Definition
IR routes are military training routes flown under instrument flight rules, used by military aircraft to practice low-altitude, high-speed navigation and tactical flying. They are charted corridors where military aircraft may operate at speeds in excess of 250 knots below 10,000 feet MSL, with their flights conducted under IFR procedures regardless of weather conditions.
Plain English
IR routes are special low-level flight paths set aside for military jets to train on. The military aircraft fly these routes using their instruments to navigate, often fast and low, in any weather.
Context Anchor
Seen on aeronautical charts and in route planning, usually as an IR label with a route number, such as IR-123.
Derivation
The letters come from IFR route. IFR means instrument flight rules, and the R points to the published route used for the training flight.
Why Pilots Care
VFR pilots must identify these routes to avoid conflicts with high-speed military traffic operating under IFR.
Grounding Statement
If your planned course crosses an IR route, picture a military training path that may have fast traffic moving along it.
Intuition Check
IR does not mean instrument rating or infrared in this context. Here, IR means an IFR military training route.
Example Sentence 1
During preflight planning, the pilot noticed her cross-country route crossed IR-107 and called Flight Service to check whether the route was active.
Example Sentence 2
ATC issued a clearance for the military flight to proceed along IR-312 under instrument rules.