VNAV

In aviation, Vertical NAVigation is an autoflight function which directs the vertical movement of an aircraft (i.e. gains or losses in its altitude).

If used in the cruise, VNAV causes an aircraft to climb or descend according to a vertical elements of a pre-programmed FMS (flight management system) flight plan. The first aircraft to feature this use were Boeing 757 and 767 airliners in 1982.