1. A method comprising: receiving flight parameter data relating to a plurality of flights, the flight parameter data including indications of aircraft performance based navigation (PBN) capabilities, a cleared or best available flight plan information, an aircraft configuration, and an airport configuration for the plurality of flights; assigning probabilistic properties to the flight parameter data; receiving accurate and current position and flight plan information for a plurality of aircraft corresponding to the flight parameter data; determining a probabilistic trajectory for two of the plurality of aircraft based on a combination of the probabilistic properties of the flight parameter data and the position and predicted flight plan information, the probabilistic trajectory being specific to the two aircraft and including a target spacing specification to maintain a predetermined spacing between the two aircraft at a target location with a specified probability; and generating a record of the probabilistic trajectory for the two aircraft.