What designation is used to identify high-level fixed RNAV routes?

High-level fixed RNAV (Area Navigation) routes are designated as Q-Routes. These routes are specifically established for aircraft operating in the high-altitude en-route airspace and are designed to optimize the efficiency of air traffic by allowing more direct routing and improved management of airspace. Q-Routes provide a structured network of airways that can be utilized by RNAV-equipped aircraft, enabling them to follow precise flight paths in a more flexible manner compared to traditional navigation routes.

The designation system uses letters to categorize these routes according to their altitude and use case, with Q-Routes being specifically for high altitude, whereas other categories such as A-Routes, J-Routes, and T-Routes pertain to different altitudes or purposes. A-Routes are typically used for traditional airways, J-Routes are set for jet routes, and T-Routes are associated with terminal airspace operations. In this context, choosing Q-Routes accurately identifies the specific type of RNAV routing at high altitudes.