Max Trescott and Rob Mark talk about how pilots get into trouble when they misunderstand instrument procedures, mishandle a go-around, or make shockingly poor decisions on the ground and in the air. They open with Max’s request from the NTSB for a phone call to share his knowledge with them of advisory glidepath guidance, the “+V” vertical path shown on some nonprecision approaches. That leads to a sharp discussion by Max and Rob of why advisory glidepaths can become traps when pilots confuse lateral navigation plus vertical guidance (LNAV+V) or localizer performance plus vertical guidance (LP+V) with true precision-style guidance and fail to respect minimum descent altitude (MDA) limits.
The team first discusses a recent accident in which the pilot of N58544, a Cessna 182, took off from York, Pennsylvania, with a tow bar attached. Rob and Max share what they teach student pilots about the handling of tow bars to avoid these kinds of mishaps.
They then examine two preliminary reports. In Gulf Shores, Alabama, Beech A36 Bonanza N66519 crashes on approach in weather near minimums after weak radio reception, missed vectors, and a breakdown during the final phase of flight. Near Hartsburg, Missouri, Piper PA-46 Malibu Mirage N451MA breaks up in severe weather.
The final reports are just as revealing. Cirrus SR22 N272HM near Lake Elsinore, California, becomes a success story when the pilot encounters issues, wisely pulls CAPS, and survives. Cirrus SR20 N1108T in Key Largo, Florida, stalls during a go-around after a pilot error. The episode also includes a drunk certificated flight instructor’s (CFI) VFR-into-instrument meteorological conditions (IMC) Cessna 150 crash, a hand-propping accident in an RV-9, and a runaway Bellanca left idling on the ground with a non-pilot on board.
Regarding advisory glideslopes, it is imperative to know your own equipment and installation. You do that by shooting practice approaches in VFR of every kind of approach you can find to get familiar with your aircraft. In my RV-7 equipped with a GNS430W and Grand Rapids Technologies Sport EX, the advisory glideslope appears on RNAV approaches that feature LP minimums. I can’t inhibit it even if I don’t arm “GPSV” on the EX. I just ignore it and fly the step-downs to the MDA as if it were an LNAV-only approach.
The conditions for presentation of such guidance, buttonology related to it, and its appearance on your instruments can vary a lot depending on the brand and how the avionics shop configured the installation. Know your equipment!
In the discussion about +V, Max says that once reaching MDA, “You’re not allowed to descend further until one of three things is true…” I suspect Max misspoke, as I’m sure he knows that per 91.175(c), all three (not just one) of the following conditions must be met in order to operate below the DA/MDA: