Change in AIM wording concerning procedure turn

"S Narayan" wrote in message
news:1128031835.1bb41b72ab7f6a781ad35e5e7380cc8f@t eranews...

"Gary Drescher" wrote in message
...
"Kris Kortokrax" wrote in message
...
New text

5-4-9. Procedure Turn
a. A procedure turn is the maneuver prescribed to perform a course
reversal to establish the aircraft inbound on an intermediate or final
approach course. The procedure turn or hold in lieu of procedure turn is
a required maneuver

(the following text is underlined in the AIM)
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 new text strikes me as entirely ambiguous. It could mean:

"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."

Or it could mean:

"The procedure turn is a required maneuver, unless: 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; or 5) there is (for any reason) no necessity to perform a
course reversal."

The two interpretations differ if conditions 1-4 don't obtain, but the
pilot (and/or controller) thinks there's no need for a course reversal.
The first interpretation says the procedure turn is still required in
that case; the second one says the opposite.

As a previous poster noted, they need to define how many degrees of turn
constitutes a "course reversal". Then it would clear and unambiguous.
Otherwise it is still is open to interpretation depending on the
aircraft/speed etc.

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).

A secondary point (mentioned earlier in the thread) is that the TERPS
standards can require a PT on the basis of altitude, even if you're already
aligned with the final approach course. Moreover, it would make little sense
for the AIM to recapitulate the TERPS criteria for PTs in order to specify
the required action by pilots. Instead, the procedure chart itself should be
designed according to the TERPS criteria, and should specify a PT
requirement (by omitting the 'NoPT' designation) whenever those criteria are
met. The first interpretation above would be consistent with that intent.

--Gary