ETOPS (Extended-range Twin-engine Operations, or simply Extended Operations) are a system of rules allowing twin-engine aircraft to fly routes passing further away from the nearest diversion airport than would otherwise be permissible.
In regular operations, a twin-engine aircraft must stay within 60 minutes' single-engine flying time of an airport suitable for an emergency landing. This makes certain places in the world (the blue parts of the following map) unreachable for a twin-engine aircraft:
(Image source: Boeing)
ETOPS (originally Extended-range Twin-engine Operations, now often simply Extended Operations, colloquially Engines Turn Or Passengers Swim) is a rule which permits twin-engine aircraft satisfying certain conditions to fly routes which, for part of their length, are more than 60 minutes' single-engine flying time away from the nearest airport suitable for an emergency landing. These are primarily long-distance overwater routes (hence the "or passengers swim"), but also include routes over areas of very-sparsely-populated land, such as much of Siberia and parts of the Sahara Desert and australia's Outback.
The conditions for an airline to benefit from ETOPS are related to the design, operation and maintenance of certain airplanes:
- The airframe and engine combination must satisfy ETOPS requirements during certification.
- The pilots and staff must be trained for ETOPS.
- Additional flight crew procedures and special engineering must be put in place by the aircraft operator.
ETOPS approvals are issued with a number denoting how far the aircraft is allowed to be from the nearest diversion airport; for instance, an aircraft with ETOPS-240 approval, such as the airbus-a330, is allowed to fly routes with segments as far as 240 minutes' single-engine flying time from the nearest diversion airport. The longest-range ETOPS currently in use is ETOPS-370, held by the airbus-a350, although airbus is shooting for ETOPS-420 (which would allow the A350 to fly as far as seven hours' single-engine flying time from the nearest diversion airport).
The first ETOPS flights (not yet referred to as such at the time) were ETOPS-90 flights made by the airbus-a300 starting in 1976. ETOPS-120 was introduced in 1985, followed by ETOPS-180 in 1988 (nowadays, these are often extended by 15%, to ETOPS-138 and ETOPS-207, respectively, to allow these routes to be flown even if one of the diversion airports is closed); ETOPS-240 (first used by the aforementioned A330) was introduced in 2007, ETOPS-330 in 2011 (although the first actual ETOPS-330 revenue flights, by the boeing-787 and select models of the boeing-777, did not begin until 2015), and ETOPS-370 in 2014.
