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

🇺🇸 N403AS - Boeing 737NG 990ER/W - Alaska Airlines ASA575/AS575, St Louis Lambert (STL) to Seattle-Tacoma (SEA) - 3.3 mi away @ 12600 ft, heading NW at 404 mph. Spotted 6x before! [07:05:13 PM CDT] #A4B7D7 #N403AS #B739 #ALASKA #ASA575 #AS575 #TakingOff #Departure #ADSB #ADSBbot