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#31
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why is intercept altitude labeled "LOC only"?
"Sam Spade" wrote in message
... But, the two altitude designations when they are the same is incorrect, redundant, and has the potential for some confusion. I agree that it's redundant, confusing, contrary to the chart-design rules, and shouldn't be done. My only point is that at least nothing in the SWF ILS 9 chart is overtly false (whereas the LOC-only annotation for the GS-intercept altitude in the ASH ILS 14 chart is indeed false; if it were true, there'd be no specified GS-intercept altitude for the ILS approach). --Gary |
#32
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why is intercept altitude labeled "LOC only"?
Gary Drescher wrote:
"Sam Spade" wrote in message ... But, the two altitude designations when they are the same is incorrect, redundant, and has the potential for some confusion. I agree that it's redundant, confusing, contrary to the chart-design rules, and shouldn't be done. My only point is that at least nothing in the SWF ILS 9 chart is overtly false (whereas the LOC-only annotation for the GS-intercept altitude in the ASH ILS 14 chart is indeed false; if it were true, there'd be no specified GS-intercept altitude for the ILS approach). --Gary Yes, one is bad, the other is worse. ;-) |
#33
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why is intercept altitude labeled "LOC only"?
Sam Spade wrote:
Here is what is said in the original issuance of 8260.19C, dated 9/16/93 ( Page 8-11, Paragraph 811 d.): (1) Fix altitudes established on ILS for LOC-only should be coincident with the glide slope when possible. Where the stepdown fix altitude is not within 20 feet of the glide slope, annotate it for LOC use as follows: MIN ALT CAROL 1600^ *LOC ONLY This is the same as it reads today, for all practical purposes. Can you cite the language that changed this for some period between late 1993 and today? The language is the NOTE that was added in change 1 to clarify that if the glideslope intercept altitude and LOC altitude at the FAF are the same, then you only publish the one altitude. The above language says "within 20 ft of the glideslope" and not "within 20 ft of the glideslope intercept altitude". On the ASH ILS Rwy 14 procedure, although the glideslope intercept altitude is 1800, the actual glideslope altitude at CHERN LOM is 1586, which is more than 20 ft different than the LOC alt at CHERN LOM of 1800. Since the fix altitude of 1800 was not within 20 ft of the glideslope at CHERN LOM, the procedure specialist added "1800 LOC ONLY" on the FAA procedure form in addition to the 1800 glideslope intercept altitude. Both altitudes should have been shown (as they are at SWF) but only one was charted. The FAA form for this particular procedure was done before the clarification came out. Actually, the 20 ft part of this paragraph really only applies to stepdown fixes inside the LOC FAF, these days if the glideslope altitude at the LOM was 1750, and the glideslope intercept altitude and LOC altitude at the LOM was 2000, you still wouldn't show a "LOC ONLY" altitude at the FAF, even though the paragraph mentions "20 ft". However, if the stepdown altitude inside the LOC FAF (which only applies to LOC procedures) is not within 20 ft of the glideslope altitude at the stepdown fix, you have to add the "LOC ONLY" annotation to avoid the potential for someone on the glideslope thinking they have to stop descent until they pass the stepdown fix. The added NOTE is what applies to the altitudes outside the FAF. JPH |
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