They do not incorporate ADSB-IN because currently, it is not secure. No one wants a way in that is not encrypted.
Note that while ASA states they 'accept' ADSB-2, they also instruct foreign operators using ADSB-2, that they must set the NIC to '0'. This indicates no integrity of the signal and the corresponding location. So, in effect, what is shown on the ATC screen?
Bottom line, the US has mandated ADSB-2, so will ICAO, even for GA. ATC systems and aircraft systems will be built around ADSB-2. The graph above shows Boeing providing that with all new ac, and retro fitting existing ac. Mandating ADSB V0 will just create additional costs to upgrade to v2 in the very near future.
As noted above by ASA, TCAS will be affected, mostly because of the integration of ADSB and TCAS. Jeppeson, Garmin, and ASA all state the ADSB, ADSB V2 systems are not compatible.
Last edited by underfire; 17th Dec 2016 at 04:47.