LNAV LPV LNAV/VNAV GPS or RNAV (GPS) Approach Waypoints Flying a GPS or RNAV (GPS) Approach LNAV (lateral navigation), like a conventional localizer,  provides lateral approach course guidance. LNAV minimums  permit descent to a prescribed minimum descent altitude  (MDA). The LNAV procedure shown on the chart in  Figure 3-48  offers an MDA of 1,620 feet. LNAV/VNAV (lateral navigation/vertical navigation)  equipment is similar to ILS in that it provides both lateral  and vertical approach course guidance. Since precise vertical  position information is beyond the current capabilities of  the global positioning system, approaches with LNAV/ VNAV minimums make use of certified barometric VNAV  (baro-VNAV) systems for vertical guidance and/or the  wide area augmentation system (WAAS) to improve GPS  accuracy for this purpose. (Note: WAAS makes use of a  collection of ground stations that are used to detect and  correct inaccuracies in the position information derived from  the global positioning system. Using WAAS, the accuracy  of vertical position information is increased to within 3  meters.) To make use of WAAS, however, the aircraft must  be equipped with an IFR approved GPS receiver with WAAS  signal reception that integrates WAAS error correction  signals into its position determining processing. The WAAS  enabled GPS receiver shown in  Figure 3-49  allows the pilot  to load an RNAV approach and receive guidance along the  lateral and vertical profile shown on the approach chart in  Figure 3-48. LPV can be thought of as “localizer performance with  vertical guidance.” Procedures with LPV minimums use GPS  information to generate lateral guidance, and IFR‑approved  GPS/WAAS receivers to generate vertical guidance similar  to an ILS glideslope. Several manufacturers now offer FMS/ GPS RNAV units capable of flying approaches to LPV  minimums. Figure 3-50  shows a GPS approach loaded into an FMS/GPS  RNAV. As previously noted, approaches must be selected  from a specific approach menu in the FMS. The software  then loads all of the waypoints associated with that procedure  from the database into the flight route. It is not possible for  you to enter or delete, separately or individually, waypoints  associated with the approach procedure. Once loaded, a GPS or RNAV (GPS) approach is shown in  the FMS display as a collection of waypoints with a title that  identifies the approach. Four waypoints in every approach  procedure have special designations: (1) initial approach  waypoint; (2) final approach waypoint; (3) missed approach  waypoint; and (4) missed holding waypoint. Most FMS require the pilot to choose whether to simply  load, or load and activate, instrument approach procedures.  When ATC tells you to expect a certain approach, select  that approach from the menu and load it into the flight plan.  Loading an approach adds its component waypoints to the  end of the flight plan, but does not make them active. Once  ATC clears you for the approach (or, alternatively, begins  providing radar vectors to intercept the final approach  course), you must remember to activate the approach to  receive course guidance and auto‑sequencing. You must be  careful not to activate the approach until cleared to fly it,  however, since activating the approach will cause the FMS  to immediately give course guidance to the initial approach  It is very important to know what kind of equipment is  installed in an aircraft, and what it is approved to do. It is  also important to understand that the VNAV function of  non‑WAAS‑capable or non‑WAAS‑equipped IFR approved  GPS receivers does not make the aircraft capable of flying  approaches to LNAV/VNAV minimums. GPS ENR FLAGGED 119.000 121.600 114.10 116.00 1200 A  C  T A  C  T S  B  Y S  B  Y S  B  Y --.- vor MSG PROC FPL NAV ETE GS DIST BRG 120 kt 04:52 9.74 n m 332° TRK 332° Lnav/Vnav C345 SUNOL RW34Lm DTK 346° This FMS/RNAV provides lateral and vertical  guidance during an RNAV approach. RNG PULL SCAN PUSH ON BRT PROC CRSR MSG OBS ALT NRST CLR ENT D MENU OBS 285 TK 0.1nm QUADSi LEG APT VOR NDB INT USR ACT NAV 1 FPL SET AUX 0.1 nm Initial approach waypoint Final approach waypoint Missed approach waypoint Missed hold waypoint Figure 3-50. Approach waypoints. Figure 3-49. WAAS data provides lateral and vertical guidance. 3-35