What automatically sets CRZ thrust on the EICAS?

The correct response is that CRZ thrust is automatically set on the Engine Indication and Crew Alerting System (EICAS) when the aircraft reaches its preselected altitude, provided this occurs for at least 90 seconds. During this time, the system assesses that the aircraft is stabilizing at the target flight level, enabling the engines to transition to cruise thrust settings efficiently. This transition helps optimize fuel consumption and engine performance while maintaining the intended airspeed and altitude, which is crucial during the cruise phase of flight.

The other options do not accurately reflect the conditions under which CRZ thrust is activated. For instance, CRZ thrust is not set simply at any altitude or merely based on proximity to a selected speed, as this does not ensure the aircraft has stabilized. Furthermore, CRZ thrust is not activated just because the aircraft descends to cruise; stabilization at a specific altitude for a designated time is essential for the proper deployment of cruise thrust settings.