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GPS MAP for LOC/DME

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Instrument Rating

When you load the Garmin 430 for CRQ ILS or LOC/DME RWY 24, it references the MAP as RW24. 

So if you are flying just the LOC/DME, does this mean your MAP will be defined by 0.0 on your GPS (and not 0.9 DME as shown on the profile view)?

If I wanted to verify I was at HUSET intersection, would I have to add 1.8+1.5 NM (and not 4.2 DME as shown on the profile view)? This is because the MAP is defined as RW24 and not I-CRQ like a conventional DME unit. This seems like a cumbersome method to identify fixes...

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2 Answers



  1. Wes Beard on Feb 01, 2014

    So if you are flying just the LOC/DME, does this mean your MAP will be defined by 0.0 on your GPS (and not 0.9 DME as shown on the profile view)?

    Yes. The GPS distance always counts down to the next fix. In this case the MAP at the end of the runway will read 0.0 when over it.

    If I wanted to verify I was at HUSET intersection, would I have to add 1.8+1.5 NM (and not 4.2 DME as shown on the profile view)?

    Some FMS or GPS software does not display any waypoints inside the FAF to the MAP. If this the case for you, then you will need to add the distances of 1.8 and 1.5 to get 3.3. Notice you can also take 4.2 minus 0.9 (MAP) to get the same value.

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  2. John D Collins on Feb 02, 2014

    Also, in some approaches, the localizer MAP point is not at the threshold, but at a short distance from it (example 0.5 NM). The MAP is usually specified as a DME distance, so if the threshold was at 0.9 DME, in my example, the MAP might be at 1.4 DME. The GNS430 shows the MAP to be at the threshold, but the pilot must determine the actual MAP by calculating the distance to the threshold, in my example, the GPS would read 0.5 at the MAP.

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