The Boeing 777 is a long-range wide-body twin-engine jet airliner designed and manufactured by Boeing Commercial Airplanes, the commercial business unit of Boeing. Commonly referred to as the "Triple Seven", it is the largest twinjet. The 777 can accommodate between 301 and 450 (Air Canada High Density) passengers in a three-class layout, and has a range of , depending on the model. Developed in consultation with eight major airlines, the 777 was designed to replace older wide-body airliners and bridge the capacity difference between the 767 and 747. The 777 is produced in two fuselage lengths. The original 777-200 model first entered service in 1995, followed by the extended-range 777-200ER in 1997. The stretched 777-300, which is longer, began service in 1998. The longer-range 777-300ER and 777-200LR variants entered service in 2004 and 2006, respectively, while a freighter version, the 777F, debuted in 2009. United Airlines first placed the 777 into commercial airline service in 1995. The most successful variant is the 777-300ER with 799 aircraft delivered and over 844 orders to date. Emirates operates the largest 777 fleet with 148 aircraft. FedEx Express operates the largest fleet of the 777F cargo aircraft. As of June 2019, 2,033 Boeing 777s, of all variants, have been ordered and 1,598 have been delivered. Model summary United Airlines placed the launch order for the 777 program on October 14, 1990 when it purchased 34 Pratt & Whitney PW4084-powered 777-200s valued at US$11 billion with options on an additional 34. Subsequent versions of the 777, including the 777-200ER, 777-200LR, 777-300, 777-300ER, 777F and the upcoming 777-8X and -9x, have been launched by Air France, British Airways, Cathay Pacific, and Pakistan International Airlines (PIA). The following table lists milestone dates for each model of the aircraft. Current and future operators The 777-200 entered into service with United Airlines on June 7, 1995 with its first flight from London Heathrow Airport to Dulles International Airport. From day one, the 777 was awarded 180-minute ETOPS clearance by the Federal Aviation Administration, making it the first airliner to carry an ETOPS-180 clearance into service. This would later be increased to 207 minutes by October 1996. British Airways placed the first model with General Electric GE90-77B engines into service on November 17, 1995. The first Rolls-Royce Trent 877-powered aircraft was delivered to Thai Airways International on March 31, 1996, completing the introduction of the three power-plants initially developed for