I know you depend on me for "positive" news so here we go -
1 - Why it's more likely to happen in summer
http://www.smh.com.au/travel/travel-news/letters-surprise-landing-20110608-1fshf.html
"I was on a Qantas flight from Dallas to Brisbane on May 30 when it had to make an unscheduled stop in Noumea to refuel.
What has not been reported is the reason for the refuel. Qantas already knows about the headwinds that aircraft face flying east to west. However, the aircraft could not take on a full load of fuel in Dallas due to the high temperature on the tarmac there.
Qantas management will need to think seriously about the sense in trying to fly directly to and from Dallas, especially at a time of year when temperatures are very high."
2 - The problems overall...and why it might well happen again...and why your luggage might arrive on a different flight
http://www.smh.com.au/travel/travel-news/trouble-in-texas-20110608-1fsh0.html
Part of the story...
"At least one of the return flights was forced to set down in Noumea, New Caledonia, for extra fuel about two hours short of the scheduled refuelling stop in Brisbane. (The journey from Dallas to Sydney is against prevailing westerly headwinds and requires a fuel stop in Brisbane.)
Another flight was forced to offload two luggage containers at Dallas "because of a late increase in the forecast headwind", according to the head of Qantas's integrated operations centre, Alan Milne."
Enjoy