Anyone flown into Sun & Fun in the US? If so you'll know how disciplined they are there - no radio talk only listening. PFA tried a similar system at Cranfield one year but some people didn't follow the correct entry procedure and wanted to tell their life history over the radio. The basic premise at S & F is to get everyone into a line a few miles out (Lake Parker Power station) so that people were not joining the circuit from random directions and landing instructions issued when downwind and on finals. Again no air to ground - acknowledgement by rocking your wings.