture of the A380 business class. [quoted text clipped - 8 lines] > >Sylvia. rivetting stuff!!!! zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz >> Here's a thought that was prompted by JB's incident and the Seven News >> picture of the A380 business class. [quoted text clipped - 11 lines] > rivetting stuff!!!! > zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz No doubt. Do you know the answer? Sylvia. > >> Here's a thought that was prompted by JB's incident and the Seven News > >> picture of the A380 business class. [quoted text clipped - 17 lines] > > Sylvia. i AM ASSUMING YOU WERE GENUINE with this post . You appear to be making the following assumptions Pax must we very heavy sleepers 1 Decompression will make some additional/unusual noise pax keeps snoozing 2 Crew will probably make an announcment pax keeps sleeping 3 masks dropping will make some noise 4 trim of aircraft will /should alter Nose down crew would probably give them a shake /kick or a good bet to say get up and get your mask on Your question is appropriate as I have no idea how long the tubes are but guess a tad over a meter from the ones I have seen extended Your question has been forwarded to those that know and I shall get back when I have an appropriate answer the only one received so far was to the effect -she is joking right ? That aside Aviation Medicine folks will take your question seriously as it also raises some issues on those pax who may be infirm or less ambulatory than the "average" pax However my take to your is- yes I think so Sylvia a good source of info for you and your type of questions may be when next transiting through Sydney gallop up to the Qantas Museum type thing at Sydney whomever is on duty there is usually a retired cabin type or engineer and they in my experience have always been extraordinarily helpful. ( Ia sked oen chap about some History on Qantas flying boats ) They spent months digging out fantastic stuff and detail and putting me in touch with those in the know on such things HTH Esoteric question for sure. However, the worst question is the one not asked I have been taught >>>> Here's a thought that was prompted by JB's incident and the Seven News >>>> picture of the A380 business class. [quoted text clipped - 27 lines] > crew would probably give them a shake /kick or a good bet to say get > up and get your mask on Some passengers take medication to help them sleep in an environment that isn't otherwise that conducive to it. These medications don't keep a person asleep, but they make them less responsive to stimuli that might otherwise wake them. An explosive decompression would presumably wake everyone up, but not all decompressions are like that. Crew announcements are frequently not that audible at the best of times, and passengers attempting to sleep may have earplugs in, or be wearing noise cancelling headphones. At high altitude there is relatively little time for a person to put on their mask before becoming unconscious. It's far from clear that a passenger would wake up sufficiently in the available time to act appropriately. Nose down trim might not bother someone whose is asleep on a seat laid flat. Also, there are places where an immediate descent is not possible due to terrain. It seems entirely possible that the cabin crew would find themselves faced with a number of people who are unconscious and lying down. > Your question is appropriate as I have no idea how long the tubes > are but guess a tad over a meter from the ones I have seen extended [quoted text clipped - 3 lines] > was > to the effect -she is joking right ? > That aside Aviation Medicine folks will take your question > seriously as it also raises some issues on those pax who may be [quoted text clipped - 13 lines] > Esoteric question for sure. However, the worst question is the one > not asked I have been taught >>>>> Here's a thought that was prompted by JB's incident and the Seven News >>>>> picture of the A380 business class. [quoted text clipped - 80 lines] >> Esoteric question for sure. However, the worst question is the one >> not asked I have been taught Longer is not always better. The longer the tube the greater the chance of it being snagged, getting a knot or becoming a trip hazard. You can't help everybody. :-P "Peter" <someone@microsoft.com> wrote (in part): >Longer is not always better. >The longer the tube the greater the chance of it being snagged, getting a >knot or becoming a trip hazard. Also, you have to pull the tube to turn the oxy on. If it is too long many pax would probably not pull it. >You can't help everybody. > >:-P  SignatureMike Mackenzie (AVCOM Services) Brisbane, AUSTRALIA Remove "XYZ" from the "Reply to" address when responding by email. I presume you are talking about an equivalent event...basically the cabin crew will seat themselves, or squeeze in between some pax seats, and use one of the extra masks available. They won't be walking around looking after passengers until they are told to do so at 14,000 ft. SignatureRead the latest aviation news at www.newsaviation.com > I presume you are talking about an equivalent event...basically the cabin > crew will seat themselves, or squeeze in between some pax seats, and use > one of the extra masks available. They won't be walking around looking > after passengers until they are told to do so at 14,000 ft. Is there any significant risk that someone's going to die from lack of breathable oxygen in a decompression event in the situation, such as with OJK, where the crew are in control and immediately set about 'plummetting' back to 14,000 and individuals don't/can't get a mask on in time to avoid passing out? Are the masks there to keep us alive, or because conscious passengers tend to evacuate the aircraft more quickly? GB SignatureMy friend Steve is an atheist. He has a bumper sticker that reads "Honk if you love Jesus". When someone honks, he gives them the finger. > Is there any significant risk that someone's going to die from lack >of breathable oxygen in a decompression event in the situation, such [quoted text clipped - 3 lines] >or because conscious passengers tend to evacuate the aircraft more >quickly? Actually "did or suffer brain damage..." is the issue. That's one question I asked early on and don't have a good answer to yet. The other one is "How soon does a passed-out person reawaken without supplimental O2 being administered?" Obviously a 100 Kg 60 yo lifelong smoker is going to be different than the 18 yo Olympic marathon winner.... SignatureA host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433 > Is there any significant risk that someone's going to die from lack > of breathable oxygen in a decompression event in the situation, such [quoted text clipped - 3 lines] > or because conscious passengers tend to evacuate the aircraft more > quickly? Good point. I think that oxygen would be there to keep us alive since it could be some time before we're required to egress, and even then it won't necessarily require a critical evacuation (in the recent case I think the pax were on the tarmac for nearly 30 minutes before they disembarked). It's nice to see an intelligent question come from Sylvia's cry for online attention. Have you ever read the book 'Mayday', GB? SignaturePosted at www.Usenet.com.au > Have you ever read the book 'Mayday', GB? Not sure that I have Brian, though the name sounds familiar. Can you give me a bit more info, author, publisher, etc? GB SignatureMy friend Steve is an atheist. He has a bumper sticker that reads "Honk if you love Jesus". When someone honks, he gives them the finger. > Not sure that I have Brian, though the name sounds familiar. Can > you give me a bit more info, author, publisher, etc? Authored by Nelson Demille and Thomas Block (ISBN. 0-7515-2184-1) http://books.google.com/books?id=iPhiGQAACAAJ&dq=mayday A supersonic passenger jet is struck by a missile causing most passengers and the crew to lose consciousness due to the lack of flow from oxygen masks at that high altitude. Only a few remaining passengers survive the explosive decompression without brain damage because they were contained within toilet cubicles or service elevators that retained limited pressure. So basically... a PPL pilot and flight attendant make an attempt to fly the crippled jet back to San Francisco. Of course a large number of passengers and crew turn into violent zombies which makes the task somewhat more complicate than it already is :) Company dispatch then have to make the decision whether to guide the PPL passenger and the jet back to base and suffer the legal consequences of a couple of hundred brain dead passengers, or steer the passenger off course in an attempt to crash it into the ocean and minimise the damage done by insurance. One of the authors is an airline pilot so the attention to detail and fact makes it quite believable - even if the story, aircraft, operation and plot is completely fictional. This thread got me thinking about reading it all over again! If you think you might want to read it I'll gladly send you my copy. SignaturePosted at www.Usenet.com.au > I presume you are talking about an equivalent event...basically the cabin > crew will seat themselves, or squeeze in between some pax seats, and use > one of the extra masks available. They won't be walking around looking > after passengers until they are told to do so at 14,000 ft. That rather impacts on the thinking behind my original question. I was under the impression that the cabin crew immediately donned their portable oxygen masks, and moved around helping those who hadn't got masks on for whatever reason. Sylvia. >I presume you are talking about an equivalent event...basically the cabin > crew will seat themselves, or squeeze in between some pax seats, and use > one of the extra masks available. They won't be walking around looking > after passengers until they are told to do so at 14,000 ft. What if they're over a mountainous region and can't descend for 15 minutes. >What if they're over a mountainous region and can't descend for 15 minutes. What's the longest [in time] route over such a mountain range? Some back of the envelope: Cruise ~500mph. Rapid descent is say 6 minutes. so that's 50 miles. How many points are there that a) Are transited as part of a route b) Are more that 50 miles in all directions from lower elevations? Geography is not my strong point, so I don't really know.... SignatureA host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433 >> What if they're over a mountainous region and can't descend for 15 minutes. > [quoted text clipped - 10 lines] > > Geography is not my strong point, so I don't really know.... Well, there is a large area of Tibet at around 5000 metres, which is crossed by the great-cricle route from London to Bankok, with Mount Everest and other Himalayan mountains positioned disconcertingly between the track and lower terrain in Nepal. Sylvia. >>> What if they're over a mountainous region and can't descend for 15 >>> minutes. [quoted text clipped - 16 lines] > > Sylvia. I've been up the front over the Himalayas, awesome sight. When asked, the pilots said they would just turn right away from flight plan track to get to lower area of terrain in a few minutes. AA >>>> What if they're over a mountainous region and can't descend for 15 >>>> minutes. [quoted text clipped - 21 lines] > to get to lower area of terrain in a few minutes. > AA Yes, from over the top of Everest itself to a safe place to let down looks to be about 60 km, so between three and four minutes. The great circle from London to Bangkok passes somewhat to the north though. Either way, I'd have thought that that was too long for a passenger to be without oxygen at 25,000 feet. Certainly they'd lose consciousness. Sylvia. >Either way, I'd have thought that that was too long for a passenger to >be without oxygen at 25,000 feet. Certainly they'd lose consciousness. > >Sylvia. At least that would quiet the screaming :-) OzOne of the three twins I welcome you to Crackerbox Palace. >> I've been up the front over the Himalayas, awesome sight. When asked, >> the pilots said they would just turn right away from flight plan track [quoted text clipped - 6 lines] > > Sylvia. Well, we were South of Everest by about 10km I'd guess. Back then, you didn't often get to fly great circle over those long distances, especially when flying over Europe with their multitdue of State run Air Nav Service providers. AA Sylvia Else wrote... > Do you know the answer? It's probably the same for all classes where pax are able to get to sleep. > Sylvia Else wrote... > >> Do you know the answer? > > It's probably the same for all classes where pax are able to get to sleep. Other the first class, none of the other classes have seats that will even close to fully recline, so it's unlikely that the tube length would be an issue. Sylvia. > Other the first class, none of the other classes have seats that will > even close to fully recline, so it's unlikely that the tube length would > be an issue. Thats not true, on the A380, the new Business Class seat is now a lie-flat skybed. >> Other the first class, none of the other classes have seats that will >> even close to fully recline, so it's unlikely that the tube length >> would be an issue. > Thats not true, on the A380, the new Business Class seat is now a > lie-flat skybed. The second appearance of the word "other" is not redundant. Try reading my comment in context. Sylvia. Sylvia Else wrote... > Other the first class, none of the other classes have seats that will > even close to fully recline, so it's unlikely that the tube length would > be an issue. I thought that the issue was someone who's asleep when something like this happens going unconcious, rather than whether the tube is long enough to reach the pax. > Sylvia Else wrote... > [quoted text clipped - 5 lines] > happens going unconcious, rather than whether the tube is long enough to reach > the pax. No, the issue was specifically whether the tubes are long enough for the cabin crew to attach masks to passengers without having to sit them up. Since they cannot be lying down in cattle class, the issue doesn't arise. Sylvia. >> Sylvia Else wrote... >> [quoted text clipped - 13 lines] > > Sylvia. The real issue is what is the maximum cabin altitude reached in a "certification" standard decompression. If it is a "non-certification" decompression (as was the JB incident) you are on your own. I can imagine that aircraft manufactures could design a jet transport aircraft which doesn't require pax oxygen for a "certification" decompression (probably have no pax windows). My current understanding is for B747 and similar, a certification decompression is all a/c pacs operating and two pax windows instantaneously removed. During the emergency descent, following a decompression, the aircraft altitude is decreasing (obviously) and the cabin altitude is increasing until they are both equal, then the cabin descends at a rate determined by the aircraft rate of descent and how much air can flow back into the cabin through the holes. Cheers >>> Sylvia Else wrote... >>> [quoted text clipped - 29 lines] > by the aircraft rate of descent and how much air can flow back into the > cabin through the holes. Whether that's the real issue surely rather depends on where ones interests lie (thus defining 'real'). I was more concerned about the lives of the passengers than whether the aircraft can meet its certification requirements. The latter provide a good basis for protecting the former, but that's as far as it goes. Sylvia. >My current understanding is for B747 and similar, a certification >decompression is all a/c pacs operating and two pax windows [quoted text clipped - 5 lines] >by the aircraft rate of descent and how much air can flow back into the >cabin through the holes. From the preliminary report on JB's incident, it appears it took one minute to go from 12.5 psi to 5.25 psi/26000 ft. By then, they'd been decending for only a few seconds, so it's hard to say what the outside air pressure was, but it must have been at least 5.25psi. [Unless we think the packs can produce enough volume to make up for that gaping hole.....] An interesting graph would be outside air pressure vs cabin. There's several fudge factors involved but I assume the data logging has all of them. With 2 windows out, I can't see how repressurization would lag decent; i.e. air could flow in faster than pressure could increase during a controlled decent. But maybe I'm wrong; there is a lot of volume in a 747's skin. SignatureA host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433 >>> Sylvia Else wrote... >>> [quoted text clipped - 29 lines] >cabin through the holes. >Cheers I'd be surprised if many people who were using oxygen through the passenger masks lost consciousness. Smokers, perhaps, and the chronically ill, but most should maintain consciousness if breathing oxygen even if the cabin altitude got to 25,000'. During WWII Charles Lindbergh did experiments simulating bailing out at 40,000' and descending at parachute rates (3,000' per minute) on emergency oxygen. In one of these experiments he removed his oxygen at 25,000, and while noticing slight effects of oxy deprivation passing through 23,000' recorded that he felt fine again by the time he reached 20,000'. On another occasion he removed his oxygen mask at 27,000' on the descent and left it off until they had descended to ground level. He tried breathing the air at 40,000' and found he lasted about four breaths before noticing a "serious" lack of oxygen, and that thhis lasted until 15 or 20 seconds *after* he replaced his oxygen mask due to the time lag in circulation of oxygen fron the lungs to the brain. Given descent rates approaching that of a parachute, reasonable health, and prompt application of the oxygen masks, passing out would seem relatively unlikely. Coop |
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