Oxygen range
Recently saw the phrase `oxygen range' referred to under range circles, in the context of a divert.
It's an expression I've never heard of before.
I'd assumed it means the range circle within which stored oxygen will last in the event of a pressurisation failure, allowing one to continue to fly at altitude - but that can't be right - isn't SOP to descent to a safe altitude to avoid hypoxia?
Puzzled...