Throughout aviation history, a condition known as hypoxia has posed a risk to aircraft pilots, crew members, and passengers flying at high altitudes. Hypoxia occurs when the human body is exposed to high altitudes without protection. Defined as an insufficient supply of oxygen to the body’s tissues, hypoxia affects the central nervous system and organs. Brain cells, which are extremely sensitive to oxygen deprivation, can begin to die within 5 minutes after the oxygen supply has been cut off. When hypoxia lasts for longer periods of time, it can cause coma, seizures, and even brain death. Aircraft passengers exposed to either a slow, progressive increase in cabin altitude, or a sudden exposure to high cabin altitude, may show symptoms of inattentiveness, poor judgment, memory loss, and a decrease in motor coordination. Pilots afflicted with hypoxia may not be able to acknowledge the situation or take corrective action, leading to aircraft accidents or crashes.