A blue vignette on an aeronautical chart indicates which class of airspace?

The blue vignette on an aeronautical chart specifically indicates Class E airspace. This type of airspace is generally used to provide controlled airspace for operations, particularly in the vicinity of airports, where terminal activities are prevalent or to manage the transition between different classes of airspace.

Class E airspace has specific altitudes and boundaries that can vary but typically starts at the surface in certain areas or at a designated altitude above the surface and extends up to, but not including, 18,000 feet MSL (Mean Sea Level). The blue vignette helps pilots visually interpret where this controlled airspace begins and ends on charts, ensuring they are aware of the regulations and operational requirements applicable within this airspace.

The other types of airspace represented on aeronautical charts do not use the blue vignette symbol. Class G airspace, for example, is designated typically with no vignette, indicating uncontrolled airspace. Class A airspace is not depicted with a blue vignette either, as it has a specific altitude requirement starting at 18,000 feet, and prohibited areas are marked using different symbols altogether. Thus, understanding these visual indications is crucial for pilots to navigate safely and comply with airspace regulations.