Garmin Alert Cautions Pilots about Descent Below MDA

Garmin issued a service alert on Thursday that reminds pilots to follow instrument approach procedure minimum descent altitude (MDA) limits when flying an approach with advisory vertical guidance. These approaches are identified by a “+V” indication on primary flight displays.

While the alert doesn’t mention the February 13 crash of an Epic E1000 on approach to Colorado’s Steamboat Springs Airport (KSBS), this accident raised questions about the importance of not following the advisory glide path below the MDA unless the required runway environment is in view.

According to the service alert, “Garmin avionics may display advisory vertical guidance (+V) during certain nonprecision instrument approaches. Advisory vertical guidance provides vertical path information only and does not provide obstacle or terrain clearance assurance in the visual segment of an approach. Although advisory vertical guidance can assist with maintaining a glide path angle that complies with altitude restrictions, it remains the pilot’s responsibility to fly in strict compliance with the published approach procedure.”

“While an advisory glide path indication may be displayed, this guidance must not be flown below the published MDA without having met the conditions prescribed in FAR 91.175.

“Advisory vertical guidance is intended to assist with continuous descent final approach technique but does not change approach classification or minima and must not be relied upon for obstacle or terrain clearance, particularly in the visual segment of the approach.”