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 less common in the U.S. but are important for RNAV (GPS) approaches when LPV is unavailable due to signal quality issues (e.g., solar storms) or lack of WAAS infrastructure.
Pilots must actively monitor GPS annunciators for the authorized minimums (e.g., LPV, LNAV/VNAV, LNAV), as insufficient satellite signal quality can cause automatic downgrades to a less precise approach.
Flying an LNAV/VNAV approach requires adhering to a fixed +/- 75-foot vertical window, indicated by a magenta pentagon between white lines, which differs significantly from the angular, progressively sensitive vertical guidance of an LPV approach.

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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.