Abstract: A method and system of maintaining continuity of computer control and information exchange between moving vehicles such as aircraft and a computer, with a different computer being operative as a given moving vehicle moves from a first defined sector to a second defined sector, the data link between each computer and the moving vehicles located in its sector being provided by radio transmission. Each sector has a different given transmission frequency. A transition area is defined at the interface between the first and second defined sectors wherein the moving vehicle is under joint control of the computers of the successive sectors.

Abstract: A method and system of preventing collisions between aircraft comprising defining an imaginary airspace around the center of each aircraft, the airspace having a given radius (R) and height (H), and moving with and at the same velocity as the aircraft. An imaginary airspace having zero velocity is defined around objects of terrain and the parameters of each defined airspace are updated as the corresponding aircraft travels. The parameters of each aircraft defined airspace is compared one at a time with the parameters of all other defined airspaces within a discrete altitute band under predetermined criteria to determine whether there is an existing or future travel course conflict, and an indication is produced in the event such a conflict is determined.