Extended-range Twin-engine Operational Performance Standards dictate how far an aircraft can fly away from land to land should an engine fail. Another informal way to remember the acronym is “Engines Turn or Passengers Swim”. When global passenger flights first started the only aircraft flying across the ocean was the Boeing 747, this was followed by the quad-engines Airbus A340. However, twin-engine aircraft were always limited by the fact that an engine failure would put the aircraft in a compromising position unable to land.  ETOPS was designed to gauge how long an aircraft can effectively fly with one-engine inoperative. The certification was given in minutes and twin-engine aircraft had to stay close to land. However, aircraft can operate for hours with only a single engine, and can effectively fly across the ocean with an engine failure.