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

🇺🇸 N17347 - Boeing 737MAX 8 - United Airlines UAL2423/UA2423, San Francisco (SFO) to Baltimore/Washington Thurgood Marshall (BWI) - 4.4 mi away @ 39225 ft, heading E at 534 mph. Spotted 2x before! [04:39:29 AM CDT] #A12756 #N17347 #B38M #UNITED #UAL2423 #UA2423 #ADSB #ADSBbot