By definition, a feeder route is a route depicted on IAP
charts to designate courses for aircraft to proceed from
the en route structure to the IAF. Feeder routes, also
referred to as approach transitions, technically are not
considered approach segments but are an integral part of
many IAPs. Although an approach procedure may have
several feeder routes, pilots normally choose the one
closest to the en route arrival point. When the IAF is part
of the en route structure, there may be no need to designate
additional routes for aircraft to proceed to the IAF.
When a feeder route is designated, the chart provides
the course or bearing to be flown, the distance, and the
minimum altitude. En route airway obstacle clearance
criteria apply to feeder routes, providing 1,000 feet of
obstacle clearance (2,000 feet in mountainous areas).
Figure 5-27. Approach Segments and Obstacle Clearance.