In article ,
says...

Hey, here in Switzerland I'm only at 1300 feet above sea level. When in the
Alps I use the D10 setting just to make sure that I my concentration and
reaction times are 100%. Al's right, though. Most people should be able to
do just fine with a hit on the bottle at 12,000.

Maybe not, since people flying gliders at Minden are not "most
people", but tend to be older than "most people". On a hot soaring day
at Minden, or elsewhere in the high desert ares, density altitudes can
easily be 8000' or higher. Nasal cannulas are comfortable enough, and
the newer oxygen systems economical enough (especially the EDS
system), that I'd say there is little reason for "most people" to
wait until 12,000' shows on their altimeter, which could easily be a
density altitude of 15,000' or more.

If this seems much too conservative, talk to some of the increasing
numbers of pilots using oximeters in flight. You will likely be
surprised at how many had oxygen saturations much lower than you'd
suspect from their age and fitness. Even better, try to borrow one for
a flight, or at least check your saturation while on the ground
shortly before the flight.

Personally, I turn my EDS on before 10,000' and set it for Night
(surface start). If the cost of oxygen concerns you, get a more
economical system, and/or learn how to fill your oxygen tank yourself,
as many of us do. This reduces the cost of a fill to about $5.

Guess it does not make a
lot of sense for people from the 'city' to show up in Minden for a flight
without breathing some clean air for a day or so before zooming off into the
boondocks. For some it must feel like 30,000 as they release from tow. Wow.

A good suggestion that most will ignore, but the effect can be
mitigated by starting the oxygen at launch, or soon after release.

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Eric Greenwell
Richland, WA (USA)