What do solid blue lines indicate on a sectional chart?

Solid blue lines on a sectional chart indicate the boundaries of Class B airspace. Class B airspace is typically associated with the busiest airports in the United States, where there are significant levels of air traffic, and is designed to protect both commercial and general aviation aircraft.

Class B airspace is depicted with a solid blue outline, distinguishing it from other classifications of airspace. This airspace typically extends from the surface up to a designated altitude and is designed to manage the flow of air traffic in the vicinity of major airports, ensuring safety and efficiency.

To safely operate in Class B airspace, pilots must obtain clearance from Air Traffic Control (ATC) before entering. Understanding the visual cues on sectional charts, such as solid blue lines, is crucial for pilots to navigate safely and comply with aviation regulations.