What indicates a failure in an aircraft equipped with an Electronic Flight Display (EFD)?

A failure in an aircraft equipped with an Electronic Flight Display (EFD) is indicated by a bold RED X over the display. This visual cue is an industry-standard indication that alerts pilots to an instrument or system failure that requires immediate attention. The bold red color signifies a serious situation, and the cross overlay clearly communicates that the information provided by that specific instrument or system is no longer valid. Pilots are trained to recognize this indication and take appropriate action, such as verifying critical flight parameters through backup instruments or systems.

In contrast, a flashing green light typically indicates that a system is operational or in a normal state, while a steady blue light often designates that a system is in an active mode without indicating a failure. A yellow caution symbol serves as a warning that something requires attention but does not suggest an immediate or critical failure like the bold RED X does. Therefore, recognizing the bold RED X is crucial for maintaining situational awareness and ensuring safety during flight operations.