Plain English Meaning

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.

Full 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 ( routes), with a number indicating whether any exceeds 1,500 feet : 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.