Yet more GPS substitution questions

Yet another GPS substitution question...

It's a given that you can't use GPS to shoot an approach labled "ADF
blah" unless it says "ADF or GPS blah", but how do the alternate
rules really work? The regs say that I have to have an approach that
I'm equipped for other than GPS at the alternate airport, like an ILS.
Am I correct in believing that if you need the GPS for DME, or to
identify missed approach holding points on the ILS, you still can't
use that as an alternate because the GPS is used in some way to
complete the approach?

Secondly, how about shooting this approach (VOR/DME 21 at Minuteman -
Stow, MA) - http://avn.faa.gov/d-tpp/0501/05764VD21.PDF . Assuming
that I'm shooting this as a primary approach (not my alternate), and
the aircraft doesn't have DME, what can I do with this approach?
Wouldn't I technically have to fly the approach with the HSI in VOR
mode (it doesn't say VOR or GPS, it says VOR/DME, and without an
overlay the GPS is only advisory)? But the DME is based off of the
MHT VOR. If I load the procedure into the GPS and go past the 'not a
gps approach, only advisory use' warning, now my distances are going
to be based on the waypoints the system loads up - EGORE, RW21, EGORE.
Since loading the approach for non-GPS or non-overlay approaches does
come up with the "advisory only" warning, how does it work to legally
use the GPS on this approach? It's not giving me DME from MHT, it's
not even giving me DME from EGORE, it's giving me DME to RW21, a
non-five-letter name waypoint (which should be coincident to the
threshold of the runway, and thus 25.1NM from MHT), but with the
"advisory only" warning, course guidance coming from the VOR, and the
distance references coming from something other than the DME origin
for the approach, how does this approach work? I'm sure I'm missing
something here, just curious what it is.

TIA.

On Fri, 11 Feb 2005 00:29:41 GMT, wrote:

On Thu, 10 Feb 2005 19:24:36 -0500, Peter Clark
wrote:

Secondly, how about shooting this approach (VOR/DME 21 at Minuteman -
Stow, MA) - http://avn.faa.gov/d-tpp/0501/05764VD21.PDF . Assuming
that I'm shooting this as a primary approach (not my alternate), and
the aircraft doesn't have DME, what can I do with this approach?


What difference does "alternate" make?

When it comes to actually flying the approach, "alternate" is a
meaningles term..

Since this approach is labeled as N/A as an alternate, and the first
question specifically dealt with alternate requirements, I was trying
to head off someone saying "But you can't use that as an alternate
anyway".....

wrote in message
...
On Thu, 10 Feb 2005 19:24:36 -0500, Peter Clark
wrote:

Secondly, how about shooting this approach (VOR/DME 21 at Minuteman -
Stow, MA) - http://avn.faa.gov/d-tpp/0501/05764VD21.PDF . Assuming
that I'm shooting this as a primary approach (not my alternate), and
the aircraft doesn't have DME, what can I do with this approach?


What difference does "alternate" make?

When it comes to actually flying the approach, "alternate" is a
meaningles term..

Actually, I think Peter asked an interesting question. The AIM says:

(8) For TSO-C129/129A users, any required alternate airport must still have
an approved instrument approach procedure other than GPS that is anticipated
to be operational and available at the estimated time of arrival, and which
the aircraft is equipped to fly. If the non-GPS approaches on which the
pilot must rely require DME or ADF, the aircraft must be equipped with DME
or ADF avionics as appropriate.

This seems to say that substitution of GPS for DME or ADF is not authorized
for the purpose of determining whether an airport is suitable for filing as
an alternate.

Agreed, for actually flying the approach, it doesn't matter, but for filing,
it is interesting.

On Thu, 10 Feb 2005 19:08:47 -0600, "Stan Prevost"
wrote:


wrote in message
.. .
On Thu, 10 Feb 2005 19:24:36 -0500, Peter Clark
wrote:

Secondly, how about shooting this approach (VOR/DME 21 at Minuteman -
Stow, MA) - http://avn.faa.gov/d-tpp/0501/05764VD21.PDF . Assuming
that I'm shooting this as a primary approach (not my alternate), and
the aircraft doesn't have DME, what can I do with this approach?


What difference does "alternate" make?

When it comes to actually flying the approach, "alternate" is a
meaningles term..

Actually, I think Peter asked an interesting question. The AIM says:

(8) For TSO-C129/129A users, any required alternate airport must still have
an approved instrument approach procedure other than GPS that is anticipated
to be operational and available at the estimated time of arrival, and which
the aircraft is equipped to fly. If the non-GPS approaches on which the
pilot must rely require DME or ADF, the aircraft must be equipped with DME
or ADF avionics as appropriate.

Which is where I was coming up with my understanding for the answer to
question number 1 - since the missed approach holding point is a NDB,
even though the approach is an ILS, without an ADF onboard it
"require[s] DME or ADF" so you can't file there as an alternate.

Or, are we saying that as long as you can find an airport without
"Alternate minimums N/A" with a VOR approach which only uses
cross-radials to identify the step-downs and holding fix, go ahead and
file that airport for the alternate, and in the event that you have to
divert you can still shoot a GPS or other approach which requires the
use of the GPS when you get there? If so, what is the requirement to
have a non-GPS shootable alternate available really protecting
against? Lack of RAIM?

Stan Prevost wrote:

wrote in message
...

On Thu, 10 Feb 2005 19:24:36 -0500, Peter Clark
wrote:


Secondly, how about shooting this approach (VOR/DME 21 at Minuteman -
Stow, MA) - http://avn.faa.gov/d-tpp/0501/05764VD21.PDF . Assuming
that I'm shooting this as a primary approach (not my alternate), and
the aircraft doesn't have DME, what can I do with this approach?


What difference does "alternate" make?

When it comes to actually flying the approach, "alternate" is a
meaningles term..


Actually, I think Peter asked an interesting question. The AIM says:

(8) For TSO-C129/129A users, any required alternate airport must still have
an approved instrument approach procedure other than GPS that is anticipated
to be operational and available at the estimated time of arrival, and which
the aircraft is equipped to fly. If the non-GPS approaches on which the
pilot must rely require DME or ADF, the aircraft must be equipped with DME
or ADF avionics as appropriate.

This seems to say that substitution of GPS for DME or ADF is not authorized
for the purpose of determining whether an airport is suitable for filing as
an alternate.

Yes, unless your GPS is WAAS capable, then this doesn't apply.

On Fri, 11 Feb 2005 01:44:14 GMT, wrote:

You are free to go anywhere (including your alternate) and fly any
approach for which you have the appropriate equipment on board to fly
that approach, regardless of what the requirements are to select the
alternate before departure.

OK, then why have the requirements that prohibit GPS substitution when
picking an alternate for filing?

Getting out of the alternate rathole, any thoughts about the general
rules of GPS substitution, specifically applying them to the questions
I had on the Minuteman approach?

Thanks.

I haven't read all the posts, but I'll through this out there.....

Since it's not a GPS approach or even a GPS overlay on the VOR, you're not
flying to or sequencing to the waypoints on this VOR approach, you're flying
away from MHT, so that's what you need to measure useing DME or GPS.
I'd go Direct TO MHT, or make MHT the active waypoint, put the GPS in OBS
mode... tune in the 210 bearing from MHT into the GPS or your OBS so it drew
my outbound course and it would also measure my distance from MHT along that
course.... then I'd fly the VOR needle because it's a VOR approach and use
the GPS from MHT for dme.
Jim

"Newps" wrote in message
...


Stan Prevost wrote:

wrote in message
...

On Thu, 10 Feb 2005 19:24:36 -0500, Peter Clark
wrote:


Secondly, how about shooting this approach (VOR/DME 21 at Minuteman -
Stow, MA) - http://avn.faa.gov/d-tpp/0501/05764VD21.PDF . Assuming
that I'm shooting this as a primary approach (not my alternate), and
the aircraft doesn't have DME, what can I do with this approach?


What difference does "alternate" make?

When it comes to actually flying the approach, "alternate" is a
meaningles term..


Actually, I think Peter asked an interesting question. The AIM says:

(8) For TSO-C129/129A users, any required alternate airport must still
have an approved instrument approach procedure other than GPS that is
anticipated to be operational and available at the estimated time of
arrival, and which the aircraft is equipped to fly. If the non-GPS
approaches on which the pilot must rely require DME or ADF, the aircraft
must be equipped with DME or ADF avionics as appropriate.

This seems to say that substitution of GPS for DME or ADF is not
authorized for the purpose of determining whether an airport is suitable
for filing as an alternate.

Yes, unless your GPS is WAAS capable, then this doesn't apply.


Yes, the AIM statement begins with reference to the non-WAAS TSO.

I think I'd interpret "as appropriate" as meaning that the GPS
essentially meets the definition of "DME or ADF avionics", since the
rules say it can be substituted for such,

I do not concur, and believe such an interpretation is contrary to the
intent if the statement.

(8) For TSO-C129/129A users, any required alternate airport must still
have
an approved instrument approach procedure other than GPS that is
anticipated
to be operational and available at the estimated time of arrival, and
which
the aircraft is equipped to fly. If the non-GPS approaches on which
the
pilot must rely require DME or ADF, the aircraft must be equipped with
DME
or ADF avionics as appropriate.

I believe the last statement means what it says - that for purposes of
selecting a valid alternate, one must select an approach that can be
completed without reliance on GPS.

Michael

On 11 Feb 2005 11:23:14 -0800, "Michael"
wrote:

I think I'd interpret "as appropriate" as meaning that the GPS
essentially meets the definition of "DME or ADF avionics", since the
rules say it can be substituted for such,

I do not concur, and believe such an interpretation is contrary to the
intent if the statement.

(8) For TSO-C129/129A users, any required alternate airport must still
have
an approved instrument approach procedure other than GPS that is
anticipated
to be operational and available at the estimated time of arrival, and
which
the aircraft is equipped to fly. If the non-GPS approaches on which
the
pilot must rely require DME or ADF, the aircraft must be equipped with
DME
or ADF avionics as appropriate.

I believe the last statement means what it says - that for purposes of
selecting a valid alternate, one must select an approach that can be
completed without reliance on GPS.

Michael


"What it says" depends on how one interprets "as appropriate".

(a) Since it is "appropriate" to substitute GPS for DME and ADF on
non-GPS approaches, then it's acceptable as far as I am concerned.
Furthermore, (b) The aircraft is "equipped to fly" the non-GPS
approach.and (c) they'll never catch me anyway even if I'm wrong.