What is up with UA857 SFO-PVG???
Curiosity for those here with more experience. I am booked on UA857 next week (SFO-PVG, operated by 789 but was 744 until last week).
I have been watching this flight for some time and the delays are consistent and in many cases extensive (UA857 is on-time just 40% of the time, avg. delay of 31 minutes). The delays don't seem to fit any pattern other than inbound aircraft arrives hours before departure time, flight shows on-time until T+2 minutes, and then delays begin and accumulate. The reasons stated in the UA app for delays seem to frequently be "severe weather in our network" or "network delays have caused ..." type reasons (rarely though sometimes "aircraft servicing ...").
What is unique about this flight and the delay pattern? My initial guesses seem disprovable: it would not seem to be equipment (arrivals have been delayed 51, 72, 33, and 103 minutes, respectively, since AC switched from 744 to 789, and lots of other 789 flights with good ratings); it would not seem to be PVG ATC/Chinese authorities (UA's later SFO-PVG and LAX-PVG flights each have good on-time ratings, and ORD-PVG is on-time 90%+); it would not seem to be ex-SFO issues (UA's SFO-HKG flight departs around same time and has good on-time rating, as does the later SFO-PVG flight).
Anything special driving UA857's on-time performance? Thanks.