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

🇺🇸 N54241 - Boeing 737NG 824/W - United Airlines UAL1575/UA1575 (ONT-DEN-SDF) - 5.1 mi away @ 39350 ft, heading ESE at 540 mph. Spotted 16x before! [12:34:49 PM CDT] #A6E258 #N54241 #B738 #UNITED #UAL1575 #UA1575 #ADSB #ADSBbot