The system can provide navigation guidance for GPS and NAVAID instrument approach procedures. Visual Approach guidance is also available. This section will discuss loading, activating, and removing approaches designated for navigation. See the Flight Instruments section for information on Changing The Navigation Source of the CDI, and for information on the Vertical Deviation Indicator on the PFW. Refer to NAV Receiver Tuning in the Audio and CNS Section for information on selecting and tuning a NAV receiver. See the AFCS Section for information on Lateral Modes and Vertical Modes used for approach guidance.