I see, so all of the these three will be announced!
Is there a noticeable difference between LPV and LNA/VNAV if you fly it with the DFC90, or is it really more a “legal” thing (I know that the precision gets higher the closer you get with the LPV, but already the precision with my normal 430s was so high …)
Thank you!
JasonC wrote:
And no more RAIM checks.
That is too bad because the autorouter briefing pack now contains RAIM information for all airfields of your flight! All that advanced Kepler mathematics for nothing 
When the Jeppesen chart has a continuous descent line, then the GNS will have a +V.
Unless there is a BARO-VNAV approach in the database, but no LPV, in which case you get just LNAV
Unless that’s been fixed, but AFAIK nobody here is quite sure. Was Cambridge one problem case? @Bookworm will know.
Flyer59 wrote:
Is there a noticeable difference between LPV and LNA/VNAV if you fly it with the DFC90
I think it is noticeable if it is an approach to minimums you will end up spot on at DH. That increasing accuracy helps. But even LNAV+V is very accurate.
Unless that’s been fixed
It hasn’t.
It hasn’t.
Is there a list of airports where the +V glideslope is on the Jepp plates but cannot be flown for this reason because the GPS doesn’t present it?
AFAIK it isn’t just a legality issue (aircraft not certified for BARO-VNAV). The +V glideslope simply doesn’t appear. A lot of people have reported this at various airports. But whether this is a GPS config issue only I don’t know… my KLN94 came configured for VFR-only because the UK CAA insisted in 2002 that the new TB20 was a VFR aircraft 
Of course the dealer “fixed” that in 5 minutes…
The WAAS GPS only has one database definition for an RNAV (GPS) procedure if there are multiple sets of minimums published on the same chart. So if there is an LPV DA, LNAV/VNAV DA, and a LNAV MDA published, you will normally only see the system annunciate LPV. If the SBAS HPL or VPL is out of limits for the approach, it will be downgraded to LNAV without any vertical guidance. The downgrade happens 60 seconds prior to the FAF, although you will get some advance warning of this if you know what to look for. With a TSO C146 GPS, in the US, you can fly any of the charted procedures if you see the LPV annunciation, IOW you can fly the procedure to the LPV DA or to the LNAV/VNAV DA or to the LNAV MDA. The GNS430W annunciates the current mode/CDI mode of the navigator. When enroute, it annunciates ENR, when in the terminal mode, it annunciates TERM, and when the FAF is the next fix on the approach (VTF or just after you pass the IF), the GNS430W should annunciate the approach mode of LPV or L/VNAV or LNAV or LP or LNAV+V or LP+V depending on the approach. The annunciation is in Green background except when a downgrade is likely, in which case it is amber. The Amber color indicates that the HPL or VPL is not within tolerances for the approach and that a downgrade is likely. All downgrades are to LNAV without any vertical guidance. There are no downgrades from LPV to L/VNAV or LNAV+V.
As far as the software issue is concerned that was the cause of the restriction for vertical guidance on LNAV/VNAV or LNAV+V, it is resolved. That, however is independent of whether or not the state permits its usage or has the approaches coded in the database to permit the operation or not.
In the US, LNAV/VNAV is largely irrelevant to those who fly RNAV (GPS) approaches. In almost every case, the LPV has a lower DA than the LNAV/VNAV DA on the same procedure, although there are a small minority of exceptions. There are still a very few runways that are served where there is an LNAV/VNAV DA but not a LPV DA. The approach is flown identically to an LPV, so there is no special training required for these few exceptions. I tell my students to ignore the LNAV/VNAV. Most have never seen the annunciation after years of flying in the US.
Thank you. NCYankee … looking fwd to my first LPV this coming weekend!
When you load an approach using the GNS430W dialog, the expected annunciation is displayed in the lower corner of the dialog map. If it is LNAV, you won’t have advisory vertical guidance, if it is LNAV+V, you will. This can be used to determine if an approach has advisory vertical guidance, well before you actually fly the procedure.
Tip of the day: If you are concerned about a potential downgrade, go to the satellite page in the Nav group. Look at the parameter VFOM. It is the Vertical Figure of Merit and in units of feet. Anytime this value exceeds 60 feet, don’t expect any vertical guidance and do expect a fail down to LNAV. If your state provides for LPV with a DA below 250 feet, you will need to see the HFOM at 40 feet or less to avoid the likelihood of a fail down to LNAV.
Thanks for those detailed answers, NCYankee.
Is there some way to check the Jepp database (e.g. in Jeppview) to see which airports would have the BARO-VNAV problem? Or, what would such a plate look like?
