Substitute DME for GPS?

Hi all,

a question that has probably been asked before, but I couldn't find it
in Google:

Is it allowed to use an IFR-approach-certified GPS instead of a DME in
a LOC-DME or VOR-DME approach that does not have a GPS-overlay?

Thanks!

--
Thomas Borchert (EDDH)

DME distances will be greater than GPS distances due to slant-range.

Thomas Borchert wrote:
Hi all,

a question that has probably been asked before, but I couldn't find it
in Google:

Is it allowed to use an IFR-approach-certified GPS instead of a DME in
a LOC-DME or VOR-DME approach that does not have a GPS-overlay?

Thanks!

Thomas Borchert ) wrote:

Is it allowed to use an IFR-approach-certified GPS instead of a DME in
a LOC-DME or VOR-DME approach that does not have a GPS-overlay?

YEs. See AIM 1-1-19. Global Positioning System (GPS), subsection (f).

http://www.faa.gov/ATPubs/AIM/Chap1/aim0101.html#1-1-19

A quote:

--- quote ---

(f) Use of GPS in lieu of ADF and DME

1. Subject to the restrictions below, operators in the U.S. NAS are
authorized to use GPS equipment certified for IFR operations in place of
ADF and/or DME equipment for en route and terminal operations. For some
operations there is no requirement for the aircraft to be equipped with
an ADF or DME receiver, see subparagraphs f6(g) and (h) below. The
ground-based NDB or DME facility may be temporarily out of service
during these operations. Charting will not change to support these
operations.

---- end quote ---

--
Peter

"Thomas Borchert" wrote in message
...
Hi all,

a question that has probably been asked before, but I couldn't find it
in Google:

Is it allowed to use an IFR-approach-certified GPS instead of a DME in
a LOC-DME or VOR-DME approach that does not have a GPS-overlay?



See AIM 1-1-19(f)

john smith wrote:
DME distances will be greater than GPS distances due to slant-range.

On approach, you're at low altitude and the difference will be in the noise.


Thomas Borchert wrote:

Hi all,

a question that has probably been asked before, but I couldn't find it
in Google:

Is it allowed to use an IFR-approach-certified GPS instead of a DME in
a LOC-DME or VOR-DME approach that does not have a GPS-overlay?
Thanks!

Thomas Borchert wrote in
:

Hi all,

a question that has probably been asked before, but I couldn't find it
in Google:

Is it allowed to use an IFR-approach-certified GPS instead of a DME in
a LOC-DME or VOR-DME approach that does not have a GPS-overlay?

Thanks!


Yes, you may, but you have to aware that the GPS may not contain the LOC
station in its database. VOR stations should be fine.


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Andrew Sarangan wrote:
Thomas Borchert wrote in
:


Hi all,

a question that has probably been asked before, but I couldn't find it
in Google:

Is it allowed to use an IFR-approach-certified GPS instead of a DME in
a LOC-DME or VOR-DME approach that does not have a GPS-overlay?

Thanks!



Yes, you may, but you have to aware that the GPS may not contain the LOC
station in its database. VOR stations should be fine.

And if that's the case you look at the little numbers on the approach
plate that give distances along final. That's also how you can
determine the MAP on a VOR approach when the VOR is located off the airport.

Stan,

Thanks to all!

--
Thomas Borchert (EDDH)

True. But if there is a fix in the approach that is defined by a distance
from something that is in the GPS database, you can use that fix and the
distance from it as a substitute for the LOC distance. That works, but in my
opinion does require advance planning to calculate the relevant distances
from that fix and write them down. It's way too easy to make a mistake to do
the figuring in real time during the approach.

"Andrew Sarangan" wrote in message
. 4...

Yes, you may, but you have to aware that the GPS may not contain the LOC
station in its database. VOR stations should be fine.

"Thomas Borchert" wrote in message
...
Hi all,

a question that has probably been asked before, but I couldn't find it
in Google:

Is it allowed to use an IFR-approach-certified GPS instead of a DME in
a LOC-DME or VOR-DME approach that does not have a GPS-overlay?


I have never seen an approach certified GPS that did not have all the
intermediate waypoints for flying such an approach stored in its database.
Instead of your having to figure out that XYZZY is 5 DME from the airport,
the GPS should be giving you distance to XYZZY directly, automatically
cycling to the next waypoint upon reaching XYZZY. At least, that is what the
Garmin and Bendix-King GPSs that I am familiar with do.

AIM does say that approach certified GPS may be used in lieu of DME for
approaches.