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Twin-engine Boeing 767-300ER over Alaska beginning a trans-Pacific crossing

ETOPS^[1] is an acronym for extended operations^[2] as re-defined by the US Federal Aviation Administration (FAA) in 2007.^[3] 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, ATR) to fly long-distance routes that were previously off-limits to twin-engined aircraft. ETOPS operation has no direct correlation to water or distance over water. It refers to single-engine flight times between diversion airfields, regardless as to whether such fields are separated by water or 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."^[4] Prior to 2007, FAA defined ETOPS as "Extended Range Operations with two-engine airplanes" and applied to twins only. International Civil Aviation Organization (ICAO) Standard and Recommended Practice (SARP) applies only to twins and defines ETOPS as "Extended-range Twin-engine Operational Performance Standards".

ETOPS applies to twins on routes with diversion time more than 60 minutes at one engine inoperative speed. For rules that also cover more than two engines, as in the case of the FAA, ETOPS applies on routes with diversion time more than 180 minutes for airplanes with more than two engines.

Until the mid-1980s, the term EROPS (extended range operations) was used before being superseded by ETOPS usage.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 LROPS or Long Range Operational Performance Standards, which would affect all civil airliners, not just those with a twin-engine configuration with more than 180 minutes ETOPS.  According to the FAA in 2007, "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."^[5]

Government-owned aircraft (including military) do not have to adhere to ETOPS regulations.

History[link]

The first direct transatlantic air crossing was made in 1919, by John Alcock and Arthur Brown, in a twin-engined Vickers Vimy. It took sixteen hours. Due to the unreliability of piston engines at the time, long-distance flight using twin engines was considered very risky. More than two engines were seen as a must for flight over long distances and inhospitable terrain, or over the ocean.

In 1953 the US Federal Aviation Administration, having recognized piston engine limitations, introduced the 60-minute rule for 2-engine aircraft. This rule stated that the flight path of twin-engined aircraft should not be farther than 60 minutes of flying time from an adequate airport. This forced these aircraft, on certain routes, to fly a dogleg path to stay within regulations; they were totally excluded from certain routes due to lack of en-route airports. The 60-minute rule was also called the 60-minute diversion period. The totally excluded area was called the exclusion zone.

In the 1950s Pan Am flew Convair 240s across the Caribbean, from Barranquilla to Kingston, and Avensa flew 340s from Maracaibo to Montego Bay; if the 60-minute rule applied to them it must have been 60 minutes at all-engine speed (Barranquilla to Kingston was about 808 km with almost no other airports to help). Delta's Convair from New Orleans to Havana flew a longer trip but could arc north to stay within reach of an airport.

Early turbine engine experience[link]

This section's factual accuracy is disputed. Please help to ensure that disputed facts are reliably sourced. See the relevant discussion on the talk page.

Jet turbine engines in the 1950s and 1960s demonstrated that they had much higher thrust and reliability than any then-available piston engines. Pratt & Whitney jet engines were then reliably powering the 2-engined Boeing 737 series, the 2-engined DC-9 and 3-engined Boeing 727. The 60-minute rule was waived in 1964 for 3-engined aircraft. This opened the way for the development of wide-body intercontinental trijets such as the Lockheed Tristar and DC-10. By then, only 2-engined jets were restricted by the 60-minute rule.

Early twin-engine high-bypass turbofan airliners[link]

When the FAA restricted the twins to 60 minutes in 1953, ICAO limited it to 90 minutes at all-engine speed. Countries outside the US, which adopted the ICAO standards, permitted their airlines to operate up to 90 minutes. This allowed many twins to be operated in Southeast Asia and Australia without significant restriction.

Early ETOPS experience[link]

Boeing 767-300ER, the ETOPS pioneer

The FAA and ICAO concluded that a properly designed twin-engined airliner can make intercontinental transoceanic flights. In 1985 the FAA was first to approve ETOPS guidelines spelling out conditions for allowing a 120-minutes diversion period, sufficient for most transatlantic flights. TWA was awarded the first ETOPS rating in May 1985 for the Boeing 767 service between St. Louis and Frankfurt, allowing TWA to fly its aircraft up to 90 minutes away from the nearest airfield: this was later extended to 120 minutes after a federal evaluation of the airline's operating procedures.

ETOPS extensions[link]

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. This made 95% of the Earth's surface available to ETOPS flights. The first such flight was conducted in 1989. This set of regulations was subsequently adopted by the Joint Aviation Authorities (JAA), ICAO and other regulatory bodies.

In this manner the Boeing 737, 757 and 767 series and the Airbus A300-600, A310, A320 and A330 series were approved for ETOPS operations. The success of ETOPS aircraft like 767 and 777 killed the intercontinental trijets. This ultimately 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 cornerstone of the ETOPS approach is the statistics that show that the turbine itself is an inherently reliable component, and it is the engine ancillaries that have a lower reliability rating. Therefore an engine for a modern twin jet airliner has twin sets of all ancillaries mounted in the engine, which gives the required reliability rating.

The North Atlantic airways are the most heavily used oceanic routes in the world. Most North Atlantic airways are covered by ETOPS 120-minute rules, removing the necessity of using 180-minute rules. However, some of the North Atlantic diversion airports, especially Kangerlussuaq Airport, are subject to adverse weather conditions making them unavailable for use. As the 180-minute rule is the upper limit, the JAA & FAA has 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.

ETOPS-240 and beyond are now permitted^[6] on a case-by-case basis, with regulatory bodies in nations ranging from the USA, 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.

Early ETOPS[link]

Boeing 777-200ER.

The original 1985 regulations allowed an airliner to have ETOPS-120 rating on entry into service. ETOPS-180 was only possible after 1 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 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.

Today regulations in Europe and US permit up to 180-minute ETOPS at entry.

ETOPS exclusions[link]

Private jets are exempted from ETOPS by the FAA, but are subject to the ETOPS 120-minute rule in JAA's jurisdiction.

Until the rule change in US, Australia, several commercial airline routes were still economically off-limits to twinjets because of ETOPS regulations. There were routes traversing the South Pacific (e.g., Sydney – Santiago de Chile, which is the longest over-the-sea distance flown by a commercial airline), South Atlantic (e.g., Capetown – São Paulo), Southern Indian Ocean (e.g., Perth – Johannesburg), and Antarctica.

Beyond ETOPS-180[link]

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. Airbus is planning to certify its A350XWB to 350-minute ETOPS, while Boeing is planning to certify its 787 to 330-minute ETOPS.^[7]

On December 12, 2011, Boeing received type-design approval from the U.S. Federal Aviation Administration (FAA) for up to 330-minute extended operations for its 777 fleet. This certification applies to the 777-200LR, 777-300ER, 777F and 777-200ER equipped with GE engines.^[8]

EASA also has updated its twin-engine (ETOPS) rules. It has not formally declared its timing for ETOPS type rules for airplanes with more than two engines, or whether it will use the acronym ETOPS or LROPS for these operations.

ETOPS ratings[link]

The following ratings are awarded under current regulations according to the capability of the airline:

• ETOPS-75
• ETOPS-90
• ETOPS-120/138
• ETOPS-180/207
• ETOPS-240
• ETOPS->240

However, ratings for ETOPS type approval are fewer. They are:

• ETOPS-90, which keeps pre-ETOPS Airbus A300B4 legally operating under current rules
• ETOPS-120/138
• ETOPS-180/207, which covers 95% of the Earth's surface.
• ETOPS->180 to Design Limit

Approval for ETOPS[link]

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 should be able to fly with full load and just one engine for 3 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 on top of 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, 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.

References[link]

• New ETOPS regulations, Jan. 26, 2007 – The new FAA ETOPS ruling
• "FAA frees twins from ETOPS limits", Flight International Jan. 16–22, 2007, Reed Publication Limited
• Airbus:LROPS – Airbus page on LROPS (Long Range Operations)

External links[link]

• Great Circle Mapper – includes ETOPS ranges