I only knew of their chopper located at Mercy Jefferson. Last I heard Air Evac was in Hannibal. I even had the chance to see their base (mobile home) a couple years ago. I guess they are expanding. Try the main ARCH freq which I think also goes by Air Comm or something like it, for the St Louis area. ARCH used to have UHF freqs all over MO & IL but not sure what all they do now. I know it's not much but I hope it helps.