In a commercial aircraft with a main deck (2) and a lower deck (5, 6), at least one passenger cabin (16, 16′) is also provided on the lower deck. The fuselage diameter lies on the order of a wide-body aircraft, and an energy-absorbing deformation structure (22, 23, 24) is arranged underneath the lower deck cabin. The invention proposes to arrange the wings (7) on the aircraft fuselage in accordance with the shoulder wing configuration, and to arrange the landing gear (10) outside on the fuselage such that the landing gear bays are spaced apart from one another by a certain distance that is defined by the positioning of the bottom longeron spars (9). This may provide that the lower deck volume situated underneath the main deck can be optimally utilized for payloads. The lower deck areas may also be interconnected in such a way that a significant useful width of the passage between the landing gear bays is achieved.