* 1% of the TAS is an approximtion of the Radius of Turn
It works well. Of course it's not perfect, but definately good enough for every day work. I taught it to students on semi-glass cockpits, and it worked well, on full FMC interceptions I find the automatic initiation of interception and my own mental calculation differ by no more than a few seconds.
Regarding the radius of turn of an A320 at 210 Kts, I don't have a calculator by my side, but I strongly suspect that it would be the same as that for a B747, A380, Lancaster, or Wright Flyer at 210 knots, provided that the bank angle was the same - sorry couldn't resist.
Regards,
Old Smokey