On July 20, Emirates flight 242 from Toronto to Dubai by A380 returned to its point of departure after two hours of flight following the failure of one of its four engines. If this wise decision was taken because the incident took place at the very beginning of the flight, the aircraft could just as well have continued with 3 engines until its final destination if the event had happened much later.
Similarly, on August 22, a B737-800 of SmartWings, a Czech low-cost airline, flew 2h30 on a single engine before reaching its destination.
Indeed, today’s aircraft are designed to fly on a single engine if necessary. The question is how long!
The 60-minutes rule
Originally there was a rule in force: following a rule issued in 1953 by the FAA (Federal Aviation Administration in the USA) an aircraft could not be more than 60 minutes flight from a landing field. Not much of a problem when flying over a continent, much more annoying when flying over oceans.
This is why three-engine aircraft such as the Boeing 727, the Lockheed L-1011 TriStar and the McDonnell Douglas DC-10 were developed and, of course, a four-engine aircraft, the Boeing 747, was created to allow direct transatlantic flights. Indeed twin-engine aircraft, limited by the 60-minute rule (to be more precise, 60 minutes in the USA and 90 minutes in other countries applying ICAO rules), had to use less direct trajectories to stay close to the coast which lengthened the duration of the flight and thus increased the consumption.
But as time went by, the engines became more reliable and it became possible to give a little more leeway to the twin-engines. This is the birth of ETOPS certification.
ETOPS ?
The FAA and ICAO (International Civil Aviation Organization) worked on a new regulation taking into account the performance of the latest generation of aircraft. This is the ETOPS certification for Extended-range Twin-engine Operation Performance Standards.
Starting in 1989, some aircraft received the ETOPS 120 approval, meaning that they were authorized to be within 120 minutes (2 hours) of a diversion airport: at Airbus, the A300-600, A310, A320, A330, and at Boeing, the 757, 767 and some 737. This marked the end of the career of the McDonnell Douglas MD-11 and even dealt a blow to the sales of the Boeing 747.
In 2009 appeared the ETOPS 180 qualification (able to fly 3h on a single engine). Today we also find ETOPS 240 (A330), ETOPS 330 (B777, B787), ETOPS 370 (A350 XWB), and soon ETOPS 420 (A350 XWB)!
You read correctly, an A350 can fly more than 6 hours (soon 7) on a single engine! At this pace, we’ll soon be able to cross the Atlantic in a single engine!
And while “T” in ETOPS stands for “Twin Engine,” since 2015 ETOPS has also been mandatory for quadjets if they are to fly within 180 min of a landing zone. The B747-8 has thus received ETOPS 330 qualification.
How is the ETOPS qualification obtained?
Don’t worry, it is not enough for a manufacturer to claim that his aircraft can last 4 hours on a single engine for it to be authorized to fly directly over the Atlantic without any possibility of diversion! It is a long and very controlled process that includes several steps.
First of all, ETOPS qualification is not given to a family of aircraft (the A330s for example) but to each aircraft individually. Some airlines do not qualify all aircraft that could be qualified because they do not intend to use them on routes that require it.
The process begins with a type approval (the aircraft and engines meet a certain number of criteria and tests in real conditions are carried out), then operator approval (the airline has set up a certain number of procedures according to its national legislation, the pilots are trained) and finally a verification flight for each aircraft.
ETOPS and the A380
There are many reasons for the commercial failure of the A380 and ETOPS is one of them. When it was designed and when it made its first flight (2005) the maximum ETOPS qualification was ETOPS 180 (3h maximum from a diversion airport), which justified the existence of quadjets. In 2007 this limit was removed, opening the way for ETOPS 240, 370 etc.
This relaxation of the operating constraints of twin-engine aircraft made them very competitive compared to a four-engine aircraft that was more expensive to operate but which had the advantage of being able to take the most direct routes. With the loss of this advantage, we have witnessed the programmed end of the quad-jets.
What ETOPS does not mean
When direct flights over the oceans in twin-engine aircraft began, with increasing distance from the coast, not everyone was necessarily reassured, assuming that it was better to lose an engine on a four-engine aircraft than on a twin-engine aircraft.
This gave birth to this translation of the acronym: Engine Turning Or Passenger Swimming. A little joke not to be told to fearful passengers.
Do you know the Gimli glider?
This is one of the most famous engine loss stories in the history of aviation. On July 23, 1983, Air Canada Flight 143, a B767 flight from Montreal to Edmonton, ran out of fuel in mid-air. The pilot managed to glide the aircraft to Gimli, a disused airbase where he managed to land it.
The reason for this failure? A metric system problem. The pilots asked for the required fuel weight in kilograms and the airport staff thought it was pounds (Canada had just switched to the metric system).
If you have some time, the whole story is told in this video.
Photo : engine failure de hbpro via Shutterstock
