What is the key characteristic of RNAV alternate means of navigation?

The key characteristic of RNAV alternate means of navigation is that it involves using a suitable RNAV (Area Navigation) system without the necessity for additional monitoring. This means that the RNAV system is capable of navigating reliably to an alternate airport based solely on the data it receives and processes, ensuring that a pilot can navigate effectively even in conditions where traditional navigation aids may not be available or practical.

This capability underlines the flexibility and efficiency RNAV provides in modern aviation, allowing for routes that are not strictly limited to the presence of conventional navigational aids. It supports improved flight planning and enhances safety by enabling aircraft to navigate using GPS or other advanced systems, minimizing dependence on ground-based navaids.

The other options do not accurately capture the essence of what RNAV alternate navigation is about, as they either limit RNAV to conventional aids, suggest a need for backup systems when RNAV fails, or imply a requirement for dual navigation systems, which is not a characteristic of using a single capable RNAV system effectively.