Although they look alike, there is a world of difference between ILS, LNAV+V and LNAV/VNAV glidepaths. It turns out that not all glidepaths are created equal.
Advisory glidepaths on non-precision approaches (e.g., LNAV+V) are not guaranteed clear of obstacles below the Minimum Descent Altitude (MDA), unlike precision approaches.
Pilots often mistakenly follow these advisory glidepaths below MDA, posing a safety risk due to a lack of obstacle clearance.
The FAA is removing Visual Descent Angle (VDA) information from some approaches to prevent the display of these potentially misleading glidepaths.
While Continuous Descent Final Approaches (CDFA) are beneficial, Part 91 pilots must treat the MDA as a hard limit and are solely responsible for obstacle clearance below it.
In March, we examined the hazard of following a non-precision visual descent angle (VDA) below the MDA. This is easy to do because flying a non-precision approach with an advisory glidepath looks similar to an ILS, LPV or LNAV/VNAV with a real glidepath.
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