On Thursday, October 1, 2015 at 4:45:30 PM UTC-7, Darryl Ramm wrote:
UAT-Out devices support optionally not broadcasting the aircraft's ICAO address. Which obviously only "works" if you are flying without a transponder or if you have a Mode-C transponder. Mode S transponders are required to transmit the ICAO address.

All that is a poor decision IMNSHO. But something AOPA and others wanted. And the FAA offered as an inducement for GA to adopt ADS-B out. That's back in the days where all the "FAA happy think" had GA on UAT and only the big boys on 1090ES. If AOPA had its head not in a dark space they would have insisted on a much simpler and much more likely to be usable single link Mode-S 1090ES based system.


Yup.

Nobody thought it all the way through and now we have an immensely complex rat's nest.