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

🇺🇸 N728NK - Airbus A321 271NXSL - Spirit Airlines NKS1637/NK1637, Myrtle Beach (MYR) to Chicago O'Hare (ORD) - 4.8 mi away @ 40475 ft, heading NNE at 539 mph. Spotted 4x before! [05:20:03 PM CDT] #A9C27A #N728NK #A21N #SPIRIT_WINGS #NKS1637 #NK1637 #ADSB #ADSBbot