Ever wonder how the FAA came up with 91.211 requiring oxygen use above 12,500 feet MSL for more than 30 minutes and any time over 14,000 feet MSL? The answer is geography, not physiology. When these rules were written, oxygen systems were expensive and heavy. General aviation wanted to fly anywhere in the U.S. without oxygen, and you can fly any mountain pass in the 48 contiguous U.S. states in less than 30 minutes between 12,500 feet and 14,000 feet MSL.
Physiology Matters
The problem is that these rules ignore physiology and today’s availability of inexpensive, efficient oxygen devices.
