What prefix should be used for air taxis and commercial operators without FAA authorized call signs?

The appropriate prefix for air taxis and commercial operators that do not have FAA authorized call signs is "Tango" followed by "November" and the registration number. This convention is specifically designed to ensure clarity and standardization in communications.

Using the prefix "Tango" identifies the operation as an air taxi, while adding "November" signifies that it is using the aircraft's registration number in a way that complies with aviation communication protocols. This format helps air traffic controllers quickly recognize and understand the nature of the flight and its operational identification, thereby ensuring safer and more efficient air traffic management.

The other prefixes listed do not conform to the standard operational codes used in the aviation industry, which seek to maintain a consistent and easy to understand system for all air traffic communications.