GPS approach question

A few weeks ago I flew a practice GPS RWY 24 approach into ELM. I don't
recall the exact heading coming in, but it was in the sector leading to
CIMAN. I'm new to GPS approaches having just returned after several
years of inactivity, and still haven't got all the nuances figured out.
I expected from what I've read about GPS approaches to be cleared to
CIMAN to commence the approach, then sequence to MAPOE, CERUP, etc. with
no PT. Instead, the controller cleared me to MAPOE. At that point I
wasn't sure exactly what was expected, but I was flying with an
instructor and he said I'd need to fly the PT in this case. I thought
when you came in a certain TAA that you'd fly to the fix for that area
and then fly the approach. However, in the case of this approach, this
would preclude use of the PT for all cases as CIMAN and BUTRE are both
noPT and the TAA leading directly to MAPOE is also marked noPT. So,
that would seem to make the PT unnecessary other than in the case I was
given which is a direct approach to MAPOE from other than the TAA
indicated for MAPOE.

Is this a common occurrence when flying GPS approaches? Is this the
only scenario where the PT is applicable in this case?


Matt

Matt Whiting wrote:
A few weeks ago I flew a practice GPS RWY 24 approach into ELM. I don't
recall the exact heading coming in, but it was in the sector leading to
CIMAN. I'm new to GPS approaches having just returned after several
years of inactivity, and still haven't got all the nuances figured out.

Welcome to the club. When you figure out all the nuances, let me know;
every time I think I finally understand it all, some controller throws a
new nuance at me :-)

I expected from what I've read about GPS approaches to be cleared to
CIMAN to commence the approach, then sequence to MAPOE, CERUP, etc. with
no PT. Instead, the controller cleared me to MAPOE. At that point I
wasn't sure exactly what was expected, but I was flying with an
instructor and he said I'd need to fly the PT in this case.

I agree with your instructor, and I agree with you too (with a position
like that, I should be running for president, eh?)

Here's how I understand it. If you were approaching from the west, the
normal thing would have been to issue you "direct CIMAN, maintain 4000
until established, cleared GPS-24 approach" In that case, you would
indeed have flown CIMAN, MAPOE, CERUP, etc, with no PT. But, the
controller didn't clear you to CIMAN, he cleared you to MAPOE. It's not
the way the approach was intended to be flown, but it's not illegal.
Since you were not approaching MAPOE from within the 153-333 arc, you
had to fly a PT (in this case, a 4NM racetrack, as charted).

The obvious question is, "Why did the controller do that?". I don't
know, but I can make a couple of guesses. One guess is that he doesn't
really get GPS approaches yet, and just plain did the sub-optimal thing.
One can imagine the conversation in the radar room: "Hey Bob, if I
clear this guy direct MAPOE, is he going to do a PT?", "Beats me, why
don't you try it and whatch what he does". The other guess is that he
had some operational need to delay your arrival and forcing you to do
the PT was the simpliest way to achive that.

Matt,
I'm still fairly new at the whole Instrument flying stuff.
But I have yet to come across a Procedure Turn on any GPS approach.
I was under the impression that most were designed so that you could
basically make a straight, left base or right base entry with no PT allowed
or required.

But as my ex-wife might say " I may be wrong".

David (KORL)

"Matt Whiting" wrote in message...

A few weeks ago I flew a practice GPS RWY 24 approach into ELM. I don't
recall the exact heading coming in, but it was in the sector leading to
CIMAN. I'm new to GPS approaches having just returned after several years
of inactivity, and still haven't got all the nuances figured out. I
expected from what I've read about GPS approaches to be cleared to CIMAN
to commence the approach, then sequence to MAPOE, CERUP, etc. with no PT.
Instead, the controller cleared me to MAPOE. At that point I wasn't sure
exactly what was expected, but I was flying with an instructor and he said
I'd need to fly the PT in this case. I thought when you came in a certain
TAA that you'd fly to the fix for that area and then fly the approach.
However, in the case of this approach, this would preclude use of the PT
for all cases as CIMAN and BUTRE are both noPT and the TAA leading
directly to MAPOE is also marked noPT. So, that would seem to make the PT
unnecessary other than in the case I was given which is a direct approach
to MAPOE from other than the TAA indicated for MAPOE.

Is this a common occurrence when flying GPS approaches? Is this the only
scenario where the PT is applicable in this case?


Matt

http://204.108.4.16/d-tpp/0411/05648R12.PDF

(recently much discussed airport)

"CFLav8r" wrote in message
.. .
Matt,
I'm still fairly new at the whole Instrument flying stuff.
But I have yet to come across a Procedure Turn on any GPS approach.
I was under the impression that most were designed so that you could
basically make a straight, left base or right base entry with no PT
allowed
or required.

But as my ex-wife might say " I may be wrong".

David (KORL)

"Matt Whiting" wrote in message...

A few weeks ago I flew a practice GPS RWY 24 approach into ELM. I don't
recall the exact heading coming in, but it was in the sector leading to
CIMAN. I'm new to GPS approaches having just returned after several
years of inactivity, and still haven't got all the nuances figured out. I
expected from what I've read about GPS approaches to be cleared to CIMAN
to commence the approach, then sequence to MAPOE, CERUP, etc. with no PT.
Instead, the controller cleared me to MAPOE. At that point I wasn't sure
exactly what was expected, but I was flying with an instructor and he
said I'd need to fly the PT in this case. I thought when you came in a
certain TAA that you'd fly to the fix for that area and then fly the
approach. However, in the case of this approach, this would preclude use
of the PT for all cases as CIMAN and BUTRE are both noPT and the TAA
leading directly to MAPOE is also marked noPT. So, that would seem to
make the PT unnecessary other than in the case I was given which is a
direct approach to MAPOE from other than the TAA indicated for MAPOE.

Is this a common occurrence when flying GPS approaches? Is this the only
scenario where the PT is applicable in this case?


Matt

On Sun, 31 Oct 2004 20:11:47 -0500, Matt Whiting
wrote:



Is this a common occurrence when flying GPS approaches? Is this the
only scenario where the PT is applicable in this case?


I don't know whether it is common or not, but there does not seem to be
anything wrong with the clearance (or your instructor's interpretation of
the need for a PT).

You might also have to execute a PT at MAPOE if you were too high when you
got there, even if you were coming from the straight-in area.

In general, in flying approaches, if I desire a specific approach that is
not the one being used, I will request it. With regard to GPS approaches,
if I desire a particular IAF, I will specifically request it, too. So far,
I've not been refused (or had to hold because of the request).

As to why ATC cleared via MAPOE instead of CIMAN, ATC may have felt that
would be a shorter route. I do not believe that ATC thinks that executing
a PT is any big deal for a pilot, so they would most likely clear you for
an approach via the closest IAF to your location. OR he may have wanted
you to go that way for traffic reasons.

There's no rule of which I am aware that says that if you are in the left
base area, that you need to be cleared via the associated IAF.




--ron

Matt Whiting ) wrote:

Instead, the controller cleared me to MAPOE.

While practicing GPS approaches across NY state, I have found that
controllers will often clear me to the IAF aligned with the final
approach course of the approach. I am guessing that years of handing
out ILS approaches have made them accustomed to this.

When this happens, I request the IAF closest to my position that
prevents me from having to do a PT. I have yet to be denied this
request.

In your case, you could have responded to the controller's clearance
with a request the CIMAN IAF. Of course, this is a moot point if you
really needed to practice a PT, but had you been by yourself in the
soup, why not make the approach as easy as possible?


--
Peter

"Ron Rosenfeld" wrote in message
...
....snip...
As to why ATC cleared via MAPOE instead of CIMAN, ATC may have felt that
would be a shorter route. ...snip...

There's no rule of which I am aware that says that if you are in the left
base area, that you need to be cleared via the associated IAF.



If the track from present-position to MAPOE is fairly close to 063... even
if technically in that IAF=CIMAN quadrant... would not the controller (and
the pilot) think it more convenient to go direct MAPOE and make the turn,
rather than having to swing out 5 miles to CIMAN and come back???

On Mon, 1 Nov 2004 10:13:58 -0500, "Icebound"
wrote:

If the track from present-position to MAPOE is fairly close to 063... even
if technically in that IAF=CIMAN quadrant... would not the controller (and
the pilot) think it more convenient to go direct MAPOE and make the turn,
rather than having to swing out 5 miles to CIMAN and come back???

That was the point I was trying to make. Except I would be looking at the
distance rather than the track.
--ron

Icebound wrote:
If the track from present-position to MAPOE is fairly close to 063... even
if technically in that IAF=CIMAN quadrant... would not the controller (and
the pilot) think it more convenient to go direct MAPOE and make the turn,
rather than having to swing out 5 miles to CIMAN and come back???

A procedure turn takes about 4 minutes to exectute (yes, I know there
are things other than the 45-225 turn that could be done faster).
Even a 172/Warrior class plane can cover 5-6 miles in that time, so as
long as you don't wait until the last minute and have to make some
extreme course change to head for the outer IAF, it's probably about a
wash either way. The faster the aircraft, the more the T-IAF comes
out ahead.

And, given that it's about a wash, I'd rather make two 90 degree turns
with a 5-mile straight leg and positive course guidance between them
than dead-reckon my way through a procedure turn.