why is intercept altitude labeled "LOC only"?

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.

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. ;-)

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.

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?

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).

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

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?

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.

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

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.