The Chinese OEM COMAC continues to build momentum around its narrowbody twin jet C919. Orders from ICBC Leasing and Sichuan Airlines during October have added 65 orders to the backlog and brings the overall order book to 175 units including options. The C919 is scheduled for first flight in 2014 (first commercial delivery planned in 2016) and is the most significant challenge to the strengths of both Airbus and Boeing in the mainstream short-haul marketplace, writes JOE GILL.