Quote:
Please keep in mind that after dispatch you only require to show landing minima at your destination (and CAT3 minima can be applied - the minima is irrelevant at the alternate after dispatch)
Certainly not in QF who happen to own one of the two aircraft that diverted. I'm not going to get into a debate about the merits of the fuel policy or otherwise (that's been done to death in the last code of months).
Alternate criteria applies at the destination preflight and inflight - typically 400'/1600m at an airport with multiple precision approaches. If you hit your PSD - called DPA - and the weather at destination is below alternate criteria, you go to your suitable alternate.
If it deteriorates after DPA, you continue, couple it up and fill out the paperwork.
So, in summary, the QF aircraft was legally required to divert. They diverted and the weather at the alternate deteriorated with unforecast fog after they diverted.
I don't know Virgin's fuel policy and won't comment on their circumstances.