Definition
A high-pressure storage container holding aviation breathing oxygen as a compressed gas, typically charged to 1,800 or 2,400 psi, fitted with a shutoff valve, pressure gauge, and regulator that steps the high pressure down to a level safe for delivery to crew and passenger oxygen masks.
Plain English
A strong metal bottle that holds breathing oxygen under high pressure for use in flight when the air outside the aircraft is too thin to breathe normally.
Context Anchor
Seen in oxygen system discussions, preflight checks, aircraft equipment lists, and high-altitude flight planning.
Derivation
‘Cylinder’ comes from the Greek ‘kylindros,’ meaning ‘a roller’ or ‘tube-shaped object.’ The shape matters here: a cylinder is the strongest practical form for holding gas at very high pressure, which is why oxygen is stored this way rather than in a square or irregular tank.
Why Pilots Care
Provides the oxygen supply needed to avoid hypoxia during flights above 10,000 feet in unpressurized aircraft.
Grounding Statement
Think of the oxygen cylinder as the aircraft’s stored breathing-air supply for times when outside air does not provide enough oxygen for safe flight.
Intuition Check
An oxygen cylinder is not just any bottle of air. It is a specially approved high-pressure container for breathing oxygen used by people in the aircraft.
Example Sentence 1
During preflight, the pilot checked the oxygen cylinder pressure gauge and confirmed it read 1,800 psi before departing on the high-altitude leg.
Example Sentence 2
After the emergency descent, the crew replaced the depleted oxygen cylinder in the aircraft.