Definition
The sudden loss of cabin pressure in a pressurized aircraft, occurring fast enough that cabin pressure equalizes with the lower outside pressure within seconds. It exposes occupants to high-altitude conditions — low oxygen, low temperature, and possible physical effects from the pressure change — and requires immediate use of supplemental oxygen and a descent to a safe altitude.
Plain English
The cabin suddenly loses its pressurized air, and within seconds the inside of the aircraft matches the thin, cold air outside. The crew must put on oxygen masks right away and descend to a lower altitude where breathing is normal again.
Context Anchor
Encountered in high-altitude and pressurized-aircraft training, especially when discussing emergency oxygen use and emergency descent procedures.
Derivation
‘Decompression’ comes from Latin de- (‘removal of’) and compressio (‘pressing together’) — literally the removal of pressure. ‘Rapid’ distinguishes it from a slow leak: it happens in seconds, not minutes.
Why Pilots Care
It can cause immediate hypoxia, physical discomfort, and requires prompt use of oxygen plus rapid descent to a safe altitude.
Grounding Statement
Picture a sealed cabin at altitude suddenly losing its pressure: the air inside rushes out, breathing becomes harder, and immediate oxygen becomes the priority.
Intuition Check
Rapid decompression is not just a draft or a loud cabin leak. It means the cabin pressure drops fast enough to create an immediate breathing and emergency-control problem.
Example Sentence 1
After the rapid decompression at FL350, the crew donned oxygen masks and began an emergency descent.
Example Sentence 2
Training emphasizes recognizing the loud noise and rushing air that signal rapid decompression.