I was on board of this AZA786 flight from Milano to Tokyo. Nothing really dramatic though it was clear to me soon after takeoff that the climb was performed differently. I think pilots tried to go to destination anyway but had to surrender to the uncertainty of such a long trip. At first, I thought to a yaw damper trouble not noticing nothing unusual about engines or thrust. Looked like it was something related to the auto-throttle system, unable to ensure thrust to one engine.
To my knowledge, it is possible to continue flying even with such small anomaly but this is not advisable for legs longer than a couple of hours because the more you fly with such an anomaly the more the fuel consumption is irregular.
Fuel consumption is strictly calculated and fuel is strictly loaded, so chances that we had to perform another emergency landing along the Siberian way - being low on fuel - were high.
I relate with pilots and the choice to dump fuel soon after takeoff, for a long haul flight, is a very hard choice.
Few people seem to know that a plane cannot land if it is too heavy. There is the possibility that the aircraft breaks into big pieces on touchdown. This is the main reason behind the painful fuel dumping procedure.
We dumped fuel for (I guess a value of) about 400.000 USD over Genova sea performing a 30 mins pattern at FL160 and then a straight in landing to Milano with few thrust usage and some aerobrake to catch ILS from above. On touchdown, pretty strong braking with reverse thrust as well to vacate left promptly.