ETOPS Questions

t0r0nad0

t0r0nad0

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PJ Gustafson
So my boss was watching the United 777 DVD that he got for his son and he mentioned that the captain was explaining the concept of ETOPS. I know that it means Extended Twin OPerationS (or "Engines Turn Or Passengers Swim") and in plain English, a twin-engined aircraft must be within xxx minutes of an airport suitable for landing any time it goes overseas, just in case they were to lose an engine. The boss said that the United captain explained that with the 777, they had to be within 128 mins of an airport at engine-out cruise speeds. Now, I can see how this would be possible for Atlantic crossings and northern Pacific crossings, as they typically arc up over the very northern reaches of the ocean where there tends to be more land. The questions are, what if you're going to Hawaii, which is 2300nm from the West coast of the US? Is the halfway point within that ETOPS window? Am I misunderstanding something?
 
I think it also has something to do with the probability that an engine will fail.
 
The 777 was approved for 180 minute ETOPS (it was in Boeing's contract with United), and i'd be surprised that United wouldn't have 180 min (or even 207 minutes) ETOPS approval. Each operator gets individually approved for ETOPS by the FAA, with a defined set of approved airplanes, crew, and operating area(s). I think maybe you're boss didn't hear 128 minutes, or the 128 minutes he heard was a different limitation (perhaps extra fuel required?).

So, to make it really outrageously simplified, since the 777 cruises at .78M or higher (maybe 440+ KTAS), 2300 NM is less than six hours away, and well within 180 Min ETOPS standards. Some operators use 737s for that route as well.

Also, ETOPS no longer means "Extended Twin engine OPS". In the new FAA speak, it means "ExTended OPS", and applies to all multis, even those with three or more engines.

An interesting article can be found at: http://www.flightsafety.org/asw/mar07/asw_mar07_p12-16.pdf
 
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Here is a link to a great circle mapper. http://gc.kls2.com/

Put in two airport pairs, such as SFO - HNL for San Fran to Honolulu. The web page will plot the GC route. Notice on the right you can also check etops times. This will produce shaded circles or circle segments showing the ETOPS range on the map.

This documents an etops gap on the sfo - hnl route. If you look in the documentation, you will note that the etops mapper uses 389 kts for airspeed, which they say is appropriate for a 757 and not that far off for other planes.

-Skip
 
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We can go up to 207 minutes in the Pacific. The higher you get, the more restrictions there are as far as weather requirements and equipment goes. The breakdowns are 120 138, 180 and 207. Maybe 150 too, but I don't recall ever seeing that one.
 
How did they come up with 207? Not 200 or 210, but 207.
 
It makes sense to a point. I still wonder how they came up with 45 min reserve fuel for night VFR or day/night IFR. It would have made more sense to me to require a flat 60 minutes. I can only imagine the rule was established at a time when flights were much lower and distance flown was much shorter for the average hop.
 
Isn't ICAO really skeptical/generally does not accept the + 15% routes?

~ Christopher
 
Oh, one other thing.. I was reading in this month's "Airways" magazine of a trip across the Himalayas in an Airbus twin, operated under ETOPS rules even though it was overland - all due to the incredible distances between suitable airports.
 
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