Non-Pressurized Aircraft Cruise
Looking for opinions... I'm sure there are many here.
Say you are going to fly single-pilot in an unpressurized aircraft and you will spend upwards of 2 hours at cruise. Let's assume it is fully IFR capable.
You have an oxygen system, but no emergency backup oxygen.
How high are you willing to cruise for 2 hours on your O2 system with no backup?