| Flight under extended-range twin-engine operations (ETOPS) rules has proven to be routine, safe, and highly successful around the world. ETOPS allows two-engine-airplane operation for up to 180 min from an en route alternate airport. ETOPS has been used successfully on airplanes built by all major airframe manufacturers, including Boeing (737, 757, 767, 777, and MD-80). The 767 is the most widely used airplane for ETOPS, and the world fleet of 767s has just completed its one millionth ETOPS flight. Though twinjets fly ETOPS routes around the world, they dominate in the North Atlantic market and show potential for the same success in the North Pacific ETOPS market.|
Understanding ETOPS expansion includes a review of the following:
Boeing twinjets complete about 600 ETOPS flights a day around the world (figure 1), for a total of more than 18,000 such flights each month and almost 1.25 million flights since 1985. Operators, regulatory authorities, and manufacturers have worked together to achieve a rate of in-flight shutdowns that is well below the target set by regulatory authorities. In addition, the excellent propulsion-related safety record of the twinjets has not only been maintained but potentially enhanced by the process-related provisions associated with ETOPS-type design and operational approvals. Some operators have adopted these ETOPS processes into their three- and four-engine airplane fleets and recorded notable improvements in overall reliability.
Airplane availability affects operators' strategies and the type of service they provide. In the early 1970s, operators had few airplane choices to serve long-range routes between the United States and Europe. Economically efficient twinjets such as the 757 and 767, which had the range for such routes, came onto the market in the early 1980s. With the advent of ETOPS in 1985, operators could use these twinjets efficiently across the North Atlantic. By adding these long-range airplanes with fewer seats, operators offered the traveling public more choices between existing city pairs by increasing the number of flights and providing a wider variety of departure times. Additionally, operators began to add more new city pairs between Europe and North America. ETOPS made it possible for this new generation of airplanes to use its inherent range capabilities to reshape the North Atlantic market.
Boeing data as of December 31, 1997, show that on average, an engine failure in the ETOPS portion of the flight causes one diversion to an ETOPS en route alternate for every 70,000 flights.
Though the focus on en route alternate airports is primarily for twinjets, these airports are important for the safety of all long-range operations regardless of the number of engines. A sufficient number of these airports must be available to support unscheduled landings due to such emergencies as cargo fire, decompression, fuel leak, passenger illness, or severe turbulence. Boeing data show that on several occasions, 747s and DC-10s have diverted to various islands in the Pacific, namely Adak, Midway, Shemya, and Wake. Reasons for these diversions included passenger or crew medical emergency, an unanticipated headwind requiring additional fuel, and a 747 diversion to Wake for an engine fire warning.
ETOPS rules require operators to ensure availability of en route alternate airports. However, data collected worldwide (figure 3) show that a four-engine airplane has as much, if not greater, need for diversion to such airports for engine-related causes. Ensuring the availability of en route alternates is a sound operational practice for all airplanes.
The North Pacific has several en route alternate airports (figure 4) that meet the ETOPS requirements for air traffic control, approach navigational aids, emergency services, runway load-bearing capacity and length, and weather reporting to successfully plan ETOPS flights. Boeing data indicate that most of these airports meet the requirements to support a wide variety of airplanes, including the 777.
Depending on the type of airframe/engine combination and the ETOPS single-engine speed, operations under 180-min ETOPS may be possible between the United States and Japan just using Anchorage, Alaska, in the United States, and Kushiro, Japan, as ETOPS en route alternates. However, for some airframe/engine combinations and the single-engine speed selected, one more en route alternate may be needed between Anchorage and Kushiro to operate under 180-min ETOPS or provide additional flexibility in routing (figure 5).
Prior to dispatch of an ETOPS flight, operators must ensure that the weather at the selected alternate airport meets the ETOPS weather minimums (a certain level of ceiling and visibility minimums). Boeing studied the weather data from 1985 through 1994 at alternate airports such as Magadan, Petropavlovsk, in Russia, and several airports in Alaska. Results of the study showed the probability of simultaneous airport closure as almost zero. The analysis showed that at least one airport will always be available between Anchorage and Kushiro. Several other adequate airports for ETOPS exist in the mid-Pacific, including Guam, Majuro, Midway, Saipan, and Wake. Data indicate that these airports will be available as en route alternates for the foreseeable future. These airports can be used as en route alternates for both North and Mid-Pacific operations. Operators and pilots in command will gain additional flexibility if the FAA and Joint Aviation Authorities approve a 15 percent operational extension of the current 180-min rule, as discussed in "Anticipated ETOPS Developments."
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