Section 3. Low/Medium Frequency and VOR
20-3-1. NAVAID SPACING
a. VOR Federal airways are based on NAVAIDs which
normally are spaced no farther apart than 80 NM. They may be
based on more widely spaced NAVAIDs if a usable signal can
be provided and frequency protection afforded for the
distance required (see Order 9840.1, U.S. National Aviation
Handbook for the VOR/DME/TACAN Systems).
b. NAVAID spacing for L/MF airways has no standard but
is determined on an individual basis.
20-3-2. VERTICAL AND LATERAL EXTENT
standard vertical and lateral extent of these airways is
specified in FAAO 8260.3, TERPS, and FAAO 8260.19, Flight
Procedure and Airspace. Nonstandard dimensions may be
specified as required except as limited by any flight
inspection limitations and by paragraph
20-1-7 of this
20-3-3. WIDTH REDUCTIONS
a. Width reductions are not applicable to L/MF airways.
b. For ATS routes other than L/MF, a reduced airway
width of 3 NM on one or both sides of the centerline may be
established from the NAVAID to the point where 4.5 degree
intersecting lines equal 3 NM. Normally, lines perpendicular
to the airway centerline determine the ends of the reduced
portion. If required, the ends of the reduced portion may be
defined differently. A reduced width is permissible to
obtain additional traffic capacity and flexibility through
the use of multiple routes and to avoid encroachment on
special use airspace or other essential maneuvering areas.
Width reductions are considered the exception rather than
the rule and are approved only where adequate air navigation
guidance and justification exist.