RNAV approach with LP+V guidance

Ride along as I fly the RNAV (GPS) RWY 05 approach at Sanderson Field southwest of Seattle. You’ll see Garmin SmartCharts in action and a HUD-like display of key flight instruments created from data downloaded from my panel and produced with the tools at FlySto.net. I joined this VFR practice approach from the southeast to remain well clear of the busy skydiving operation at the airport. That entry required flying the HILPT at ULESS, as shown on the standard FAA chart. This RNAV (GPS) approach at Sanderson has another feature that often confuses IFR pilots—LP, or localizer performance, minimums. When LP minimums are published, a WAAS-capable navigation system creates a localizer-like path that funnels you to the runway. That narrowing course can provide lower minimums because it avoids terrain and obstacles that lie within the constant width lane established for approaches with only LNAV minimums. Most newer systems also create an advisory +V glidepath to help you fly a smooth descent. But LP minimums are still a 2D, nonprecision approach to an MDA. You must not confuse flying to the LP line of minimums with a +V advisory glidepath, displayed as LP+V, with the LPV minimums on a 3D, precision approach with approved vertical guidance to a DA. That critical distinction is clearer on the Garmin SmartCharts version of the approach chart than on the old FAA format, in part because Garmin uses color to help you quickly identify an advisory GP and how it relates to the MDA. When flying a +V advisory glidepath, you cannot descend below the MDA unless you have the runway environment in sight as required by FAR 91.175. Remember also that an AP or FD does not distinguish between advisory and approved vertical glidepaths, and you must intervene to stop the descent at the MDA unless you can continue visually to the runway. Now join me in the A36 as I fly the scenic VFR Blake departure from runway 32L at Boeing Field and turn westbound toward Shelton.