Well..., the JCP proposal was to subsidise approx 11000 GA aircraft below 5700kg MTOW, which is a very high percentage of the total aviation fleet in Oz.
So., yeah.., it'll improve safety..., perhaps not as much as was claimed in the JCP, but an improvement non the less.
Biggles_in_Oz, the majority of the GA fleet already have transponders. My IFR aircraft also has a TAS fitted. Can you please explain to me how fitting yet another device to my aircraft will improve my safety in any way what-so-ever ? as Dick Smith wrote earlier, there is no quantifiable safety increase - just an extra system to maintain.
Remember we will still need the current transponders as a back up to the inevitable GPS failures - and if you doubt a terrorism event; think sunspots ... we are currently between major sun 'storms' so there is no current GPS interference from the sun (probably why the worlds cooling at the moment) though wait untill the sun turns on again
