At approximately what altitude does mild hypoxia begin to occur?

Mild hypoxia begins to become a concern at around 10,000 feet. At this altitude, the partial pressure of oxygen decreases, making it more difficult for the body to adequately supply oxygen to its tissues. While individuals may not feel immediate effects at this altitude, physiological responses start to indicate that the body is struggling with oxygen saturation. Symptoms can include reduced cognitive function, impaired coordination, and minor increases in heart rate.

At altitudes significantly above 10,000 feet, such as 14,000 feet and 20,000 feet, the risk of hypoxia increases further, leading to more pronounced effects and necessitating supplemental oxygen for many individuals, especially if exposed for prolonged periods. Understanding this threshold is crucial for crew members in ensuring safety and making informed decisions during flight operations.