VOR/DME - PROCEDURE NA EXCEPT FOR AIRCRAFT EQUIPPED WITH [GPS]

J

jeremyk13

Pre-Flight
Joined
Jan 15, 2016
Messages
52
Display Name
Display name:
jeremyk13
Ran into this NOTAM while prepping for my IFR checkride...

!FDC 7/5089 SEP IAP STEPHENVILLE CLARK RGNL, Stephenville, TX. VOR/DME-A, AMDT 1A... PROCEDURE NA EXCEPT FOR AIRCRAFT EQUIPPED WITH SUITABLE RNAV SYSTEM WITH GPS, JEN TACAN OUT OF SERVICE. 1704041239-1704111239EST

My understanding of this (translated into more of a conversation) is:

"Sure, you can shoot this approach if you have an IFR GPS. Don't worry that GPS during a VOR approach is only there as a DME substitute or for situational awareness."

Here is the link to the approach chart:

http://155.178.201.160/d-tpp/1704/06026VDA.PDF

Does someone want to correct my understanding? I know that I am capable of shooting the approach using just the GPS, but am I legally allowed to shoot the approach? Assume the plane in question has both a VOR and IFR GPS.
 
The DME (which is part of the TACAN) is not working, so you need a GPS to know your distance to the station and identify the FAF. DME/DME RNAV won't work.

You still MUST use the VOR for course guidance after the FAF.
 
So, the VOR is still in service? TACAN is referring to an individual component of the VORTAC?
 
TACAN is a more accurate version of VOR/DME. The DME portion of the TACAN system is available for civil use; at VORTAC facilities where a VOR is combined with a TACAN, civil aircraft can receive VOR/DME readings.

The DME is down.
 
Aha, nevermind, I see perhaps where @MAKG1 was thinking in that same circular:

USES OF SUITABLE RNAV SYSTEMS NOT ALLOWED BY THIS AC. An otherwise suitable RNAV system cannot be used for the following:

a. NOTAMed Procedures. Unless otherwise specified, navigation on procedures that are identified as not authorized (“NA”) without exception by a NOTAM. For example, an operator may not use a RNAV system to navigate on a procedure affected by an expired or unsatisfactory flight inspection, or a procedure that is based upon a recently decommissioned NAVAID. AC 90-108 3/3/11 Page 6 Par 8

b. Substitution on a Final Approach Segment. Substitution for the NAVAID (for example, a VOR or NDB) providing lateral guidance for the final approach segment.

c. Lateral Navigation on LOC-Based Courses. Lateral navigation on LOC-based courses (including LOC back-course guidance) without reference to raw LOC data.

So DME can be substituted, but you need to use the VOR for the approach.
 
jeremyk13 said:
So, the VOR is still in service? TACAN is referring to an individual component of the VORTAC?
Click to expand...
If the VOR were not in service, the whole procedure would just be NA. There is no way to legally fly the final approach segment without it.
 
jeremyk13 said:
So, the VOR is still in service? TACAN is referring to an individual component of the VORTAC?
Click to expand...
Yes. A TACAN includes the military's version of a VOR. A TACAN operates in a different frequency range from a VOR, and includes DME. "VORTAC" means that there is a VOR and a TACAN at the same location. In that situation, civilian equipment uses the DME that is incorporated in the TACAN. Consequently, when you see "TACAN out of service" at a location that has a VORTAC, you cannot use the DME, but the VOR is unaffected.

(If a VOR that is not co-located with a TACAN has DME, that is referred to in the A/FD as a VOR/DME.)

[Edit: I guess I type too slowly!)
 
Last edited:
Ask your instructor if you could fly this if the VOR OR DME went down :

upload_2017-4-4_11-56-50.png
 
citizen5000 said:
TACAN is a more accurate version of VOR/DME. The DME portion of the TACAN system is available for civil use; at VORTAC facilities where a VOR is combined with a TACAN, civil aircraft can receive VOR/DME readings.

The DME is down.
Click to expand...

First time I've heard that TACAN is more accurate than VOR. I have no experience with it.

I recall when the military was trying to decide whether to go with VOR in the 1950s, or so. The Navy said VOR wouldn't work on a ship, but TACAN would. Seems like the Navy/Marines were the big adapters of TACAN. Not so much the USAF or Army.
 
Palmpilot said:
Yes. A TACAN includes the military's version of a VOR. A TACAN operates in a different frequency range from a VOR, and includes DME. "VORTAC" means that there is a VOR and a TACAN at the same location. In that situation, civilian equipment uses the DME that is incorporated in the TACAN. Consequently, when you see "TACAN out of service" at a location that has a VORTAC, you cannot use the DME, but the VOR is unaffected.

(If a VOR that is not co-located with a TACAN has DME, that is referred to in the A/FD as a VOR/DME.)

[Edit: I guess I type too slowly!)
Click to expand...
Sometimes you will see a TACAN Azimuth out of service Notam
 
aterpster said:
First time I've heard that TACAN is more accurate than VOR. I have no experience with it.

I recall when the military was trying to decide whether to go with VOR in the 1950s, or so. The Navy said VOR wouldn't work on a ship, but TACAN would. Seems like the Navy/Marines were the big adapters of TACAN. Not so much the USAF or Army.
Click to expand...
I've never heard that either, that it's more accurate. Wouldn't surprise me though. Another thing about TACAN just for trivia's sake is they have a wider "cone of silence" than VOR. You will never see a holding pattern over a TACAN.
 
You must log in or register to reply here.
Back
Top