ETOPS

Whats ETOPS?

Of course everyone knows Extended-range Twin-engine Operation Performance Standards

But what does that means? and Why ETOPS?

Before I explain, lets look into aircraft development briefly.

Since the First flight by the Wright Brothers, Piston engine propel the aviation development, and started the era of powered flight. Aircraft developer has been trying to increase the power output out from the piston engine.

(Especially during the war era)

In order to increase aircraft performance, the power output of piston engine; the most direct method by increase the cylinder displacement volume and compression ratio; however, that also affect the reliability of the engine.

Engines are so unreliable in the early aviation development. Engine failure rate is relatively high and aircraft is consider not as reliable.

Aviation Regulator requires Twin engine operators to remains within 60 minutes flying time of an airport that is adequate for landing in the event of an emergency. FAR 121.161

In other word, since the aircraft considered not as reliable; operators with 2 engines needs to stay close to alternates, which alternate airports is available for diversion.

By taking the 60 mins route, aircraft are require to fly over longer track; which take more time and consume more fuel. However, aircraft with more than 2 engines was not restricted under this regulation; and became one of the success factor for 4 engine aircraft (B747).

Since 1950s, turbine engine introduce to airline industry, aircraft reliability has vastly improved. (Brayton cycle can increase engine power output without scarifying reliability.)

As engine and aircraft technology evolves, aircraft becomes more reliable and efficient. Airline initiate researches to look into more direct routing in order to reduce traveling time and operating cost, while maintaining a high safety level.

Engine failure rate of 0.35 per 1000 engine hours in 1953; compare to figures in 2019 is 0.02 or less per 1000 engine hours. Air travel is consider the safest mean of transportation.

In 1985, responding to the industry's desire to take advantage of the increased reliability and capabilities of two-engine airplanes, the FAA issued AC 120-42. It grants operation to 120 mins. With the advantage of 120 mins ops, aircraft is allowed to operate a more direct route.

As technology further advance, Industry has Stepped Up to Higher Standards; and ETOPS approval grant from 120 mins to 180 mins. The A350XWB offers 370min ETOPS; with that range, the A350 can almost reach anywhere in the world with direct routing.

ETOPS

Extended Twin-engine Operations; allow operation to fly beyond the 60-mins area from the alternate.

ETOPS vs EDTO

ETOPS is a FAA terms and more focus on Twin engine aircraft; and EDTO (Extended Diversion Time Operations) is an ICAO term, similar idea to ETOPS. Compare to ETOPS, EDTO not only applicable to Twin engine aircraft; but also aircraft with 2 or more engines.

If interested, click here to have a good read on this ICAO doc.

EDTO Certification

In order to operate EDTO, the aircraft type being used has to be EDTO Certified. Per ICAO requirement, the aircraft manufacturer must perform an assessment of the aircraft design to identify confirm the capability of relevant Time Limited System.

(Question to you, Which system defines the applicable limitation for EDTO? Comment below)

As mentioned before, A350 offers 370mins ETOPS; that means during the aircraft type certification, Airbus submitted documents to satisfy ICAO/FAA/EASA requirement, and proved the aircraft is very reliable and safe. And FAA granted ´beyond 180 minutes’ diversion time Extended Operations (ETOPS) for the Airbus A350 family aircraft.

"Beyond 180 mins" includes a basic 180-minute ETOPS, also includes provisions for 300 minutes—corresponding to a 2,000 nautical miles (3,704km.) maximum diversion with a single engine inoperative “under standard atmospheric conditions.”

So, if I got an awesome aircraft, I can fly EDTO?

Not exactly!

Besides the Aircraft Certification, the operator needs have approval from the National Aviation Authority. In order for the authority to grant an operator for EDTO, it will carry out assessments to the operation and maintenance(also training.)

Once the authority is satisfied with the performance, airline will be granted approval to operate beyond 60 mins range. And the authority will continuous monitor the operators performance for additional approval or downgrading.

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Lets complete this unfinished business~

Previously, we talk about the EDTO Certification.

Regulatory authorities(FAA, EASA..) continuously evaluate the reliability of the EDTO operation. That's also why airline/ manufacturer so conscience about In-flight shutdown (IFSD) rate, it will affect the reliability of the engine and aircraft; thus, limit the EDTO rating.

For those interested to know more, look into the certification process of the 787.

787 has the Trent 1000 engine; and it has been Rolls Royce headache since it roll out.

Lets talk about some operation aspect about EDTO flights.

First of all, EDTO flight starts with planning. Lots of people has a misunderstanding of the idea of the range of operation