What is ETOPS and How is it Used by Airlines?

Aircraft · 4 min read · Dec 20, 2021

Many people question aircraft safety, and many others believe other forms of transportation can be safer, but history has proven they are all wrong. How is this possible? This is possible because aviation authorities have always taken safety very seriously, and they have done everything to ensure the safety of the crew and the passengers are 100% guaranteed. So, what does this have to do with ETOPS?

What is ETOPS?

ETOPS stands for Extended-range Twin-engine Operational Performance Standards. In other words, it refers to rules and regulations established for the operational performance of aircraft that had twin engines to guarantee safety. Here’s a little background for a better understanding.

How it all started

In the early days of aviation, aircraft used piston combustion engines that were not very reliable. More often than anyone could even imagine, this lack of reliability made some 4-engine aircraft fly and land with one of their engines out of order, a dangerous situation for the crew and the passengers.

Of course, having a twin-engine aircraft flying with one engine only was even worse. Therefore, two-engine aircraft were limited to flight paths that would keep them within the range of a suitable airport for an emergency landing. This was called the 60-minute rule.

A graph depicting a non-ETOPS flight path and an ETOPS flight path.
Image source: https://en.wikipedia.org/wiki/ETOPS

What is the 60-minute rule?

Although it was not officially called ETOPS, the 60-minute rule is considered the first ETOPS rule ever. It was created by the Federal Aviation Administration (FAA), and it restricted twin-engine aircraft to fly on a route that would keep it within a 60-minute flight time of an adequate airport or landing area in case of emergency.

However, this made the transatlantic flight a challenge since only a specific type of airplane could fly on these routes, and it was costly due to the amount of fuel required by 4-engine piston aircraft.

Fortunately, aviation designers eventually realized jet engines were stronger and more reliable for longer and faster service.

First twin-engine aircraft with ETOPS certification

By the time of the 60-minute rule, there was no real certification. It was more of a restriction imposed for flight planning and flight dispatch. In 1985, the first ETOPS rating was certified, permitting Trans World Airlines 767 twin-engine airliner to fly transatlantic routes from Boston to Paris, with a rating of 120 minutes. This rating meant that the flight route could be within a 120-diversion area.

What is the difference between ETOPS and EDTO?

The simple answer to this question would be saying that while ETOPS stands for Extended-range Twin-engine Operational Performance Standards, EDTO stands for Extended Diversion Time Operations. And this would be the main difference, of course. However, there are other relevant differences to mention.

Since the first commercial aircraft received an ETOPS rating, great advancements have been achieved in improving aircraft reliability and providing them extended range operations. These developments eventually forced many regulatory authorities to review ETOPS rules.

Rules revised

The result was the introduction of changes to ICAO Annex 6 Part 1 under Amendment 36 in 2012, which included the EDTO regime in place of ETOPS. However, the acronym was never embraced, and ETOPS was kept as the acronym used to refer to the new rules.

Another relevant aspect is that using the acronym ETOPS is not very accurate when referring to the EDTO regime. Another difference between EDTO and ETOPS approach is that EDTO covers extended range operation of aircraft with more than two turbine engines, such as those with three and four engines.

Finally, one more relevant aspect is the maximum diversion time allowed under EDTO. With ETOPS, some records say some aircraft have gotten ratings up to 370, like the Airbus 350, for example. Actually, some rumors suggest Airbus was seeking a rating of 420 in 2014, but nothing has been confirmed. However, according to EDTO, the maximum diversion time must be 180 minutes, based on ICAO guidance.

An ETOPS certified aircraft flying a transatlantic route from Europe to an island in the Caribbean sea.

Who needs ETOPS operational approval?

In general, ETOPS certifications are primarily given to aircraft manufacturers. However, certain aspects of ETOPS rules refer to airlines’ operations, which is why they also need to go through the approval process.

What is required for ETOPS ratings?

As mentioned in the previous point, both aircraft manufacturers and airlines need to get an ETOPS certification rating to fly on ETOPS routes. Therefore, there are specific requirements regarding the aircraft and others specifically for the airline’s operations. Let’s take a look at each of them separately.

Aircraft manufacturer requirements

Here’s a list of the main requirements for aircraft manufacturers to obtain certification.

  • Demonstrating that any crew can manage flying the aircraft with one engine in a relatively safe manner.
  • Demonstrating that flying with only an engine is safe for the airframe.
  • Demonstrating that having an engine inoperative is an extremely rare occurrence.

Flight crew and airlines’ operations requirements

Here’s a list of the main requirements for an airline’s crew and other areas of operation to obtain certification.

  • High standards are applied to training and maintenance procedures.
  • Pilots, engineers, and aircraft dispatchers must be certified accordingly.

Do aircraft with more than two engines require ETOPS?

Whether the answer to this question should be positive or negative is actually a matter of semantics. If you remember the difference between ETOPS and EDTO, we could say that the answer is a no since these rules are specific to aircraft with two engines while EDTO covers the rest. But, remember that ETOS is also used to speak about EDTO, so in this case, anyone could argue that aircraft with three engines or more require ETOPS.

The truth is that more and more airlines are embracing ETOPS and working closely with aircraft manufacturers because airplanes with fewer engines and with better engine reliability result in reduced maintenance costs, making them more profitable than they can be when flying non-ETOPS routes in the long run.

The highest ETOPS certification Boeing 777-300ER taking off from a runway.
Image source: JacobAviation

Summary of the ETOPS

Now you know how important safety is for the aviation industry. Next time you fly, you can rest assured that there should not be any problem, and even with a failed engine, your pilot should be able to take you safely to the ground at the nearest airport available.

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Jet pilot @NASA

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