Change in AIM wording concerning procedure turn

"Brad Salai" wrote in message
...

"Gary Drescher" wrote in message
...

No, the ambiguity I'm pointing out isn't just a matter of the vagueness
of
"course reversal". The new AIM phrasing is ambiguous as to whether the
enumerated conditions are meant only as an *elaboration* of what it means
for a course reversal to be unnecessary (in which case a charted PT is
required unless the enumerated conditions are met), or whether a lack of
need for a course-reversal is meant as an *addition* to the enumerated
conditions (in which case the PT might not be required even if none of
the
enumerated conditions are met).

I think its the second case. Here is the language again:

The procedure turn or hold in lieu of procedure turn is a required
maneuver when it is necessary to perform a course reversal.
The procedure turn is not required when the symbol "No PT" is shown,
when
RADAR VECTORING to the final approach course is provided, when
conducting a timed approach, or when the procedure turn is not
authorized.

The first sentence doesn't make any sense unless there are situations
where
"it is necessary to perform a course reversal."

Sure.

If that's true, then the
second sentence must be exceptions to the first, that is, situations where
it would appear "necessary to perform a course reversal" but a PT is not
required.

Yes and no. Yes, the second sentence lists situations in which a charted PT
is not required (the PT does not necessarily "appear necessary" in those
situations, though, except to the extent that simply being charted might
make them appear necessary). But no, the second sentence doesn't list
exceptions to the if-then assertion made by the first sentence; that is, the
second sentence does not list situations in which there is a necessary
course reversal but not a required PT.

If the intent were that a PT is required unless one of the four exceptions
applied, they would (or at least should) have said:

The procedure turn or hold in lieu of procedure turn is a required
maneuver unless the symbol "No PT" is shown, when
RADAR VECTORING to the final approach course is provided, when
conducting a timed approach, or when the procedure turn is not
authorized.
which would have been clear and unambiguous.

Yes, if that was their intent, they should have used that wording, or else
they should have used the "elaboration" paraphrase I proposed earlier in the
thread. But if their intent was as you believe, then they should have used
the "addition" paraphrase I proposed, which would also have been clear and
unambiguous. In fact, though, they used neither, and their chosen phrasing
was not clear or unambiguous.

General rules of construction
suggest that you should interpret the language so that the first sentence
is
not redundant or meaningless,

Correct.

which leads to the second interpretation, what G. Drescher calls
*addition*.

No, because my "elaboration" interpretation *also* allows the first sentence
to be meaningful and not redundant. Here is the "elaboration" paraphrase
again:

"The procedure turn is a required maneuver, unless one of the following
conditions obtains, in which case a course reversal is unnecessary: 1) the
symbol 'NoPT' is shown; 2) radar vectoring to the final approach course is
provided; 3) you are conducting a timed approach; or 4) the procedure turn
is not authorized."

In this paraphrase, the sentence in question is construed to be explaining
the rationale for the exceptions--namely, that the reason the PT maneuver
isn't required in the exceptional cases is that a reversal of course is
deemed unnecessary in those cases. That explanation may not be profound, but
it is neither meaningless nor redundant.

So the AIM wording is ambiguous. But if we look beyond the wording to the
underlying logic, then the "elaboration" interpretation makes more sense
than the "addition" interpretation that you favor. That's because the
"addition" interpretation effectively expects the pilot to act as a
real-time approach designer, making her own decision as to the necessity for
a course reversal (presumably in compliance with the TERPS criteria, which
are not even part of the standard pilot curriculum). In contrast, the
"elaboration" interpretation expects the TERPS criteria to be used by the
approach-chart designer, and simply expects the pilot to comply with the
chart.

The FAA email that Tim posted earlier in the thread confirms that the FAA's
intent is indeed the "elaboration" interpretation (but of course that's not
authoritative until it appears in some official source).

--Gary

"Gary Drescher" wrote in message
...
"Brad Salai" wrote in message
...

"Gary Drescher" wrote in message
...

No, the ambiguity I'm pointing out isn't just a matter of the vagueness
of
"course reversal". The new AIM phrasing is ambiguous as to whether the
enumerated conditions are meant only as an *elaboration* of what it
means
for a course reversal to be unnecessary (in which case a charted PT is
required unless the enumerated conditions are met), or whether a lack
of
need for a course-reversal is meant as an *addition* to the enumerated
conditions (in which case the PT might not be required even if none of
the
enumerated conditions are met).

I think its the second case. Here is the language again:

The procedure turn or hold in lieu of procedure turn is a required
maneuver when it is necessary to perform a course reversal.
The procedure turn is not required when the symbol "No PT" is shown,
when
RADAR VECTORING to the final approach course is provided, when
conducting a timed approach, or when the procedure turn is not
authorized.

The first sentence doesn't make any sense unless there are situations
where
"it is necessary to perform a course reversal."

Sure.

If that's true, then the
second sentence must be exceptions to the first, that is, situations
where
it would appear "necessary to perform a course reversal" but a PT is not
required.

Yes and no. Yes, the second sentence lists situations in which a charted
PT
is not required (the PT does not necessarily "appear necessary" in those
situations, though, except to the extent that simply being charted might
make them appear necessary). But no, the second sentence doesn't list
exceptions to the if-then assertion made by the first sentence; that is,
the
second sentence does not list situations in which there is a necessary
course reversal but not a required PT.

If the intent were that a PT is required unless one of the four
exceptions
applied, they would (or at least should) have said:

The procedure turn or hold in lieu of procedure turn is a required
maneuver unless the symbol "No PT" is shown, when
RADAR VECTORING to the final approach course is provided, when
conducting a timed approach, or when the procedure turn is not
authorized.
which would have been clear and unambiguous.

Yes, if that was their intent, they should have used that wording, or else
they should have used the "elaboration" paraphrase I proposed earlier in
the
thread. But if their intent was as you believe, then they should have used
the "addition" paraphrase I proposed, which would also have been clear and
unambiguous. In fact, though, they used neither, and their chosen phrasing
was not clear or unambiguous.

General rules of construction
suggest that you should interpret the language so that the first
sentence
is
not redundant or meaningless,

Correct.

which leads to the second interpretation, what G. Drescher calls
*addition*.

No, because my "elaboration" interpretation *also* allows the first
sentence
to be meaningful and not redundant. Here is the "elaboration" paraphrase
again:

"The procedure turn is a required maneuver, unless one of the following
conditions obtains, in which case a course reversal is unnecessary: 1) the
symbol 'NoPT' is shown; 2) radar vectoring to the final approach course is
provided; 3) you are conducting a timed approach; or 4) the procedure turn
is not authorized."

In this paraphrase, the sentence in question is construed to be explaining
the rationale for the exceptions--namely, that the reason the PT maneuver
isn't required in the exceptional cases is that a reversal of course is
deemed unnecessary in those cases. That explanation may not be profound,
but
it is neither meaningless nor redundant.

So the AIM wording is ambiguous. But if we look beyond the wording to the
underlying logic, then the "elaboration" interpretation makes more sense
than the "addition" interpretation that you favor. That's because the
"addition" interpretation effectively expects the pilot to act as a
real-time approach designer, making her own decision as to the necessity
for
a course reversal (presumably in compliance with the TERPS criteria, which
are not even part of the standard pilot curriculum). In contrast, the
"elaboration" interpretation expects the TERPS criteria to be used by the
approach-chart designer, and simply expects the pilot to comply with the
chart.

The FAA email that Tim posted earlier in the thread confirms that the
FAA's
intent is indeed the "elaboration" interpretation (but of course that's
not
authoritative until it appears in some official source).

--Gary

I've either persuaded myself, or been persuaded that the "elaboration"
construction is the safest, and the email suggests that it is what was
intended, but it really doesn't follow from the original language. Your
paraphrase leaves out "when it is necessary to perform a course reversal"
from the first sentence where it actually appears, and puts in in the
second, where it actually says that a PT is not necessary so that it reads
"where a course reversal is not necessary" which it didn't say.
If they had had you available to help them out when they drafted this, it
would have saved us all a lot of time.
No matter what it says, as I said before, I'm going to fly by the
elaboration construction, but no way do I agree that the words say that.

I'm still confused. Assuming the following facts, how would you fly
the ILS RWY 28R at KSFO
(http://www.naco.faa.gov/d-tpp/0510/00375I28R.PDF), which has a holding
pattern depicted in lieu of PT, and no indication that radar is
required?

Assumptions:
1) Upon departure, you were cleared to SFO, as filed;
2) your filed route takes you through the MENLO IAF (I don't know if
there's an airway through MENLO, but assume you got there for the sake
of argument);
3) you lost radio contact before your arrival at MENLO; and
4) you arrive at MENLO at 4000 feet and at your filed ETA.

Here's how I'd fly the procedure - will I be in violation of any FARs,
even given the interpretation of the AIM change that is proposed here?
1) Cross MENLO at 4000, descend to 3200 and continue to CEPIN;
2) As I approach CEPIN and as the localizer comes alive and starts
moving toward center, begin turning left to intercept localizer - note
that I will initially have almost a 50 degree intercept - and begin
descent to 1800 feet; and
3) at AXMUL, intercept glideslope and continue descent.

Why would I turn right at CEPIN or even at MENLO to spend some time in
the hold at DUMBA, except perhaps if I arrived prior to my filed ETA?

My layman's interpretation of the language would be as follows:

1) "A procedure turn is the maneuver prescribed *when it is necessary
to
perform a course reversal*..."

2) [When it is necessary to perform a course reversal,] "The procedure
turn or hold in lieu of procedure turn is a required maneuver."

3) [Even when it is necessary to perform a course reversal,] "The
procedure turn is not required when the symbol "No PT" is shown, when
RADAR VECTORING to the final approach course is provided, when
conducting a timed approach, or when the procedure turn is not
authorized."

This begs the question, "when is it necessary to perform a course
reversal?" Someone mentioned a descent of 300 feet or a turn of more
than 30 degrees according to TERPS (not according to anything we
studied to get our IFR ticket, as far as I recall), though that doesn't
seem right to me. I think even a 90 degree intercept or 1000 feet (or
more) of descent may be okay if you're far enough from the FAF.

On 1 Oct 2005 18:13:06 -0700, "rps" wrote:

I'm still confused. Assuming the following facts, how would you fly
the ILS RWY 28R at KSFO
(http://www.naco.faa.gov/d-tpp/0510/00375I28R.PDF), which has a holding
pattern depicted in lieu of PT, and no indication that radar is
required?

Assumptions:
1) Upon departure, you were cleared to SFO, as filed;
2) your filed route takes you through the MENLO IAF (I don't know if
there's an airway through MENLO, but assume you got there for the sake
of argument);
3) you lost radio contact before your arrival at MENLO; and
4) you arrive at MENLO at 4000 feet and at your filed ETA.

Here's how I'd fly the procedure - will I be in violation of any FARs,
even given the interpretation of the AIM change that is proposed here?
1) Cross MENLO at 4000, descend to 3200 and continue to CEPIN;
2) As I approach CEPIN and as the localizer comes alive and starts
moving toward center, begin turning left to intercept localizer - note
that I will initially have almost a 50 degree intercept - and begin
descent to 1800 feet; and
3) at AXMUL, intercept glideslope and continue descent.

Why would I turn right at CEPIN or even at MENLO to spend some time in
the hold at DUMBA, except perhaps if I arrived prior to my filed ETA?

I'm not as familiar with NACO charts as with Jepp charts (and I don't have
a Jepp chart for that approach) but I would not even consider turning right
at CEPIN or MENLO to go to DUMBA. It seems to me that the procedure track
from the MENLO IAF does not proceed via DUMBA. This seems apparent from
the charting; but also note that the MEA for the route from MENLO to CEPIN
is lower than the MEA in the hold at DUMBA.

So far as doing a hold if you arrived ahead of your ETA, in accord with the
regulations regarding radio failure, I believe you should be holding at
MENLO. Although, the situation may well be considered an emergency,
depending on what you are flying, and I might choose to skip this provision
of the regulations for safety reasons.


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

"rps" wrote in message
oups.com...

I'm still confused. Assuming the following facts, how would you fly
the ILS RWY 28R at KSFO
(http://www.naco.faa.gov/d-tpp/0510/00375I28R.PDF), which has a holding
pattern depicted in lieu of PT, and no indication that radar is
required?

Assumptions:
1) Upon departure, you were cleared to SFO, as filed;
2) your filed route takes you through the MENLO IAF (I don't know if
there's an airway through MENLO, but assume you got there for the sake
of argument);


MENLO is on the BIG SUR TWO arrival.



3) you lost radio contact before your arrival at MENLO; and
4) you arrive at MENLO at 4000 feet and at your filed ETA.

Here's how I'd fly the procedure - will I be in violation of any FARs,
even given the interpretation of the AIM change that is proposed here?
1) Cross MENLO at 4000, descend to 3200 and continue to CEPIN;
2) As I approach CEPIN and as the localizer comes alive and starts
moving toward center, begin turning left to intercept localizer - note
that I will initially have almost a 50 degree intercept - and begin
descent to 1800 feet; and
3) at AXMUL, intercept glideslope and continue descent.

Why would I turn right at CEPIN or even at MENLO to spend some time in
the hold at DUMBA, except perhaps if I arrived prior to my filed ETA?


I wouldn't turn right at CEPIN even if I was ahead of my filed ETA. There's
no way to turn at MENLO, the procedure goes only to CEPIN from MENLO.

In article . net,
"Steven P. McNicoll" wrote:

"rps" wrote in message
oups.com...

I'm still confused. Assuming the following facts, how would you fly
the ILS RWY 28R at KSFO
....
I wouldn't turn right at CEPIN even if I was ahead of my filed ETA. There's
no way to turn at MENLO, the procedure goes only to CEPIN from MENLO.

Turning left at CEPIN certainly makes intuitive sense, but if that's the
right thing to do then why is MENLO-CEPIN not marked NoPT?
There are three (and only three) possibilities:

1. You are required to turn right at CEPIN and hold at DUMBA.
2. The absence of a NoPT designation is meaningless.
3. MENLO-CEPIN should be marked NoPT; the fact that it isn't is a
mistake.

Given that the ILS 28L approach has an almost identical segment
(MENLO-HEMAN) that IS marked NoPT my money is on #3.

rg

"Ron Garret" wrote in message
...

Turning left at CEPIN certainly makes intuitive sense, but if that's the
right thing to do then why is MENLO-CEPIN not marked NoPT?
There are three (and only three) possibilities:

1. You are required to turn right at CEPIN and hold at DUMBA.
2. The absence of a NoPT designation is meaningless.
3. MENLO-CEPIN should be marked NoPT; the fact that it isn't is a
mistake.

Given that the ILS 28L approach has an almost identical segment
(MENLO-HEMAN) that IS marked NoPT my money is on #3.


I don't see why MENLO..HEMAN should be marked NoPT. If you're beginning the
ILS RWY 28R at MENLO you're not going to cross the holding fix DUMBA.

Another example from the same plate:

http://www.naco.faa.gov/d-tpp/0510/00375I28R.PDF

You've not been given "vectors to final".
You're established on the approach from the IAF FAITH.
You're at 4100 feet.
You fly over DUMBA.
The leg from FAITH to DUMBA is NOT marked NoPT.

I'm in the camp which thinks (hopes?) that a turn in the hold at DUMBA
is not logical nor required.

Three questions:

a) does anyone think a turn in the hold at DUMBA is required? If so,
why?

b) should the leg from FAITH to DUMBA be marked "NoPT"?

Tim.

PS. I think Chip Jones posted a very similar example a while back when
he got a surprise when the pilot did do a turn. I'll see if I can
find the reference.


On Mon, 03 Oct 2005 09:16:54 GMT, "Steven P. McNicoll"
wrote:


"Ron Garret" wrote in message
...

Turning left at CEPIN certainly makes intuitive sense, but if that's the
right thing to do then why is MENLO-CEPIN not marked NoPT?
There are three (and only three) possibilities:

1. You are required to turn right at CEPIN and hold at DUMBA.
2. The absence of a NoPT designation is meaningless.
3. MENLO-CEPIN should be marked NoPT; the fact that it isn't is a
mistake.

Given that the ILS 28L approach has an almost identical segment
(MENLO-HEMAN) that IS marked NoPT my money is on #3.


I don't see why MENLO..HEMAN should be marked NoPT. If you're beginning the
ILS RWY 28R at MENLO you're not going to cross the holding fix DUMBA.

In article . net,
"Steven P. McNicoll" wrote:

"Ron Garret" wrote in message
...

Turning left at CEPIN certainly makes intuitive sense, but if that's the
right thing to do then why is MENLO-CEPIN not marked NoPT?
There are three (and only three) possibilities:

1. You are required to turn right at CEPIN and hold at DUMBA.
2. The absence of a NoPT designation is meaningless.
3. MENLO-CEPIN should be marked NoPT; the fact that it isn't is a
mistake.

Given that the ILS 28L approach has an almost identical segment
(MENLO-HEMAN) that IS marked NoPT my money is on #3.


I don't see why MENLO..HEMAN should be marked NoPT.

It's marked NoPT to make it clear that you should turn left at HEMAN
instead of right. (Isn't that obvious?)

If you're beginning the
ILS RWY 28R at MENLO you're not going to cross the holding fix DUMBA.

You will if you turn right at HEMAN.

rg