At 09:06 03 October 2019, Bruce Hoult wrote:
On Thursday, October 3, 2019 at 9:45:05 PM UTC+13, John
McLaughlin wrote:
I've searched this forum and google, but can't find the
information - can

anyone tell me what readings I should expect to see at altitude?
Presumably, a steady decrease from the ground level reading,
despite
using

supplemental oxygen? But without a table of what's normal for
each
altitude, how can you know when you need to be descending?

I believe the idea of supplemental oxygen is to keep within five
points of
your normal reading at sea level, and certainly no lower than 90.

I bought a unit a couple of weeks ago. I haven't used it in a glider
yet,
but today I spent 12 hours at 8000 ft pressure (presumably) in a
B777. I
dropped to 92-93 instead of my normal 96-97.

Supplementary oxygen should maintain your normal reading of
around 96-97 up to the altitude where your oxygen system starts to
be unable to keep up. That altitude will depend on a number of
factors.

For anyone with a personal interest in survival while flying gliders at
altitude, I cannot recommend too highly the book by Jean-Marie
Clement "Dancing with the wind" which has 40 pages on "Oxygen:
basic physiological aspects, applied research, and management of
EDS". This chapter was written in collaboration with a qualified
medical expert and glider pilot, who in turn had carried out practical
research with the founder of Mountain High. This chapter alone is
worth the price of the book for serious high-altitude glider pilots.

It has interesting things to say about the FAA regulations:

"When the reader has finished this chapter, it will be tempting to
conclude that these aviation regulations are most generous, but the
most likely to result in accidents".

The chapter on "Health, altitude and long flights" is also very
informative. And the pictures throughout are amazing.

Mike