why is intercept altitude labeled "LOC only"?

On Fri, 22 Sep 2006 23:16:31 GMT, Sam Spade wrote:

Thus the LOC FAF altitude and the GS intercept altitude differ more
than 20' and the note would be appropriate. What specifically am I
missing?

Let's say the G/S intercept altitude at ASH was 1,900 and the LOC
crossing altitude was 1,800. In that case the note would be correct.

Yea, light dawned - I was thinking about the difference in altitude
would be crossing the LOM depending on whether you'd be flying the ILS
or LOC.

Thanks.

Gary Drescher wrote:


Right, but if NACO wants to say "LOC only" it should be for a separate
specification of 1800', not for the (sole) one that's designated as the
intercept altitude. For example, in SWF ILS 9, there's a 2100' intercept
altitude, and separately from that there's a minimum altitude of 2100'
specified for the approach segment leading up to the OM; the latter altitude
is marked "LOC only".

http://www.naco.faa.gov/d-tpp/0610/00450I9.PDF

So the SWF chart seems right, but not the ASH chart.

--Gary


You're correct.
It appears that at the last time the procedures had a major revision,
the criteria in effect at the time (FAAO 8260.19 previous amendment)
required both the GS INTCP altitude AND the LOC altitude to be
published, even if they were the same altitude (one for GS INTCP and
another for LOC ONLY). The SWF chart is correct for that time period.
The ASH chart had both altitudes listed on the form that was submitted
for publication, but they were incorrectly combined on the plate into
one altitude entry, instead of 2 separate altitude entries, which could
be confusing. (The SWF altitudes don't cause the same confusion since
both altitudes are depicted). Since both altitudes are not depicted on
the ASH chart, there will be a NOTAM next week to remove the annotation
"* LOC ONLY". This will put it in compliance with the newer criteria
that only calls for 2 altitudes when the altitudes differ.
Any newer procedures will only have "LOC ONLY" altitude shown if it
differs from the GS INTCP altitude.

JPH

"Sam Spade" wrote in message
...
Gary Drescher wrote:
Right, but if NACO wants to say "LOC only" it should be for a separate
specification of 1800', not for the (sole) one that's designated as the
intercept altitude. For example, in SWF ILS 9, there's a 2100' intercept
altitude, and separately from that there's a minimum altitude of 2100'
specified for the approach segment leading up to the OM; the latter
altitude is marked "LOC only".

http://www.naco.faa.gov/d-tpp/0610/00450I9.PDF

So the SWF chart seems right, but not the ASH chart.

That chart is wrong, too.

Ok, but at the SWF chart makes sense. It's wrong only in that the extra,
LOC-only altitude is superfluous.

--Gary

"Sam Spade" wrote in message
...
Right, but if NACO wants to say "LOC only" it should be for a separate
specification of 1800', not for the (sole) one that's designated as the
intercept altitude. For example, in SWF ILS 9, there's a 2100' intercept
altitude, and separately from that there's a minimum altitude of 2100'
specified for the approach segment leading up to the OM; the latter
altitude is marked "LOC only".

http://www.naco.faa.gov/d-tpp/0610/00450I9.PDF

So the SWF chart seems right, but not the ASH chart.

That chart is wrong, too.

Ok, but at least the SWF chart makes sense. It's wrong only in that the
extra, LOC-only altitude is superfluous.

--Gary

Gary Drescher wrote:
"Sam Spade" wrote in message
...

Gary Drescher wrote:

Right, but if NACO wants to say "LOC only" it should be for a separate
specification of 1800', not for the (sole) one that's designated as the
intercept altitude. For example, in SWF ILS 9, there's a 2100' intercept
altitude, and separately from that there's a minimum altitude of 2100'
specified for the approach segment leading up to the OM; the latter
altitude is marked "LOC only".

http://www.naco.faa.gov/d-tpp/0610/00450I9.PDF

So the SWF chart seems right, but not the ASH chart.


That chart is wrong, too.


Ok, but at the SWF chart makes sense. It's wrong only in that the extra,
LOC-only altitude is superfluous.

--Gary


Why does it make sense?

JPH wrote:

Gary Drescher wrote:


Right, but if NACO wants to say "LOC only" it should be for a separate
specification of 1800', not for the (sole) one that's designated as
the intercept altitude. For example, in SWF ILS 9, there's a 2100'
intercept altitude, and separately from that there's a minimum
altitude of 2100' specified for the approach segment leading up to the
OM; the latter altitude is marked "LOC only".

http://www.naco.faa.gov/d-tpp/0610/00450I9.PDF

So the SWF chart seems right, but not the ASH chart.

--Gary


You're correct.
It appears that at the last time the procedures had a major revision,
the criteria in effect at the time (FAAO 8260.19 previous amendment)
required both the GS INTCP altitude AND the LOC altitude to be
published, even if they were the same altitude (one for GS INTCP and
another for LOC ONLY). The SWF chart is correct for that time period.
The ASH chart had both altitudes listed on the form that was submitted
for publication, but they were incorrectly combined on the plate into
one altitude entry, instead of 2 separate altitude entries, which could
be confusing. (The SWF altitudes don't cause the same confusion since
both altitudes are depicted). Since both altitudes are not depicted on
the ASH chart, there will be a NOTAM next week to remove the annotation
"* LOC ONLY". This will put it in compliance with the newer criteria
that only calls for 2 altitudes when the altitudes differ.
Any newer procedures will only have "LOC ONLY" altitude shown if it
differs from the GS INTCP altitude.

JPH

It never made sense to publish two altitudes when they are both the
same. My recollection was the policy used to be the same as it now is.
There may have been an interim period where it was changed to publish
both, even though they are the same, and now it has been corrected to
what it was for many years.

It is very confusing to have 2100 and 2100, for example.

"Sam Spade" wrote in message
...
Gary Drescher wrote:

In the NACO plate for ASH ILS 14, the GS intercept altitude (1800') is
labeled "LOC only". How can a GS intercept altitude apply to the LOC
approach and not to the ILS approach? Is this a charting error?

http://www.naco.faa.gov/d-tpp/0610/05036I14.PDF


The note is a mistake. That note is supposed to appear only when the G/S
intercept altitude and the LOC FAF crossing altitude differ by more than
20 feet.

Thanks! But what happens if they differ by only 20'? Is the LOC altitude
then not designated "LOC only"? Or is the LOC altitude omitted altogether? I
don't quite see the rationale for either.

The procedure will be corrected by NOTAM sometime next week (or so they
say. ;-)

Great! (I'd also emailed NACO, but their only reply so far is that they're
looking into it.)

--Gary

"Sam Spade" wrote in message
...
Gary Drescher wrote:
"Sam Spade" wrote in message
...

Gary Drescher wrote:

Right, but if NACO wants to say "LOC only" it should be for a separate
specification of 1800', not for the (sole) one that's designated as the
intercept altitude. For example, in SWF ILS 9, there's a 2100' intercept
altitude, and separately from that there's a minimum altitude of 2100'
specified for the approach segment leading up to the OM; the latter
altitude is marked "LOC only".

http://www.naco.faa.gov/d-tpp/0610/00450I9.PDF

So the SWF chart seems right, but not the ASH chart.

That chart is wrong, too.

Ok, but at least the SWF chart makes sense. It's wrong only in that the
extra, LOC-only altitude is superfluous.

Why does it make sense?

Because the chart has two altitude designations, and one of those
designations applies only to LOC approaches (and is thus to be ignored when
flying an ILS approach). It's just that the LOC-only altitude is superfluous
in this case, because the (identical, in this case) GS-intercept altitude
already serves as the LOC-approach altitude too (unless otherwise noted).

--Gary

JPH wrote:
Gary Drescher wrote:


Right, but if NACO wants to say "LOC only" it should be for a separate
specification of 1800', not for the (sole) one that's designated as
the intercept altitude. For example, in SWF ILS 9, there's a 2100'
intercept altitude, and separately from that there's a minimum
altitude of 2100' specified for the approach segment leading up to the
OM; the latter altitude is marked "LOC only".

http://www.naco.faa.gov/d-tpp/0610/00450I9.PDF

So the SWF chart seems right, but not the ASH chart.

--Gary


You're correct.
It appears that at the last time the procedures had a major revision,
the criteria in effect at the time (FAAO 8260.19 previous amendment)
required both the GS INTCP altitude AND the LOC altitude to be
published, even if they were the same altitude (one for GS INTCP and
another for LOC ONLY). The SWF chart is correct for that time period.
The ASH chart had both altitudes listed on the form that was submitted
for publication, but they were incorrectly combined on the plate into
one altitude entry, instead of 2 separate altitude entries, which could
be confusing. (The SWF altitudes don't cause the same confusion since
both altitudes are depicted). Since both altitudes are not depicted on
the ASH chart, there will be a NOTAM next week to remove the annotation
"* LOC ONLY". This will put it in compliance with the newer criteria
that only calls for 2 altitudes when the altitudes differ.
Any newer procedures will only have "LOC ONLY" altitude shown if it
differs from the GS INTCP altitude.

JPH

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?

Gary Drescher wrote:

"Sam Spade" wrote in message
...

Gary Drescher wrote:

"Sam Spade" wrote in message
. ..


Gary Drescher wrote:


Right, but if NACO wants to say "LOC only" it should be for a separate
specification of 1800', not for the (sole) one that's designated as the
intercept altitude. For example, in SWF ILS 9, there's a 2100' intercept
altitude, and separately from that there's a minimum altitude of 2100'
specified for the approach segment leading up to the OM; the latter
altitude is marked "LOC only".

http://www.naco.faa.gov/d-tpp/0610/00450I9.PDF

So the SWF chart seems right, but not the ASH chart.

That chart is wrong, too.

Ok, but at least the SWF chart makes sense. It's wrong only in that the
extra, LOC-only altitude is superfluous.


Why does it make sense?


Because the chart has two altitude designations, and one of those
designations applies only to LOC approaches (and is thus to be ignored when
flying an ILS approach). It's just that the LOC-only altitude is superfluous
in this case, because the (identical, in this case) GS-intercept altitude
already serves as the LOC-approach altitude too (unless otherwise noted).

--Gary


But, the two altitude designations when they are the same is incorrect,
redundant, and has the potential for some confusion.