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Old July 16th 03, 12:17 PM
Richard Kaplan
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Default Garmin Behind the Curve on WAAS GPS VNAV Approaches




"Scott Moore" wrote in message
...
Speaking only for myself, its pretty damm confusing exactly what would be
done with WAAS even if implemented. Garmins' other units that accept


WAAS is now implemented and IFR approved as of the past week.

If a receiver were approved for WAAS approaches, then TODAY you could use
VNAV/LNAV miniums on GPS RNAV approaches instead of LNAV minimums.
Presumably (though I am not certain) a VNAV/LNAV GPS RNAV approach would be
considered a precision approach. UPSAT's CNX80 web page touts the airports
you have access to today with WAAS; yet the version of the POH supplement
posted on their site says in the legal fineprint that precision approaches
are NOT permitted. So I am not certain if you can or cannot fly VNAV/LNAV
GPS approach mininums TODAY on a CNX-80.

What I would like to see from Garmin is a controlled descent option
on non-precision GPS approaches, which would be perfectly legal to
implement right now (because it is inside the "dive and drive"


If you want to do this as a backup to other navigation, you can do this now
with the VNAV function on the Garmin 430/530, albeit not yet with WAAS.

Nonetheless, there is a big question whether this will make sense for an
approach not explicitly designed as a precision approach. Many
non-precision approaches have a missed approach point from which a suitable
straight-in landing cannot be made; so you could well have a controlled
descent to the middle of the field an then in turn have to circle.

--
Richard Kaplan, CFII

www.flyimc.com