Jepp vs NOS at PRB

In article ,
Ron Rosenfeld wrote:

According to my interpretation of the Jepp chart, DIYAD is formed by the
intersection of the HUO 094R and the LOC; or by the 13.5DME point on the
HUO 094R

Yes. I get the same from reading the NOS chart, so at least we're both
on the same page.

But, what I don't understand is what value it is knowing that DIYAD is
13.5 DME from HUO. The only real reason DIYAD exists is to specify a
fixed distance out on the localizer course, and HUO DME doesn't help you
do that.

According to my interpretation of the Jepp chart, DIYAD is formed by the
intersection of the HUO 094R and the LOC; or by the 13.5DME point on the
HUO 094R


Yes, that is true. And the DME distance might be useful to someone coming in
from HUO. However, the DME (and not the radial) is charted in the plan view.
If they are going to go through the trouble (and clutter) of putting the DME
there, I'd rather see the radial. Especially since the same VOR (different
radial) is used to identify NISSN.

Jose

--
(for Email, make the obvious changes in my address)

On Wed, 5 May 2004 18:15:44 -0500, "Stan Prevost"
wrote:


"Ron Rosenfeld" wrote in message
.. .
On Wed, 5 May 2004 16:55:57 -0500, "Stan Prevost"
wrote:

I'm wondering if the NACO chart shows the barb at EXUPY as a
*recommended*
PT commencement point, because one can initiate a nice three degree
stabilized descent from there.

According to what others have written in the past, it is there only for
charting convenience. In other words, whoever designed the chart thought
things would look less cluttered that way.


Yes, it could have been purely for that reason. However, it seems that the
PT barb could have easily been shown inside 10 DME without clutter. And it
is interesting that EXUPY is the point at which a three degree descent would
begin to the VOR, and that invites speculation as to coincidence or intent.
One could do worse than choosing EXUPY as a point for initiating the PT.
Coming in from IAF KIKII, one would begin descent from 3600 at EXUPY, and a
stabilized 3 degree descent could be made all the way to the airport from
there, and it seems possible that the charting person chose to show the PT
barb outside EXUPY, on the 3600 ft segment, as a suggestion to the pilot as
to where to execute the PT. Since s/he has the discretion.....

Stan



I don't use NACO charts so that's why I ask these questions:

Do you have any documentation to indicate that the location of barb
placement on a NACO chart is determined by this method?

Is it a standard for NACO charts that the barb is placed at the 3° descent
point?


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

Ron Rosenfeld wrote:

On Wed, 05 May 2004 10:09:36 -0700, wrote:



Ron Rosenfeld wrote:

Where in the AIM? I don't think this issue would be clarified without the
use of common sense (i.e., reading the entire chart in context...profile
and plan views) or a good reading of both the NACO and Jeppesen approach
chart legends.

5-4-8 a.1. ... However, the point at which the turn may be commenced and
the type and rate of turn is left to the discretion of the pilot.

I fail to see where that AIM language helps me read the chart if I am otherwise
of limited clues. ;-)

Ron Rosenfeld wrote:

Well, if a person is unwilling to read and learn, then nothing will
change his mind.

Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

Well stated. Nonetheless, use of both the plan and profile views of an IAP
is probably best enhanced by some ground school in the chart legends for
both NACO and Jepp.

Alas, some feds assume all this stuff is self-evident. And, the PRB is a
great example of where you really do need to understand what the chart is
conveying.

Ron Rosenfeld wrote:

On Wed, 5 May 2004 16:55:57 -0500, "Stan Prevost"
wrote:

I'm wondering if the NACO chart shows the barb at EXUPY as a *recommended*
PT commencement point, because one can initiate a nice three degree
stabilized descent from there.

According to what others have written in the past, it is there only for
charting convenience. In other words, whoever designed the chart thought
things would look less cluttered that way.


The barb is charting convention. The procedure turn limited and side of course
is regulatory.

Roy Smith wrote:

wrote:
Charting convention places the burden for clarity of the course
reversal in the profile view.

Frank,

I'm not saying you're wrong (in fact, what you say makes a lot of
sense), but is there some reference you could give to that? It's not
anything I've ever seen in any of the standard reference materials.

The NACO chart legend implies it, but I suspect it is only spelled out in
the IACC specs. (Inter-agency Cartographic Commission, or something like
that, specifications.) Often, the feds miss spelling out this stuff to the
users, because it makes sense to all of them sitting around a table for
their closed meetings.~



On that note, I remember once flying the MGJ ILS-3 for practice
(http://www.myairplane.com/databases/...fs/05264I3.pdf). Shame
on me, I hadn't really briefed the approach, and just winged it. I flew
the procedure turn a minute outside of the LOM and ended up AFU.

It's kind of tricky. The first trick is that the PT doesn't start at
the LOM, but at DIYAD. The second trick is that there's a stepdown at
NISSN inbound from the PT, so you really need to be outside of NISSN
before you start the PT, not just outside of DIYAD. The third trick is
that DIYAD and NISSN are both defined by DME, but from different sources
(neither of which is the ILS).

There's a note on the profile view saying "Remain within 10 NM", but I'm
not 100% sure from *where*. I'm reasonably sure it means 10 NM from
DIYAD, but given NISSN, I'm not quite certain about that.

The descending thick black line begins at DIYAD, so that is the fix upon
which the PT is predicated. If you feel this is inadequately explained, a
well crafted letter to the NACO charting folks in Silver Springs, MD would
be helpful. In my many years of flying it seemed obvious to me, but gee, I
can't cite a public reference.



Lastly, it beats the hell out of me why anybody would care that DIYAD is
13.5 DME from HUO. Given the crossing angles, I could see that being on
the localizer and 20.8 DME from SAX is a good way to identify NISSN, but
being on the localizer and being 13.5 DME from HUO is pretty worthless
as a way to identify DIYAD. GPS is wonderful :-)

The 13.5 DME is there for arrival from HUO to the LOC. The fact it's
charted in the profile view is a mistake in the manner in which the data
were entered into the system. Keep in mind, you're dealing with the same
FAA here who has all but thrown the towel in on WAAS on one hand, yet on the
other hand is going to make it work, "damn it!" ...and so forth.



This is a great approach for training purposes. It's a confusing mess
for flying for real. But it does serve to show a student why briefing
an approach before you actually get to the IAF is a good idea :-)

"Ron Rosenfeld" wrote in message
...
On Wed, 5 May 2004 18:15:44 -0500, "Stan Prevost"
wrote:


I don't use NACO charts so that's why I ask these questions:

Do you have any documentation to indicate that the location of barb
placement on a NACO chart is determined by this method?

Is it a standard for NACO charts that the barb is placed at the 3° descent
point?



I didn't mean to imply that either is standard procedure, and I'm quite sure
neither is. I was just speculating that, given the combination of factors
in this approach, the particular chart designer may have acted within the
scope of his charting discretion to chart the PT barb at a logical point,
even though the exact placement has no regulatory meaning.

Stan

Well, if a person is unwilling to read and learn, then nothing will
change his mind.

I think that's a bit unfair. Whether a person was taught correctly or
incorrectly is a matter of chance; when someone later seeks to change
his mind, what authoritative evidence is available?

Many people want to learn, but they aren't sure whom to trust. In the
end, most are persuaded by the highest status individual with a firm
opinion.

On Wed, 5 May 2004 22:18:13 -0500, "Stan Prevost"
wrote:

I didn't mean to imply that either is standard procedure, and I'm quite sure
neither is. I was just speculating that, given the combination of factors
in this approach, the particular chart designer may have acted within the
scope of his charting discretion to chart the PT barb at a logical point,
even though the exact placement has no regulatory meaning.

Stan

Fair enough.

In that case, my interpretation would be that it is there only by chance.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)