What is ETOPS ?
ETOPS (Extended-range Twin-engine Operational Performance Standards) refers to the standards and recommended practices (SARPS) issued by ICAO for aircrafts that fly routes along which the aircraft would be more than 60 minutes from an emergency or a diversion airport at some points. The 60 minutes flight time is taken for one engine inoperative cruise speed in still air and the ETOPS portion of a flight begins the first moment an aircraft is greater than one hour flying time from the nearest adequate airport, and ends the last moment it is greater than one hour from the nearest adequate airport (UK CAA,2003).
Brief overview of ETOPS
Modern turbofan engines have made it possible to extend the range of twin-engined aeroplanes to allow some of them to fly great distances.However, the availability of suitable airfields where a landing can be made in the event of an emergency must be taken into account when planning flights over such distances. Because of problems associated with problems associated with the loss of a power unit or certain major systems on twin-engined aircraft, aviation authorities such as FAA and ICAO set a limit on the maximum distance a twin may be from an adequate aerodrome without special requirements being imposed. ICAO stated this limit to be 1 hour flight time, whilst cruising with 1 engine inoperative in still air.
This it was difficult for twin engine airplanes to be used over long distances, even though twin engine aircrafts would to be cheaper and more efficient to operate compared to 3 or 4 engine planes.
However, after advancements in turbofan engine technology, spearheaded by the A300, prompted FAA and ICAO to change the rules, and in 1985, ICAO and FAA issued guidelines for extended range operations for twin engine planes. The FAA promulgated conditions that need to be fulfilled for a grant of a 120 minutes diversion period i.e. the aircraft can be 2 hours from an alternate airport , which is sufficient for direct transatlantic flights, and other aviation authorities worldwide followed. ETOPS ratings are also granted for 180 minute and 240 minute diversion periods. ETOPS-180 is only possible after 1 year of trouble-free 120-minute ETOPS experience.
The following images show how the range for twin engine planes has extended because of ETOPS. The white regions indicate the areas twin engine planes can travel into, whilst the blue region indicates the areas the aircrafts cannot go into by law. It can be seen that the higher the ETOPS regulation applicability for an aircraft is, the further it can fly without facing alternate and diversion based restrictions. The source for these images is a publication issued by boeing in October 2003 entitled ETOPS, Extended Operations, and En Route Alternate Airports written by Brad Bachtel. The URL for this publication is Here
Requirement for ETOPS certification
Thus, if an operator intends to fly extended range operations, it must be ETOPS certified. That being said, private jets are exempt from ETOPS by the FAA, but they must satisfy JAA ETOPS 120 requirements for extended range flights.
ETOPS regulations vary from region to region, but in general, both the aircraft and the aircraft operator need to be certified in order to arry out ETOPS.
In the case of FAA, airplane certification guidance for ETOPS can be found in 14 CFR 121.162 and 25.1535. As with all other operations, a certificate holder requesting any route approval must show that it is able to satisfactorily conduct operations between each required airport as defined for that route or route segment, and any required en route alternate airport. Certificate holders must show that the facilities and services specified in 14 CFR 121.97 through 121.107 (domestic and flag operations) and 14 CFR 121.113 through 121.127 (supplemental and commercial operations) are available and adequate for the proposed operation. In addition, the certificate holder must be approved for ETOPS under part 121.
In the case of the UK CAA, the requirements for ETOPScertification are given in CAP 513 : Extended Range Twin Operations (ETOPS). This section considers type design factors, operator experience, engine reliability and propulsion system reliability assessments, maintainance requirements and other operational limitations.
In general, all aviation regulations are in accordance with ICAO Volume 2, Air operator administration, Ch. 3 Extended-range operations with 2 engine aircrafts.
Safety and ETOPS
The current approval standard for 180-minute ETOPS is 0.02 shutdowns per 1,000 hours of engine operation. That’s amounts to an in-flight shutdown rate of one every 50,000 hours. Many of the world’s 92 ETOPS operators are achieving 0.01 shutdowns per 1,000 hours or, for twinjets on eight-hour ETOPS flights (accumulating 16 hours of total engine time per flight), an average IFSD of one every 6,200 flights. This level of demonstrated safety has prompted many operators and authorites to opt for longer planned diversion times, from 240 minutes to virtually "unrestricted" ETOPS. Statistically, twin engine planes have a lower likelyhood of a diversion compared to 3 or four engine planes.
However, the lack of sufficient redundancy in the case of a twin engine failure is a concern for ETOPS operations. Also, extending ETOPS durations may compromise the safety of a flight, since an adequate safety margin should be ensured to make sure the plane can land at the nearest airport in the case of an emergency.
Also, the effect of vast improvements in technology must will mean that crew members on an ETOPS aircraft will have to be trained to deal with emergencies in a more stringent way, which would in turn increase their work load.
Want to know more?
- An overview of ETOPS