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

🇺🇸 N639FR - Airbus A321 271NXSL - Frontier Airlines FFT1842/F91842, Austin-Bergstrom (AUS) to Philadelphia (PHL) - 4.7 mi away @ 39500 ft, heading ENE at 571 mph. Spotted 11x before! [09:04:49 PM CDT] #A85FB8 #N639FR #A21N #FRONTIER_FLIGHT #FFT1842 #F91842 #ADSB #ADSBbot