What are the effects of hypercapnia on flight performance?

• A. Headache, dizziness, impaired judgment, reduced reaction time, and possible altered consciousness
• B. Improved cognitive function
• C. Decreased heart rate without symptoms
• D. No effect on performance

Answer: (A)

Elevated CO2 levels disrupt brain function and how the body regulates respiration, which directly harms flight performance. When CO2 rises, cerebral blood flow increases (cerebral vasodilation) and the blood becomes more acidic, affecting neurons. This leads to symptoms like headache and dizziness and slows processing and decision making. As a result, judgment becomes impaired, reaction times are longer, and there is a real risk of progressing to altered consciousness with higher CO2 levels. In flight, even mild hypercapnia can degrade situational awareness and control accuracy, increasing the chance of error.

The other options don’t fit because hypercapnia does not improve cognitive function, and it often causes sympathetic responses like increased heart rate rather than a decrease. It also does have measurable effects on performance, so saying there is no effect isn’t accurate.