the present invention relates to apparatus and methods for providing more efficient use of lavatory space . many specific details of certain embodiments of the invention are set forth in the following description and in fig1 - 6 to provide a thorough understanding of such embodiments . one skilled in the art , however , will understand that the present invention may have additional embodiments , or that the present invention may be practiced without several of the details described in the following description . fig1 illustrates a view of a lavatory unit 20 formed in accordance with an embodiment of the invention . this embodiment may be used in any aircraft , other vehicles ( e . g ., ships , buses , trains , subways , monorails , etc . ), or as a stand - alone unit . the lavatory unit 20 may include a commode 26 , and a sink 28 . the lavatory unit 20 includes an amenities cabinet 30 having an opening 32 at an exterior wall 34 of the lavatory unit 20 . the amenities cabinet 30 slideably receives an amenities module 40 through the opening 32 . in this embodiment , the amenities module 40 includes sliding brackets 50 or similar devices for allowing the amenities module 40 to be slideably received by corresponding tracks or rolling devices ( not shown ) within the amenities cabinet 30 . the amenities module 40 includes an external panel 60 having a locking dial 64 that when turned into a locking position , locks the amenities module 40 within the amenities cabinet 30 . the external panel 60 matches the exterior wall 34 and is flush with the exterior wall 34 when the amenities module 40 is fully received within the amenities cabinet 30 . in one particular embodiment , the amenities module 40 includes various compartments for storing amenities , such as without limitation tissues , paper towels , soaps , lotions , etc ., that are accessible by users of the lavatory unit through access ports in the amenities cabinet 30 . in operation , maintenance personnel may perform the necessary replenishment of the amenities within the lavatory unit 20 by simply removing a previous amenities module 40 and installing a new amenities module 30 within the amenities cabinet 30 . fig2 and 3 illustrate an alternate embodiment of an amenities cabinet system 70 . the amenities cabinet system 70 includes a bracket 71 that is affixed to a bulkhead of a lavatory above a sink 72 . the cabinet system 70 also includes a removable module 73 that is slideably received by the bracket 71 . in one embodiment , the bracket 71 is c - shaped having an opening that faces a user of the sink 72 . a base section of the bracket 71 includes access holes to allow a user access to amenities that are included within the module 73 . the bracket 71 includes mechanism for allowing the module 73 to lock into place . the module 73 includes access openings that are exposed at the opening of the bracket 71 . the access openings may include access to various items stored within the module 73 , such as toilet seat covers , tissues , lotions , soap , paper towels , etc . at a cross - sectional end of the bracket 71 , a side of the module 73 is exposed . at the exposed side of the module 73 , the module may include an access port that provides access to spare toilet paper rolls . as one toilet paper roll is removed from the side of the module 73 , another toilet paper roll stored within the module 73 falls into place at that opening . embodiments of apparatus and methods in accordance with the present invention may provide significant advantages over prior art lavatory units . for example , the lavatory unit in accordance with the present invention may reduce turnaround time for performing necessary maintenance on the lavatories between flights . more specifically , since there is no need for the maintenance personnel to restock the amenities within the lavatory by hand during the maintenance interval between flights , the time required to perform the necessary maintenance is reduced . it will be appreciated that a wide variety of lavatory units may be conceived in accordance with the present invention , and that the invention is not limited to the particular embodiments described above and shown in fig1 - 3 . for example , fig4 is an isometric view of a lavatory unit 100 in accordance with an alternate embodiment of the invention . in this embodiment , the lavatory unit 100 has many of the same components as the embodiment described above with reference to fig1 . for the sake of brevity , only significant differences will be discussed in detail . as shown in fig4 , the lavatory unit 100 includes an amenities cabinet 130 having an first opening 132 disposed in a first wall 134 leading into a passenger cabin 135 of an aircraft . a plurality of access ports 133 are disposed in a second wall 135 of the amenities cabinet 120 . as described above , a first module 140 ( fig1 ) is slideably received into the first opening 132 . in fig4 , the first module 140 is shown in a closed or installed position . the first module 140 includes a plurality of compartments 141 disposed therein that are aligned with the access ports 133 in the second wall 135 . as further shown in fig4 , the lavatory unit 100 also includes a trash receptacle 110 formed in the first wall 134 . a second module 120 ( shown in an open or uninstalled position ) is slideably received into a second opening 122 in the first wall 134 , and is adapted to receive trash that an occupant of the lavatory unit 100 deposits into the trash receptacle 110 . in operation , when the first module 140 is positioned in the amenities cabinet 130 , the compartments 141 containing various amenity items ( e . g . tissues , paper towels , soaps , lotions , etc .) are aligned with the access ports 133 , allowing an occupant of the lavatory unit 100 to access the amenities within the first module 140 . as described above , the first module 140 might suitably be used to efficiently stock amenities within the amenities cabinet 130 in the manner described above . also , the second module 120 may be used to receive trash discarded by aircraft passengers . maintenance personnel may quickly and efficiently remove the trash from the lavatory unit 100 by removing the second module 120 and replacing it with an empty module . for both the restocking and trash removal tasks , the maintenance personnel may perform these operations from the passenger cabin 135 without entering the lavatory unit 100 . in this way , further improvements to the efficiency of the maintenance process may be achieved , and the turnaround time of the aircraft may be reduced . fig5 illustrates a view of an amenities module loading cart 280 . the amenities module loading cart 280 includes a top surface 282 for supporting the amenities module 40 . the amenities module loading cart 280 includes wheels 284 and is sized to allow aircraft personnel to wheel an amenities module 40 and a trash module 288 on the amenities module loading cart 280 into an aircraft and to a position adjacent to the exterior wall 34 of the lavatory unit 220 . the amenities module loading cart 280 is sized vertically to allow aircraft personnel to slide a fully replenished amenities module 40 into the amenities cabinet 30 without having to lift or drop the amenities module 40 into the opening 32 . in an alternate embodiment , the amenities module loading cart 280 includes a height adjustment mechanism ( not shown ) for adjusting the height of the top surface 282 , thereby allowing aircraft personnel to adjust the height of an amenities module 40 on the amenities module loading cart 280 to match the opening 32 of the amenities cabinet 30 . in still another embodiment , the top surface 82 is sized to support two amenities modules 40 . aircraft personnel may then remove a used module from the amenities cabinet 30 onto one side of the top surface 82 , and then may move the amenities module loading cart 280 to allow a newly replenished module 40 that is on the other half of the top surface 282 into position to slide the new module 40 into the amenities cabinet 30 . the amenities module loading cart 280 includes a rotating tray 290 . two modules 40 are placed on the rotating tray 290 in a linear relationship to the cart 280 to allow the cart 280 to maneuver within the aisles of the aircraft . when the cart 280 is located at the proper position for allowing the removal and insertion of modules 288 and 40 into the lavatory , the rotating tray 290 is rotated 90 ° to allow a module 40 to be slideably removed from the amenities cabinet 30 and placed on the tray 290 and vice versa . the trash module 288 is loaded onto a lower portion of the cart 280 at a height for allowing for it to be slideably received and removed from the second opening 122 . a wide variety of apparatus may be conceived that include lavatory units in accordance with alternate embodiments of the present invention . for example , fig6 is a side elevational view of an aircraft 600 having one or more lavatory units 602 formed in accordance with alternate embodiments of the present invention . in general , except for the lavatory units formed in accordance with the present invention , the various components and subsystems of the aircraft 600 may be of known construction and , for the sake of brevity , will not be described in detail herein . embodiments of lavatory units 602 in accordance with the present invention , including but not limited to those embodiments described above and shown in fig1 - 5 . more specifically , as shown in fig6 , the aircraft 600 includes one or more propulsion units 604 coupled to a fuselage 605 , wing assemblies 606 ( or other lifting surfaces ), a tail assembly 608 , a landing assembly 610 , a control system 612 ( not visible ), and a host of other systems and subsystems that enable proper operation of the aircraft 600 . a plurality of lavatory units 602 formed in accordance with the present invention are located within the fuselage 605 and distributed throughout the various portions of the aircraft 600 . although the aircraft 600 shown in fig6 is generally representative of a commercial passenger aircraft , including , for example , the 737 , 747 , 757 , 767 , 777 , and 7e7 models commercially - available from the boeing company of chicago , ill ., the inventive apparatus and methods disclosed herein may also be employed in the assembly of virtually any other types of aircraft . more specifically , the teachings of the present invention may be applied to the manufacture and assembly of other passenger aircraft , cargo aircraft , rotary aircraft , and any other types of aircraft , including those described , for example , in the illustrated encyclopedia of military aircraft by enzo angelucci , published by book sales publishers , september 2001 , in jane &# 39 ; s all the world &# 39 ; s aircraft published by jane &# 39 ; s information group of coulsdon , surrey , united kingdom , which texts are incorporated herein by reference . it may also be appreciated that alternate embodiments of apparatus and methods in accordance with the present invention may be utilized in the other applications , including , for example , ships , buses , trains , recreational vehicles , subways , monorails , or any other desired application . while preferred and alternate embodiments of the invention have been illustrated and described , as noted above , many changes can be made without departing from the spirit and scope of the invention . accordingly , the scope of the invention is not limited by the disclosure of these preferred and alternate embodiments . instead , the invention should be determined entirely by reference to the claims that follow .