Where does hypoxia typically affect cognitive functions best?

Hypoxia, which is a deficiency in oxygen reaching the tissues, starts to affect cognitive functions as altitude increases due to the reduced partial pressure of oxygen in the atmosphere. The impact on cognitive function becomes more pronounced particularly in the range of 12,000 to 15,000 feet.

At this altitude, the body can still compensate to some extent, but the lack of sufficient oxygen can lead to impaired judgment, decreased cognitive abilities, and slower reaction times. This range is critical because it is where the majority of unacclimatized individuals begin to experience significant physiological effects.

Above 15,000 feet, while hypoxia continues to worsen, many pilots, including those who are inexperienced, may already be experiencing severe cognitive decline. Therefore, the 12,000 to 15,000-foot range is where initial and noticeable cognitive impairments typically manifest, which is why this option is the most accurate in relation to when hypoxia affects cognitive functions.