Join Date: Dec 2017
Location: In the Land Beyond OHare
Programs: 3RR, UA, BA, AA, HH, Marriott RW,
Posts: 202
ATS (the train) is not operational M-F due to system upgrades, so in the majority of cases using it will not be an option.
https://www.flychicago.com/ohare/ServicesAmenities/services/Pages/ATS.aspx