Airplane with multi-level cabins for cargos or passengers and method of loading cargos into same

An aircraft with multi-level cabins functioning as a cargo cabin or passenger cabin, comprising a first cabin (411) provided with a cargo hatchway (423) which is opened and closed by a cargo door (412) on a fuselage (400) and a second cabin (421) which is used as a passenger cabin and is positioned above or under said first cabin (411), wherein a galley service space (419) is provided in said second cabin (421). An elevator is provided for conveying a cargo item, moved into said first cabin (411) through said cargo hatchway (423), to said second cabin (421), and for conveying back said conveyed cargo item from said second cabin (421) to said first cabin (411), thereby said cargo item is moved between the exterior of said aircraft and said second cabin (421). Said elevator is arranged to convey a wagon container (401) which can load a plurality of wagons (413) between said galley service space (419) and said first cabin (411) for moving said wagons (413) in and out from said galley service space (419) and for conveying said wagon container (401) with the wagons (413) loaded therein between the exterior of said aircraft and said galley service space (419).