Thank you, Uncle Fred, for the patient, avuncular and informative reply. I am grateful. ETOPS regulations have long intrigued me.
It seems, if I understand Uncle Fred correctly, that the possible diversions must be the subject of at least two explicit conversations -- the first, before the engines are even started, and the second immediately before entering what Uncle Fred calls the ETOPS area. On both occasions the dispatcher and crew must bend their minds consciously to the status and availability of the designated diversions. Is that right?
SeenItAll (Post #27) writes: "The worst case scenario would have been a failure right over where ASI is located....."
This, and Uncle Fred's comments, put a further thought in my mind. Does it not follow that, as a matter of prudent planning when ETOPS is relevant, one would require a minimum of two suitable designated diversions? I ask this, because it seems to me that if one is obliged to divert then one has in effect a new destination which itself requires a diversion as a matter of normal planning.
With apologies for troubling busy people further, I would like to read comments on a thought that I've long had -- that the decision to build the 777 with two engines was taken by the actuaries and accountants.
The more engines one has the greater the operating costs. It is now more profitable to an operator, over the serviceable life of a modern jet aircraft, to pay higher premiums on a two-engined aircraft than on a three or four engined aircraft with a similar capacity and performance. This is because the modern jet engine is now so reliable and powerful that the risk of a loss due to the failure of one engine has become so low that it is commercially insurable. A loss due to the failure of more than one engine is so improbable that it is simply not even worth worrying about, so two engines will do.
But I wonder... if this is right, then surely the optimum number of engines, with an eye to ETOPS issues, is thus three?
There is some judicial recognition for the reliability of jet engines. I've lost my notes over the years, but I think I have this case right.......In the prosecution arising out of the incident involving Cessna 560 V-WCIN dealt with by the UK's AAIB (easily found), the pilot was charged with endangering etc etc etc. This, of course, does not appear in the report.
When taking off from Gibraltar one of the two jet engines was damaged but when the commander found that it would deliver reduced power he flew it to his destination (I think it was Bournemouth) for repair. There was defence evidence showing the astronomical number of hours over which identical engines had run faultlessly, and it was claimed that it was thus not an unreasonable risk to continue the flight relying on the remaining sound engine. The defence succeeded.
Still and all, we have the makings of a great disaster movie..... Our hero pilots set off in their 777 from JNB having done all the right planning, and in mid-Atlantic sustain engine failure. They divert to Ascension (making coolly frantic MAYDAY calls), dumping fuel to enable them to execute the difficult landing safely -- note what RobertS975 said (the posting immediately before Uncle Fred's): "......single engine landing at night, VOR/DME approach, no approach lights". But...... ! As they near Ascension someone makes a nasty mess on the runway they are about to use and the runway is closed.......... "Shirley, we have a problem...!"
Oh, I can see it all........