ETOPS
Rules letting twin-engine jets fly long routes far from airports.
ETOPS (Extended-range Twin-engine Operational Performance Standards) is a certification that allows twin-engine aircraft to fly routes that take them a specified maximum flying time away from the nearest suitable diversion airport — for example ETOPS-180 means up to 180 minutes on one engine. It is what enables modern twinjets like the 787 and A350 to fly transoceanic routes once reserved for three- and four-engine aircraft.