posted on Sep, 6 2014 @ 09:43 AM
Many un pressurised single engine aircraft are capable of flight above 10k... It's more efficient in many cases.
Even my lowly piper Cherokee is capable of 14k. Short periods above 10k are ok without oxygen, above 14k you are supposed to have oxy on at all times.
Pressurisation is not required, just something to breathe...
To cruise at height for efficiency you just use a portable oxygen system. Cheap and effective, just a cannula under the nose or basic mask...
As for masks dropping upon loss of cabin pressure... The aircraft here is no airliner. The crew have masks available, passengers generally don't. In
the event of an issue the idea is the pilot dons their mask and descends to below 10k for the passenger comfort.
....hypoxia, low oxygen ...No, brain damage is NOT an issue at 25k... Unconsciousness, but just fine upon coming around(once the shocking headache
wears off) ANOXIA...the absence of oxygen, THAT will cause brain damage or death... Much higher altitudes for that issue.
Outflow valve... Yes possible, but also possible is a pressurisation pack failure... If pressure is not coming in a working valve on the way out
won't help... That said, valve more likely as pack failure would be less subtle.