On Fri, 10 Mar 2006 02:10:56 GMT, "Dan Wegman"
wrote:


"Barry" wrote in message
...
unless the navigational station is the primary for the approach (which
could be true for ADF, but not DME).

Except, of course, for the famous VOR/DME OR TACAN Z RWY 15 approach at
Martin State:

http://www.naco.faa.gov/d-tpp/0602/05222VDTZ15.PDF
Are you saying that you can't use the GPS in lieu of DME for that
approach?
Why not?

Yes, because the DME is the "principal instrument approach navigation
source" - that approach is a DME arc to the runway.



A subtle but important observation! Have you won any bets with that one?

Might I ask what makes that approach any different than the ILS/DME
RWY 2 approach APOA uses as the sample in their "Use of GPS in lieu"
piece (
http://www.aopa.org/whatsnew/air_tra...u.html#figurea )
where they say "DME arcs associated with instrument approaches may be
flown using GPS distance provided the DME transmitter, on which the
arc is based, is identified in the GPS database (see Figure A)." ?

Course if we're talking about determining an alternate while planning
than yea, no substitution - but if the station is in the database and
you're shooting the approach it seems to fit the substitution rules to
me?