Boeing and Airbus have a backlog of around 4,500 orders for 110-180 seat single aisle jets, split more of less equally, stretching to 2015 at current production rates. Neither Boeing nor Airbus has had much interest in offering anything new. But developments beyond their control are now farcing them to rethink. Two new single aisle jets from China and Russia, both expected to enter service in 2016, are aimed at the two aviation giants. The Commercial Aircraft Corporation of China is building the 170-190 seat C919 and United Aircraft Corporation of Russia a 150-212 seat Irkut MS-21. Both claim their planes will consume 15% less fuel than the current A320 and 737, and they will be much cheaper.