GPS distance VS DME distance

[b350capt]

if you further read F.1 it clearly states the operations approved for GPS in lieu of dme/adf which is what i posted earlier. Approach substitutions are NOT oh that list. Also if you read the note listed after 1-1-19(f)(1)(a)(6) you will see the following -
NOTE-
This approval does not alter the conditions and requirements for use of GPS to fly existing nonprecision instrument approach procedures as defined in the GPS approach overlay program.

Here is what 1-1-19(e)(3) says
3. The GPS Approach Overlay Program is an authorization for pilots to use GPS avionics under IFR for flying designated nonprecision instrument approach procedures, except LOC, LDA, and simplified directional facility (SDF) procedures. These procedures are now identified by the name of the procedure and "or GPS" (e.g., VOR/DME or GPS RWY 15). Other previous types of overlays have either been converted to this format or replaced with stand-alone procedures. Only approaches contained in the current onboard navigation database are authorized. The navigation database may contain information about nonoverlay approach procedures that is intended to be used to enhance position orientation, generally by providing a map, while flying these approaches using conventional NAVAIDs. This approach information should not be confused with a GPS overlay approach (see the receiver operating manual, AFM, or AFM Supplement for details on how to identify these approaches in the navigation database).

I think it makes it clear that GPS substitutions for approaches on non-overlay approaches are not allowed, and are advisory only. of course thats only my thinking, lol

 

[satpak77]

basically, if the FAA allowed GPS "DME" on the approach, it would be stated as such. VOR/DME means, well, VOR/DME

b350capt: good info from you....all good points

later guys

 

[midlifeflyer]

if you further read F.1 it clearly states the operations approved for GPS in lieu of dme/adf which is what i posted earlier. Approach substitutions are NOT oh that list.

Sure they are:

==============================
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.
(a) Operations allowed:
(1) Determining the aircraft position over a DME fix. GPS satisfies the 14 CFR Section 91.205(e) requirement for DME at and above 24,000 feet mean sea level (MSL) (FL 240).
==============================

Also if you read the note listed after 1-1-19(f)(1)(a)(6) you will see the following -
NOTE-
This approval does not alter the conditions and requirements for use of GPS to fly existing nonprecision instrument approach procedures as defined in the GPS approach overlay program.

We are reading this stuff two completely different ways. I read the italics as saying what I said before - you can't fly an NDB approach just using a GPS.

But you =can= identify an NDB or DME fix (say an OM) on a VOR approach with GPS (so long as you are using VOR for course guidance).

The difference is course guidance vs fix location. You cannot use the GPS for course guidance (overlay) unless the approach plate says "GPS" on it. But you =can= use GPS to locate fixes, even if they are DME or ADF-based and even if you are flying a VOR "terminal procedure," AIM 1-11-19.f.1.c. even tells you how.

That's why new piston singles (not glass) come IFR equipped with VOR/LOC/Glideslope, but no DME or ADF receiver.

I really think you are incorrect on this. As I recall, AOPA worked with the FAA on this specific issue years ago.


==============================
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.
(a) Operations allowed:
(1) Determining the aircraft position over a DME fix. GPS satisfies the 14 CFR Section 91.205(e) requirement for DME at and above 24,000 feet mean sea level (MSL) (FL 240).
==============================

 

[Flysher]

Id have to say I agree with midlifeflyer here. Alot of new airplanes are coming without DME and just IFR GPS, so how are these aircraft supposed to determine distance on the slew of approaches out there that require it?

 

[b350capt]

again....terminal and approach are two SEPERATE things

 

[GVJeff]

again....terminal and approach are two SEPERATE things

The word is separate.

 

[satpak77]

AOPA article

http://www.aopa.org/whatsnew/air_traffic/gps_in_lieu.html

 

[b350capt]

well, i hate to do this, but i think i must admit that i think i am wrong, lol. In closer looks at the IFR handbook, it seems that the principle airport may have GPS substitute for DME regardless of approach definition. In this case (approach in question) GPS can be used to substitute the DME, but not used to fly the approach. The exception is if an alternate is required, GPS substitution is NOT allowed if the aircraft is not equiped with DME or ADF. Learn somethin new everyday, lol! Thanks guys for the conversation guys, and good job midlife.....

 

[b350capt]

and i can't spell, lol

 

[FlyingSkip]

I'll tell you what---I gotta give it to b350!!! This guy can not only admit when he's mistaken, but he has a sense of humor! You really need to be over on CAAM rather than here with this group of never-wrong, never laugh misfits!!! Just kidding, just kidding!

B350---hero in my book. Nice to know I'm sharing the skies with people who have a personality.