HH,
you also sometimes get QF operating from T4
Are you sure? I thought all QANTAS ops were now from T3 with some codeshares from T3 & T5.
For info:
I understand that, from 31 Mar 2013, the BA15 will operate as a B777-300ER LHR-SIN-SYD from T5 and the BA11 B744 to SIN also moves to T5.
The reason is that, although BA and Qantas remain in the Oneworld Alliance, Qantas is planning to move its hub from Singapore to Dubai.