Brian CASA NPRM 216 gives some insight (pardon the pun), but doesn't go into the exact causes:
http://rrp.casa.gov.au/nprm/nprm0216and.pdf I believe the effectiveness of the rods in the eye (the bits that provide us with peripheral vision) are very sensitive to the level of oxygen in the blood. Once it starts going down, their effectiveness, and thus that of our peripheral vision is reduced. The rods also provide us with night vision, and so it's equally important to bug smasher pilots who fly at night. One other article that talks about hypoxia and eye physiology is http://www.aoanet.org/eweb/DynamicPage.aspx?site=AOAstage&WebCode=NightVision Cheers Jason On Wed, 25 Aug 2004 00:20:44 +1000, Brian Wade wrote > >Snip from Patrick Barfield > > <As oher people have pointed out, I wouldn't like to be sharing a thermal/wave with this person > > And nor would I! Indeed this is exactly the thought that triggered my initial post on the subject. Nice to have the thread brought back to the key issue so expertly. > Can anyone provide information as to the effect of hypoxia on peripheral vision? > -- > Brian Wade > Personal Computer Concepts > Control SPAM with MailWasher Pro > Uniform Time > http://www.uniformtime.com.au > PO Box 114 INDOOROOPILLY QLD 4068 > Ph: 07 3371 2944 Fax: 07 3870 4103 > > ----- Original Message ----- > From: [EMAIL PROTECTED] > To: Discussion of issues relating to Soaring in Australia. ; Terry Neumann > Sent: Tuesday, August 24, 2004 11:30 PM > Subject: [Aus-soaring] Oxygen safety issues > > Quoting Terry Neumann <[EMAIL PROTECTED]>: > > > > Finally, I can't remember any (perhaps I've been above 9999 feet too > > often), but can someone enlighten me as to just how many accidents or > > fatalities in gliding in Australia have resulted from people going above > > 10,000 feet without oxygen, or alternatively daring to enter the > > statutory (and essentially un-measurable) glider free zone which > > currently exists in respect of each and every cloud? > > > > Stirring mode < OFF> > > > > Regards, > > Terry :-) > > (Past policemen and "enforcer" of gliding rules at various competitions > > since 1971) > > > > I'm not going to weigh in to the policing debate but I do have a few points on high altitude flight safety that some > people seem to have missed by focusing on the policing aspect. > > The greatest danger about hypoxia is the insidious onset which means that a pilot can be incapacitated suddenly > without any warning. Therefore I emphatically disagree with a previous poster who said "if you feel bad, go > down" because you may not realise that you are feeling bad until it is too late by which time you could be > unconscious. In fact, one of the symptoms of hypoxia can be a feeling of euphoria which will delude the pilot into > thinking that everything is fine until he/she passes the time of useful consciousness and is unable to fly the > aircraft. > > For those who say "that couldn't happen to me" consider these examples: > > I have done at least 8 hypobaric chamber runs to experience the symptoms and effects of hypoxia and usually > on each run one indivual out of a group of 8 subjects becomes so incapacitated that they require assistance to > replace their oxygen mask despite extensive prior briefing that everybody must go back on oxygen while they > are still able. If somebody can't even replace their own oxygen mask, how well would they be able to fly an > aircraft? > > While I am unaware of hypoxia fatalities in gliders I remember a Southern Cross Gliding Club Camp in Forbes > about 25 years ago where one pilot chasing gold height was "off with the fairies" when talking on the radio. Either > through good luck or good management he descended to a lower altitude and landed succesfully but afterwards > he couldn't recall the bizarre things that he had been saying on the radio. > > There have been instances of fatalities in the power world and the only similarity between the two fields that I > want to highlight is that the pilot's physiology is the same. So, if these power pilots were unable to recognise that > they were hypoxic and take corrective action, would a glider pilot fare any better? > > I had the unfortunate duty to preside over a RAAF board of enquiry for the loss of a Hornet where the pilot > became hypoxic without being aware of his symptoms (and he had been trained in a hypobaric chamber). He > subsequently lost consciousness and crashed with his aircraft. > > The King air crash in Sep 2000 (See http://www.atsb.gov.au/atsb/media/mrel019.cfm) was also caused by pilot > incapacitation due to hypoxia. If he knew that he was hypoxic, why didn't he go on oxy or descend? > > So why haven't we had any fatalities in gliders if so many people are flying above 10,000? I would hazard a > guess that pilots have been affected to varying degrees but either weren't aware of this or didn't want to admit > that they'd violated a rule. To some degree, the problem in a glider is self-correcting ie if a pilot is being > incapacitated by hypoxia his flying skills would deteriorate to such a point that he would lose the thermal/wave > and then descend to thicker air and recover. As oher people have pointed out, I wouldn't like to be sharing a > thermal/wave with this person. Also, if somebody does "take a nap" for a minute, what would happen to the > glider? Try a simple experiment and let go of the stick for a few minutes if you dare to see what might happen. > Remember at 10,000 AMSL, the TAS is 20% higher than the IAS and VNE/manouvering speeds are calculated on > TAS which means that you are closer to the edge of the flight envelope. > > So to sum up, there are plenty of traps for pilots when flying high without oxygen. The grey area starts when you > have to apply a rule that covers everybody because everybody's physiology is different and I have seen some > individuals last twice as long as others in the hypobaric chamber. I relate it to setting speed limits on the road. > There are some drivers who can drive safely at 150 km/h on the freeway and I have seen other drivers who > shouldn't be allowed to drive on the freeway at all. The big can of worms is where you set the limit and how you > police this limit. Australia has chosen 10,000' as the limit, the US uses 10,000, yet they allow up to 30 minutes > without oxy up to 12,000' (See http://www.risingup.com/fars/info/part135-89- FAR.shtml). > > That's my 2c worth and I will continue to monitor the spirited discussion with interest. > > Patrick Barfield > _______________________________________________ > Aus-soaring mailing list > [EMAIL PROTECTED] > To check or change subscription details, visit: > http://lists.internode.on.net/mailman/listinfo/aus-soaring > _______________________________________________ Aus-soaring mailing list [EMAIL PROTECTED] To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
