GPS Question

I thought I understood this, but maybe not. GPS systems were certified
for approaches after I got my instrument ticket, so my knowledge is
more anecdotal than from actual training.

Can an approach-certified GPS be used to substitute for NDB and DME
during an approach (or even en route)? What if the approach says ADF
Required or DME Required? My understanding of the AIM is that you can
only use the GPS as a substitute when there is a published GPS overlay
for the approach.

(My question is about the legality and not about whether you'd be close
enough.)

On 03/09/06 11:35, rps wrote:
I thought I understood this, but maybe not. GPS systems were certified
for approaches after I got my instrument ticket, so my knowledge is
more anecdotal than from actual training.

Can an approach-certified GPS be used to substitute for NDB and DME
during an approach (or even en route)? What if the approach says ADF
Required or DME Required? My understanding of the AIM is that you can
only use the GPS as a substitute when there is a published GPS overlay
for the approach.

(My question is about the legality and not about whether you'd be close
enough.)


The AIM has a section devoted to the use of GPS in lieu of ADF and DME,
which will answer your question, and much more ;-)

Go to section 1-1-19, and look for "Use of GPS in lieu of ADF and DME".

The short answer is yes, you can use GPS as a replacement for ADF and DME
unless the navigational station is the primary for the approach (which
could be true for ADF, but not DME).

So, if you're flying an NDB approach, you could not use the GPS as a
replacement for the NDB ground station.

However, if you're flying an approach that requires DME, or an NDB to
identify the OM, you can use the GPS to provide that information.


--
Mark Hansen, PP-ASEL, Instrument Airplane
Cal Aggie Flying Farmers
Sacramento, CA

Can an approach-certified GPS be used to substitute for NDB and DME
during an approach (or even en route)? What if the approach says ADF
Required or DME Required? My understanding of the AIM is that you can
only use the GPS as a substitute when there is a published GPS overlay
for the approach.

My understanding is that it can, except for an NDB approach. If the NDB
approach has a GPS overlay, then it is a GPS approach anyway.

Jose
--
Money: what you need when you run out of brains.
for Email, make the obvious change in the address.

Mark Hansen wrote:

So, if you're flying an NDB approach, you could not use the GPS as a
replacement for the NDB ground station.

Here in the lower 48 states, the NDB approach is fast going the way of the
Dodo bird. Every Jepp update I have received over the last 6 months seems
to require the removal of more NBD approaches than those I replace.

--
Peter

unless the navigational station is the primary for the approach (which
could be true for ADF, but not DME).

Except, of course, for the famous VOR/DME OR TACAN Z RWY 15 approach at Martin
State:

http://www.naco.faa.gov/d-tpp/0602/05222VDTZ15.PDF

On 03/09/06 12:51, Barry wrote:
unless the navigational station is the primary for the approach (which
could be true for ADF, but not DME).

Except, of course, for the famous VOR/DME OR TACAN Z RWY 15 approach at Martin
State:

http://www.naco.faa.gov/d-tpp/0602/05222VDTZ15.PDF



Are you saying that you can't use the GPS in lieu of DME for that approach?
Why not?

--
Mark Hansen, PP-ASEL, Instrument Airplane
Cal Aggie Flying Farmers
Sacramento, CA

"Mark Hansen" wrote in message
...
On 03/09/06 11:35, rps wrote:
I thought I understood this, but maybe not. GPS systems were certified
for approaches after I got my instrument ticket, so my knowledge is
more anecdotal than from actual training.

Can an approach-certified GPS be used to substitute for NDB and DME
during an approach (or even en route)? What if the approach says ADF
Required or DME Required? My understanding of the AIM is that you can
only use the GPS as a substitute when there is a published GPS overlay
for the approach.

(My question is about the legality and not about whether you'd be close
enough.)


The AIM has a section devoted to the use of GPS in lieu of ADF and DME,
which will answer your question, and much more ;-)

Go to section 1-1-19, and look for "Use of GPS in lieu of ADF and DME".

The short answer is yes, you can use GPS as a replacement for ADF and DME
unless the navigational station is the primary for the approach (which
could be true for ADF, but not DME).

So, if you're flying an NDB approach, you could not use the GPS as a
replacement for the NDB ground station.

However, if you're flying an approach that requires DME, or an NDB to
identify the OM, you can use the GPS to provide that information.


--
Mark Hansen, PP-ASEL, Instrument Airplane
Cal Aggie Flying Farmers
Sacramento, CA

Except for flying an approach at the alternate:

Ref: AIM 1-1-19, paragraph f.1.(b)(8)
Restrictions

"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."

They've gotten rid of a bunch of NDB approaches, but there were still 1,283
left as of 10/27/05.



"Peter R." wrote in message
...
Mark Hansen wrote:

So, if you're flying an NDB approach, you could not use the GPS as a
replacement for the NDB ground station.

Here in the lower 48 states, the NDB approach is fast going the way of the
Dodo bird. Every Jepp update I have received over the last 6 months seems
to require the removal of more NBD approaches than those I replace.

--
Peter

Except for flying an approach at the alternate:

Nope. Except for determining a legal alternate. Once you are in the
air, if you need to go to =an= alternate, it doesn't have to be your
filed one, and even if you decide to go to your filed alternate, there
are no special GPS rules. You can use the approach-certified GPS as a
substitute for NDB and DME, except for an NDB approach, just like your
original destination.

Jose
--
Money: what you need when you run out of brains.
for Email, make the obvious change in the address.

Except for flying an approach at the alternate:

Ref: AIM 1-1-19, paragraph f.1.(b)(8)
Restrictions

"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."


Not so. One can still fly a GPS approach at the alternate. You just need the
other equipment installed. If you have approved WAAS avionics, you may plan
to use any instrument approach authorized for use with WAAS avionics at a
required alternate.

Karl
"Curator" N185KG