VNAV gives accurate vertical guidance for NDB, VOR, GNSS, RNP AR. The tolerances vary.
Doesn't matter whether you're flying an NDB, VOR, GNSS, ILS or RNP AR in a modern jet...keep the needles centred and you arrive safely at the minima.
Last edited by Chimbu chuckles; 27th Feb 2013 at 10:08.