What is the typical cabin altitude maintained by the CACS during flight?

The typical cabin altitude maintained by the Cabin Atmosphere Control System (CACS) during flight is generally between 6,000 to 8,000 feet. This range is vital for maximizing passenger comfort while balancing the need to maintain a pressurized environment.

At altitudes above 8,000 feet, the partial pressure of oxygen begins to decrease, which can lead to discomfort or even hypoxia in unacclimatized individuals. By keeping the cabin altitude in the range of 6,000 to 8,000 feet, the CACS helps ensure that the oxygen levels remain sufficient for passenger comfort and safety. This altitude is also a compromise that allows for efficient aircraft performance and structural integrity while providing an acceptable environment for those onboard during a flight at higher altitudes.

Other options suggest cabin altitudes either too low or too high, which would not provide the necessary balance between passenger comfort and operational efficiency. Maintaining cabin altitude at sea level is impractical at cruising altitudes due to the structural and engineering limits of aircraft and would require an excessive amount of energy and resources to achieve.