Narrative:

ATIS for arrival at yyz called for landing runways 24L/right. Set up initially for 24L approach. Cleared for and executed booti 1 arrival with runway 24 profile descent. Switched to arrival, given heading and further descent for vectors to 24R. Captain acknowledged radio call and vectors to 24R. We both then changed to 24R approach plates and ADF and locs were retuned accordingly. Given downwind vector and descent. Switched to second arrival controller. He gave turn to base, then final turn to 290 degrees, 4000', and 'cleared approach, cleared to descend on G/south.' captain acknowledged vector and altitude and clearance for ILS 24R approach. G/south started down but no localizer intercept yet. Started down G/south (clearance to 'descend on G/south') heading 290 degrees. Approach called and gave immediate left turn to 180 degrees and informed us of overshooting localizer. Captain said we had been cleared approach for 24R. Controller said, 'no, 24L.' we said we would have to be vectored out for another approach to 24L, which concluded uneventfully. We were IMC the entire approach period and saw no other traffic and were not informed of a traffic conflict. The next day we were notified of a 'loss of IFR sep' incident. Cannot understand how this miscom occurred. We understood and readback the initial approach for 24R.

Related reports:

Google
 

Original NASA ASRS Text

Title: ACR WDB CLEARED FOR APCH AND READ BACK 24R. ON APCH THEY WERE TOLD CLEARED FOR 24L. VECTORED OUT FOR SECOND APCH.

Narrative: ATIS FOR ARR AT YYZ CALLED FOR LNDG RWYS 24L/R. SET UP INITIALLY FOR 24L APCH. CLRED FOR AND EXECUTED BOOTI 1 ARR WITH RWY 24 PROFILE DSCNT. SWITCHED TO ARR, GIVEN HDG AND FURTHER DSCNT FOR VECTORS TO 24R. CAPT ACKNOWLEDGED RADIO CALL AND VECTORS TO 24R. WE BOTH THEN CHANGED TO 24R APCH PLATES AND ADF AND LOCS WERE RETUNED ACCORDINGLY. GIVEN DOWNWIND VECTOR AND DSCNT. SWITCHED TO SECOND ARR CTLR. HE GAVE TURN TO BASE, THEN FINAL TURN TO 290 DEGS, 4000', AND 'CLRED APCH, CLRED TO DSND ON G/S.' CAPT ACKNOWLEDGED VECTOR AND ALT AND CLRNC FOR ILS 24R APCH. G/S STARTED DOWN BUT NO LOC INTERCEPT YET. STARTED DOWN G/S (CLRNC TO 'DSND ON G/S') HDG 290 DEGS. APCH CALLED AND GAVE IMMEDIATE LEFT TURN TO 180 DEGS AND INFORMED US OF OVERSHOOTING LOC. CAPT SAID WE HAD BEEN CLRED APCH FOR 24R. CTLR SAID, 'NO, 24L.' WE SAID WE WOULD HAVE TO BE VECTORED OUT FOR ANOTHER APCH TO 24L, WHICH CONCLUDED UNEVENTFULLY. WE WERE IMC THE ENTIRE APCH PERIOD AND SAW NO OTHER TFC AND WERE NOT INFORMED OF A TFC CONFLICT. THE NEXT DAY WE WERE NOTIFIED OF A 'LOSS OF IFR SEP' INCIDENT. CANNOT UNDERSTAND HOW THIS MISCOM OCCURRED. WE UNDERSTOOD AND READBACK THE INITIAL APCH FOR 24R.

Data retrieved from NASA's ASRS site as of August 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.