why is intercept altitude labeled "LOC only"?

[Gary Drescher]

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

--Gary

[John R. Copeland]

"Gary Drescher" > wrote in message ...
> 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
>
> --Gary
>
Maybe a little ambiguous, instead of a full-blown error.
The note applies to the "1800 ft", not to the glide-slope intercept.

Jeppesen clearly shows 1800 ft to the marker for the LOC approach,
whereas the ILS intercepts the glide path well outside the marker.
Without GS, you won't go below 1800 ft until reaching the marker.

[JPH]

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
>
> --Gary
>
>
It appears that someone got carried away with the "LOC ONLY". This
procedure has the same glideslope intercept altitude and LOC FAF
crossing altitude. The LOC ONLY annotation should only be there if the 2
altitudes are not the same. Last FLIP cycle had it the same way, so I'm
sure AVN-110 will check into why it's there and take whatever action is
needed to correct it.

JPH

[Gary Drescher]

"John R. Copeland" > wrote in message
...
>"Gary Drescher" > wrote in message
...
>> 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
>
>Maybe a little ambiguous, instead of a full-blown error.
>The note applies to the "1800 ft", not to the glide-slope intercept.

But on the NACO plate, 1800' *is* the glide slope intercept altitude (it's
so designated by the zig-zag arrow from the "1800" to the intercept point).

> Jeppesen clearly shows 1800 ft to the marker for the LOC approach,
> whereas the ILS intercepts the glide path well outside the marker.
> Without GS, you won't go below 1800 ft until reaching the marker.

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

[Tim Auckland]

On Thu, 21 Sep 2006 21:44:28 -0400, "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
>
>--Gary
>

Good question. It'll be interesting to see what others say.

There are a couple of other oddities on this plate which struck me:

a) MUGGY is shown as an IAF, but the plate doesn't show how to locate
it. I'm assuming it's on the relevant low-altitude chart, but is
it common for plates to omit this information?

b) The procedure turn altitude is 1600 ft. above the intercept
altitude. The way I normally fly procedure turns (1-minute legs in a
C172) I'd have to do a substantial dive when procedure turn inbound to
get below the glide slope for intercept. Is this amount of altitude
difference common?

Tim.

[Jose[_1_]]

> b) The procedure turn altitude is 1600 ft. above the intercept
> altitude. The way I normally fly procedure turns (1-minute legs in a
> C172) I'd have to do a substantial dive when procedure turn inbound to
> get below the glide slope for intercept. Is this amount of altitude
> difference common?

I suppose that depends on terrain and other traffic conditions. I've
seen it before. Remember, you can gou out quite a bit farther before
making the procedure turn, allowing a shallower descent. You need to
remain within 10NM (presumably of the LOM), but that's plenty of
distance to descend from 3400 to zero, picking up the GS from underneath
on the way.

Jose
--
"Never trust anything that can think for itself, if you can't see where
it keeps its brain." (chapter 10 of book 3 - Harry Potter).
for Email, make the obvious change in the address.

[rps]

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
>

It's either a charting error or the feds are trying to save ink. The
ILS 31L approach at Boeing Field also has an 1800' glideslope intercept
and localizer-only minimum altitude outside the marker. The NACO plate
for that approach shows two separate 1800' indications. See
http://204.108.4.16/d-tpp/0609/00384I31L.PDF.

[Peter Clark]

On Thu, 21 Sep 2006 21:44:28 -0400, "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

It's underlined. I believe that this is read as GS intercept at 1800
(lightning bolt and start of descent on profile view), but remain at
or above 1800 until the LOM for the glideslope only.

[Mark Hansen]

On 09/22/06 11:55, Peter Clark wrote:
> On Thu, 21 Sep 2006 21:44:28 -0400, "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
>
> It's underlined. I believe that this is read as GS intercept at 1800
> (lightning bolt and start of descent on profile view), but remain at
> or above 1800 until the LOM for the glideslope only.

Somethings not right there, Peter. If you remain at or above 1800 MSL
until the LOM, you'll be above the GS. The GS crosses the LOM at 1586 MSL

Perhaps you meant "... remain at 1800 for LOC only"?

.... which is correct, by the way ;-)

--
Mark Hansen, PP-ASEL, Instrument Airplane
Cal Aggie Flying Farmers
Sacramento, CA

[Peter Clark]

On Fri, 22 Sep 2006 12:04:03 -0700, Mark Hansen
> wrote:

>On 09/22/06 11:55, Peter Clark wrote:
>> On Thu, 21 Sep 2006 21:44:28 -0400, "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
>>
>> It's underlined. I believe that this is read as GS intercept at 1800
>> (lightning bolt and start of descent on profile view), but remain at
>> or above 1800 until the LOM for the glideslope only.
>
>Somethings not right there, Peter. If you remain at or above 1800 MSL
>until the LOM, you'll be above the GS. The GS crosses the LOM at 1586 MSL
>
>Perhaps you meant "... remain at 1800 for LOC only"?

Yea, what he said ;)

[Sam Spade]

Mark Hansen wrote:
> On 09/22/06 11:55, Peter Clark wrote:
>
>>On Thu, 21 Sep 2006 21:44:28 -0400, "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
>>
>>It's underlined. I believe that this is read as GS intercept at 1800
>>(lightning bolt and start of descent on profile view), but remain at
>>or above 1800 until the LOM for the glideslope only.
>
>
> Somethings not right there, Peter. If you remain at or above 1800 MSL
> until the LOM, you'll be above the GS. The GS crosses the LOM at 1586 MSL
>
> Perhaps you meant "... remain at 1800 for LOC only"?
>
> ... which is correct, by the way ;-)
>
The note is a mistake.

[Sam Spade]

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
>
> --Gary
>
>
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.

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

[Sam Spade]

Gary Drescher wrote:
> "John R. Copeland" > wrote in message
> ...
>
>>"Gary Drescher" > wrote in message
...
>>
>>>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
>>
>>Maybe a little ambiguous, instead of a full-blown error.
>>The note applies to the "1800 ft", not to the glide-slope intercept.
>
>
> But on the NACO plate, 1800' *is* the glide slope intercept altitude (it's
> so designated by the zig-zag arrow from the "1800" to the intercept point).
>
>
>>Jeppesen clearly shows 1800 ft to the marker for the LOC approach,
>>whereas the ILS intercepts the glide path well outside the marker.
>>Without GS, you won't go below 1800 ft until reaching the marker.
>
>
> 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
>
>
That chart is wrong, too.

[Peter Clark]

On Fri, 22 Sep 2006 21:28:33 GMT, Sam Spade > wrote:

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

Where the GS intercept and the LOC FAF crossing altitude differ by 214
feet in the Nashua procedure why would the note be a mistake?

[Sam Spade]

Peter Clark wrote:
> On Fri, 22 Sep 2006 21:28:33 GMT, Sam Spade > wrote:
>
>
>>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
>>>
>>>--Gary
>>>
>>>
>>
>>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.
>>
>>The procedure will be corrected by NOTAM sometime next week (or so they
>>say. ;-)
>
>
> Where the GS intercept and the LOC FAF crossing altitude differ by 214
> feet in the Nashua procedure why would the note be a mistake?

The G/S intercept altitude and the LOC crossing altitude are both 1,800.
You are confusing G/S intercept altitude with G/S altitude at the
non-precision FAF (The P-FAF is where the G/S and 1,800 are coincident).

[Mark Hansen]

On 09/22/06 15:01, Peter Clark wrote:
> On Fri, 22 Sep 2006 21:28:33 GMT, Sam Spade > wrote:
>
>>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
>>>
>>> --Gary
>>>
>>>
>>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.
>>
>>The procedure will be corrected by NOTAM sometime next week (or so they
>>say. ;-)
>
> Where the GS intercept and the LOC FAF crossing altitude differ by 214
> feet in the Nashua procedure why would the note be a mistake?

That's not what's happening. When you're flying the ILS, you'll intercept
the GS at 1800MSL. When you're flying the localizer approach, you'll
cross the FAF at ... let's see... 1800MSL ;-)


--
Mark Hansen, PP-ASEL, Instrument Airplane
Cal Aggie Flying Farmers
Sacramento, CA

[Peter Clark]

On Fri, 22 Sep 2006 22:06:58 GMT, Sam Spade > wrote:

>Peter Clark wrote:
>> On Fri, 22 Sep 2006 21:28:33 GMT, Sam Spade > wrote:
>>
>>
>>>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
>>>>
>>>>--Gary
>>>>
>>>>
>>>
>>>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.
>>>
>>>The procedure will be corrected by NOTAM sometime next week (or so they
>>>say. ;-)
>>
>>
>> Where the GS intercept and the LOC FAF crossing altitude differ by 214
>> feet in the Nashua procedure why would the note be a mistake?
>
>The G/S intercept altitude and the LOC crossing altitude are both 1,800.
> You are confusing G/S intercept altitude with G/S altitude at the
>non-precision FAF (The P-FAF is where the G/S and 1,800 are coincident).

OK, I admit I must be missing something here. The way I read your
message above WRT this procedure, if you're on the ILS fly the PT (or
vectors) and descend to 1800 and subsequently intercept and descend on
the glideslope. If you're flying the LOC only procedure you have to
fly to the LOM before descending, maintaining 1800' because you don't
have any other way to identify the point where you start the descent.
If you were on the glideslope at this point you would be at 1586 feet,
thus the note for maintaining 1800' LOC only past the GS intercept.
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?

[Peter Clark]

On Fri, 22 Sep 2006 15:10:11 -0700, Mark Hansen
> wrote:

>On 09/22/06 15:01, Peter Clark wrote:
>> On Fri, 22 Sep 2006 21:28:33 GMT, Sam Spade > wrote:
>>
>>>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
>>>>
>>>> --Gary
>>>>
>>>>
>>>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.
>>>
>>>The procedure will be corrected by NOTAM sometime next week (or so they
>>>say. ;-)
>>
>> Where the GS intercept and the LOC FAF crossing altitude differ by 214
>> feet in the Nashua procedure why would the note be a mistake?
>
>That's not what's happening. When you're flying the ILS, you'll intercept
>the GS at 1800MSL. When you're flying the localizer approach, you'll
>cross the FAF at ... let's see... 1800MSL ;-)

Oh, OK. So basically the 1800' intercepting the glideslope is
extrapolated over to the LOM because without the glideslope you have
no other altitude to hold until that point. The note made sense to me
when looking at in relation to the plan view, but I use Jepp charts so
didn't look too carefully at the NOS version.

[Mark Hansen]

On 09/22/06 15:34, Peter Clark wrote:
> On Fri, 22 Sep 2006 15:10:11 -0700, Mark Hansen
> > wrote:
>
>>On 09/22/06 15:01, Peter Clark wrote:
>>> On Fri, 22 Sep 2006 21:28:33 GMT, Sam Spade > wrote:
>>>
>>>>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
>>>>>
>>>>> --Gary
>>>>>
>>>>>
>>>>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.
>>>>
>>>>The procedure will be corrected by NOTAM sometime next week (or so they
>>>>say. ;-)
>>>
>>> Where the GS intercept and the LOC FAF crossing altitude differ by 214
>>> feet in the Nashua procedure why would the note be a mistake?
>>
>>That's not what's happening. When you're flying the ILS, you'll intercept
>>the GS at 1800MSL. When you're flying the localizer approach, you'll
>>cross the FAF at ... let's see... 1800MSL ;-)
>
> Oh, OK. So basically the 1800' intercepting the glideslope is
> extrapolated over to the LOM because without the glideslope you have
> no other altitude to hold until that point.

Well, you lost me there ;-(

This IAP requires:

When flying the LOC approach, you maintain 1800MSL until you cross the
FAF, which is located at the LOM.

When flying the ILS, you should intercept the glide slope from 1800MSL.

When these two altitudes are different by more than 20 feet, the note
is required (according to the information provided by Sam. It is because
these altitudes are not difference (by more than 20 feet) that the note
is a mistake.

The 1586 on the chart is simply the altitude you should be at when on
the glide slope and crossing the LOM. If you're flying the LOC-only
approach, the 1586 is not of any value (that I'm aware of) as you'll
be crossing the LOM at 1800MSL, then beginning your descent.

I don't know if this is causing any confusion, but just to clarify:

You must fly the PT at or above 3400. However, once you've turned
inbound and have captured the localizer beam (more or less), you
can descend to 1800. This is why you may want to fly your outbound
leg a little longer than one minute.


> The note made sense to me
> when looking at in relation to the plan view, but I use Jepp charts so
> didn't look too carefully at the NOS version.



--
Mark Hansen, PP-ASEL, Instrument Airplane
Cal Aggie Flying Farmers
Sacramento, CA

[Sam Spade]

Peter Clark wrote:
> On Fri, 22 Sep 2006 22:06:58 GMT, Sam Spade > wrote:
>
>
>>Peter Clark wrote:
>>
>>>On Fri, 22 Sep 2006 21:28:33 GMT, Sam Spade > wrote:
>>>
>>>
>>>
>>>>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
>>>>>
>>>>>--Gary
>>>>>
>>>>>
>>>>
>>>>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.
>>>>
>>>>The procedure will be corrected by NOTAM sometime next week (or so they
>>>>say. ;-)
>>>
>>>
>>>Where the GS intercept and the LOC FAF crossing altitude differ by 214
>>>feet in the Nashua procedure why would the note be a mistake?
>>
>>The G/S intercept altitude and the LOC crossing altitude are both 1,800.
>> You are confusing G/S intercept altitude with G/S altitude at the
>>non-precision FAF (The P-FAF is where the G/S and 1,800 are coincident).
>
>
> OK, I admit I must be missing something here. The way I read your
> message above WRT this procedure, if you're on the ILS fly the PT (or
> vectors) and descend to 1800 and subsequently intercept and descend on
> the glideslope. If you're flying the LOC only procedure you have to
> fly to the LOM before descending, maintaining 1800' because you don't
> have any other way to identify the point where you start the descent.
> If you were on the glideslope at this point you would be at 1586 feet,
> thus the note for maintaining 1800' LOC only past the GS intercept.
> 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.

[Peter Clark]

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.

[JPH]

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

[Gary Drescher]

"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

[Gary Drescher]

"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

[Sam Spade]

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?

[Sam Spade]

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.

[Gary Drescher]

"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

[Gary Drescher]

"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

[Sam Spade]

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?

[Sam Spade]

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.

[Gary Drescher]

"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

[Sam Spade]

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. ;-)

[JPH]

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