Plain English Meaning

IR206 is the name of one specific military low-altitude training route. The 'IR' part means the route is flown under instrument flight rules, and the number tells you which route it is.

Full Definition

An example designator for a specific Military Training Route (MTR) flown under Instrument Flight Rules (IFR). The 'IR' prefix identifies the route as IFR, and the route number that follows it (in this case 206) is the unique identifier for that particular route. A three- or four-digit number indicates the route is generally flown at or below 1,500 feet AGL.

Context Anchor

Seen on aeronautical charts and in route information for Military Training Routes.

Derivation

IR' stands for 'IFR Route.' The number is simply an identifier assigned by the military and FAA. Three- or four-digit numbers were chosen to indicate routes flown at or below 1,500 feet AGL, while one- or two-digit numbers indicate routes that include segments above 1,500 feet AGL.