Originally Posted by
Lead Balloon
But the ‘blindspot’ is that it requires ‘something’ to be interrogating the other aircraft’s transponder….
Are you certain about that for ADSB units? I’ve been reading a lot about ADSB since fitting a new transponder last week and I hadn’t thought about that. I know that’s how Mode C works and the issues with TCAS versus PCAS but experience tells me that even a skyecho can be detected by another skyecho when not in range of a ground ADSB station and they don’t have a mode Charlie to be interrogated by radar, unless somehow it’s being interrogated by something that I’m not aware of.
I’m finding ADSB is generally not well understood by pilots. For example I keep hearing statements like “I know my ADSB is working because ATC knew my callsign” from pilots not realising that they are equipped with Mode-S transponders. I also understand that close to Melbourne and Sydney for example, that ATC see only Mode C/S and that ADSB is only visible to them outside of primary radar coverage. Moorabbin for example told me that they don’t have ADSB at all.
If anyone knows more specifics about what the controller sees, I would love to hear more. I also understand that some gps inputs are approved and some are certified and the ATC can see both, however they appear as grey for ADSB 2020 approved and green for certified, and of course only outside of traditional mode C/S radar coverage.