Garmin 80 User Newsletter page 4

Another example that is more subtle is the RNAV approaches to runway 19L at Wichita Mid-Continent. The plates are shown below.
The RNAV Y and Z 19L approach at KICT.
The new electronic database will have the RNAV Y approach embedded in it, although the current release of the paper chart indicates
the procedure is not in the database. Note the differences between the approaches from the FAF at KONYA to the runway. The Y
approach has an additional waypoint, HELUM, which is not embedded in the electronic database and can only be identified by the
distance to the runway. The vertical paths are also slightly different with the LNAV/VNAV approach set at 3 degrees and the
advisory vertical guidance set at 3.04 degrees.
Also be aware that the RNAV Z approach may be flown as either an LNAV/VNAV or LNAV approach, whereas the RNAV Y
approach is LNAV only.
There is another subtle issue at work with these two approaches, namely the LNAV MDA. By being able to identify HELUM a
substantially lower MDA can be obtained. In situations where WAAS is not available or VPL exceeds 50 meters (located on the SYS
page showing GPS performance data) vertical guidance will not be available. In those cases, selecting the RNAV Y approach would
be a better choice allowing a lower MDA. If sufficient performance to provide vertical guidance is not available, the RNAV Z
approach will be automatically downgraded as it is currently.
Please be aware when choosing RNAV approaches that these differences exist and the similarities between the approaches to the same
runway can be confusing. The primary difference in these would be the minimums associated with the approach and the fact that the
LPV minimum is a DA and the RNAV Y approach with or without advisory vertical guidance would be an MDA and treated
accordingly.
As we have emphasized in the past, reasonable care should be exercised when selecting and reviewing the approach prior to the IAF.