On Oct 30, 2:06 pm, Ron Natalie wrote:
Stefan wrote:
I've heard that above some altitude, the FARs require the use of an
oxygen mask rather than a cannula in US registered aircraft. Where do I
find this requirement? (FAR 91.211 doesn't mention it.)

Thanks
Stefan

The FARs don't care if you suck off the regulator directly.
What's effective is another story.

Is the pilot obligated to follow the certification of the O2 system?

-Robert