What do the letters "C" and "R" stand for on a sectional chart?

The letters "C" and "R" on a sectional chart signify "Controlled" and "Restricted," respectively. Controlled airspace represents regions where air traffic control (ATC) has authority over aircraft operations to ensure safety and avoid conflicts between different aircraft. This type of airspace is established around airports or flight corridors to manage all types of air traffic, allowing for the safe integration of commercial and general aviation operations.

Restricted airspace is designated to protect certain areas where flight operations are prohibited or limited, usually for reasons related to national security or safety. This could include military training routes, test flight areas, or other sensitive locations where only authorized personnel are allowed to operate within that airspace.

Understanding these designations is crucial for pilots as they navigate and plan their flights, to ensure compliance with regulations and to maintain safety in the national airspace system.