According to this press release by Boeing earlier this year, the 747-8 has received its ETOPS 330 rating. This is required by all 4-engined planes made after February 2015 to fly beyond 180 minutes from an en-route alternate airport.

Does this apply only when one engine has already failed? I understand four-engine jets usually continue to their destination on three engines. And how does this compare to the 747-400. Can it fly ETOPS 330+ routes? I remember them doing missions that twin-engine aircraft couldn't because of their lack of ETOPS.

A follow-up question for those who are interested: Why does ETOPS not apply to older 4 engine aircraft?

  • 3
    $\begingroup$ There is something wrong if Extended Twin Ops (or Extended-range Twin-engine Operational Performance Standards if you wish) are forced on four-engined planes. $\endgroup$
    – Monolo
    Commented Jun 12, 2015 at 10:27
  • 2
    $\begingroup$ ETOPS = Extended Range OPerationS $\endgroup$
    – Peter
    Commented Jun 12, 2015 at 15:07
  • 4
    $\begingroup$ 330 min is good enough to cover the entire Earth except for an area of Antarctica and ocean south an area between Africa and Australia (see [gcmap.com/mapui?MS=bm&PW=2&DU=mi&E=330](map)). For any practical purpose, 330 is enough to go anywhere you'd like to go. $\endgroup$ Commented Jun 13, 2015 at 0:36
  • 2
    $\begingroup$ @Monolo -- ETOPS nowadays is basically a catchall for all the things required to fly over an area with no diversion options nearby. $\endgroup$ Commented Jun 14, 2015 at 1:13
  • 2
    $\begingroup$ @paul Yes and No, it's ambiguous!? I'm not a pilot! I refer to the old use of EROPS ("Extended range operations"), till mid 1980s. And the old usage of ETOPS ("Extended Range Operations with two-engine airplanes") till 2007. Airbus suggessted LROPS ("Long Range Operations", especially for three- and four-engine to avoid confusion, particularly for those operations beyond 180-minutes diversion time. Finally the FAA decided to stay with ETOPS but use it for every plan, so it's current official meaning is "Extended operations" (no mention of "twin"). $\endgroup$
    – Peter
    Commented Jun 15, 2015 at 9:58

5 Answers 5


ETOPS stands for Extended-range Twin-engine Operational Performance Standards, a rule which permits twin engine aircrafts to fly routes which, at some point, is more than 60 minutes flying time away from the nearest airport suitable for emergency landing. ETOPS may also be interpreted as Engines Turn or Passengers Swim.

It is not a rule which applies after an engine has failed. Rather, it is a set of regulations and standards which must be met if an airliner wishes to fly its planes more than 60 minutes away from a suitable emergency airport.


Early combustion engines were noticeably unreliable. It was not uncommon for a 4-engine piston aircraft to arrive at its destination with only 3 engines running. Twin engine aircrafts, as a result, were required to fly dogleg paths to stay close enough to an adequate airport.

Aircrafts with more than 2 engines were not restricted by this rule. Thus, many transatlantic flights were flown with Boeing 747s and L-1011s, since airliners can fly a more direct route with these aircrafts.

As engineers gained more experience in jets, they slowly recognized that jet engines are much more reliable than their piston counterparts. The FAA began to approve flying twin engines 120 minutes away from a suitable airport. This made twin engine aircrafts popular, because the fuel efficiency of flying a twin is much better than flying a 4-engine 747 or A340.


ETOPS certification requires both the aircraft and the airline to comply with a set of standards.

For the aircraft, the manufacturer must demonstrate that flying with only one engine is relatively easy for the flight crew, safe for the airframe, and an extremely remote event.

The airline must demonstrate that its flight crew training and maintenance procedures are up to a higher standard. Pilots, engineers and staff must be specially qualified for ETOPS.

Recently, more operators are adopting the ETOPS approach to non-ETOPs routes. They discovered that the approach offers significant improvements in reliability, performance and dispatch rates. The cost of application is later offset by reduced maintenance costs, and costs associated with diversions, delays and turn backs.

Flight Plan

An ETOPS flight plan may look something like this:

enter image description here

Let's say the aircraft's ground speed (with one engine inoperative!) is 450 knots. By drawing circles with radius 450nm around alternate airports, we can obtain areas which the flight must stay within. The flight path always stays inside one of these circles. If we are operating under ETOPS 120, we will draw the circles at 900nm.

Actual flight plans are slightly more complex, since winds aloft (sometimes more than 100 knots) will affect the aircraft's ground speed. Dispatchers use software to calculate a route, taking aircraft weight, fuel consumption and winds into consideration.

  • $\begingroup$ Good answer. I would like to know why the 747-8 didn't get a higher ETOPS. And if the 747-400 can fly ETOPS 330+ routes. Maybe I should ask a new question about that. $\endgroup$
    – collector
    Commented Jun 14, 2015 at 8:57
  • 1
    $\begingroup$ So say an airline wanted to fly Cape Town - Auckland. It could do it with a 747-400 or A350, but not a 747-8? $\endgroup$
    – collector
    Commented Jun 14, 2015 at 10:09
  • 3
    $\begingroup$ I would suggest asking "why does ETOPS apply only to newly built 4 engines aircrafts" as a new question. $\endgroup$
    – kevin
    Commented Jun 14, 2015 at 10:14
  • 2
    $\begingroup$ Actually, this answer is based on the old rules. it now does apply to 3 and 4 engine aircraft, and has a new name which isn't restricted to twin engine aircraft. $\endgroup$
    – Lnafziger
    Commented Jun 15, 2015 at 13:14
  • 3
    $\begingroup$ This answer doesn't seem to address the fact that a 747 has four engines at all $\endgroup$ Commented Sep 16, 2016 at 18:58

I see no mention of 14CFR 121.161 so here it is.

§ 121.161 Airplane limitations: Type of route.

(a) Except as provided in paragraph (e) of this section, unless approved by the Administrator in accordance with Appendix P of this part and authorized in the certificate holder's operations specifications, no certificate holder may operate a turbine-engine-powered airplane over a route that contains a point—

(1) Farther than a flying time from an Adequate Airport (at a one-engine-inoperative cruise speed under standard conditions in still air) of 60 minutes for a two-engine airplane or 180 minutes for a passenger-carrying airplane with more than two engines;

(2) Within the North Polar Area; or

(3) Within the South Polar Area.

(b) Except as provided in paragraph (c) of this section, no certificate holder may operate a land airplane (other than a DC-3, C-46, CV-240, CV-340, CV-440, CV-580, CV-600, CV-640, or Martin 404) in an extended overwater operation unless it is certificated or approved as adequate for ditching under the ditching provisions ofpart 25 of this chapter.

(c) Until December 20, 2010, a certificate holder may operate, in an extended overwater operation, a nontransport category land airplane type certificated after December 31, 1964, that was not certificated or approved as adequate for ditching under the ditching provisions ofpart 25 of this chapter.

(d) Unless authorized by the Administrator based on the character of the terrain, the kind of operation, or the performance of the airplane to be used, no certificate holder may operate a reciprocating-engine-powered airplane over a route that contains a point farther than 60 minutes flying time (at a one-engine-inoperative cruise speed under standard conditions in still air) from an Adequate Airport.

(e) Operators of turbine-engine powered airplanes with more than two engines do not need to meet the requirements of paragraph (a)(1) of this section until February 15, 2008.

[Doc. No. 7329, 31 FR 13078, Oct. 8, 1966 as amended by Amdt. 121-162, 45 FR 46739, July 10, 1980; Amdt. 121-251, 60 FR 65927, Dec. 20, 1995; Amdt. 121-329, 72 FR 1879, Jan. 16, 2007]

  • $\begingroup$ Why the ditching-certification exemptions for all those old propliners? $\endgroup$
    – Vikki
    Commented Aug 15, 2019 at 0:13
  • 1
    $\begingroup$ Those exemptions went away 12/20/2010 and I suspect they had something to do with Alaska operations which is a whole other thing unto itself. $\endgroup$ Commented Aug 15, 2019 at 15:57

ETOPS does not only affect the engines of an aircraft – long ETOPS ratings such as the 747-8's 330-minute ETOPS capability also require that systems like fire suppression be sufficient for over five (!) hours of flying after something in the cargo hold sets itself ablaze. This is accomplished by metering a flow of extinguishing agent into the cargo hold after the initial "knockdown" shot to keep the fire in check until the plane can land.


Boeing has a post about it here: http://www.boeing.com/commercial/aeromagazine/articles/qtr_2_07/article_02_7.html

Basically, twins have to get ETOPS when they are more than 60 minutes from an airport, and planes with 3+ engines have to get it when they are more than 180 minutes from an airport.

Hopefully that answers your question.


Easy to remember like this:

Engines Turn Or Passngers Swim

Basically it is a rule governing all twin engine aircraft. Before there was the 777/787 - when twin engine aircraft were not capable of flying trans-atlantic or trans-pacific routes while still being within a 60 minute window of being able to perform an emergency landing at the nearest airport, twin engine aircraft were forbidden from making such flights. Now, a plane can be ETOPS certified to a very high standard, one which used to only be achieved by 3 or 4 engine aircraft. The standard is to prove the plane can fly over vast stretches of ocean and in the worst possible situation still be able to have enough range to land within 60 minutes without ditching in the water.

  • 1
    $\begingroup$ Welcome! that's correct, but doesn't add new elements to existing answers. $\endgroup$
    – mins
    Commented Sep 13, 2017 at 7:02
  • $\begingroup$ "have enough range to land within 60 minutes" - except ETOPS > 60 where the plane must be capable of flying for more than 60 minutes to make it to a diversion airport or its final destination. $\endgroup$
    – FreeMan
    Commented Sep 13, 2017 at 12:27

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .