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Extended Range Operation with Two-Engine Airplanes

The term ETOPS signified "Extended Range Operation with Two-Engine Airplanes" (ETOPS = Engines Turn or Passengers Swim). ETOPS guidance has been used for over twenty years to allow two-engine airplanes in part 121 operations to deviate from the regulation that limited the distance these airplanes could fly from potential diversion airfields. By the year 2000, in-service engines are capable of achieving better than 100,000 hours time between shutdowns (.01/1,000 engine-hours), or double the current ETOPS reliability standard. This represents two in-flight shutdowns in the entire life of a typical transport airplane. It is not reasonable to expect that two in-flight shutdowns due to independent causes in the entire life of a typical transport airplane would occur on the same flight.

In the 1980s, a new generation of very reliable, two engine airplanes came into service and changed the underlying premise that restricted the operations of these airplanes. The airline industry sought to take advantage of the improvements in reliability, range, and payload capabilities that these new airplanes offered. Beginning in 1985, the FAA allowed air carriers to operate certain twin-engine airplanes on routes that included points more than sixty-minutes from an adequate airport under a formal program known as Extended Range Operation with Two Engine Airplanes (ETOPS).

In support of ETOPS, the FAA issued two Advisory Circulars (AC) 120-42 and 120-42A in 1985 and 1988 respectively. These two AC documents have been the basis for type design and operational practices for ETOPS to date. Initially, the FAA set a maximum approval of 120 minutes from an airport for ETOPS. During the nascent stage of ETOPS, air carriers gained significant service experience; the safety and efficiency of ETOPS became apparent. In 1988, the FAA increased that approval to 180 minutes based on demonstrated safety record of these operations.

Regulations issued in 2004 by the U.S. Federal Aviation Administration (FAA) came close to eliminating hard diversion limits on twin-engine aircraft, thus opening up to these aircraft previously unavailable routes to remote and unaccessible areas. According to the FAA, the term for extended twin operations (ETOPS) will now stand for extended operations. The Notice of Proposed Rulemaking (NPRM) issued by the FAA at the same time extended some requirements to those airplanes with more than two engines if they will be operating more than 180 minutes from an adequate airport. The NPRM features three key elements: 1) it codifies all current twinjet ETOPS practices; 2) expands twinjet ETOPS authority to 240 minutes and beyond, and 3) applies similar practices for all three- and four-engine aircraft operating in diversion distances greater than 180 minutes. The NPRM process is coordinated with a similar European initiative under the auspices of the Joint Aviation Authority (JAA). Significant differences, however, existed between the two initiatives that could ultimately affect the harmonization process.

The ETOPS (Extended Twin-engine Operations) market was effectively established by the Boeing 767. ETOPS is sometimes read (humorously) as Engines Turn or Passengers Swim. ETOPS is being replaced by a newer system, referred to as EROPS, or Extended Range OPerationS, which will affect all aircraft, not merely those with a twin-engine configuration.

In 1966 Frank Kolk of American Airlines took the view that the airlines needed something intermediate in size, carrying more passengers than a 707 or a DC-8 but fewer passengers than a 747. He wanted a wide-body layout, featuring a big cabin with two aisles. But whereas those other jets had four engines, his called for only two. In Washington, his concept for a widebody twinjet soon bumped up against federal regulations.

On a number of routes, those that crossed the Rockies or flew over oceans, regulations called for a minimum of three engines to provide safety if an engine shut down in flight. Three-engine designs thus shaped the American jetliners - the McDonnell Douglas DC-10 and Lockheed L-1011 - that grew out of Kolk's initiative. The 3 engine jet came about due to the old FAA "60 minute rule". This rule stated that a twin engine jet had to always be within 60 minutes of a suitable airport. in case of an engine failure. Airlines wanted to go farther and farther, so 60-minute rule didn't apply to the 3-engine jets. Thus, 3-engine jets became very popular. As time went by, jet engines got much more efficient and failure rates went way down.

On other routes, a twinjet indeed could comply with the safety regulations. In Europe, America's regulations did not apply. Outside the USA, other countries followed ICAO regulations, which allowed for a 90 minutes diversion time.

At the French firm of Sud Aviation, the chief engineer Roger Beteille took the lead in urging Europe to build Kolk's big twinjet. Such a project was too big for Sud alone to take on, and Beteille won promises of cooperation from government officials in Britain and Germany. Together they agreed to build such a plane, calling it the Airbus A-300. Airbus was determined from the start that it whould set new standards in technology and innovation. By its very nature, the A300 had done just that by becoming the world's first twin-engine widebody. In 1977, the A300B4 became the first "ETOPS compliant" aircraft - its high performance and safety standards qualified it for Extended Twin Engine Operations over water, providing operators with more versatility in routing.

Obtaining an ETOPS rating requires certification of the reliability of an airframe/engine combination as well as an airline's flight operations and maintenance. Usually extra equipment is required as well, such as additional backup systems for electrical power. ETOPS does not require over-water equipment (e.g., life rafts) or additional fuel tanks, though these are usually required for the typical missions of ETOPS-rated aircraft.

Most of the operator prefers 2 engines to be cost-effective instead of 3 engines.

In May 1985, the U.S. Federal Aviation Administration (FAA) approved 767s for long-range flights of up to 120 minutes from an alternate airport. the first FAA approved ETOPS flight was on 01 February 1985. In March 1989, the FAA approved the 767 as the first jetliner for 180-minute extended operations (ETOPS). This allows more direct, time-saving trans-Pacific and trans-Atlantic flights from many U.S. gateways. After more than 15 years ETOPS has proven successful and is now part of airlines' routine operations. 767s fly more ETOPS flights than any other airplane.

ETOPS design enhancements have increased the robustness of airplane systems and driven further gains in the extreme reliability of modern fanjet engines. ETOPS maintenance requirements also reduce diversions through engine condition and oil level/consumption monitoring, the aggressive resolution of reliability issues, and procedures to avoid human error during maintenance of airplane engines and systems.

Boeing's 777 was the first airliner designed with ETOPS in mind from its inception, including systems to support single-engine operations for considerably longer than 180 minutes. While proposals to extend ETOPS to a 240-minute rule-time haven't met with much success, an interim proposal for 207 minutes (180 minutes plus 15%, similar to the 138 minute rule-time) has been adopted, primarily as an exception for 180-minute routes when key alternate airports are unavailable due to weather.

Airbus twin-engined experience started in 1974 with the A300B4, pre-dating the first ETOPS rules by more than a decade. Today, all wide-bodied Airbus twins (A300-600, A310 and A330) are type-certificated to 180 minutes and all A320 Family aircraft to 120 minutes.

Since the first ETOPS approvals, engine reliability has increased significantly. Consequently, industry asked the FAA to recognize these technological advances and allow two-engine airplanes to fly further from airports than previously allowed. Formerly the term ETOPS signified "Extended Range Operation with Two-Engine Airplanes." ETOPS guidance has been used for over twenty years to allow two-engine airplanes in part 121 operations to deviate from the regulation that limited the distance these airplanes could fly from potential diversion airfields. With over twenty years of successful experience in ETOPS operations, improvements in aircraft technology and reliability, and the prospect of airline operations on routes of increasing distance and remoteness, the FAA and industry agreed that ETOPS guidance should be reviewed, evaluated for potential application to all airplanes, and codified in the regulations. Note that the changes can be characterized by the change in meaning of ETOPS to "Extended Operations" since these provisions have broadened to include aircraft with more than two engines and to include both part 121 and part 135 operations. These regulations were posted in the Federal Register on January 16, 2007.

  • Part 121 - All two-engine airplanes more than 60 minutes flying time from an adequate airport (at a one-engine-inoperative cruise speed under standard conditions in still air). All passenger-carrying airplanes with more than two engines and more than 180 minutes flying time from an adequate airport (at a one-engine-inoperative cruise speed under standard conditions in still air).
  • Part 135 - All multi-engine turbine-engine powered airplanes (other than all-cargo operations with airplanes having more than two engines) more than 180 minutes flying time (limited to 240 minutes flying time) from an airport meeting the requirements of part 135, 135.385 or 135.393 and 135.219 at an approved one-engine-inoperative cruise speed under standard conditions in still air.
On January 8, 2007 the Department of Transportation's Federal Aviation Administration (FAA) published a comprehensive final rule that further reduces the risks for passengers and crews flying long-range regularly scheduled commercial routes over remote areas. The rule effectively changes the current limitations and opens up routes for twin-engine passenger and cargo planes, and sets uniformly high standards for all commercial passenger planes when they fly routes more than three hours from an airport. The new rule takes into account the extraordinary reliability of today's aircraft engines. It covers the design, maintenance and operation of airplanes and engines for extended operations flights - commonly called ETOPS - that go beyond certain distances from the nearest airport. "Twenty-one years of ETOPS experience shows us that modern jet engines rarely shut down in flight," said FAA Administrator Marion C. Blakey. "Our new safety requirements for long-range flights are designed to prevent mechanical problems and protect passengers and the flightcrew in the rare event of an emergency diversion."

Since airplanes occasionally divert for reasons unrelated to the engines, such as mechanical problems or passenger medical emergencies, the rule requires that airplane systems be able to support lengthy diversions in remote and sometimes harsh environments. The rule also requires pro-active flight planning, crew training and plans to have facilities at or close to each diversion airport that will protect passengers and crew from the elements and make them comfortable.

The rule formalizes existing policy, industry best practices and international standards to ensure long-range flights operate safely in the Polar regions, the South Atlantic Ocean between South America and Africa, and the southeastern South Pacific Ocean. Few U.S. carriers currently operate in these areas, but these operations will likely increase in the future. In formulating the new regulations, the FAA sought advice from a broad range of domestic and international aviation experts. In 2000, the FAA chartered an Aviation Rulemaking Advisory Committee (ARAC) to review existing policy and requirements and develop standardized requirements for extended operations in the 21st century. The new rule is based largely on the ARAC's report, which reflects a consensus among those aviation experts on what needed to be done.

The evolution of extended operations has involved a step-by-step process of ever-increasing approvals based on industry needs. Two-engine extended operations increased worldwide from fewer than 1,000 per month in 1985 to more than 1,000 per day in 2004. Meanwhile, extended operations engine reliability has improved to the point that engine shutdowns occur less than half as often as they did in the 1980s.

With the FAA abolishing ETOPS and allowing qualified Twin jets to fly over 5 hours away from a diversion airport, Boeing's long standing vision of point to point travel with fuel efficient twin jets got a big seal of approval. With Boeing's 777s trouncing the Airbus A340, and with the FAA ETOPS announcement, why would any airline purchase the Airbus A340-500 or A340-600? With the Airbus response to a long range twin many years away in the A350 family, Boeing should enjoy a virtual monopoly with the 777/787 family.

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