AN ACR ACFT LINES UP WITH THE WRONG RWY DURING AN ILS APCH. THE CREW HAD SELECTED THE WRONG ILS FREQ FOR THE MULTIPLE RWY OP PARALLEL RWYS.

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ARRIVING STL ASSIGNED RWY 30R VECTORS FOR THE APCH. LOC FREQ RWY 30R IS 111.3. FREQ WAS MISSET BY FLC TO 111.5 WHICH IS LOC FREQ FOR RWY 30L. STL WAS USING RWY 30R FOR ARRS AND RWY 30L FOR DEPS. ACFT WAS ON AUTOPLT AND INTERCEPTED RWY 30L LOC AND BEGAN TO TRACK INBOUND. APPROX 3 MI FROM TOUCHDOWN STL TWR ADVISED THAT WE APPEARED TO BE LINED UP WITH RWY 30L INSTEAD OF RWY 30R. REALIZING OUR ERROR WE IMMEDIATELY SELECTED 111.3 FOR LOC RWY 30R; MADE HDG ADJUSTMENT AND SIDESTEPPED TO RWY 30R. LANDED ACFT WITHOUT INCIDENT. WHILE THIS ERROR RESTS WITH THE FLC; THE SIT REVEALS A COMMON PROB. FLCS THAT OPERATE FREQUENTLY AT GIVEN ARPTS TEND TO MEMORIZE COMMONLY USED FREQS AND OFTEN DO NOT REFER TO NAV CHARTS FOR FREQ OR OTHER INFO. IN THIS CASE; WHERE THE FREQS ARE VERY SIMILAR -- 111.3 AND 111.5 (4 OF 5 DIGITS IDENTICAL) THE MISTAKE OF USING HABITUAL KNOWLEDGE IN SELECTING FREQS CAN BE CAUSE FOR A MAJOR ERROR. I THINK THAT LOC FREQS FOR PARALLEL APCHS SHOULD BE MORE DISSIMILAR AND THEREBY MORE SELECTIVE FOR THE INDIVIDUAL PARALLEL RWY.