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)