Originally Posted by
JDiver
In my opinion, that’s not really accurate. ETOPS rating is based on a nipumber of factors, including a different maintenance schedule, etc. The 777 was nominated and initially approved for ETOPS 180 “out of the box” as long as all ETOPS requirements are met, but the Joint Aviation Authorities (JAA) disagreed and the Boeing 777 was rated ETOPS 120 in Europe upon service entry. The model has proved itself, and Air New Zealand ultimately secured ETOPS 330 for their Rolls-Royce Trent 800 powered 777-200ER powered by engines AKL-EZE.
All that is correct, but the point is that four engines are safer than two. It was considered very risky to assume that only one engine will fail on a twin-engine aircraft. There have been incidents where both engines failed while flying. Even with the B777. Even with a highly reputable and experienced airline like BA using Rolls Royce Trent engines. Nevertheless, the FAA allowed ETOPS and eventually the rest of the world got in line. And so far there haven't been any disasters related to the newer ETOPS rules.
As you may know, ETOPS also stands for Engines Turn Or People Swim.