Atx makes ILS approach with localizer out of tolerance.

Attributes
ACN	177786
Time
Date	199104
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : den
State Reference	CO
Environment
Flight Conditions	IMC
Light	Dawn
Aircraft 1
Controlling Facilities	tower : den artcc : czqm
Operator	common carrier : air taxi
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent : approach landing other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 18500
ASRS Report	177786
Person 2
Affiliation	company : air taxi
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course none taken : anomaly accepted
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Airport
Air Traffic Incident	other
Situations
Navigational Aid	Unspecified

Narrative:

WX at den was w2x1/2S-F, RVR 1600' and runway 35L was in use. Runway 35R was closed for plowing. We were being vectored for an approach to runway 35L. While on a right downwind vector, we were informed that a new ATIS was up and runway 35R was now in use. However the RVR was not up yet. We were told RVR on runway 35R was at 800'. We asked for runway 35L because of the better RVR. On the base leg turn we were advised that runway 35R RVR was coming up and that we would be vectored for runway 35R. We tuned in the 35R ILS (109.3) and were given a vector to intercept the ILS. An aircraft ahead of us was also on the approach for 35R. Approach advised him he was left of course and lined up with 35L. He stated he had 35R ILS tuned in and showed centerline. Again he was advised he was left of course. He decided to go missed approach. We intercepted the 35R ILS at about 15 mi. Localizer, G/south and DME showed normal. Localizer had proper identify code. As we continued the approach, approach said we were left of centerline and asked us if we had 109.3 tuned in. We said we did and that we showed centerline and were on G/south. At the OM we were switched to the tower for landing clearance. We were cleared to land on 35R and again were informed we were left of course and to verify we had 109.3 tuned in. We say yes, and we still showed centerline on both navigation heads. As we broke out of the clouds and started to pick up the runway, the tower advised us we were lined up with 35L. I started a right turn away from the runway centerline to begin a missed approach, and the tower cleared us to land on 35L. I had made the right turn away from the runway because I didn't know if anyone was taking off and didn't want to make a missed approach with someone underneath me. We landed ok on 35L and taxied clear. We advised the tower that something was very wrong and that they should check their equipment. ILS 35R approachs were immediately terminated while they checked their equipment. We never learned what went wrong and approachs were later back to normal on 35R. The tower anticipated something was wrong and thankfully had kept runway 35L clear of traffic so we could land safely.

Original NASA ASRS Text

Title: ATX MAKES ILS APCH WITH LOCALIZER OUT OF TOLERANCE.

Narrative: WX AT DEN WAS W2X1/2S-F, RVR 1600' AND RWY 35L WAS IN USE. RWY 35R WAS CLOSED FOR PLOWING. WE WERE BEING VECTORED FOR AN APCH TO RWY 35L. WHILE ON A RIGHT DOWNWIND VECTOR, WE WERE INFORMED THAT A NEW ATIS WAS UP AND RWY 35R WAS NOW IN USE. HOWEVER THE RVR WAS NOT UP YET. WE WERE TOLD RVR ON RWY 35R WAS AT 800'. WE ASKED FOR RWY 35L BECAUSE OF THE BETTER RVR. ON THE BASE LEG TURN WE WERE ADVISED THAT RWY 35R RVR WAS COMING UP AND THAT WE WOULD BE VECTORED FOR RWY 35R. WE TUNED IN THE 35R ILS (109.3) AND WERE GIVEN A VECTOR TO INTERCEPT THE ILS. AN ACFT AHEAD OF US WAS ALSO ON THE APCH FOR 35R. APCH ADVISED HIM HE WAS LEFT OF COURSE AND LINED UP WITH 35L. HE STATED HE HAD 35R ILS TUNED IN AND SHOWED CENTERLINE. AGAIN HE WAS ADVISED HE WAS LEFT OF COURSE. HE DECIDED TO GO MISSED APCH. WE INTERCEPTED THE 35R ILS AT ABOUT 15 MI. LOC, G/S AND DME SHOWED NORMAL. LOC HAD PROPER IDENT CODE. AS WE CONTINUED THE APCH, APCH SAID WE WERE LEFT OF CENTERLINE AND ASKED US IF WE HAD 109.3 TUNED IN. WE SAID WE DID AND THAT WE SHOWED CENTERLINE AND WERE ON G/S. AT THE OM WE WERE SWITCHED TO THE TWR FOR LNDG CLRNC. WE WERE CLRED TO LAND ON 35R AND AGAIN WERE INFORMED WE WERE LEFT OF COURSE AND TO VERIFY WE HAD 109.3 TUNED IN. WE SAY YES, AND WE STILL SHOWED CENTERLINE ON BOTH NAV HEADS. AS WE BROKE OUT OF THE CLOUDS AND STARTED TO PICK UP THE RWY, THE TWR ADVISED US WE WERE LINED UP WITH 35L. I STARTED A RIGHT TURN AWAY FROM THE RWY CENTERLINE TO BEGIN A MISSED APCH, AND THE TWR CLRED US TO LAND ON 35L. I HAD MADE THE RIGHT TURN AWAY FROM THE RWY BECAUSE I DIDN'T KNOW IF ANYONE WAS TAKING OFF AND DIDN'T WANT TO MAKE A MISSED APCH WITH SOMEONE UNDERNEATH ME. WE LANDED OK ON 35L AND TAXIED CLR. WE ADVISED THE TWR THAT SOMETHING WAS VERY WRONG AND THAT THEY SHOULD CHK THEIR EQUIP. ILS 35R APCHS WERE IMMEDIATELY TERMINATED WHILE THEY CHKED THEIR EQUIP. WE NEVER LEARNED WHAT WENT WRONG AND APCHS WERE LATER BACK TO NORMAL ON 35R. THE TWR ANTICIPATED SOMETHING WAS WRONG AND THANKFULLY HAD KEPT RWY 35L CLR OF TFC SO WE COULD LAND SAFELY.

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.