Ray, just a thought, but the warmth from your hand might keep it well
above that temperature... even though your fingers sometimes feel like
they are going to break off.

Ray Lovinggood wrote:

I've not flown in wave, yet, but I would guess the
cockpit could get rather cold. The spec sheet for
this oximeter shows the operating range from 39 degrees
F to 109 degrees F.

Can cockpit temps drop lower than 39 F at oxygen altitudes?

Ray Lovinggood
Carrboro, North Carolina USA