What occurs if the red Cabin Alt High CAS message is illuminated?

When the red Cabin Alt High CAS message is illuminated, it indicates that the cabin altitude has exceeded a predefined threshold, signaling that the aircraft’s cabin is pressurized at a level that is higher than what is deemed safe for crew and passengers. This situation usually arises due to a failure in the cabin pressurization system, resulting in a significant drop in cabin pressure, which can lead to hypoxia—a condition where the body is deprived of adequate oxygen.

In aviation, maintaining proper cabin pressure is crucial for ensuring the safety and comfort of everyone onboard, especially at higher altitudes where the outside air pressure is significantly lower. The warning allows the flight crew to take necessary actions to either descend to a lower altitude where the external air pressure is sufficient, or correct the issue with the pressurization system if possible.

Thus, the illumination of the red Cabin Alt High warning serves as a critical alert to address potentially dangerous altitude conditions proactively.