The demise of hypobaric chambers in the RAAF happened in 2001 and coincided with a new approach to hypoxia awareness training as outlined in this Aviation <http://www.defence.gov.au/health/infocentre/journals/ADFHJ_apr04/ADFHealth_ 5_1_03-10.pdf> Medicine paper from the RAAF.
The current approach is called CADO - Combined Altitude and Depleted Oxygen i.e. 10,000' chamber altitude and breathing mixed gas (increased nitrogen and reduced oxygen partial pressure) which gives the same result without the risk of decompression sickness (bends) the risk of which increases above 25,000' altitude. I would argue that the CADO approach gives the same exposure to hypoxia symptoms, however the CADO run doesn't give you the opportunity to replace your mask on your face since you need the mask on to supply the reduced oxygen mix. Looking at the video that started this discussion, it's not always a straightforward thing to don your mask while hypoxic and the most important lesson from the exposure is the insidious onset of hypoxia i.e. while you think you're capable of functioning, your condition will gradually decline to the point where you are incapable of saving yourself i.e. you will die blissfully unaware. There is still a requirement for all RAAF aircrew to do an AVMED refresher every 3 years including the chamber runs which are all done at the Institute of Aviation Medicine at RAAF Edinburgh. I suspect that the reason the gliding community finds it hard to access chamber runs is because now that all other RAAF hypobaric chambers have been decommissioned, you would have to go to Adelaide and with one chamber servicing all RAAF aircrew needs, there may not be any spare capacity to be had. I'll enquire through my contacts whatever happened to the old Passamed (Passenger AVMED) courses that the RAAF used to offer and whether the Institute of AVMED still has the capacity to run these courses. Patrick Barfield -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Anthony Smith Sent: Monday, 9 July 2012 8:44 AM To: 'Discussion of issues relating to Soaring in Australia.' Subject: Re: [Aus-soaring] MORE: Hypoxia / chamber run video >From memory: 4 or 5 were built for the RAAF in around 1944 at the ship works in Newcastle. The original plans were still available at an engineering firm based in Melbourne in the mid 90's. They were powered by a large, double action piston vacuum pump which was based on an 1880's water pump from the Victorian goldfields. The pump had sufficient flow rate to simulate a rapid decompression. They were located at Amberly, Richmond, Pt Cook, Edinburgh and Pearce(?). The Point Cook one was the home of the RAAF school of Aviation Medicine. It was later modified with the addition of a huge vacuum cylinder with a burst disk to simulate an explosive decompression. The vacuum cylinder was pumped down to near zero pressure. When the burst disk was ruptured, all the air in the chamber was sucked into the vacuum cylinder. Spectacular to watch. from the outside. The Point Cook chamber was relocated to Edinburgh in the mid-1990's with the school of Avmed after the closure of Point Cook (EDN then had two chambers - the original chamber was soon mothballed). The original vacuum pump didn't enjoy the new location and soon failed. A new twin scroll pump was installed at great expense. The flow rate achieved was huge and certainly able to seriously injury people inside the chambers unless due care was taken. I am not certain whether the Avmed chamber at EDN was been decommissioned yet. All the others, to the best of my knowledge, were. Some reasons were: - They were never sure about the fatigue life. - People were regularly and sometimes seriously hurt (the bends etc) whilst in the chamber. - There was newer technology around (mixed gas) which was lower risk. From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Monday, 9 July 2012 12:01 AM To: Discussion of issues relating to Soaring in Australia. Subject: Re: [Aus-soaring] MORE: Hypoxia / chamber run video Thanks Rob. That confirms Ian M's post. I wonder if the rationale has been documented, and if so, is the document available to us taxpayers? Can you add some background/detail? Gary ----- Original Message ----- From: Rob Moore <mailto:[email protected]> To: Discussion of issues relating to <mailto:[email protected]> Soaring in Australia. Sent: Monday, July 09, 2012 12:00 AM Subject: Re: [Aus-soaring] MORE: Hypoxia / chamber run video The Chamber is now out of commission Rob Moore On 08/07/2012, at 10:54 PM, <[email protected]> wrote: Hi All, In the "good old days" I did a couple of runs in the RAAF hypobaric chamber at Pt Cook, with another nineteen glider pilots. This chamber was much later relocated to Edinburgh SA airforce base, and as far as I know is still in use there today, by the military. As Ian says, it was an Aviation Medicine Day, with the chamber run being just part of the total experience. The basic scenario involved twenty glider pilots, divided into two groups of ten - 10 being the capacity of the chamber. One group did the chamber run, whilst the other group was given the essential theory - and more.Then we swapped. Yeah, a run to about 23,000' (RAAF normal for ab initios??), is what happened on both occasions. Just like Goldilocks and the 3 bears - not too much and not too little. You are in the danger zone, but there is room to react, if the s**t is hitting the fan. Google "time of useful consciousness" to get an understanding of this subject. The chamber can of course simulate conditions to a much greater height than that - possibly to the upper edge of the atmosphere and beyond: The details are lost in the mists of time, but maybe we just did not ask the right questions for those details (see point 2 below). Apart from these two matters, several things about my two days at Pt Cook come to mind: * The TOTAL professionalism of the RAAF crew running the courses. * Their friendliness, and willingness to share information and further discuss related matters.(We had to wait around for a while at the end of the day to ensure that there were no unexpected negative after-effects resulting from the chamber run.) * The sheer number of RAAF personnel required to conduct and monitor the chamber run - labour intensive for sure. * On my 2nd run, how the team coped with one attendee, who started hyperventilating in the chamber. * Lastly (but by no means least), experiencing the sound (from within the highly insulated chamber), of the run-up of the engines powering the chamber evacuation pumps. I can tell you that the hairs on the back of my neck stood up as those engines wound up to a banshee scream. For what it is worth, I will give you my conclusion from these experiences - there is only one: WHEN IT COMES TO HIGH ALTITUDE FLYING, UNLESS YOU ARE TOTALLY PREPARED, DON'T FUCK WITH DEATH. IF YOU ARE NOT TOTALLY PREPARED, ULTIMATELY YOU WILL LOOSE. Geoff Vincent (who is a member of this forum), and an experienced wave flyer has devoted considerable time to documenting what is required to be "totally prepared", If you want to go wave flying, and are new to the game, I suggest that you get in contact with Geoff - [email protected] Regarding glider pilots using the RAAF hypobaric chamber I offer the following comment. The head of the AAF is a very experienced glider pilot, and I suggest that our new president (Anita), gets in contact with him (Air Marshall Geoff Brown), on this topic.However, I further suggest that you do not hold your breath if you expect a positive outcome. Cheers, Gary ----- Original Message ----- From: Ian Mc Phee <mailto:[email protected]> To: Discussion of issues relating to <mailto:[email protected]> Soaring in Australia. Sent: Sunday, July 08, 2012 6:40 PM Subject: Re: [Aus-soaring] MORE: Hypoxia / chamber run video In the good old days Brad Edwards took a bus load group of us down to RAAF Richmond for an aviation Medicine day and afternoon was a run in decompression chamber and from memory we were taken to 23000ft and no way could any of us complete the counting back by three ie given 100, 97, 94, __,__ There is a well know audio of think F5 pilot having trouble closing his canopy then finally takes off and no mater how hard controllers tried they could not get him to move the Oxy regulators levers forward (giving him 100% oxy) and he just went into subconsciousness to eventually crash. Gather the only serviceable decompression chambers are in NZ now. DAMEs in AUS just experience mixed gasses these days. I think it is a shame at least commercial pilots are not required to do a mixed gas run and that would be more useful than the english test all new pilots must now do to get a PPL and pay a contractor $100 for the 10min test. Ian M On 8 July 2012 09:35, Anthony Smith <[email protected]> wrote: ---- Towards the end, the 'pilot' is unable to put his mask back on, not from lack of motor control or lack of conciousness, but just from not caring. ---- No from not caring. I still cared and wanted to put the mask back on. My experience was the complete inability to get my brain from A to B. I heard the voice say "Number 3, put your mask back on". It took some time to remember that I was 'Number 3' - even though I thought I was fine and was reacting OK. Then there was the fumbling with the mask and the few moments (actually quite a few moments) staring at it whilst I tried to work out which way was up on the mask and how to get it onto my face - even though I thought I was fine and was reacting OK. Once the mask was on, the tunnel vision disappeared (hadn't realized that I had tunnel vision) and all the colours came flooding back (hadn't realized that the world had gone black and white either). I would not have believed anyone afterwards when they told that it took so long for me to think and react, except I saw the second group in the chamber behave in exactly the same way. A remarkable experience and the results are somewhat similar to a long drinking session.
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