Posts: 438
Joined: Mon May 24, 1999 11:24 am


Tue Jun 08, 1999 1:57 pm

I know what ETOPS stands for and what the basic meaning is, but who certifies the twin engine planes and what are the stipulations for the aircraft to pass. Does it have something to do with how long the aircraft can fly under the power of one engine?

RE: Etops?

Tue Jun 08, 1999 2:08 pm

To my knowledge, to fly ETOPS you must be within 90 minutes of a suitable airport at all times when operating on one engine. The FAA and other international regulating bodies do the certifying.
Posts: 955
Joined: Tue May 18, 1999 2:59 am

RE: Etops?

Tue Jun 08, 1999 3:21 pm

If a plane has an etops rating of "120 minutes" that means it has to fly a route that never takes it over 120 minutes' flying time away from an airport if it loses an engine. Other planes have longer allowances. I think the longest being done now is by the 777, and it is 210 minutes on routes over the Pacific. Boeing is urging the industry to abandon the ETOPS rules. AW&ST magazine said that only one in every 60,000 ETOPS flights ever has engine problems, and none has ever crashed due to losing both engines. The rules were made back when the A300 and 767 began to fly the Atlantic, and nobody really trusted the two-engined planes over the ocean. In the 15+ years since we started using the twins, they've proven their safety. Now the 767 is the most-flown aircraft across the Atlantic and the 777 is used every day to cross the Pacific. Modern engines have proven their reliability, and (in my opinion) ETOPS really isn't needed anymore.
Posts: 109
Joined: Sun Apr 03, 2011 5:15 pm

RE: Etops?

Tue Jun 08, 1999 5:17 pm

See the previous post on etops for the certification answer. It would save alot of time. It is up to the company of manufacture to prove to the civil aviation authority of its government. That a particular aircraft is capable of an etops flight. As the airarft builds up trouble free hours in flight, it is possible for the manufacturer to take the steps up the etops ladder. ie 90 120 180mins etc. As for scraping etops rules, why do you think there havnt been many accidents / incidents on etops flights. It proves to me that they work. They do need a wee bit of fine tuning and time will see to that. There is alot more to etops rules than just drawing a circle around an airport and making it fit. For example, etops rules state the MEL's an etops flight may dispatch with and states what the minimum requirments for an en-route airport are. rgds mr EtOpS
Posts: 3612
Joined: Mon May 31, 1999 4:44 am

RE: Etops?

Wed Jun 09, 1999 3:11 am

The FAA has just extended ETOPS to 207 minutes. This seems to be a protectionist measure for Boeing and 777 users.
Airlines operating the 777 will be able to reroute crossings along the Pacific and save money from that.
Bad news for Airbus and the A340 and A3XX.

Luis, Faro, Portugal
Posts: 1962
Joined: Tue May 18, 1999 8:32 am

RE: Etops?

Wed Jun 09, 1999 9:07 am

I'm still not clear on this issue. If a plane, say, is rated at 120 minutes ETOPS, does that mean that it can never be at a point from a suitable landing area which is more than the distance that it will be able to fly in 120 minutes under the power of one engine? Do they calculate that distance at the reduced speed of one engine and do they factor in the cruising altitude and the glide ratio? Also, will a twin-engined airliner not stay airborne on one engine alone? It certainly could not stay at the same speed or altitude with one engine out, but does the ETOPS rating imply that after the, say, 120 minutes has elapsed, the airplane will be in the drink and, therefore, must have already reached its emergency landing strip? Can a twin-engined airliner not stay airborne indefinately on one engine at a decent altitude as long as the fuel lasts or does ETOPS really mean
"Engines Turn Or Passengers Swim"?
An optimist robs himself of the joy of being pleasantly surprised
Posts: 109
Joined: Sun Apr 03, 2011 5:15 pm

RE: Etops?

Wed Jun 09, 1999 12:21 pm

Firstly RE 777 etops, Remember this will apply only to U.S. reistered 777's with the engine/airframe combination specified. That dosnt mean they cant certifiy every combination , nor does it mean that the CAA cant apply the rule. RE 120 ETOPS: First point to note is that on an etops plan, your not really flying etops until you reach the point that is 120 mins away from your destination. The 120 min rule is based on a 1 engine out situation. It is allways based on still air, ie it dosnt take any wind component into account. But it allways takes the worst case into account: For a 767 that is One engine out and depressurised at the Equi Time Point. ( or ETP1D ). The Equi time point is the point that is equal time to return to your last airport or go on to the next one. Because its a depress calculation, no credit is given for drift down from altitude. It is assumed that you will descend to about 10000 - 14000'. The ETPD1 speed is set by the company and appoved by the FAA/CAA etc. A good figure might be 317kts. So a 767 will do this at about 317kts and divert to the most suitable ALT airfield. The nominated speed is based on the chances of the remaining engine giving up and is a trade off between speed, fuel consumption and engine wear. In theory an aircraft could spin round on one engine until the fuel was exhuasted, but apart from being dumb it would run the chance of killing the remaining engine. This examplr was for the 767. Each aircraft is different. For example the 737 worst case is not depress, because it cant maintain alt economically anyway. Hope this hasnt been confusing. Rgds mr EtOpS

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