WAAS GPS approach question.

I thought the FAA approved the use of GPS for any NDB waypoint. A plane
without ADF can fly any ADF approach with a IFR approach certified GPS. GPS
waypoints can also be used in lue of ADF for missed approach holds, so you
can fly any approach that has "ADF required" without an ADF if you have an
IFR certified GPS.

"Matt Barrow" wrote in message
...

"Dico" wrote in message
oups.com...
Hello,

I read on the Garmin page that their 480 is Waas certified...so that
you can fly precision approaches without an ILS... what does this
mean exactly? If I'm coming into an airport with only an NDB
approach, can I use the 480's capabilites to fly a precision approach
and get down to a lower MDA/DH?


If the airport has only an NDB approach, how are you going to fly a GPS
approach of any sort?

On Fri, 21 Apr 2006 01:53:42 GMT, "soxinbox" wrote:

I thought the FAA approved the use of GPS for any NDB waypoint.

They did. But note the word "waypoint"


A plane
without ADF can fly any ADF approach with a IFR approach certified GPS. GPS
waypoints can also be used in lue of ADF for missed approach holds, so you
can fly any approach that has "ADF required" without an ADF if you have an
IFR certified GPS.

Note this from the AIM: (emphasis mine)

"(6) Charted requirements for ADF and/or DME can be met using the GPS
system, **EXCEPT** for use as the principal instrument approach navigation
source."

This would be true for a stand alone NDB approach (i.e. with no GPS
overlay); and for the primary DME approach at Martin State (near BWI).

If there is a published GPS overlay, that would be different. But not all
NDB approaches have GPS overlays.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

On 20 Apr 2006 15:24:09 -0700, "
wrote:

WAAS Approaches have vertical guidance but they
are not classified as "Precision"

Bill Hale

What makes you say that. The only definition I'm aware of (in the P/CG)
only requires that the approach provide electronic vertical guidance:

"PRECISION APPROACH PROCEDURE- A standard instrument approach procedure in
which an electronic glideslope/glidepath is provided"

I might argue that an LNAV approach with "advisory" vertical guidance does
not really meet that definition, but surely an LPV approach provides
"electronic vertical guidance".
Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)