Definition
A specific grade of oxygen produced and certified for use in aircraft breathing systems. It is held to a very low moisture content (typically no more than 0.005 mg of water vapor per liter of gas) to prevent freezing and blockage of regulators, valves, and lines at the low temperatures encountered at altitude.
Plain English
The kind of oxygen pilots and passengers breathe from an aircraft oxygen system. It is dried out far more than medical or industrial oxygen so that the moisture in it cannot freeze and clog the equipment when the air gets very cold at altitude.
Context Anchor
Seen when checking, servicing, or using an aircraft oxygen system for high-altitude flight.
Derivation
Aviator comes from the Latin word avis, meaning bird, and came to mean a person who flies an aircraft. Oxygen is the gas the body needs to keep functioning. Together, the phrase points to oxygen prepared specifically for people flying aircraft.
Why Pilots Care
Using a non-aviation grade can introduce moisture that freezes in the regulator or toxic impurities that become dangerous at altitude.
Grounding Statement
At altitude, the oxygen system must deliver clean, dry oxygen reliably every time the pilot breathes from it.
Intuition Check
Do not assume “oxygen is oxygen.” For aircraft use, the oxygen must be clean, very dry, and approved for aviation oxygen systems.
Example Sentence 1
Before the high-altitude flight, the technician confirmed the bottle had been serviced with aviator's breathing oxygen.
Example Sentence 2
Maintenance replaced the supply with fresh aviators breathing oxygen after the last flight.