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

🇺🇸 N121CZ - Embraer EMB-120 ER - Air Charter Express FRG9121 - 4.4 mi away @ 27975 ft, heading NNE at 351 mph. Spotted for first time! [01:04:30 PM CDT] #A057B3 #N121CZ #E120 #FRG9121 #ADSB #ADSBbot