Presumably using a finger pulse-ox meter and ensuring a reading in excess of 90% would qualify as determining that a given altitude is not harmfully impairing faculties…,
Where does the recommendation of 90% come from (I have heard that several times already?) Is it something “Official”? One of the few places I’ve been able to find something with actual numbers was in this article, in which It would like the FAA requirements correspond to something more like 80s
http://www.flyingmag.com/technique/proficiency/technicalities-hypoxia-your-fingertips
(I don’t know the source of their graph either)
Walter wrote:
But it doesn’t specify mask or canulas?
AFAIK whatever works for you is just fine.
IIRC, 90% is approximately the “natural” level a healthy sea-level dweller achieves around 8-10,000, hence this is a good number to aim for when higher.
Where does the recommendation of 90% come from
Are there any official calibrated certified pulse-ox meters available? If not (as I guess), the 90% cannot be official either. Better to err on the safe side, poor simple me thinks.
The general view over many years is that you should not be more than 10 percentage points below your sea level blood o2.
There are some dissenting views on this from medical specialists but they seem to be based around specific medical conditions which can change the way an individual responds.
Most healthy non-smokers are around 97-99% at sea level.
Airline cabins tend to be around 8000ft and most people are just a bit below 90% up there, but they don’t have to think 
(the pilots, one assumes, are used to it)
Regards the 18k+ requirement for a mask, this is the wording used in the AFMS/POH for most installed O2 systems such as commonly found in turbocharged planes. I have a reference for the FAR reg here Anything installed needs an AFMS or a POH procedure. Portable systems have no such requirements. My guess is that it was a certification requirement. BUT with constant flow systems you do need a mask at 18k, IME. It is the pulsed flow which you get from the MH O2D2 which delivers O2 more effectively which enables flight above 18k with a cannula. I have been to 21k and blood O2 was about 95% – however the O2D2 setting was not the cannula setting; it was the higher-flow mask setting 
I would not fly at 13k without O2. No way. I would expect to be very tired.
AnthonyQ wrote:
Presumably using a finger pulse-ox meter and ensuring a reading in excess of 90% would qualify as determining that a given altitude is not harmfully impairing faculties…,
That’s pretty much the way I sold it, yes. When I first bought a pulse oximeter it was about £400. The last one was $11.
Well done, bookworm
I like such “soft” regulations for private GA.
Still, I would have preferrerd the numbers under 1) to be different, i.e. “above 11000…” instead of “at 10000…”
But you can choose your own numbers, can’t you? That’s the point of paragraph (a). The ones in paragraph (b) come from the guidelines in ICAO Annex 6 Part II.
I wrote (b) as AMC, because it’s a prime example of how to comply with a rule, but it got promoted to IR.
Yes, but according to the regulation as it is now, one is not be able to fly say a one-hour flight at FL100 without at least having O2 on board. This I don’t like.
