Which EICAS messages cannot be removed?

The correct answer indicates that both advisories and warnings on the Engine Indication and Crew Alerting System (EICAS) cannot be removed. Warnings in particular represent critical issues that require immediate attention from the flight crew, ensuring that the necessary corrective action is taken. As such, these messages are designed to persist until the underlying problem is resolved or mitigated, emphasizing safety.

Advisories, while generally less critical than warnings, provide important information regarding aircraft systems or performance and cannot simply be dismissed. The persistence of both types of messages ensures that the crew remains aware of critical and important system statuses during flight.

The concept that all messages can be removed is not accurate because doing so would potentially allow significant issues to be overlooked, compromising the safety and integrity of the flight. Therefore, the focus on maintaining visibility of advisories and warnings is a core aspect of crew resource management and safety protocols in aviation.