Which of the following is NOT one of the four types of low-level air routes?

The classification of low-level air routes is designed to manage various navigation requirements and ensure safe operations for aircraft flying at lower altitudes. The four recognized types include VHF/UHF air routes, LF/MF air routes, and L Routes.

VHF/UHF air routes utilize very high frequency and ultra high frequency bands for communication and navigation, while LF/MF air routes employ low frequency and medium frequency radio waves. L Routes are specifically designated navigational routes that facilitate air traffic operations at lower altitudes, often used for routing between airports or along specific corridors.

Mixed-mode air routes are not categorized as one of the standard types of low-level air routes. While the terminology might suggest a combination of various air route types, it does not align with the established classification scheme used in aviation. Thus, it stands apart from the commonly accepted terminology for low-level air routes.