Commercial Pilot License (CPL) 2025 – 400 Free Practice Questions to Pass the Exam

Hypoxia, which refers to a deficiency in the amount of oxygen reaching the tissues, can begin to become a concern at higher altitudes where the atmospheric pressure decreases and affects the availability of oxygen. Specifically, at altitudes from 12,000 feet to 15,000 feet, pilots and passengers may start to experience the onset of hypoxia due to reduced barometric pressure, which lowers the partial pressure of oxygen in the air.

At these altitudes, some individuals may begin to notice symptoms such as fatigue, decreased cognitive function, impaired motor coordination, and an overall sense of euphoria or lack of inhibition. These effects can vary among individuals, as factors such as physical fitness, acclimatization, and personal susceptibility to hypoxia play a significant role in one's body's response to altitude changes.

While hypoxia can technically begin at lower altitudes—for instance, it can occur at or above 5,000 feet in sensitive individuals—the most pronounced symptoms and risks are commonly associated with altitudes above 12,000 feet. Therefore, recognizing the range of 12,000 feet to 15,000 feet as a critical zone for the risk of hypoxia is essential for safety in aviation.