CL65 CREW HAD AUTOPLT FLT CTL PROBS ON APCH AT BWI.

Narrative

THE FOLLOWING DESCRIBES THE SEQUENCE OF EVENTS THAT LED TO A BOTCHED APCH AND A RESULTING MISSED APCH. WE WERE BEING RADAR VECTORED FOR THE ILS 10 IN BWI FROM THE NW. THERE WAS A COLD FRONT MOVING THROUGH THE AREA; AND WE HAD EXPERIENCED STRONG WINDS BOTH ON THE SURFACE AND AT ALT ALL DAY. ATC GAVE US THE CLRNC; 'FLY HDG 120 DEGS; MAINTAIN 2500 FT UNTIL ESTABLISHED; 170 UNTIL 4 DME; CLRED FOR THE ILS 10 APCH.' AT 2500 FT; WINDS WERE SSE AT 60 KTS. DUE TO THE SHALLOW VECTOR INTERCEPT AND THE WINDS ALOFT AT THE TIME; WE DID NOT CAPTURE THE LOC COURSE UNTIL INSIDE COLLUM. THE AUTOPLT CAPTURED THE LOC COURSE. HOWEVER; THE GS WAS 1/2 SCALE BELOW -- WE WERE STILL AT 2500 FT. 1500 FT WAS SELECTED ON THE ALT SELECT; AND A DSCNT OF 1000 FPM DOWN WAS SELECTED TO CAPTURE THE GS. WITHIN A FEW SECONDS; THE AUTOPLT CAPTURED THE GS AND PITCHED THE ACFT DOWN OVER 12 DEGS TO CAPTURE THE GS. WE RECEIVED A 'SINK RATE' GPWS MESSAGE. I DISCONNECTED THE AUTOPLT TO ARREST THE DSCNT RATE. AT THIS POINT; WE WERE OFF GS AND STRAYING OFF LOC. I DISCONNECTED THE AUTOPLT AND EXECUTED A MISSED APCH AT 800 FT. ATC ASSIGNED RWY HDG. AT 1800 FT; ATC ASSIGNED 'MAINTAIN 2000 FT.' 2500 FT WAS SET IN THE ALT PRESELECT; AND WE WERE CLBING AT 4300 FPM. I SELECTED 'ALT' TO ARREST THE ASCENT RATE AND LEVEL AT 2000 FT. HOWEVER; DUE TO THE NATURE OF THE AUTOPLT WHICH WAS ON AT THIS POINT; THE ACFT CLBED TO 2800 FT BEFORE IT GRADUALLY LOWERED THE NOSE TO LEVEL AND THEN EVEN FURTHER TO DSND. APCH WAS YELLING AT US; SO I DISCONNECTED THE AUTOPLT AGAIN AND PITCHED DOWN TO REACQUIRE 2000 FT. WE WERE VECTORED BACK AROUND FOR ANOTHER APCH AND LANDED WITHOUT ANY FURTHER INCIDENT. CONTRIBUTING FACTORS: 1) POOR AWARENESS OF WINDS ALOFT BY BOTH US AND THE CTLR GIVING THE VECTORS; 2) RELUCTANCE ON OUR PART TO GO MISSED IMMEDIATELY AND NOT SALVAGE THE BOTCHED APCH; 3) ATC ASSIGNING A LOWER ALT TO MAINTAIN WHILE WE WERE TOO QUICKLY ENRTE TO THE PUBLISHED MISSED ALT.