Definition
Military Training Routes are airspace corridors established jointly by the FAA and the Department of Defense to allow military aircraft to conduct low-altitude, high-speed training, generally below 10,000 feet MSL and often at speeds in excess of 250 knots. MTRs are identified on aeronautical charts and are designated as either IR (IFR routes) or VR (VFR routes), with a route number indicating whether any segment exceeds 1,500 feet AGL: three-digit numbers (e.g., IR123, VR456) indicate the route includes segments above 1,500 feet AGL, while four-digit numbers (e.g., IR1234, VR4567) indicate the route is flown entirely at or below 1,500 feet AGL.
Plain English
MTRs are marked corridors on aviation charts where military aircraft fly fast and low for training. Civilian pilots can fly through them, but should expect to share the airspace with military jets moving very quickly close to the ground.
Context Anchor
Seen on aeronautical charts and during preflight route planning, especially when a planned flight crosses or follows near a military training route.
Derivation
Military comes from the Latin word for soldier. Route comes through French from the idea of a road or path. Together, Military Training Routes means planned paths in the sky used by military aircraft for practice.
Why Pilots Care
VFR pilots must remain especially alert near these routes because military jets may operate at high speeds and low altitudes with limited time to see and avoid other traffic.
Intuition Check
Do not assume an MTR means the airspace is closed to civil aircraft. It means military aircraft may be using a published path, often fast and low, so extra planning and scanning are needed.
Example Sentence 1
During preflight planning, she noticed her route crossed VR1644 and called Flight Service to check whether the MTR was scheduled to be active that afternoon.
Example Sentence 2
The instructor noted that traffic on MTRs can fly as low as 500 feet AGL at speeds exceeding 400 knots.