What configuration of sectional lines typically represents Class D airspace?

Class D airspace is typically represented on sectional charts using dashed blue lines. This specific configuration indicates the boundaries of the airspace, which generally surrounds airports with an operational control tower that do not have the higher thresholds of airspace classification seen in Class B areas. The use of dashed lines helps to visually denote that it is a lower level of controlled airspace, which allows for more flexibility compared to stricter classifications.

The choice of dashed lines rather than solid lines plays an important role in understanding sectional charts, as solid lines are often used to represent more restrictive airspace types, such as Class B airspace, which requires more stringent communication and clearance procedures. Thus, dashed blue lines serve as a clear and recognizable indicator for pilots navigating through or near Class D airspace, guiding them to follow established protocols for operations within this environment.