+ // Get the frequency of a given service at a given airport
+ // Returns zero if not found
+ unsigned short int GetFrequency(string ident, atc_type tp);
+
+ // Register the fact that the AI system wants to activate an airport
+ bool AIRegisterAirport(string ident);
+
+ // Register the fact that the comm radio is tuned to an airport
+ bool CommRegisterAirport(string ident, int chan, atc_type tp);
+