Map of the St. Louis area showing the position and track of the aircraft described in the post.

🇺🇸 N12020 - Boeing 787 10 - United Airlines UAL435/UA435, Newark Liberty (EWR) to Los Angeles (LAX) - 4.8 mi away @ 40200 ft, heading WSW at 522 mph. Spotted once before! [08:08:11 PM CST] #A05669 #N12020 #B78X #UNITED #UAL435 #UA435 #autopilot #STL #ADSB