1. Method of predicting collisions between a mission air vehicle and an airborne object of a plurality of airborne objects present in a flight scenario of the mission air vehicle, said mission air vehicle and said airborne object moving along respective routes including fly-by or fixed radius waypoints with which corresponding turn circumferences are associated, the method comprising: acquiring data representing state of flight and flight parameters of the plurality of airborne objects; acquiring data representing state of flight and flight parameters of the mission air vehicle; assigning to each of said airborne objects a deterministic or probabilistic mode of calculating the collision prediction; determining, among said plurality of airborne objects, a subset of airborne objects to be surveilled; calculating, for the mission air vehicle and for each airborne object of said subset, equivalent routes found by replacing each of the fly-by of fixed radius waypoints with a pair of virtual waypoints which form the entry and exit points of the respective associated circumference; synchronizing the equivalent route of the mission air vehicle with the equivalent route of each airborne object of said subset, thus obtaining synchronized routes comprising an equal number of synchronized legs flown by the mission air vehicle and by the airborne object in an identical time interval, said legs linking two consecutive waypoints at which the mission air vehicle or the airborne object changes a flight parameter; and calculating, for each airborne object, a collision prediction based on said synchronized routes according to said assigned deterministic or probabilistic calculation mode.