Plain English Meaning

An airplane built so that the inside of the cabin holds more air pressure than the thin air outside. This lets people on board breathe easily and stay comfortable while the plane flies very high.

Full Definition

An aircraft equipped with a sealed cabin and a system that pumps and regulates conditioned air inside the fuselage so that the cabin maintains a higher air pressure than the surrounding outside atmosphere at altitude. This allows occupants to breathe normally and remain comfortable while the aircraft flies at altitudes where the outside air is too thin to sustain unaided human function.

Context Anchor

Seen in high-altitude operations, aircraft systems discussions, oxygen requirements, and cabin checks.