Abstract: To provide an operational collision risk calculation method to be used in the process of airspace planning, the collision risk per flight hour on flight segment was researched. The existed models were improved based on airspace planning parameters. Firstly, collision risk was analyzed when the angle between two flight segments changes from zero degree to 180 degrees in terminal area airspace and on the air-ways. Secondly, the collision risk on flight segment was expressed by the sum of the collision risk stemming from this flight segment, the other risk stemming from other flight segments,and a collision risk model was built. Finally, when the values of the parameters related to terminal area airspace planning were input into the model, collision risks of two situations were calculated, and changing trends of collision risk with parameters were analyzed. The results show that when other parameter values are given, the collision risk will increase with the increasing Required Navigation Performance value, altitude (decreasing nominal vertical distance) at different initial points of flight segment and nominal longitudinal distance (decreasing nominal vertical distance) at initial points respectively, and the collision risk will decrease with increasing angle between tracks and flight gradient respectively. In conclusion, by using the model the collision risks between aircraft for different airspace planning programs can be calculated and analyzed.

Key words: air traffic transportation, collision risk model, airspace planning, airspace safety, planning parameters