Adhering to the US mandate would've been better for everyone. It would've given Defence plenty of time to upgrade their aircraft, it would have ensured that the avionics industry was ready to supply slightly less ridiculously priced equipment for the small end of the GA market (I'm not looking forward to paying $10,000 to put a 1090ES transponder and TSO'd GPS into my $30,000 day VFR C152 so I can fly it to Canberra occasionally), and would have ensured that manufacturers of airframes with very tightly integrated avionics (such as Dick's CJ3) would have had upgrades available.
Originally Posted by Check_Thrust
Yes, Australia is one of the first, but others are joining us on the exact same date.
Australia decided to go it alone before the rest of the world for little apparent reason other than to give CASA staff something to brag about to their mates in Montreal. A small handful of relatively minor regional players, such as Indonesia, Singapore and Vietnam just happened to follow.
Europe and the USA are the two largest markets for aircraft, and in particular GA aircraft. Europe's mandate is 1 August 2013 for new aircraft, and and 12 July 2017 for retrofits, and only applies to aircraft >5700kg or max cruise >250kts TAS (aircraft not meeting those criteria only need basic Mode S capability.) The USA's mandate is of course 2020.
Given that the vast majority of bizjets would be flying in either of those two jurisdictions or other jurisdictions with no ADS-B mandate at all, most of Cessna's customers would undoubtedly be happy enough with Cessna's current upgrade availability for next year.