Military Training Routes (MTRs) with no segment above 1,500' AGL shall be identified by four number characters (IR1206/VR1207)

MTRs that include one or more segments above 1,500' AGL shall be identified with three number characters (IR206/VR207).

What is the meaning of segment in MTRs?

What is the difference between three and four?


1 Answer 1


A route is how you go from place to place. A segment is a portion of your route which is characterized by a consistent course/altitude.

A route may have one segment, or many. An MTR is a Military Training Route. If no portions of the route exceed 1,500 AGL, then it is given a four-digit identifier.

I'm pretty sure that the three-digit / four-digit decision was arbitrary, but I'm ready to be educated.

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