Plain English Meaning
A mask that fits over your face so you can breathe extra oxygen from the aircraft's oxygen system when there isn't enough oxygen in the cabin air.
Full Definition
A device worn over the nose and mouth (or the entire face) that delivers supplemental oxygen from an aircraft oxygen system to the user. Oxygen masks come in several types matched to the system supplying them, including continuous-flow masks for low- to medium-altitude use, diluter-demand and pressure-demand masks for higher altitudes, and quick-donning masks designed to be put on with one hand in five seconds or less.
Context Anchor
Seen in high-altitude flight planning, aircraft oxygen equipment checks, and for using oxygen in .