Which component is used for back-up navigation radio tuning?

The RMP, or Radio Management Panel, is the component responsible for back-up navigation radio tuning on the A320. This panel allows pilots to manually manage and input radio frequencies necessary for navigation, particularly when reliance on automatic systems is inadequate or inoperative.

The RMP is crucial in situations where pilots need quick access to radio tuning without depending solely on the Flight Management and Guidance Computer (FMGC). The design of the RMP gives pilots the ability to directly interact with navigation radios, ensuring they can maintain situational awareness and assist in navigation under various conditions.

In contrast, the ACP (Audio Control Panel) primarily controls audio outputs and communications, the CVR (Cockpit Voice Recorder) captures cockpit conversations for safety and investigative purposes, and the FMGC is primarily responsible for managing flight management functions including navigation but does not serve as a backup radio tuning source.