Jepp vs NOS at PRB

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.

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.

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 :-)

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 :-)

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.

That just begs the question. If the person is under the impression
that the PT can't begin until some irrelevant fix in the planview,
then all the AIM tells him is that once he reaches that fix, THEN he
can begin the PT whenver and however he wants.

A person who has a misconception is likely to interpret anything he
sees or hears in light of his misconception. Unless there is
*specific*, authoritative information to root out the initial error,
getting him to change his mind will be difficult.

The only reason that the error of this present belief was instantly
obvious to me was that I had read a number of articles (Wally Roberts)
and publications (TERPS, etc) describing how the PT protected areas
are constructed.

wrote in message ...


Doug Campbell wrote:

I was training with Jepp charts, and my partner (safety pilot) had NOS,
and
we
were attempting the VOR DME (GPS) B approach into Paso Robles. The Jepp
chart shows the procedure turn (when starting at the VOR, not the arc)

You guys need some chart instruction. Look at the profile view of the NOS
chart. The descending thick black line marked 133 degrees starts at
ILSIC.
(PRB 133/3 DME). That is the procedure turn fix, without ambiguity.



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.

Stan

The third trick is
that DIYAD and NISSN are both defined
by DME, but from different sources
(neither of which is the ILS).


Consider the position of HUO (which is the source of the DME for DIYAD). It
makes no sense to me. The DME distance will not be changing much as you travel
a long way along the FAC. Like you, I don't understand why they didn't use
SAX for both.

Jose


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

On Wed, 05 May 2004 20:45:04 GMT, Greg Esres wrote:

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.

That just begs the question. If the person is under the impression
that the PT can't begin until some irrelevant fix in the planview,
then all the AIM tells him is that once he reaches that fix, THEN he
can begin the PT whenver and however he wants.

A person who has a misconception is likely to interpret anything he
sees or hears in light of his misconception. Unless there is
*specific*, authoritative information to root out the initial error,
getting him to change his mind will be difficult.

The only reason that the error of this present belief was instantly
obvious to me was that I had read a number of articles (Wally Roberts)
and publications (TERPS, etc) describing how the PT protected areas
are constructed.

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)

On Wed, 05 May 2004 16:28:44 -0400, Roy Smith wrote:

Roy,


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.

That's interesting. Fortunately I have my Jepp charts which show them in
different places. But on the NACO chart you reference, to me they look
like they're in the same spot :-).

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.

I disagree. You only need to become established inbound far enough from
DIYAD so that you can descend from 3000' to 1800' at a comfortable rate of
descent. The presence of the stepdown only tells you what altitude to
maintain if you are outside of that stepdown fix. It does NOT tell you you
can't start the PT at DIYAD or finish it inside of NISSN.


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.


It's 10 NM from DIYAD. (And it is stated so explicitly on the Jepp chart).


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 :-)

Diyad is also on the LOC.



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

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.


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

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 :-)

Diyad is also on the LOC.


Yes, it is. And the best information from the localizer is "left or right of
course", which translates roughly into "too far East, too far West". To
augment this and get an actual location, you need something whose best
information is "too far North, too far South. DME from SAX does this (since
SAX is roughly South). DME from the LOC (if it's available) is even better.
However, DME from HUO (which is to the West) is going to tell you "too far
West, too far East".

But you already know this from the localizer.

Jose

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

On 05 May 2004 22:34:39 GMT, (Teacherjh) wrote:


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 :-)

Diyad is also on the LOC.


Yes, it is. And the best information from the localizer is "left or right of
course", which translates roughly into "too far East, too far West". To
augment this and get an actual location, you need something whose best
information is "too far North, too far South. DME from SAX does this (since
SAX is roughly South). DME from the LOC (if it's available) is even better.
However, DME from HUO (which is to the West) is going to tell you "too far
West, too far East".

But you already know this from the localizer.

Jose

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


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

"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