Engine Failure

ENGINE FAILURE

Question:  As a GA (General Aviation) pilot myself, your questions and answers are wonderful.   My question is regarding a recent incident in which an American B-777 lost an engine while flying from Los Angeles to London, but landed safely at JFK less than 30 minutes after the engine failed.  I know aircraft are certified to fly with less than a full complement of engines working.  However, what would have occurred if this aircraft were halfway across the Atlantic/Pacific/Arctic?  I assume the flight would continue to the closest airport, but on such a long flight would there be problems?  Thanks.
Dwayne Trammell, Atlanta, GA

Answer:   Twin engine aircraft such as the B-777, B-767, A-330, etc., when flying long-haul routes over water or over long expanses of unpopulated areas, fall under regulations known as International Twin-Engine Operations or ETOPS (pronounced "ee-tops").   When aircraft fly over land, they're required to have an enroute alternate destination no more than 60 minutes away at all times.  This is not possible on long flights over water or over large expanses of unpopulated areas, however, and as more reliable engines were developed, the need for a different set of rules became apparent so twin engine aircraft could fly longer routes without the constraint of the 60 minute diversion rule.  ETOPS allows a longer flying time to an alternate, as much as 207 minutes.

Having flown under ETOPS rules myself on the B-777, I can tell you I never felt particularly jeopardized even when my closest alternate was over three hours away.  Engines have become exceedingly reliable, and under ETOPS rules I knew I always had an alternate to go to and the aircraft could fly safely on one engine.  A United Airlines B-777 lost an engine a few years ago flying from Auckland, New Zealand to Los Angeles, taking 192 minutes to safely reach its diversion airport, which was Kona, on one engine.

On a long flight, such as from Chicago to Osaka, many passengers picture a long overwater flight with nowhere to go should an engine fail.  This, however, is not the case.  This particular route, for instance, normally takes us from Chicago to a point over or near Anchorage, making Anchorage the first of three official alternates along the way.  We don't have just one alternate, but an alternate meeting the time and suitability requirements all along our route of flight.

We have a series of PET's along the way, which stands of Point of Equal Time.  For instance, let's say we take off from Chicago O'Hare bound for Osaka, Japan, and have an engine failure a few hours into the flight.  My flight plan tells me        at a certain mileage from Chicago, with wind taken into consideration, my closet alternate is to turn back to Chicago.  Another half hour or so into the flight I would see that my closest alternate is Anchorage.

Now, in actual operations, I may decide to land somewhere else much closer, such as Calgary.  I am not obligated to land at an official alternate, but must have at least one listed on my flight plan for every part of the flight as someplace suitable to go if nothing better presents itself at the time of the engine failure or other situation dictating a diversion.

If I'm already well past Anchorage, I might see that I'm closer to another alternate--Shimya--at the extreme end of the Aleutian chain, and may choose to land there instead.  The weather is lousy there much of the time, so I may find something else along the chain more suitable.

It surprises many people that aircraft are over land or near land a great deal even on transoceanic flights.  I always get lots of objections when I write that the longest overwater flight is from the west coast of the United States to Hawaii.

But what about, say, Honolulu to Tokyo?  Well, we have Midway Island and Wake Island on the way that may be used as alternate airports.

Los Angeles to Sydney?  Same thing--there are islands with airports along the way which may be used as alternates.

When we fly to Hawaii, once we pass over the west coast (if we originated farther east, for instance), we'll have just one Point of Equal Time or PET.  If there is an emergency right at the instant we pass over that geographically designated point (remember that the wind affects the position of that point) then the pilot must decide whether to go forward or turn around and go back.  It makes no difference because in terms of time there is no advantage in going one way or the other.

However, if the emergency happens anywhere on the flight other than exactly at that point, the pilot instantly knows from the flight plan whether the plane should be turned around or not.

Once, many years ago I was in Cap'n Al's (my husband, who retired from United Airlines as a B-747-400 captain) cockpit when he was a DC-8 captain.  The flight engineer discovered a fuel leak just as we were almost at the PET.  Cap'n Al decided to continue the flight to Seattle, which was our original destination, and it was in fact a little tense as we watched the fuel quantity get far lower than was desirable.  We did, of course, make it just fine.

The fuel put onto flights under ETOPS rules is very, very generous and it may surprise you to know it is not based on an engine failure at all, but on a far more critical failure:  If an airplane were to lose cabin pressure, the pilot would be obligated to descend to 10,000 feet where everyone could breathe without the use of oxygen.

The fuel burn increases substantially when flying that low, so ETOPS fuel is actually based upon a loss of cabin pressure during the flight at any point along the way and making it to the nearest diversion station with enough extra to perform a missed approach and even some other criteria.  So, on routine flights where ETOPS rules are followed but the flight is accomplished without incident, we sometimes land with far more fuel in reserve than we would on a domestic, non-ETOPS flight.

Also, if there is a segment of our flight with no suitable diversion station meeting ETOPS requirements (say, for instance, the weather is not good enough at any of the enroute alternate airports), the flight cannot depart until a suitable airport becomes available again.  I don't personally know of any cancellations or even delays for this reason, however.  There's usually someplace along each part of our route which can be designated as an alternate.

I mentioned some possible diversion airports flying to Asia.  Flying to Europe we fly the great circle route which takes us north over Nova Scotia and we often pass over or near the southern tip of Greenland, where Reykjavik Airport may be used as an alternate.  Farther east, Keflavik Airport in Iceland is often listed as an alternate.  On a more southerly route, we might see the Azores listed as an alternate airport.

For more information on ETOPS, click here:
http://en.wikipedia.org/wiki/ETOPS/LROPS

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