What color is used on aeronautical charts to depict airports with control towers in Class B, C, D, and E airspace?

The color used on aeronautical charts to depict airports with control towers in Class B, C, D, and E airspace is blue. This color is specifically chosen to provide clarity and to ensure that pilots can easily identify controlled airports at a glance.

In aeronautical chart symbology, blue indicates airports that have established air traffic control services, allowing pilots to understand quickly where they can expect organized traffic management and additional navigational support. This is particularly important for navigating in more complex airspace like Class B, C, D, and E, where controlled flight operations are common.

The use of blue for these airports helps differentiate them from uncontrolled airports and enhances safety by providing a clear visual reference for pilots during flight operations. Understanding these color codes is essential for effective navigation and situational awareness in aviation.