Definition
A rapid loss of cabin pressure in a pressurized aircraft, occurring fast enough to produce noticeable physical effects on occupants and the aircraft structure, but slower than an explosive decompression. It typically results from a failure of the pressurization system or a small breach in the pressure vessel.
Plain English
The air inside the cabin escapes quickly, dropping the cabin to the outside air pressure in a matter of seconds. It happens fast enough to be alarming and dangerous, but not instantaneous like a blown-out window or door.
Context Anchor
Encountered in high-altitude flying, pressurization-system discussions, emergency procedures, and oxygen-mask training.
Derivation
Decompression comes from Latin de- (reversal, removal) and comprimere (to press together). So decompression literally means the undoing of pressure. Sudden distinguishes it from a slow leak and from an explosive (near-instantaneous) decompression.
Why Pilots Care
It causes immediate hypoxia risk, physical pain, and forces rapid emergency descent while using oxygen masks.
Grounding Statement
At altitude, a failed seal or opening in the aircraft can let cabin pressure drop in moments, making oxygen and descent time-critical.
Intuition Check
Sudden decompression does not always mean an explosion or the airplane breaking apart. It means the cabin pressure drops quickly enough to create an immediate breathing and safety problem.
Example Sentence 1
After the outflow valve failed at FL350, the crew experienced a sudden decompression and immediately donned oxygen masks before initiating an emergency descent.
Example Sentence 2
The pilot initiated an emergency descent to reach breathable air following the sudden decompression.