What does a red CKPT PX warning message on the EICAS display indicate?

The red CKPT PX warning message on the EICAS display is triggered to notify the pilot when there is a critical issue with cockpit differential pressure. Specifically, it indicates that the cockpit differential pressure exceeds the normal limit of 3.9 to 4.0 psi. Maintaining appropriate cockpit pressure is vital for ensuring the safety and comfort of the crew, as excessive pressure can lead to potential risks such as structural damage or loss of pressurization.

The significance of this warning lies in its critical nature, which is reinforced by the use of a red alert, indicating an immediate concern that requires prompt attention. When the differential pressure crosses this threshold, it is essential for the crew to take appropriate corrective actions to prevent possible adverse effects on the aircraft's operation.

Understanding this warning is crucial for pilots, as it directly informs them of the aircraft's pressurization status, helping them make informed decisions about their flying environment.