Narrative:

I was at 4000' on a vector to a simultaneous ILS approach to 3R at dtw on a heading of 010 degrees to intercept 3R localizer. The aircraft was set up for a coupled ILS approach and was being flown on autoplt. We were turned over to the tower in this position. The autoplt intercepted the localizer and had flown it inbound with both F/D shown localizer center for 2-3 mi when monitor told us to turn right immediately to intercept the localizer. This really caused some confusion because both F/D showed dead center on 111.5 3R localizer. We told the monitor we showed on the localizer. She said to make a right turn and intercept. Now uncertain of our position I took the aircraft off autoplt, turned right and leveled off. Then she said, 'I show you right of localizer, turn left and intercept.' this agreed with our equipment so I turned left and was intercepting the localizer and about to start a descent when a new voice said to turn right to 90 degrees and maintain 4000'. The second approach was set up at 3000' when the autoplt intercepted the localizer. When both F/D showed on localizer we asked the controller how he showed us in relation to the localizer. He said he showed us right on. When I got in the terminal I called the controller on the phone and talked to the supervisor in charge to try and find out an answer to the problem. The supervisor was very defensive and recited to me what sounded like a script for a court hearing. I still do not know what was wrong, our equipment agreed every time with ground radar except for one time. Why? (Aircraft equipment, ground equipment, veh or aircraft in critical, radar controller.)

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Original NASA ASRS Text

Title: ACR MLG ON COUPLED ILS APCH TO DTW WAS CLEARED BY ATCT LCL CTLR TO TURN RIGHT FOR LOCALIZER INTERCEPT WHEN ACFT WAS ALREADY ON THE LOCALIZER. AFTER RIGHT TURN ACFT WAS CLEARED TO TURN LEFT FOR INTERCEPT, THEN SUPVR TOOK OVER AND VECTORED ACFT OUT OF PATTERN FOR A SECOND UNEVENTFUL APCH.

Narrative: I WAS AT 4000' ON A VECTOR TO A SIMULTANEOUS ILS APCH TO 3R AT DTW ON A HDG OF 010 DEGS TO INTERCEPT 3R LOC. THE ACFT WAS SET UP FOR A COUPLED ILS APCH AND WAS BEING FLOWN ON AUTOPLT. WE WERE TURNED OVER TO THE TWR IN THIS POS. THE AUTOPLT INTERCEPTED THE LOC AND HAD FLOWN IT INBND WITH BOTH F/D SHOWN LOC CENTER FOR 2-3 MI WHEN MONITOR TOLD US TO TURN RIGHT IMMEDIATELY TO INTERCEPT THE LOC. THIS REALLY CAUSED SOME CONFUSION BECAUSE BOTH F/D SHOWED DEAD CENTER ON 111.5 3R LOC. WE TOLD THE MONITOR WE SHOWED ON THE LOC. SHE SAID TO MAKE A RIGHT TURN AND INTERCEPT. NOW UNCERTAIN OF OUR POS I TOOK THE ACFT OFF AUTOPLT, TURNED RIGHT AND LEVELED OFF. THEN SHE SAID, 'I SHOW YOU RIGHT OF LOC, TURN LEFT AND INTERCEPT.' THIS AGREED WITH OUR EQUIP SO I TURNED LEFT AND WAS INTERCEPTING THE LOC AND ABOUT TO START A DSCNT WHEN A NEW VOICE SAID TO TURN RIGHT TO 90 DEGS AND MAINTAIN 4000'. THE SECOND APCH WAS SET UP AT 3000' WHEN THE AUTOPLT INTERCEPTED THE LOC. WHEN BOTH F/D SHOWED ON LOC WE ASKED THE CTLR HOW HE SHOWED US IN RELATION TO THE LOC. HE SAID HE SHOWED US RIGHT ON. WHEN I GOT IN THE TERMINAL I CALLED THE CTLR ON THE PHONE AND TALKED TO THE SUPVR IN CHARGE TO TRY AND FIND OUT AN ANSWER TO THE PROB. THE SUPVR WAS VERY DEFENSIVE AND RECITED TO ME WHAT SOUNDED LIKE A SCRIPT FOR A COURT HEARING. I STILL DO NOT KNOW WHAT WAS WRONG, OUR EQUIP AGREED EVERY TIME WITH GND RADAR EXCEPT FOR ONE TIME. WHY? (ACFT EQUIP, GND EQUIP, VEH OR ACFT IN CRITICAL, RADAR CTLR.)

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.