Thanks, keithl.
I appreciate Rainboe's point of view and his environmental concerns. I feel, however, that the 747 should have turned back. The failure of one engine may have been a link in the chain of an accident.
With regard to the A319 electrical power anomaly, the aircraft should have "Landed ASAP". A UK charter airline had a similar incident in 1998 with an A320 during take-off. The AAIB were very concerned about that incident as well. Their concerns centred on the technical failures rather than crew actions.