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2 Answers

Loading LOC/GPS Approaches Into Garmin 430.

Asked by: 588 views FAA Regulations, Instrument Rating

Hello Everyone, 
Have you ever noticed that when you load any approach, other than RNAV approach, you get "GPS guidance is for monitoring only. Load approach?" message? 
I was under the impression that you could still legally load a localizer approach to use the along track distance (ATD) readout per AIM 1-2-3, GPS in lieu of DME. 
However, recently I was told that you can't do that because you are using the distance of a non RNAV approach past the FAF. I was pointed to the Garmin manual which states:
The navigation equipment required to join and fly an instrument
approach procedure is indicated by the title of the procedure and
notes on the IAP chart. Navigating the final approach segment (that
segment from the final approach fix to the missed approach point) of
an ILS, LOC, LOC-BC, LDA, SDF, MLS, VOR, TACAN approach,
or any other type of approach not approved for GPS, is not authorized
with GPS navigation guidance. GPS guidance can only be used for
approach procedures with GPS or RNAV in the procedure title.
 ( Page 10 of the Garmin manual-190-00356-03)
Since on a localizer approach does not have RNAV or GPS in the title you would have to use the Direct-to function and use I-PYM, for example, to get the proper and legal DME distance. 
What are your thoughts? Is the “guidance” part of the statement meant for course only or also DME/fixes?  

2 Answers

  1. KDS on Jan 16, 2018

    You just need to be monitoring the approach using the associated navigational instrument. There is nothing wrong with having the GPS tuned to the approach as an additional aid. It’s a bit like saying that just because you’re on an instrument approach doesn’t mean you cannot look out of the window too.

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  2. Best Answer

    John D Collins on Jan 17, 2018

    The prohibition on using GPS on an ILS is for the lateral guidance only, not the ATD provided by a DME. In the case of ILS or LOC/DME RWY 6 at KPYM, all the waypoints are named except for the threshold. Garmin includes two procedures in their database, one that is just the ILS and the other for the LOC/DME option where the stepdown fix ZASID is identified. The runway threshold is identified in both Garmin and Jeppesen versions of the database. So with the Garmin database, all the waypoints are named if you use the LOC/DME procedure. With the Jeppesen database, ZASID is not identified, but can be determined when at 1.5 NM from RW06 is displayed as the distance remaining to the threshold.

    Here is an excerpt the wording of the AIM, section 1-2-3 (c) Uses of Suitable RNAV systems:

    1. Determine aircraft position relative to, or distance from a VOR (see NOTE 6 below), TACAN, NDB, compass locator, DME fix; or a named fix defined by a VOR radial, TACAN course, NDB bearing, or compass locator bearing intersecting a VOR or localizer course.

    6. For the purpose of paragraph c, “VOR” includes VOR, VOR/DME, and VORTAC facilities and “compass locator” includes locator outer marker and locator middle marker

    BUVKE, AYEDE, and FREDO are named fixes and included in all the approach databases. ZASID is also a named fix whose location can be displayed on the moving map during an approach if one sets the map scale appropriately. The runway threshold is named RW06 in the database. ZASID is located 0.5NM + 1.0 NM =1.5 NM from RW06, as determined by the chart. It can also be determined from the distance to IPYM of 0.9 NM or using ZASID as a direct-to fix. In any case, the raw localizer course needs to be displayed in the primary view of the pilot on a CDI/HSI and used for lateral guidance on the final approach segment.

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