What occurs when a field select key is pressed on the RMU?

When a field select key is pressed on the RMU (Radio Management Unit), a rectangular cursor appears in that field. This visual cue indicates that the selected field is now active and ready for input. It allows the pilot to make adjustments to the parameters displayed, facilitating ease of operation during flight. The appearance of the cursor signifies to the pilot that the system is acknowledging the selection and awaits further input, such as entering a frequency or modifying a setting.

In operational contexts, this feature is essential for smooth and efficient management of the aircraft's communication and navigation systems, as it enables pilots to quickly and accurately make changes without confusion. Since the other choices do not describe the action that occurs when the field select key is pressed, they serve as alternate scenarios that do not apply in this instance.