Preferred IFR routes

Definition of “Preferred IFR Routes”

“Preferred IFR routes” refers to established flight paths within major terminal and en-route environments that are designed to enhance the efficiency and capacity of the air traffic control system. Pilots receive instrument flight rules (IFR) clearances based on these prescribed routes, which are listed in the Chart Supplement U.S. unless severe weather avoidance procedures or other factors dictate otherwise. These routes are continually monitored and updated by aviation authorities to ensure the safe and reliable movement of air traffic.