Nathan Young wrote:
On Fri, 10 Mar 2006 04:34:29 -0800, scott moore
wrote:

Now that the WAAS minimums are going to be 200, same as
ILS, and the first WAAS approaches are going to be
overlaid over standard ILS approaches, the question
arises:

Which approach makes more sense to an ILS runway, use
of the ILS, or the WAAS?

Before you say "good ole ILS", consider: WAAS is going
to have many characteristics of an ideal precision system.
No false glideslopes, infinite range, no backcourse image,
etc.

Although my aircraft isn't so equipped (yet) - WAAS.

WAAS + a GPSS equipped A/P would have the ability to steer you from
cruise to the DH.

Question: When a WAAS and ILS approach co-exist for the same runway,
does the FAA make the WAAS approach so it is an exact overlay of the
ILS? It would be nice to run the WAAS approach on the GPS, and have
NAV2 tracking the ILS as a backup.

From the Aopa article on the same subject, I gather it is, but I
could be interpreting it wrong (it does not go into it in much
detail):

http://www.aopa.org/whatsnew/newsite...60307waas.html

I have used the 2nd radio LOC to follow a GPS approach, they seem to
track as you would expect, that is, close, but not identical, perhaps
a half dot off.

I'd like to do the 2nd ILS monitor thing as well, but it would require
an upgrade to my 2nd radio, which is the crappy original ARC radio
without a glideslope.