And Mode S is mandatory equipment at least on the airborne side of things for the last few years already. Don't you guys on the ground use it? It did cost a lot of money to retrofit to the required enhanced surveillance level (Mode S was mandatory before, but with less transmitted data, TCAS requires Mode S). Same actually for CPDLC, datalink is required equipment for any new delivered plane since 01.01.2011 in europe, however i do know ATC has still until 2013 for full operational use.