Originally Posted by
MarkerInbound
What's odd is the OP says this was after a 10 hour flight. Even if the aircraft was topped off to tanker fuel I can't imagine any airliner more than half full after 10 hours. I've seen frost on the bottom side of the wing many times. Boeing has guidance as to how much is allowed for departure on some types..
"Half full' can still mean near full wing-tanks but an empty center tank.