Width of a DME arc

[AC560]

I got a little booklet the other day from IFR Refresher called On The Approach that talked about various things. One of the things of interest was they were discussing a DME arc and the writer stated that a DME arc has the same width as an airway. I had never heard that before (seems to make sense though) and have been poking around trying something to validate the writers statement.

Anyone able to point me in the right direction?

 

[nosehair]

TERPs. Just pointing you, not taking you there. You will find all about how approaches are designed.

 

[AC560]

Thanks found it.

 

[The_Russian]

Linky? I would like to learn more about this.

 

[VNugget]

Instrument Procedures Handbook page 5-36

 

[AC560]

Instrument Procedures Handbook page 5-36

5-38 and it cites the tolerance slightly different then TERPS but they match up. They have a nice picture on 5-39.

Instrument Procedures Handbook 5-38
Required obstruction clearance (ROC) along the arc
depends on the approach segment. For an initial
approach segment, a ROC of 1,000 feet is required in
the primary area, which extends to 4 NM on either side
of the arc. For an intermediate segment primary area
the ROC is 500 feet. The initial and intermediate segment
secondary areas extend 2 NM from the primary
boundary area edge. The ROC starts at the primary
area boundary edge at 500 feet and tapers to zero feet at
the secondary area outer edge.

8260.3BCHG19
(2) Width. The total width of an arc
intermediate segment is 6 miles on each side of the arc.
For obstacle clearance purposes, this width is divided
into a primary and a secondary area. The primary area
extends 4 miles laterally on each side of the arc
segment. The secondary areas extend 2 miles laterally
on each side of the primary area (see figure 10).

 

[Say Again Over]

Thanks for posting.

 

[Metro752]

6 miles, if u maintain ur alt, which is rediculous