What is the purpose of the XFER button on the CNC?

The function of the XFER button on the CNC (Communication Navigation Control) is specifically designed to alternate between the active and standby frequency. When the XFER button is pressed, it facilitates a smooth transition between frequencies, allowing pilots to manage their communication channels more effectively. This is particularly important in operational environments where radio communication must be seamless and efficient, ensuring that the crew can maintain contact with air traffic control and other aircraft without interruption.

The other choices reflect different operative functions that are not associated with the XFER button. For instance, while setting frequencies and changing communication modes are critical tasks in cockpit operations, they are managed through different controls or buttons on the CNC system. This distinction clarifies the primary utility of the XFER button in managing frequency selection, highlighting its importance in effective communication during flight operations.