and if only the ground-based bits of that system could overcome the laws of physics and see all transponding a/c regardless of height/land screening etc AND if only the airborne users of such a system could guarantee the 'tickling stick' of the other a/c's IFF gave your kit an idea of where it is going despite all their mnvring etc....hmm, perhaps the good old "tell people what you are doing" still has some merit? Also, as recent reports have highlighted, relying on such technology gives an often false sense of security, especially given the number of sorties flown with u/s transponders.....