The 777 is also noteworthy for being the first
twin-engined turbofan airliner to be certified by the
U.S. FAA and
DOT for extended
transoceanic flight (as in, beyond the short North Atlantic route). This is due to its ability to continue flying for extremely long distances with one engine off - a high
ETOPS rating.
Potential advantages of the twin configuration (as opposed to the 747's 2x2, or the DC-10's 1x1x1 include better fuel efficiency, lower noise, a less complex aircraft which means fewer failures, less weight, etc., and more easily synchronized thrust.