The strategic vision of the civil aviation community is to achieve integrated global air traffic management through the worldwide implementation of Communications, Navigation, Surveillance and Air Traffic management (CNS/ATM) systems in a progressive, cost-effective and co-operative manner. Existing books cover only general aspects, while details are scattered across professional magazines and ICAO publications. As the states (providers of service) and users (airlines) collectively address the next steps to achieve an integrated, global air traffic management system using a single sky approach which is safe, seamless and smart, "Seamless Sky" provides a means to achieve it. Apart from providing a background to the development of the CNS/ATM systems concept, it covers ATM aspects, technical features of CNS, the planning mechanism, operational scenarios and harmonization issues with details in step-by-step approach for its implementation eventually giving rise to a seamless sky. The book mainly focuses on operational and technical aspects of CNS/ATM systems and should serve the basic needs of state planners, civil aviation professionals and pilots. It is designed to be user friendly with numerous decision trees, practical tips and flow charts. It incorporates current practices in the states/industry and at the same elaborates future trends through the ongoing work programme of ICAO. It also discusses the institutional aspects, interoperability and harmonization of systems and procedures. It shows the reader how to establish the CNS/ATM infrastructure using a co-operative and cost effective approach and provides the means to harmonize the implementation between states and users using appropriate tools and mechanisms.