Passing FL190, I heard an aural warning from the EDS
02D2 controller and quickly realized oxygen had stopped flowing (it's a
new, freshly filled tank). I quickly turned the controller to R/M
(manual) expecting to get a positive flow but nothing was
happening. I had a fresh set of batteries installed and there were no
red failure lights showing. Needless to say, the effects of hypoxia come
on quickly and I immediately initiated a descent.
Back on the ground I found that if I turned the unit off
then back on, it would work again.
I plan on calling MH on Monday and asking them about it,
but wanted to see if anyone in the group knows if this problem was related to
not using the face mask at the prescribed altitude.