Here's Why LNAV+V Isn't on Your Approach Plate | Advisory Glidepath | GPS Acronyms

GPS Acronyms are confusing, especially ones that can't even be found on approach plates like LNAV+V. Let's dive into that one in this video.

[marianol]

Under the CDFA criteria what's usually done is to add 50ft to the MDA, there you turn it into a DDA (Derived Decision Altitude). You can fly a continuous descent and if you don't see the runway, you can Go Around without going below the actual MDA. All airliner's FMCs usually have the Glide Path coded into de database, so even though the approach is LNAV only, it's flown using LNAV/VNAV with the CDFA criteria.

[nathanwildthorn]

Thank you for this one! 😊 Clarification is a wonderful thing. 👍

[camocamx]

LNAV+V advisory glidepath will not level you off at the MDA even with minimums set in the approach. you will need to set your bug at the MDA if using autopilot to level off, hope this helps!! I like to use vertical speed to help meet any step downs and get me down to MDA

[joewaltz]

Always a great job of explaining.
Not all receivers work the same in figuring out a +V. Even if a LPV approach is associated with a runway, the Garmin GTN's will add a +V if WAAS is not available (LPV needs WAAS). This can be noted in the naming of the approach when selected on the flight plan page. Simulate WAAS failure by turning it off. Don't know how other manufacturers handle this issue.

[glennwatson]

I’ve had lnav+v in Australia and we don’t have sbas active yet. So don’t think you need waas since we dont have it yet. This was with a g3x and 650 navigator.

[liquidintegrity]

My Garmin GFC 500 coupled with dual g5 and Garmin GNX 375 Waas capable is capturing the glide path nicely and following the descent step down nicely.. Sometimes I see the +V option in my GPS when in approach mode. Not always the GPS is smart enough to fly the step downs properly, I would not recommend flying it in case of a real IMC and I usually like to disconnect the autopilot before the final approach fix so I won’t get saturated by automation and focus on the approach.

[miket]

I could be wrong and happy to be corrected but I think approaches with L/VNAV DA and LNAV MDA minima published won’t let you have LNAV + V if say WAAS was not available and you don’t have an air data computer to give baro VNAV. This is so that you don’t (inadvertently) use the advisory Vertical guidance down to the L/VNAV DA minima.

[edcew]

As long as the glide path is above the minimum altitude for each segment of the approach, the synthetic glide path is safe. Moreover, what manufacturer would sell a device that could give hazardous, misleading information? I think you're missing something here...