Just to clarify, the only mode s transponder which I am aware of which will not comply with phase 3 is the garmin 328. There is no timescale for phase 3, but as I would expect 10 years plus from a new transponder I will get one which does comply. The TRT800 with the fix will be on my list but is not as easy to fit as the TRIG if you have an existing BK mode c. No plan to fit mode s for the time being though. We will know the result of the second consultation soon.
Rod1