EMB120 ACFT ON VECTORS FOR APCH AND TRYING TO ACQUIRE ARPT VISUALLY; FLC REALIZED THAT THE ACFT WAS HIGH ON APCH AND RPTR CAPT COMMENCED DSCNT; BUT WENT BELOW GS INTERCEPT ALT. RPTR CORRECTED BACK AS CTLR QUERIED THEIR ALT.

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IT WAS OUR FINAL ROUND TRIP OF A BUSY 3 DAY PAIRING. WE WERE 1 HR LATE DEPARTING EWR BECAUSE OF RAMP AND GND DELAYS. I BELIEVE THAT THIS FACTORED GREATLY INTO THE INCIDENT THAT TOOK PLACE (WE WERE IN A HURRY). WHILE APCHING ITH; WE RECEIVED A DSCNT CLRNC TO 3300 FT MSL. APCH CALLED THE ARPT AT 12 O'CLOCK; BUT IT WAS VERY HAZY AND NEITHER I (THE PF) OR MY FO HAD THE FIELD IN SIGHT. WE WERE LNDG ON RWY 32 SO WE KNEW (AND FULLY BRIEFED) A STRAIGHT-IN APCH. AFTER SEARCHING; WE FINALLY SAW THE ARPT AND I REALIZED THAT WE WERE EXTREMELY HIGH FOR THE APCH. DURING THIS BRIEF TIME THE CTLR ISSUED A HEADING TO INTERCEPT THE LOC. I LOOKED DOWN AT MY NAV INSTS (EADI) AND NOTICED A FULL-DOWN DEFLECTION OF THE GS NEEDLE. IT WAS DURING THIS BRIEF PERIOD THAT I DEPARTED 3300 FT MSL AND DSNDED TO APPROX 3000 FT MSL. I THOUGHT WE HAD BEEN CLRED FOR THE VISUAL APCH. I RECOGNIZED MY MISTAKE AND TOOK CORRECTIVE ACTION TO CLB BACK TO OUR ASSIGNED ALT. THE CTLR NOTICED THIS ACTION AND ASKED 'IF WE LEFT 3300 FT.' WE SAID WE DID AND ALSO CALLED THE ARPT IN SIGHT. HE ISSUED A VISUAL APCH AND APPROVED A 270 DEG TURN BECAUSE WE WERE STILL HIGH. WE LANDED WITHOUT FURTHER INCIDENCE. THIS INCIDENT HAPPENED BECAUSE WE WERE IN A HURRY TO MAKE TIME UP AND ALSO DUE TO EXPECTANCY -- I SAW HOW HIGH WE WERE AND JUST ASSUMED WE HAD BEEN CLRED FOR THE APCH. NEXT TIME I WILL ASK FOR A DELAY VECTOR AND PLAN AHEAD BETTER.