A DC9-50 IS VECTORED TOO CLOSE TO THE PRECEDING ACFT AND GIVEN A LATE VECTOR; DSCNT APCH CLRNC. THIS ALLOWS THE FLT TO OVERSHOOT THE LOC; ABOVE THE GS. ACFT IS SENT AROUND FOR ANOTHER APCH AT DTW; MI.

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FLT TO DTW. AFTER POLAR ARR ON BASE TO RWY 3L; ASSIGNED HDG 120 DEGS AND 4000 FT; 190 KTS. THEN ASSIGNED HDG 060 DEGS; MAINTAIN 4000 FT; INTERCEPT RWY 3L LOC. FO WAS FLYING AND TURNED L ON AUTOPLT TOWARDS 060 DEGS USING 25 DEG ANGLE OF BANK. LOC BECAME ACTIVE AND WE WENT THROUGH THE LOC PASSING APPROX 070 DEGS. ATC THEN CLRED US TO TURN FURTHER L TO INTERCEPT THE LOC; MAINTAIN 4000 FT UNTIL ESTABLISHED; 180 KTS TO REVUP; CLRED ILS RWY 3L APCH. AT THIS POINT WE WERE WELL ABOVE GS AND R OF CTRLINE; CORRECTING FOR THE LATE TURN ON AND POSSIBLE TAILWIND AT 4000 FT. PF HEARD CLRED FOR THE APCH AND STARTED DSCNT TO GET ON GS; WHICH WAS NOW FULLY DEFLECTED DOWN; ACFT WAS IN EXCESS OF 2 DOTS HIGH. I; THE CAPT; READ BACK THE CLRNC AND WAS LOOKING OUT THE ACFT'S L SIDE TO CLR FOR TFC. WHEN I CAME BACK INSIDE; I NOTICED THE DSCNT AND SAID MAINTAIN 4000 FT. AT THIS POINT; THE ACFT WAS AT 3800 FT DSNDING TO JOIN THE GS. THEN THE TCASII RA WENT OFF AND A CLB WAS INITIATED. AT THE SAME TIME ATC CALLED TO ASSIGN A 300 DEG HDG AND CLB TO 5000 FT AT 170 KTS. THE BOTTOM LINER IS WE STARTED A DSCNT BEFORE ESTABLISHED ON THE APCH. I DIDN'T CATCH THE DSCNT BECAUSE I ALLOWED MYSELF TO GET DISTR LOOKING OUTSIDE THE ACFT WHEN I SHOULD HAVE BEEN INSIDE. ALSO; WHEN I DID NOTICE THE DSCNT; I SHOULD HAVE TAKEN IMMEDIATE ACTION; IE; CTL OF THE ACFT INSTEAD OF CALLING IT OUT AND WAITING FOR THE FO TO RESPOND. THERE WAS SOME HESITATION ON HIS PART BECAUSE HE BELIEVED HE WAS CLRED FOR THE APCH AND WAS 2 DOTS HIGH ON THE GS EVEN THOUGH THE LOC WAS NOT CTRED. THERE IS NO REASON FOR A TRANSPORT CATEGORY ACFT TO BE VECTORED TO FINAL THAT REQUIRES A 30 DEG ANGLE OF BANK TO INTERCEPT; NOR SHOULD WE BE ABOVE GS. DURING BUSY PERIODS THE VECTORS HAVE TO BE BETTER THAN TODAY. MAYBE LESS ACFT PER HR; OR LONGER FINALS. NO SLAM DUNKS. FATIGUE -- PREVIOUS DAY WAS 12 HRS 55 MINS LONG WITH A 9 HR OVERNIGHT CUT SHORT BY EARLY WAKE-UP BY CREW SCHEDULERS FOR RESCHEDULING. 9 HR OVERNIGHTS ARE TOO SHORT AND DANGEROUS! THIS WAS DAY #5 OF A 5 DAY TRIP. I WAS TIRED. IT IS VERY DIFFICULT TO GET AN ADEQUATE NIGHTS SLEEP WITH 9 HRS FROM RELEASE TO RPT.