In the UK it's a legal requirement to readback any executive instruction and I'd take that to be the next ATSU and frequency. More importantly I'd want the repliers callsign. Just listen to how many pilots on a busy frequency don't give their callsign! Has the ATCO got a video link so he can see your lips move? Not yet! With a busy frequency and 10 flights on the R/T how can I tell which flight is replying; the radar target doesn't light up gents! Let's cut out the sloppiness and do things right.
