"Peter R." wrote in message
...

Admittedly I didn't read the entire circular (I have a Garmin GNS430), but
my quick skim of it seemed to indicate that the non-compliant models are
no longer allowed to use GPS in lieu of ADF or DME, where that is
applicable, unless alternate instructions are provided by ATC. This would
imply that for home-grown RNAV approaches these units would still be
legal. Did I interpret incorrectly?


I didn't read the entire AC either, but I don't see how you or AOPA
conclude that use of GPS to substitute for ADF or DME is now limited in all
cases to the cited Garmin units. The subject of AC 90-100A is "U.S.
Terminal and En Route Area Navigation (RNAV) Operations." The AC says it
"applies to operation on U.S. Area Navigation (RNAV) routes (Q-routes and
T-routes), Departure Procedures (Obstacle Departure Procedures and Standard
Instrument Departures), and Standard Terminal Arrivals (STARs)." The AOPA
letter states, "Pilots have removed ADF and DME systems from their aircraft
and they will no longer have access to any conventional approaches that
require them." I can find nothing that suggests the previous approval to
substitute GPS for ADF or DME has been rescinded for IAPs.