an improvement to a subsonic passenger aircraft is provided . the passenger aircraft has a fuselage including a main passenger seating deck including forward , middle , and aft regions . the fuselage includes an upper forward deck located above the main passenger seating deck forward region and accessible thereto . both the main deck and upper forward deck having doors , therein for passenger and supplies ingress and egress . the fuselage includes an aft upper deck located above the main passenger seating deck aft region and accessible from the main deck . an upper middle region is located above the main deck middle region . in one embodiment , the upper middle region is of a height elevationally less than either of the forward and aft upper decks . the cross - sectional area of the fuselage at the upper middle region is less than the cross - sectional area of the fuselage at either the forward upper deck region or the aft upper deck region . in another embodiment , the forward upper cabin and the aft upper cabin are separate , longitudinally non - adjacent cabins for accommodating seated passengers .