boscomantico wrote:
For the rest, this is just how politics and rulemaking works.
Amen.
The original proposal had (b) in AMC, which is where it should be: “if you don’t feel confident in inventing your own means of compliance with the rule, use this one”. But it got changed by the Member States at EASA Committee. While I can’t say it’s the only factor, one aspect is that AMC is not translated (but the rules are). Thus some states like to see as much as possible in the rules, so it is translated into their native language. Go figure.
But what is the minimum acceptable level of oxygen saturation then?
One commonly suggested level is sea level minus 10 e.g. if you are 97 on the surface then 87 should be the minimum. That is what I aim at with everyone I fly with and it’s been OK.
In fact the O2D2 demand reg achieves it effortlessly for all – provided the person actually breathes through their nose which some can’t if their nose is bunged-up or not working for some other reason (then have to use a mask).
Without oxygen, most people will be around 85 at 10,000 feet…. go figure, as they say… On a long trip, I use it above 8k.
dublinpilot wrote:
I don’t disagree with what you say. But I do think that anyone operating at high altitude should use an oximeter.
Ok. But what is the minimum acceptable level of oxygen saturation then? I think that if you operate at altitudes where you really need oxygen (and use O2), then you should really have one to check that the oxygen system is set and functions correctly.
Xtophe wrote:
You might already know your limit from previous experience. You might already know the first signs of hypoxia from previous experience or high-altitude chamber.
That is a dangerous game to play. Your own limit can change on a daily basis; fatigue, blood sugar levels, viruses etc can all significantly change your ability to absorb oxygen. For sure, we all know the first symptoms, yes? Confusion sits pretty close to the top of the list.
I’m not sure I understand Dave and Peter reservation. We can’t be complaining about EASA and or NAA fo fover-regulation, gold plating, cost of certification, … and at the same time complain when they try to relax rules and give some of the decision to the commander.
If you want to keep simple use b).
If you know yourself and your passengers, use a) . There are plenty of evidence that some people are affected by low oxygen as low as 8000ft but that some people are ok to 15000ft.
You might already know your limit from previous experience. You might already know the first signs of hypoxia from previous experience or high-altitude chamber.
As ofetn the rules is barely enforceable. It’s here to make you think and for prosecutor to have something to fall back to if someone take the piss.
Yes, parachuting might have been a factor here. Hadn’t thought about that.
For the rest, this is just how
politics and rulemaking works. In the beginning, there was b), which was very limiting for operators and pilots. Hence they “pulled” some more to limit the damage, and the result is the above, which on the one hand makes it OK for pilots and operators and on the other hands doesn’t make other people lose their face, since b) is still there. 
Personally, I am happy that a) came along, since otherwise, most of my flights would have been in breach of the regulation (standard cruise is FL100 for me, often without oxygen on board if the weather is good). On the other hand, such “bungee paragraphs”, as I call them, aren’t all that great, since they leave room for interpretation which might just as well turn out to be a negative thing in case of some litigation. It is also hard to teach from an instructing standpoint, as one just can’t give enquiring students a clear, simple and short answer.
could the “stupidity” have been caused by hypoxia at a level that would normally be considered “safe”?
Off hand, I can think of two cases, both of which involved a clear disregard of the possibility of hypoxia. Both were very lucky to survive and both probably read EuroGA
Oh I just love EASA-speak and so called work-arounds. As a pilot in command, I will tell myself that it is near impossible for me to ascertain the requirements of sub-para a (even with oximeters taped to all on board) and will therefore automatically revert to sub-para b.
I too don’t understand such a provision. If one was paranoid then it would look like a crude attempt at entrapment, via clearly inevitable noncompliance! I think it is probably the result of considering parachuting schools who drop from say 15k and don’t use oxygen because the people are (?) fit and because they spend so little time at that altitude. Cannulas are not hygienic unless you discard them after use, which is not practical for such ops.
huv wrote:
NCO.OP.190 Use of supplemental oxygen
(a) The pilot-in-command shall ensure that he/she and flight crew members engaged in
performing duties essential to the safe operation of an aircraft in flight use supplemental
oxygen continuously whenever he/she determines that at the altitude of the intended flight
the lack of oxygen might result in impairment of the faculties of crew members, and shall
ensure that supplemental oxygen is available to passengers when lack of oxygen might
harmfully affect passengers.
(b) In any other case when the pilot-in-command cannot determine how the lack of oxygen
might affect all occupants on board, he/she shall ensure that:
(1) all crew members engaged in performing duties essential to the safe operation of an
aircraft in flight use supplemental oxygen for any period in excess of 30 minutes when the
pressure altitude in the the passenger compartment will be between 10 000 ft and 13 000 ft;
and
(2) all occupants use supplemental oxygen for any period that the pressure altitude in the the
passenger compartment will be above 13 000 ft.
Oh I just love EASA-speak and so called work-arounds. As a pilot in command, I will tell myself that it is near impossible for me to ascertain the requirements of sub-para a (even with oximeters taped to all on board) and will therefore automatically revert to sub-para b.
Peter wrote:
utter pilot stupidity
I don’t know about them, but could the “stupidity” have been caused by hypoxia at a level that would normally be considered “safe”?
You need one which velcroes onto the finger. They are pricey.
The oxygen related accidents in the USA that I know of were cases of utter pilot stupidity, like the famous TB20 one over the mountains.
