Narrative:

While on approach to dfw, runway 18L side-step to runway 18R, we experienced a false GS and localizer capture. While on the initial vector at 3000 ft, we were cleared to 2700 ft, placed on a 30 degree intercept heading and cleared for the approach. The frequency of 110.55 was tuned and idented. My instruments indicated a normal localizer capture and then in sequence a normal GS capture. Just after localizer and GS capture, a different controller's voice advised us that we were lined up with the runway 17 complex. He told us to turn right and reintercept the runway 18L localizer and GS. We advised the controller we had runway 18R in sight, we were cleared for visual approach to runway 18R. The captain advised the controller that we were tuned to 110.55 for runway 18L and still not getting proper indications. Were they having a problem with the ILS frequency? It was too busy and got no response. We were handed off to tower and made a normal landing. After landing I called the west tower. I asked the duty supervisor if they were having any problems with the runway 18L ILS frequency 110.55? He said they were working on changing the frequencys for the ILS's but had not worked on runway 18L this date. Still not sure why we had all normal indications on localizer and GS for runway 18L but were lined up with runway 17 complex. The tower supervisor advised he would check on problem, but had no other complaints. Callback conversation with reporter revealed the following information: the reporter was flying the B737-200 for an air carrier. Both ILS's were properly tuned and idented. Horizontal visibility was reduced by haze, but vertical visibility was good at the approach altitudes. The reporter's aircraft was the only one that the reporter knows about that had this problem. NOTAMS showed that there was to be work on the ILS's that day. This crew flew the same aircraft for 2 more legs that day with no problem. Supplemental information from acn 314664: approach control stated that we had been lined up for the 17 runways. I suspect that someone had changed frequency for ILS runway 18L during our approach. I cannot think of how the false localizer on might have occurred otherwise.

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Original NASA ASRS Text

Title: TRACK DEV ACR MLG LINED UP ON THE WRONG SIDE OF THE ARPT. MULTIPLE RWY OP PARALLEL RWYS.

Narrative: WHILE ON APCH TO DFW, RWY 18L SIDE-STEP TO RWY 18R, WE EXPERIENCED A FALSE GS AND LOC CAPTURE. WHILE ON THE INITIAL VECTOR AT 3000 FT, WE WERE CLRED TO 2700 FT, PLACED ON A 30 DEG INTERCEPT HDG AND CLRED FOR THE APCH. THE FREQ OF 110.55 WAS TUNED AND IDENTED. MY INSTS INDICATED A NORMAL LOC CAPTURE AND THEN IN SEQUENCE A NORMAL GS CAPTURE. JUST AFTER LOC AND GS CAPTURE, A DIFFERENT CTLR'S VOICE ADVISED US THAT WE WERE LINED UP WITH THE RWY 17 COMPLEX. HE TOLD US TO TURN R AND REINTERCEPT THE RWY 18L LOC AND GS. WE ADVISED THE CTLR WE HAD RWY 18R IN SIGHT, WE WERE CLRED FOR VISUAL APCH TO RWY 18R. THE CAPT ADVISED THE CTLR THAT WE WERE TUNED TO 110.55 FOR RWY 18L AND STILL NOT GETTING PROPER INDICATIONS. WERE THEY HAVING A PROB WITH THE ILS FREQ? IT WAS TOO BUSY AND GOT NO RESPONSE. WE WERE HANDED OFF TO TWR AND MADE A NORMAL LNDG. AFTER LNDG I CALLED THE W TWR. I ASKED THE DUTY SUPVR IF THEY WERE HAVING ANY PROBS WITH THE RWY 18L ILS FREQ 110.55? HE SAID THEY WERE WORKING ON CHANGING THE FREQS FOR THE ILS'S BUT HAD NOT WORKED ON RWY 18L THIS DATE. STILL NOT SURE WHY WE HAD ALL NORMAL INDICATIONS ON LOC AND GS FOR RWY 18L BUT WERE LINED UP WITH RWY 17 COMPLEX. THE TWR SUPVR ADVISED HE WOULD CHK ON PROB, BUT HAD NO OTHER COMPLAINTS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR WAS FLYING THE B737-200 FOR AN ACR. BOTH ILS'S WERE PROPERLY TUNED AND IDENTED. HORIZ VISIBILITY WAS REDUCED BY HAZE, BUT VERT VISIBILITY WAS GOOD AT THE APCH ALTS. THE RPTR'S ACFT WAS THE ONLY ONE THAT THE RPTR KNOWS ABOUT THAT HAD THIS PROB. NOTAMS SHOWED THAT THERE WAS TO BE WORK ON THE ILS'S THAT DAY. THIS CREW FLEW THE SAME ACFT FOR 2 MORE LEGS THAT DAY WITH NO PROB. SUPPLEMENTAL INFO FROM ACN 314664: APCH CTL STATED THAT WE HAD BEEN LINED UP FOR THE 17 RWYS. I SUSPECT THAT SOMEONE HAD CHANGED FREQ FOR ILS RWY 18L DURING OUR APCH. I CANNOT THINK OF HOW THE FALSE LOC ON MIGHT HAVE OCCURRED OTHERWISE.

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.