Definition
Published IFR routes between busy terminal areas, established by the FAA to standardize traffic flow, reduce controller workload, and minimize routing changes. They are listed in the Chart Supplement and are designed to be used between specific city pairs or fix pairs, with separate routes often published for low and high altitudes.
Plain English
These are pre-set IFR routes the FAA wants pilots to file when flying between certain busy areas. Filing one of these routes makes it more likely your flight plan will be accepted as filed, without ATC rerouting you.
Context Anchor
You may see Preferred IFR Routes when planning or filing an instrument flight plan, especially between busy airports or through congested airspace.
Derivation
“Preferred” comes from the idea of choosing one option ahead of others. In this term, it means the FAA’s preferred routing for traffic flow, not simply the route a pilot personally likes best. “IFR” means Instrument Flight Rules, the rules used when a flight is planned and controlled by reference to instruments and air traffic control clearances.
Why Pilots Care
Filing a Preferred IFR Route often results in faster clearance approval and fewer route amendments from ATC.
Intuition Check
“Preferred” does not mean the pilot’s favorite route. Here it means the route air traffic control normally wants aircraft to use for orderly traffic flow.
Example Sentence 1
Before filing IFR from Boston to New York, she checked the Chart Supplement for the Preferred IFR Route to avoid getting a full reroute at clearance delivery.
Example Sentence 2
Using the Preferred IFR Route between Chicago and New York allowed the controller to issue a clearance without delay.