A pallet of cargo rolls onto a one of two elevating transfer vehicles May 4, 2015, at the 436th Aerial Port Squadron on Dover Air Force Base, Del. Pallets are temporarily housed in a multi-level pallet grid terminal where a computer system remembers exactly where the specific pallet is stored. When the pallet is ready to be loaded onto an aircraft, the ETV retrieves the pallet in the required order to be loaded onto a cargo loader, and then onto an aircraft. (U.S. Air Force photo/Roland Balik)