They eventually did put me onto QF2 SIN-SYD, thereby avoiding the long layover in SIN. Both QF2 pilots said it was due to missing the curfew in LHR.
Does this sound like it will be eligible for UK261 compensation? If so, how do I argue that it's not outside of their control? The fact that they schedule an aircraft from one route, directly onto a route with a known curfew seems like poor planning on their part. I don't know how to argue that with them.
I doubt it. The problem here isn't the schedule. It is hard to schedule flights between LHR and SYD as it is, with the long travel time and curfews on each end.
The aircraft in question departed LAX as QF12 on 16JUN at 1516. It should have left at 2340 15JUN.
QF12 then arrived at SYD at 2234 17JUN, where QF1 was awaiting at 1510 departure.
With no way to turn around the aircraft and depart again within 26 minutes and no available aircraft, QF1 17JUN was delayed overnight and departed 0640 18JUN to arrive LHR at 2240 18JUN. Again, too late for the scheduled departure of QF2 at 2055, and also too late to turn around before LHR curfew. So it was again delayed overnight to depart LHR at 0924.
The delay to QF12 on the 15th may have been the reason the aircraft was late, but the curfews in SYD and LHR were the reason for incresing the delay to the aircraft. Had the curfews not been in place one or both of the delayed QF1/2 would not have happened.
If you're going to argue with them for UK261, you could try questioning the delay out of LAX, but they'll likely just respond with curfews caused the delay to your flight.
Maybe question why the delayed QF1 was in SIN for 4 hours on 18JUN instead of the normal 2 hours. With that additional 2 hours in LHR, it may have been possible to depart the delayed QF2 before the LHR curfew.
Some years ago, BA refused to check me through to my connecting flight in DXB (on QF)
and their flight was delayed. Tech issue with planned aircraft, aircraft swapped with another inbound aircraft. Both issues (refusal to check through + tech caused delay) were controllable by BA. If either hadn't happened, I would have made the connection. I arrived at my destination 23 hours late. BA refused to pay up the (then) EU261 compensation claiming that both issues weren't within their control.