Definition
The corrective action taken to reverse hyperventilation by rebuilding the body's carbon dioxide (CO2) concentration back to normal levels. This is achieved by slowing the breathing rate, breathing into a paper bag, or talking aloud, which causes the pilot to retain and re-inhale exhaled CO2 rather than continuing to expel it through rapid or deep breathing.
Plain English
Bringing the amount of carbon dioxide in your blood back up to normal after you've breathed it out too quickly. You do this by slowing your breathing or breathing into a paper bag so you take some of the CO2 back in.
Context Anchor
Seen in aeromedical factors when learning how to recognize and recover from hyperventilation in flight.
Derivation
Carbon dioxide means a gas made of carbon and two parts oxygen; di- means two. In this context, it helps to know that carbon dioxide is not just an exhaust gas your body gets rid of—it is also part of the normal balance your body needs for you to feel and function properly.
Why Pilots Care
Failure to restore carbon dioxide levels can prolong symptoms such as dizziness and tingling that impair a pilot's ability to maintain aircraft control and make sound decisions.
Grounding Statement
If a pilot breathes too fast for the body’s needs, carbon dioxide drops too low; slowing the breathing lets that level come back toward normal.
Intuition Check
Do not assume carbon dioxide is always just something bad to get rid of. In the body, too little carbon dioxide can cause real symptoms, so restoring it means returning to a normal balance, not adding something harmful.
Example Sentence 1
Feeling lightheaded and tingling in his fingers, the pilot recognized hyperventilation and began restoring the carbon dioxide level in the body by slowing his breathing and talking aloud to ATC.
Example Sentence 2
In training, students practice restoring the carbon dioxide level in the body to quickly relieve tingling sensations and lightheadedness.