Originally Posted by
UnderneathTheRadar
I think we've already established that for QF9/10 to work - its LHR or LGW only due to the disruption factor of going elsewhere - departing for an alternate and betting the sheep station on an improvement is very different to departing better than CAT1 and running the risk of a deterioration to the point that no CAT3B is possible (I'm not a flyer for a living - out of curiosity, what are the rules if an airfield goes below CAT1 when enroute for a ULR flight? Must re-plan including fuel to an alternate - enough fuel to miss then divert or, if not enough for that, must divert?)
Doesn't explain why it didn't depart though - the good ol'fashion rumour about a new flight planning software sounds pretty Qantas-like also.
All airlines will have their own rules at replanning en route. From my experience in Uk and based at Lhr, vis lower than CatIII happens very infrequently, cloud base is not a factor. So unless there are long ATC delays you are guaranteed to land with the reliability of modern avionics. Most of the LR flights on my airline arrived between
0500 0700 as QF Perth, so no long ATC delays at that time, and of course 2 Cat III parallel landing runways available, 3 if you include LGW which is approx the same fuel from the arr Fix.