In aviation, how is distance primarily expressed?

In aviation, distance is primarily expressed in nautical miles because this measurement is directly related to the Earth's geometry. A nautical mile is defined as one minute of latitude, which is essential for navigation. Since the Earth is roughly spherical, using nautical miles allows pilots and navigators to maintain a consistent reference when plotting courses on charts that represent the curvature of the Earth.

Additionally, because nautical miles correlate with degrees of latitude, they are particularly useful in aviation where flight paths often involve changes in latitude and longitude. Unlike statute miles, which are more commonly used in terrestrial contexts, the nautical mile is a standard unit of measurement in both maritime and aviation navigation, ensuring that pilots have a common frame of reference when estimating distances and planning flights.

The other measurement units, while useful in specific contexts (such as statute miles for driving distances on land or feet and yards for height and distances in other sports), are not applicable for the overarching navigation needs in aviation, where precise and universally understood distance calculations are crucial for safety and operational efficiency.