Narrative:

Approximately 150 mi out of dtw we were in a descent while the captain copied the ATIS broadcast which stated the WX was 2000 ft overcast and 5 mi visibility, wind 240 degree at 5 KTS. It also remarked that runway 21R was closed. I entered the 21L ILS into the ship's FMC, dialed in the frequency and course, and identified the signal. Descending through 12000 ft MSL we read and responded to the approach checklist as per our carrier's standard operating procedures (SOP). Within the checklist is the challenge 'frequencys and courses' of which, still in anticipation, I responded 'set and checked' for ILS 21L. Entering the dtw area over polar intersection we proceeded direct to the field. Approximately 20 mi out we were given a vector to final and were advised a new ATIS was available and to expect the ILS to runway 21R. I immediately entered the new approach into the FMC and activated it. Meanwhile the captain recopied the ATIS and wrote down any pertinent changes. We were then assigned a heading of 130 degree to intercept the localizer, maintain 3000 ft to rouge intersection and then cleared for the approach. I verbally noted as we intercepted the localizer that the inertials seemed to be off a little because the course in the CRT was lining up to the right of the aircraft symbol. The captain agreed and said that he would write them up in the ship's logbook when we were on the ground. Immediately after his response approach control told us we were east of course and to turn to a heading of 240 degree and reintercept the localizer. We responded by telling him that according to our instruments it appeared as if we were right on course. At that point I looked at the frequency and discovered that the frequency for the 21L localizer was still dialed in. In actuality we had intercepted the localizer to the parallel runway! I made an immediate turn toward the correct localizer as the captain dialed in the correct frequency. An uneventful approach and landing followed.

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Original NASA ASRS Text

Title: AFTER RWY AND ILS CHANGE BY APCH CTL, ACR FLT CREW MAKES APCH TO WRONG ILS RWY.

Narrative: APPROX 150 MI OUT OF DTW WE WERE IN A DSCNT WHILE THE CAPT COPIED THE ATIS BROADCAST WHICH STATED THE WX WAS 2000 FT OVERCAST AND 5 MI VISIBILITY, WIND 240 DEG AT 5 KTS. IT ALSO REMARKED THAT RWY 21R WAS CLOSED. I ENTERED THE 21L ILS INTO THE SHIP'S FMC, DIALED IN THE FREQ AND COURSE, AND IDENTIFIED THE SIGNAL. DESCENDING THROUGH 12000 FT MSL WE READ AND RESPONDED TO THE APCH CHECKLIST AS PER OUR CARRIER'S STANDARD OPERATING PROCS (SOP). WITHIN THE CHECKLIST IS THE CHALLENGE 'FREQS AND COURSES' OF WHICH, STILL IN ANTICIPATION, I RESPONDED 'SET AND CHECKED' FOR ILS 21L. ENTERING THE DTW AREA OVER POLAR INTXN WE PROCEEDED DIRECT TO THE FIELD. APPROX 20 MI OUT WE WERE GIVEN A VECTOR TO FINAL AND WERE ADVISED A NEW ATIS WAS AVAILABLE AND TO EXPECT THE ILS TO RWY 21R. I IMMEDIATELY ENTERED THE NEW APCH INTO THE FMC AND ACTIVATED IT. MEANWHILE THE CAPT RECOPIED THE ATIS AND WROTE DOWN ANY PERTINENT CHANGES. WE WERE THEN ASSIGNED A HDG OF 130 DEG TO INTERCEPT THE LOCALIZER, MAINTAIN 3000 FT TO ROUGE INTXN AND THEN CLRED FOR THE APCH. I VERBALLY NOTED AS WE INTERCEPTED THE LOCALIZER THAT THE INERTIALS SEEMED TO BE OFF A LITTLE BECAUSE THE COURSE IN THE CRT WAS LINING UP TO THE RIGHT OF THE ACFT SYMBOL. THE CAPT AGREED AND SAID THAT HE WOULD WRITE THEM UP IN THE SHIP'S LOGBOOK WHEN WE WERE ON THE GND. IMMEDIATELY AFTER HIS RESPONSE APCH CTL TOLD US WE WERE E OF COURSE AND TO TURN TO A HDG OF 240 DEG AND REINTERCEPT THE LOCALIZER. WE RESPONDED BY TELLING HIM THAT ACCORDING TO OUR INSTS IT APPEARED AS IF WE WERE RIGHT ON COURSE. AT THAT POINT I LOOKED AT THE FREQ AND DISCOVERED THAT THE FREQ FOR THE 21L LOCALIZER WAS STILL DIALED IN. IN ACTUALITY WE HAD INTERCEPTED THE LOCALIZER TO THE PARALLEL RWY! I MADE AN IMMEDIATE TURN TOWARD THE CORRECT LOCALIZER AS THE CAPT DIALED IN THE CORRECT FREQ. AN UNEVENTFUL APCH AND LNDG FOLLOWED.

Data retrieved from NASA's ASRS site as of July 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.