Gentlemen,
As interesting, educational and nostalgic as this
thread has become let's not lose sight of the
most important element of the hypoxia debate -
that is, PREVENTION! One's deteriorating ability
to recognise symptoms of hypoxia, let alone take
effective corrective action occurs remarkably
quickly and is well and truly the action of last
resort. And don't run away with the idea that
restoration of the oxygen supply immediately
restores the former "clear mind" status quo -
superficially maybe, but your perception and
judgement often remains seriously impaired for
hours. Not unlike dehydration - quick onset but
slow recovery. Thorough pre-flight planning,
having reliable equipment, good physical
condition, good understanding of risks (including
rehearsal of emergency procedures) and having
back-up systems (especially in situations where
the time of useful consciousness may be expressed
in small single digit numbers) are the
fundamental requirements for remaining alive.
Believe me, it's hostile country, with plenty of
traps for the casual or unwary pilot.
Regards,
Geoff V
At 10:23 AM 9/07/2012, Patrick Barfield wrote:
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
<http://www.defence.gov.au/health/infocentre/journals/ADFHJ_apr04/ADFHealth_5_1_03-10.pdf>Aviation
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 doesnt 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, its 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
youre 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. Ill 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 90s.
They were powered by a large, double action
piston vacuum pump which was based on an 1880s
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-1990s 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 didnt
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: <mailto:[email protected]>Rob Moore
To:
<mailto:[email protected]>Discussion
of issues relating to 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,
<<mailto:[email protected]>[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 -
<mailto:[email protected]>[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: <mailto:[email protected]>Ian Mc Phee
To:
<mailto:[email protected]>Discussion
of issues relating to 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
<<mailto:[email protected]>[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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