This disclosure is directed to systems and methods for smart transitioning between aircraft trajectory management modes. In one example, a system is configured to track a speed of a target aircraft in flight ahead of an own aircraft on which the system is positioned. The system is further configured to determine whether the target aircraft has maintained a rate of change in speed within a selected range of variation in change of speed, for a selected period of time. The system is further configured to enable an activation of a merging trajectory management mode of the own aircraft in response to determining that the own aircraft is in a trajectory management mode transition airspace and that the target aircraft has maintained the rate of change in speed within the selected range of variation in change of speed, for the selected period of time.