Instrument Approaches GPS

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jesse

Touchdown! Greaser!
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Jesse
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jesse said:
The airplane in question has a Garmin 430 with dual nav/com (with glideslope). NO ADF, NO DME.

Take a look at the following approaches:
http://204.108.4.16/d-tpp/0810/00359IL35.PDF
http://204.108.4.16/d-tpp/0810/00359LBC17.PDF
http://204.108.4.16/d-tpp/0810/00359VDT35.PDF
http://204.108.4.16/d-tpp/0810/00359VT17.PDF

Are any of these approaches possible in the above airplane? If so, which ones, and why. If not, which ones, and why.
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OK, going one at a time, and why I think you picked each one:

1) ILS or LOC RWY 35: Says "ADF or TACAN Required" in the notes due to the IAF and MAHF both being NDB's.

2) LOC BC RWY 17: Says "ADF REQUIRED" in the plan view. IAF and MAHF are both NDB's again (same two, just reversed from the previous approach)

3) VOR/DME or TACAN RWY 35: Says "DME" right in the title of the approach, therefore denoting required equipment. DME arcs, and DME to identify several fixes.

4) VOR or TACAN RWY 17: Says "ADF or DME REQUIRED" on the plan view. You need one or the other to identify FOSRO, the FAF.

I'll take care of 'em all in one swell foop: AIM 1-1-19, Table 1-1-6 states that an IFR GPS with a current database can be used in lieu of ADF or DME.
 
jesse said:
The airplane in question has a Garmin 430 with dual nav/com (with glideslope). NO ADF, NO DME.

Take a look at the following approaches:
http://204.108.4.16/d-tpp/0810/00359IL35.PDF
http://204.108.4.16/d-tpp/0810/00359LBC17.PDF
http://204.108.4.16/d-tpp/0810/00359VDT35.PDF
http://204.108.4.16/d-tpp/0810/00359VT17.PDF

Are any of these approaches possible in the above airplane? If so, which ones, and why. If not, which ones, and why.
Click to expand...

Every one would be legal with a single 430 provided the GPS installation was approved for IFR, a VOR 30 day check was logged and the DB was current. The rules allow an IFR approved GPS to substitute for ADF or DME except for lateral guidance on the final approach course.
 
flyingcheesehead said:
OK, going one at a time, and why I think you picked each one:

1) ILS or LOC RWY 35: Says "ADF or TACAN Required" in the notes due to the IAF and MAHF both being NDB's.

2) LOC BC RWY 17: Says "ADF REQUIRED" in the plan view. IAF and MAHF are both NDB's again (same two, just reversed from the previous approach)

3) VOR/DME or TACAN RWY 35: Says "DME" right in the title of the approach, therefore denoting required equipment. DME arcs, and DME to identify several fixes.

4) VOR or TACAN RWY 17: Says "ADF or DME REQUIRED" on the plan view. You need one or the other to identify FOSRO, the FAF.

I'll take care of 'em all in one swell foop: AIM 1-1-19, Table 1-1-6 states that an IFR GPS with a current database can be used in lieu of ADF or DME.
Click to expand...

Technically you don't have to have a cuffent DB unless the official pilot supplement for the GPS requires it. For the few that don't all you must do is verify the DB information used is current.
 
jesse said:
The airplane in question has a Garmin 430 with dual nav/com (with glideslope). NO ADF, NO DME.

Take a look at the following approaches:
http://204.108.4.16/d-tpp/0810/00359IL35.PDF
http://204.108.4.16/d-tpp/0810/00359LBC17.PDF
http://204.108.4.16/d-tpp/0810/00359VDT35.PDF
http://204.108.4.16/d-tpp/0810/00359VT17.PDF

Are any of these approaches possible in the above airplane? If so, which ones, and why. If not, which ones, and why.
Click to expand...

Since none of these approaches require you to substitute GPS for ADF or DME to provide lateral guidance along the final approach course, you can shoot all of them with your Garmin, assuming it is approved for IFR (properly installed, and in compliance with any limitations in it's manual as far as database currency goes).
 
lancefisher said:
Technically you don't have to have a cuffent DB unless the official pilot supplement for the GPS requires it. For the few that don't all you must do is verify the DB information used is current.
Click to expand...
You must have a current database to use GPS as an ADF/DME sub. See Note 3 to Table 1-1-6 in the AIM. Thus, a current database is required for all of these approaches if you don't have an actual ADF/DME aboard.
 
OOOH, I get to use one of my favorite quotes!

<clearing throat>

"The AIM is not regulatory".

Practically, it makes no difference, but which FAR would you be accused of violating if you used your GPS (with an expired database) in accordance with it's manual which only required you to verify the correctness of the database when operating under IFR?
 
TMetzinger said:
OOOH, I get to use one of my favorite quotes!

<clearing throat>

"The AIM is not regulatory".

Practically, it makes no difference, but which FAR would you be accused of violating if you used your GPS (with an expired database) in accordance with it's manual which only required you to verify the correctness of the database when operating under IFR?
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The AIM may not be regulatory (as in prohibiting), but it can authorize. In this case, your only authority for subbing GPS for ADF/DME comes from the AIM, and it comes limited in this manner. You can press-to-test on this issue if you want, but you'll lose.
 
Ron Levy said:
The AIM may not be regulatory (as in prohibiting), but it can authorize. In this case, your only authority for subbing GPS for ADF/DME comes from the AIM, and it comes limited in this manner.
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Good thought. Isn't there an advisory circular that is the basis for the stuff in the AIM? That would seem to me to be the "authoritative" source.
 
Just to fan the flames a bit here. What if you have no GPS, and an INOP ADF, but have a working DME. Can you still fly the ILS35 legally (first one)?

You can id the TACAN hold fix, but you do not have a tacan.
 
vontresc said:
Just to fan the flames a bit here. What if you have no GPS, and an INOP ADF, but have a working DME. Can you still fly the ILS35 legally (first one)?

You can id the TACAN hold fix, but you do not have a tacan.
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I don't think so. The approach says ADF required and DME is not substitute for ADF (at least I don't think it is). I could also be wrong :)
 
I was thinking more about the secondary Tacan Missed hold wich is on the 114 radial of the STJ vor at 24 DME (HANOT). The plate specifies TACAN, but if I can id HANOT with a VOR/DME can I use it????
 
The chart says "ADF OR TACAN." Thus, if you have neither, you aren't legal to fly the approach, and legally, that's that. As for "why not fly it with VOR and DME?" what you don't know is whether than SJT 114R has been flight-checked for VOR as well as TACAN AZ. It's certainly worth asking the procedures folks, but there's no guarantee that it will work, so it would be a bad idea to try it in the goo until/unless they change that alternate missed approach procedure to "TACAN/DME" and change the big bold print to "ADF OR TACAN OR DME REQUIRED."
 
Not that I was going to try it, I was just wondering why a missed holding fix that you could id using a VOR/DME was restricted to TACAN only.
 
Ron Levy said:
You must have a current database to use GPS as an ADF/DME sub. See Note 3 to Table 1-1-6 in the AIM. Thus, a current database is required for all of these approaches if you don't have an actual ADF/DME aboard.
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According to Bob Sigfried who is the person responsible for pushing the "GPS in lieu of" option through the FAA, there is no requirement for a "Current DB" that cannot be satisfied by verifying either the Lat/Lon for the fix in the DB is correct or by confirming that the associated approach procedure is at least as old as the DB. This is only applicable if the POH supplement for the particular GPS in use doesn't include a more stringent requirement as compliance with the supplement is mandatory. AFaIK the GNS430 family does not allow this but the Apollo GPS-155XL does.
 
lancefisher said:
According to Bob Sigfried who is the person responsible for pushing the "GPS in lieu of" option through the FAA,
Click to expand...
Which FAA office does he work for? AFS-420 or 470 would be the responsible office and I don't see his name listed in 420. I think someone may be confusing the use of GPS as a DME/ADF sub for enroute/terminal versus approach operations. For enroute/terminal, the database need not be current if the points are verified. For subbing on an approach, it is my understanding the database must be current.
 
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I was just with Bob hear at ABS, but saw this post too late to ask him for a reference. This has been a point of confusion for many of us as different authorities have been cited by different folks. Of course, if one keeps a current DB, it's moot--and mine is current <g>

Best,

Dave
 
Ron Levy said:
Which FAA office does he work for? AFS-420 or 470 would be the responsible office and I don't see his name listed in 420. I think someone may be confusing the use of GPS as a DME/ADF sub for enroute/terminal versus approach operations. For enroute/terminal, the database need not be current if the points are verified. For subbing on an approach, it is my understanding the database must be current.
Click to expand...

Bob doesn't work for the FAA, so his word on this is not definitive but I believe he posted something from the FAA confirming his statement. He's away at the ABS convention this weekend, I'll see if I can get more when he returns. I could even be remembering what he posted wrong but I'm very certain that the statement was that WRT to using GPS in lieu of DME or ADF on an approach the requirement for a current (i.e. non-expired) DB only comes from the approved pilot supplement for the particular GPS in question.
 
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Hehe I finally figured out that you guys are talking about the American Bonanze Society, and not about our local ABS in Madison :)
 
lancefisher said:
Bob doesn't work for the FAA, so his word on this is not definitive but I believe he posted something from the FAA confirming his statement.
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When y'all find that definitve something, please let me know. Until then, what he says don't mean jack compared to what's written in the AIM.
 
Ron Levy said:
When y'all find that definitve something, please let me know. Until then, what he says don't mean jack compared to what's written in the AIM.
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Looks like I had it wrong. Here's the reply I got about DB currency requirements when using GPS as as legal substitute for ADF and DME:

Good Evening Lance,

I believe your friend is correct, though there may be an exception under the new language.

If the distance is a portion of a GPS approach, it could be legal, but if the distance in question is one that would normally be found by using a DME, the use is probably illegal.

In the originally published AIM interpretation, the card had to be current for the "In Lieu Of" provisions to be applied. However, if the individual FAA Approved Flight Manual Supplement so stated, an out of date datacard could be used to execute a GPS approach if the data could be determined to be current.


The language concerning using the GPS in Lieu of ADF or DME has been changed and the legality of using the outdated card is now in question.

The current AIM language contradicts the language that is in the new "W" set's FAA Approved Airplane Flight Manual Supplement.

The FAA has stated that we lost no capability via the new language.

Under the old language, the GPS could NOT be used in lieu of an ADF or DME without a current datacard.


1. There is no doubt that the GPS can be used as a substitute for any DME purpose IF the datacard is current.

2. There is no doubt that it could NOT have been used for that purpose with an outdated card under the old language.

The "new" language has muddied the water. The only place that the language actually says that a current datacard is required when the GPS is being used in lieu of a DME is in the tabular listing of approved uses.

However, the new AIM language does make a flat statement that the set must have a current datacard for it to be used to execute a GPS approach. That is in conflict with the language contained in the current production 430W and 530W FAA Approved Flight Manual Supplement unless that individual installation is approved under the local approval process.

I know of none that have been done that way, but anything is possible.

After reading what I just wrote, I am not sure what it says!

Sorry about the lack of a clear and positive reference.

What a mess.

Happy Skies,

Old Bob
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AFS-470 is aware that the change to the AIM in Aug 08 muddied the waters. The problem is that they made that change assuming that the change to the AC on GPS use would be out before the AIM change -- and that didn't happen. When the new AC come out, it will be very clear that the current data card is required.
 
Ron Levy said:
AFS-470 is aware that the change to the AIM in Aug 08 muddied the waters. The problem is that they made that change assuming that the change to the AC on GPS use would be out before the AIM change -- and that didn't happen. When the new AC come out, it will be very clear that the current data card is required.
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Even if they made that change on that assumption, it's still a lousy change in the AIM.

The whole idea of the AIM is to be a reliable practical reference for pilots so that we don't have to search through a bunch of ACs for information that should be at hand.

Having already listed the basics of the requirements for approved GPS for certain operations, I can't imagine the purpose to be served by deleting part of it. Might as well have deleted the whole chapter on the same theory.
 
I agree, Mark -- 100%. But they didn't seem to get that point when I spoke with them on the phone. Consider it another issue on my list when McCain/Obama appoints me FAA Administrator.
 
I'm sure I'll see Old Bob in Tullahoma next week, but in the meantime, can somebody explain this statement to me? The bolded portion is what's confusing me.
However, the new AIM language does make a flat statement that the set must have a current datacard for it to be used to execute a GPS approach. That is in conflict with the language contained in the current production 430W and 530W FAA Approved Flight Manual Supplement unless that individual installation is approved under the local approval process.
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Thanks!

David
 
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