Definition
A self-contained, transportable oxygen supply system consisting of a small high-pressure cylinder, a regulator, and a mask or cannula, used to provide supplemental oxygen to pilots and passengers in aircraft not equipped with a built-in oxygen system or as a backup to such a system.
Plain English
A small, carry-on oxygen kit you bring into the aircraft. It includes a bottle of oxygen, a knob or valve to control the flow, and a mask or nose tube to breathe through.
Context Anchor
Seen in high-altitude flight planning, aircraft equipment checks, and discussions of oxygen use in the Pilot’s Handbook of Aeronautical Knowledge.
Derivation
Portable comes from the Latin word meaning “to carry.” Equipment means the things needed for a job. Together, the phrase points to oxygen gear that can be carried aboard and used without being permanently built into the aircraft.
Why Pilots Care
Allows pilots to meet FAA oxygen requirements and avoid hypoxia on flights where cabin pressure altitude would otherwise become unsafe.
Intuition Check
Do not read “portable” as “any oxygen bottle you can bring along.” In aviation, portable oxygen equipment means a proper oxygen setup for flight, with the cylinder and breathing parts arranged so occupants can use it safely in the aircraft.
Example Sentence 1
Before the cross-country flight at 12,500 feet, the pilot loaded a portable oxygen unit into the cabin and briefed her passenger on how to use the mask.
Example Sentence 2
During the preflight inspection the student confirmed the portable oxygen equipment was secured and had adequate supply remaining.