Air traffic management (ATM) involves collaborative work from several actors: traffic flow managers, air traffic controllers (controllers) and pilots. The ever-increasing demand for commercial air travel poses great challenges to today's airspace-centered ATM system in which each controller only undertakes the responsibility to control the aircraft flying through her/his own airspace (sector). Any aircraft bunching occurring in a sector has the potential to cause the risk of instant traffic overload in another sector. It is therefore essential to further decentralize the system by redistributing the responsibility as well as workload. This paper presents our research to support this redistribution by setting up a methodological framework using multi-agent coordination techniques. A recently identified problem, i.e. real-time traffic synchronization, is chosen as the first application.