What radio navigation equipment is required for an air carrier operating a flight in VFR over-the-top conditions where pilotage is not used?

In VFR (Visual Flight Rules) over-the-top conditions, aircraft are flying in controlled airspace where visibility can be poor or where pilots do not have visual references to navigate by, necessitating reliable navigation systems. For air carriers operating under such conditions, the requirement for dual approved independent navigation systems ensures that there is redundancy built into the navigation equipment. This means that if one system fails, the other system can still function, providing a reliable means of navigation.

The emphasis on 'dual' indicates that the systems are independent, reducing the risk of a single point of failure impacting flight safety. This setup is crucial for maintaining navigation accuracy and ensuring compliance with regulations that govern safe flight operations when visual navigation is not an option. The use of independent systems also aligns with safety practices, as it allows for cross-referencing of data, which is especially important in environments where visibility is limited.

Other options do not provide the same level of redundancy and reliability that dual independent navigation systems do, making them less suitable for VFR over-the-top conditions.