The 767-300ER, the extended-range version of the 767-300, entered service with American Airlines in 1988. The type's increased range is made possible by greater fuel capacity and a higher Maximum Take Off Weight of 407,000 pounds (185,000 kg), giving it a maximum range of 7,260 statute miles (11,690 km). Design improvements allowed the available Maximum Take Off Weight to increase to 412,000 pounds (187,000 kg) by 1993. Power is provided by either Pratt & Whitney PW4000, General Electric CF6, or Rolls-Royce RB211 engines.Typical routes for the type include Los Angeles to Frankfurt. The combination of increased capacity and range offered by the 767-300ER has been particularly attractive to both new and existing 767 operators, allowing it to become the most successful version of the 767 family of aircraft. Airlines have placed more orders for the type than all other 767 variants combined. As of September 2014, 767-300ER deliveries stand at 583 with no unfilled orders and airlines had 495 examples in service as of July 2014. The type's main competitor is the Airbus A330-200.