Air traffic increase causes congestion at hub airports and in their terminal airspaces. Currently, air traffic is controlled per air sector/airspace. In order to assure that controllers can safely handle the air traffic in their sector, the number of aircraft in each sector is limited. One way to reduce congestion in a specific airspace is to assign the time at which an aircraft should fly over the assigned entry waypoint (fix). This control method is referred to as “time-managed flow.” In this study, we investigate the effect of time-managed flow on arrival traffic into Tokyo International Airport (Haneda Airport). The analysis uses past radar data (CARATS Open Data), provided by the Japan Civil Aviation Bureau. First, we set the congestion area as the target airspace and adjust the entry time assuming enroute time flow management. For each flight, a new trajectory is modeled based on its shortened flight time, which results from time-managed inflow. The new trajectory is selected by substituting the original trajectory with one from the dataset that matches the required flight time. The results show that time-managed traffic flow can lead to reductions in flight distance and number of heading changes in congested airspace.