Good catch Wiggy. I did not mean to give the impression that the crew just shows up over the station and dumps fuel willy nilly. You aptly brought out the good point that this would be done only if the crew wished to bring the aircraft down to max landing weight. Even that assumes that the aircraft was still over MLW upon arrival at the ETOPS divert staion.
Wiggy also brings out the point that this would be a choice--some emergencies would not allow the luxury of dumping down to MLW. A post flight overweight landing might at that time be the very least of anyone's worries and so a beeline would be made for the approach and landing. Aircraft land just fine overweight.
What I was trying to bring out is the fine balance of communication between crew and dispatcher and the captain's judgement. Taking a course to one diversion field will, of course, close to the door to others.
I also agree with Wiggy that one should not get too drawn into this being solely a "two engine" issue. Diverts have occurred on all types of transports and it is the mindset that goes into this planning and, if need be, executing that is important. A 747-400 with a cargo fire that one suspects did not go out for example would require this type of planning/diversion.
I cannot speak for all ETOPS routes around the world, but yes, for flights over Alaska to Asia from the United States there are sometimes reroutes if one of the ETOPS alternates is not usable. We also see this on the Polar Routes (over the top of the world) but that is usually known ahead of time and allowance and planning is made before the flight even leaves the ground. In other words if Polar 1,2, and 3 are not looking good, it might just be a flight over Alaska and onward--adding a lot of time to the flight.
The North Atlantic planning can be stretched around before one enters the ETOPS area--particularly if one has the has the luxury of using 180 minute ETOPS so that something like Shannon and Goose Bay are all that is needed--with Kef being left out.
Also, for those who do not know--ETOPS is more that 60 minutes from a suitable so just because one is "feet wet" over the water does not mean that one is yet under ETOPS rules. I know the pilots all know this but it is a common misconception for our guests and interested parties. In fact, over the real far North Atlantic the actual time in ETOPS can be relatively short.
Last edited by Uncle Fred; 15th Jan 2013 at 04:04.