Vertical navigation

In aviation, vertical navigation (VNAV, usually pronounced vee-nav) is glidepath information provided during an instrument approach, independently of ground-based navigation aids in the context of an approach and a form of vertical guidance in the context of climb/descent. An onboard navigation system displays a constant rate descent path to minimums. The VNAV path is computed using aircraft performance, approach constraints, weather data, and aircraft weight. The approach path is computed from the top of descent point to the end of descent waypoint, which is typically the runway or missed approach point.