forums.flyimc.com : Advanced Instrument Training Forums > Avionics > Garmin 430/530 Forum > What does "D239Y" mean as a waypoint?
forums.flyimc.com : Advanced Instrument Training Forums > Avionics > Garmin 430/530 Forum > What does "D239Y" mean as a waypoint? |
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rkaplan Administrator 
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Attached is a screenshot from loading the KMSO ILS 11 in the Garmin 430/530. Among the initial approach fix choices are D239Y and D340Y. What do these mean? (Answer in following post.) Attachment: msoils11.jpg (Downloaded 54 times) |
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rkaplan Administrator
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rkaplan wrote: Attached is a screenshot from loading the KMSO ILS 11 in the Garmin 430/530. D239Y means the 25 DME fix on the 239 radial. D340Y means the 25 DME fix on the 340 radial. The trick to understanding this nomenclature is that Y is the 25th letter of the alphabet. |
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rjq Member
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rkaplan wrote: D239Y means the 25 DME fix on the 239 radial. D340Y means the 25 DME fix on the 340 radial. The trick to understanding this nomenclature is that Y is the 25th letter of the alphabet. So I've seen this a number of times now; the position of the letter being equal to the DME mileage. Is there nothing over 26NM, or if there is/are, how are those notated? Ron Q. |
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rkaplan Administrator
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rjq wrote: So I've seen this a number of times now; the position of the letter being equal to the DME mileage. Is there nothing over 26NM, or if there is/are, how are those notated? Hi Ron. Naming of waypoints including DME waypoints is governed by the ARINC 429 standard. If a DME waypoint distance were over 26NM then an alternate waypoint name would be created as you can read in detail in the Chelton EFIS Appendix here: http://www.cheltonflightsystems.com/PDFs/50BPilotsGuide/8-Appendix-Index.pdf Look in particular at pages 8-53 and 8-41. |
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rjq Member
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Hi Ron. Naming of waypoints including DME waypoints is governed by the ARINC 429 standard. If a DME waypoint distance were over 26NM then an alternate waypoint name would be created as you can read in detail in the Chelton EFIS Appendix here: http://www.cheltonflightsystems.com/PDFs/50BPilotsGuide/8-Appendix-Index.pdf Look in particular at pages 8-53 and 8-41. Thanks Richard, Found some info close to the pages you suggest. Can't say I have access to the ARINC standards, don't like the $$$ and haven't found any public domain reprints. The Chelton naming conventions did remind me I've seen something similar before, just didn't remember. Getting old; CRS. So it would appear we wouldn't see the generic Dxxx{A-Z} format, but a new (named) waypoint would be created instead. Thanks again for the forums. Ron |
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