CHICAGO, June 20, 2013 /PRNewswire/ -- United Airlines (NYSE: UAL) today announced an order with Airbus for new A350-1000 aircraft. The agreement converts United's existing order for 25 A350-900s into A350-1000s and adds 10 firm orders for A350-1000s, giving the airline a total order of 35 aircraft. The increased seating capacity of the A350-1000 will enable United to replace older, less efficient aircraft currently serving long-range, high-demand markets. United expects delivery starting in 2018. "We look forward to taking delivery of the A350-1000," said Jeff Smisek, United's chairman, president and CEO. "This is a modern, fuel-efficient and advanced-technology aircraft that our customers and co-workers will enjoy flying. It will be a great addition to our fleet, and will allow us to meet demand on larger, long-haul markets in our world-leading network." A rendering of the A350-1000 is available for download here.The A350-1000 in United's fleet The A350-1000 is the largest member of the A350 WXB family and uses advanced materials including composites, titanium and aluminum alloys combined with the latest engine technology to make it lighter and more fuel efficient. The aircraft will consume approximately 20 percent less fuel per seat than the large widebody aircraft it will replace. It is powered by new-generation Rolls-Royce Trent engines. The cabin will offer an improved customer experience with more headroom, wider panoramic windows and more overhead storage space. "Less than a week after the success of the A350 XWB's first flight, we see that demand for the new aircraft continues to grow, especially for the larger -1000 model. Airbus is proud to have United Airlines on board the exciting A350 program in such a significant way," said Fabrice Bregier, Airbus President and CEO. Fleet modernization The Airbus order supports United's commitment to improve the overall efficiency of its fleet. On Tuesday, the airline announced an order for 10 Boeing 787-10 aircraft and conversion of 10 existing 787 orders to the -10 variant, making United's total Dreamliner order book 65. In July of last year, United announced a narrowbody order for 100 Boeing 737 MAX 9 aircraft and 50 Boeing 737-900ER aircraft. The airline is also modernizing its United Express fleet by adding seventy 76-seat Embraer aircraft that will be operated by regional partners.