A fixed wing of an aircraft, having a main wing extending over a half-span with a wing box including spars extending along the spanwise direction of the main wing, ribs arranged one in back of the other viewed in the spanwise direction, and an outer skin. The wing box includes a wing box base section (K10) and a wing box adapter section, that forms the outer end area of the wing box, as viewed from the wing root, and is designed to secure a wing tip device. In its nominal state of construction, the dihedral angle of the wing box adapter section referring to the respective local spanwise direction continuously increases by at most 60 degrees from the outer rib of the wing box base section (K10) up to the outermost rib of the wing box adapter section.