Plain English Meaning

It is a curved section of a flight path shaped like part of a circle. The aircraft flies around a fixed point at a fixed distance, so the turn follows the same exact curve every time.

Full Definition

An RF (Radius-to-Fix) leg is an RNAV path segment defined as a constant-radius circular arc between two fixes, curving around a defined center point. The leg is fully specified by its terminating fix, the center of the arc, and the radius, allowing the aircraft to fly a precise, repeatable curved ground track. RF legs require aircraft and avionics specifically authorized for RF capability and are commonly used in RNP approach and departure procedures where terrain, , or demand a tightly curved path.