Narrative:

Vectored to final approach course for the ILS 4 lga at 2700 ft MSL. Localizer and GS captured and aircraft began IMC coupled approach. Heading discrepancies noted during approach and by 1500 ft, the localizer needle deviated to full scale. Initiated a missed approach, climbed to assigned altitude, advised ATC of erroneous heading indications and declared an emergency. ATC confirmed syr was VMC (9000 ft overcast 10 SM visibility). Proceeded to syr and landed normally.

Google
 

Original NASA ASRS Text

Title: A B737-300 CAPT RPTED THAT HIS ACFT'S LOC GS FAILED WHILE ON APCH TO LGA IN SOLID IMC. HE DECLARED AN EMER AND DIVERTED TO VFR CONDITIONS AT SYR.

Narrative: VECTORED TO FINAL APCH COURSE FOR THE ILS 4 LGA AT 2700 FT MSL. LOC AND GS CAPTURED AND ACFT BEGAN IMC COUPLED APCH. HDG DISCREPANCIES NOTED DURING APCH AND BY 1500 FT, THE LOC NEEDLE DEVIATED TO FULL SCALE. INITIATED A MISSED APCH, CLBED TO ASSIGNED ALT, ADVISED ATC OF ERRONEOUS HDG INDICATIONS AND DECLARED AN EMER. ATC CONFIRMED SYR WAS VMC (9000 FT OVCST 10 SM VISIBILITY). PROCEEDED TO SYR AND LANDED NORMALLY.

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.