Someone please correct me if I'm wrong but I'm fairly sure that the range of ground radar is far more than 30 miles. For example, flights departing out of JFK going to Caribbean destinations are on radar as far out as roughly 200 miles, possibly more. Of course the range of a radar site will depend on the altitude of the aircraft.
And as far as the available technology, there would be ways to track in-flight aircraft anywhere in the world through a GPS-based type of system. In fact, many aircraft already transmit their lat/long position on 1090 MHz (ADS-B) which can be received on the ground. I don't see why a system based on this could be developed using satellites. It would mean that every aircraft would need to transmit their lat/long coordinates.