WRONG ARPT APCH BY ACR MLG.

Narrative

THIS WAS A CARGO FLT FROM ILN TO BIL TO GEG TO BOI. ON THE APCH TO GEG; THE WX WAS MIDDLE TO HIGH CLOUDS; BROKEN TO OVCST; CEILING ABOUT 7000 FT MSL. WE WERE BEING VECTORED TO GEG FOR A VISUAL APCH TO RWY 21. WE HAD THE OUTER COMPASS LOCATOR AND ILS TUNED AND IDENTED FOR RWY 21. AS WE WERE BEING VECTORED; WE COULD NOT IDENT THE RWY DUE TO HAZE AND MORNING SUN. AS APCH CTL GAVE US A FINAL VECTOR TO INTERCEPT THE ILS 21; THE CAPT CALLED OUT VISUAL CONTACT WITH THE RWY. I RELAYED TO APCH. WE WERE CLRED TO TWR AND CLRED FOR THE VISUAL. HOWEVER; THE ILS LOC AND NDB DIDN'T AGREE WITH THE RWY WE WERE FLYING TO. ABOUT THIS TIME GEG TWR CALLED AND SAID WE WERE HDG TO SKA AFB. WE THEN RECEIVED A CLRNC FOR A L 360 DEG TURN AND LANDED AT GEG ON RWY 21 WITHOUT INCIDENT. WHAT WE SHOULD HAVE DONE WITH THE HAZE WAS INTERCEPT THE ILS LOC THEN IDENT THE RWY. BUT I WAS HAPPY THAT; BY FOLLOWING COMPANY PROCS; WE KNEW SOMETHING WAS WRONG AND I DON'T BELIEVE WE WOULD HAVE LANDED AT SKA AFB. BUT STILL WE WERE TOO QUICK TO CALL VISUAL CONTACT. IT HAD BEEN A LONGER THAN USUAL NIGHT AND FATIGUE AND THE DESIRE TO GET THE FLT DONE ALMOST CAUSED A VIOLATION. SUPPLEMENTAL INFORMATION FROM ACN 243180: I HAD NEVER FLOWN INTO GEG ARPT; HOWEVER MY FO HAD BEEN THERE MANY TIMES. THE FO CALLED IT IN SIGHT TO CTLR AS HE ALSO VERIFIED IT AS BEING RWY 21 AT GEG. WE WERE ON ABOUT A 5 MI FINAL WHEN I SAID THE LOC AND GS WERE NOT INDICATING PROPERLY FOR THAT RWY.