Narrative:

We were vectored to ILS runway 4R ord. At 21 DME on ord VOR we got full scale left deflection on localizer. After about 2 seconds it came back to center. We continued the approach. At 12 DME we got full scale left deflection followed by full scale right deflection. FMC gave us an amber warning line through localizer indication and we got warning lights. We turned autoplt off and flight director off to prevent abrupt flight control inputs. We are now flying raw data and WX is 600 ft 2MI. We continued the approach. At 1100 ft AGL we get full scale deviation to the left. First officer continues to fly nice approach using map mode for direction. Localizer stays full left deflection to 600 ft. We breakout well right of course and had to correct to line up with runway. From 1100 ft to 600 ft we did not know if we should turn left, go around, or if localizer would come back to center. I now believe we had a right correction and after the last swing to the left we drifted right of course and when the localizer returned it was at full left deflection, but how would we know that. Using an erratic localizer to 600 ft, 2 mi is unacceptable. Callback conversation with reporter revealed the following information: the reporter is a captain and line instructor on the B757-200. On this flight he was giving IOE to a new first officer. The captain said that he had shown the first officer a company bulletin that warned of this localizer problem. During the approach he pointed out how difficult it would be to fly a faulty localizer to low minimums. Now, he said, he regrets pushing the approach. He said that after the flight he talked to the first officer about the approach and how he, the captain, should have performed. He also said that he talked to the chief pilot and during this conversation the chief pilot, apparently, called a facilities manager at ord who allegedly responded that nobody else had ever complained about the localizer. So the chief pilot read him the company bulletin.

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Original NASA ASRS Text

Title: AN ACR B757 FLC HAS NUMEROUS FULL SCALE DEFLECTIONS TO THEIR LOC INDICATION DURING AN ILS APCH TO RWY 4R AT ORD.

Narrative: WE WERE VECTORED TO ILS RWY 4R ORD. AT 21 DME ON ORD VOR WE GOT FULL SCALE L DEFLECTION ON LOC. AFTER ABOUT 2 SECONDS IT CAME BACK TO CTR. WE CONTINUED THE APCH. AT 12 DME WE GOT FULL SCALE L DEFLECTION FOLLOWED BY FULL SCALE R DEFLECTION. FMC GAVE US AN AMBER WARNING LINE THROUGH LOC INDICATION AND WE GOT WARNING LIGHTS. WE TURNED AUTOPLT OFF AND FLT DIRECTOR OFF TO PREVENT ABRUPT FLT CTL INPUTS. WE ARE NOW FLYING RAW DATA AND WX IS 600 FT 2MI. WE CONTINUED THE APCH. AT 1100 FT AGL WE GET FULL SCALE DEV TO THE L. FO CONTINUES TO FLY NICE APCH USING MAP MODE FOR DIRECTION. LOC STAYS FULL L DEFLECTION TO 600 FT. WE BREAKOUT WELL R OF COURSE AND HAD TO CORRECT TO LINE UP WITH RWY. FROM 1100 FT TO 600 FT WE DID NOT KNOW IF WE SHOULD TURN L, GAR, OR IF LOC WOULD COME BACK TO CTR. I NOW BELIEVE WE HAD A R CORRECTION AND AFTER THE LAST SWING TO THE L WE DRIFTED R OF COURSE AND WHEN THE LOC RETURNED IT WAS AT FULL L DEFLECTION, BUT HOW WOULD WE KNOW THAT. USING AN ERRATIC LOC TO 600 FT, 2 MI IS UNACCEPTABLE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR IS A CAPT AND LINE INSTRUCTOR ON THE B757-200. ON THIS FLT HE WAS GIVING IOE TO A NEW FO. THE CAPT SAID THAT HE HAD SHOWN THE FO A COMPANY BULLETIN THAT WARNED OF THIS LOC PROB. DURING THE APCH HE POINTED OUT HOW DIFFICULT IT WOULD BE TO FLY A FAULTY LOC TO LOW MINIMUMS. NOW, HE SAID, HE REGRETS PUSHING THE APCH. HE SAID THAT AFTER THE FLT HE TALKED TO THE FO ABOUT THE APCH AND HOW HE, THE CAPT, SHOULD HAVE PERFORMED. HE ALSO SAID THAT HE TALKED TO THE CHIEF PLT AND DURING THIS CONVERSATION THE CHIEF PLT, APPARENTLY, CALLED A FACILITIES MGR AT ORD WHO ALLEGEDLY RESPONDED THAT NOBODY ELSE HAD EVER COMPLAINED ABOUT THE LOC. SO THE CHIEF PLT READ HIM THE COMPANY BULLETIN.

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.