Backup radio site identification in air traffic control systems

The identification of backup radio sites, to increase the availability of the future air/ground (A/G) air traffic control (ATC) systems, is investigated, When there is an A/G communications failure, due to a radio site or an ATC controller access failure, another site (or sites) provides the service. The backup site should be capable of providing full coverage of the desired airspace known as the service volume. Meeting the full coverage conditions by one site or a group of sites is analyzed. It is concluded that identification of one site providing full coverage can be determined easily. The identification of a group of sites, each with partial coverage and providing full coverage is analyzed in detail. An algorithm involving both analytical and numerical approaches is described. It determines if two radio sites with given geographical coordinates, and each with partial coverage of a given cylindrical service volume, can provide full coverage. This algorithm can be implemented as a computer program to process a database of radio sites.