What Does It Mean When an Aircraft is ETOPS Rated

While soaring on a 14-hour flight between two cities aboard a Boeing 777-300ER, you suddenly notice that the plane has only two engines, as opposed to the four engines on a Boeing 747-400 that we’ve grown accustomed to. This realization might make you wonder what would happen if one engine fails, leaving only one engine to rely on while flying over the ocean at 40,000 feet. However, there’s no need to worry, as the plane is ETOPS rated, meaning it can still fly to the nearest airport for a safe landing. So, what exactly does it mean for an aircraft to be ETOPS rated, like the Boeing 777-300ER and the A350-900? Let’s dive into the details.

So what is ETOPS? ETOPS stands for Extended-range Twin-engine Operations Performance Standards. This special set of flight rules is specifically designed for situations where an aircraft is operating with only one functioning engine. The International Civil Aviation Organization (ICAO) developed ETOPS to govern the operation of twin-engine aircraft in airspace that is more than an hour away from a diversion airport at the one-engine-inoperative cruise speed. This can include flying over water, remote lands, or on routes that were previously limited to three- and four-engine aircraft. These rules ensure that even if an aircraft encounters engine trouble, it can still safely reach its destination or an alternate landing location.

The Reliability of Modern Jet Engines

At the core of the ETOPS approach is the understanding that modern jet engines are inherently reliable components. While engine ancillaries have a lower reliability rating, ETOPS-certified engines often feature duplicate sets of these ancillaries to achieve the required level of dependability. This focus on reliability enables twin-engine aircraft to operate on extended routes with a high degree of safety and confidence.

ETOPS Certification Process

The ETOPS approval process is two-fold. First, the airframe and engine combination must satisfy the basic ETOPS requirements during type certification, known as “ETOPS type approval.” This may involve rigorous tests, such as shutting down an engine mid-flight and continuing the flight using the remaining engine for the entire diversion time. It must be demonstrated that the flight crew can manage the lost engine without being overburdened and that the probability of the remaining engine failing is extremely remote.

Second, to obtain “ETOPS operational certification,” an operator must satisfy their country’s aviation regulators regarding their ability to conduct ETOPS flights. This involves compliance with special engineering and flight crew procedures in addition to standard practices. Pilots and engineering staff must be qualified and trained for ETOPS, and airlines with extensive long-distance flight experience may be awarded ETOPS operational approval immediately.

Regulatory Oversight

Regulators closely monitor the ETOPS performance of both type certificate holders and affiliated airlines. Technical incidents during ETOPS flights must be recorded and analyzed to measure the reliability of specific airframe-engine combinations. The required reliability figures for ETOPS-180, for example, are more stringent than those for ETOPS-120. Unsatisfactory performance could lead to downgrades or suspensions of ETOPS capabilities for the type certificate holder or airline.

Impact on Air Travel

The widespread adoption of ETOPS has revolutionized air travel, enabling airlines to operate more direct, fuel-efficient routes with twin-engine aircraft. These aircraft, such as the Boeing 787 Dreamliner and the Airbus A350, have become the backbone of long-haul operations for many carriers, reducing the need for larger, less-efficient four-engine aircraft.

Notably, ETOPS has allowed airlines to operate “long and thin” transatlantic routes with smaller aircraft like the Boeing 757, connecting major hubs with secondary European cities that cannot generate the passenger demand to justify the use of a wide-body airliner.

How ETOPS Came About?

In 1919, John Alcock and Arthur Brown made history by completing the first non-stop transatlantic flight in a twin-engine Vickers Vimy. They flew from Newfoundland to Ireland in just sixteen hours. By 1936, the Bureau of Air Commerce (now known as the FAA) imposed restrictions on aircraft operations, limiting them to within 100 miles of an airport. This distance was equivalent to roughly 60 minutes of flying time with one engine inoperative.

The 1950s saw the introduction of the FAA’s “60-minute rule,” which restricted twin-engine aircraft to a 60-minute diversion area. This rule was based on the piston engine reliability of the time, but there was some flexibility for special approval to fly beyond this limit. Around the same time, the International Civil Aviation Organization (ICAO) recommended a 90-minute diversion time for all aircraft, which was adopted by many regulatory authorities and airlines outside the US.

During this era, twin-piston aircraft flew long routes over the Caribbean and other remote areas. For example, Pan Am’s Convair 240s connected Barranquilla, Colombia, to Kingston, Jamaica, while KLM Royal Dutch Airlines operated Douglas DC-3s and Convairs on various routes across the Caribbean. Meanwhile, New Zealand National scheduled a DC-3 to fly from Apia, Western Samoa, to Aitutaki, covering over 680 miles without airports.

ETOPS has undeniably transformed the landscape of air travel, enabling airlines to operate more efficient and environmentally friendly long-haul flights. With the continued advancement of aircraft technology and increasing emphasis on sustainability, the impact of ETOPS on the aviation industry is only set to grow in the coming years.