An Epic E1000, N98FK, crashed near Steamboat Springs, Colorado during a night RNAV (GPS) approach. The lateral track was almost perfect, but the vertical profile was fatal: the airplane remained on an LNAV+V "advisory glide slope" and descended below the 9,100-foot MDA into terrain.

Max explains what Garmin calls Advisory Vertical Guidance, why LNAV+V can look nearly identical to an LPV on the PFD, and why it does not provide obstacle protection below minimums. He shows the airplane crossed the FAF MABKY and stepdown fix WDCHK essentially on altitude—then continued descending instead of leveling at MDA.

Max reviews the three requirements in 91.175(c) for descending below an MDA, explains why many autopilots will fly any coupled glidepath right through minimums unless you intervene, and decodes chart warnings like "Visual Segment – Obstacles" / "34:1 is not clear." He also shares his own simulator experience flying the RNAV (GPS) Z RWY 32 at KSBS and hitting the same mountain when the autopilot was coupled to the advisory glidepath.

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