One of the things I see often on IFR stage checks and IPCs is a lack of familiarity with the different kinds of GPS approaches and their respective capabilities and idiosyncrasies. Introduction of Localizer Precision (LP) approaches has made that worse. Given that the U.S. has over 12,000 GPS approaches, it’s time we mastered the variables.
GPS Alphabet Soup
Key Takeaways:
- The article identifies five types of GPS approaches—LNAV, LNAV+V, LP (non-precision with MDAs), LNAV/VNAV, and LPV (precision with DAs)—distinguished by their vertical guidance capabilities and precision.
- Wide Area Augmentation Service (WAAS) is essential for the enhanced accuracy and vertical guidance offered by LNAV/VNAV, LPV, and the newer LP approaches, enabling lower minimums and improved safety.
- LPV approaches provide the highest precision, with angular guidance and sensitivity comparable to an ILS, making them operationally equivalent to Category I ILS procedures without ground-based equipment.
- A key distinction is between advisory vertical guidance (like LNAV+V's mathematical glidepath, still non-precision) and certified WAAS-derived vertical guidance (LNAV/VNAV, LPV), with critical implications for obstacle clearance and minimum descent altitudes.
Key takeaways sponsored by Aviator Pro | Start Your Training ->
See a mistake? Contact us.
