To enable vertical navigation on the MD-11, follow these steps:
Check FMS:
Ensure all required data is entered into the Flight Management System (FMS), including the flight plan, cruising altitudes, descent and climb profiles.
Configure Navigation Mode:
Select navigation mode on the autopilot (AP) panel. Typically, this is done by adjusting the lateral (LNAV) and vertical (VNAV) navigation modes.
Activate VNAV:
Press the VNAV button on the autopilot panel to activate vertical navigation. This will allow the aircraft to follow the altitude and speed profile programmed into the FMS.