Plain English Meaning

A standard route between two airports that ATC would like you to fly. Filing it makes your clearance smoother because it matches what controllers are already planning to give you.

Full Definition

A published route between two airports that ATC prefers IFR flights to use, established to streamline traffic flow into, out of, and between busy terminal areas and to reduce controller workload. Preferred IFR routes are listed in the Chart Supplement and are typically expected to be filed in flight plans when applicable.

Context Anchor

Seen when planning or filing an IFR flight plan, reviewing published IFR route guidance, or receiving an that follows established - routing.