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

🇺🇸 N39418 - Boeing 737NG 924ER/W - United Airlines UAL1612/UA1612 (SFO-ORD-MEM) - 4.6 mi away @ 38850 ft, heading SSW at 522 mph. Spotted 5x before! [09:21:46 PM CDT] #A49441 #N39418 #B739 #UNITED #UAL1612 #UA1612 #ADSB #ADSBbot