What is indicated by a Military Training Route designated with a number 4?

A Military Training Route designated with a number 4 indicates that it is a low-altitude route. Specifically, these routes are designed for military aircraft to conduct training operations at altitudes below 1,500 feet above ground level (AGL). These low-altitude training routes allow military pilots to practice maneuvers and operations in close proximity to the ground, which is crucial for tactical training.

Understanding the designation system helps pilots and other airspace users recognize the operational environment and the potential for military activity in the area. While higher-numbered training routes (like those designated with a number 5 or above) may involve higher altitudes or specific security protocols, a route labeled with a 4 specifically denotes the low-altitude nature of the training being conducted.