Mode S - Future ATC Systems
To all you luddites... Despite all the fears about clutter on ATC screens and controllers turning off Mode S, it is being considered as a standalone future ATC system... and I believe is either in use (or on trial) in Austria and Australia.... where the mountains in the case of the former and vast outback in the case of the latter makes normal radar systems difficult if not impossible. The idea of Primary Radar may(?) one day seem as obsolete as using morse code to transmit radio messages.