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 approaches provide obstacle protection only down to the Minimum Descent Altitude (MDA), unlike LPV approaches which protect to a Decision Altitude (DA); continuing descent below MDA on a +V glide slope lacks terrain protection and can be dangerous.
A recent fatal accident at Steamboat Springs highlighted this issue, where an aircraft, likely on autopilot following an advisory glide slope, continued its descent below the MDA and impacted terrain.
Pilots must manually level off at the MDA on non-precision approaches and only descend further if visual references are met (per FAR 91.175(c)), as autopilots will continue descent on advisory glide slopes below MDA, and chart indications for obstacles below MDA are often subtle.

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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.