Exploring the Corner Case Approach for a Pilot

Solar storm or poor signal quality can force a downgrade past minimums.

Max Trescott

Friday, August 28, 2026 at 08:00 AM ET

Verified

Edited By:

Travis Tingle

GA airplane approach point of view [Credit: FLYING Archive]

Key Takeaways:

LNAV/VNAV minimums are a less common type of GPS approach minimum in the U.S. but are standard in regions without WAAS infrastructure or are encountered when LPV approaches downgrade due to insufficient satellite signal quality.
Pilots must actively monitor their GPS receiver's annunciator (e.g., LPV, L/VNAV, LNAV) as approaches can automatically downgrade based on signal quality, requiring adaptability, as experienced by the author during a solar storm.
Flying an LNAV/VNAV approach involves a unique vertical guidance presentation using a magenta pentagon within a fixed 75-foot vertical window, distinct from the angular and progressively more sensitive guidance of LPV.

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LNAV/VNAV minimums are a bit of a mystery to most U.S. pilots. That’s probably because they’re rarely encountered, except at the relatively few airports with RNAV (GPS) approaches that have LNAV/VNAV minimums but no LPV minimums.

However, as will be explained, I encountered them while flying an approach with LPV minimums when the satellite signal quality was insufficient to support LPV minimums.