I've flown PVG-ORD twice. Once in the early Spring and once in the mid Summer. I've flown ORD-PVG twice. Both times in the summer.

During this time of year, it will be light when you takeoff. It will, however, get dark within two to two and half hours after takeoff as the airplane is flying toward the sun and the sun is moving toward you. It will be dark for approximately five to six hours. You will land in daylight.

I imagine that it will be dark for much of, if not all the flight in the dead of winter.

PVG-ORD does not take a polar route. You fly over Japan and then track as you would on an NRT/KIX-ORD flight.

As for ORD-PVG, the flight takes a polar route and, as such, it is light the whole time in the summer. In the winter, I expect it will be light on departure and will get dark as you track further north, but will be light again as you arrive.

Overall, it is a fine flight and a reliable Flagship Suite flight (for those of us in F).