VNAV
From Wikipedia, the free encyclopedia
Vertical NAVigation in aviation is a function of autopilot which directs vertical movement of aircraft either according to pre-programmed FMS flight plan during cruise or according to ILS glideslope during approach.
VNAV was first introduced on B757 and B767 in 1982.
See also: LNAV, Navigation.
More info on VNAV: http://www.ae.gatech.edu/people/jpclarke/cda/workshop2/presentations/Miller.pdf