Plain English Meaning

The pressure inside the cabin drops, either slowly or suddenly, until it matches the thinner air outside the aircraft.

Full Definition

The reduction of pressure inside a sealed volume, most commonly the loss of cabin pressure in a pressurized aircraft. Decompression can be slow (a gradual leak through a faulty seal or valve) or rapid (a sudden structural failure such as a window or door losing integrity), and it exposes occupants to the lower ambient pressure of the surrounding atmosphere.

Context Anchor

Seen in high-altitude operations, pressurization system discussions, oxygen-mask procedures, and .