Definition
The process of removing dissolved nitrogen from the body by breathing 100% oxygen for a period of time before exposure to high altitude. This reduces the risk of decompression sickness when flying at altitudes where ambient pressure is significantly lower than at the surface.
Plain English
Breathing pure oxygen for a while before a high-altitude flight to flush nitrogen out of your blood and tissues, so it doesn't form bubbles when the cabin pressure drops.
Context Anchor
Seen in high-altitude flight, pressure-suit, and sudden cabin-pressure-loss discussions, especially when pilots pre-breathe oxygen before ascent.
Derivation
Built from 'de-' (removal) and 'nitrogen' (the gas that makes up about 78% of the air we breathe). Literally, 'taking the nitrogen out.' Knowing the parts confirms what the procedure does: it strips nitrogen from the body before flight.
Why Pilots Care
It prevents decompression sickness when cabin or ambient pressure drops suddenly at altitude.
Grounding Statement
Before a very high-altitude flight, a pilot may sit breathing pure oxygen so nitrogen slowly leaves the body through normal breathing.
Intuition Check
Denitrogenation does not mean simply “getting more oxygen.” It means using pure oxygen to wash nitrogen out of the body before low-pressure exposure.
Example Sentence 1
Before climbing to extreme altitude in an unpressurized aircraft, the pilot completed a denitrogenation period by breathing 100% oxygen for an hour.
Example Sentence 2
Adequate denitrogenation before the flight reduced the risk of joint pain after an unexpected decompression.