Deadly Display Potential in the Cockpit

It's common misconception, but +V advisory glide slope isn't same as LPV glide path.

Max Trescott

Friday, June 26, 2026 at 08:00 AM ET

Verified

Edited By:

Travis Tingle

Level at MDA and don’t go lower until you can see the runway environment. [Credit: FlySto]

Key Takeaways:

Advisory glide slopes (+V) on RNAV non-precision approaches visually mimic fully protected LPV paths on PFDs but only provide obstacle protection down to the Minimum Descent Altitude (MDA), not below, which can lead to terrain collisions.
A fatal accident highlighted the dangerous misconception that autopilots coupled to advisory glide slopes will level off at MDA or that continued descent on this path below MDA is safe; autopilots will continue descent, and obstacle protection ceases at MDA.
Pilots must strictly adhere to FAR 91.175(c) visual reference requirements before descending below MDA, as advisory glide slopes offer no terrain clearance below this point, with subtle chart clues indicating potential hazards.

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Flying an RNAV (GPS) approach with a +V advisory glide slope looks and feels exactly like flying a glide path to LPV minimums. But while an LPV path is obstacle-protected down to a decision altitude (DA), a +V glide slope can run you through a mountain after you descend below the minimum descent altitude (MDA). Yet in both situations, the PFD display will look almost identical.

A recent fatal accident involving a 2024 Epic E1000 at Steamboat Springs, Colorado, highlights this issue. The E1000 is a capable six-place turboprop equipped with the latest NXi version of the Garmin G1000. While it’s early in the National Transportation Safety Board’s investigation, already much is known about what happened from ADS-B data.