ETOPS is an acronym used in aviation for Extended Operations. The ICAO coined the acronym for Extended Twin Operations for twin-engine aircraft operation further than one hour from a diversion airport at the one-engine inoperative cruise speed, over water or remote lands, on routes previously restricted to three- and four-engine aircraft. The ICAO issues Standards and Recommended Practices (SARPS) for ETOPS, and ETOPS were extended to four-engine aircraft like the Boeing 747-8.
The first non-stop transatlantic flight was made in 1919, by John Alcock and Arthur Brown, in a twin-engined Vickers Vimy, from Newfoundland to Ireland in sixteen hours. By 1936, the FAA restricted operations to within 100 mi (160 km) of an airport, regardless of the engine number, about 60 minutes with one engine inoperative. In 1953, the FAA "60-minute rule" restricted twin-engine aircraft to a 60-minute diversion area, based on the piston engine reliability of the time, with flexibility beyond with special approval. In the 1950s, the ICAO recommended a 90-minute diversion time for all aircraft, adopted by many regulatory authorities and airlines outside the US.
At that time, Pan Am flew twin-piston Convair 240s across the Caribbean, from Barranquilla to Kingston, Jamaica, and Avensa flew the stretched Convair 340s from Maracaibo to Montego Bay. Delta's Convair from New Orleans to Havana flew a longer trip but could arc north to stay within reach of an airport.
By the 1960s, all large civilian aircraft were jet powered, relegating the piston engine to low-cost niche roles such as cargo flights. The JT8D was reliably powering the three-engined Boeing 727. The 60-minute rule was waived in 1964 for three-engined aircraft, which opened the way for the development of wide-body, intercontinental trijets, such as the Lockheed L-1011 Tristar and DC-10. By then, only two-engined jets were restricted by the 60-minute rule.
Dick Taylor, then Boeing's director of engineering approached FAA director J. Lynn Helms in 1980 about the possibility of an exemption, whose response was "It'll be a cold day in hell before I let twins fly long haul, overwater routes."  The Boeing 767-200ER entered service in 1984.
In 1985, the FAA increased the ETOPS to 120 minutes at the single-engine cruise speed. Trans World Airlines operated the first ETOPS (90 minutes) service in February 1985 with a Boeing 767, followed by Singapore Airlines in June with an A310. In April 1986, Pan Am inaugurated transatlantic revenue service using A310s and Airbus ETOPS operators were more than 20 in less than five years.
In 1988, the FAA amended the ETOPS regulation to allow the extension to a 180-minute diversion period subject to stringent technical and operational qualifications. ETOPS-180 and ETOPS-207 cover about 95% of the Earth. The first such flight was conducted in 1989. This set of regulations was subsequently adopted by the JAA, ICAO and other regulatory bodies.
The original 1985 regulations allowed an airliner to have ETOPS-120 rating on entry into service. ETOPS-180 was only possible after one year of trouble-free 120-minute ETOPS experience. In 1990 Boeing convinced the FAA that it could deliver an airliner with ETOPS-180 on its entry into service. This process was called Early ETOPS. The Boeing 777 was the first aircraft to carry an ETOPS rating of 180 minutes at its introduction.
In the 1990s the Joint Aviation Authorities (JAA) disagreed and the Boeing 777 was rated ETOPS-120 in Europe on its entry into service. European airlines operating the 777 had to demonstrate one year of trouble-free 120-minutes ETOPS experience before obtaining 180-minutes ETOPS for the 777.
Effective February 15, 2007, the FAA ruled that US-registered twin-engined airplane operators can fly more than 180-minute ETOPS to the design limit of the aircraft.
ETOPS-240 and beyond are now permitted on a case-by-case basis, with regulatory bodies in nations ranging from the US, to Australia, to New Zealand adopting said regulatory extension. Authority is only granted to operators of two-engine airplanes between specific city pairs. The certificate holder must have been operating at 180-minute or greater ETOPS authority for at least 24 consecutive months, of which at least 12 consecutive months must be at 240-minute ETOPS authority with the airplane-engine combination in the application.
On December 12, 2011, Boeing received type-design approval from the U.S. FAA for up to 330-minute extended operations for its Boeing 777-200LR, 777-300ER, 777F and 777-200ER equipped with GE engines, and with Rolls-Royce and Pratt & Whitney engines expected to follow. The first ETOPS-330 flight took place on December 1, 2015 with Air New Zealand connecting Auckland to Buenos Aires on a 777-200ER. On May 28, 2014, the Boeing 787 Dreamliner received its ETOPS-330 certificate from the FAA, enabling LAN Airlines to switch to the 787 from the A340 on their Santiago - Auckland - Sydney service a year later. Until the rule change in the US and Australia, several commercial airline routes were still economically off-limits to twinjets because of ETOPS regulations. There were routes traversing the Southern hemisphere, e.g., South Pacific (e.g., Sydney - Santiago, which is the longest over-the-sea distance flown by a commercial airline), South Atlantic (e.g., Johannesburg - São Paulo), Southern Indian Ocean (e.g., Perth - Johannesburg), and Antarctica.
Before the introduction of the Airbus A350XWB in 2014, regulations in Europe and US permitted up to 180-minute ETOPS at entry. The A350XWB was first to receive an ETOPS-370 prior to entry into service by European authorities.
The North Atlantic Tracks are the most heavily used oceanic routes in the world. Most North Atlantic Tracks are covered by ETOPS 120-minute rules, removing the necessity of using 180-minute rules. However, some of the North Atlantic diversion airports are subject to adverse weather conditions making them unavailable for use. As the 180-minute rule is the upper limit, the JAA and FAA have given 15% extension to the 120-minute rules to deal with such contingencies, giving the ETOPS-138 (i.e. 138 minutes), thereby allowing ETOPS flights with such airports closed.
The Airbus A300-600, A310, A320 and A330 series and the Boeing 737NG/MAX, 757 and 767,787,777 ER/X series were approved for ETOPS operations. The success of ETOPS aircraft like A300 and 767 made the intercontinental trijets obsolete for passenger use. This led Boeing to end the MD-11 program a few years after Boeing's merger with McDonnell Douglas, as well as to scale down the production of its own Boeing 747.
The rules have also allowed American legacy carriers (United Airlines and Delta Air Lines in particular) to use the Boeing 757 on "long and thin" transatlantic routes between their major hubs and secondary European cities that cannot generate the passenger demand to justify the use of a widebody airliner. The practice has been controversial, because although the 757 has adequate range to cross the Atlantic Ocean comfortably, strong headwinds caused by the jetstream over the winter months can result in westbound flights being declared "minimum fuel", forcing a refuelling stop at Gander, Newfoundland, in order to safely complete their journey.
Aloha Airlines operated 180 minute ETOPS approved Boeing 737-700 aircraft on nonstop routes between the Hawaiian Islands and the western U.S. and also Vancouver, Canada. The use of the smaller 737-700 enabled Aloha to serve routes that could not support larger jet aircraft with an example being the Honolulu - Burbank nonstop route. Prior to the 737-700 operation, Aloha Airlines had operated 737-200 aircraft to various Pacific islands utilizing 120 minute ETOPS.
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The cornerstone of the ETOPS approach is the statistics showing that the turbine assembly of a modern jet engine is an inherently reliable component. Engine ancillaries, by contrast, have a lower reliability rating. Therefore, an ETOPS-certified engine may be built with duplicate sets of certain ancillaries in order to receive the required reliability rating.
ETOPS approval is a two-step process. First, the airframe and engine combination must satisfy the basic ETOPS requirements during its type certification. This is called "ETOPS type approval". Such tests may include shutting down an engine and flying the remaining engine during the complete diversion time. Often such tests are performed in the middle of the ocean. It must be demonstrated that, during the diversion flight, the flight crew is not unduly burdened by extra workload due to the lost engine and that the probability of the remaining engine failing is extremely remote. For example, if an aircraft is rated for ETOPS-180, it means that it is able to fly with full load and just one engine for three hours.
Second, an operator who conducts ETOPS flights must satisfy their own country's aviation regulators about their ability to conduct ETOPS flights. This is called "ETOPS operational certification" and involves compliance with additional special engineering and flight crew procedures in addition to the normal engineering and flight procedures. Pilots and engineering staff must be qualified and trained for ETOPS. An airline with extensive experience operating long distance flights may be awarded ETOPS operational approval immediately, while others may need to demonstrate ability through a series of ETOPS proving flights.
Regulators closely watch the ETOPS performance of both type certificate holders and their affiliated airlines. Any technical incidents during an ETOPS flight must be recorded. From the data collected, the reliability of the particular airframe-engine combination is measured and statistics published. The figures must be within limits of type certifications. Of course, the figures required for ETOPS-180 will always be more stringent than ETOPS-120. Unsatisfactory figures would lead to a downgrade, or worse, suspension of ETOPS capabilities either for the type certificate holder or the airline.
Engines must have an In-flight shutdown (IFSD) rate better than 1 per 20,000 hours for ETOPS 120, 1 per 50,000 hours for ETOPS 180 and 1 per 100,000 hours for beyond 180.
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.
The following ratings are awarded under current regulations according to the capability of the airliner:
However, ratings for ETOPS type approval are fewer. They are:
Until the mid-1980s, the term EROPS (extended range operations) was used before being superseded by ETOPS usage. In 1997, when Boeing proposed to extend ETOPS authority for twins to beyond 180 minutes, Airbus proposed to replace ETOPS by a newer system, referred to as Long Range Operational Performance Standards (LROPS), which would affect all civil airliners, not just those with a twin-engine configuration with more than 180 minutes ETOPS.
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."
Several commenters ... recommended use of the acronym "LROPS"--meaning 'Long Range Operations'--for three- and four-engine ETOPS, to avoid confusion, particularly for those operations beyond 180-minutes diversion time. The FAA has decided to use the single term, 'extended operations,' or ETOPS, for all affected operations regardless of the number of engines on the airplane."
Prior to 2007, the FAA used the term for Extended Range Operation with Two-Engine Airplanes but the meaning was changed when regulations were broadened to include aircraft with more than two engines.
In aviation vernacular, the colloquial backronym is "Engines Turn Or Passengers Swim", referring to the inevitable emergency water landing of a twin engine aircraft after a double engine failure over water outside gliding range of land.
ETOPS option shades no-go areas