Definition
A Military Training Route (MTR) flown under Instrument Flight Rules, used by military aircraft to practice low-altitude, high-speed tactical flight. IR routes are operated regardless of weather conditions and may include segments above 1,500 feet AGL. They are charted on VFR sectionals and IFR low-altitude en route charts as lines labelled with the prefix 'IR' followed by a route number (for example, IR-104).
Plain English
An IR is a military training route where aircraft fly fast and low under instrument rules. Civilian pilots need to know where these routes are because military jets can appear there at any time, in any weather.
Context Anchor
Seen on aviation charts and in airspace discussions for military training routes, usually as IR followed by a route number.
Derivation
The 'I' stands for IFR (Instrument Flight Rules) and the 'R' stands for Route. The prefix distinguishes IR routes from VR routes, which are flown under Visual Flight Rules.
Why Pilots Care
Active IR routes can contain fast-moving military traffic that may not see or avoid civilian aircraft.
Grounding Statement
An IR is a charted route, not a block of airspace that is automatically closed to other pilots.
Intuition Check
IR does not mean Instrument Rating in this context. On airspace charts, IR means an IFR military training route.
Example Sentence 1
While planning the cross-country, the student noticed an IR route crossing the proposed track and made a note to listen for military traffic in that area.
Example Sentence 2
IR routes are flown under instrument rules and marked differently from VR routes on aeronautical charts.