AN HS125 FLC STARTED AN APCH USING THE WRONG NAVAID AT ORD.

Narrative

WHILE APCHING ORD FROM THE E; WE WERE VECTORED TO THE ARPT FOR A VISUAL APCH TO RWY 22L. THE LOC COURSE OF 222 DEGS WAS SET BY THE FO ON THE CAPT'S HSI. THE LOC FREQ WAS TUNED IN THE STANDBY POS AND THE VOR (ORD) WAS TUNED IN THE ACTIVE POS. THE CAPT WAS NOT AWARE THE VOR AND NOT THE LOC WAS TUNED. THE ACFT WAS NAVED TO RWY 22L VIA THE VOR COURSE INSTEAD OF THE LOC COURSE. WHILE ON BASE TO FINAL APCH; A B727 WAS SEEN ON OUR TCASII AND VISUALLY AND OUR TURN RATE WAS INCREASED SO AS TO AVOID THAT ACFT WHICH WAS LNDG ON RWY 22R. OUR TCASII GAVE US A TA AND AN RA TO AVOID THE B727. THE MISLOCATION OF OUR ACFT WAS DISCOVERED BY THE VISUAL SIGHTING OF THE B727 ON FINAL FOR RWY 22R. THE PROB COULD HAVE BEEN AVOIDED IN SEVERAL WAYS: 1) THE FO SHOULD HAVE TUNED ALL RADIOS PERTAINING TO THE APCH. 2) THE CAPT SHOULD VERIFY WHAT RADIOS ARE TUNED AND WHICH ARE NOT TUNED. TOO MANY ASSUMPTIONS WERE MADE WITHOUT VERIFICATION. 3) VISUAL APCHS TO BUSY ARPTS SHOULD NOT UTILIZED. I THINK CREW INACTIONS CAUSED THIS SIT TO DEVELOP (IE; ACFT BEING BTWN BOTH PARALLEL RWYS). BOTH PLTS IN THE MISPLACED ACFT THOUGHT THE OTHER PLT WAS AWARE OF THE NAV AND RADIO SET-UP.