thumb|250px|twin-engine boeing 767-300er over alaska beginning a trans-pacific crossing etops is an aviation acronym for extended range twin operationsuk caa defines etops as "extended range twin operations" , easa defines it as "extended range operation with two-engine aeroplanes" and icao as "extended-range twin-engine operational performance standards" as re-defined by the us federal aviation administration (faa) in 2007. this rule allows twin-engined airliners (such as the airbus a300, a310, a320, a330 and a350, the boeing 737, 757, 767, 777, 787, the embraer e-jets, and the atr 72) to fly long-distance routes that were previously off-limits to twin-engined aircraft. there are different levels of etops certification, each allowing aircraft to fly on routes that are a certain amount of single-engine flying time away from the nearest suitable airport. for example, if an aircraft is certified for 180 minutes, it is permitted to fly any route not more than 180 minutes single-engine flying time to the nearest suitable airport. etops operation has no direct correlation to water or distance over water. it refers to flight times between diversion airfields, regardless as to whether such fields are separated by water or land. in aviation vernacular, the colloquial backronym is "engines turning or passengers swimming," referring to the inevitable emergency water landing of a twin engine aircraft after a double engine failure over water outside gliding range of land. according to the faa in the federal register, "this final rule applies to air carrier (part 121), commuter, and on-demand (part 135) turbine powered multi-engine airplanes used in extended-range operations. however, all-cargo operations in airplanes with more than two engines of both part 121 and part 135 are exempted from the majority of this rule. today's rule [january 16, 2007] establishes regulations governing the design, operation and maintenance of certain airplanes operated on flights that fly long distances from an adequate airport. this final rule codifies current faa policy, industry best practices and recommendations, as well as international standards designed to ensure long-range flights will continue to operate safely." prior to 2007, faa defined etops as "extended range operations with t
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