"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.