Free Flight vs. Centralized Air Traffic Management

The current Air Traffic Management system is subject to structural changes, which are expected over the next 20 years.These changes are required for a number of reasons:  The current system inflicts delays and fuel inefficiencies to flights (as demonstrated by the historic Paris-Miami Air France flight in April 2010)  The current system has structural and operational capacity limitations  Under current system, the complexity of the Air Traffic Controller's work increases steeply with traffic  Voice communication on a single radio frequency in ATC is limitative and subject to errors  Safety is sometimes jeopardized and separation relies on a safety net (ACAS)  The introduction of the ACAS systems as a separation safety net presents a structural risk in the classic ATC philosophy (as demonstrated by the Überlingen 2002 mid-air collision)  ATM is the only system left in Civil Aviation, with virtually no automated core processThere is a major choice to make for the future Air Traffic Management automation in both NextGen and SESAR programs: the free flight concept, and the opposite, the centralized management.This paper is an assessment of both scenarios, and their implications for traffic capacity, air traffic control complexity, safety and efficiency.