[QUOTE][This is a misunderstanding I have seen time and time again (737). The function does nothing to prevent that./QUOTE]
BOAC
I agree with esr. It certainly used to help on the 737-700 from high levels because it only goes to IDLE at a lower level after intercepting the path from below at 1000 fpm so the initial descent at high level is not commenced so aggressively. I don't find it such a problem on the -800.
Also I remember Britannia using Descend Now on the 767 for a while (long time ago admittedly)and I seem to remember it was something to do with engine cooling.