What are the indications of cockpit under pressurization?

The indication of cockpit under pressurization, specifically the amber cockpit altitude annunciator that activates when the pressure altitude exceeds 18,000 feet, signifies that the pressurization system is not maintaining the desired cabin altitude. This warning alerts the crew to the potential for hypoxia or discomfort due to insufficient cabin pressure, prompting immediate action to assess and address the pressurization status.

The amber color indicates a caution or warning, distinguishing it from more severe alerts. This mechanism is vital for maintaining safety in high-altitude flight operations, where managing cabin pressure is essential for passenger and crew health.

Options that mention red lights or alarms may suggest different conditions or alerts unrelated to the specific situation of under pressurization. Visual and sound alarms on their own without specific context about cockpit altitude are less reliable as indicators of the specific pressure-related issue that the amber annunciator addresses.