Originally Posted by
blug
It is so that the crew don't need to stay in Shanghai.
If what DL does is an indication, passengers won't get off the plane at ICN. And SFO-ICN and ICN-PVG won't be sold separately.
To protect the crew. China's rules require COVID testing for every layover crew and if one tests positive, the whole crew is taken to an 'undisclosed quarantine location' for 2 weeks. UA isn't going to let that happen to its employees, so new crew in ICN flies to PVG and back without a layover.