Do I need DME or ADF in an IFR-certified GPS panel?

On Thu, 09 Jun 2005 09:55:37 -0400, xyzzy wrote:

Ron Rosenfeld wrote:

On Wed, 08 Jun 2005 14:55:45 -0400, xyzzy wrote:


Doug wrote:


There is, in fact, a requirement to be able to fly the approach at your
alternate without the use of GPS. So having DME will assist you in
finding legal alternates that have VOR/DME approaches. This will allow
you to carry less fuel and more payload. Without DME or ADF, all you
can fly is a VOR approach, and if you have radar, an ILS or LOC (maybe
a few obscure others). Even then some ILS's require DME or ADF.

My home airport has an ILS approach with ADF required, but I just
figured I could use the GPS to substitute for the ADF. From what I
understand of the above, that's true but that also means my airport's
ILS approach is not a legal alternate for someone planning a GPS
somewhere else, do I understand that right? (I'm an instrument
student, still learning this stuff and have found this thread fascinating).


What is your home airport?


TTA, ILS RWY 3.


Some GPS units (GNS480) do NOT require that the the alternate have
something other than a GPS approach. But I'd like to look at your specific
approach to see if it would be legal to fly the ILS ADF approach there.

The other aproaches at TTA are GPS on both 3 and 21 and NDB on 3. So
basically an ADF is kinda important there. If you don't have an
approach certified GPS, you need one.

Well, according to my Jepp chart, TTA is NA for filing as an alternate, so
the ILS (or any other approach) would not be a legal alternate anyway.

For actually flying the ILS, an approach-approved GPS can substitute for
the NDB on that ILS approach.

Since the NDB Rwy 3 approach is not an overlay, an approach-approved GPS
could not fly it legally. This is not a loss as there is an RNAV(GPS) Rwy
3 approach which has lower minimums!

Best,

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

Ron Rosenfeld wrote:
On Thu, 09 Jun 2005 09:55:37 -0400, xyzzy wrote:


Ron Rosenfeld wrote:


On Wed, 08 Jun 2005 14:55:45 -0400, xyzzy wrote:



Doug wrote:



There is, in fact, a requirement to be able to fly the approach at your
alternate without the use of GPS. So having DME will assist you in
finding legal alternates that have VOR/DME approaches. This will allow
you to carry less fuel and more payload. Without DME or ADF, all you
can fly is a VOR approach, and if you have radar, an ILS or LOC (maybe
a few obscure others). Even then some ILS's require DME or ADF.

My home airport has an ILS approach with ADF required, but I just
figured I could use the GPS to substitute for the ADF. From what I
understand of the above, that's true but that also means my airport's
ILS approach is not a legal alternate for someone planning a GPS
somewhere else, do I understand that right? (I'm an instrument
student, still learning this stuff and have found this thread fascinating).


What is your home airport?


TTA, ILS RWY 3.



Some GPS units (GNS480) do NOT require that the the alternate have
something other than a GPS approach. But I'd like to look at your specific
approach to see if it would be legal to fly the ILS ADF approach there.

The other aproaches at TTA are GPS on both 3 and 21 and NDB on 3. So
basically an ADF is kinda important there. If you don't have an
approach certified GPS, you need one.


Well, according to my Jepp chart, TTA is NA for filing as an alternate, so
the ILS (or any other approach) would not be a legal alternate anyway.


Why do they designate airports NA for alternates? Is it perhaps because
a major class-C airport (RDU) is nearby and should be used as the
alternate instead?

Why do they designate airports NA for alternates? Is it perhaps because
a major class-C airport (RDU) is nearby and should be used as the
alternate instead?

They don't designate airports NA for alternates. They only designate
approaches NA for alternates. Pilots then sometimes refer to an
airport as being NA for alternates when they discover that all the
approaches are NA for alternates.

Often times, though, some approaches will be NA and others will not
be...

--
Cheers,
John Clonts
Temple, Texas
N7NZ

John Clonts wrote:

Why do they designate airports NA for alternates? Is it perhaps because
a major class-C airport (RDU) is nearby and should be used as the
alternate instead?


They don't designate airports NA for alternates. They only designate
approaches NA for alternates. Pilots then sometimes refer to an
airport as being NA for alternates when they discover that all the
approaches are NA for alternates.

Often times, though, some approaches will be NA and others will not
be...


Ok, why do they designate approaches NA for alternates (every approach
at this airport is so designated)?

Ok, why do they designate approaches NA for alternates (every approach
at this airport is so designated)?

The NACO approach books' legend explains thus:
[Black Triangle "A" NA] - Alternate minimums are Not Authorized due to
unmonitored facility or absence of weather reporting service

I understand that the "unmonitored facility" basically means that ATC
has no means of confirming that the facility (VOR, ILS, NDB, etc) is
working at a given time.


More info in this thread:
http://groups-beta.google.com/group/...a9031acc10224/

--
Cheers,
John Clonts
Temple, Texas
N7NZ

On 6/15/2005 09:51, John Clonts wrote:

Ok, why do they designate approaches NA for alternates (every approach
at this airport is so designated)?

The NACO approach books' legend explains thus:
[Black Triangle "A" NA] - Alternate minimums are Not Authorized due to
unmonitored facility or absence of weather reporting service

I understand that the "unmonitored facility" basically means that ATC
has no means of confirming that the facility (VOR, ILS, NDB, etc) is
working at a given time.

This still doesn't mean that the NA applies to the entire airport.
For example, at one of the local airports here, one of the approachs
is not authorized for use as an alternate when the tower is closed,
because it is not monitored. However, a different approach (at the
same airport) uses a VOR facility that is off-field, and it is
authorized as an alternate.

Of course, I'm an instrument student, so I may still be missing
something...



More info in this thread:
http://groups-beta.google.com/group/...a9031acc10224/



--
Mark Hansen, PP-ASEL, Instrument Student
Sacramento, CA

On Wed, 15 Jun 2005 10:05:07 -0700, Mark Hansen
wrote:

This still doesn't mean that the NA applies to the entire airport.
For example, at one of the local airports here, one of the approachs
is not authorized for use as an alternate when the tower is closed,
because it is not monitored. However, a different approach (at the
same airport) uses a VOR facility that is off-field, and it is
authorized as an alternate.

If there's no weather reporting, you're out of luck for the airport.

On Tue, 14 Jun 2005 11:10:33 -0400, xyzzy wrote:

Why do they designate airports NA for alternates? Is it perhaps because
a major class-C airport (RDU) is nearby and should be used as the
alternate instead?

Usually it is either because of unmonitored facilities or an absence of
weather reporting.

In point of fact, it is the approaches that are designated NA and not the
airport as a whole.

The fact that all of the approaches at TTA leads to an interesting
conundrum which get debated here from time to time.

Part 91 prescribes certain minima for an airport to be used as an
alternate. The way it reads (91.169c), if an instrument approach has been
published, then certain minima are required (depending on precision vs
non-precision, etc). However, if no instrument approach has been
published, then "the ceiling and visibility minima are those allowing
descent from the MEA, approach, and landing under basic VFR".

There's no exception for an airport which has published approaches, but
they're all marked NA for an alternate, as at TTA.

So, you're filed to RDU, and the weather requires an alternate. You obtain
"appropriate weather reports or weather forecasts, or a combination ..."
that indicate the weather at TTA will be severe clear at your time of
arrival. According to a strict reading of those regulations, you still
could not use it as an alternate; although it would be perfectly OK to use
some grass strip as an alternate. Makes no sense to me.


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

Ron Rosenfeld wrote:

So, you're filed to RDU, and the weather requires an alternate. You obtain
"appropriate weather reports or weather forecasts, or a combination ..."
that indicate the weather at TTA will be severe clear at your time of
arrival. According to a strict reading of those regulations, you still
could not use it as an alternate; although it would be perfectly OK to use
some grass strip as an alternate. Makes no sense to me.

You can't use it to satisfy the requirements for *filing* an alternate. You can
*use* whatever you want. Right?

Dave

Dave Butler wrote:

Ron Rosenfeld wrote:

So, you're filed to RDU, and the weather requires an alternate. You
obtain
"appropriate weather reports or weather forecasts, or a combination ..."
that indicate the weather at TTA will be severe clear at your time of
arrival. According to a strict reading of those regulations, you still
could not use it as an alternate; although it would be perfectly OK to
use
some grass strip as an alternate. Makes no sense to me.


You can't use it to satisfy the requirements for *filing* an alternate.
You can *use* whatever you want. Right?

Right, couldn't you file, say FAY, as an alternate then on your way
there when you break out cancel IFR and land at TTA?