What unit is used for all mileages in IFR planning and operations?

In IFR (Instrument Flight Rules) planning and operations, nautical miles (NM) are used as the standard unit for all mileages. This choice is correct because nautical miles are specifically designed for navigation and aviation purposes, as they are based on the circumference of the Earth. One nautical mile is equivalent to one minute of latitude, which allows for more accurate positioning when flying over long distances compared to other units of measure.

While meters, statute miles, and kilometers are commonly used in various contexts, they do not provide the same level of consistency and relevancy to aviation navigation that nautical miles do. Nautical miles are integral to the global air traffic control system, ensuring that all aircraft follow the same navigation standards, which is essential for safe and efficient operations in controlled airspace.