Which type of airspace is described as having blue circles on a chart?

The type of airspace indicated by blue circles on a chart is Class B airspace. This class of airspace is typically found around major airports and is designed to manage high-density air traffic. The boundaries of Class B airspace are depicted on navigational charts with solid blue lines and the airspace appears as a series of concentric circles.

Class B airspace extends from the surface to a specified altitude, and entry into this airspace requires pilots to obtain air traffic control clearance. This is important for maintaining safe distances between aircraft and managing the flow of traffic around busy airports. Understanding the visual representation of different airspace classifications is crucial for pilots to navigate safely and comply with regulatory requirements, especially in congested areas.

The distinction in color and design on charts helps pilots quickly identify airspace types, which is critical for planning and executing safe flight operations.