eckhard - thanks for the reply. Your exactly right; the RTOW chart is runway / A/c config. (flaps, anit-ice, air-cond. etc.) specific, with wind across the top and tmeperature increasing downward.
It makes sense that when the temperature increases, the RTOW decreases, and so the V-speeds decrease; but the increase and then decrease of the V-speeds around the thrust break temperature is the one I can't quite work out - any ideas?
Cheers,
l5otg