GPS for NDB IAF on ILS?

Jim Burns wrote:

Thanks. Just got home and that was my interpretation of the AIM. As for
Jose's question, Newps answer concerns an NDB only approach, not a NDB GPS
overlay, and the reason being is that because in an NDB only approach you
must have the proper radios for the approach.

Which is baloney. My terminal/enroute GPS has the NDB in its database.
There's no reason I can't fly the NDB approach with my GPS. And I'll
fly it 100 times more accurately than anybody else with an ADF.

wrote:


Jose wrote:


The only time you can't use [GPS] is to substitute for an ADF on an NDB approach.

Any idea why that is?


Every NDB approach in the country was authorized as a GPS overlay approach when the
overlay program came into being. Since then, these authorizations have been withdrawn
for any particular runway end when a stand-alone RNAV (GPS) approach was published for
that runway end.

You cannot use GPS for any final approach segment that is not retreivable from the
database, and for good reason: no approach RAIM and no approach sensitivity.

Yeah and that's crucial condisering we're substituting for an ADF.

Newps wrote in
:

Yeah and that's crucial condisering we're substituting for an ADF.

And all the precision implied by an NDB approach. Bureaucracy lives!

--
Regards,

Stan

"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety." B. Franklin

Every NDB approach in the country was authorized as a GPS overlay approach when the
overlay program came into being. Since then, these authorizations have been withdrawn
for any particular runway end when a stand-alone RNAV (GPS) approach was published for
that runway end.

You cannot use GPS for any final approach segment that is not retreivable from the
database, and for good reason: no approach RAIM and no approach sensitivity.

I can see that for GPS approaches, where you are relying on all the
gee-whiz stuff (sequencing and such), but when the GPS is substituting
for a dumb radio needle, the approach segment doesn't have to be
anywhere to give good course guidance (which is all the NDB does anyway,
and it can be argued how good it is).

I still don't see the safety issue which would prompt the FAA to balk at
this substitution.

Jose
--
Nothing is more powerful than a commercial interest.
for Email, make the obvious change in the address.

Newps wrote:

Yeah and that's crucial condisering we're substituting for an ADF.

I guess that you mean that sarcastically. Without RAIM is is possible to have a sudden loss
of accuracy that would exceed the widths of an NDB final approach segment.

How likely? No more or less likely than having such a failure on a stand-alone RNAV IAP.

In any case, the criteria and conditions are set forth by Flight Standards, not me, not you,
and not ATC. ;-)

Jose wrote:

Every NDB approach in the country was authorized as a GPS overlay approach when the
overlay program came into being. Since then, these authorizations have been withdrawn
for any particular runway end when a stand-alone RNAV (GPS) approach was published for
that runway end.

You cannot use GPS for any final approach segment that is not retreivable from the
database, and for good reason: no approach RAIM and no approach sensitivity.

I can see that for GPS approaches, where you are relying on all the
gee-whiz stuff (sequencing and such), but when the GPS is substituting
for a dumb radio needle, the approach segment doesn't have to be
anywhere to give good course guidance (which is all the NDB does anyway,
and it can be argued how good it is).

I still don't see the safety issue which would prompt the FAA to balk at
this substitution.

I am not their advocate; just stating the facts as established by Flight Standards.

You might want to ask the man in charge, John McGraw, Director, Technical Programs Division,
Flight Standards Service, FAA, at their DC head-shed address.

wrote:

Beyond stupid.

I can use a cruddy old ADF receiver that was manufactured in the stone
age and provides no distance information with a highly innacurate
signal and questionable reliability, but the FAA won't "allow" the use
of a certified GPS.

My Garmin Street Map GPS beats an ADF hands down.


Your Garmin Street Map is just as accurate as a Garmin 500. It doesn't
have the integrity that 500 has, though.

Newps wrote:

Jim Burns wrote:

Thanks. Just got home and that was my interpretation of the AIM. As for
Jose's question, Newps answer concerns an NDB only approach, not a NDB GPS
overlay, and the reason being is that because in an NDB only approach you
must have the proper radios for the approach.

Which is baloney. My terminal/enroute GPS has the NDB in its database.
There's no reason I can't fly the NDB approach with my GPS. And I'll
fly it 100 times more accurately than anybody else with an ADF.

You guys should volunteer to represent AOPA at some of the industry meetings
that deal with all this stuff. Apparently, you guys are smarter than them
dim-witted AOPA technical reps.

In article , wrote:


wrote:

Beyond stupid.

I can use a cruddy old ADF receiver that was manufactured in the stone
age and provides no distance information with a highly innacurate
signal and questionable reliability, but the FAA won't "allow" the use
of a certified GPS.

My Garmin Street Map GPS beats an ADF hands down.


Your Garmin Street Map is just as accurate as a Garmin 500. It doesn't
have the integrity that 500 has, though.

How much integrity does an ADF have? I'll take an non-RAIM-ified
purple line over "it's still beeping" any day.

wrote:
You guys should volunteer to represent AOPA at some of the industry meetings
that deal with all this stuff. Apparently, you guys are smarter than them
dim-witted AOPA technical reps.

I'm sure the AOPA guys are plenty smart about technical stuff.
They're also plenty smart about political stuff and know how to
conservive political capital so they can win the fights that are
winnable and worth winning.

I can sit here and accuse the FAA of having a bad case of
recto-cranial inversion when it comes to using GPS for NDB approaches
with no ill effect. It makes me feel good to say it, it may make you
feel good to read it, but in the end it doesn't change anything.

If the AOPA guys did that, they'd lose cred with the feds, and their
efforts on regulatory issues would suffer as a result. I'm not giving
AOPA $100 a year (or whatever it is) to beat up the FAA about silly
**** like which radio I'm allowed to use to fly an approach into
Podunk Municipal. I'm giving them the money to make sure I can still
fly at all.