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

🇺🇸 N29985 - Boeing 787 9 - United Airlines UAL1147/UA1147, Washington Dulles (IAD) to San Francisco (SFO) - 4.7 mi away @ 38950 ft, heading W at 476 mph. Spotted once before. [09:24:01 AM CST] #A31A77 #N29985 #B789 #UNITED #UAL1147 #UA1147 #autopilot #ADSB #ADSBbot