Pilots of modern aircraft cannot rely only on visual abilities and piloting skills to maintain acceptably safe separation from other aircraft, thus a considerable proportion of contemporary flights are performed under instrument flight rules with the responsibility for separation belonging to air traffic control (ATC). However, as the air traffic growth in the end of the 20th century and in the beginning of the 21st[4][5][6][7] is straining the ATC capacity, researchers on aviation and air transport are trying to propose operational and technological improvements in order to cope with this strain, one of which is self-separation.