GPS substitute for NDB

dmspilot

dmspilot

Final Approach
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I understand that GPS can be substituted in many cases, but it cannot be substituted in the case of an "NDB approach."

What about a "VOR/NDB" or "LOC/NDB" approach? Do I *have* to have and use ADF since NDB is in the name of the approach, even though it's not the primary navaid?
 
No you do not have to have ADF in those cases. Assuming you are still meeting all the requirements and limitations associated with GPS substitution.

Effective July 16, 1998, pilots may substitute IFR-certified GPS receivers for DME and ADF avionics for all operations except NDB approaches without a GPS overlay. GPS can be used in lieu of DME and ADF on all localizer-type approaches as well as VOR/DME approaches, including when charted NDB or DME transmitters are temporarily out of service. It also clarifies that IFR GPS satisfies the requirement for DME at and above Flight Level 240 specified in FAR 91.205(e). This approval represents a major step toward removing the need to retain DME or ADF in our cockpits for any reason.
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Charted requirements for ADF and/or DME can be met using the GPS system, except for use as the principal instrument approach navigation source.
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Which in the cases you mentioned would be the VOR or LOC. Basically the GPS can't be substituted for the lateral guidance on the final approach segment.
 
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dmspilot said:
What about a "VOR/NDB" or "LOC/NDB" approach? Do I *have* to have and use ADF since NDB is in the name of the approach, even though it's not the primary navaid?
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If you go into AIM Section 1-2-3, you'll see that the question is whether or not the NDB is being used for lateral guidance on the final segment. If it is, then you can't substitute GPS, but if not, you can. However, I've never seen a VOR/NDB or LOC/NDB approach, so I can't say what such an approach would be using the NDB to accomplish. Perhaps if you post an example, I could give a better answer.
 
dmspilot said:
I understand that GPS can be substituted in many cases, but it cannot be substituted in the case of an "NDB approach."

What about a "VOR/NDB" or "LOC/NDB" approach? Do I *have* to have and use ADF since NDB is in the name of the approach, even though it's not the primary navaid?
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Could you cite an example of a "VOR/NDB" or a "LOC/NDB" approach?
 
Ron Levy said:
If you go into AIM Section 1-2-3, you'll see that the question is whether or not the NDB is being used for lateral guidance on the final segment. If it is, then you can't substitute GPS, but if not, you can. However, I've never seen a VOR/NDB or LOC/NDB approach, so I can't say what such an approach would be using the NDB to accomplish. Perhaps if you post an example, I could give a better answer.
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Ah, thanks for pointing me to the correct AIM section.

Here is an example of a LOC/NDB approach. An NDB is used to identify the FAF.
http://155.178.201.160/d-tpp/1502/05664LN5.PDF
 
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Palmpilot said:
Since that link will expire, I'm posting a note for future reference that it is for the LOC/NDB RWY 1 approach at Fitzgerald Muni (FZG) in Georgia.
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I believe it is incorrectly named.

It should be LOC in the title with a plan view note ADF REQUIRED.
 
dmspilot said:
Ah, thanks for pointing me to the correct AIM section.

Here is an example of a LOC/NDB approach. An NDB is used to identify the FAF.
http://155.178.201.160/d-tpp/1502/05664LN5.PDF
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Since the NDB is used on that approach only to identify a fix, and not for lateral guidance on the final segment, an IFR GPS is a legal substitute for ADF on that approach.


And thanks for digging that one out -- I'd never come across a LOC/NDB approach before. However, I'm not going to dispute Wally who knows TERPS better than any other three people alive put together as to whether or not these two approaches are incorrectly named.
 
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Ron Levy said:
Since the NDB is used on that approach only to identify a fix, and not for lateral guidance on the final segment, an IFR GPS is a legal substitute for ADF on that approach.


And thanks for digging that one out -- I'd never come across a LOC/NDB approach before. However, I'm not going to dispute Wally who knows TERPS better than any other three people alive put together as to whether or not these two approaches are incorrectly named.
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I never saw one of those - suspect it'll be gone soon, anyway.

---

As an aside, I wish some rich and foolish person would commission a 4-course A-N range, just for fun. :D
 
aterpster said:
John,

so far as I know, such beasts are common in some other countries, but rare in the U.S.
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Nav Canada, CAP 3;
I've noticed that in Canada on ILS and LOC(BC) approach charts if there's an NDB defining the nonprecision FAF the chart is labeled "ILS or NDB RWY **" or "LOC(BC) or NDB RWY **", unlike in the US they don't publish a separate chart for the NDB approach they just add "NDB" minima. Is this what you're referring to? In any case I'd interpret that as an "or" and not an "and".
 
Gucci Pilot said:
How so?
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Because the NDB isn't used for course guidance on the final approach segment is my guess.

Because it's only used for identifying the FAF and for the MAP, IFR GPS is an acceptable substitute.

I would agree with aterpster.
 
Turningfinal said:
Because the NDB isn't used for course guidance on the final approach segment is my guess.

Because it's only used for identifying the FAF and for the MAP, IFR GPS is an acceptable substitute.

I would agree with aterpster.
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In that case, along with screwing up the name at KFZG, they also screwed it up at KHIE, KCZL, KCTJ, and 2G9.
 
Ron Levy said:
Since the NDB is used on that approach only to identify a fix, and not for lateral guidance on the final segment, an IFR GPS is a legal substitute for ADF on that approach.


And thanks for digging that one out -- I'd never come across a LOC/NDB approach before. However, I'm not going to dispute Wally who knows TERPS better than any other three people alive put together as to whether or not these two approaches are incorrectly named.
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It's been passed on to the true experts. There is a disagreement as to the naming. But, even the defender says with Change 26 to TERPs, when next revised it will be simply LOC with "DME Required" either in the plan view or briefing strip.
 
Wow, you not only submitted an inquiry, but also got multiple answers with a debate, all in a matter of a few hours?
 
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