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Above Victor airway 154 on the IFR enroute low altitude chart, there is a grey zigzag line between Dublin VORTAC and LOTTS intersection.

What does the gray zigzag over the segment indicate?

V154 between DBN and LOTTS

Credit: SkyVector

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According to the “Airspace Information” section of FAA Aeronautical Chart User’s Guide, it is a low-altitude unusable route. The high-altitude flavor is similar in shape with a smaller amplitude.

See also page 62 of the Guide PDF, if you prefer.

UNUSABLE ROUTE Low- and high-altitude unusable routes

In this particular case, observe the overprint on 110 in the compass rose surrounding DBN, which indicates abnormal status. The Airport/Facility Directory entry for Dublin VORTAC (as of the 31 MAR 2016 publication) reads, with added emphasis:

DUBLIN N32°33.81′ W82°49.80′ NOTAM FILE MCN.
  (L) VORTAC 113.1 DBN Chan 78 276º 7.9 NM to W H 'Bud' Barron. 306/5W. HIWAS.
    VOR portion unusable:
      215°–285° byd 10 NM blo 3,500’
      001°–139° byd 33 NM
      001°–139° blo 5,000’
RCO 122.1R 122.6 113.1T (MACON RADIO)

Note that the DBN 110 radial falls within the 001-139° unusable range. Beyond LOTTS intersection, V154 is defined with reference to the Savannah VORTAC.

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  • 1
    $\begingroup$ What might make the route unusable? Why would it be marked out rather than removed? $\endgroup$ – fooot May 18 '16 at 17:04
  • $\begingroup$ Why does the route exist if its unusable? What is it that makes it unusable? $\endgroup$ – abelenky May 18 '16 at 17:12
  • $\begingroup$ My guess as to why it's still there is to make it obvious to someone who might be familiar with the area from the past that the route did exist in the past but now should not be used. $\endgroup$ – Simon May 18 '16 at 18:08
  • $\begingroup$ Is there a relation between the loss of reception and the two different radii of the VORTAC rose? $\endgroup$ – mins May 18 '16 at 18:47
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    $\begingroup$ It would appear, according to this that they deleted that segment and raised the MEA for the LOTTS-SAV segment to 3000 ft due to towers built within the airway borders. Magic 98.1 has a tower 1.5 nm N of OCONE. And there's a cell tower 4.6nm NE of LOTTS $\endgroup$ – TomMcW May 18 '16 at 20:52

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