The airline announced the order of 19 Boeing 777-300ER aircraft in August 2004 with the order signed on 23 December 2004, during which an unused option for the Boeing 777 family was converted into an order for a Boeing 777-300ER. Singapore Airlines became the world's largest operator of the Boeing 777 when it took delivery of its 58th such aircraft, a Boeing 777-300, on 6 May 2005. It has since been surpassed by Emirates, which as of November 2017 has 159 examples in its fleet. The airline's new Boeing 777-300ERs entered commercial service on 5 December 2006.