Definition
A Military Training Route is a defined corridor of airspace established jointly by the FAA and the Department of Defense for military aircraft to conduct low-altitude, high-speed training, often above 250 knots. MTRs are identified on charts by an IR (instrument route) or VR (visual route) prefix followed by a number, and they may extend from the surface up through several thousand feet.
Plain English
It is a charted flight path used by military aircraft to practice flying fast and low. Civilian pilots need to know where these routes are so they can stay clear or stay alert when crossing them.
Context Anchor
You will see MTRs during preflight planning on aeronautical charts, especially when planning a route through areas used for military training.
Why Pilots Care
Civilian pilots must locate and avoid active MTRs to prevent conflicts with fast, low-flying military traffic.
Intuition Check
Do not assume an MTR is closed airspace. It is usually a warning that military training traffic may be present, not a blanket prohibition on civilian flight.
Example Sentence 1
During flight planning, she noticed her route crossed an MTR and called Flight Service to check whether it was active that morning.
Example Sentence 2
The briefing warned that an active MTR could have high-speed military traffic at low altitude.