An employee vacuums an aisle carpet inside the economy class section of an Airbus A380-800 aircraft, operated by Emirates, as the plane is prepared for its next flight from Terminal 3 of Heathrow Airport in London, U.K., on Thursday, Dec. 5, 2013. Emirates, the world’s largest buyer of Airbus A380 aircraft, is exploring engine options for a batch of 50 additional superjumbos, handing Rolls-Royce Holdings Plc an opportunity to unseat a General Electric Co. and Pratt & Whitney joint venture that powers the existing jets. Photographer: Paul Thomas/Bloomberg