For what purpose do oxygen systems become critical during flight?

Oxygen systems are critical during flight primarily for the purpose of supplementing oxygen during depressurization. At high altitudes, the atmospheric pressure decreases, which leads to a reduction in the amount of oxygen available in the air. If there is a rapid decompression in the aircraft cabin—due to a structural failure or other issues—passengers and crew may experience a lack of sufficient oxygen, resulting in hypoxia, a condition that can impair cognitive and physical abilities.

The oxygen systems are designed to quickly deliver supplemental oxygen to ensure that all onboard can maintain safe and effective levels of oxygen intake until the aircraft can safely descend to a lower altitude where the oxygen levels are adequate. This function is crucial not only for safety but also for the well-being of everyone in the aircraft.

In contrast, the other choices focus either on non-essential services like enhancing the flight experience or providing entertainment, which do not directly address the physiological necessity for oxygen during emergencies. Improving engine performance, while important, does not relate to the critical need for oxygen systems in emergency scenarios related to cabin pressure loss.