Definition
Pure oxygen stored in its gas form under high pressure in steel or composite cylinders, used to supply aircraft oxygen systems for high-altitude flight. It is specially processed to remove moisture so it will not freeze in regulators or lines at altitude, and it meets a specific aviation purity standard distinct from medical or industrial oxygen.
Plain English
Oxygen kept as a gas in a pressurized bottle, dried so it won't freeze in the lines, and clean enough to be safe to breathe in flight.
Context Anchor
Seen in aircraft oxygen system descriptions, servicing instructions, high-altitude operations, and preflight checks of oxygen quantity and pressure.
Derivation
Gaseous' comes from Latin 'gas,' meaning a substance in its airy, expanded state. The label distinguishes this form from liquid oxygen (LOX), which is stored cold and as a fluid. Knowing the form matters because gaseous and liquid oxygen require completely different storage and handling.
Why Pilots Care
Provides the oxygen needed to stay conscious and alert when atmospheric pressure drops too low for normal breathing.
Grounding Statement
Picture an oxygen bottle in the aircraft: the oxygen inside is gas squeezed under pressure, ready to flow to a mask or cannula when needed.
Intuition Check
Do not assume any oxygen bottle is acceptable for aircraft breathing use. In this term, breathing oxygen means oxygen suitable for people to breathe in flight, and gaseous means it is stored as a gas under pressure.
Example Sentence 1
Before the high-altitude flight, the technician serviced the cylinder with gaseous breathing oxygen to the placarded pressure.
Example Sentence 2
During the preflight inspection the crew confirmed the pressure gauge on the gaseous breathing oxygen cylinder read in the green arc.