In aviation, Vertical NAVigation is an autopilot function which directs the vertical movement of an aircraft (i.e. gains or losses in its altitude) while cruising and/or on approach to landing.
If used while cruising, VNAV causes an aircraft to climb or descend according to a pre-programmed FMS (flight management system) flight plan. The first aircraft to feature this use were Boeing 757 and 767 airliners in 1982.
When used on approach to landing, VNAV follows an ILS (instrument landing system) glideslope toward the runway. This process is known as "autoland" and has been available since the mid-twentieth century.
LNAV · RNAV · Navigation