Wondered much the same so emailed Microair:
G’day Microair
Sounds like an affordable upgrade however do you not have to have Mode S capabilities in order to be fully ADSB compliant?
Regards
Thanks for your email.
The short answer is no.
The complicated answer is…. Mode S provides ADSB In and Out but more importantly communicates a significant amount of additional aircraft vector information. Australia is one of very few countries (I actually don’t know any others) where you can no longer buy a Mode A/C on new certified installations (you’re allowed only a Mode S). We are currently challenging CASA but it may take some time to reverse the Mode S decision for LSA operators. However, for customers with existing Mode A/C installations, then the minimum requirement set by our NAA is for an ADS-B Out device only. The government is now trying to improve the number of ADS-B Out compliant aircraft because (as you can imagine) not everyone has jumped onboard the Mode S bandwagon. It is why we are not currently selling a new T2000ADSB in Australia but only providing the upgrade should you already have an installed T2000SFL.
In most other countries the minimum requirement for operating outside of Class A airspace is only for an ADS-B Out compliant transponder, and the response to our new product has been exceptionally positive seeing as the price includes a GPS source and encoder as one neat lightweight package…
Hope this helps
Cheers
George Pesce
Group General Manager
Microair Avionics and Intelligent Transport Systems