Which identifier is used for IFR Military Training Routes?

The identifier "IR" is specifically designated for IFR (Instrument Flight Rules) Military Training Routes. These routes are planned by the military for training purposes and allow military aircraft to operate under IFR conditions while interacting with civilian airspace. The use of "IR" helps air traffic control and other pilots to easily identify and manage traffic associated with these military operations, ensuring safety and coordination in the airspace.

In contrast, "VR" identifiers are used for VFR (Visual Flight Rules) Military Training Routes. These are intended for training at lower altitudes and generally involve visual navigation. The other identifiers, such as "AT" and "TR," do not correspond to military training route designations. Thus, the correct identification for IFR military training routes is "IR."