ETOPS is the min distance / flying time you can be away from a suitable airport with only one engine operational. In the past you couldn't take a two engine jet

ETOPS is the min distance / flying time you can be away from a suitable airport with only one engine operational. In the past you couldn't take a two engine jet over the ocean or had to fly a far north arc to ensure you were close enough to land. The 747 had increased etops as it had four engines so losing thrust in one or more was not as big of a deal. Now that we have years of data related to twin engine performance we now have etops 180 which allows us to take twins across the Atlantic. I write this sitting on a 777 heading to Europe flying a route that 40 years ago wouldn't have been allowed.