The Collaborative Tactical Flow Management System (CTFMS) is being developed to proactively manage air traffic and prevent congestion in air routes. Effective flow management requires the accurate forecasting of traffic demand in key airspace sectors and major airports, which necessitates the prediction of precise, time-based aircraft trajectories (4D trajectories: three-dimensional position plus time) using flight plans, radar tracking data and meteorological information. When predicted traffic demand exceeds the operational capacity of an airspace sector or airport, the system must be able to adjust scheduled ground departure times or recommend alternative flight routes. Key flow management functions of CTFMS include the Ground Delay Program (GDP), Airspace Flow Program (AFP), re-routing operations, and coordination of flow management efforts within the Asia-Pacific region. Trial operations of the initial prototype are scheduled to be conducted at the Air Traffic Control Center of the Ministry of Land, Infrastructure and Transport (MOLIT).