It provides lateral guidance from GPS and/or WAAS and vertical guidance from a barometric altimeter or WAAS. This is a non-WAAS approach down to an MDA, but your GPS unit may still give you a +V. LNAV/VNAV is also a non-precision approach. One other type of GPS approach that you will encounter is an LNAV approach. If you arrive at the MDA on the advisory glide path and the runway isn’t in sight, DON’T GO BELOW THE MDA! Most autopilots won’t level off at the MDA, even if that altitude is set in the altitude pre-select, so this will involve turning off the autopilot before the MDA and manually leveling off, or engaging the altitude mode of your autopilot at the MDA. Look out the windscreen and make sure you won’t hit anything. This AC applies to all operators conducting RNAV (GPS) approach procedures to LPV or LP lines of minima using WAAS navigation avionics under 14 CFR parts 91, 91 subpart K (part 91K), 121, 125, 129, 133, 135 and 137 within the U.S. Don’t just hone in on your instruments when you break out of the clouds. (2) WAAS equipment approved only for nonprecision approaches. The big thing I tell people is, when you arrive at the MDA and the runway is in sight, following the advisory glide path below the MDA could get you in trouble with obstacles. Again, the pilot/crew will be alerted to the loss of VNAV and shall revert to LNAV minimums. You can already fly LNAV/VNAV with a WAAS GPS, however in most cases you can also fly the LP/LPV minima, which if they exist will almost always be lower anyway. GPS/WAAS receivers can achieve position accuracy of a few meters across the NAS.

The GPS-like signal from the navigation transponder can also be used by the GPS/WAAS receiver as an additional source for calculation of the user's position. The kicker is obstacle clearance is not guaranteed and the pilot needs to keep an eye on minimum altitudes at the different waypoints on the approach. The GPS/WAAS receiver processes the WAAS augmentation message as part of position estimation. What does LP+V indicate? An advisory glide path is just advisory, but it is totally legal to follow down on a non-precision LP approach.

Do you need waas for lnav vnav